CN104334312A

CN104334312A - Laser scribing with extended depth affectation into a workpiece

Info

Publication number: CN104334312A
Application number: CN201380022339.5A
Authority: CN
Inventors: J·P·赛席尔; M·曼德思; M·汉诺; M·冯达都思仁
Original assignee: IPG Microsystems LLC
Current assignee: IPG Microsystems LLC
Priority date: 2012-03-16
Filing date: 2013-03-18
Publication date: 2015-02-04
Also published as: EP2825344A1; KR20140137437A; WO2013138802A1; TW201343296A; JP2015519722A; EP2825344A4

Abstract

Systems and methods for laser scribing provide extended depth affectation into a substrate or workpiece by focusing a laser beam such that the beam passes into the workpiece using a waveguide, self-focusing effect to cause internal crystal damage along a channel extending into the workpiece. Different optical effects may be used to facilitate the waveguide, self-focusing effect, such as multi-photon absorption in the material of the workpiece, transparency of the material of the workpiece, and aberrations of the focused laser. The laser beam may have a wavelength, pulse duration, and pulse energy, for example, to provide transmission through the material and multi-photon absorption in the material. An aberrated, focused laser beam may also be used to provide a longitudinal spherical aberration range sufficient to extend the effective depth of field (DOF) into the workpiece.

Description

Make that there is in a workpiece laser cutting extending degree of depth affectation

[the intersection application of related application]

Subject application is the U.S. patent application case the 12/962nd of filing an application on December 7th, 2010, a part of continuation application of No. 050, this U.S. patent application case advocates the U.S. Provisional Patent Application case the 61/267th of filing an application on December 7th, 2009, the right of No. 190, this U.S. patent application case and this U.S. Provisional Patent Application case incorporated herein by reference.

Technical field

The invention relates to Laser Processing, more specifically, is have about making the laser cutting extending degree of depth affectation in a workpiece.

Background technology

Laser is generally used for cutting or scribing one workpiece (such as a substrate or semiconductor crystal wafer).Such as in semiconductor fabrication, a laser usually for cutting the technique of semiconductor wafer, and makes each device (or crystal grain) of being made up of this semiconductor crystal wafer separated from one another.Each crystal grain on wafer is spaced by every road (street), and laser can be used along cutting this wafer every road.A laser can be used to cut off wafer completely, or incomplete cut-off wafer by disconnecting wafer and by the remainder of wafer separately at drilling point place.Such as manufacture light emitting diode (light emitting diode; LED), time, each crystal grain on wafer corresponds to LED.

Along with the size of semiconductor devices reduces day by day, the increased number of these devices can made on single wafer.The device density of each wafer increases and also can similarly reduce the cost manufacturing each device by productivity gain.For increasing this density, expect as far as possible closely to manufacture these devices.Device location on semiconductor crystal wafer is tightr, and each device Jian Ge road is just narrower.Therefore, laser beam be precisely-positioned at narrower every Dao Nei and should device is caused minimal damage or do not cause damage condition under cutting crystal wafer.

According to a kind of technology, a laser can be focused to one of substrate or wafer and reach a partial cut with ablator on the surface.Laser cutting can perform semiconductor wafer, such as, performs (be called as front cutting (front-side scribing to the front being formed with device above of wafer; FSS)), or to the back side of wafer perform and (be called as back side cutting (back-side scribing; BSS)).Although these technology effective, but it also has shortcoming.This two technique a large amount of chip usually can be caused to produce and usually need to carry out to apply and developing technique with removing or reduce chip.The back side cutting otch that usually use one is wider and wider heat affected area (heat affected zone; HAZ), this can cause heating, and then extension can be caused to damage and light loss.

The technology of stealthy cutting (stealth scribing) is usually called as according to another kind, can by a high-NA (numerical aperture; NA) lens (such as, NA>0.8) by a Laser Focusing in an inside wafer, to cause Multiphoton Absorbtion in material.High NA lens provide a very short operating distance and the very little depth of field (depth of field; DOF).This kind of technique also has some shortcomings.Specifically, stealthy cutting may limit the thickness of wafer, may be difficult to perform on the wafer of warpage, and much slow possibly when performing on thicker wafer, is some all over just reaching separation because needing.Stealthy cutting also provides a relatively large spot size (spot size) on the surface of the wafer, and this can hinder and cuts in each intercrystalline narrow front that performs in road or require that each wafer has less crystal grain.Focus desired by cause cannot obtain at inside wafer, stealthy cutting technique also has problems when processing and having the wafer of DBR or metallic reflective coating.Stealthy cutting also needs expensive lens and strict focus tolerance, and stealthy cutting equipment has higher equipment cost and annual maintenance cost usually.

Accompanying drawing explanation

After reading following detailed description by reference to the accompanying drawings, more preferably will understand these and other feature and advantage of the present invention, in the accompanying drawings:

Fig. 1 is the schematic diagram making to have in a workpiece laser cutting system extending degree of depth affectation according to the embodiment of the present invention;

Fig. 2 is a schematic diagram of the condenser lens according to the embodiment of the present invention, and this condenser lens is for focusing on a laser beam and making spherical aberration be positioned at outside a diffraction limited region;

Fig. 3 A provides a schematic diagram of the paraxial focused laser beam without spherical aberration for lens;

Fig. 3 B to be exceeded a diffraction limited region with the schematic diagram providing to have a focused laser beam of aberration for lens by overfill, this laser beam has to be enough to the depth of field be extended into the longitudinal spherical aberration scope in a workpiece and a limited transverse spherical aberration scope;

Fig. 3 C to be exceeded a diffraction limited region with the schematic diagram providing to have a focused laser beam of aberration further for lens by overfill, this laser beam has a larger longitudinal direction and transverse spherical aberration scope;

Fig. 4 A to Fig. 4 C is a focused laser beam with aberration is positioned at different focal shift position schematic diagram relative to a surface of a workpiece;

Fig. 5 A to Fig. 5 D is that a focused laser beam enters the sapphire schematic diagram of 250 micron thickness with different focus deviation and different amount of spherical aberration from the ternary lens that has 60 millimeters of (mm) focal lengths;

Fig. 6 A to Fig. 6 D is that a focused laser beam enters the sapphire schematic diagram of 250 micron thickness with different focus deviation and different amount of spherical aberration from the binary lens that has 54 millimeters of focal lengths;

Fig. 7 A to Fig. 7 D is that a focused laser beam enters the sapphire schematic diagram of 120 micron thickness with different focus deviation and different amount of spherical aberration from the ternary lens that has 25 millimeters of focal lengths;

Fig. 8 is a photo on a surface of display one sapphire substrate, and this surface has a series of ablation hole, and these ablation holes are formed by a kind of according to an embodiment of the invention method;

Fig. 9 is a photo of the side of display one sapphire substrate, and this side has a series of extension affectations extended from ablation hole, and these extend affectation is formed by a kind of according to an embodiment of the invention method;

Figure 10 A and Figure 10 B is the schematic diagram of a laser-processing system according to one embodiment of the invention with a Workpiece fixing platform, and this Workpiece fixing platform lays respectively at an aligned position and laser machining site;

Figure 11 is a schematic side view of back side cutting according to an embodiment of the invention, and wherein a laser beam and semiconductor wafer Shang Ge road carry out aligned on opposite sides;

Figure 12 A and Figure 12 B is the schematic side view of two-sided according to an embodiment of the invention cutting, and wherein a laser beam and a more shallow back side cut carry out aligned on opposite sides; And

Figure 13 is according to another embodiment of the present invention one for extend the schematic diagram that degree of depth affectation and an elongate light beam luminous point carry out the laser cutting system cut.

Detailed description of the invention

According to embodiments of the invention, system and method for laser cutting extends degree of depth affectation by providing in a substrate or workpiece with under type: focus on a laser beam, and make this light beam utilize a waveguide self-focusing effect and enter in this workpiece, to cause crystal inside to damage along a passage extended in this workpiece.Different optical effects (optical aberration of the Multiphoton Absorbtion such as, in workpiece material, the transparency of workpiece material and focused laser beam) can be utilized to promote waveguide self-focusing effect.This laser beam can have a wavelength, pulse wave duration and pulse wave energy, such as, also to provide Multiphoton Absorbtion in the material transmitted through material at least in part.Also a focused laser beam with aberration can be used to provide to be enough to effective depth of field (depth of field; DOF) the longitudinal spherical aberration scope in workpiece is extended into.

Produce the laser cutting extending degree of depth affectation and can be used for cut workpiece (such as substrate or semiconductor crystal wafer), such as, to make die separation.According to one application, laser-processing system as herein described and method can be used for processing semiconductor wafer, to be separated for the formation of light emitting diode (light emitting diode; LED) crystal grain.Produce the laser cutting extending degree of depth affectation to can be used for carrying out back side cutting and/or front cutting to the semiconductor crystal wafer of different-thickness.The laser parameter of Multiphoton Absorbtion and optical parametric can be produced in the material transmitted through material and cut different materials to extend degree of depth affectation at least in part by selecting to make.Specifically, method as herein described can be used for cutting sapphire, silicon, glass and other can make laser beam penetrable material be simultaneously fully absorbed to cause substrate or the material of lens lesion at least in part.Producing the laser cutting extending degree of depth affectation can, preferably for such as having the workpiece of opaque coating, be also because an initial ablation can cut this opaque coating.

Term used herein " processing " refers to that any use laser energy changes the action of a workpiece, and " cutting " refers to the action of processing a workpiece by scanning laser on workpiece.Processing can damage including but not limited to the material crystals of the material ablation of surface of the work and/or inside workpiece.Cutting can comprise a series of ablation or crystal affected area and without the need to the ablation of continuous print a line or lens lesion.Term used herein " extend the degree of depth affectation " refers to the lens lesion that the passage extended along at inside workpiece due to the reciprocation of photon and material in laser energy and workpiece occurs.

Producing the laser cutting extending degree of depth affectation can ablator one outside and focus the light beam in inner to cause internal rupture or lens lesion (namely subsequently, extend degree of depth affectation), and then cause or promote cutting or stripping and slicing (dicing), such as, to make wafer die be separated.Initial ablation can cause refraction index changing, and this can promote to make laser enter waveguide or the self-focusing effect of otch, converges, and then effectively focused to by high electric field energy a bit and make this some place that lens lesion occur to produce one in material crystal structure.By laser parameter optimization to provide a clean ablation (that is, there is minimum chip), and then self-focusing effect can be promoted, below will set forth in more detail.In other embodiments, produce the laser cutting extending degree of depth affectation also to perform when not ablation surface of the work.

Can by adjustment laser parameter (such as, wavelength, pulse wave duration and pulse wave energy) to make to provide the Multiphoton Absorbtion that is enough to upset material crystal structure transmitted through material and reach and extend degree of depth affectation at least in part.Specifically, laser beam can have one can transmitted through the wavelength of workpiece material (such as, infrared light wavelength, green wavelength or ultraviolet wavelength), and one can be comprised there is ultrashort pulse wave (such as, be less than for 1 nanosecond) or short pulse wave is (such as, be less than for 200 nanoseconds) a pulse wave laser beam, and then provide a peak power that can cause Multiphoton Absorbtion.Therefore, the target transparent in fact by use one and a high-energy ultrafast laser, irradiation level (irradiance) just allows the reciprocation of carrying out dark volume range with target with the balance extending the depth of field (DOF).

Optical maser wavelength can be in infrared light (IR) scope and to can be once to quintuple harmonics, more specifically, can be in such as about 1.04 microns to 1.06 microns (IR), 514 nanometer to 532 nanometers (green glow), 342 nanometer to 355 nanometers (UV) or 261 nanometer to 266 nanometer (UV) scopes.In sapphire, such as, can reach by the optical maser wavelength being in (such as, 266 nanometers, 343 nanometers or 355 nanometers) within the scope of UV the cutting undertaken by the affectation of the extension degree of depth.In silicon, can such as be longer than 1.2 microns (now silicon starts transmission), the more particularly optical maser wavelength of about 1.5 microns and the cutting of reaching by extending degree of depth affectation and carrying out by being within the scope of IR.The optical maser wavelength be in visible range can be used to carry out glass-cutting to extend degree of depth affectation.As disclosed herein, also can transmitted through the optical maser wavelength of following material for the semiconductor with band gap (band gap) and dielectric material by using by extending cutting that degree of depth affectation carries out, these materials are including but not limited to GaAs and other III-V material, SiC, Si, GaN, AIN and diamond.

By a longer wavelength (such as, compared to existing cutting technique) with one comparatively short pulse wave together use laser energy can be made especially in highly transparent material (such as sapphire), to have better coupling efficiency and absorption.The pulse wave duration can be shorter than thermal diffusion time, so cause the rapid evaporation of material (that is, with one directly solid-gas phase become (solid to vapor transition) and reach vapo(u)rability ablation).For making the melting of some material minimize, the such as pulse wave duration can be subpicosecond.When processing sapphire, such as, can use the ultrashort pulse wave duration being less than about 10 psecs (ps).In other embodiments, the comparatively long pulse wave duration (pulse wave of 150 nanoseconds nanosecond to 200 such as, can be used in silicon) being greater than for 1 nanosecond or being even greater than for 100 nanoseconds can also be used.

Ultrafast laser such as can be used to produce the ultrashort pulse wave of psec or femtosecond (femtosecond).In certain embodiments, ultrafast laser can produce has different wave length (such as, about 0.35 micron, 0.5 micron, 1 micron, 1.3 microns, 1.5 microns, 2 microns or any increment therebetween) and the original laser light beam of different ultrashort pulse wave duration (such as, being less than about 10 psecs).One example of one ultrafast laser comprise can purchased from TruMicro series 5000 picosecond lasers of TRUMPF one of them.Laser can also be in about 10 kilo hertzs (kHz) and provide to the repetitive rate in a scope of 1000 kilo hertzs and be in about 1 micro-joule (μ J) to the pulse wave energy in a scope of 1000 micro-joules.

Produce the laser cutting extending degree of depth affectation and usually use the longer optics of operating distance (such as, using lower NA lens compared to the high NA lens cut for stealth).Have compared with the optics of long reach and lower NA can comprise such as NA be less than 0.8, be more particularly less than 0.5 or be less than 0.4 condenser lens.Produce the laser cutting extending degree of depth affectation and also can introduce spherical aberration, this spherical aberration has the longitudinal spherical aberration scope being enough to be extended into by effective DOF in a workpiece.Compared to the lens with higher NA, have, compared with the lens of long reach and lower NA, there is a longer DOF usually.Use one to introduce the lens of spherical aberration and can extend effective DOF further, and make waveguide self-focusing effect increase energy on an extension area within the workpiece.

To set forth in more detail as following, can by adjustment laser parameter (such as, wavelength, pulse wave duration and pulse wave energy), machined parameters (such as, pulse wave spacing) and optical parametric (such as, work NA and depth of focus) control the degree of depth extending degree of depth affectation.

See Fig. 1, can be used for cutting one workpiece 102 (sapphire substrate of such as semiconductor wafer) for an embodiment of carrying out a laser-processing system 100 of laser cutting by the affectation of the extension degree of depth.This embodiment of laser-processing system 100 comprises laser instrument 110 and a beam delivery system 120, laser instrument 110 is for generation of an original laser light beam, and beam delivery system 120 is for focusing on this laser beam and this focused laser beam being guided to a surface 104 of workpiece 102.Beam delivery system 120 comprises a beam expander (beam expander) 122 and a condenser lens 124, beam expander 122 is for expanding an original laser light beam 112 from laser instrument 110 to form an expansion light beam 114, and condenser lens 124 is for focusing on expansion light beam 114 to provide a focused laser beam 116.Beam delivery system 120 also can comprise an autofocus system (scheming not shown), but can be so non-essential.

In the embodiment shown, laser-processing system 100 focuses on expansion laser beam 114, and make an energy density of focused laser beam 116 be enough to the surface 104 of ablation workpiece 102 in an ablated region 106, and this light beam is made to utilize waveguide self-focusing effect and penetrate ablated region 106 and enter in workpiece 102.Therefore, focused laser beam 116 is guided to the interior location 108 extended in workpiece 102 by waveguide self-focusing effect from ablated region 106, at interior location 108 place, causes lens lesion due to vibrations, electric field and/or pressure.Each pulse wave of focused laser beam 116 forms a beam spots respectively and utilizes waveguide self-focusing effect and extend in workpiece 102 on workpiece 102, to provide high-energy and cause lens lesion at interior location 108 place along passage in an extension degree of depth.Although only use the focused laser beam 116 of single pulse wave just can be enough at each position place, but also can use the technique of pulse wave more than, wherein subsequent pulses provides more deeply or stronger material breaks.

Can on workpiece 102 scanning focused laser beam 116, and form a series of ablated region 106 and the impaired interior location of crystal 108 (that is, extending affectation) by a series of laser pulse wave along a line of cut.Such as can single pass or multipass ground scanning laser beam 116, to reach the various degree of depth and spacing.Such as, workpiece 102 can move relative to focused laser beam 116, to form this serial ablated region 106 and the impaired interior location 108 of crystal.After this ablated region 106 and the impaired interior location 108 of crystal can be conducive to the separation of workpiece 102 along line of cut.Although illustrated embodiment is presented on a semiconductor crystal wafer with LED grain carry out front cutting, but laser-processing system 100 also can be used for back side cutting or two-sided cutting, below will set forth in more detail.

Determine according to material type, laser instrument 110 can penetrate short pulse wave (such as, being less than for about 200 nanoseconds) or the ultrashort pulse wave (such as, being less than for about 1 nanosecond) that wavelength can penetrate the material of workpiece 102 at least in part.According to the example by extension degree of depth affectation cutting sapphire, laser instrument 110 is a ultrafast laser, it penetrates an original laser light beam, the wavelength of this original laser light beam to be within the scope of UV (such as, about 266 nanometers, 343 nanometers or 355 nanometers) and to have and is less than a pulse wave duration of about 10 psecs and a pulse wave energy of about 60 micro-joules.This kind of laser provides one can penetrate sapphire wavelength and a sufficiently high peak power to damage the crystal at the interior location place in sapphire.Can a repetitive rate operate lasers 110, and then the cutting of an expectation is reached with a specific sweep speed.According to the sapphire example of a processing, can one about 33.3 kilo hertz repetitive rate and be in the UV laser that one about 70 mm/second (mm/s) to the one scan speed operation of 90 mm/second (mm/s) scope has a pulse wave energy of about 60 micro-joules.In another example, repetitive rate can be about 100 kilo hertzs, and one scan speed is about 100 mm/second to 300 mm/second.In other embodiments, can one reduce pulse wave energy (such as about 40 micro-joules) and a higher repetition rate (such as, about 200 kilo hertzs) use a lower-wattage laser (such as, about 8 watts (W)).

Beam expander 122 can be one 2 × beam expanding telescope (expanding telescope), and the ternary lens that condenser lens 124 can be one 60 millimeters reach an effective focusing performance (focusability) for the desired kerf width (kerf width) of the depth of focus (focal depth) of about 400 micron (μm) and about 3 micron.Beam expander 122 can be a such as beam expanding telescope, and this beam expanding telescope comprises the negative lens (such as, f=-100 millimeter) of a uncoated and the combination of a positive lens (such as, f=200 millimeter).Condenser lens 124 can have one be less than 0.8, be more particularly less than 0.5 or be less than 0.4 NA, this can provide a longer operating distance and a longer DOF.Condenser lens 124 also can introduce spherical aberration with the focused laser beam 116 providing to have an aberration, the focused laser beam 116 with aberration has a longitudinal spherical aberration scope, this longitudinal spherical aberration scope is enough to effective DOF to extend much further in workpiece 102, below will set forth in more detail.

The combination of focused laser beam and ultrashort pulse wave or short pulse wave can make the focusing performance of enhancing (having lower NA optics) cause lens lesion at interior location 108 place of workpiece 102, the amount being removed material (such as, chip) on surface of the work 104 be minimized simultaneously.Laser instrument 110 and beam delivery system 120 may be configured with laser processing parameter (such as, wavelength, pulse wave duration, pulse wave energy, peak power, repetitive rate, sweep speed and beam length and width), these laser processing parameters can be reached for for the ablated surface of cutting material and self-focusing effect and the kerf width reaching expectation.

As Fig. 2 shows in greater detail, can, by the effective DOF utilizing the lens aberration of a condenser lens 224 extension one to have the focused laser beam 216 of aberration, promote to extend degree of depth affectation.Lens aberration is the deviation that light passes relative to an ideal path after lens, and this ideal path predicts by paraxial optics device.Specifically, spherical aberration is produced through deviation farther relative to lens axis after lens by light.

In this embodiment, a part for condenser lens 224 comprises a diffraction limited region 223 usually, and diffraction limited region 223 can provide the diffraction limited usefulness of aberrationless (that is, the impact of diffraction on usefulness exceedes the impact of aberration on usefulness) in fact.Focus on paraxial focal plane 226 place at the light 213 of a laser beam 214 of diffraction limited region 223 internal radiation lens 224, and then in this region of focused laser beam 216, produce the focused beam spot that has high-res.Outside diffraction limited region 223, spherical aberration is introduced into by condenser lens 224 to be had in the focused laser beam 216 of aberration.Depart from paraxial focus at the light 215 of diffraction limited region 223 external exposure lens 224 and be focused (that is, the optical axis crossing lens 224) in the focus of expansion place at rear, paraxial focal plane 226.Therefore, spherical aberration can make the focus of the focused laser beam 216 with aberration extend continuously from paraxial focus effectively.

The distance that the focus with the light 215 of aberration extends beyond paraxial focal plane 226 along the optical axis of lens 224 is longitudinal spherical aberration (longitudinal spherical aberration; LSA) scope, and the light 215 with aberration is transverse spherical aberration (transverse spherical aberration along the distance that paraxial focal plane 226 extends; TSA) scope.LSA scope makes effective DOF 228 of focused laser beam 216 extend beyond paraxial focal plane 226 and is conducive to producing in a workpiece extending degree of depth affectation, below will set forth in more detail.

Therefore, various embodiments of the present invention utilize the flaw of a condenser lens in the mode contrary with existing knowledge.For in the lens combination of laser cutting, usually expect the beam spots avoided or correcting lens aberration provides a focusing good.But, according to embodiments of the invention, then utilize lens aberration to form an optical effect that can extend DOF wittingly, to cut a workpiece by extension degree of depth affectation.In addition, as described herein, for by extend degree of depth affectation carry out laser cutting lens can high NA lens needed for more stealthy cutting more cheap.

Condenser lens 224 can comprise multielement lens (such as binary lens or ternary lens), and this multielement lens is aberration correction in diffraction limited region 223 but not on the whole aperture of lens 224.Condenser lens 224 operating distance relatively grown also can be provided and be less than about 0.8, be more particularly less than about 0.5 or be less than about 0.4 low NA.Different baseplate materials and thickness can have the different optimal parameter combination for being undertaken cutting by the affectation of the extension degree of depth, comprise wavelength, pulse wave duration, work NA, longitudinal spherical aberration scope and defocus.Therefore, the accurate optical parametric of lens will depend on for cut material type.

As shown in Fig. 3 A to Fig. 3 C, condenser lens 224 can be designed and/or irradiate to introduce a longitudinal spherical aberration scope being enough to extend effective DOF, with limit transverse spherical aberration scope.For example, the work of lens 224 or running NA (or F#) can through selecting with the longitudinal spherical aberration scope obtaining the extension affectation by providing expectation in a workpiece 202, with limit transverse spherical aberration scope, and make the focused beam spot size on a surface 204 of workpiece 202 can not be excessive.Expectation beam spots size on surface of the work 204 depends on embody rule, and can be less than about 20 microns for cutting semiconductor wafer and die separation.

In this embodiment, can by with under type adjustment lens 224 work or running NA: use a beam expander 222 to expand an original laser light beam 212, to produce an expansion laser beam 214, expansion laser beam 214 irradiates a variable part of the clear aperature (clear aperture) of lens 224.When expansion laser beam 214 is only when the aperture of diffraction limited region 223 internal radiation lens 224, as shown in Figure 3A, focused beam 216 only comprises the paraxial rays focusing to paraxial focal plane, and this paraxial focal plane is shown on the surface 204 of workpiece 202.This can not provide and make effective DOF longitudinal spherical aberration scope extended in workpiece 202 provide the affectation of the extension degree of depth.

When irradiating the aperture of lens 224 when expanding laser beam 214 and just having exceeded diffraction limited region 223, as shown in Figure 3 B, focused beam 216 also comprises the light with aberration, and these light are can extend into a longitudinal spherical aberration zone focusing in workpiece 202 outside paraxial focal plane by DOF 228.Because when lens, in working nearby, diffraction is not very preponderated by longitudinal spherical aberration of prescribing a time limit, therefore the transverse spherical aberration scope with the light of aberration of focused beam 216 can be restricted.Therefore, longitudinal spherical aberration scope can extend DOF and simultaneously still to keep horizontal spot size to be in Guaranteed.

When expanding laser beam 214 and irradiating the whole aperture of lens 224, as shown in Figure 3 C, focused beam 216 comprises the light with aberration, and these light with aberration extend transverse spherical aberration scope further and increase the beam spots size on the surface 204 of workpiece 202 further.In this example, the extension DOF effect that the transverse spherical aberration scope of increase can make longitudinal spherical aberration provide lost efficacy.

Therefore, lens 224 can be irradiated by a work NA, and make longitudinal spherical aberration scope be enough to DOF to extend in workpiece, with produce expectation the affectation of the extension degree of depth and with limit transverse spherical aberration scope.Beam size (such as, increasing work NA) can be increased gradually, until finding till the material internal of workpiece 202 produces the best size extending degree of depth affectation in lens 224 place.Limit horizontal spherical aberration scope and can make that the beam spots size on surface of the work diminishes, laser zone diminishes and ablated region diminishes, still can reach the longitudinal spherical aberration scope that is enough to extend effective DOF simultaneously.In one embodiment, transverse spherical aberration scope can be limited fully, with produce be less than about 20 microns, more particularly 10 microns to 20 microns a laser zone and be less than about 10 microns, the more particularly ablated region of about 5 microns.

For a given material, wavelength and pulse wave duration, best NA and pulse wave energy will depend on material thickness.For thin material (such as, the sapphire of 90 microns to 110 microns), can by one about 0.15 to 0.2 work NA and be in the extension degree of depth affectation degree of depth that one about 10 micro-joule to the pulse wave energy of about 50 micro-joules of scopes reaches an expectation.When use one has the ternary lens of 25 millimeters of focal lengths and one 18 millimeters of clear aperatures, such as can reach a suitable spot size with a longitudinal spherical aberration scope by about 8 millimeters of the 18 millimeters of apertures irradiating these 25 millimeters of ternary lens, this longitudinal spherical aberration scope is enough in the material thickness of one 90 microns to 110 microns, reach the affectation of the extension degree of depth.For processing thin sapphire by psec 355 nanometer laser, such as, can operate the ternary lens that has 25 millimeters of focal lengths, to reach the extension degree of depth affectation of a desired depth by about 0.16NA.In this example, analyze according to a Zemax, longitudinal aberration coefficient is about 0.0133, and lateral aberration coefficient is about 0.0024.

For thicker material (such as, the sapphire of 250 microns to 500 microns), can by one about 0.05 to 0.1 lower work NA and the higher pulse wave energy that is in one about 30 micro-joule to 70 micro-joule of scope reach that thicker material matches with this one expect to extend degree of depth affectation.For processing thick sapphire by psec 355 nanometer laser, the ternary lens that has 60 millimeters of focal lengths can be operated, to reach the extension degree of depth affectation of a desired depth by about 0.07NA.Pulse wave energy can be higher or lower according to pulse wave spacing, to reach the degree of depth of an expectation.For example, use together with the pulse wave spacing that a lower pulse wave energy can be shorter with, and a longer pulse wave spacing can need a higher pulse wave energy.

Also can use other technologies to reduce or eliminate excessive transverse spherical aberration.For example, an aperture can be positioned over lens 224 front, to limit the largest beam diameter 214 entered in lens 224, limit maximum NA whereby.

As mentioned above, different laser parameters and optics can be utilized by the extension degree of depth affectation of the various degree of depth to cut different materials.In sapphire, the such as one ternary lens with 25 millimeters of focal lengths can reach the extension degree of depth affectation dark more than 100 microns together with a ultrafast UV laser.In silicon, by longer lens and have more high-power IR laser, a darker extension degree of depth affectation (such as, 300 microns) can be reached.

As shown in Fig. 4 A to Fig. 4 C, also can select or adjust the focus deviation of focused laser beam 216 relative to a surface 204 of a workpiece 202 that has aberration, such as, enter one in workpiece 202 extend beam spots size on the surface 204 of DOF 228 and/or workpiece 202 and energy density to change.Focus deviation can be chosen to such as make a degree of depth optimization of the extension degree of depth affectation entered in workpiece 202 and surface damage or chip are minimized.Therefore adjustable severity control can be carried out by adjusting focus deviation and other laser and optical parametric (such as laser pulse wave energy) to the affectation of the extension degree of depth.Such as can adjust focus deviation by adjustment condenser lens 224 relative to a position of workpiece 202.

Focal shift does not occur on the focused laser beam 216 that Fig. 4 A display has an aberration focuses on workpiece 202 surface 204 with paraxial rays, that is, paraxial focal plane 226 overlaps in fact with surperficial 204.Between surface 204 and paraxial focus surface 226, there is a focus deviation δ below the focused laser beam 216 that Fig. 4 B display has an aberration focuses on workpiece 202 surface 204 with adaxial ray _f, whereby effective DOF 228 is more extended in workpiece 202.Between surface 204 and paraxial focal plane 226, there is a larger focus deviation δ below the focused laser beam 216 that Fig. 4 C display has an aberration focuses on workpiece 202 surface 204 with paraxial rays _f, whereby effective DOF is further extended in workpiece 202.

Optimal focus offset amount can be different according to baseplate material (such as, the refractive index at cutting wavelength place) and material thickness, and different according to the gained aberration coefficients under lens running NA and lens operation condition.Focus deviation also can be determined according to technology type (such as, front type or back-type).Under 0.16NA, use one 25 millimeters of ternary lens to cut the situation of the sapphire substrate of one 90 microns to 110 microns for 10 psec 355 nanometer lasers, such as, optimal focus offset amount for the cutting of the back side can be in 20 microns in 40 micrometer ranges.

Fig. 5 A-Fig. 5 D is presented at the light geometry distribution of a laser beam of the ternary lens focus using one 60 millimeters of focal lengths in the sapphire of 250 micron thickness, and it has different amount of spherical aberration and the different focus deviations that are increment with 20 microns.Fig. 6 A-Fig. 6 D is presented at the light geometry distribution of a laser beam of the binary lens focus using one 54 millimeters of focal lengths in the sapphire of 250 micron thickness, and it has different amount of spherical aberration and the different focus deviations that are increment with 15 microns.Fig. 7 A-Fig. 7 D is presented at the light geometry distribution of a laser beam of the ternary lens focus using one 25 millimeters of focal lengths in the sapphire of 120 micron thickness, and it has different amount of spherical aberration and the different focus deviations that are increment with 10 microns.

The paraxial rays geometry distribution that one perfect lens will provide shown in Fig. 5 A, Fig. 6 A and Fig. 7 A.According to each embodiment described herein, an actual lens with a diffraction limited region can introduce the spherical aberration as shown in Fig. 5 B-Fig. 5 D, Fig. 6 B-Fig. 6 D and Fig. 7 B-Fig. 7 D.The light geometry distribution with the light of aberration that Fig. 5 B, Fig. 6 B and Fig. 7 B illustration are irradiated an actual lens by a uniform laser light beam in whole aperture and provided.The light geometry distribution with the light of aberration that Fig. 5 C, Fig. 6 C and Fig. 7 C illustration are irradiated an actual lens by a Gauss (Gaussian) laser beam in whole aperture and provided.The light geometry distribution with the light of aberration that Fig. 5 D, Fig. 6 D and Fig. 7 C illustration are irradiated an actual lens by a gauss laser beam at part aperture and provided.

In the example shown, as aperture excessive (Fig. 5 B, Fig. 5 C, Fig. 6 B, Fig. 6 C, Fig. 7 B and Fig. 7 C), transverse spherical aberration scope is excessive, and the focused beam with aberration can be exaggerated.Under part aperture (Fig. 5 D, Fig. 6 D and Fig. 7 D), the focused beam with aberration has the focus of a relative compact and has effective DOF of an extension compared with paraxial or perfect lens (Fig. 5 A, Fig. 6 A and Fig. 7 A).Therefore, according to an example, for particular substrate material and thickness, desired lens and NA combination can produce the horizontal spot size of almost diffraction limited, but produce simultaneously and be enough to extend effective DOF with the longitudinal spherical aberration scope matched with material thickness.

Although by having the lens of focal length of 25 millimeters, 54 millimeters and 60 millimeters to describe particular instance, but the lens with other focal lengths also can be used to provide desired NA and spherical aberration.For example, focal length can be less than 25 millimeters or be greater than 60 millimeters.

Fig. 8 and Fig. 9 display is cut a sapphire substrate 802 by a series of laser pulse wave and is made to have the photo extending degree of depth affectation in sapphire substrate 802.Each laser pulse wave forms one and supplies laser to enter ablated region or the hole 806 of sapphire substrate 802, is wherein surrounded with a laser zone 805 around ablation hole 806, and an extension degree of depth affectation passage 808 extends in the material of substrate 802 from ablation hole 806.Therefore, substrate 802 can be separated along the line of cut formed by this series of ablation hole 806 and extension degree of depth affectation passage 808.

In the embodiment shown, ablation hole 806 is about 5 microns wide and has the laser zone 805 of one 20 microns and spacing is about 15 microns, and extends degree of depth affectation passage 808 and to extend in the sapphire substrate 802 of 150 micron thickness about 100 microns.Therefore, according to embodiment as herein described, the cutting undertaken by the affectation of the extension degree of depth allows that cutting part is less than 20 microns.Therefore, in cutting, there is the semiconductor die bowlder of LED, cutting part less (compared with such as cutting with stealth), then allowed narrower (such as every road, be less than 25 microns) and intercrystalline distance is less, and significantly damage and chip can not be caused.Even if when the spacing when between cutting part is larger, the degree of depth of extension degree of depth affectation passage 808 also can improve the disconnection along line of cut.The degree of depth extending degree of depth affectation passage 808 also makes it possible to cut thicker substrate and make laser different focus place in substrate carry out multipass as such as needed for stealthy cutting.Such as, compared with the overlapping pulse wave of use, the spacing of cutting part is allowed by using single pulse wave to each cutting part and cuts quickly.

Other cutting part size, the degree of depth and spacing can be reached by different laser parameters (such as, by control pulse wave spacing and the degree of depth).Although single pulse wave can be used to each position, but also can such as scan laser and use multiple pulse wave with controlling depth by multipass to each cutting part.Although illustrated embodiment display one spacing of an about 15 microns and degree of depth of about 100 microns, but spacing can be controlled to from mutually overlapping to 20 microns or more, and severity control can be become be less than 100 microns to being greater than 200 microns.

In other modification, different depth can be used for the different pulse waves in a pulse wave sequence.One pulse wave sequence such as can comprise the higher more shallow pulse wave of a series of frequency (such as, 10 microns that open to 10 micron pitch by 5 microns to 20 micrometer depth) and a spacing frequency lower (such as, every 15 microns to 50 microns) darker pulse wave (such as, 50 microns to 100 microns).In other words, a series of darker pulse wave can be longer apart from spaced apart, and make more shallow pulse wave between darker pulse wave to strengthen turn-off characteristic.Therefore, by improvement turn-off characteristic and disconnect yield, producing the cutting extending degree of depth affectation and controllable depth and spacing can be especially favourable when producing LED, is because the light propagation effect from LED more can arrive bottom or the centre of sapphire sidewall.In the situation of wherein less concern light loss, (such as in Silicon Wafer) can use more closely and darker spacing.

With reference to Figure 10 A and Figure 10 B, according to another embodiment, a laser-processing system 1000 comprises an air supporting (air bearing) X-Y positioning table 1030, for support and location one workpiece 1002, and then cuts by the affectation of the extension degree of depth.Laser-processing system 1000 comprises the laser beam delivery system 1020 be installed on side (such as, top side or front side) and the opposite side camera 1040 be installed on an opposite side (such as, bottom side or rear side).At least one workpiece support section 1034 of positioning table 1030 be configured to the aligned position making opposite side camera 1040 towards workpiece 1002 (Figure 10 A) and make laser beam delivery system 1020 towards workpiece 1002 a Working position (Figure 10 B) between slide.Laser beam delivery system 1020 is higher than a plane 1001 of the work piece support surface on support portion 1034, and opposite side camera 1040 is lower than the plane 1001 of the work piece support surface on support portion 1034.U.S. Patent application the 12/962nd, describe in further detail an example of air supporting X-Y positioning table in No. 050, this U.S. Patent application is incorporated herein in full with way of reference.

On aligned position, opposite side camera 1040 pairs of workpiece 1002 carry out imaging and produce representing the image data of this feature towards the feature on the side 1005 of camera 1040.The image data produced by opposite side camera 1040 can be used for positioning workpieces 1002, and make such as to use those who familiarize themselves with the technology existing NI Vision Builder for Automated Inspection and alignment techniques and laser beam delivery system 1020 is alignd relative to the feature of imaging on the opposite side 1005 of workpiece 1002.On Working position, laser beam delivery system 1020 guides a focused laser beam 1016 (such as, have an extension DOF and have the focused laser beam of aberration) and uses and carrys out processing work 1002 by extending the cutting that degree of depth affectation carries out as mentioned above towards the side 1003 towards beam delivery system 1020 of workpiece 1002.

Laser-processing system 1000 also comprises a kinetic control system 1050, for the motion controlling positioning table 1030 between the alignment and/or processing period of workpiece 1002.Kinetic control system 1050 can produce alignment data according to the image data produced by opposite side camera 1040, and controls the motion of positioning table 1030 because aliging data.

Laser beam delivery system 1020 can comprise lens and other optical elements, for such as revising and focus on the original laser light beam produced by a laser instrument as mentioned above.Laser instrument (scheming not shown) such as can be located on a platform of laser-processing system 1000, and the original laser light beam produced by laser instrument can be directed in laser beam delivery system 1020.

Laser-processing system 1000 also can comprise a front camera 1044, carries out imaging on front to workpiece 1002.Front camera 1044 can be mounted to beam delivery system 1020 or other suitable location.Front camera 1044 can be coupled to kinetic control system 1050 similarly, and makes kinetic control system 1050 that the image data produced from front camera 1044 can be used to provide alignment.Therefore, laser-processing system 1000 tolerable is from the back side relative with laser beam or align from front or the side identical with laser beam.Opposite side camera 1040 and front camera 1044 can be those who familiarize themselves with the technology the existing high-res camera for the semiconductor crystal wafer that aligns in laser processing application.

Therefore, laser-processing system 1000 can be used for beam delivery system 1020 and focused laser beam 1016 intercrystallinely to align every road with each on semiconductor wafer.When proper alignment, the removable workpiece 1002 of X-Y positioning table 1030 to scan laser beam on workpiece 1002, and make a series of pulse wave such as along on a wafer each intercrystalline one every road or along wafer with every the relative side cut workpiece 1002 in road.X-Y positioning table 1030 can cut every road to be indexed into another by travelling workpiece subsequently.Optionally can repeat alignment procedure, to cut every road every Dao Nei or along other at other.

With reference to Figure 11, aligned on opposite sides can be used to be beneficial to the back side cutting of semiconductor wafer 1101, and then separate a plurality of semiconductor grain (such as, LED).Semiconductor crystal wafer 1101 can comprise a substrate 1102 (such as, sapphire) and be formed at by the one layer or more semi-conducting material (such as, GaN) in the section 1109 separated every road 1107.The side with section 1109 of semiconductor crystal wafer 1101 is called as front 1103, and opposite side is called as the back side 1105.Substrate 1102 also can have one or more layer 1104 (such as, metal) on the back side 1105 relative with section 1109.

One laser-processing system (such as, above-mentioned laser-processing system) can be used for along crystal grain section 1109 Jian Ge road 1107 cutting semiconductor wafer 1101, so that semiconductor crystal wafer 1101 is divided into each crystal grain.Therefore, semiconductor crystal wafer 1101 is aligned to and makes a laser beam 1116 between semiconductor crystal wafer 1101 Shang Sheyuge road 1107, and then aims at crystal grain section 1109 and laser beam 1116.As mentioned above, cutting semiconductor wafer 1101 can be carried out by being formed a series of ablated region 1106 with extension degree of depth affectation 1108.Forming the cutting extending degree of depth affectation and ablation especially favourable when layer 1104 is opaque, is can remove layer 1104 because of ablation and make laser beam 1116 can enter substrate 1102.In another modification, a first pass of a laser can be used to carry out ablation and remove layer 1104, and one second of a laser time scanning can provide the affectation of the extension degree of depth.

When carrying out Laser Processing to the back side 1105 of semiconductor crystal wafer 1101, semiconductor crystal wafer 1101 can be oriented to make crystal grain section 1109 on the front 1103 of wafer 1101 towards opposite side camera 1140.Therefore, opposite side camera 1140 can be used for observing the aligned in position of road, each section 1109 Jian Ge road 1107, Bing Shige 1107 relative to laser beam 1116.The back layer 1104 that is aligned in of opposite side camera 1140 is utilized to be opaque (such as, metal) and to hinder especially favourable when process side is alignd.For providing this kind of alignment, wafer 1101 is oriented to make the line of cut formed on the back side 1105 of wafer 1101 by laser beam 1116 be positioned at the width every road 1107 in front 1103 along Y-axis relative to laser beam delivery system (scheming not shown).

See Figure 12 A and Figure 12 B, aligned on opposite sides can be used to be beneficial to two-sided cutting.Generally speaking, two-sided cutting relates to form relatively shallow line of cut on two face of a workpiece, and wherein line of cut relative to wherein another line of cut substantial alignment.Form the damage that shallow line of cut can minimize or avoid may be caused by darker line of cut, having line of cut on both faces can improve disconnection yield simultaneously, is because crackle more may be propagated between line of cut.

According to a kind of exemplary methods, first semiconductor wafer 1201 can be oriented to (such as, being positioned in workpiece support) make a back side 1205 towards a laser beam delivery system (scheming not shown) and a front 1203 towards an opposite side camera 1240 (Fig. 4 A).When wafer 1201 is positioned at this position, one of them carries out imaging to each section 1209 Jian Ge road 1207 can to use opposite side camera 1240, and makes wafer 1201 can be oriented to the laser beam 1216 on the back side 1205 is alignd with Shang Ge road, front 1,203 1207.When semiconductor crystal wafer 1201 aligns, laser beam 1216 can be used to cut the back side 1205, and then form a relatively shallow back side line of cut 1206a (such as, being 20 microns or following).

Semiconductor crystal wafer 1201 can be overturn subsequently, and make front 1203 towards laser beam delivery system and the back side 1205 towards opposite side camera 1240 (Fig. 4 B).When wafer 1201 is in this position, opposite side camera 1240 couples of back side line of cut 1206a can be used to carry out imaging, and make wafer 1201 can be oriented to laser beam 1216 is alignd with back side line of cut 1206a.When semiconductor crystal wafer 1201 aligns, laser beam 1216 can be used in each section 1209 Jian Ge road 1207 to cut front 1203, to form the front line of cut 1206b with back side line of cut 1206a substantial alignment.Such as, as mentioned above, line of cut 1206b in front can comprise a series of ablated region having and extend degree of depth affectation 1208.As being provided the additional of alignment by opposite side camera 1240 or substituting, a process side camera 1244 Ke Duige road 1207 carries out imaging and aligns with every road 1207 to make laser beam 1216.

Subsequently, wafer 1201 can by being divided into each crystal grain with under type: the position along line of cut 1206a, 1206b disconnects, and crackle is propagated under the promotion extending degree of depth affectation 1208 between line of cut 1206a and 1206b.When each section 1209 corresponds to each LED, such as, front line of cut 1206b more preferably can define the edge of LED, and makes LED evenly and improve disconnection yield (such as, compared to the situation only on side with shallow line of cut).In addition, causing the possibility of adverse effect less to LED light and electric characteristics, is because the degree of depth of line of cut 1206a, 1206b is not enough to cause significant fire damage.

According to another alternative, there is the front line of cut 1206b extending degree of depth affectation 1208 and first can be formed at (such as, use process side camera 1244 provides relative to the alignment every road 1207) on front 1203.Wafer 1201 can be overturn subsequently and back side line of cut 1206a (such as, using opposite side camera 1240 to provide relative to front line of cut 1206b and/or the alignment every road 1207) can be formed overleaf on 1205.Wherein a line of cut can be shallower than another line of cut.For example, first can form more shallow line of cut (such as, being 20 microns or following), and the deeper secant of Article 2 is alignd with this more shallow line of cut.According to another modification of a two-sided cutting method, back side line of cut 1206a can be formed and extend degree of depth affectation 1208.

With reference to Figure 13, another embodiment being used for cutting a laser-processing system 1300 of a workpiece 1302 (such as, a sapphire substrate of semiconductor wafer) by the affectation of the extension degree of depth below will be described in more detail.Laser-processing system 1300 can comprise ultrafast laser 1310 and a beam delivery system 1320, ultrafast laser 1310 wavelength of penetrable material at least partly can penetrate ultrashort pulse wave (such as with one, be less than for 1 nanosecond), beam delivery system 1320 can provide the rectilinear light beam 1316 of well focussed.An embodiment of beam delivery system 1320 comprises: a beam expander 1322, for expanding the original laser light beam 1321 from ultrafast laser 1310, to form an expansion light beam 1323; One light-beam shaper 1326, for making expansion light beam 1323 be shaped, to form an oval-shaped beam 1325; And a condenser lens 1324, for focusing ellipsoidal shaped light beam 1325, to provide the rectilinear light beam 1316 of well focussed, rectilinear light beam 1316 forms a rectilinear light beam luminous point and in workpiece 1302, has an extension DOF on workpiece 1302.Beam delivery system 1320 also can comprise one or more reflector 1328, optionally to reflect and redirected laser beam.

As discussed previously, extend degree of depth affectation cutting to relate on the surface 1304 of workpiece 1302 in ablated region 1306 ablator and use a waveguide self-focusing effect laser beam 1316 to be incident upon the interior location 1308 extended workpiece 1302 in from ablated region 1306, at interior location 1308 place owing to shaking, electric field and/or pressure and cause lens lesion.Condenser lens 1324 can introduce spherical aberration as mentioned above, and wherein a longitudinal spherical aberration scope is enough to effective DOF to extend in workpiece 1302.

Beam delivery system 1320 such as can comprise can form one can the beam shaping optics of spindle astigmatism focused beam spot (variable elongated astigmatic focal beam spot), as United States Patent (USP) the 7th, 388, being described in more detail in No. 172, this United States Patent (USP) is incorporated herein in full with way of reference.This elongated astigmatism focused beam spot is greater than the width along focal axis along a length of astigmatism axle.This kind of beam delivery system can control the energy density of variable astigmatism focused beam spot with the change of spot length.Light-beam shaper 1326 such as can comprise an anamorphote (anamorphic lens) system, this anamorphic system comprises a cylindrical plano-concave lens (plano-concave lens) 1326a and cylindrical planoconvex spotlight (plano-convex lens) 1326b, and changes and can change beam spots length on workpiece and energy density once distance between these lens.

Laser-processing system 1300 can revise light beam further according to embody rule, to improve the quality of line of cut.For applying (such as at some, the back side cut) in avoid epitaxial layer leafing (delamination) problem, such as, laser-processing system 1300 can provide space filtering in the edge of light beam, to clear up the point spread function (point spread function) on the narrow direction of (clean up) light beam.

Therefore, light-beam shaper 1326 can be used for the energy density of the beam spots changed on workpiece 1302, with optimization for the fluence (fluence) of certain material or cutting operation and coupling efficiency.When performing two-sided cutting to the sapphire substrate applied once GaN, such as, the energy density of beam spots can be adjusted higher with optimization to naked sapphire cutting (namely, the back side is cut), and the energy density of beam spots can be adjusted lower with optimization to the sapphire cutting applied through GaN (that is, front cutting).In other words, the optimized laser beam luminous point in side for workpiece can be used to cut this side, can by workpiece turning, and can use and cut this opposite side for the optimized laser beam luminous point of opposite side.Therefore, light-beam shaper 1326 is without the need to adjusting laser power to change energy density and optimization fluence.

In other embodiments, a nonlinear optical crystal (such as bbo crystal or β-BaB can be used ₂o ₄) as a light-beam shaper.Bbo crystal is known is used as a frequency-doubling crystal (frequency-doubling crystal) together with a laser.Because bbo crystal provides larger walking from (walk-off) effect compared to other crystal (such as CLBO), therefore the circular light beam of the essence entering crystal can become an oval-shaped beam when leaving crystal.Although undesirably may produce walk-off effect in numerous applications, but this kind of characteristic of bbo crystal is expected wherein to have in the application of an oval-shaped beam and is provided unique advantage.

Therefore, for by extending laser-processing system that degree of depth affectation and carrying out cuts and method provides the some advantages being better than existing ablation and stealthy cutting technique.Specifically, the cutting undertaken by the affectation of the extension degree of depth can cut a workpiece (such as, a sapphire substrate of semiconductor wafer) with the heat of minimum or remarkable minimizing and chip.By minimizing or minimize produced heat and chip, low electrical damage and light loss LED can be manufactured and without the need to extra coating and cleaning procedure.By the workpiece extending cutting that degree of depth affectation carries out and be also conducive to cutting thicker workpiece and there is opaque coating or film.By extending cutting that degree of depth affectation carries out also without the need to using the complexity in existing stealthy diced system and the high NA lens of costliness and focusing system.As described herein, the cutting undertaken by the affectation of the extension degree of depth can be reached in various types of material by adjustment process parameter (such as, wavelength, pulse wave duration, pulse wave energy) and optics.

According to an embodiment, a kind of method for laser cutting one workpiece comprises: produce a laser beam with a plurality of ultrashort pulse wave, these ultrashort pulse waves have the pulse wave duration being less than for 1 nanosecond; And focus on this laser beam, and make an energy density be enough to the surface in this substrate of ablated region place ablation and be enough to the refractive index that changes in this workpiece, wherein this light beam utilizes a waveguide self-focusing effect to penetrate this ablated region and the interior location arrived in this workpiece, to cause lens lesion in this interior location place material to this workpiece.

According to another embodiment, a kind of method for laser cutting one workpiece comprises: produce a laser beam, this laser beam have be enough in the material of this workpiece, provide nonlinear multiphoton absorption a wavelength, a pulse wave duration and a pulse wave energy; Use this laser beam of a lens focus, the spherical aberration with a longitudinal spherical aberration scope introduced by these lens, this longitudinal spherical aberration scope is enough in this workpiece, provide an extension depth of field (DOF), and makes the single pulse wave of this laser beam in this workpiece, produce an extension degree of depth affectation; And scan this workpiece by this laser beam, and make a series of pulse wave produce the affectation of a series of extension degree of depth along this workpiece in a series of position.

According to an embodiment again, a kind of laser-processing system comprises: a laser instrument, for generation of a laser beam, this laser beam have be enough in the material of this workpiece, provide nonlinear multiphoton absorption a wavelength, a pulse wave duration and a pulse wave energy; And a beam delivery system, for focusing on this laser beam and guiding this laser beam towards a workpiece.This beam delivery system comprises a beam expander and lens, this beam expander is for expanding this laser beam, these lens have the spherical aberration of a longitudinal spherical aberration scope for introducing, this longitudinal spherical aberration scope is enough in this workpiece, provide an extension depth of field (DOF), and makes the single pulse wave of this laser beam in this workpiece, produce an extension affectation.This laser-processing system more comprises a Workpiece fixing platform, for this workpiece mobile to scan this laser beam on this workpiece, and makes a series of pulse wave in this workpiece, form a series of extension affectation.

Although there have been described principle of the present invention, but those who familiarize themselves with the technology should be understood that this explanation only provides but not by way of example as the restriction to the scope of the invention.Except example embodiments herein, other embodiments are also covered by the scope of the invention.Usually knowing the retouching that the knowledgeable does and replacing in technique is all regarded as being within the scope of the present invention, and scope of the present invention only limits by appended claims.

Claims

1., for a method for laser cutting one workpiece, the method comprises:

Produce a laser beam with several ultrashort pulse wave, these ultrashort pulse waves have the pulse wave duration being less than 1 nanosecond (ns); And

Focus on this laser beam, and make an energy density be enough to the surface in this substrate of ablated region place ablation and be enough to the refractive index that changes in this workpiece, wherein this light beam utilizes a waveguide self-focusing effect (waveguide self-focusing effect) to penetrate this ablated region and the interior location arrived in this workpiece, to cause lens lesion (crystal damage) in this interior location place material to this workpiece.

2. the method for claim 1, wherein focusing on this laser beam is that use one lens perform, and these lens have a numerical aperture being less than 0.8.

3. method as claimed in claim 2, wherein these lens are ternary lens (lens triplet).

4. method as claimed in claim 2, wherein these lens have the focal length of at least 25 millimeter (mm).

5. method as claimed in claim 2, wherein these lens provide an effective focusing performance (focusability) with the kerf width (kerf width) of the depth of focus (focal depth) of about 400 micron (μm) and about 3 micron.

6. the method for claim 1, wherein this laser beam has a wavelength, to provide nonlinear multiphoton absorption (nonlinear multiphoton absorption) in this material of this workpiece.

7. method as claimed in claim 6, wherein this material is sapphire, and this wavelength is in ultraviolet light (UV) scope.

8. method as claimed in claim 7, wherein produce this laser beam to comprise and produce at least one pulse wave, the pulse wave energy and that this at least one pulse wave has one about 60 micro-joule (μ J) is less than the pulse wave duration of about 10 psecs (ps).

9. method as claimed in claim 8, wherein produce this laser beam to comprise and produce several pulse wave with the repetitive rate of about 33.3 kilo hertz (kHz), and more comprise to be in one about 70 mm/second (mm/s) to the one scan speed of 90 mm/second scopes scan this laser beam on this workpiece.

10. method as claimed in claim 6, wherein this wavelength is in infrared light (IR) scope.

11. methods as claimed in claim 6, wherein this material is sapphire, this wavelength is about 355 nanometers (nm), and focusing on the ternary lens execution that this laser beam is use one 25 millimeters, these ternary lens of 25 millimeters have a work numerical aperture of one about 0.15 to 0.2 scope that is in.

12. methods as claimed in claim 6, wherein this material is sapphire, this wavelength is about 355 nanometers, and focuses on the ternary lens execution that this laser beam is use one 60 millimeters, and these ternary lens of 60 millimeters have a work numerical aperture of one about 0.05 to 0.1 scope that is in.

13. the method for claim 1, more comprise and on this workpiece, scan this laser beam with one scan speed, and make a series of pulse waves of this laser beam form a series of ablated region and the impaired interior location of crystal along a line of cut.

14. the method for claim 1, wherein focusing on this laser beam is that use one lens perform, and these lens have a numerical aperture being less than about 0.5.

15. the method for claim 1, wherein focus on this laser beam and can provide an extension depth of field (depth of field), to cause lens lesion in entering the degree of depth at least about 100 microns in this workpiece.

16. the method for claim 1, wherein this laser beam be enter one in this workpiece extend the depth of field and focus on this workpiece this on the surface.

17. the method for claim 1, wherein this laser beam enters one in this workpiece further extend the depth of field and focus on a focal shift (focus offset) place of this lower face of this workpiece.

18. the method for claim 1, wherein focus on this laser beam and can introduce spherical aberration (spherical aberration), these spherical aberrations have a longitudinal spherical aberration scope, and this longitudinal spherical aberration scope is enough to this depth of field to extend in this workpiece.

19. methods as claimed in claim 18, wherein this laser beam is a focal shift place of this lower face focusing on this workpiece.

20. methods as claimed in claim 18, wherein focus on this laser beam and comprise: overfill has an aperture of lens in a diffraction limited region, and these spherical aberrations are introduced into outside this diffraction limited region.

21. methods as claimed in claim 20, wherein these lens are by sufficiently overfill, to provide this longitudinal spherical aberration scope this depth of field extended in this workpiece, with limit one transverse spherical aberration scope.

22. methods as claimed in claim 18, wherein the spot size of this laser beam on this surface of this workpiece has a width being less than about 20 microns.

23. the method for claim 1, wherein this laser beam provides a laser zone in this surface of this workpiece to be in one about 10 micron of size to 20 micrometer ranges, and this ablated region of this surface of this workpiece is less than about 10 microns.

24. the method for claim 1, more comprise:

This laser beam is shaped, to form a variable elongated focused beam spot on the surface in this of this substrate.

25. 1 kinds of methods for laser cutting one workpiece, the method comprises:

Produce a laser beam, this laser beam have be enough in the material of this workpiece, provide nonlinear multiphoton absorption a wavelength, a pulse wave duration and a pulse wave energy;

Use this laser beam of a lens focus, the spherical aberration with a longitudinal spherical aberration scope introduced by these lens, and this longitudinal spherical aberration scope is enough in this workpiece, provide an extension depth of field (depth of field; DOF), make the single pulse wave of this laser beam in this workpiece, produce one and extend degree of depth affectation (extended depth affectation); And

Scan this workpiece by this laser beam, and make a series of pulse wave produce the affectation of a series of extension degree of depth along this workpiece in a series of position.

26. methods as claimed in claim 25, wherein this laser beam comprises several ultrashort pulse wave, and these ultrashort pulse waves have the pulse wave duration that one was less than for 1 nanosecond.

27. methods as claimed in claim 25, wherein these lens comprise a diffraction limited region, and focus on the aperture that this laser beam comprises these lens of overfill, and these spherical aberrations are introduced into outside this diffraction limited region.

28. methods as claimed in claim 27, wherein these lens are by sufficiently overfill, to provide this longitudinal spherical aberration scope this depth of field extended in this workpiece, with limit one transverse spherical aberration scope.

29. methods as claimed in claim 27, wherein the spot size of this laser beam on this surface of this workpiece has a width being less than about 20 microns.

30. methods as claimed in claim 29, wherein this extension affectation to extend in this workpiece at least 100 microns.

31. methods as claimed in claim 25, wherein these lens have a numerical aperture being less than about 0.5.

32. methods as claimed in claim 25, wherein this laser beam be focused with a paraxial focus (paraxial focal point) in this workpiece this on the surface.

33. methods as claimed in claim 25, wherein this laser beam is the focal shift place being focused this lower face in this workpiece with a paraxial focus.

34. methods as claimed in claim 25, wherein this laser beam be focused into make an energy density be enough in this workpiece of ablated region place ablation one surface.

35. methods as claimed in claim 34, wherein this laser beam provides a laser zone to be in one about 10 micron of size to 20 micrometer ranges in this surface of this workpiece, and this ablated region of this surface of this workpiece is less than about 10 microns.

36. methods as claimed in claim 25, wherein this material is sapphire, and this wavelength is in ultraviolet light (UV) scope.

37. methods as claimed in claim 25, wherein this material is silicon, and this wavelength is in infrared light (IR) scope.

38. methods as claimed in claim 25, wherein this material is glass, and this wavelength is in visible range.

39. methods as claimed in claim 25, wherein scan this workpiece by this laser beam, and make a series of single pulse wave produce the affectation of this series extension degree of depth in respective position.

40. 1 kinds of laser-processing systems, comprise:

One laser instrument, for generation of a laser beam, this laser beam have be enough in the material of this workpiece, provide nonlinear multiphoton absorption a wavelength, a pulse wave duration and a pulse wave energy;

One beam delivery system, for focusing on this laser beam and guiding this laser beam towards a workpiece, this beam delivery system comprises a beam expander (beam expander) and lens, this beam expander is for expanding this laser beam, these lens have the spherical aberration of a longitudinal spherical aberration scope for introducing, this longitudinal spherical aberration scope is enough in this workpiece, provide an extension depth of field (DOF), and makes the single pulse wave of this laser beam in this workpiece, produce an extension affectation; And

One Workpiece fixing platform, for this workpiece mobile to scan this laser beam on this workpiece, and makes a series of pulse wave in this workpiece, form a series of extension affectation.

41. laser-processing systems as claimed in claim 40, wherein this laser instrument is in order to produce a laser beam with several ultrashort pulse wave, and these ultrashort pulse waves have the pulse wave duration that one was less than for 1 nanosecond.

42. laser-processing systems as claimed in claim 40, wherein these lens have a numerical aperture being less than about 0.5.

43. laser-processing systems as claimed in claim 40, wherein these lens comprise ternary lens, and these ternary lens have a numerical aperture being less than about 0.5 at least about the focal length and of 25 millimeters.