CN105278267A - Reflective vertical measurement apparatus for multi-off-axis mirror surface - Google Patents
Reflective vertical measurement apparatus for multi-off-axis mirror surface Download PDFInfo
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- CN105278267A CN105278267A CN201410329371.4A CN201410329371A CN105278267A CN 105278267 A CN105278267 A CN 105278267A CN 201410329371 A CN201410329371 A CN 201410329371A CN 105278267 A CN105278267 A CN 105278267A
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- aspheric surface
- axis aspheric
- surface catoptron
- branch road
- vertical
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Abstract
The invention discloses a reflective vertical measurement apparatus for a multi-off-axis mirror surface. The reflective vertical measurement apparatus is characterized by comprising a measurement light beam formed by a light ray from a light source by passing through an illumination optical system; the measurement light beam passes through a measurement optical system; the measurement optical system comprises a projection branch, a to-be-measured object and a detection branch; the measurement light beam passes through a projection graphic forming unit of the projection branch and an off-axis non-spherical reflector group with refractive power of the projection branch in sequence to reach the surface of the to-be-measured object; the reflective light beam, on the surface of the to-be-measured object, of the measurement light beam passes through the off-axis non-spherical reflector group with refractive power of the projection branch and a projection graphic receiving unit of the detection branch in sequence to be detected by a detector so as to obtain the vertical information of the surface of the to-be-measured object.
Description
Technical field
The present invention relates to a kind of integrated circuit equipment manufacturing field, particularly relate to a kind of reflective many from axle minute surface vertical measuring set.
Background technology
Along with projection aligner's operation wavelength constantly reduce, numerical aperture constantly increases, its measuring accuracy to silicon chip face vertical measuring set requires also day by day harsh.Affecting one of key factor of silicon chip face vertical measuring set measuring accuracy is the interference between layers effect that measuring beam produces after the figure of silicon chip face multilayer complexity.For addressing this problem, generally adopt at present visible near infrared broad spectrum light source for silicon chip face vertical measuring set provides illumination, with the interference between layers effect of homogenize different wave length illumination light, US2010/0233600 has done detailed introduction to this.Adopt and provide illumination can improve the Technological adaptability of silicon chip face vertical measuring set to a certain extent near infrared broad spectrum light source for silicon chip face vertical measuring set as seen, reduce measuring error, improve measuring accuracy.But this technical scheme following is still likely being discontented with sufficient projection aligner to the measuring accuracy demand of silicon chip face vertical measuring set.For improving the Technological adaptability of silicon chip face vertical measuring set further, reducing measuring error, improving measuring accuracy, US2010/0233600 gives with short wavelength light source as silicon chip face vertical measuring set provides the scheme of illumination.When incident angle is certain, the reflectivity of silicon chip face photoresist reduces along with operation wavelength and increases, but the reflectivity of silicon chip face underlying graphics reduces along with operation wavelength and reduces, therefore adopt short wavelength's illumination can significantly interference effect between lower layer, thus reduction measuring error, improve measuring accuracy.Described in US2010/0233600, the operation wavelength of silicon chip face vertical measuring set can at ultraviolet band, even can with projection objective operation wavelength mutually overlapping.This seems has run counter to the sacred rule that measuring beam and exposing light beam operation wavelength can not be overlapping, but in fact, if make the threshold exposure of energy lower than photoresist of measuring beam, measuring beam can not make silicon wafer exposure; Further, even if the energy of measuring beam is higher than the threshold exposure of photoresist, if but know the impact of this measuring beam on critical size, and this impact is fed back to the lighting control unit of projection objective, the lighting control unit of projection objective adjusts exposure dose in real time according to this impact, the operation wavelength of silicon chip face vertical measuring set still can with projection objective operation wavelength mutually overlapping.
But the optical system of silicon chip face vertical measuring set adopts transmission-type mostly at present, the optical system structure of the vertical measuring set of different operating wavelength is totally different, and the differences in materials of lens is also very large.If employing ultraviolet is thrown light on to the wide spectral of short-wavelength visible light, such as 50-500nm, will bring lot of challenges to the Optical System Design of silicon chip face vertical measuring set, serious aberration is exactly one of them.
Summary of the invention
In order to overcome the defect existed in prior art, the present invention is open a kind of reflective many from axle minute surface vertical measuring set, can effectively avoid ultraviolet to be difficult to the problem of rectification to aberration during the wide spectral illumination of short-wavelength visible light.
In order to realize foregoing invention object, the present invention discloses and a kind ofly adopts reflective many vertical measuring sets from axle minute surface, it is characterized in that, comprise: the light that a light source sends forms a measuring beam after a lamp optical system, described measuring beam measures optical system through one, and described measurement optical system is made up of projection branch road, object under test and a detection branch road; Described measuring beam successively through the projecting figure forming unit of described projection branch road, described projection branch road there is the off-axis aspheric surface catoptron group of refractive power after arrive described object under test surface; The folded light beam of described measuring beam on described object under test surface is detected by a detector successively after the off-axis aspheric surface catoptron group with refractive power of described detection branch road and the projecting figure receiving element of described detection branch road, to obtain the vertical information on described object under test surface.
Further, described projection branch road and detection branch road also comprise some catoptron groups, for make described measuring beam the structural constraint of light path meeting spatial and/or for signal madulation.
Further, the off-axis aspheric surface catoptron group of described projection branch road comprises successively: the first off-axis aspheric surface catoptron group, the second off-axis aspheric surface catoptron group, the 3rd off-axis aspheric surface catoptron group and the 4th off-axis aspheric surface catoptron group.
Further, the off-axis aspheric surface catoptron group of described detection branch road comprises successively: the 5th off-axis aspheric surface catoptron group, the 6th off-axis aspheric surface catoptron group, the 7th off-axis aspheric surface catoptron group and the 8th off-axis aspheric surface catoptron group.
Further, the focus of described first off-axis aspheric surface catoptron and the second off-axis aspheric surface catoptron is closer to each other or overlap, the focus of described 3rd off-axis aspheric surface catoptron and the 4th off-axis aspheric surface catoptron is closer to each other or overlap, the focus of described 5th off-axis aspheric surface catoptron and the 6th off-axis aspheric surface catoptron is closer to each other or overlap, and the focus of described 7th off-axis aspheric surface catoptron and the 8th off-axis aspheric surface catoptron is closer to each other or overlap.
Further, this projection branch road and detection branch road are the heart branch road two far away meeting SC condition.
Further, a relay optical unit is also comprised between this projecting figure receiving element and this photodetector.
Further, a field lens is also comprised between the 8th off-axis aspheric surface catoptron group and this projecting figure receiving element.
Further, this projecting figure forming unit and this projecting figure receiving element are the figure of transmission-type grating, reflective gratings or slit composition, or the combination of above-mentioned figure.
Further, described detector is photodetector, light intensity signal is converted into electric signal and is transported to a computing machine by described photodetector, and described computing machine calculates the vertical information of described object under test according to described electric signal, and described vertical information comprises vertical position and rotation information.
Compared with prior art, the present invention both can avoid ultraviolet to be difficult to the problem of correcting to aberration during the wide spectral illumination of short-wavelength visible light, also can reduce the complexity of silicon chip face vertical measuring set optical system simultaneously.
Accompanying drawing explanation
Can be further understood by following detailed Description Of The Invention and institute's accompanying drawings about the advantages and spirit of the present invention.
Fig. 1 is reflective many schematic diagrams from axle minute surface vertical measuring set involved in the present invention;
Fig. 2 is reflective many measuring system figure from axle minute surface vertical measuring set involved in the present invention.
Embodiment
Specific embodiments of the invention are described in detail below in conjunction with accompanying drawing.
The present invention devises a kind of reflective many from axle minute surface vertical measuring set, comprises lighting source, measurement optical system and photodetector and computing machine; Measure optical system to be made up of the branch road that projects, object under test (being generally silicon chip) and detection branch road; Projection route has the off-axis aspheric surface catoptron group of refractive power, projecting figure forming unit and for making the structural constraint of light path meeting spatial and/or forming for the plane mirror group of signal madulation; Detection route has the off-axis aspheric surface catoptron group of refractive power, projecting figure forming unit and for making the structural constraint of light path meeting spatial and/or forming for the plane mirror group of signal madulation.
Wherein, the purposes one of plane mirror makes the structural constraint of light path meeting spatial, due to limited space, need make vertical measuring set compact conformation, to adapt to limited space by this type of catoptron turnover light path; Purposes two is for signal madulation, vertical measuring set comprises aperture diaphragm, the periodic vibration being positioned at aperture diaphragm face and neighbouring catoptron thereof can cause the periodic wobble of image planes hot spot, the light intensity cyclical variation through projecting figure receiving element can be made, thus play the effect of signal madulation.
Especially, a projection route only comprises the off-axis aspheric surface catoptron that 4 have refractive power, is respectively the first off-axis aspheric surface catoptron, the second off-axis aspheric surface catoptron, the 3rd off-axis aspheric surface catoptron and the 4th off-axis aspheric surface catoptron and projecting figure forming unit and for making the structural constraint of light path meeting spatial and/or the plane mirror for signal madulation; Detection branch road only comprises the off-axis aspheric surface catoptron that 4 have refractive power, is respectively the 5th off-axis aspheric surface catoptron, the 6th off-axis aspheric surface catoptron, the 7th off-axis aspheric surface catoptron and the 8th off-axis aspheric surface catoptron and projecting figure receiving element and for making the structural constraint of light path meeting spatial and/or the plane mirror for signal madulation.
Alternatively, reflectively manyly can also comprise lamp optical system, relay optical system from axle minute surface vertical measuring set, lamp optical system can comprise aspheric surface reflector and some the auxiliary even optical elements that focus is positioned at light source place, and this reflector is parabola especially.
Especially, projection branch road and detection branch road are the heart branch road two far away meeting SC condition, and wherein SC condition is Scheimpflug condition, introduces see WarrenJ.Smith " ModernOpticalEngineering " FourthEdition, chapter4.5 in detail.
Especially, measure the asphericity coefficient of optical system each off-axis aspheric surface catoptron and their off-axis angles each other have passed through meticulous calculating, to make to measure the point source image confusion heart angle far away of optical system, image space deviation IPD (ImagePostionDifference), focal plane depart from FPD (FocusPositionDifference) and meet or surmount measuring accuracy demand.
Projecting figure forming unit and projecting figure probe unit can be various transmission-type gratings, various reflective gratings or the graphics set that is made up of various slit,
Ultraviolet to the short-wavelength visible light sent from light source directly can illuminate the projecting figure forming unit measuring optical system projection branch road, or after optical fiber and/or the even light of illuminator, illuminate the projecting figure forming unit measuring optical system projection branch road, thus obtain measuring beam, measuring beam is successively through the first off-axis aspheric surface catoptron, second off-axis aspheric surface catoptron, 3rd off-axis aspheric surface catoptron and the 4th off-axis aspheric surface catoptron arrive object under test, projecting figure is formed on object under test, after object under test reflection, successively through the 5th off-axis aspheric surface catoptron, 6th off-axis aspheric surface catoptron, projecting figure receiving element is arrived after 7th off-axis aspheric surface catoptron and the 8th off-axis aspheric surface catoptron, finally directly arrive photodetector or arrive photodetector after relay optical system, light intensity signal is converted into electric signal and is transported to computing machine by photodetector, computing machine calculates the vertical position Z of object according to this electric signal, the rotation Rx of rotating object, the vertical information such as Ry.
Especially, although it is total-reflection type that the present invention highlights aforementioned vertical measuring set, art technician can be according to actual needs, position suitable in the optical path adds the optical element to wide spectral has high permeability, the material (such as fused quartz) of low dispersion is made, this reality in disposal route is still consistent with the present invention, and this vertical measuring set is refraction-reflection type.
Below with reference to attached Fig. 1 and 2, the present invention is described.
Fig. 1 is reflective many schematic diagrams from axle minute surface vertical measuring set involved in the present invention, comprises lighting source 101, lamp optical system 103, measures optical system 104, relay optical system 105, photodetector 106 and computing machine 107.Wherein connected by optical fiber 102 between lighting source 101 and lamp optical system 103.
As shown in Figure 2, measure optical system 104 to be made up of projection branch road, object under test (being generally silicon chip) 210 and detection branch road.A projection route only comprises the off-axis aspheric surface catoptron that 4 have refractive power, is respectively the first off-axis aspheric surface catoptron 201, second off-axis aspheric surface catoptron 202, the 3rd off-axis aspheric surface catoptron 203 and the 4th off-axis aspheric surface catoptron 204 and projecting figure forming unit 10 and for making the structural constraint of light path meeting spatial and the plane mirror 211 for signal madulation.Detection branch road only comprises the off-axis aspheric surface catoptron that 4 have refractive power, is respectively the 5th off-axis aspheric surface catoptron 205, the 6th off-axis aspheric surface catoptron 206, the 7th off-axis aspheric surface catoptron 207 and the 8th off-axis aspheric surface catoptron 208 and projecting figure receiving element 20 and for making the plane mirror 211 of light path meeting spatial structural constraint.Preferably, the focus of the first off-axis aspheric surface catoptron, the second off-axis aspheric surface catoptron is closer to each other or overlap, the focus of the 3rd off-axis aspheric surface catoptron, the 4th off-axis aspheric surface catoptron is closer to each other or overlap, the focus of the 5th off-axis aspheric surface catoptron, the 6th off-axis aspheric surface catoptron is closer to each other or overlap, and the focus of the 7th off-axis aspheric surface catoptron, the 8th off-axis aspheric surface catoptron is closer to each other or overlap.
Projection branch road and detection branch road are the heart branch road two far away meeting SC condition.
Projecting figure forming unit 10 and projecting figure probe unit 20 can be various transmission-type gratings, various reflective gratings or the graphics set that is made up of various slit.
Ultraviolet to the short-wavelength visible light sent from light source 101 illuminates the projecting figure forming unit 10 measuring optical system projection branch road after optical fiber 102 and the even light of illuminator 103, thus obtains measuring beam.Measuring beam successively arrives object under test 210 through the first off-axis aspheric surface catoptron 201, second off-axis aspheric surface catoptron 202, the 3rd off-axis aspheric surface catoptron 203 and the 4th off-axis aspheric surface catoptron 204, is formed on object under test 210 by projecting figure in glancing incidence mode.After object under test reflection 210, successively after the 5th off-axis aspheric surface catoptron 205, the 6th off-axis aspheric surface catoptron 206, the 7th off-axis aspheric surface catoptron 207 and the 8th off-axis aspheric surface catoptron 208, arrive projecting figure receiving element 20, last directly arrive photodetector 106 or through relay optical system 105 (some photodetector does not allow excessive angle of incidence of light, therefore need relay optical system with reduce to incide photodetector angle) arrive photodetector 106 afterwards.Light intensity signal is converted into electric signal and is transported to computing machine 107 by photodetector 106, and computing machine 107 calculates the vertical information such as the vertical position Z of object, rotation Rx, Ry of rotating object according to this electric signal.
Although above-described embodiment gives total-reflection type vertical measuring set, art technician can be according to actual needs, position suitable in the optical path adds the optical element to wide spectral has high permeability, the material (such as fused quartz) of low dispersion is made, and this reality in disposal route is still consistent with the present invention.Such as, be correct the curvature of field, can after the 8th off-axis aspheric surface catoptron 208 in the above-described embodiments, add the field lens that fused silica material makes before projecting figure receiving element 20, with partly compensation point source image difference and/or field aberration.
Just preferred embodiment of the present invention described in this instructions, above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art, all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.
Claims (10)
1. one kind adopts reflective many vertical measuring sets from axle minute surface, it is characterized in that, comprise: the light that a light source sends forms a measuring beam after a lamp optical system, described measuring beam measures optical system through one, and described measurement optical system is made up of projection branch road, object under test and a detection branch road; Described measuring beam successively through the projecting figure forming unit of described projection branch road, described projection branch road there is the off-axis aspheric surface catoptron group of refractive power after arrive described object under test surface; The folded light beam of described measuring beam on described object under test surface is detected by a detector successively after the off-axis aspheric surface catoptron group with refractive power of described detection branch road and the projecting figure receiving element of described detection branch road, to obtain the vertical information on described object under test surface.
2. vertical measuring set as claimed in claim 1, is characterized in that, described projection branch road and detection branch road also comprise some catoptron groups, for make described measuring beam the structural constraint of light path meeting spatial and/or for signal madulation.
3. vertical measuring set as claimed in claim 1, it is characterized in that, the off-axis aspheric surface catoptron group of described projection branch road comprises successively: the first off-axis aspheric surface catoptron group, the second off-axis aspheric surface catoptron group, the 3rd off-axis aspheric surface catoptron group and the 4th off-axis aspheric surface catoptron group.
4. vertical measuring set as claimed in claim 3, it is characterized in that, the off-axis aspheric surface catoptron group of described detection branch road comprises successively: the 5th off-axis aspheric surface catoptron group, the 6th off-axis aspheric surface catoptron group, the 7th off-axis aspheric surface catoptron group and the 8th off-axis aspheric surface catoptron group.
5. vertical measuring set as claimed in claim 4, it is characterized in that, the focus of described first off-axis aspheric surface catoptron and the second off-axis aspheric surface catoptron is closer to each other or overlap, the focus of described 3rd off-axis aspheric surface catoptron and the 4th off-axis aspheric surface catoptron is closer to each other or overlap, the focus of described 5th off-axis aspheric surface catoptron and the 6th off-axis aspheric surface catoptron is closer to each other or overlap, and the focus of described 7th off-axis aspheric surface catoptron and the 8th off-axis aspheric surface catoptron is closer to each other or overlap.
6. vertical measuring set as claimed in claim 1, is characterized in that, described projection branch road and detection branch road are the heart branch road two far away meeting SC condition.
7. vertical measuring set as claimed in claim 1, is characterized in that, also comprise a relay optical unit between described projecting figure receiving element and described detector.
8. vertical measuring set as claimed in claim 4, is characterized in that, also comprise a field lens between described 8th off-axis aspheric surface catoptron group and described projecting figure receiving element.
9. vertical measuring set as claimed in claim 1, is characterized in that, described projecting figure forming unit and described projecting figure receiving element are the figure of transmission-type grating, reflective gratings or slit composition, or the combination of above-mentioned figure.
10. vertical measuring set as claimed in claim 1, it is characterized in that, described detector is photodetector, light intensity signal is converted into electric signal and is transported to a computing machine by described photodetector, described computing machine calculates the vertical information of described object under test according to described electric signal, and described vertical information comprises vertical position and rotation information.
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| CN201410329371.4A CN105278267B (en) | 2014-07-11 | 2014-07-11 | A kind of reflective more off-axis minute surface vertical measuring sets |
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| CN201410329371.4A CN105278267B (en) | 2014-07-11 | 2014-07-11 | A kind of reflective more off-axis minute surface vertical measuring sets |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4804258A (en) * | 1986-05-05 | 1989-02-14 | Hughes Aircraft Company | Four mirror afocal wide field of view optical system |
| US5569930A (en) * | 1993-11-08 | 1996-10-29 | Nikon Corporation | Substrate height position detecting apparatus wherein a stop plate transmits a pattern of oblique light beams which are reflected by the substrate |
| US6016220A (en) * | 1995-11-01 | 2000-01-18 | Raytheon Company | Off-axis three-mirror anastigmat having corrector mirror |
| US6381004B1 (en) * | 1999-09-29 | 2002-04-30 | Nikon Corporation | Exposure apparatus and device manufacturing method |
| CN101221280A (en) * | 2008-01-24 | 2008-07-16 | 上海微电子装备有限公司 | Full reflection projection optical system |
| CN102981254A (en) * | 2012-12-27 | 2013-03-20 | 中国科学院长春光学精密机械与物理研究所 | Coaxial aspheric surface four-reflecting mirror optical system with long focal length short structure |
-
2014
- 2014-07-11 CN CN201410329371.4A patent/CN105278267B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4804258A (en) * | 1986-05-05 | 1989-02-14 | Hughes Aircraft Company | Four mirror afocal wide field of view optical system |
| US5569930A (en) * | 1993-11-08 | 1996-10-29 | Nikon Corporation | Substrate height position detecting apparatus wherein a stop plate transmits a pattern of oblique light beams which are reflected by the substrate |
| US6016220A (en) * | 1995-11-01 | 2000-01-18 | Raytheon Company | Off-axis three-mirror anastigmat having corrector mirror |
| US6381004B1 (en) * | 1999-09-29 | 2002-04-30 | Nikon Corporation | Exposure apparatus and device manufacturing method |
| CN101221280A (en) * | 2008-01-24 | 2008-07-16 | 上海微电子装备有限公司 | Full reflection projection optical system |
| CN102981254A (en) * | 2012-12-27 | 2013-03-20 | 中国科学院长春光学精密机械与物理研究所 | Coaxial aspheric surface four-reflecting mirror optical system with long focal length short structure |
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