DE102008033342A1 - Projection optics for microlithography process used in projection exposure apparatus, sets ratio between overall length and object image shift smaller than preset amount - Google Patents

Abstract

The projection optics (7) has an intermediate plane between an object plane (5) and image plane (9). The six mirrors (M1-M6) are provided in the optics such that at least one mirror has a freeform reflecting surface. The ratio between overall length (T) and object image shift (dOIS) of projection objective is set smaller between 2-12. Independent claims are included for the following: (1) optical system; (2) method of producing micro-structured component; and (3) micro-structured component.

Description

The The invention relates to a projection objective for microlithography. Furthermore, the invention relates to a projection exposure apparatus with such a projection lens, a method of manufacture a microstructured component with such a projection exposure system and a microstructured device fabricated by this method.

Projection objectives for microlithography are known inter alia from the US Pat. No. 6,266,389 B1 , of the US 2005/0134980 A1 , of the US 2007/0195317 A1 , of the US 2007/0058269 A1 , of the US 2007/0223112 A , of the US Pat. No. 6,396,067 B1 , of the US Pat. No. 6,361,176 B1 and the US Pat. No. 6,666,560 B2 ,

Regarding their total transmission, in terms of an undesirable Apodization and in terms of their space requirements have the known projection lenses, especially if they be illuminated with EUV lighting, still room for improvement.

It is therefore an object of the present invention, a projection lens of the type mentioned in such a way that its total transmission is improved and that negative apodization influences avoided or reduced. Alternatively or in addition the projection lens should be as compact as possible be.

These The object is achieved by a projection lens having the features specified in claim 1, by a projection lens with the specified in claim 2 Characteristics, by a projection lens with the specified in claim 5 Characteristics and by a projection lens with the in the claim 10 specified characteristics.

According to one The first aspect of the invention is the projection lens with at least six mirrors are executed, with at least one of the mirrors is designed as a free-form surface and where the ratio the length of the projection lens and the object-image offset of the projection lens is less than 12. Such a projection lens between the object plane and the image plane still an intermediate image plane exhibit. This makes it possible given imaging requirements to meet and at the same time the expansions of each Mirror, so its absolute reflection surface, low to hold. In an embodiment with an intermediate image plane In addition, relatively small radii of curvature of the mirrors used can be achieved realize. It is also possible to specify lens designs in which a relatively large working distance between the acted upon Reflecting surfaces and passing by the mirrors Imaging beams can be maintained. The object-image offset can absolutely have a value that's bigger than 120 mm, which is preferably greater than 150 mm and even more preferably greater than 200 mm.

at Another aspect of the invention has the projection lens at least six mirrors, of which at least one mirror is a Free-form reflecting surface has. The picture plane of this Projection lens represents the first field plane of the projection lens according to the object plane Intermediate image plane between the object plane and the image plane of the image plane Projection lens is omitted, an incident angle spectrum, that is a difference between a largest and a smallest angle of incidence for imaging rays on each one of the mirrors, kept small. This reduces the requirements for a reflective coating on the Reflect. The reflective coating can then be applied either to a highest possible peak reflection or one as possible good uniformity of reflection over the mirror surface can be optimized, being in practice no consideration for excessively varying angles of incidence must be taken on one of the mirrors. Overall results a projection lens with good overall transmission, the unwanted influence of an apodization avoided or can be reduced. The execution of at least one Mirror as free-form reflecting surface allows that even without an intermediate image plane the inventive Projection lens has low aberrations. The least Six mirrors of the projection lens allow one good picture error correction. In the inventive Projection lens may be a mirror projection lens act, that is, a projection lens in which all components, the imaging rays lead, as reflective components are executed.

One Projection lens according to claim 3 is with good separation between the object field and the image field compact. The relationship from the length and the object-image offset is preferred less than 2, more preferably less than 1.5 and even more preferred less than 1.1.

A free-form reflecting surface according to claim 4 enables a good Bildfehlerminimierung for the Projection lens. Other types of free-form surfaces are possible. Such free-form surfaces can not be described by a function which is rotationally symmetrical about an excellent axis, which is a normal to a surface portion of the mirror surface. In particular, such free-form surfaces can not be described by a conic-asphere equation and require at least two independent parameters to describe the mirror surface. With regard to the characterization of a mirror surface as a free-form surface, the form of a boundary of the optically effective mirror surface does not matter. Of course, optically effective surfaces are known from the prior art, which are not bounded rotationally symmetrical. Such optically effective surfaces are nevertheless described by a rotationally symmetric function, wherein a non-rotationally symmetrical bordered section of this optical surface is used.

The Projection lens according to claim 5 is in good spatial Separation between the object field and the image field compact. The relationship between the length and the object-image offset is preferably smaller as 1.5 and more preferably less than 1.1. Also the projection lens according to claim 4 can be implemented as a mirror projection lens be.

The Advantages of claims 6 to 9 correspond to those above with reference to the projection lenses according to the invention already executed.

at Another aspect of the invention has the projection lens a plurality of mirrors, of which at least one mirror a Free-form reflecting surface, and at least one Intermediate image plane between the object plane and the image plane, where the ratio of a length of the projection lens and an object-image offset is less than 12. By use it is also the at least one free-form reflecting surface possible with a projection lens with an intermediate image plane, to cause a significant object-image offset. This can be used in particular to the illumination light on other components of a projection exposure system, within the projection optics is inserted to pass, without this at the angles of incidence on the mirrors of the projection optics To compromise. In particular, you can for virtually all reflections of the illumination light small Angle of incidence or very large angles of incidence (grazing incidence). The intermediate image plane of the projection lens according to this aspect of the invention a bundle guide of the imaging light between the object plane and the image plane with typical bundle dimensions or bundle diameters, except for the bundle guide in the range of one last and the numerical aperture of the projection lens defining mirror are relatively small. This facilitates a vignetting control in a projection exposure with the projection optics. In addition, has a projection optics with at least an intermediate image plane at least two pupil planes, of which one between the object plane and the at least one intermediate image plane and the other between the at least one intermediate image plane and the image plane is arranged. This enlarges the possibilities of controlling lighting parameters Boundary influence in or adjacent to the pupil planes.

The Advantages of claims 11 and 12 correspond to those which above with reference to the invention Projection lenses according to the other aspects already executed.

One Beam path course of the central object field point associated Main beam according to claim 13 allows a large Object-image offset with small to moderate angles of incidence the mirrors of the projection optics. In such a main beam path there is no area of the beam path of the main beam, in which the main beam is fed back towards the normal will, resulting in achieving a large object-image offset would be counterproductive.

absolute values of the object-image offset according to claim 14 have been for a spatial separation of an illumination light beam path in front of the object field of the projection optics from the imaging beam path within the projection optics proved to be advantageous.

A ratio of an incident angle spectrum and a image-side numerical aperture according to claim 15 leads to advantageously low requirements for reflective coatings for the mirror. The angle of incidence spectrum is preferably at most 15 °, more preferably at most 13 °, more preferably at most 12 ° and even more preferably at most 10 °. Accordingly, the ratio between the incident angle spectrum and the image-side numerical aperture of the projection objective is preferably at most 60 °, more preferably at most 52 °, even more preferably at most 48 °, and still more preferably at most 40 °. Here, a picture-side numerical aperture of 0.25 may be present. Also, another image-side numerical aperture in the range between 0.25 and 0.9, for example, that is, a picture-side numerical aperture of, for example 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9 may be present, with correspondingly different ratios between the incident angle spectrum and the image-side numerical aperture of the projection objective.

A numerical aperture (NA = nsinα, with n: refractive index, z. B. of purge gas, α: half image-side opening angle of the lens) according to claim 16 allows a good spatial resolution of the projection lens. The difference between a largest and a smallest angle of incidence of imaging rays on one of Mirror of the projection objective is preferably not more than 0.9 arcsin (NA), more preferably at most 0.8 arcsin (NA) and even more preferably at most 0.7 arcsin (NA).

A Field size according to claim 17 allows a good throughput in the operation of a projection exposure system with such a projection lens.

One Incidence angle according to claim 18 allows the use a reflection mask, on which the with the projection lens is to be imaged structure. The angle of incidence is in particular 6 °.

The Advantages of a projection exposure apparatus according to claim 19, a A manufacturing method according to claim 20 and a microstructured one Component according to claim 21 correspond to those above with reference to the projection lens according to the claims 1 to 19 have already been explained.

embodiments The invention will be described below with reference to the drawing explained. In this show:

1 schematically a projection exposure system for microlithography;

2 an exemplary imaging beam paths containing Meridionalschnitt by an embodiment of a projection optics of the projection exposure system according to 1 ;

3 one too 2 similar representation of another embodiment of a projection optics;

4 one too 2 similar representation of another embodiment of a projection optics;

5 one too 2 similar representation of another embodiment of a projection optics; and

6 schematically a projection exposure system with the projection optics according to 5 ,

A projection exposure machine 1 for microlithography has a light source 2 for illumination light 3 , At the light source 2 It is an EUV light source that generates light in a wavelength range between 5 nm and 30 nm. Other EUV wavelengths are possible. Alternatively, the projection exposure system 1 also for example with illumination light 3 with visible wavelengths, UV wavelengths, DUV wavelengths or VUV wavelengths. A beam path of the illumination light 3 is in the 1 shown very schematically.

For guiding the illumination light 3 towards an object field 4 in an object plane 5 serves a lighting optics 6 , With a projection optics 7 in the form of a projection lens, the object field becomes 4 in a picture field 8th in an image plane 9 mapped with a given reduction scale. This reduction scale is 4: 1. The projection optics 7 thus reduces the size of the object field 4 towards the picture field 8th by a factor of 4.

The projection optics 7 For example, it reduces the size by a factor of 4. Other magnifications are also possible, for example 5x, 6x, 8x, or even magnifications greater than 8x. Also image scales smaller than 4x are possible.

The picture plane 9 is parallel to the object plane 5 arranged. Here, one is shown with the object field 4 coincident clipping of the reflection mask 10 , The image is taken on the surface of a substrate 11 in the form of a wafer made by a substrate holder 12 worn.

To facilitate the description of positional relationships, an xyz coordinate system is used in the drawing. The x-axis runs in the 1 perpendicular to the drawing plane and away from the viewer into it. The y-axis runs in the 1 to the right. The z-axis runs in the 1 downward.

The reflection mask 10 , which is held by a reticle holder, not shown, and the substrate 11 are scanned in the y-direction in the projection exposure synchronized with each other.

2 shows a first embodiment of an optical design for the projection optics 7 , Shown is the course of individual imaging beams 13 of the illumination light 3 which emanate from two spaced field points. Shown as one of the picture rays 13 is also the main ray of the central field point, ie the main ray of the field point, which is exactly at the intersection of the corners of the object field 4 or the image field 8th connecting diagonals lies.

In the projection optics 7 is the picture plane 9 the first field level of the projection optics 7 after the object plane 5 , The projection optics 7 thus has no intermediate image plane.

The projection optics 7 has a picture-side numerical aperture of 0.25. A length T, ie the distance between the object plane 5 and the picture plane 9 the projection optics 7 is 1585 mm.

In principle possible, but not shown embodiments of projection optics, in which the object plane 5 not parallel to the picture plane 9 is arranged, the length T is defined as the distance of a central object field point to the image plane. In an equally possible, but not shown projection lens with an odd number of mirrors, for example with seven or nine mirrors, the length is defined as the maximum distance between one of the mirrors and one of the field levels.

An object-image offset d _{OIS of} the projection optics 7 is 1114.5 mm. The object-image offset d _OIS is defined as the distance between a vertical projection P of a central object field point on the image plane 8th and the central pixel.

The relationship between the length T and the object-image offset d _OIS is in the projection optics after 2 therefore about 1.42.

The field size of the projection lens 7 is in the picture plane 9 2 mm in the y direction and 26 mm in the x direction and in the object plane 5 8 mm in the y direction and 108 mm in the x direction.

The object field 4 and the picture box 8th are rectangular. In principle, the fields can also be partial-ring-shaped with a corresponding xy-aspect ratio, ie they can also be present as curved fields.

The y-dimension of the fields is also called slot height and the x dimension referred to as slot width.

An incident angle β of the imaging rays 13 on the object field 4 , so on the reflection mask 10 , is 6 °. Other angles of incidence β are possible.

The projection optics 7 has a total of six mirrors M1, M2, M3, M4, M5, M6, which, starting from the object field 4 in the order of exposure to the illumination light 3 numbered. Mirrors M3 and M6 are concave. The mirror M4 is convex. Shown in the 2 only the reflecting surfaces of the mirrors M1 to M6, but not the entire mirror body or associated mounts.

The mirrors M1 to M6 are illuminated with the illumination light 3 each acted upon by an incident angle spectrum. This incident angle spectrum is the difference between a smallest angle of incidence α _min and a maximum angle of incidence α _max on the respective mirror M1 to M6. this is the 2 shown on the example of the penultimate mirror M5, the absolute largest incidence angle spectrum of the projection optics 7 having.

The following table shows the incident angle spectrum α _max - α _min for the mirrors M1 to M6: mirror α _max - α _min M1 4.4 ° M2 5.5 ° M3 2.3 ° M4 2.2 ° M5 10 ° M6 9.6 °

I'm in the 2 shown meridional section occurs the smallest angle of incidence α _min on the mirror M5 at its right edge and is about 14 °. The largest angle of incidence α _max occurs in the 2 at the left edge of the mirror M5 and is about 24 °. The mirror M5 thus has an incident angle spectrum of 10 °. This incident angle spectrum simultaneously represents the largest angle of incidence difference at one of the mirrors M1 to M6.

The angles of incidence on the mirrors M1 to M6 of the projection optics 7 Therefore, they move almost exclusively in a range in which the approximation of small angles (0 ° ≤ α ≤ 7 °) is very well satisfied. The mirrors M1 to M6 are therefore coated in each case over their entire reflection surface with a reflection coating with a uniform thickness.

The reflection coating is, in particular, a multilayer coating, that is to say a layer stack of alternating molybdenum and silicon layers, as is known for EUV reflection coatings. Due to the small maximum incident angle spectrum of only 10 ° it is ensured that the reflection on all mirrors M1 to M6 of the projection optics 7 over the entire mirror surface to a good approximation is constant. An undesired reflection course over the respective mirror surface or an undesirably large apodization occurs in the projection optics 7 therefore not on. The apodization is defined as the variation of the intensity distribution of the illumination light 3 over the pupil. When as I _max the maximum intensity of the illumination light 3 in a pupil plane of the projection optics 7 and as I _min the minimum intensity of the illumination light 3 is denoted by this pupil level, for example, is the value A = (I Max - I min ) / I Max a measure of apodization.

At least one of the mirrors M1 to M6 has a reflection surface, which is designed as a free-form reflection surface with a biconical basic shape and can be described by the following surface formula:

x and y denote the coordinates on the reflection surface, starting from a coordinate origin, called the puncture point a normal is defined by the reflection surface. This puncture point can theoretically also outside lie the used reflection surface.

z denotes the arrow height of the free-form reflecting surface. The coefficients cvx and cvy describe the curvatures the free-form reflection surface in the xz and yz sections. The coefficients ccx and ccy are conic parameters.

The Free-form surface formula has a leading biconical Term and a subsequent xy polynomial with coefficients.

With the following tables, the arrangement and shape of the optical surfaces of the mirrors M1 to M6 within the projection optics 7 specified.

The Table 1 defines selected surfaces in the first column as numbers. In the second column, the distance of the respective Surface to the next surface indicated in z-direction. The third column of Table 1 gives a y decentration of the local coordinate system of the respective surface with respect to a global coordinate system.

The last column of Table 1 allows an assignment of the defined surfaces to the components of the projection optics 7 , surface Distance to previous surface y decentration 0 0.000000 0 image plane 1 708.322803 0 2 -617.533694 -91.468948 M6 3 583.375491 -91.682056 M5 4 -593.218566 -91.059467 M4 5 648.730180 -155.250886 M3 6 -403.572644 -96.008370 M2 7 674.571026 -73.556295 M1 8th 0.000000 -656.479198 object level Table 1

Table 2 gives the data on the respective free-form reflecting surfaces of mirrors M6 (surface 2), M5 (surface 3), M4 (surface 4), M3 (surface 5), M2 (surface 6) and M1 (surface 7). Unspecified coefficients are equal to zero. In addition: RDX = 1 / cvx; RDY = 1 / cvy. Free-form data surface 2 RDY -970.864728 RDX -994.977890 CCY 0.433521 CCX 0.477907 j i - j _{aj, ij} 0 1 -1,160933E-03 2 0 -2,807756E-05 0 2 -2,400704E-05 2 1 -2,727535E-10 0 3 -1,561712E-09 surface 3 RDY -859.920276 RDX -909.711920 CCY 2.066084 CCX 2.157360 j i - j _{aj, ij} 0 1 -6,956243E-03 2 0 4,069558E-04 0 2 4,110308E-04 2 1 -1,135961E-08 0 3 -3,068762E-08 surface 4 RDY 2123.400000 RDX 1668.900000 CCY 11.575729 CCX 7.435682 j i - j _{aj, ij} 0 1 1,393833E-01 2 0 3,570289E-04 0 2 4,726719E-04 2 1 4,922014E-08 0 3 1,301911E-09 surface 5 RDY 1292.100000 RDX 1411.600000 CCY -0.067691 CCX 0.332429 j i - j _{aj, ij} 0 1 2,827164E-03 2 0 3,218435E-05 0 2 6,355344E-07 2 1 3,212318E-09 0 3 3,463152E-09 surface 6 RDY -2,615.500000 RDX -11,975.000000 CCY 0.354474 CCX 58.821858 j i - j _{aj, ij} 0 1 -1,510373E-01 2 0 2,929133E-04 0 2 3,971921E-04 2 1 -2,211237E-08 0 3 2,084484E-08 surface 7 RDY 171.052222 RDX 507.844993 CCY -1.000256 CCX -1.006263 j i - j _{aj, ij} 0 1 1,224307E-02 2 0 -7,916373E-04 0 2 -2,757507E-03 2 1 -3,313700E-08 0 3 -7,040288E-09 Table 2

3 shows a further embodiment of a projection optics 14 that instead of the projection optics 7 at the projection exposure machine 1 to 1 can be used. Components of the projection optics 14 corresponding to those described above with reference to the projection optics 7 already described, bear the same reference numbers and will not be discussed again in detail.

The projection optics 14 has a picture-side numerical aperture of 0.25. The length T of the projection optics 14 is 1000 mm. The object-image offset d _OIS is in the projection optics 14 656.5 mm. The ratio T / d _OIS is therefore about 1.52.

The maximum incident angle spectrum is also in the projection optics 14 at the mirror M5 before and is there 12 °. The minimum angle of incidence is at the mirror M5 in the 3 right edge in front and is about 6 °. The maximum angle of incidence is on the mirror M5 in the 3 on the left edge and is about 18 °. Also with the projection optics 14 is the picture plane 9 the first field level after the object plane 5 ,

Also with the projection optics 14 At least one of the mirrors M1 to M6 is designed as a biconical free-form reflecting surface.

With the following tables, the arrangement and shape of the optical surfaces of the mirrors M1 to M6 within the projection optics 14 specified.

The Table 3 defines selected surfaces in the first column as numbers. In the second column, the distance of the respective Surface to the next surface indicated in z-direction. The third column of Table 3 gives a y decentration of the local coordinate system of the respective surface with respect to a global coordinate system.

The last column of Table 3 allows an assignment of the defined surfaces to the components of the projection optics 14 , surface Distance to previous surface y decentration 0 0.000000 0 image plane 1 636.883689 0 2 -584.268871 -127.232050 M6 3 649.268844 -127.625397 M5 4 -689.518581 -127.310875 M4 5 635.140406 -214.759354 M3 6 -438.983578 -160.525812 M2 7 792.496449 -161.853347 M1 8th 0.000000 -978.074419 object level Table 3

Table 4 gives the data on the respective free-form reflecting surfaces of mirrors M6 (surface 2), M5 (surface 3), M4 (surface 4), M3 (surface 5), M2 (surface 6) and M1 (surface 7). Unspecified coefficients are equal to zero. In addition: RDX = 1 / cvx; RDY = 1 / cvy. Free-form data surface 2 RDY -1,024.300000 RDX -1,051.200000 CCY 0.715756 CCX 0.739924 ^j i - j _{aj, ij} 0 1 -7,576779E-04 2 0 -3,738732E-05 0 2 -4,247383E-05 2 1 9,295774E-10 0 3 -2,890724E-09 4 0 -7,975116E-13 2 2 -5,165327E-12 0 4 3,661841E-13 4 1 -7,996231E-16 2 3 2,111768E-15 0 5 -1,722248E-15 6 0 -5,045304E-19 4 2 5,124801E-18 2 4 6,369116E-18 0 6 -1,032383E-18 surface 3 RDY -1,035.900000 RDX -1,101.300000 CCY 2.617124 CCX 2.951155 ^j i - j _{aj, ij} 0 1 -2,179019E-03 2 0 4,431389E-04 0 2 4,560760E-04 2 1 -1,644268E-08 0 3 -2,950490E-08 4 0 2,263165E-11 2 2 1,778578E-11 0 4 1,964554E-12 4 1 1,279827E-14 2 3 6,648394E-14 0 5 -2,265488E-14 6 0 2,095952E-17 4 2 4,287989E-17 2 4 -1,642439E-17 0 6 -2,118969E-17 surface 4 RDY 1665.900000 RDX 1372.000000 CCY 9.138623 CCX 1.926620 j i - j _{aj, ij} 0 1 2,014437E-01 2 0 2,109164E-04 0 2 4,684147E-04 2 1 1,447739E-09 0 3 3,484838E-09 4 0 -1,165581E-24 2 2 4,175896E-13 0 4 7,119405E-12 4 1 5,269322E-14 2 3 -2,420761E-14 0 5 -2,012170E-14 6 0 -3,454027E-16 4 2 1,557629E-16 2 4 -1,050420E-15 0 6 -2,742748E-17 surface 5 RDY 1238.200000 RDX 1414.200000 CCY -0.000012 CCX 0.119482 j i - j _{aj, ij} 0 1 1,047982E-02 2 0 2,196150E-05 0 2 7,186632E-07 2 1 4,040466E-09 0 3 9,100125E-09 4 0 5,634656E-12 2 2 -2,298266E-14 0 4 -4,645176E-13 4 1 9,046464E-16 2 3 -2,605868E-16 0 5 -1,673891E-15 6 0 -2,618503E-18 4 2 4,839689E-18 2 4 -6,947211E-18 0 6 -4,314040E-18 surface 6 RDY -3,684.400000 RDX -3,506.300000 CCY -0.001235 CCX 0.415150 j i - j _{aj, ij} 0 1 -1,767860E-01 2 0 5,073838E-04 0 2 5,272916E-04 2 1 -3,957421E-08 0 3 8,058238E-09 4 0 7,959552E-25 2 2 -7,112502E-13 0 4 6,827653E-13 4 1 -2,253930E-13 2 3 1,303253E-13 0 5 1,567942E-15 6 0 -2,326019E-16 4 2 -2,314170E-16 2 4 1,309455E-16 0 6 -5,879379E-18 surface 7 RDY 167.705178 RDX 408.126726 CCY -1.001961 CCX -0.994641 ^j i - j _{aj, ij} 0 1 -2,378224E-04 2 0 -1,003186E-03 0 2 -2,870643E-03 2 1 -3,511331E-09 0 3 -1,211650E-07 4 0 -7,010621E-11 2 2 -5,812898E-12 0 4 -4,637999E-13 4 1 -1,913197E-13 2 3 6,243649E-16 0 5 4,280774E-16 6 0 -5,399656E-17 4 2 -1,237113E-16 2 4 1,580174E-19 0 6 6,222451E-19 Table 4

4 shows a further embodiment of a projection optics 15 that instead of the projection optics 7 at the projection exposure machine 1 to 1 can be used. Components of the projection optics 15 corresponding to those described above with reference to the projection optics 7 already described, bear the same reference numbers and will not be discussed again in detail. The projection optics 15 has a picture-side numerical aperture of 0.32. The length T of the projection optics 15 is 1000 mm. The object-image offset d _OIS is in the projection optics 15 978 mm. The ratio T / d _OIS is therefore about 1.02.

The maximum incident angle spectrum is also in the projection optics 15 at the mirror M5 before and is there 13 °. The minimum angle of incidence is at the mirror M5 in the 4 right edge in front and is about 9 °. The maximum angle of incidence is on the mirror M5 in the 4 at the left edge and is about 22 °. Also with the projection optics 15 is the picture plane 9 the first field level after the object plane 5 ,

Also with the projection optics 15 At least one of the mirrors M1 to M6 is designed as a biconical free-form reflecting surface.

With the following tables, the arrangement and shape of the optical surfaces of the mirrors M1 to M6 within the projection optics 15 specified.

The Table 5 defines selected surfaces in the first column as numbers. In the second column, the distance of the respective Surface to the next surface indicated in z-direction. The third column of Table 5 gives a y decentration of the local coordinate system of the respective surface with respect to a global coordinate system.

The last column of Table 5 allows an assignment of the defined surfaces to the components of the projection optics 15 , surface Distance to previous surface y decentration 0 0.000000 0.000000 image plane 1 726.023335 0.000000 2 -577.595015 -192.238869 M6 3 745.417411 -192.777551 M5 4 -738.103985 -192.462469 M4 5 994.730526 -243.767917 M3 6 -450.919688 -164.949143 M2 7 885.694809 -165.918838 M1 8th 0.000000 -1,114.493643 object level Table 5

Table 6 gives the data on the respective free-form reflecting surfaces of mirrors M6 (surface 2), M5 (surface 3), M4 (surface 4), M3 (surface 5), M2 (surface 6) and M1 (surface 7). Unspecified coefficients are equal to zero. In addition: RDX = 1 / cvx; RDY = 1 / cvy. Free-form data surface 2 RDY -1,172.300000 RDX -1,295.000000 CCY 0.787469 CCX 1.053600 j i - j _{aj, ij} 0 1 -7,219074E-04 2 0 -3,578974E-05 0 2 -2,128273E-05 2 1 7,097815E-10 0 3 -1,618913E-09 4 0 -2,252005E-12 2 2 -3,895991E-12 0 4 2,750606E-13 4 1 -4,464498E-15 2 3 -4,637860E-16 0 5 -6,920120E-16 6 0 -3,637297E-18 4 2 2,537830E-18 2 4 1,002850E-17 0 6 -3,044197E-18 surface 3 RDY -1,236.400000 RDX -1,536.200000 CCY 2.551177 CCX 4.047183 j i - j _{aj, ij} 0 1 -6,558677E-03 2 0 3,540129E-04 0 2 4,133618E-04 2 1 -1,904320E-08 0 3 -3,576692E-08 4 0 1,496417E-12 2 2 1,864663E-11 0 4 3,000005E-12 4 1 -7,105811E-15 2 3 5,293727E-14 0 5 -1,509974E-14 6 0 2,907360E-18 4 2 5,694619E-17 2 4 8,177232E-17 0 6 4,847943E-18 surface 4 RDY 2267.500000 RDX 1709.200000 CCY 13.716154 CCX 2.188445 j i - j _{aj, ij} 0 1 2,536301E-01 2 0 1,786226E-04 0 2 4,303983E-04 2 1 -5,494928E-10 0 3 4,116436E-09 4 0 -2,775915E-11 2 2 3,269596E-11 0 4 3,121929E-12 4 1 2,286620E-14 2 3 1,431437E-14 0 5 -8,016660E-15 6 0 -8,966865E-17 4 2 3,631639E-16 2 4 -3,150250E-16 0 6 -7,235944E-18 surface 5 RDY 1453.100000 RDX 1691.600000 CCY 0.004158 CCX 0.130787 j i - j _{aj, ij} 0 1 1,413720E-02 2 0 1,853431E-05 0 2 8,632041E-07 2 1 2,471907E-09 0 3 1,031600E-08 4 0 1,594814E-12 2 2 1,271047E-13 0 4 -8,477699E-14 4 1 1,841514E-15 2 3 1,063273E-15 0 5 -3,890516E-16 6 0 -7,937130E-19 4 2 4,923627E-18 2 4 -3,489821E-18 0 6 -3,625541E-18 surface 6 RDY -3,061.000000 RDX -3,961.700000 CCY 0.069638 CCX 0.416068 j i - j _{aj, ij} 0 1 -1,950186E-01 2 0 4,908498E-04 0 2 5,948960E-04 2 1 -2,711540E-08 0 3 1,073427E-08 4 0 -3,053221E-12 2 2 -5,601149E-12 0 4 4,072326E-13 4 1 -3,675214E-13 2 3 3,165916E-14 0 5 -1,649353E-15 6 0 -8,908751E-17 4 2 -2,427088E-16 2 4 2,643106E-16 0 6 -7,400900E-18 surface 7 RDY 210.148013 RDX 383.382688 CCY -1.001702 CCX -0.999069 ^j i - j _{aj, ij} 0 1 -2,506963E-04 2 0 -1,093695E-03 0 2 -2,285463E-03 2 1 -7,246135E-09 0 3 -1,030905E-07 4 0 -7,535621E-11 2 2 -4,600461E-12 0 4 -9,217052E-14 4 1 -2,057821E-13 2 3 2,433632E-16 0 5 1,627316E-16 6 0 -1,969282E-17 4 2 -1,033559E-16 2 4 2,086873E-17 0 6 1,058816E-18 Table 6

5 shows a further embodiment of a projection optics 16 that instead of the projection optics 7 at the projection exposure machine 1 to 1 can be used. Components of the projection optics 16 corresponding to those described above with reference to the projection optics 7 already described, bear the same reference numbers and will not be discussed again in detail.

The projection optics 16 has a picture-side numerical aperture of 0.35. the length T of the projection optics 16 is 1500 mm. The object-image offset d _OIS is 580 mm in the projection optics 16 , The ratio T / d _OIS is therefore about 2.59.

On the mirror M5 of the projection optics 16 There is a minimum angle of incidence of 0.15 ° and a maximum angle of incidence of 23.72 °. The angle of incidence spectrum on the M5 mirror is therefore 23.58 ° and is the largest angle of incidence spectrum on the mirrors of the projection optics 16 ,

The projection optics 16 has an intermediate image plane between the mirrors M4 and M5 17 , This is approximately where the imaging rays 13 be passed by the mirror M6.

wobei gilt:

The free-form reflecting surfaces of the mirrors M1 to M6 of the projection optics 16 can be mathematically described by the following equation:

where:

Z is the arrow height of the freeform surface at point x, y (x ² + y ² = r).

c is a constant corresponding to the vertex curvature of a corresponding asphere. k corresponds to a conical constant of a corresponding asphere. C _j are the coefficients of the monomials X ^m Y ⁿ . Typically, the values of c, k and C _{j will be} based on the desired optical properties of the mirror within the projection optics 16 certainly. The order of the monomial, m + n, can be varied as desired. A higher-order monomode can lead to a design of the projection optics with better image aberration correction, but is more expensive to compute. m + n can take values between 3 and more than 20.

Free-form surfaces can also be mathematically described by Zernike polynomials, which are explained in the manual of the optical design program CODE V ^® , for example. Alternatively, freeform surfaces can be described using two-dimensional spline surfaces. Examples include Bezier curves or non-uniform rational base splines (NURBS). For example, two-dimensional spline surfaces may be described by a network of points in an xy plane and associated z-values or by these points and their associated slopes. Depending on the particular type of spline surface, the complete surface is obtained by interpolating between the mesh points using e.g. As polynomials or functions that have certain properties in terms of their continuity and differentiability won. Examples of this are analytical functions.

The optical design data of the reflection surfaces of the mirrors M1 to M6 of the projection optics 7 can be found in the following tables. The first of these tables indicates, in each case, the reciprocal of the vertex curvature (radius) and a thickness value (thickness) corresponding to the z-spacing of adjacent elements in the beam path, starting from the object plane, to the optical surfaces of the optical components and to the aperture stop. The second table gives the coefficients C _{j of} the monomials X ^m Y ⁿ in the free-form surface equation given above for the mirrors M1 to M6. Nradius is a scaling factor. After the second table is still the amount in mm, along which the respective mirror, based on a mirror reference design decentered (Y-decenter) and twisted (X-rotation) was. This corresponds to the parallel displacement and the tilt in the free-form surface design method described above. It is shifted in the y-direction and tilted about the x-axis. The twist angle is given in degrees. surface radius distance operation mode object level INFINITE 727.645 Mirror 1 -1,521.368 -420.551 REFL Mirror 2 4501.739 540.503 REFL Mirror 3 501.375 -313.416 REFL Mirror 4 629.382 868.085 REFL Mirror 5 394.891 -430.827 REFL Mirror 6 527.648 501.480 REFL image plane INFINITE 0,000 coefficient M1 M2 M3 M4 M5 M6 K -6,934683E + 00 -1,133415E + 02 -4,491203E + 00 2,864941E-01 6,830961E + 00 8,266681E-02 Y 0,000000E + 00 0,000000E + 00 0,000000E + 00 0,000000E + 00 0,000000E + 00 0,000000E + 00 X2 -1,784786E-04 -1,625398E-04 -4,091759E-04 -1,283213E-05 1,852188E-04 1,527974E-06 Y2 -1,924874E-04 -2,007476E-04 -4,089273E-04 -3,385713E-05 1,462618E-04 1,999354E-06 X 2 Y 7,567253E-08 3,033726E-07 4,563127E-07 3,550829E-08 2,779793E-07 6,063643E-10 Y3 4,318244E-08 4,548440E-09 -4,162578E-08 -2,113434E-08 6,705950E-07 5,861708E-09 X4 -4,430972E-10 -1,014203E-09 4,055457E-09 -6,220378E-11 -8,891669E-10 -1,395997E-11 X2Y2 -8,520546E-10 -6,881264E-10 8,939911E-09 -1,392199E-10 5,141975E-09 -1,167067E-11 Y4 -4,543477E-10 9,382921E-10 5,474325E-09 -6,995794E-11 5,400196E-10 3,206239E-12 X4Y -2,099305E-14 -4,394241E-13 -5,095787E-12 -1,116149E-14 -3,574353E-13 5,504390E-15 X2Y3 -9,594625E-14 -5,563377E-12 -2,467721E-12 1,007439E-14 1,351005E-11 1,988648E-14 Y5 -6,552756E-13 -1,586808E-11 3,433129E-11 1,283373E-12 5,833169E-11 8,273816E-15 X6 -5,518407E-17 -4,175604E-15 -2,733992E-14 -9,578075E-17 -7,907746E-14 -2,844119E-17 X4Y2 1,982470E-16 5,202976E-15 -3,722675E-14 1,225726E-16 2,278266E-14 -2,154623E-17 X2Y4 3,530434E-16 2,469563E-14 -2,047537E-13 -1,207944E-15 2,530016E-13 2,350448E-18 Y6 1,142642E-15 2,708016E-14 -7,131019E-34 1,880641E-14 1,622798E-13 -9,962638E-18 X6Y -6,790512E-20 -1,328271E-17 -2.926272E - 16 -2,248097E-19 -4,457988E-16 8,532237E-21 X4Y3 -6.322471E - 19 3,908456E-17 -2,737455E-16 -7,629602E-20 1,416184E-15 3,243375E-20 X2Y5 -1,195858E-17 -5,908420E-17 6,146576E-15 1,102606E-16 3,414825E-15 -2,740056E-21 Y7 2,350101E-17 -1,477424E-15 5,232866E-14 1,218965E-15 1,819850E-15 -1,903739E-19 X8 -6,917298E-22 8,248359E-20 6,770710E-19 9,667078E-22 -3,953231E-39 -4,407667E-23 X6Y2 -4,633739E-22 1,268409E-19 -1,035701E-10 -6,006155E-20 2,725218E-38 -6,933821E-23 X4Y4 -1,497254E-20 -1,719209E-18 -3,217683E-18 -1,742201E-20 -1,679944E-39 4,964397E-23 X2Y6 -3,969941E-20 -3,497307E-18 4,228227E-17 -2,656234E-18 4,611895E-18 1,663632E-22 Y8 6,708554E-20 1,187270E-18 2,685040E-38 -1,611964E-39 4,730942E-18 6,011162E-23 X8Y -4,466562E-24 3,597751E-23 2,879249E-20 -1,588496E-23 -5,662885E-20 5,805689E-26 X6Y3 2,874487E-23 1,003878E-20 6,793162E-20 3,438183E-23 -1,071225E-20 -1,310631E-25 X4Y5 2,249612E-23 1,390470E-20 1,950655E-19 1,008316E-21 -6,062162E-20 -3,380438E-25 X2Y7 5,258895E-22 2,194560E-20 -2,724912E-18 -3,405763E-20 -1,780372E-19 1,649113E-25 Y9 -4,497858E-21 2,311634E-19 -2,656603E-17 -3,124398E-19 -1,417439E-19 2,296226E-24 X10 0,000000E + 00 -6,351950E-24 -8,560053E-23 -4,339912E-26 -8,430614E-22 -3,388610E-28 X8Y2 0,000000E + 00 4,523937E-24 9,792140E-22 2,952972E-24 9,614763E-23 1,083831E-27 X6Y4 0,000000E + 00 -9,774541E-23 -2,428620E-21 -5,303412E-24 -1,020095E-22 3,199302E-27 X4Y6 0,000000E + 00 4,704150E-23 1,195308E-42 2,279968E-23 -6,658041E-23 1,968405E-27 X2Y8 0,000000E + 00 1,270549E-22 1,329832E-41 8,858543E-22 5,185397E-22 3,257732E-28 Y10 0,000000E + 00 -1,244299E-21 -8,254524E-44 -6,003123E-22 5,204197E-23 1,473250E-27 NRadius 1,000000E + 00 1,000000E + 00 1,000000E + 00 1,000000E + 00 1,000000E + 00 1,000000E + 00 coefficient M1 M2 M3 M4 M5 M6 image Y-decentering 37.685 -15.713 -139.004 -151.477 -395.184 -440.921 0,000 X rotation 0.326 -3.648 -5.539 -5.647 4,878 5.248 0,000

In the 5 is with the reference number 18 denotes a main ray belonging to a central object field point. With 19 is in the 5 a normal to the object plane 5 denoted by the central object field point. In the object plane 5 So cut the main beam 18 and the normals 19 , Along the further beam path of the main beam 18 between the object plane 5 and the picture plane 9 increases the distance of the main beam 18 to the normal 19 monotone. When passing the main beam 18 through the picture plane 9 , ie in the central image field point, this distance is identical to the object image offset d _OIS . The monotone enlargement of the distance of the main ray 18 from the normal 19 in the beam path between the object plane 5 and the picture plane 9 means that this distance along the course of the beam path is nowhere smaller. In the projection optics 16 this distance will be until the impact of the main beam 18 on the last mirror M6 steadily bigger. Between the point of impact of the main ray 18 on the mirror M6 and the image plane 9 this distance remains constant.

6 shows in a comparison to 1 less schematic representation of the use of projection optics 16 in the projection exposure machine 1 , Components corresponding to those described above with reference in particular to 1 and 5 already described, bear the same reference numbers and will not be discussed again in detail.

That from the light source 2 emitted illumination light 3 is first of a in the 6 schematically illustrated collector 20 collected.

In contrast to the representation after 1 is in the presentation after 6 the light source 2 represented on a level which in the 6 below the level of the image plane 9 lies. That from the collector 20 collected illumination light 3 must therefore be on the substrate holder 12 be passed.

The illumination optics 6 includes in the execution after 6 one to the collector 20 Subordinate field facet mirror 21 and a pupil facet mirror following this 22 , About the two facet mirrors 21 . 22 there is a defined specification of an intensity distribution and an illumination angle distribution of the illumination light 3 over the object field 4 , Between the collector 20 and the field facet mirror 21 is an intermediate focus 23 in the beam path of the illumination light 3 , The large object-image offset d _{OIS of} the projection optics 16 after the 5 and 6 causes the beam path between the collector 20 and the field facet mirror 21 normal to the object plane 5 and the picture plane 9 , that is vertically, can run. Unnecessarily large angles of incidence on the illuminating light 3 leading mirrors can therefore be avoided without the passage of the illumination light 3 on the substrate holder 12 would be problematic.

The projection optics 7 . 14 . 15 and 16 have as mirror-guiding components only mirrors. So these are mirror projection lenses.

For producing a microstructured component with the aid of the projection exposure apparatus 1 First, the reflection mask 10 and the substrate 11 provided. Subsequently, a structure on the reflection mask 10 with the projection optics 7 the projection exposure system 1 on a photosensitive layer on the wafer 11 projected. Development of the photosensitive layer then results in a microstructure on the wafer 11 and from this creates the microstructured component.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6266389 B1 [0002]
• US 2005/0134980 A1 [0002]
• US 2007/0195317 A1 [0002]
• US 2007/0058269 A1 [0002]
• US 2007/0223112 A [0002]
• - US 6396067 B1 [0002]
• - US 6361176 B1 [0002]
• - US 6666560 B2 [0002]

Claims (21)

Projection lens ( 7 ; 14 ; 15 ) for microlithography for imaging an object field ( 4 ) in an object plane ( 5 ) in an image field ( 8th ) in an image plane ( 9 ) - having at least six mirrors (M1 to M6), of which at least one mirror has a free-form reflecting surface, - wherein the ratio of a length (T) of the projection lens ( 7 ; 14 ; 15 ) and an object-to-image offset (d _OIS ) is less than 12. Projection lens ( 7 ; 14 ; 15 ) for microlithography for imaging an object field ( 4 ) in an object plane ( 5 ) in an image field ( 8th ) in an image plane ( 9 ) - having at least six mirrors (M1 to M6), of which at least one mirror has a free-form reflection surface, - wherein the image plane ( 9 ) the first field plane of the projection objective ( 7 ; 14 ; 15 ) according to the object level ( 5 ). Projection objective according to Claim 1 or 2, characterized by a ratio of an overall length (T) and an object image offset (d _OIS ) which is less than 5. Projection objective according to one of the claims 1 to 3, characterized in that the free-form reflecting surface is designed as a biconical surface. Projection lens ( 7 ; 14 ; 15 ) for microlithography for imaging an object field ( 4 ) in an object plane ( 5 ) in an image field ( 8th ) in an image plane ( 9 ) - having a plurality of mirrors (M1 to M6), characterized by a ratio of a construction length (T) and an object image offset (d _OIS ), which is smaller than 2. Projection lens according to claim 5, characterized by at least six mirrors (M1 to M6). Projection objective according to claim 5 or 6, characterized in that at least one of the mirrors (M1 to M6) has a Free-form reflecting surface has. Projection objective according to Claim 7, characterized that the freeform reflective surface as a biconical surface is trained. Projection objective according to one of claims 5 to 8, characterized in that the image plane ( 9 ) the first field plane of the projection objective ( 7 ; 14 ; 15 ) according to the object level ( 5 ). Projection lens ( 16 ) for microlithography for imaging an object field ( 4 ) in an object plane ( 5 ) in an image field ( 8th ) in an image plane ( 9 ) - with a plurality of mirrors (M1 to M6), of which at least one mirror has a free-form reflection surface, - with at least one intermediate image plane ( 17 ) between the object plane ( 5 ) and the image plane ( 9 ), - wherein the ratio of a length (T) of the projection lens ( 16 ) and an object-to-image offset (d _OIS ) is less than 12. Projection objective according to Claim 10, characterized by a ratio of an overall length (T) and an object image offset (d _OIS ) which is less than 5. Projection objective according to claim 10 or 11, characterized in that the free-form reflection surface according to the surface equation:

is writable, where:

Z: Arrow height of the free-form surface at the point x, y (x ² + y ² = r), c: Constant corresponding to the vertex curvature of a corresponding asphere, k: constant of a corresponding asphere, C _j : coefficients of the monomials X ^m Y ⁿ . Projection objective according to one of claims 1 to 12, characterized in that the distance between - a main beam ( 18 ) to a central object field point and - a normal passing through the central object field point ( 19 ) to the object level ( 5 ) along an optical path of the main beam ( 18 ), from the object field ( 5 ) and down to the image field ( 9 ), increases monotonously. Projection objective according to one of Claims 1 to 13, characterized by an object-to-image offset (d _OIS ) which is greater than 200 mm. Projection objective according to one of claims 1 to 14, characterized in that the ratio of a difference between a maximum (α _max ) and a smallest (α _min ) angle of incidence of imaging beams ( 13 ) on one side of the mirrors (M1 to M6) and on the other hand a picture-side numerical aperture of the projection lens is on the other hand a maximum of 60 °. Projection objective according to one of the claims 1 to 15, characterized by a picture-side numerical aperture of at least 0.25. Projection objective according to one of Claims 1 to 16, characterized by a field size of the object field ( 4 ) and / or the image field ( 8th ) of at least 2 mm × 26 mm. Projection objective according to one of Claims 1 to 17, characterized by an angle of incidence (β) of an imaging beam associated with a central objective field point ( 13 ) on the object field ( 4 ) in the range between 5 ° and 9 °. Projection exposure apparatus ( 1 ) with a light source ( 2 ), an illumination optics ( 6 ) and a projection optics ( 7 ; 14 . 15 ) according to any one of claims 1 to 18. Process for the production of a microstructured component with the following process steps: - Provision of a reticle ( 10 ) and a wafer ( 11 ), - projecting a structure on the reticle ( 10 ) on a photosensitive layer of the wafer ( 11 ) with the aid of the projection exposure apparatus according to claim 19, - production of a microstructure on the wafer ( 11 ). Microstructured component, made after one Method according to claim 20.