US 2007/0165296 A1Published application

Method of designing a projection system, lithographic apparatus and device manufacturing method

AssigneeASML Netherlands B.V.

InventorsFlorian Bociort, Maarten Van Turnhout, Oana Marinescu

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Abstract

Optimization of a projection system is performed to obtain a starting configuration that is at a local minimum of the merit function or simply a previously known minimum system is used as the starting configuration. A zero-thickness meniscus lens is inserted at a surface in the local minimum starting configuration with N surfaces to construct a saddle point with Morse Index=1 having N+2 surfaces. The saddle point is perturbed and optimization is performed on both sides of the saddle, and the distances at the two surfaces that have been introduced are increased, to generate two new configurations, m1 and m2, that are new minima in the merit function. Each resulting configuration is output, e.g., as a table of parameters specifying the projection system or as a computer file for use in making an actual projection system.

Claims27

Dependent claims

A method of designing a projection system for a lithographic projection apparatus, comprising:

obtaining a projection system starting configuration comprising a plurality of surfaces and having a merit function value corresponding to a local minimum in a merit function space;
inserting two additional surfaces at a reference surface in the starting configuration, with a separation between the additional surfaces and between the additional surfaces and the reference surface, with the optical material between the additional surfaces being substantially the same as that at the reference surface and with the curvatures of the two additional surfaces being substantially the same as the curvature of the reference surface to generate a saddle point configuration of a projection system corresponding to a saddle point in merit function space;
perturbing the saddle point configuration and performing optimization on at least one side of the saddle point to obtain a new projection system configuration having a merit function value corresponding to a local minimum in the merit function space;
increasing the separation between the two inserted surfaces and between the inserted surfaces and the reference surface at which they were inserted;
and
outputting the resulting projection system configuration.

3 more elements

A lithographic apparatus projection system comprising a plurality of lenses to be traversed by a beam in sequence, wherein the lenses constitute a sequence of surfaces Si, each surface indicated by a different value of i, each surface separated by a distance Pi from the following surface, wherein the refractive index of the medium following surface Si has the value Ni, wherein each surface has a curvature Qi, and wherein specific ones of the surfaces are further defined by aspheric coefficients Ai, Bi, Ci, Di, Ei, Fi, Gi,

wherein the distance Pi is in the range of from (1−ε1)pi to (1+ε1)pi,
wherein the refractive index Ni is in the range of from (1−ε2)ni to (1+ε2)ni,
wherein the aspheric coefficients Xi are in the range of from (1−ε3)xi to (1+ε3)xi, where X and x indicate the letters A, B, C, D, E, F, G and a, b, c, d, e, f and g respectively,
wherein the curvature Qi is in the range of from (1/ri)−μ to (1/ri)+μ,
where ε1, ε2 and ε3 are each less than or equal to 0.01, where μ is less than or equal to 3×10−2 mm−1, and where the values pi, ni, ri, ai, bi, ci, di, ei, fi, gi are given in the following tables:
Surface
Radius ri
Distance pi
ni
i
(mm)
(mm)
ref. index
Object
Infinity
32
1.000302
1
Infinity
4.9648180901e−016
1.000302
2
898.023859654604
11.4782608731
1.560786
3
134.463937760492
9.48178051201
1.000300
4
279.589510966665
12.1628486499
1.560786
5
429.713386743823
30.5763283345
1.000300
6
−133.575828304914
52.2609104477
1.560786
7
−168.229498108882
1
1.000300
8
−322.654424433578
52.1915639063
1.560786
9
−332.142084551994
1
1.000300
10
487.536690843154
53.4932785237
1.560786
11
−336.595124657592
8.83282118993
1.000300
12
208.196678465787
55.9584509243
1.560786
13
−2623.49750843192
1
1.000300
14
193.30761811124
52
1.560786
15
155.968334943742
32.9455980804
1.000300
16
−12881.3575310104
12.5915495035
1.560786
17
403.369936634196
38.7100608856
1.000300
18
−105.74885910938
5.65846203479
1.560786
19
167.881505445566
26.2063087045
1.000300
20
−163.085971837724
43.3797347636
1.560786
21
−217.136687224511
7.75348256739
1.000300
22
−797.722656872767
21.7839396346
1.560786
23
207.582687341939
28.5496395352
1.000300
24
−1088.15829228498
36.4121314285
1.560786
25
−181.255482926078
2.87340786737
1.000300
26
298.782208978124
31.8456070276
1.560786
27
1037.54514485231
35.3190829377
1.000300
Stop
Infinity
7.67288412877
1.000300
29
403.195003517407
54.0542249345
1.560786
30
−3049.00018563268
26.0031544427
1.000300
31
1664.90725274904
48.7708456771
1.560786
32
−306.660040565939
0.334832322002
1.000300
33
188.839828069829
46.8455217041
1.560786
34
208.117004701503
2.40815418959
1.000300
35
135.132628439669
46.3838349983
1.560786
36
396.103393693348
1
1.000300
37
116.187821079462
47.8154003025
1.560786
38
201.589370561389
9.00187082814
1.000300
39
536.431565230929
36.6317358331
1.560786
40
820.248661906301
3.20826206953
1.000300
41
Infinity
10
1.560786
42
Infinity
8
1.000302
Image
Infinity
−3.198e−005
ai
bi
ci
i
k
ei
fi
gi
di
2
0
1.827356401e−007
−1.964723247e−011
2.826932271e−015
−3.74016622e−019
3.076574013e−023
−1.219964317e−028
−2.296232868e−031
4
0
8.134674858e−008
1.104556698e−011
−1.685618766e−015
1.87988583e−019
−1.023459956e−023
−4.912925606e−028
1.749013548e−031
17
0
7.319068222e−008
2.110164496e−012
−1.231572849e−016
1.11183883e−019
−4.827860977e−023
1.002154882e−026
−1.010925070e−030
22
0
5.184566313e−008
2.219202716e−012
4.794557685e−017
−2.37716357e−021
5.789862375e−026
−5.785892172e−029
3.675508546e−033
27
0
1.322829666e−008
−2.359107509e−013
−7.418731240e−018
6.10788293e−023
−6.637329327e−027
5.771574474e−031
−1.659844755e−035
30
0
5.200370613e−009
3.266751776e−013
3.648281997e−018
−8.12903873e−023
7.955327013e−027
−3.788219518e−031
7.724948872e−036
39
0
−9.269356549e−008
2.721883131e−012
9.611406529e−016
−3.52824389e−020
−2.306888008e−023
3.782079247e−027
−2.077933409e−031

257 more elements

A lithographic apparatus projection system comprising a plurality of mirrors to be encountered by a beam in sequence, wherein the mirrors constitute a sequence of reflective surfaces Si, each surface indicated by a different value of i, each surface separated by a distance Pi from the following surface, wherein each surface has a curvature Qi, and wherein each surface is further defined by aspheric coefficients Ai, Bi, Ci, Di, Ei,

wherein the distance Pi is in the range of from (1−ε1)pi to (1+ε1)pi,
wherein the aspheric coefficients Xi are in the range of from (1−ε2)xi to (1+ε2)xi, where X and x indicate the letters A, B, C, D, E and a, b, c, d, and e respectively,
wherein the curvature Qi is in the range of from (1/ri)−μ to (1/ri)+μ,
where ε1 and ε2 are each less than or equal to 0.01, where μ is less than or equal to 2×10−3 mm−1, and where the values pi, ri, ai, bi, ci, di, ei are given in one of the following:
tables A1 and A2;
or tables B1 and B2;
or tables C1 and C2
TABLE A1
Radius ri
Distance pi
Surface i
(mm)
(mm)
Object
Infinity
500.8243
1
−412.8448
−145.5591
Stop
−207.5412
205.9176
3
−600.5993
−318.9442
4
−6.8944e+004
610.0009
5
−708.809
−228.2049
6
−1785.61
244.5
7
279.5399
−229.519
8
284.0269
250.0008
Image
Infinity
5.6e−007
TABLE A2
i
k
ai
bi
ci
di
ei
1
−1
−4.7933e−009
4.1498e−014
−1.4112e−019
−9.3179e−024
1.9103e−028
Stop
−1
−9.7923e−009
1.3794e−012
1.3993e−016
9.7324e−020
0
3
−1
−3.0962e−009
−8.41e−016
−3.9728e−020
−8.281e−025
1.0759e−029
4
−1
−4.1446e−009
2.2188e−014
−4.1285e−018
1.162e−022
−2.0614e−027
5
−1
−1.6868e−009
9.5153e−015
−1.2393e−019
5.0798e−025
0
6
−1
−7.4658e−009
−2.3282e−013
9.6627e−018
−3.0365e−022
3.4264e−027
7
−1
9.0763e−008
−2.0467e−012
3.3919e−016
1.1278e−020
−5.5313e−025
8
−1
5.7961e−009
3.9097e−014
3.3856e−019
2.477e−024
5.5432e−029
TABLE B1
Reflective
Radius ri
Distance pi
surface i
(mm)
(mm)
Object
Infinity
629.76
1
−502.31
−192.98
Stop
−443.57
496.91
3
−1194.91
−590.2
4
1174.92
638.2
5
252.84
−304.93
6
379.33
353.24
Image
Infinity
0
TABLE B2
i
k
ai
bi
ci
di
ei
1
−1.0
−8.10492e−10
−2.12812e−15
2.00734e−20
−2.91712e−25
0
Stop
−1.0
2.52722e−08
1.84295e−12
7.68723e−17
1.92816e−20
0
3
−1.0
3.89102e−11
−1.20482e−15
1.71841e−20
−1.06109e−25
0
TABLE C1
Reflective
Radius ri
Distance pi
surface i
(mm)
(mm)
Object
Infinity
599
1
−11649.62807
−420.38
Stop
756.22
450.22
3
382.51
−397.23
4
358.48
786.6
5
368.18
−328.61
6
401.58
346.62
Image
Infinity
0
TABLE C2
i
K
ai
bi
ci
di
ei
1
−1.0
1.27808e−09
−7.70834e−15
1.08806e−19
1.44611e−24
−1.32003e−28
Stop
−1.0
1.28858e−10
−3.04390e−15
−1.03997e−19
7.79798e−25
0
3
−1.0
4.99689e−09
−7.16941e−14
2.40645e−17
−2.97337e−21
1.48591e−25
4
−1.0
−2.83190e−08
6.48095e−13
−6.87654e−18
2.16269e−23
8.53426e−29
5
−1.0
1.56374e−08
4.00468e−13
−1.32774e−18
3.49147e−22
−2.61910e−25
6
−1.0
2.13882e−09
7.73607e−15
3.27542e−20
3.54263e−25
−1.24655e−30

245 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/517,578Filed 8 Sep 2006
Priority: 9 Sep 2005
Published: 19 Jul 2007
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G02B 13/143
For use with infrared or ultraviolet radiation: for use with ultraviolet radiation
G02B 17/0663
Using more than three curved mirrors: off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry,…
G02B 27/0012
Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00: optical design, e.g. procedures, algorithms,…
G02B
Optical elements, systems or apparatus