JPH0442208A - Telecentric projection lens - Google Patents

Abstract

PURPOSE:To easily correct magnification change corresponding to the magnification change due to the error of lens working by nearly conforming the rear side focal point of a front side lens system to the front side focal point of a rear side lens system at a position in the neighborhood of a fourth lens system. CONSTITUTION:The front side lens system LF consisting of first to third lens groups 10-30 arranged sequentially at an image side from an object side, the fourth lens system 40 arranged at the image side of the front side lens group LF and capable of moving in an optical axis direction, and the rear side lens system LR consisting of fifth to seventh lens groups 50-70 arranged sequentially at the image side of the fourth lens system 40 are provided. The rear side focal point of the front side lens system LF is nearly conformed to the front side focal point of the rear side lens system LR at the position in the neighborhood of the fourth lens system 40. Thereby, it is possible to easily correct the magnification change due to the error of the lens working through it is symmetric type telecentric projection lens capable of easily correcting a various kinds of aberration including distortion aberration.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a telecentric projection lens suitable for use in the process of printing a fine pattern onto an exposure surface, particularly a projection lens whose aberrations are well corrected for two wavelengths. Regarding.

(Prior art and its problems) Examples of this type of lens include a projection lens for a stepper. Here, a stepper is a device that prints a fine pattern formed on a photomask onto a substrate coated with photoresist, and this stepper uses bright lines (g-line, h-line, i-line) of a mercury lamp. It is used as a light source. This is due to the fact that the photoresist's sensitive wavelength band is in the ultraviolet region. Furthermore, when printing fine patterns on photoresist, a stepper is required to have high resolution. Therefore, projection lenses for steppers are usually corrected for aberrations only for a single wavelength (eg, g-line).

However, from the viewpoint of shortening the exposure time and increasing work efficiency, it is sometimes preferable to increase the number of wavelengths used in printing. In other words, for example, it is more efficient to perform baking with G and H lines than to perform baking with only G lines.Moreover, it is more efficient to perform baking with G and H lines. Also from the viewpoint of making the degree uniform, it is desirable to use light of multiple wavelengths, as is well known in the art.

In addition, the projection lens must be designed to be telecentric on the image side so that the dimensions of the image remain approximately constant even if the distance between the projection lens and the substrate coated with photoresist is slightly shifted. There are many. However, the object side is usually not telecentric. This is because when both the object side and image side are telecentric, the imaging magnification cannot be changed even if the object distance and image distance are changed, and the imaging magnification depends on the lens configuration of the projection lens. It will be determined by. Therefore, if an error occurs in lens processing, the magnification of the projection lens will differ from the designed value. Further, for such lenses, no suitable method has been proposed for magnification correction, and it is difficult to correct magnification changes. In view of these circumstances, conventional projection lenses are telecentric only on the image side.

However, if only the image side is made telecentric as described above, it becomes impossible to design a projection lens while maintaining the symmetry of the lens. This is a disadvantageous condition in correcting various aberrations including distortion. In other words, it is relatively easy to correct the various aberrations of a symmetrical lens, but it is more difficult to correct aberrations for an asymmetrical lens than for a symmetrical lens.

(Purpose of the Invention) The present invention was made to solve the above problems, and although it is a symmetrical telecentric projection lens that can easily correct various aberrations including distortion, it does not require lens processing. It is an object of the present invention to provide a projection lens that can easily correct magnification changes caused by errors.

(Means for Achieving the Object) The present invention provides a projection lens having seven groups arranged completely symmetrically. or a front lens system consisting of a third lens group; and a front lens system disposed on the image side of the front lens system,
a fourth lens system movable in the optical axis direction; and a rear lens system consisting of fifth to seventh lens groups sequentially arranged on the image side of the fourth lens system, and further behind the front lens system. The side focal point and the front focal point of the rear lens system are made to substantially coincide at a position near the fourth lens system.

In order to better achieve the above object, the invention of claim 2 is such that each of the first and seventh lens groups is composed of a single lens, and each of the 2.3.56 lens groups is composed of two single lenses. The fourth lens group is made up of three 11 lenses stuck together, and the radius of curvature of the first (1-1 to 20) lens surface counting from the object side is r3, 1st (i-1) counting from the object side
The distance between lens surfaces on the optical axis between the lens surface of ~19) and the (i+1)th lens surface is d9, and the distance between the lens surfaces of the jth lens (j-1 to 13) counting from the object side is for the g-line and h-line Letting the refractive index be n, , n, respectively, gJ
hJ, these are (blank below) r l-255-7[15 rz--290,468 rs =84.119 r 4 =-235,8B2 r 5-826-718 r e-158,435 r7= =129.040 rg "" 42.183 rs-81,152 r, o=-69,754 r,, = 69.754 r, 2=-81,+52 r, 3--42.183 r, 4- -29.040 rl5 - 153.435 r, 6 = -826,718 r, 7 = 285.862 r, 8 = -84,119 r, 9 = 290.468 r 2o = -255,785 d, = 8 .829 62=44.736 d3=10.924 d4= 8.946 d5=29.767 d6= 2.712 67-1.288 d8-35.536 d9-9.000 d, o=18.000 dl , = 9.000 d, 2 = 35.536 d, 3 = 7.2 [18 d, 4 = 2.712 d ■5-29.787 6te = 3.946 d, 7 = 10.924 d, 8 -44.736 d19= 8.829 ngt ”' I・75176 ng2″″1・70971 n g3−1・135742 0g4=1.63107 n g5=1−66381 nge =t, es3te ng7=1・63107 ng8” '1・63316 n g9″″1・8L181 ngto -t, eatoy ng11=1. [15742 0g12 = 1・70971 ngta = 1.75176 n,, ■ = 1.75827 nh2 = 1.7 + 5 [15 nh3 = 1.68433 nh4"" 1.68776 nh5 = 1.86951 nh6 = 1.63778 nh7- 1.63776 nh8= 1.63778 nh9-1. ．． 136951 nhio = 1.68778 nhl, ``1.88433 nhl2-1.71565 nhl3-1.75827''.

Further, in order to better achieve the above object, the invention of claim 3 has the structure of each lens group similar to that of the invention of claim 2, and the i-th lens group counting from the object side (i=1 to 2).
0) is the radius of curvature of the lens surface ri, counting from the object side is i
The distance between the lens surfaces on the optical axis between the (i-1 to 19)th lens surface and the (i+1)th lens surface is dl, and g of the jth lens (j-1 to 13) counting from the object side is When the refractive indices for the line and h line are n, , n, respectively, these are: --272-084 rs-288,262 re-157,49:1 r7=33.615 re, =42.769 rta =84.133 r, o=-65,6B1 r u= 65. fi61 r, 2=-84,133 'IS agony-42,7 [19 r, 4--83.615 r15= 157.493 '16 child-288.262 r, 7= 272.084 r, 8=- 81,491 r, 9= 288.117 r,, o=-294,98O d, = 8.20B d2=84.302 d3-9.422 64= 4.520 65=31.512 1= 1. ．． 300 d7 = 2.250 d8 = 34.956 d9 = 9.500 d, o = 19.000 611 = 9.500 6.2 = 44.956 d, 3 = 2.250 d14 = IJOO d 15-31. 512 d, 6=4.52n d, 7=9.422 d, 8=64.302 d, 9=8.206 n gl =1-75176 n g2-1・70971 0g3-1・85742 0g4=1・631O7 ng5=t, eeagt nge =1・65811 n g7-1・68107 1g8=1・65[111 ng9-t, eesst ``gto=1.88107 'g11''''1・65742 0g12-1.70971 0g18'''' 1・7517B nhl= 1.75827 n,, 2-1.715[!5 nh3-1.8B438 ``h4 = 1.113778 nh5= 1.66951 'he = 1.66+04 nh7= 1.88778 n,, 8 = 1.8B+04 nh9-1.66951 nhlo=1.63776 nh, -1,68433 nh, 2=1.71565 nh13=1.75827.

(Operation) According to this invention, the projection lens is completely symmetrical. Therefore, distortion, single lateral chromatic aberration, and meridional coma become zero, and other aberrations can also be reduced. Moreover, since the fourth lens group is movable in the optical axis direction, the fourth lens group is moved in the optical axis direction in response to changes in magnification due to errors in lens processing.
The magnification change is corrected.

(Embodiment) FIG. 1 is a diagram showing a first embodiment of a telecentric projection lens according to the present invention. This projection lens is composed of 13 lenses in 7 groups arranged completely symmetrically. In this projection lens, as shown in FIG.
1st to 13th from the left side of the figure) to the image side (right side of the figure 1)
Lens 11゜21.22, 31, 32, 41, 42, 4
3, 51.52, 61.62.71 are arranged in this order.

As shown in the figure, the first rung group 1 is
0 is configured. In addition, the 2nd degree third lens 21.2
2 are bonded together to form a second lens group 20. Furthermore, the fourth. Fifth lens 31. ．． 32 are bonded together to form the third lens group 30. A front lens system LP is formed from the first to third lens groups 10, 20, and 30 configured in this manner.

Further, the fourth lens 1140 is configured by bonding the sixth to eighth lenses 41, 42, and 43 together. In addition,
This fourth lens group 40 is configured to be movable in the optical axis Z direction.

To Sarah, No. 9. The fifth lens group 50 is configured by bonding the tenth lenses 51 and 52 together.

Also, No. 11. Twelfth lens 61. ．． 62 are bonded together to form a sixth lens group 60. Furthermore, the first
A seventh lens group 70 is composed of three lenses 71. The fifth to seventh lens groups 50 configured in this way
, 60.70, a rear lens system LR is formed.

Note that this projection lens is the front lens system L■.

The rear focal point and the front focal point of the rear lens system LR substantially coincide with each other near the fourth lens system 40, and are telecentric on the object side and image side.

Table 1 shows lens data of the projection lens configured as described above.

(Margins below)] 5 r, = 255.765 r2-290-488 r3-84.119 r4″″-235・862 r5= 326.7+8 re, −-153,435 r-t =29.040 rg” " 42.183 rq = 81.152 r, o = -69,754 r, 1 = 69.754 r, 2 = -8+, 152 r13 = -42,183 r ■4 = -29,040 '15 = 153 -435 r, 6 = -328,718 r, 7 = 235.8B2 r, 8 = -84,119 r, 9 = 290.468 r 2o - 255,785 d, = 8.829 d2 = 44.736 63 = I0.924 d4 = 3.946 d5 = 29.767 d6 = 2.712 d7 = 7.268 d8 = 35.536 69 = 9.000 d, o = 18.0OO d,, = 9.000 6 .2 = 35.538 d, 3 = 7.268 6.4-2.712 6.5 = 29.787 d, 6-3.946 d17 = 10.924 d 18 = 44.73 [i d, 9 = 8.829 Table ng+-L7517fj n g2 =1-70971 n g3-165742 ng4= 1.63107 n g5-1・6B:181 n g6″″1・83316 n g7-163' 07 n gs-1-63318 ngq =1.66381 ng, o-1,63107 ngll=1.85742 ng,, -1,70971 ng, 3=1.75176 n11. = 1.75827 nh,, = 1.715B5 n, 8 = 1. ．． 86483 nh4=1. B5778 n 1,5 =-], B66951 nhe -1,68778 nh7-1.83776 nh8 = 1.88778 n, 19 = 1.8695I n,, ■ o = 1.63776 n, 4. l=1.864.33 nh,2-i,,71565 nh,3=1.75827 In the same table, r is the i-th (i=1
~20) The radius of curvature of the lens surface is d.

is the distance between the lens surfaces on the optical axis Z between the first (i-1 to 1) lens surface and the (i+1) [1] lens surface counting from the object side, n,, n is the distance from the object side A few gj
bj In addition, the refractive index of the fifth lens (j-1 to j-13) with respect to the g-line and the h-line is shown, respectively.

Note that the numerical aperture (NA) of the telecentric projection lens configured as described above is 0.053, the imaging magnification is (-1,0) times, and the screen size is 71.0.

FIGS. 2 and 3 are diagrams showing the spherical aberration and astigmatism, respectively, of the projection lens configured as described above. In FIG. 2 (and FIG. 7, which will be described later), solid lines g and broken lines indicate spherical aberrations for the g-line and h-line, respectively.

In addition, in FIG. 3 (and FIG. 8, which will be explained later),
The solid lines g(S) and h(S) indicate the sagittal image planes for the g-line and h-line, respectively, and the broken lines g(M) and h(M
) indicate the meridio] 8 null image plane for the g-line and h-line, respectively.

Figures 4 and 5 are meridional image planes, respectively.

FIG. 3 is a diagram showing comatic aberration on a sagittal image plane. In both figures, the solid line g and the broken line indicate the results for the g line and h line, respectively.

As can be seen from FIGS. 2 to 5, according to this embodiment, good resolution can be obtained over the entire screen at two wavelengths, g-line and h-line. Furthermore, since the fourth lens group 40 is configured to be movable in the optical axis Z direction, even if the magnification changes due to errors in lens processing, the fourth lens group 40 can be moved in the optical axis direction. Changes in magnification can be easily corrected by movement. Moreover, since the projection lens is a completely symmetrical system, distortion aberration, lateral chromatic aberration, and meridional coma can be reduced to zero.
Furthermore, other aberrations can be corrected relatively easily.

Next, other embodiments will be described.

As another example, as shown in FIG.
Distance between lens surfaces d1, refractive index nll+1
1
There are cases where gJn hj satisfies the following values.

(Left below) r r =294-96O r 2--288.117 ra ”” 81.491 r 4-2'12.0g4 rr, =288.282 re-157,498 r7=83. fi15 rs "" 42.769 rta-84,133 r, low -65,681 r I, = 65.661 r, 2--84. B13 r13= -42,769 r14= -33, [115 r, 5-157.493 r I6--288.282 r17-272.084 r, 8--81.491 r +9 =288-117 r,, o=-294,960 dl-8゜206 d2-84.302 d3= 9.422 d4-4.520 65=81.512 1= 1.300 d7= 2.250 d8-34.958 d9= 9. 500 d, Low 19.000 d, -9,500 d, -84,958 d, 3-2.250 d14= 1.300 d15 31.512 d, 8-4°520 d, 7= 9.422 d, 8=64.302 d, 9-8.206 Table n gl=1-75176 n g2-1 ・7097'0g3''''l ・65742 ng4=1・[13107 n g5'''l ・66381 n ge-1-65611 ngy ”” 1-83107 n gg ′””1-65811 ng9 snow t, east nglO-1, 83107 ng, ■-1.li5742 ng, 2””1.70971 ng13-1. 75178 nh1= 1.75827 nh2-1.71565 nh3-1.884Ll nh4= 1.B5778 nh5-1.136951 nh6-1.66104 n, 7" 1.68778 nh8-1. [1B104 nh9-1. ee95t nh, o=1. L1776 nh, -1,13fi438 nhI2-1.71585 n,13 1.75827 The numerical aperture (NA) of the telecentric projection lens configured as above is 0.053, and the imaging magnification is ( -1,0) times, and the screen size is 71.0.

FIGS. 7 and 8 are diagrams showing spherical aberration and astigmatism, respectively, of the projection lens shown in FIG. 6. Further, FIGS. 9 and 10 are diagrams showing coma aberration of the meridional image plane and the sagittal image plane, respectively.

As shown in FIGS. 7 to 10, this embodiment also provides good resolution over the entire screen at two wavelengths, G-line and H-line. Furthermore, since this embodiment employs the same configuration as the first embodiment described above, the first
Needless to say, the same effects as in the embodiment can be achieved.

In the above embodiment, two wavelengths, g-line and h-line, were explained, but the invention is not limited to this, and any two wavelengths can be obtained by designing a projection lens according to the present invention.
Effects similar to those described above can be obtained regarding wavelength.

(Effects of the Invention) As described above, according to the present invention, since the projection lens is completely symmetrical, distortion aberration, single lateral chromatic aberration, and meridional coma aberration can be reduced to zero, and other aberrations can also be reduced. I can do it.

Furthermore, since the fourth lens group is movable in the optical axis direction, it is possible to correct the change in magnification by moving the fourth lens group in the optical axis direction in accordance with a change in magnification due to an error in lens processing. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the telecentric projection lens according to the present invention, and FIGS. 2 and 3 are diagrams respectively showing spherical aberration and astigmatism of the projection lens. 5 and 5 are diagrams showing the coma aberration of the meridional image plane and the zagittal image plane, respectively, FIG. 6 is a diagram showing the second embodiment of the telecentric projection lens according to the present invention, and FIG. 7 and FIG. Figure 8 shows the spherical aberration and astigmatism of the projection lens, respectively, and Figures 9 and 10 respectively show the meridional image plane and the astigmatism.
FIG. 3 is a diagram showing comatic aberration on a sagittal image plane. ]0... 1st lens group, 20... 2nd lens group, 30
...Third lens group, 40...Fourth lens group, 50.
・・5th lens group, 60・・6th lens group, 70・
・・7th lens group, L, ・・front lens system, LR・
...Back lens system, Z ...Kosuke agent Patent attorney Yoshi111.1 Shigeaki

Claims (3)

[Claims] (1) A projection lens with seven groups arranged in perfect symmetry, including a front lens system consisting of first to third lens groups arranged sequentially from the object side to the image side, and the image side of the front lens system. a fourth lens system that is disposed in the front lens system and movable in the optical axis direction; and a rear lens system that includes fifth to seventh lens groups that are sequentially disposed on the image side of the fourth lens system, and the front lens A telecentric projection lens characterized in that a rear focal point of the system and a front focal point of the rear lens system substantially coincide at a position near the fourth lens system. (2) The first and seventh lens groups each consist of a single lens, and the second, third, fifth, and sixth lens groups each consist of two lenses.
The fourth lens group is made by bonding three single lenses together, and the i-th (i=1 to 20) lens surface counting from the object side is the fourth lens group. The radius of curvature of is r_i, i-th (counting from the object side)
The inter-lens distance on the optical axis between the lens surface of i=1 to 19) and the (i+1)th lens surface is d_i, and the g-line of the jth lens (j=1 to 13) counting from the object side, When the refractive index for the h-line is n_g_j and n_h_j, these are r_1=255.765d_1=8.82
9n_g_1=1.75176n_h_1=1.758
27r_2=-290.468d_2=44.736r
_3=84.119d_3=10.924n_g_2=
1.70971n_h_2=1.71565r_4=-
235.862d_4=3.946n_g_3=1.6
5742n_h_3=1.66433r_5=326.
718d_5=29.767r_6=-153.435
d_6=2.712n_g_4=1.63107n_h
_4=1.63776r_7=29.040d_7=7
．． 268n_g_5=1.66381n_h_5=1.
66951r_8=42.183d_8=35.536
r_9=81.152d_9=9.000n_g_6=
1.63316n_h_6=1.63778r_10=
-69.754d_1_0=18.000n_g_7=
1.63107n_h_7=1.63776r_1_1
=69.754d_1_1=9.000n_g_8=1
．． 63316n_h_8=1.63778r_1_2=
-81.152d_1_2=35.536r_1_3=
−42.183d_1_3=7.268n_g_9=1
．． 66381n_h_8=1.66951r_1_4=
-29.040d_1_4=2.712n_g_1_0
=1.63107n_h_1_0=1.63776r_
1_5=153.435d_1_5=29.767r_
1_8=-326.718d_1_6=3.946n_
g_1_1=1.65742n_h_1_1=1.66
433r_1_7=235.862d_1_7=10.
924n_g_1_2=1.70971n_h_1_2
=1.71565r_1_8=-84.119d_1_
8=44.736r_1_9=290.468d_1_
9=8.829n_g_1_3=1.75176n_h
_1_3=1.75827r_2_0=-255.76
5. The telecentric projection lens according to claim 1, which satisfies the following. (3) The first and seventh lens groups each consist of a single lens, and the second, third, fifth, and sixth lens groups each consist of two lenses.
The fourth lens group is made by bonding three single lenses together, and the i-th (i=1 to 20) lens surface counting from the object side is the fourth lens group. The radius of curvature of is r_i, i-th (counting from the object side)
The inter-lens distance on the optical axis between the lens surface of i=1 to 19) and the (i+1)th lens surface is d_i, and the g-line of the jth lens (j=1 to 13) counting from the object side, When the refractive index for the parallel line is n_g_j and n_h_j, these are r_1=294.960d_1=8.20
6n_g_1=1.75176n_h_1=1.758
27r_2=-288.117d_2=64.302r
_3=81.491d_3=9.422n_g_2=1
．． 70971n_h_2=1.71565r_4=-2
72.084d_4=4.520n_g_3=1.65
742n_h_3=1.66433r_5=288.2
62d_5=31.512r_6=-157.493d
_6=1.300n_g_4=1.63107n_h_
4=1.63776r_7=33.615d_7=2.
250n_g_5=1.66381n_h_5=1.6
6951r_8=42.769d_8=34.956r
_9=84.133d_9=9.500n_g_6=1
．． 65611n_h_6=1.66104r_1_0=
-65.661d_1_0=19.000n_g_7=
1.63107n_h_7=1.63776r_1_1
=65.661d_1_1=9.500n_g_8=1
．． 65611n_h_8=1.66104r_1_2=
-84.133d_1_2=34.956r_1_3=
-42.769d_1_3=2.250n_g_9=1
．． 66381n_h_8=1.66951r_1_4=
−33.615d_1_4=1.300n_g_1_0
=1.63107n_h_1_0=1.63776r_
1_5=157.493d_1_5=31.512r_
1_6=-288.262d_1_6=4.520n_
g_1_1=1.65742n_h_1_1=1.66
433r_1_7=272.084d_1_7=9.4
22n_g_1_2=1.70971n_h_1_2=
1.71565r_1_8=-81.491d_1_8
=64.302r_1_9=288.117d_1_9
=8.206n_g_1_3=1.75176n_h_
The telecentric projection lens according to claim 1, which satisfies the following: 1_3=1.75827r_2_0=-294.960.