JP2000010005A - Catadioptric projection exposing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catadioptric projection exposing device capable of easily adjusting plural optical axes and moreover, hardly causing the deterioration of image-formation performance even after assembling. SOLUTION: In this catadioptric projection exposing device in which an image on a 1st surface is formed on a 2nd surface by an optical member including a dioptric member, a curved surface mirror and an optical path deflecting member, the exposing device has two or more optical path deflecting members and N (N>=3) pieces of optical axes z1, z2 and z3 and has M (M>=N) sets of barrels 1, 2 and 3 as a whole by holding the optical member arranged on the individual optical axis by one or plural sets of the barrels. Any one of the barrel 2 holds two optical path deflecting members and at least either of the other barrels 1 or 3 holds only the dioptric member or only the dioptric member and the curved surface mirror.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system of a projection exposure apparatus used for manufacturing, for example, a semiconductor device or a liquid crystal exposure apparatus in a photolithography process.
In particular, by using a reflection system as one element of the optical system,
The present invention relates to a holding structure of a catadioptric optical system having a resolution of a quarter micron.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device or the like, an image of a pattern on a photomask or reticle (hereinafter, collectively referred to as a reticle) is formed by a photoresist or the like via a projection optical system. 2. Description of the Related Art A projection exposure apparatus that exposes a wafer or a glass plate or the like (hereinafter, collectively referred to as a wafer) on which a coating is applied is used.
As the degree of integration of semiconductor elements and the like increases, the resolution required for a projection optical system used in a projection exposure apparatus has been increasing. In order to satisfy this requirement, it has been necessary to shorten the wavelength of the illumination light and increase the numerical aperture (NA) of the projection optical system.

However, when the wavelength of the illumination light is shortened, the types of glass materials that can withstand practical use due to light absorption are limited, and when the wavelength is 300 nm or less, only synthetic quartz and fluorite are currently practically usable. . Since the Abbe numbers of the two are not sufficiently separated to correct the chromatic aberration, it is difficult to correct the chromatic aberration. Further, since the required optical performance is extremely high, it is necessary to make each aberration almost aberration-free. In order to achieve this with a refractive optical system composed of only a lens group, a large number of lenses are required, and a reduction in transmittance and an increase in costs for manufacturing the optical system cannot be avoided.

On the other hand, a reflecting optical system using the power of a concave mirror or the like has no chromatic aberration and shows a contribution to the Petzval sum opposite to that of a lens. Therefore, a so-called reflecting optical system combining a reflecting optical system and a refracting optical system is used. According to the refracting optical system, various aberrations including chromatic aberration can be made almost aberration-free without increasing the number of lenses. Various techniques have been proposed in which a projection optical system is constituted by such a catadioptric optical system. As a representative of them,
JP-A-63-163319, JP-B-7-1115
No. 12, JP-B-5-25170, USP-
No. 4,779,966 are disclosed.

[0005]

However, at present, the optimum block configuration and assembly adjustment of the catadioptric optical system are not well understood. That is, in general, in a catadioptric optical system, it is necessary to use an optical path deflecting member in order to separate the optical path on the outward path toward the concave mirror and the optical path on the return path from the concave mirror, and as a result, there are a plurality of optical axes. . Therefore, when assembling the catadioptric optical system, there is a problem that an error is more likely to occur in the mutual adjustment between the plurality of optical axes than in the refractive optical system. Also, once assembled, the stability is poor due to the complicated configuration,
There is a problem that the positional relationship between the optical axes is gradually shifted, and the image is likely to deteriorate. For this reason, although the catadioptric optical system is superior to the dioptric optical system in design, it has actually caused the practical use of the catadioptric optical system not to progress. In view of the above, an object of the present invention is to provide a catadioptric projection exposure apparatus which can easily adjust a plurality of optical axes and hardly cause deterioration of imaging performance even after assembly.

[0006]

In order to solve the above problems, in the present invention, optical members having the same optical axis are collectively held by a barrel. That is, the present invention relates to a catadioptric projection exposure apparatus that forms an image on a first surface on a second surface by using an optical member including a refractive optical member, a curved mirror, and an optical path deflecting member. The optical path deflecting member and N (N ≧ 3) optical axes are provided, and one or a plurality of the optical members arranged on each optical axis are held by a barrel, whereby M
(M ≧ N) barrels, at least one of the M barrels holds two of the optical path deflecting members and before and after being bent by the two optical path deflecting members. Holding both optical path deflecting members so that the optical axes are parallel to each other, at least one of the other barrels of the M barrels holds only the refractive optical member, or the refractive optical member and A catadioptric projection exposure apparatus characterized by holding only the curved mirror.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an optical path diagram of a projection optical system used in a catadioptric projection exposure apparatus according to one embodiment of the present invention. The projection optical system forms an intermediate image S of the pattern on the reticle R by the first imaging optical system A, and re-images the intermediate image S by the second imaging optical system B on the photosensitive surface of the wafer W. To form. The optical axis (first optical axis z ₁ ) of the first imaging optical system A is arranged in the vertical Z direction. Also,
The first imaging optical system A consists front group A ₁ and the rear group A ₂ Prefecture, after group A ₂ is disposed concave mirror M _C, and therefore the rear group A
₂ is a reciprocating optical system. And the first imaging optical system A
The intermediate image S of the pattern by is formed in the middle of a front group A ₁ and the rear group A _2. A first plane mirror M ₁ is arranged near the position of the intermediate image S, and the first optical axis z ₁ of the first imaging optical system A is bent by 90 ° by the plane mirror M ₁ , so that the left and right Y directions are changed. the second has a optical axis z ₂ extending. A second plane mirror M ₂ is disposed on the second optical axis z _2, and the second plane mirror M ₂
As a result, the second optical axis z ₂ is further bent by 90 ° to form a third optical axis z ₃ extending in the vertical Z direction. Therefore, the two plane mirrors M ₁ and M ₂ are orthogonal to each other and both form an angle of 45 ° with the second optical axis z ₂ . A second imaging optical system B is arranged on the third optical axis z ₃ , and an aperture stop AS is arranged inside the second imaging optical system B.

The projection optical system includes a first imaging optical system rear group A
_{Since 2} is a reciprocating optical system, the positions of the reticle pattern surface and the wafer photosensitive surface on the optical axes z ₁ and z ₃ are not used areas. That illumination area of the illumination optical system (not shown) for illuminating the reticle pattern has a first optical axis z ₁ a detached front and rear X-direction long slit-like, as a result, also the exposure region of the projection optical system second 3 has an optical axis z ₃ to the removed longitudinal X direction long slit shape. The whole area of the reticle pattern is transferred to the photosensitive surface of the wafer by scanning the reticle R and the wafer W synchronously in the left and right Y directions.

The main specifications of the projection optical system of this embodiment are as follows. A. : 0.75 Magnification: 0.25 times Used wavelength: 193.3 nm (ArF excimer laser). The exposure area may be, for example, a rectangular area measuring 25 mm × 6 mm in length in the front-back X direction × length in the left-right Y direction. Table 1 below lists specifications of the optical members of the projection optical system. In [optical member specifications] in Table 1, the first column No is the number of each optical surface from the reticle R side, the second column r is the radius of curvature of each optical surface, and the third column d is the following from each optical surface. The distance on the optical axis to the optical surface, the fourth column R _eff is the effective radius of each optical surface,
The fifth column shows the glass material from each optical surface to the next optical surface (blank is air), and the sixth column shows the symbol of each optical member or the symbol of the group to which the optical member belongs. The radius of curvature r and the distance d on the optical axis are assumed to be positive in the traveling direction of light, but the sign is reversed each time the light is reflected once. The refractive indexes of quartz and fluorite at the wavelengths used are as follows. Quartz: 1.560326 Fluorite: 1.501455

The 39th and 52nd surfaces use aspherical surfaces, and the second column r for the aspherical surface is the radius of curvature of the apex. The shape of the aspheric surface is y: height from the optical axis z: distance in the optical axis direction from the tangent plane to the aspherical surface r: vertex radius of curvature κ: conical coefficient A to F: aspherical surface coefficient The values of the aspherical coefficients A to F are shown. Regarding the conical coefficient, κ = 0 for each aspheric surface.

[0011]

[Table 1] [Optical member specifications] Nord R _eff 0 ∞ 50.0980 R 1 ∞ 30.8769 77.96 Quartz A ₁ 2 1358.1393 25.6596 82.00 3 -173.9366 29.5956 82.54 Quartz A ₁ 4 -262.5027 3.9549 93.62 5 -243.7585 32.1846 94.30 Quartz A ₁ 6 -198.6141 79.2508 102.23 7 705.6754 29.6916 128.29 quartz _{A 2 8 -853.6854 7.1157 128.85 9 243.8837} 35.0000 130.00 quartz _{A 2 10 393.9524 334.9670 126.27 11 -228.4608} 20.5261 87.25 quartz _{A 2 12 324.6767 7.3561 90.62 13 359.7325} 40.5663 92.51 fluorite A ₂ 14 -554.2952 58.0131 94.34 15 588.9791 33.3872 97.95 quartz _{A 2 16 3573.1266 113.1955 97.48 17 -249.4612} 25.0000 111.74 quartz _{A 2 18 -1326.9703 25.8354 126.13 19 -367.4917} -25.8354 129.94 A 2 M C 20 -1326.9703 -25.0000 127.54 quartz A ₂ 21 -249.4612 -113.1955 117.01 22 3573.1266 -33.3872 112.48 Quartz A ₂ 23 588.9791 -58.0131 111.89 24 -554.2952 -40.5663 100.25 Fluorite A ₂ 25 359.7325 -7.3561 97.36 26 324.6767 -20.5261 94.44 Quartz A ₂ 27 -228.4608 -334.9670 87.51 -35.0000 93.84 Quartz _{A 2 29 243.8837 -7.1157 96.50 30 -853.6854} -29.6916 93.81 Quartz _{A 2 31 705.6754 1.6203 92.09 32 ∞} 530.0000 M 1 33 ∞ -100.0000 M 2 34 -473.4614 -50.8662 130.00 quartz B 35 1218.5628 -18.9785 128.42 36 357.1688 -31.0635 128.11 Quartz B 37 818.7536 -209.4034 129.93 38 -571.9096 -31.2079 123.89 Quartz B 39 -295.8211 -4.7127 119.48 40 -291.2028 -53.9868 119.84 Fluorite B 41 858.6769 -19.1416 119.00 42--24.0577 115.27 113 -25. B 44 6715.0030 -22.3498 117.19 45 -314.9647 -45.0000 124.79 Quartz B 46 -5036.3103 -16.5385 123.55 47 -265.1907 -45.0000 120.07 Quartz B 48 9375.9412 -1.1109 116.54 49 -177.9561 -50.1531 103.37 Quartz B 50 -18823.9455 -4.9217 9491 25.0000 93.03 Quartz B 52 -247.3912 -1.0000 74.54 53 -210.5206 -24.3364 73.99 Quartz B 54 -35247.2125 -1.0621 69.21 55 -293.7588 -65.0000 63.01 Quartz B 56 56893.1197 -12.3837 31.15 57 Ｗ W [Aspherical data] No = 39 A = -1.3500 × 10 ^-8 B = -1.2494 × 10 ^-13 C = -1.3519 × 10 ^-18 D = -9.1832 × 10 ^-23 E = 3.6355 × 10 ^-27 F = -1.6744 × 10 ^-31 No = 52 A = -4.8402 × 10 ^-8 B = -1.1379 × 10 ^-12 C = -6.8704 × 10 ^-17 D = -2.8172 × 10 ^-21 E = 0 F = 0

Next, the support structure of the projection optical system will be described. 2 (a), 2 (b), 3 (a), 3 (b)
Respectively shows a plan view, a central vertical sectional view, a left side view, and a right side view of the projection optical system. As shown in the figure, the first imaging optical system A of the projection optical system has a first cylindrical optical system.
The first plane mirror M ₁ and the second plane mirror M ₂ are fixed in a barrel 1, and are fixed in a second barrel formed in a truncated pyramid shape, and the second imaging optical system B is a third barrel. 3 is fixed. FIGS. 4, 5 and 6 show a first barrel 1, a second barrel 2 and a third barrel 3, respectively.

On the other hand, as a support structure for the projection optical system, there is provided a lower pedestal 5 formed in a flat plate shape.
Is provided with an opening through which the first barrel 1 and the third barrel 3 pass. Of these, four main columns 6a to 6d are erected around the opening for the first barrel 1, and the upper pedestal 7 is fixed to the upper surfaces of the main columns 6a to 6d. The upper base 7 has a U-shaped opening for supporting the first barrel 1. On the upper part of the first barrel 1, there is provided a flange 1a which protrudes laterally.
The first barrel 1 is supported by being placed on the upper surface around the U-shaped opening of the upper base 7. Similarly, a flange 3a that protrudes laterally is provided at the lower part of the third barrel 3, and the lower surface of the flange 3a is placed on the upper surface around the opening for the third barrel of the lower frame, so that Three barrels 3 are supported.

On the other hand, a pair of auxiliary columns 8a and 8b formed in an inverted L-shape are fixed between the first barrel opening and the third barrel opening of the lower base 5, and the second barrel. 2 is supported by the auxiliary columns 8a and 8b. 7 and 8 show a lower support, a main support and an upper support, and FIG. 9 shows an auxiliary support. As described above, the gantry of the exposure apparatus of this embodiment includes the lower gantry 5, the main columns 6a to 6d,
It consists of an upper base 7 and auxiliary columns 8a, 8b, and the barrels 1, 2, 3 are supported by the base independently of each other.

Next, the first barrel 1 is supported by the lower surface of a flange 1a provided on the first barrel 1. The position of the lower surface of the flange 1a is defined by the distance from the pattern surface of the reticle R to the intermediate image S. The interval is at a position that is internally divided at a ratio of 1: (− β _A ). Here, β _A is the imaging magnification of the first imaging optical system A.
The imaging magnification β _A of the first imaging optical system of this embodiment is approximately β _A =
−1.25, and therefore, the position of the lower surface of the flange 1a of the first barrel 1 is substantially at the midpoint of the distance from the reticle R to the intermediate image S, ie, 106 m below the lower surface of the reticle R.
m (horizontal plane passing through P _A in FIG. 2B). Similarly, the third barrel 3 is supported by the lower surface of the flange 3a provided on the third barrel 3, and the position of the lower surface of the flange 3a is
The distance from the intermediate image S to the photosensitive surface of the wafer W is 1: (−
β _B ). Where β _B is the second
This is the imaging magnification of the imaging optical system B. The imaging magnification β _B of the second imaging optical system of this embodiment is approximately β _B = −0.20, and therefore the position of the lower surface of the flange 3 a of the third barrel 3 is from the intermediate image S to the wafer W. the distance of 1: point which internally divides at 0.20 ratio of, i.e. at a distance 232mm measured along the optical axis upward from the wafer W (horizontal plane passing through the P _B in Figure 2 (b)).

The operation of this configuration will be briefly described with reference to FIG. Assuming that the object height for an arbitrary imaging optical system is h ₀ , the image height is y ₀ , and the lateral magnification is β, β = y ₀ / h ₀ . However, the heights of the object and the image are measured in the same direction. Therefore, in the example shown in FIG. 10, h ₀ <0, y ₀ > 0
It is. Further, since the specific configuration and arrangement position of the imaging optical system do not matter, the optical axis z _{0 of the} imaging optical system is shown in FIG.
Only shown. Here, assuming that the imaging optical system is rotated counterclockwise by a small angle θ about the point P on the optical axis z ₀ , the optical axis after rotation is z ₁ . 1 like a catadioptric system
Even when a light beam passes through two lenses twice, the distance on the optical axis measured from the object point to the image point is defined as positive, and the distance on the optical axis from the object point to the rotation center P is defined as a. , Rotation center P
When b the distance on the optical axis to the image point from the object height h ₁ and the image height y ₁ after rotation becomes _{h 1 = h 0 + aθ y} 1 = y 0 -bθ. Between the object height h ₁ and the image height y ₁ after rotation, if established relationship y ₁ / h ₁ = beta, does not shift the image point even after rotation of the image forming optical system. From the above equations, a: b = 1: (− β) is obtained. In other words, even if the imaging optical system rotates around a point that internally divides the object-image distance at a ratio of 1: (− β) (the outer division point when β is positive), the image point does not deviate. It can be seen that the image optical system is preferably supported at point P.

Next, the effects of this embodiment will be described below. The degrees of freedom of the position that the three-dimensional object can take are X, Y,
This is convenience 6 between the position in the Z direction and the angular position around the X, Y, and Z axes. The first barrel 1 and the third barrel 3 are both flange 1
Since each of the lower surfaces a and 3a is separately supported by the gantry, it is unlikely that any of the parallel movement in the vertical Z direction, the parallel movement in the horizontal X and Y directions, and the rotation around the vertical axis Z will occur. In particular, the vertical axis Z is the direction of the optical axes z ₁ and z ₃ , and both the first imaging optical system A and the second imaging optical system B are formed symmetrically around the optical axes z ₁ and z ₃ . Even if rotation about the vertical axis Z occurs, no aberration occurs.

As described above, the only movement that can occur in the first barrel 1 and the third barrel 3 is a rotation about the horizontal axes X and Y. However, the first barrel 1 is supported by a plane that internally divides the object-image distance of the first imaging optical system A held by the barrel 1 at a ratio of 1: (− β _A ), and the third barrel 3 Is the distance between object images of the second imaging optical system B held by the barrel 3 is 1:
Since the first barrel 1 or the third barrel 3 is rotated around the horizontal axes X and Y, the amount of image shift is small because the first barrel 1 or the third barrel 3 is supported on a plane internally divided at a ratio of (−β _B ). . Also, the first
Since an image shift caused by the barrel 1 and the third barrel 3 hardly occurs, when an image shift occurs, it is understood that the cause is any one of the wafer stage, the reticle stage, and the second barrel 2. That is, it is easy to specify the cause of the image shift.

Next, the second barrel 2 is unlikely to cause a parallel movement in the vertical Z direction and a parallel movement in the horizontal X and Y directions, but may rotate around the X, Y and Z axes. Occurs, image shift occurs. However, since the second barrel 2 is held directly from the gantry, even if the first barrel 1 or the third barrel 3 vibrates, the vibration is not transmitted and the second barrel 2 does not vibrate. Therefore, if the stability of the gantry is increased, the vibration of the second barrel 2 can be sufficiently prevented.

The configuration of this embodiment is also effective when assembling the projection optical system. As shown in FIG. 2, to assemble the projection optical system, first, each barrel is assembled. At this time, since each barrel has a single optical axis, it is easy to assemble.
Of these, the first barrel 1 and the third barrel 3 shown in FIGS. 4 and 6 may be sequentially stacked so that the optical axes z ₁ and z ₃ do not shift from the lower optical member. The second barrel 2 shown in FIG. 5 may be assembled so that the _two plane mirrors M ₁ and M ₂ are at right angles. Next, in order to assemble the entire projection optical system, first, the first barrel 1 and the third barrel 3 are connected as shown in FIG.
And into the stand shown in FIG. At this time, it may be difficult to completely match the positional relationship between the two with the design data.

The positional deviation between the first barrel 1 and the third barrel 3 includes a height deviation in the vertical Z direction, a left and right Y
It is considered that the distance between the optical axes in the directions is shifted. Of these, if there is a height shift between the first barrel 1 and the third barrel 3,
The total length on the optical axis from the reticle to the wafer deviates from the design data. In this case, when the second barrel 2 is fitted to the auxiliary column shown in FIG. 9, by adjusting the mounting height of the second barrel 2, the total length can be as designed. Also, a first barrel 1 and a third barrel 3
When there is a deviation in the distance between the optical axes, the position of the second barrel 2 is adjusted in the left and right Y direction,
The deviation of the distance between the optical axes can be absorbed. Thus, by adjusting the position between the barrels, the projection optical system can be easily assembled according to the design data.

[0022]

According to the present invention, it is possible to provide a catadioptric optical system which does not cause deterioration of an image and is easy to assemble and adjust.

[Brief description of the drawings]

FIG. 1 is an optical path diagram of a projection optical system used in a catadioptric projection exposure apparatus according to one embodiment of the present invention.

FIG. 2A is a plan view showing a projection optical system, and FIG.

3A and 3B are a left side view and a right side view showing a projection optical system.

4A is a plan view, FIG. 4B is a longitudinal sectional view, FIG. 4C is a left side view, and FIG. 4D is a right side view showing the first barrel.

5A is a plan view, FIG. 5B is a vertical sectional view, FIG. 5C is a left side view, and FIG. 5D is a right side view showing the second barrel.

6A is a plan view, FIG. 6B is a vertical sectional view, FIG. 6C is a left side view, and FIG. 6D is a right side view showing the third barrel.

FIG. 7 (a) is a plan view showing upper and lower gantry and main support,
(B) It is a longitudinal cross-sectional view.

8A is a left side view and FIG. 8B is a right side view showing upper and lower mounts and a main support.

9A is a plan view, FIG. 9B is a longitudinal sectional view, FIG. 9C is a left side view, and FIG.

FIG. 10 is an explanatory diagram illustrating a relationship between a rotation center of an imaging optical system and an image shift.

[Reference Numerals] R ... reticle W ... wafer A ... first imaging optical system A ₁ ... front group A ₂ ... rear group S ... intermediate image M _C ... concave mirror M _1, M ₂ ... plane mirror B ... second imaging optics AS ... aperture stop z _1, z _2, z ₃ ... optical axis X ... front-back direction Y ... lateral direction Z ... vertically 1 ... first barrel 1a ... flange 2 ... second barrel 3 ... third barrel 3a ... flange 5 Lower frame 6a-6d Main column 7 Upper frame 8a, 8b Auxiliary column

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA21 LA01 NA04 RA05 RA32 TA01 TA05 UA03 UA04 5F046 BA05 CB02 CB05 CB12 CB20 CB25

Claims (6)

[Claims] 1. A catadioptric projection exposure apparatus for forming an image on a first surface on a second surface using an optical member including a refractive optical member, a curved mirror, and an optical path deflecting member, wherein the number of the exposure devices is two or more. Of the optical path deflecting member and N (N ≧
3) having one or more optical axes, and holding one or a plurality of the optical members arranged on the individual optical axes in a barrel, so that M (M ≧ M)
N) barrels, at least one of the M barrels holds two of the optical path deflecting members, and has an optical axis before and after being bent by the two optical path deflecting members. Holding both optical path deflecting members so as to be parallel to each other; at least one of the other barrels of the M barrels holds only the refractive optical member, or the refractive optical member and the curved mirror A catadioptric projection exposure apparatus, characterized in that it holds only one of them. 2. The catadioptric projection exposure apparatus according to claim 1, wherein the N optical axes are arranged in a vertical direction or a horizontal direction, respectively. 3. The catadioptric projection according to claim 1, wherein the exposure apparatus has a single mount, and the M barrels are supported by the mount independently of each other. Exposure equipment. 4. The exposure apparatus has a gantry, and a barrel holding only the refractive optical member or holding only the refractive optical member and the curved mirror has an imaging magnification β of the optical member held by the barrel. Wherein the optical member is supported by the mount on or near a plane that internally divides the distance from the object plane to the image plane at a ratio of 1: (− β). 4. The catadioptric projection exposure apparatus according to 1, 2, or 3. 5. An exposure apparatus comprising: a first imaging optical system for forming an intermediate image of the first surface; and a second imaging optical system for forming a re-image of the intermediate image on the second surface. And a first optical path deflecting member disposed near the intermediate image, and disposed between the first optical path deflecting member and the second imaging optical system or disposed inside the second imaging optical system. A second optical path deflecting member, and first, second and third barrels, wherein the first imaging optical system is held by the first barrel, and the first optical path deflecting member and the second optical path deflecting member And the optical member disposed between these optical path deflecting members is held by the second barrel, and is disposed closer to the second surface than the second optical path deflecting member except for the second optical path deflecting member. 5. The optical member according to claim 1, wherein said optical member is held by said third barrel. Catadioptric projection exposure apparatus. 6. The first imaging optical system includes the curved mirror,
The catadioptric projection exposure apparatus according to claim 5, wherein the curved mirror is formed by a concave mirror.