KR102253410B1 - Illumination optical system, exposure apparatus, and method of manufacturing article - Google Patents

Abstract

It provides a technique for controlling the exposure wavelength which is advantageous in terms of CD uniformity.
An illumination optical system for illuminating the surface to be illuminated is provided. The illumination optical system includes a light-shielding plate forming an opening defining the shape of an illumination area on the surface to be illuminated, an adjustment unit for adjusting the light-shielding plate to change the illumination area on the surface to be illuminated, and illuminating the surface to be illuminated. It has a wavelength selector for selecting a wavelength of light, and the adjustment unit changes the illumination region using a light shielding plate according to a wavelength selected by the wavelength selector.

Description

Lighting optical system, exposure apparatus, and article manufacturing method {ILLUMINATION OPTICAL SYSTEM, EXPOSURE APPARATUS, AND METHOD OF MANUFACTURING ARTICLE}

The present invention relates to an illumination optical system, an exposure apparatus, and an article manufacturing method.

In the exposure apparatus, in a lithography process, which is a manufacturing process of a semiconductor device or a liquid crystal display device, a pattern of an original plate (reticle, mask) is applied to a photosensitive substrate (a wafer or glass plate with a resist layer formed on the surface thereof) through a projection optical system. It is a device that transfers to. Regarding the resolution performance of the exposure apparatus, a formula called Rayleigh's equation is known.

RP=k ₁ λ/NA (1)

However, RP represents the resolution, λ represents the exposure wavelength, NA represents the numerical aperture of the projection optical system, and k ₁ represents the dimensionless quantity representing the difficulty of the resolution. The smaller the value of the resolution RP, the finer exposure is possible. From equation (1), it can be seen that as one of the methods of reducing RP, short exposure wavelength λ is sufficient.

On the other hand, the depth of focus DOF of the exposure apparatus is expressed by the following equation.

DOF=k₂λ/NA² (2)

_{Like k 1} , k _{2 is} also a dimensionless quantity and varies depending on the type of resist material or the lighting conditions for illuminating the original plate. From equation (2), it can be seen that one of the methods of increasing the depth of focus DOF is to increase the exposure wavelength λ.

As described above, the exposure wavelength λ affects the resolution RP and the depth of focus DOF, and exposure performance can be adjusted by changing the exposure wavelength λ.

Hereinafter, a specific example is given. For example, suppose an ultra-high pressure mercury lamp is used as a light source of an exposure apparatus. Although the wavelength of light output from the light source varies, exposure apparatuses for manufacturing flat panel displays (FPD) or the like generally extract and use light having a wavelength of 250 nm to 500 nm.

For example, when the resolving power of the apparatus is insufficient, a wavelength filter that cuts the long wavelength side may be inserted into the illumination optical system of the exposure apparatus. Thereby, the average wavelength of light used for exposure can be shortened, and the resolving power can be improved.

On the other hand, suppose that the resolving power is sufficient, and it is desired to reduce the allowable out-of-focus in the exposure process for the development process. In this case, contrary to the above, a wavelength filter that cuts the short wavelength side of the light from the light source may be inserted into the illumination optical system of the exposure apparatus. By doing so, you can increase the depth of focus.

However, by changing the exposure wavelength, when there is chromatic aberration in the lens in the illumination optical system, the illumination distribution of the surface to be illuminated is changed, and uneven illumination distribution (hereinafter referred to as ``illuminance non-uniformity'') occurs in the exposure area. The unevenness of illuminance in the exposure region becomes one of the factors that deteriorate the CD uniformity (Critical Dimension Uniformity) when the pattern of the original plate is engraved on the substrate. The CD uniformity is the degree of variation in the size and length of the pattern in the exposed area, and the smaller the variation is, the better the exposure performance is.

A technique for correcting the deterioration of CD uniformity due to occurrence of uneven illumination is disclosed in Japanese Patent Laid-Open No. 62-193125. In Patent Document 1, the exposure amount is adjusted by changing the slit width, and CD is corrected. By pushing or pulling the plate for determining the slit width with a piezo element or the like, the slit width can be changed for each slit location.

However, in the method of Japanese Patent Laid-Open No. 62-193125, it is possible to cope with minute corrections caused by manufacturing fluctuations, such as assembly errors of each optical element in the illumination optical system, and transmittance fluctuations in the projection optical system. Correction is difficult. If extensive correction is repeatedly performed, there is a possibility that the plate is deformed according to the change over time, the correction accuracy is deteriorated, and the correction mechanism itself cannot be used. Even if the stiffness of the plate is increased, the amount that can be corrected is limited, and in the end, it is difficult to make a large correction due to a change in the exposure wavelength.

According to an aspect of the present invention, an illumination optical system for illuminating a surface to be illuminated, a light shielding plate forming an opening defining a shape of an illuminated region on the surface to be illuminated, and the illuminated region on the surface to be illuminated, And a wavelength selector for selecting a wavelength of light that illuminates the surface to be illuminated, and the adjustment unit includes the light shielding plate according to the wavelength selected by the wavelength selector. There is provided an illumination optical system characterized in that the area is changed.

1 is a diagram showing a configuration of an illumination optical system in an embodiment.
Fig. 2 is a diagram showing a configuration of a fly-eye optical system in an embodiment.
3 is a diagram showing a configuration of a slit mechanism in an embodiment.
4 is a diagram for explaining control of a slit mechanism in an embodiment.
5 is a diagram showing a configuration of an illumination optical system in an embodiment.
6 is a diagram showing a configuration of a fly-eye optical system in an embodiment.
Fig. 7 is a diagram showing a configuration of an aperture stop in an embodiment.
Fig. 8 is a diagram showing a configuration of a slit in an embodiment.
9 is a diagram showing a configuration of an exposure apparatus in an embodiment.
It is a figure explaining the measurement operation of illuminance non-uniformity.
Fig. 11 is a diagram for explaining correction of illuminance non-uniformity.
12 is a flowchart of a method of correcting illuminance non-uniformity.
Fig. 13 is a diagram for explaining correction of illuminance non-uniformity.
Fig. 14 is a diagram showing a modified example of a slit mechanism.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First embodiment>

1 is a schematic diagram showing the configuration of an illumination optical system according to the present embodiment. The illumination optical system 100 may be mounted on an exposure apparatus, for example, and illuminates a mask (original plate) on which a pattern, which is a surface to be illuminated, is formed with light from a light source unit.

The light source unit 120 includes a light source 101, an elliptical mirror 102, a plurality of wavelength filters 104a and 104b, and a first optical system 105. As the light source 101, a high-pressure mercury lamp is used, for example. In addition to the high-pressure mercury lamp, a xenon lamp or an excimer laser may be used. The elliptical mirror 102 is a condensing optical system for condensing light emitted from the light source 101. The light source 101 is disposed at one of the two focal positions of the ellipse. The light exiting from the light source 101 and reflected by the elliptical mirror 102 is condensed at the other focal position of the ellipse and passes through a wavelength filter 104a disposed in the vicinity thereof.

The wavelength filter 104b is located in the vicinity of the wavelength filter 104a. The plurality of wavelength filters 104a and 104b are a plurality of wavelength filters that transmit light having different wavelengths from each other, and are configured so that the wavelength filters to be used can be switched. Thereby, the exposure wavelength can be selected. Further, the wavelength filters 104a and 104b may be constituted by a dielectric multilayer film, for example. The wavelength selection unit 51 arranges a wavelength filter selected from among the plurality of wavelength filters 104a and 104b in the optical path between the light source unit and the surface to be illuminated. Since the wavelength selection unit 51 is connected to the control unit 50, a wavelength filter to be used can be designated (selected) by the control unit 50.

The light that has passed through the wavelength filter 104a is guided by the first optical system 105 to the deflecting mirror 107 and reaches the synthesis unit 108. The first optical system 105 is arranged so that the synthesis unit 108 is substantially a Fourier transform position of the emission surface of the wavelength filter 104a or 104b.

In addition, in the example of FIG. 1, there are two light source parts 120, and the deflection mirror 107 is arrange|positioned with respect to each light source part. The arrangement of the deflecting mirrors differs depending on the number of light source units, but the number of light source units may be one or three or more.

The light emitted from the synthesis unit 108 is guided by the second optical system 140 to the fly-eye optical system 109 constituting an optical integrator for uniformly illuminating the surface to be illuminated. Here, the second optical system 140 is arranged so that the incident surface of the fly-eye optical system 109 is substantially the Fourier transform position of the synthesis unit 108.

2 is a diagram showing a configuration example of the fly-eye optical system 109. As shown in FIG. As shown in FIG. 2, the fly-eye optical system 109 has two lens groups 131 and 132, in which a plurality of plano-convex lenses are joined in a planar shape. The lens groups 131 and 132 are arranged with the curved surfaces facing each other so that the paired plano-convex lenses are positioned at the focal positions of the individual plano-convex lenses. By using such a fly-eye optical system 109, a plurality of secondary light source images equivalent to the light source 101 are formed at the position of the exit surface of the fly-eye optical system 109.

Immediately below the fly-eye optical system 109, an aperture stop 110 (? aperture) is provided. The light flux passing through the aperture stop 110 is guided to the slit mechanism 181 by the third optical system 150. At this time, the third optical system 150 is arranged so that the slit mechanism 181 substantially becomes a Fourier transform surface of the exit surface of the fly-eye optical system 109.

3 shows an example of the configuration of the slit mechanism 181. The slit mechanism 181 includes a first light blocking plate 171 in which an opening 172 defining the shape of an illuminated area on the surface to be illuminated is formed, and a first light blocking plate 171 to change the illumination area on the surface to be illuminated. It has an adjustment part 90 which performs the adjustment of. The opening 172 is, for example, an arc-shaped slit through which light passes. The adjustment unit 90 includes a first adjustment unit 52 that adjusts the position of the first shading plate 171 in the Y direction (first direction), and a second adjustment unit 52 that adjusts the shape of the opening 172 in the Y direction. It may include an adjustment unit 173. The first adjustment unit 52 includes an actuator. The first adjustment unit 52 is connected to the control unit 50, and the operation of the first adjustment unit 52 may be controlled by the control unit 50. The first light shielding plate 171 is a member for changing the position of the boundary on the upstream side and the downstream side in the Y direction in the illumination region. By changing the position in the Y direction of the first light shielding plate 171 (opening part 172) by the first adjustment unit 52, the position of the boundary on the upstream side and the downstream side in the Y direction in the illumination area is changed. do. A second light shielding plate 170 is formed at one end of the opening 172 forming an arc shape. The second light shielding plate 170 is a member for changing the shape of the boundary on the downstream side in the Y direction in the illumination region. The second shading plate 170 is provided with a second adjusting portion 173 (pressing portion) that pushes or pulls each position of the second shading plate 170 in the X direction (the second direction) in the Y direction. The second adjustment unit 173 may be a plurality of actuators. Each of these actuators is connected to the control unit 50 via a wiring 174. Thereby, the plurality of actuators are driven by the control of the control unit 50, respectively. By driving the actuator of the second adjustment unit 173, the shape of the end portion of the second light shielding plate 170 is changed, so that the shape of the boundary on the downstream side in the Y direction in the illumination region is changed. Moreover, you may arrange|position so that the 2nd light shielding plate 170 may change the shape of the boundary on the upstream side of the Y direction in an illumination area. 14 shows a configuration example of the slit mechanism 182 which is a modified example of the slit mechanism 181. In the example of FIG. 14, the first light blocking plate 171 of FIG. 3 is divided into two light blocking members 175 and 176. The light blocking member 175 is a member that defines the position of the boundary on the upstream side of the opening 172 in the Y direction. The light blocking member 176 is a member defining a boundary between both ends of the opening 172 in the X direction. The adjustment unit 91 has a position adjustment unit 53 that adjusts the position of the light blocking member 175 in the Y direction. The position adjustment unit 53 includes an actuator. By changing the position of the light blocking member 175 in the Y direction by the position adjustment unit 53, the position of the upstream boundary in the Y direction in the illumination region is changed.

The arc-shaped light beam that has passed through the opening 172 is illuminated by the third optical system 160 to the mask M. The mask M is illuminated while moving in the Y direction (first direction). In addition, in the example of FIG. 3 and FIG. 14, although the opening 172 used what has an arc shape, it may be another shape, for example, a rectangle.

(Design example)

Hereinafter, a design example in the first embodiment will be described.

The wavelength filter 104a is, for example, a wavelength filter that allows only light in the vicinity of the i-line (365 nm) among the light emitted from the light source to pass. FIG. 4A1 is a view when the opening 172 of the slit mechanism 181 is viewed from the traveling direction of light. The light emitted from the exit surface of the fly-eye optical system 109 is irradiated almost uniformly to the slit mechanism 181 by the third optical system 150, but due to the aberration of the third optical system 150, (A1 of FIG. 4) The roughness unevenness as indicated by the circular contour line of) occurs. Here, when the energy of light is integrated in the scanning direction (Y direction) perpendicular to the X direction, it becomes as shown in FIG. 4A2 according to the illuminance non-uniformity in FIG. 4A1. What is desired is that there is no irregularity in illuminance, that is, that the accumulated energy I does not fluctuate in the X direction.

Subsequently, the control unit 50 controls the wavelength selection unit 51 to switch the wavelength filter disposed in the optical path from the wavelength filter 104a to the wavelength filter 104b. The wavelength filter 104b is a wavelength filter that allows only light in the vicinity of the g-line (435 nm) among the light emitted from the light source to pass. At this time, due to the influence of the chromatic aberration of the third optical system 150, unevenness of illumination as indicated by the circular contour line of FIG. 4B1 occurs. Fig. 4B2 shows the accumulated energy I obtained by integrating the energy of light in the scanning direction (Y direction).

Fig. 4B1 shows that since the wavelength of light entering the third optical system 150 was changed by switching to the wavelength filter 104b, the illuminance unevenness increased. As a result, as shown in Fig. 4B2, the difference in the accumulated energy I of light is large depending on the position in the X direction.

Thus, the control unit 50 controls the first adjustment unit 52 to drive the light shielding plate 171 to shift the position of the opening 172 in the scanning direction (Y direction). 4(C1) shows a state after the opening 172 is shifted. It can be seen that compared to FIG. 4B1, the number of openings 172 over the contour lines of the illuminance distribution has been reduced. Thereby, as shown in FIG. 4C2, the difference by the position of the X direction of the accumulated energy I can be made small.

In this way, the adjustment unit 90 adjusts the light shielding plate 171 according to which wavelength filter is used. In addition, instead of driving the light shielding plate 171 by the first adjustment unit 52, the shape of the end portion of the opening 172 in the Y direction may be adjusted by the second adjustment unit 173. Alternatively, both the first adjustment unit 52 and the second adjustment unit 173 may be adjusted.

Further, a configuration in which a plurality of light shielding plates having different openings in shape from each other is provided, and the light shielding plate to be used is appropriately switched according to the wavelength filter to be used is also conceivable. For example, the adjustment unit 90 adjusts the positions of the plurality of light-shielding plates so that the light-shielding plate corresponding to the wavelength filter used among the plurality of light-shielding plates is disposed in the optical path between the wavelength filter and the surface to be illuminated. This specific form will be described in the following second embodiment.

<2nd embodiment>

5 is a diagram showing a configuration of an illumination optical system 200 according to a second embodiment. The same reference numerals are attached to the same constituent elements as those in Fig. 1 according to the first embodiment, and their descriptions are omitted.

The light source unit 121 includes a light source 210, an elliptical mirror 102, and a first optical system 105. In this embodiment, the light source 210 can be switched to the light source 211 located in the vicinity thereof. The light source 210 and the light source 211 are configured to emit light having different wavelengths from each other. The light source selection unit 61 (wavelength selection unit) performs switching driving so that a light source selected from a plurality of light sources (the light source 210 and the light source 211) is disposed at a predetermined light source position. Since the light source selection unit 61 is connected to the control unit 60, the light source to be used can be designated (selected) by the control unit 60. In the example of FIG. 5 as well as in FIG. 1, two light source units are shown, but the number of light source units may be one or three or more.

The light emitted from the synthesis unit 108 is guided by the second optical system 140 to the fly-eye optical system 109, which is an optical integrator for uniformly illuminating the surface to be illuminated. In the vicinity of the incident side of the fly-eye optical system 109, a wavelength filter 220 is disposed in the optical path. Here, the second optical system 140 is arranged so that the incident surface of the fly-eye optical system 109 is substantially the Fourier transform position of the synthesis unit 108. A fly-eye optical system 111 is disposed in the vicinity of the fly-eye optical system 109, and is configured to be switchable with the fly-eye optical system 109. The integrator selection unit 62 arranges an optical integrator selected from among a plurality of optical integrators (fly-eye optical system 109 and fly-eye optical system 111) in the optical path. Since the integrator selection unit 62 is connected to the control unit 60, the optical integrator to be used can be designated (selected) by the control unit 60.

6 is a diagram showing a configuration example of the fly-eye optical system 111. The fly-eye optical system 111 has lens groups 133 and 134. The lens groups 133 and 134 are disposed so that the paired plano-convex lenses are positioned at the focal positions of the individual plano-convex lenses, so as to face the curved surfaces. Each of the plano-convex lenses constituting the lens groups 133 and 134 is constituted by a lens having a different curvature than the individual plano-convex lenses constituting the lens groups 131 and 132 of FIG. 2. For this reason, the angles (emission angles) of light emitted from the fly-eye optical systems 109 and 111 are different from each other.

The light beam emitted from the exit surface of the fly-eye optical system 109 is guided by the third optical system 150 to the slit of the light-shielding plate 242 (third light-shielding plate). At this time, the third optical system 150 is disposed so that the light shielding plate 242 substantially becomes a Fourier transform surface of the exit surface of the fly-eye optical system 109.

Further, in the vicinity of the exit surface of the fly-eye optical system 109, an aperture stop 231 is disposed. Further, the aperture stop 232 is disposed in the vicinity of the aperture stop 231, so that it can be switched to the aperture stop 231. This makes it possible to change the lighting mode. The aperture stop selector 63 arranges an aperture stop selected from among a plurality of aperture stop (the aperture stop 231 and the aperture stop 232) in the optical path. Since the aperture stop selector 63 is connected to the control unit 60, the aperture stop to be used can be designated (selected) by the control unit 60.

In the vicinity of the light-shielding plate 242, a light-shielding plate 241 and a light-shielding plate 243, each having an opening (slit) of a different shape, are disposed, and the light-shielding plate used between the plurality of light-shielding plates 241, 242, 243 is switched. It is possible. The openings of each of the light shielding plates 241, 242, 243 are shaped in consideration of conditions such as the exposure wavelength, the exit angle of the fly-eye optical system, and the illumination mode. The light shielding plate selection unit 64 performs an operation corresponding to the adjustment unit 90 in the first embodiment. The light shielding plate selection unit 64 arranges a light shielding plate selected from among the plurality of light shielding plates 241, 242, 243 in the optical path. Since the light shielding plate selection unit 64 is connected to the control unit 60, the light shielding plate to be used can be designated (selected) by the control unit 60.

(Design example)

Hereinafter, a design example in the second embodiment will be described.

The light source 210 and the light source 211 are, for example, ultra-high pressure mercury lamps. However, the light source 211 is a light source (for example, a DUV lamp) having a stronger light intensity on the shorter wavelength side of 350 nm or less compared to the light source 210.

The wavelength filter 220 is a wavelength filter having an intensity center wavelength of 300 nm among light output from a light source. In addition, the intensity center wavelength means a wavelength calculated by calculating the center of gravity of the light intensity using the wavelength as a variable. On the other hand, the wavelength filter 221 is a wavelength filter whose intensity center wavelength is 405 nm among the light output from the light source.

In the aperture stop 231 and the aperture stop 232, the shapes of the apertures are different from each other. The aperture stop 231 is an aperture stop that passes light in a ring shape as shown in Fig. 7A. On the other hand, the aperture stop 232 is an aperture stop that passes light in a normal circular shape, as shown in FIG. 7B.

8 is a diagram showing a configuration example of a slit (opening portion) of each light shielding plate 241, 242, 243. As shown in FIG. The light shielding plate 241 has an arc-shaped slit. The curvatures of the outer arc 241-O and the inner arc 241-I are the same, respectively. The light shielding plate 242 also has an arc-shaped slit. However, the curvature of the outer arc 242-O and the inner arc 242-I differ by about 1%, for example. The light shielding plate 243 also has an arc-shaped slit. The outer arc 243-O and the inner arc 243-I have the same curvature, but the curvatures of 241-O and 241-I are different. In addition, although not shown in FIG. 8, the light shielding plates 241, 242, 243 may also be provided with a mechanism for adjusting the opening width of the opening, like the slit mechanism 181 of FIG. 3, respectively.

The light shielding plates 241 to 243 are used in combinations of exposure wavelengths, integrators, aperture stop, and slits as shown in patterns 1 to 8 shown in Table 1 below. In Table 1, the integrator, aperture stop, and light shielding plate (slit) are indicated by reference numerals in Figs. 5 to 8, respectively.

For example, patterns 1 and 3 have a shorter exposure wavelength and an annular shape (Fig. 7 (A)) for the aperture stop, resulting in uneven illumination in which the illumination decreases from the center of the slit to the outside of the slit in the X direction. do. So, in this case, the light shielding plate 242 having an opening widening toward the outside in the X direction is used. Thereby, the energy integration value of the light in the Y direction is less likely to generate a difference due to the position in the X direction.

In addition, for example, in the case of patterns 6 and 8, since a small circle shape (Fig. 7(B)) was used for the longer exposure wavelength and the aperture stop, the illuminance increased from the center of the slit to the outside of the slit in the X direction. Irradiance unevenness occurs. So, in this case, the light shielding plate 243 is used.

As shown in FIG. 8, in the light shielding plate 241 and the light shielding plate 243, the radius of curvature of the circular arc shape of the slit is different. The shading plate 243 is designed to have a smaller radius of curvature than the shading plate 241. By doing so, the energy integrated value of the light in the Y direction is less likely to cause a difference due to the position in the X direction.

For example, in FIG. 8, since the position difference in the Y direction is small between the positions 241L, 241C, and 241R of the opening of the light shielding plate 241 in the X direction, a difference in the energy integration value is likely to occur due to the X position. On the other hand, between the positions 243L, 243C, and 243R of the opening of the light shielding plate 243 in the X direction, the position difference in the Y direction is large.

In addition, in the present embodiment as well, the case where the shape of the opening is made into an arc shape has been described, but it may be, for example, a rectangular shape instead of an arc shape. When the shape of the opening is made into a rectangle, the same effect as in the case of an arc opening can be obtained by substituting the above-described arc curvature with a rectangular inclination.

<Embodiment of exposure apparatus>

Hereinafter, an embodiment of an exposure apparatus including the illumination optical system 100 according to the first embodiment will be described. Since the same description can be made for an exposure apparatus having the illumination optical system 200 according to the second embodiment instead of the illumination optical system 100, an exposure apparatus having the illumination optical system 100 is typically described below.

9 is a diagram showing a configuration of an exposure apparatus 400 according to an embodiment. The exposure apparatus 400 includes an illumination optical system 100 and scans and exposes a substrate by slit light from the illumination optical system 100. The illumination optical system 100 is provided with the slit mechanism 181 which can adjust the shape of the opening part mentioned above.

The exposure apparatus 400 includes a mask stage 300 for holding a mask M, a projection optical system 301 for projecting a pattern of the mask M onto a substrate, and a substrate stage 302 for holding the substrate. The projection optical system 301 is, for example, a projection optical system in which a first concave reflective surface 71, a convex reflective surface 72, and a second concave reflective surface 73 are arranged in order in an optical path from an object surface to an image surface. to be.

The exposure apparatus 400 further includes a measurement unit 304 that measures the illuminance non-uniformity in the exposed region on the substrate by measuring the illuminance distribution of light reaching the substrate stage 302. Further, a slit 303 is interposed between the substrate stage 302 and the measurement unit 304. The slit 303 may be scanned and driven in a direction (X direction) along a surface of the substrate stage 302 on which a substrate is mounted by the driving unit 303a under the control of the controller 80.

As shown in FIG. 9, the measurement unit 304 includes a sensor 305 and an optical system 306 for guiding the light passing through the slit 303 to the sensor 305. The operation of the measurement unit 304 is as follows.

As shown in Fig. 10, the slit 303 is scanned in the X direction with respect to the region 401 of light to be imaged on the substrate stage 302. As shown in FIG. At this time, of the light formed on the region 401, only the light formed on the opening 307 of the slit 303 enters the measurement unit 304. The light incident into the measurement unit 304 is guided to the sensor 305 through the optical system 306. While scanning the slit 303 in the X direction, by reading the energy of light reaching the sensor 305, the illuminance is measured for each position in the region 401. Thereby, it is possible to calculate the illuminance non-uniformity.

As described above, by adjusting the opening width of the slit mechanism 181 of the illumination optical system 100, it is possible to reduce uneven illumination. For example, it is assumed that the illuminance unevenness as shown in Fig. 11A is measured by the measurement unit 304. In this case, by locally widening the width of the slit mechanism 181 in the portion where the illuminance is lowered, and locally narrowing the width of the slit mechanism 181 in the portion where the illuminance is increased, as shown in FIG. Likewise, the illuminance distribution can be made uniform.

(Example of illuminance unevenness correction)

Hereinafter, correction of the illuminance unevenness according to the present embodiment will be described.

12 is a flowchart of a method for correcting illuminance unevenness in the present embodiment. As step S1, a simulation of illuminance non-uniformity is performed in advance for each setting of the exposure wavelength, the integrator, and the aperture stop. Next, based on the simulation result of step S1, the opening shape as a reference of the slit mechanism 181 for each setting is determined (step S2). The opening shape as a reference of the slit mechanism 181 is preferably an opening shape that reduces unevenness in illuminance. For example, it is assumed that the illuminance unevenness as shown in Fig. 13A is expected by the simulation in step S1. At this time, by appropriately setting the radius of curvature of the circular arc as the base, the roughness distribution as shown in Fig. 13B can be corrected.

Next, in the exposure apparatus 400, the control unit 80 measures the illuminance non-uniformity using the measurement unit 304 for each slit having the opening shape determined in step S2 (step S3). The illuminance unevenness measured at this time is expected to be a distribution as shown in Fig. 13B.

However, the actual illuminance distribution accumulates an assembly error in the manufacture of the device, and may result in a locally uneven distribution as shown in Fig. 13C. Therefore, as step S4, the control unit 80 corrects this local illumination unevenness by locally driving the opening width of the opening 172 of the slit mechanism 181 using a plurality of actuators 173. Thereby, as shown in Fig. 13D, it is possible to reduce the illumination unevenness in the X direction, and further improve the CD uniformity of the exposure apparatus.

<Embodiment of an article manufacturing method>

The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing an article such as a micro device such as a semiconductor device or an element having a fine structure. The article manufacturing method of this embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate by using the above-described exposure apparatus (a step of exposing the substrate), and a step of developing a substrate on which the latent image pattern is formed in this step. Includes. In addition, such a manufacturing method includes other well-known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist peeling, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared to the conventional method.

The present invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the spirit and scope of the present invention. Accordingly, the following claims are appended in order to disclose the scope of the present invention.

Claims (14)

It is an illumination optical system that illuminates the surface to be illuminated,
A light shielding plate forming an opening defined by a first curve and a second curve, as an opening defining a shape of an illumination area on the illuminated surface;
By changing the curvature of the first curve or the curvature of the second curve in the light shielding plate to make the curvature of the first curve and the curvature of the second curve different, the illumination area on the surface to be illuminated is changed. An adjustment unit that adjusts the shading plate so as to be changed,
It has a wavelength selector for selecting a wavelength of light illuminating the surface to be illuminated,
The illumination optical system, characterized in that the adjustment unit changes the illumination area so that illumination unevenness due to chromatic aberration occurring in a lens included in the illumination optical system is reduced by light having a wavelength selected by the wavelength selection unit. The method of claim 1,
The illumination optical system illuminates a surface to be illuminated of the mask while moving the mask in a first direction,
The adjustment unit, according to the wavelength selected by the wavelength selection unit, using the light shielding plate to change a position of a boundary before or after the first direction in the illumination region. The method of claim 2,
The light blocking plate includes a first light blocking plate for changing a position of a boundary of an upstream side or a downstream side of the first direction in the illumination area, and an upstream side or a downstream side of the first direction in the illumination area. It has a second shading plate for changing the shape of the boundary,
The adjustment unit, according to the wavelength selected by the wavelength selection unit, characterized in that using the first light shielding plate to change the position of the boundary of the upstream side and the downstream side in the first direction in the illumination region. , Illumination optical system. The method of claim 3,
The adjustment unit includes a first adjustment unit for adjusting a position of the first light blocking plate in the first direction, and a second adjusting unit for adjusting a shape of the second light blocking plate. The method of claim 1,
In order to illuminate the surface to be illuminated, further comprising an integrator selection unit for arranging an optical integrator selected from a plurality of optical integrators having different exit angles in the optical path,
The adjustment unit, according to the optical integrator disposed in the optical path, characterized in that the light shielding plate to change the illumination area, characterized in that the illumination optical system. The method of claim 1,
Further comprising an aperture stop selector for arranging an aperture stop selected from among a plurality of aperture stops having different opening shapes in the optical path,
An illumination optical system, characterized in that the illumination area is changed using the light blocking plate according to the aperture stop disposed in the optical path. The method of claim 1,
An illumination optical system, characterized in that the wavelength selector has a plurality of wavelength filters that transmit light having different wavelengths from each other, and a wavelength filter selected from the plurality of wavelength filters is arranged in an optical path. The method of claim 1,
The wavelength selection unit, an illumination optical system, characterized in that it has a plurality of light source units for emitting light of different wavelengths from each other. The method of claim 1,
The opening is an opening defined by a first arc and a second arc,
The adjusting unit may change the curvature of the first arc or the second arc of the light shielding plate according to the wavelength selected by the wavelength selection unit, and thus the curvature of the first arc and the second arc The illumination optical system, characterized in that by changing the curvature, the illumination area is changed. The illumination optical system according to any one of claims 1 to 9 for illuminating the mask, and
An exposure apparatus, comprising: a projection optical system that projects an image of the pattern of the mask onto a substrate. The method of claim 10,
Further comprising a measurement unit for measuring the non-uniformity of the illuminance distribution in the exposed region on the substrate,
The exposure apparatus, wherein the adjustment unit changes the illumination area using the light-shielding plate based on a non-uniformity in the illuminance distribution measured by the measurement unit. A step of exposing a substrate using the exposure apparatus according to claim 11, and
Including a process of developing the substrate exposed in the process,
An article manufacturing method, characterized in that the article is manufactured from the developed substrate. delete delete

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