JPH11288874A - Exposure apparatus and exposure method - Google Patents

Abstract

(57) [Problem] To be configured so that a pattern formed of a minute light-shielding portion formed in a dimming region of a mask blind and a foreign matter adhering to the mask blind are unlikely to cause transfer to a photosensitive substrate and uneven exposure light amount. Exposure equipment. SOLUTION: An illumination area defining means (9) has a drive system (23, 24) for moving each of a plurality of blind members (21, 22) along a predetermined direction. Each blind member has a light-transmitting region, a light-blocking region, and a light-reducing region. In order to make the amount of exposure light substantially the same between the overlapping exposure area that partially overlaps and the other exposure area, the darkened area of each blind member has a predetermined transmittance distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and an exposure method, and more particularly to an exposure apparatus used for manufacturing a semiconductor device, a liquid crystal display device, etc., in which a unit mask pattern is partially overlapped on a photosensitive substrate. The present invention relates to an exposure apparatus that forms a large-area pattern, that is, an exposure apparatus that performs so-called screen synthesis.

[0002]

2. Description of the Related Art Conventionally, in this type of exposure apparatus, in order to cope with an increase in the size of a photosensitive substrate to be exposed, an exposure region of the photosensitive substrate is divided into a plurality of unit exposure regions, and each unit exposure region is divided into a plurality of unit exposure regions. Is repeated a plurality of times to finally synthesize a pattern having a desired large area, that is, a screen synthesis method. When synthesizing screens, pattern breaks occur at the boundary position of each unit exposure area due to drawing errors of the mask for pattern projection, distortion of the projection optical system, positioning errors of the stage for positioning the photosensitive substrate, etc. Easy to do. Therefore,
In order to prevent the occurrence of pattern breaks, exposure for screen synthesis is performed by overlapping the boundaries of each unit exposure area by a very small amount, in other words, by partially overlapping each unit exposure area. I have.

However, when the unit exposure areas are partially overlapped, the exposure light quantity of the overlapped exposure area (hereinafter referred to as "overlapping exposure area") is twice as large as the exposure area other than the overlapping exposure area (four overlapping exposure areas). (4 times in the area), and the line width at the joint of the pattern greatly changes depending on the characteristics of the photosensitive agent and the pattern properties. Further, when screen synthesis is performed, a step may occur at a joint portion of a pattern due to a relative positional shift between two adjacent unit exposure areas, and characteristics of a manufacturing device may be impaired. Furthermore, when the pattern formation of each layer is assigned to a different exposure apparatus in the process of superimposing the single-layer pattern synthesized on the screen into a plurality of layers, the unit exposure in each layer depends on the lens distortion of each exposure apparatus and the difference in the positioning error of the stage. The superimposition error of the area changes discontinuously at the joint of the pattern. In this case, especially in an active matrix liquid crystal device, the contrast is discontinuously changed at a pattern joint portion, and the quality of the device is degraded.

Japanese Patent Application Laid-Open Nos. Hei 6-244077 and Hei 7-235466 disclose an exposure apparatus which solves the above-described inconvenience in screen composition. In the exposure apparatuses described in these publications, a masking blind which is arranged at a position substantially conjugate with the mask and defines an illumination area of the mask has a light-shielding region in which the transmittance linearly changes from 100% to 0%. Is formed over a width of several mm. Then, by the effect of the light-reducing region, the exposure light amount is made substantially equal between the overlapping exposure region and the other exposure region. In particular, JP-A-7-235466 described above
In the exposure apparatus disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, a dimming region is formed by forming a dot-shaped minute light-shielding portion having a size equal to or smaller than the limit resolution of the exposure device according to a predetermined density distribution. That is, the density distribution of the minute light-shielding portions in the darkening region is set to increase linearly from the light-transmitting region side to the light-shielding region side.

In the exposure apparatuses described in the above two publications, it is necessary to dispose the mask blind at a position conjugate with the mask or in the vicinity thereof. For this reason, when a minute foreign matter having a predetermined size or more adheres to the mask blind, there is a possibility that the minute foreign matter is transferred onto the photosensitive substrate and causes a defect in a manufacturing device. Therefore, Japanese Patent Application Laid-Open No.
Japanese Patent Publication No. 66 proposes an exposure apparatus provided with a foreign matter inspection mechanism for irradiating a light beam to a mask blind disposed at a position substantially conjugate with a mask and detecting a reflected light beam from the mask blind. In this exposure apparatus, a foreign substance inspection mechanism having a simple configuration can periodically inspect foreign substances based on optical information from a mask blind, so that the transfer of foreign substances to a photosensitive substrate can be prevented beforehand. Can be.

[0006]

However, as disclosed in Japanese Patent Application Laid-Open No. 7-235466, the width of the dimming region formed in the mask blind is several millimeters, and the width of this dimming region is as narrow as several millimeters. It is difficult to linearly change the transmittance from 0% to 100% by forming a dot-shaped minute light-shielding portion according to a predetermined density distribution. In addition, since the exposure is performed without moving the mask blind, which is disposed almost conjugate with the mask (and, consequently, the photosensitive substrate), the pattern itself consisting of the dot-shaped minute light-shielding portions formed in the dimming region is transferred to the photosensitive substrate. There is a possibility that it will be reflected. In the above-mentioned publication, it is proposed to form a dot-shaped minute light-shielding portion having a size equal to or smaller than the limit resolution of the exposure apparatus according to a predetermined density distribution. There is a possibility that the reflection of the pattern itself may occur, which may lead to uneven illuminance. That is,
Due to the effect of the pattern of minute light-shielding portions in the form of dots formed on the mask blind, not only does the exposure light amount differ substantially between the overlapping exposure area and the other exposure areas, but also the exposure light quantity unevenness partially Can happen.

Further, even if a dot-shaped minute light-shielding portion having a size equal to or less than the limit resolution of the exposure apparatus is formed in accordance with a predetermined density distribution, the pitch of the minute light-shielding portion is different between a high-density region and a low-density region. The difference is large, and the difference between the diffracted light that can be captured by the illumination optical system and the diffracted light that cannot be captured occurs depending on the pitch of the minute light shielding portion. As a result, even if the dot-shaped minute light-shielding portion is formed according to a predetermined density distribution so that the transmittance changes linearly from 0% to 100%, the mask (hence, the light-shielding portion) The illuminance distribution formed on the photosensitive substrate) deviates from a linear distribution. In other words, even if a dot-shaped minute light-shielding portion having a size equal to or less than the limit resolution of the exposure device is formed according to a predetermined density distribution, if exposure is performed without moving the mask blind, a local region is exposed in the exposure region of the photosensitive substrate. The exposure light quantity unevenness occurs.

Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-135166, even if the foreign matter adhering to the mask blind is periodically inspected by a foreign matter inspection mechanism having a simple structure, the mask blind is not connected to the mask. If a minute foreign matter of a predetermined size or more adheres to the mask blind because it is located at a substantially conjugate position, the minute foreign matter is transferred onto the photosensitive substrate and causes a defect in a manufacturing device. Has not changed. Even if general consideration is given to dust generation, there is a high possibility that foreign substances of a harmful size that can be transferred onto the photosensitive substrate will adhere to some extent. Even so, it is impossible to avoid the attachment of foreign substances of harmful size. Therefore, in the exposure apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-135166, it is conceivable that a foreign substance having a harmful size is detected to some extent frequently in a periodic foreign substance inspection. When a foreign substance having a harmful size is detected, it is necessary to clean the mask blind each time, so that the operation rate of the exposure apparatus decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-mentioned problem, in which a pattern formed of minute light-shielding portions formed in a dimming region of a mask blind and foreign matter adhering to the mask blind are transferred to a photosensitive substrate. An object of the present invention is to provide an exposure apparatus and an exposure method configured so as not to cause exposure light amount unevenness.

[0010]

According to a first aspect of the present invention, there is provided an illumination optical system for illuminating a mask on which a pattern for transfer is formed with predetermined illumination light. Illumination area defining means for defining an illumination area of the mask disposed at a position substantially conjugate with the mask in the optical path of the illumination optical system, and a plurality of unit exposure areas partially overlapping on the photosensitive substrate. An exposure apparatus for sequentially exposing an image of the pattern of the mask, wherein the illumination area defining means illuminates each of the plurality of blind members with each of the plurality of blind members when exposing each of the plurality of unit exposure areas. A drive system for constantly moving along a predetermined direction across the optical axis of the optical system,
Each blind member, a light-transmitting region for transmitting the illumination light, a light-shielding region for blocking the transmission of the illumination light,
A light-reducing region formed between the light-transmitting region and the light-shielding region, and an exposure light amount between an overlapping exposure region partially overlapping the plurality of unit exposure regions and an exposure region other than the overlapping exposure region. Is provided so that the light-reducing area of each blind member has a predetermined transmittance distribution with respect to the illumination light.

According to a preferred aspect of the first invention, the illumination area defining means is arranged at a predetermined interval along an optical axis of the illumination optical system so as to sandwich a position conjugate with the mask. Having two blind members, wherein the driving system includes:
A first orthogonal to the optical axis of the illumination optical system by a predetermined distance corresponding to the width of the overlapping exposure area on the photosensitive substrate;
Each of the blind members is driven along a direction, in each of the blind members, the dimming region extends in a rectangular shape along the first direction, and a boundary between the light transmitting region and the light shielding region is formed by the illumination optical system. And extends along a second direction orthogonal to the first direction in a plane orthogonal to the optical axis of the first direction.

According to a second aspect of the present invention, when illuminating a mask on which a pattern for transfer is formed with predetermined illumination light, the mask is formed by a plurality of blind members arranged at positions substantially conjugate with the mask. An exposure method that defines an illumination area, and sequentially exposes an image of a pattern formed in the illumination area of the mask to a plurality of unit exposure areas that partially overlap on a photosensitive substrate, wherein each of the plurality of blind members is A light-transmitting region for transmitting the illumination light, and a light-blocking region for blocking the transmission of the illumination light,
An overlapping exposure area formed between the light-transmitting area and the light-shielding area, the light-irradiating area having a predetermined transmittance distribution with respect to the illumination light, and partially overlapping the plurality of unit exposure areas; And exposing each of the plurality of blind members along a predetermined direction crossing a reference optical axis so that the exposure light amounts substantially coincide with each other in an exposure region other than the overlapping exposure region. provide.

[0013]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a mask blind as illumination area defining means for defining an illumination area of a mask, which is arranged at a position substantially conjugate with the mask, has a plurality of blind members, for example, conjugate with the mask. It is composed of two blind members arranged at a predetermined interval so as to sandwich the position. In each of the pair of blind members,
A light-transmitting region for transmitting the exposure light (illumination light), a light-blocking region for blocking the transmission of the exposure light, and a dimming region having a predetermined transmittance distribution for the exposure light are formed. Then, when exposing each unit exposure region that partially overlaps on the photosensitive substrate, each blind member is always moved along a predetermined direction crossing the reference optical axis. as a result,
In the plurality of unit exposure regions on the photosensitive substrate, a desired exposure light amount distribution can be obtained in which the exposure light amounts are substantially the same in the overlapping exposure region partially overlapping with the other exposure regions.

According to a more specific embodiment, the dimming region extends in a rectangular shape along the moving direction of each blind member, and an edge pattern formed by a boundary between the light transmitting region and the light shielding region is orthogonal to the moving direction. Extending along the direction. here,
In an arbitrary dimming region having a width corresponding to the moving distance of each blind member, the integrated transmittance integrated along the moving direction is substantially linear from the light transmitting region side to the light shielding region along a direction orthogonal to the moving direction. Is decreasing. Each of the blind members moves on the photosensitive substrate at a substantially constant speed in different directions from each other by a predetermined distance corresponding to the width of the overlapped exposure area. As a result, exposure to the overlapping exposure region is performed by light that has passed through the dimming region of the blind member and the pattern region of the mask, and a desired exposure light amount distribution that linearly changes, for example, is obtained in the overlapping exposure region.

By the way, in the prior art, since the mask blind does not move during the exposure, the size of the minute light-shielding portion is adjusted so that the dot-like minute light-shielding portion formed in the dimming area is not transferred onto the photosensitive substrate. It was necessary to make it smaller than the limit resolution of the device. In contrast, in the present invention,
Since the mask blind moves during the exposure, it is only necessary that the integrated transmittance with respect to the movement width in the dimming region shows a predetermined distribution, and the size of the dot-shaped minute light shielding portion to be formed in the dimming region is determined by the exposure device. It is not necessary to make the resolution smaller than. In other words, a large number of minute light-shielding portions having a size easy to draw and having a size sufficiently small with respect to the moving width of each blind member are formed along a predetermined density distribution without depending on various conditions of the exposure apparatus. Thereby, a pattern that is not transferred onto the photosensitive substrate can be easily formed in the darkened area.

Further, in the prior art, since the mask blind does not move during the exposure, even if a considerably small foreign substance adheres to the blind member, a large amount of exposure light unevenness occurs on the photosensitive substrate. On the other hand, in the present invention, since the mask blind moves during the exposure, even if a considerably large foreign substance adheres to the blind member, as will be specifically verified in the examples described later, the photosensitive substrate is exposed on the photosensitive substrate. In this case, unevenness in the exposure light amount can be suppressed. In other words,
In the exposure apparatus of the present invention, if ordinary consideration is given to dust generation, it is possible to sufficiently prevent foreign substances having a harmful size from adhering to the blind member, and as a result, exposure on the photosensitive substrate due to the influence of the foreign substances is possible. Irregularity of light quantity can be suppressed sufficiently small.

As described above, in the exposure apparatus according to the present invention, the pattern formed by the minute light-shielding portion formed in the dark area of the mask blind and the foreign matter adhering to the mask blind are transferred to the photosensitive substrate and the unevenness of the exposure light amount is reduced. A configuration that is unlikely to cause a problem can be realized. As a result, according to the present invention, it is possible to manufacture a good device having no defect at a pattern seam in a large-area pattern formed by screen synthesis on a photosensitive substrate.

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a view schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In the present embodiment, the present invention is applied to a projection exposure apparatus used for manufacturing a liquid crystal display element. In FIG. 1, Z is parallel to the optical axis AX of the projection optical system 14.
An X-axis is set in a plane perpendicular to the optical axis AX, and an X-axis is set in a plane perpendicular to the optical axis AX, and a Y-axis is set in a plane perpendicular to the optical axis AX, perpendicular to the plane of FIG.

The projection exposure apparatus shown in FIG. 1 includes a light source 1 composed of, for example, an ultra-high pressure mercury lamp. Light source 1
It is positioned at the first focal position of the elliptical mirror 2 having a reflection surface composed of a spheroid. Therefore, the illumination light flux emitted from the light source 1 forms a light source image at the second focal position P1 of the elliptical mirror 2 via the mirror 3. A light beam from the light source image formed at the second focal position P1 of the elliptical mirror 2 is converted into a substantially parallel light beam by the collector lens 4, and then a wavelength selection filter 5 that transmits only a light beam in a desired wavelength range.
Incident on. Light (for example, g-line (436 nm) or i-line (365 nm)) having the exposure wavelength selected through the wavelength selection filter 5 enters the fly-eye integrator 6.

The fly-eye integrator 6 is constituted by arranging a large number of positive lens elements vertically and horizontally such that the central axis thereof extends along the optical axis AX. Therefore, the luminous flux incident on the fly-eye integrator 6 is split into wavefronts by a large number of lens elements, and the rear focal plane of the fly-eye integrator 6 (that is, in the vicinity of the exit surface) is composed of the same number of light source images as the number of lens elements. The next light source is formed. That is, a substantial surface light source is formed on the rear focal plane of the fly-eye integrator 6.

A light beam from the secondary light source is restricted by an aperture stop 7 arranged near the rear focal plane of the fly-eye integrator 6 and then enters the first relay lens 8. The aperture stop 7 is disposed at a position optically substantially conjugate with an entrance pupil plane of the projection optical system 14 described later, and has a variable aperture for defining a range of a secondary light source contributing to illumination. The aperture stop 7 changes the aperture diameter of the variable aperture to change the σ value (the ratio of the aperture of the light source image on the pupil plane to the aperture diameter of the pupil plane of the projection optical system) that determines the illumination condition. Set to the desired value.

The light beam condensed via the first relay lens 8 is incident on a mask blind 9 disposed at a position optically substantially conjugate with the mask 13 in order to define an illumination area of the mask 13 described later. . The configuration and operation of the mask blind 9 as the illumination area defining means will be described later. The light beam passing through the mask blind 9 is superimposedly illuminating a mask 13 on which a predetermined transfer pattern is formed, via a blind relay system (10, 11) and a bending mirror 12 arranged in the optical path of the blind relay system. I do.

The light beam transmitted through the mask 13 reaches a plate 15 as a photosensitive substrate via a projection optical system 14. Thus, a pattern image of the mask 13 is formed in the unit exposure area on the plate 15. Here, since the aperture stop 7 and the entrance pupil plane of the projection optical system 14 are arranged almost conjugate as described above, an image of the secondary light source is formed on the entrance pupil plane of the projection optical system 14 and the mask 13 and the plate 15 are so-called Koehler-illuminated.

The plate 15 is supported on a plate stage 16 which can move two-dimensionally in a plane (XY plane) perpendicular to the optical axis AX of the projection optical system 14. Therefore, by sequentially performing exposure while moving the plate stage 16 and thus the plate 15 two-dimensionally, the pattern of the mask 13 can be sequentially transferred to each unit exposure area of the plate 15.

FIG. 2 is an enlarged perspective view showing a main part of the mask blind 9 shown in FIG. 1 and shows a pair of blind members constituting the mask blind 9 from the light source side along the optical axis AX. is there. As shown in FIG. 2, the mask blind 9 includes blind members 21 and 22 formed of a transparent glass substrate formed in a plate shape parallel to the YZ plane.
It has. A pair of blind members 21 and 22
Are arranged at equal intervals along the optical axis AX about the intersection P2 between the optical axis AX and a plane conjugate to the pattern surface of the mask 13.

Light blocking areas 21a and 22a and dimming areas 21b and 22b are formed on opposing surfaces of the blind members 21 and 22, respectively. Here, the light-shielding regions 21a and 22a allow the transmission of the exposure light to be almost 100%.
%, And the dimming regions 21b and 22b are regions having a predetermined transmittance distribution for the exposure light as described later. Therefore, the blind members 21 and 22
In the area where neither the light-shielding area nor the dimming area is formed (the white area in FIG. 2), the exposure light is almost 1%.
Light-transmitting regions 21c and 22c that transmit 00% of light are formed.

In the blind member 21, the light transmitting area 21c
Are formed in a rectangular shape along the Y direction and the Z direction, and the light-shielding region 21a is composed of a rectangular portion extending along the Z direction and a rectangular portion extending along the Y direction, and has an overall L-shape. Is formed. Note that the light-shielding region 21a is
1c is formed on the −Z direction side and the −Y direction side.
A rectangular dimming region 21b extending along the Y direction is formed between the light transmitting region 21c and the rectangular portion of the light shielding region 21a along the Y direction. The boundary between the light-transmitting region 21c and the rectangular portion of the light-shielding region 21a along the Z direction forms an edge pattern 21d along the Z direction. On the other hand, the blind member 22 has basically the same configuration as the blind member 21,
a is formed on the + Z direction side and the + Y direction side of the light transmitting region 22c.

FIG. 3 is a diagram showing the configuration of the light-reducing region of the blind member, and is an enlarged view of the light-reducing region 21b of the blind member 21 on the light source side as viewed from the mask side along the optical axis AX. As shown in FIG. 3, in the dimming area 21 b of the blind member 21, dot-shaped minute light-shielding portions are formed according to a predetermined density distribution. More specifically, FIG.
, A region indicated by a rectangular range 31 forms one unit dimming region, and the pattern of the unit dimming region 31 is repeated at the same pitch (width of the unit dimming region 31) along the Y direction. .

In the unit dimming region 31, the formation density of the dot-shaped minute light shielding portions increases from the light transmitting region 21c toward the light shielding region 21a, that is, along the -Z direction. In other words, in the unit dimming region 31, the transmittance for the exposure light decreases along the -Z direction. More specifically, the integrated transmittance integrated in the Y direction in the unit dimming region 31 linearly decreases from 100% to 0% along the -Z direction from the light transmitting region 21c to the light shielding region 21a. Here, each minute light-shielding portion is formed of a light-shielding thin film such as chromium, and may be rectangular (square or rectangular) or circular. The dimming region 22b of the other blind member 22 is also the blind member 2
It is formed in the same manner as the first dimming region 21b.

Here, referring again to FIG. 1, the mask blind 9 includes a drive system 23 for moving the light source side blind member 21 in the Y direction, and a mask side blind member 22 in the Y direction. And a drive system 24 for moving it. As described above, in order to mechanically drive the pair of blind members 21 and 22, respectively, the distance between the pair of blind members 21 and 22 is several hundred μm.
m intervals are ensured.

FIG. 4 shows four unit exposure areas EA1 on the plate 15 when four patterns are synthesized on a screen.
It is a figure which shows arrangement | positioning of -EA4, and the overlap. FIG. 5 is a view for explaining the operation of the mask blind 9 when exposing the first unit exposure area EA1 on the plate 15 and shows the mask blind 9 from the light source side along the optical axis AX. It is. Further, FIG.
It is a top view which shows the structure of 3 pattern surfaces.

As shown in FIG. 6, on the pattern surface of the mask 13, a rectangular pattern area 61 on which a transfer pattern is drawn and a light-shielding band 62 surrounding the rectangular pattern area 61 are formed. Have been. For example, a chromium film is vapor-deposited on the light-shielding band 62 so as to block almost 100% of transmission of exposure light. Thus, a rectangular light-shielding band edge 63 is formed between the pattern region 61 and the light-shielding band 62. Hereinafter, each exposure operation performed in the order of the first unit exposure area EA1, the second unit exposure area EA2, the third unit exposure area EA3, and the fourth unit exposure area EA4 will be described with reference to FIGS.

First, in the exposure of the first unit exposure area EA1, the pair of blind members 21 and 22 are initially positioned with respect to the mask 13 according to the positional relationship shown in FIG. That is, in the initial state, the dimming area 21b and the edge pattern 21d of the blind member 21 are set.
Overlaps with the pattern region 61 (not shown in FIG. 5) of the mask 13, and the dimming region 22 b and the edge pattern 22 d of the blind member 22 overlap with the light-shielding band 62 (not shown in FIG. 5) of the mask 13. In the exposure to the first unit exposure area EA1, the blind member 21 is moved by the drive system 23 in the -Y direction and the blind member 22 is moved by the drive system 24 in the + Y direction at a constant speed from the initial state shown by the solid line in FIG. Let it. The blind member 21 associated with the exposure
And the moving distance of the blind member 21 (22)
N times the width (length in the Y direction) of the unit dimming region 31 of the dimming region 21b (21b) (where N is a positive integer: N = N in FIG. 3)
2). Thus, the first unit exposure area EA1 on the plate 15 which is a photosensitive substrate is exposed.

FIG. 7 is a diagram showing an exposure state of the first unit exposure area EA1 on the plate 15. The first shown in FIG.
In the unit exposure area EA1, an area 71 is an area exposed by light having passed through the dimming area 21b of the blind member 21, and an area 72 is defined by a passing area of the edge pattern 21d of the blind member 21 during exposure. An exposure area, and an area 73 other than the area 71 and the area 72
Is an area exposed by light passing through the translucent area 21c of the blind member 21. Here, it goes without saying that, out of the four boundary lines defining the region 73, the boundary lines 73 a and 73 b not in contact with the region 71 and the region 72 are defined by the light-shielding band edge 63 of the mask 13.

Accordingly, lines 74 and 7 in FIG.
As shown by 5, the exposure light amount in the exposure area 73 is constant. Further, the amount of exposure light in the exposure region 72 linearly decreases from the boundary with the exposure region 73 toward the outer edge because the edge pattern 21d moves at a constant speed.
Further, the amount of exposure light in the exposure region 71 is also reduced.
1b is an integral multiple of the width of the unit dimming area 31 (in this case, 2
), And linearly decreases from the boundary with the exposure area 73 toward the outer edge. This is the unit dimming area 3
This is because since the integrated transmittance at 1 changes linearly, the integrated exposure light amount of the exposure area 71 during the movement of an integral multiple of the width of the unit dimming area 31 also changes linearly.

Next, after moving the plate stage 16 and thus the plate 15, the second unit exposure area EA
Exposure to 2 is performed. In the initial state of the exposure to the second unit exposure area EA2, the dimming area 21b of the blind member 21 and the edge pattern 22d of the blind member 22 overlap the pattern area 61 of the mask 13, and the blind member 2
The second darkening region 22 b and the edge pattern 21 d of the blind member 21 overlap the light-shielding band 62 of the mask 13. Then, the blind member 21 is driven by the drive system 23 to −
In the Y direction, the blind member 22 is moved + Y by the drive system 24.
Move at a constant speed in the direction. The moving distance of the blind members 21 and 22 during the exposure is the same as the exposure of the first unit exposure area EA1.

Further, after moving the plate 15, the third unit exposure area EA3 is exposed. In the initial state of exposure to the third unit exposure area EA3, the blind member 22
The darkening region 22b and the edge pattern 22d overlap with the pattern region 61 of the mask 13, and the blind member 21
The light-reducing region 21b and the edge pattern 21d overlap the light-shielding band 62 of the mask 13. And the drive system 23
To move the blind member 21 in the -Y direction and the drive system 24 to move the blind member 22 in the + Y direction at a constant speed. The blind members 21 and 2 associated with the exposure
The movement distance of No. 2 is the same as the exposure of the first unit exposure area EA1 and the second unit exposure area EA2.

Finally, after the plate 15 is further moved, the fourth unit exposure area EA4 is exposed. In the initial state of the exposure to the fourth unit exposure area EA4, the dimming area 22b of the blind member 22 and the edge pattern 21d of the blind member 21 overlap the pattern area 61 of the mask 13, and the dimming area 21b of the blind member 21 and the blind. The edge pattern 22d of the member 22 is
Overlap with the light-shielding band 62 of FIG. Then, the blind member 21 is moved at a constant speed in the −Y direction by the drive system 23 and the blind member 22 is moved in the + Y direction by the drive system 24. The moving distance of the blind members 21 and 22 during the exposure is the same as the exposure of the first unit exposure area EA1 to the third unit exposure area EA3.

In this manner, by sequentially performing exposure while moving the plate 15 two-dimensionally, a substantially constant exposure light amount can be obtained in the four unit exposure areas EA1 to EA4 on the plate 15. That is, it is possible to obtain an exposure light amount that is substantially the same in the overlapping exposure regions (regions indicated by oblique lines in FIG. 4) 41 to 44 and the other exposure regions (regions indicated by white in FIG. 4).

In the above embodiment, four exposures are performed in the area 45 where the four overlapping exposure areas 41 to 44 in FIG. 4 overlap. Hereinafter, the exposure light amount distribution of the four overlapping exposure regions 45 will be discussed. When the width of the unit dimming area of the dimming area of each blind member is set to の of the exposure movement amount of each blind member, the first exposure (that is, exposure to the first unit exposure area EA1) Accordingly, a desired exposure light quantity distribution can be obtained in the right half area of the four overlapping exposure areas 45 in the figure, but an error occurs in the exposure light quantity distribution in the left half area of the four overlapping exposure areas 45 in the figure. .

Similarly, in the second exposure (ie, exposure to the second unit exposure area EA2), the four overlapping exposure areas 45
A desired exposure light amount distribution can be obtained in the left half region in the drawing, but an error occurs in the exposure light distribution in the right half region in the four overlapping exposure region 45 in the drawing. Also, the third exposure (that is, exposure to the third unit exposure area EA3)
Thus, a desired exposure light amount distribution can be obtained in the left half area of the four overlapping exposure area 45 in the figure, but an error occurs in the exposure light distribution in the right half area of the four overlapping exposure area 45 in the figure. . Further, in the fourth exposure (that is, exposure to the fourth unit exposure area EA4), the four overlapping exposure areas 45
A desired exposure light amount distribution can be obtained in the right half area in the drawing, but an error occurs in the exposure light distribution in the left half area in the four overlapping exposure area 45 in the drawing. Thus, 4
As a result of repeating the exposure over four times, four overlapping exposure areas 45
In this case, a certain error occurs in the exposure light amount distribution.

In order to reduce the error of the exposure light quantity distribution in the four overlapping exposure areas 45, the width of the unit dimming area of the dimming area of each blind member is set to 1 / N of the exposure moving distance of each blind member. May be set as large as possible. For example, if the width of the unit dimming area of the dimming area of each blind member is set to 1/10 (N = 10) of the exposure movement amount of each blind member, 4 ×
A desired exposure light amount distribution can be obtained in an area of 90% of the overlapping exposure area 45, and an area where an error occurs is 10% of the four overlapping exposure area 45. Even if an error of about 10% occurs in the error area of 10%, an error of about 1% is obtained for the entire exposure light quantity of the entire 4-overlap exposure area 45, and a sufficiently good exposure light quantity distribution is obtained. Can be.

In the prior art, since the mask blind does not move during the exposure, it is necessary to make the size of the dot-shaped minute light-shielding portion formed in the dimming area smaller than the limit resolution of the exposure apparatus. Specifically, the magnification of the projection optical system is set to 1: 1, the NA of the projection optical system is set to 0.1, the magnification of the blind relay system is set to 4 times, and the NA of the illumination optical system for illuminating the mask is set to 0.05. If set, the illumination NA on the mask blind is 0.2. That is, assuming that the exposure wavelength is g-line (wavelength λ = 436 nm), the critical size R that can be transferred onto the plate of the minute light-shielding portion on the dimming region of each blind member of the mask blind is expressed by the following equation. It is represented by (1). R = λ / 2NA = 436 × 10 ⁻³ /(2×0.2)≒1 μm (1)

That is, in order to prevent the minute light-shielding portions on the light-reducing region of each blind member from being transferred onto the plate, a large number of dot-like minute light-shielding portions smaller than 1 μm are formed along a predetermined density distribution. There is a need to. In other words, unless a special device such as an electron beam drawing machine is used, it is impossible to form a special fine pattern including such small dot-shaped minute light shielding portions. Further, when the projection optical system is a magnifying optical system (magnification is larger than 1) or the exposure wavelength is an i-line (365 nm) having a shorter wavelength than the g-line, a dot smaller than 1 μm is used. It is necessary to form a large number of minute light-shielding portions along a predetermined density distribution. As a result, the drawing accuracy becomes too strict, and it becomes difficult to form a pattern composed of dot-shaped minute light-shielding portions in the dimming region.

On the other hand, in the present embodiment, since each of the blind members (21, 22) of the mask blind 9 moves during the exposure, the dot-shaped minute light-shielding portion to be formed in the dimming region of each of the blind members is used. Does not need to be smaller than the limit resolution of the exposure apparatus. That is, a dot-shaped minute light-shielding portion having a size that allows easy drawing and a size that is sufficiently small (for example, about 2 μm to 5 μm) with respect to the movement width of each blind member without depending on various conditions of the exposure apparatus is provided. By forming a large number in accordance with the density distribution, a pattern that is not transferred onto the plate can be easily formed in the dimming region.

FIG. 8 is a view for explaining the relationship between the foreign matter adhered on each blind member and the exposure light amount unevenness on the plate in this embodiment. In FIG. 8, mask 1
2 and the conjugate plane with the plate 15 (point P2 in FIG. 2)
And a surface of the blind member (a surface facing a pair of blind members) 82 is arranged at a distance d from the surface 81 perpendicular to the optical axis AX) along the optical axis AX. In this case, the relationship expressed by the following equation (2) approximately holds between the radius r of the foreign matter 83 assumed to be circular or spherical and the allowable value Pp of the exposure light amount unevenness. (Π × r ² × 2 × r) / (π × (d × NA) ² × L) = Pp (2)

Here, NA is the illumination NA on the mask blind 9, and L is the amount of movement of each blind member during exposure. Therefore, the illumination NA on the mask blind 9 is set to 0.2, and the conjugate plane 81 and the blind plane 8 are set.
2, the distance d between each blind member is 300 μm, the moving amount L of each blind member is 1.5 mm, and the allowable value of the exposure light amount unevenness Pp =
If it is 0.03 (ie, 3%), the allowable size (diameter) 2r of the foreign matter is about 85 μm. In other words,
By preventing foreign matter larger than about 85 μm from adhering to the blind member, the exposure light amount unevenness on the plate can be reduced by 3%.
Can be suppressed. If ordinary consideration is given to dust generation in the exposure apparatus, it is possible to sufficiently prevent foreign matter having a size larger than about 85 μm from adhering to the blind member. Therefore, in the exposure apparatus of the present embodiment, it is possible to sufficiently suppress the exposure light amount unevenness on the photosensitive substrate due to the influence of the adhesion of the foreign matter to the blind member.

In the prior art in which the mask blind does not move during the exposure, the relationship shown in the following equation (3) is approximately established between the radius r of the foreign matter and the allowable value Pp of the exposure light amount unevenness. (Π × r ² ) / (π × (d × NA) ² ) = Pp (3) Therefore, similarly to the above numerical example, the illumination NA on the mask blind is set to 0.2, and the conjugate plane and the blind plane are set. And the tolerance d = 300 μm, and the allowable value Pp of the exposure light amount unevenness.
If 0.03 (that is, 3%), the allowable size (diameter) of the foreign matter is about 20 μm. In other words, in the related art in which the mask blind does not move during the exposure, if a foreign matter larger than about 20 μm adheres to the blind member, the exposure light amount unevenness on the plate becomes larger than 3%. As described above, it is impossible to prevent foreign matters having a size of about 20 μm from adhering to the blind member even if the airtightness is increased or a treatment such as suction is performed. Thus, it can be seen that in the conventional exposure apparatus, a certain amount of exposure light amount unevenness has occurred on the photosensitive substrate due to the effect of the adhesion of the foreign matter to the blind member.

As described above, in the exposure apparatus of this embodiment,
The pattern consisting of the minute light-shielding portions formed in the darkened area of each blind member of the mask blind is unlikely to cause transfer to the photosensitive substrate and uneven exposure light amount, and foreign matter attached to the mask blind is transferred to the photosensitive substrate. In addition, it is possible to realize a configuration that hardly causes unevenness in the exposure light amount. As a result, in this embodiment, it is possible to manufacture a good device having no defect at the pattern seam in a large-area pattern formed by screen synthesis on a photosensitive substrate.

FIG. 9 is a view showing a state in which triangular minute light-shielding portions are formed at a predetermined pitch in the light-reducing region as a first modification of the blind member. In FIG. 9, a triangular minute light-shielding portion having a base extending along the boundary between the light-shielding region and the light-reducing region and a vertex on the boundary between the light-transmitting region and the light-reducing region (shown by hatching in the figure) ) Are formed at a predetermined pitch along the moving direction of the blind member. The pitch at which the triangular minute light shielding portions are formed is set to 1 / N (N is a sufficiently large positive integer) of the exposure movement amount of the blind member. For example, in an exposure apparatus in which the magnification of the blind relay system is 4 × and the magnification of the projection optical system is 1 ×, if the width of the overlapping exposure area on the plate is 8 mm, the exposure movement amount of the blind member is 2 mm. is there. Therefore, N = 10
If it is set to 0, the formation pitch of the triangular minute light shielding portions is 20 μm.

As described above, in the case of the first modified example of FIG. 9, the width of the unit dimming region of the dimming region is 20 μm, and the integrated transmittance in this unit dimming region is from the light-transmitting region side to the light-shielding region side. It decreases linearly from 100% to 0%.
Therefore, when the dimming region is moved by 2 mm in the pitch direction of the minute light shielding portion, a desired linear exposure light amount distribution can be obtained in the exposure region formed on the plate via the dimming region. In addition, since each of the blind members moves during the exposure, a minute light shielding portion having a width of about 20 μm in the moving direction is not transferred onto the plate. However, in the first modified example of FIG. 9, since the base length of each minute light-shielding portion is 20 μm and its height is 2 mm (2000 μm), the apex angle of each minute light-shielding portion becomes an extremely small acute angle. turn into. As a result, in particular, the apex portion of each minute light shielding portion is easily peeled off, and for example, patterning by etching is difficult.

FIG. 10 is a view showing a state in which one shaded portion of a triangular minute light-shielding portion is formed in a staircase as a second modification of the blind member in which the patterning of the dimming region is easy. In the second modified example of FIG. 10, similarly to the first modified example of FIG. 9, the base extending along the boundary between the light-shielding region and the dimming region, and on the boundary between the light-transmitting region and the dimming region or Triangle-shaped minute light-shielding portions (shown by oblique lines in the figure) having vertices located in the vicinity thereof are formed at a predetermined pitch along the moving direction of the blind member. The pitch at which the triangular minute light shielding portions are formed is set to 1/100 of the exposure movement amount of the blind member. However, the oblique side on the left side in the figure of each minute light-shielding portion extends linearly in the vertical direction in the figure, but the oblique side on the right side in the figure is formed in a 10-step shape.

That is, focusing on the overall shape of the leftmost minute light-shielding portion 101 in FIG. 10 based on the same overall settings as in the first modification of FIG. 9, the base has a length of 20 μm.
The height is 2000 μm. The width of the uppermost first-stage light-shielding portion in the drawing is 2 μm and its height is 200 μm.
The width of the second-stage light-shielding portion is 4 μm and its height is 200 μm. Similarly, the width of the n-th light-shielding portion is (2 × n) μm and its height is 200 μm. . Next, the second minute light shielding portion 102 from the left in FIG.
Paying attention to this, the minute light shielding portion 102 is
1 is 40 μm (that is, the height of the light shielding portion of each stage is 200 μm).
It can be seen that the shape is displaced in the vertical direction in the figure by １ ／ of m). Similarly, the third minute light shielding portion 103 from the left in FIG.
(That is, 2/5 of the height of the light-shielding portion of each step is 200 μm)
Only the shape is shifted in the vertical direction in the figure. In addition, the fourth minute light-shielding portion 104 from the left side in FIG. 10 has a shape in which the minute light-shielding portion 101 is displaced in the vertical direction in the drawing by 120 μm (that is, ／ of the height of the light-shielding portion of each step is 200 μm). The fifth minute light shielding portion 1 from the left in FIG.
Reference numeral 05 denotes a shape in which the minute light-shielding portion 101 is displaced in the vertical direction in the figure by 160 μm (that is, 4/5 of the height of the light-shielding portion of each step is 200 μm).

Thus, for example, considering the integrated transmittance of only the 20 μm-wide dimming region including the minute light-shielding portion 101, it changes stepwise in steps of 10% from 100% to 0%. Considering the integrated transmittance of the unit darkening region 106 having a width of 100 μm including 105, it can be seen that it changes stepwise by 2%. That is, the integrated transmittance of the unit dimming region 106 changes almost linearly,
In an exposure region formed on a plate via such a dimming region in which the unit dimming regions are repeatedly formed at a predetermined pitch, a substantially linear exposure light amount distribution can be obtained.
Further, in order to improve the linearity of the integrated transmittance in the unit dimming region, that is, the linearity of the exposure light amount distribution, the adjacent minute light-shielding portions in FIG. The unit light-extinguishing area may be formed by ten consecutive minute light-shielding portions, and the unit light-extinguishing area may be repeatedly patterned at a predetermined pitch. In FIG. 10, the positions of the minute light-shielding portions are shifted stepwise (regularly). However, the position shifts of the minute light-shielding portions may be randomly arranged in the scan width (that is, the unit dimming region). That is natural.

FIG. 11 shows a third modification of the blind member in which bar-shaped minute light-shielding portions of various lengths are formed at predetermined pitches in the light-reducing region to form the unit light-reducing region in a bar graph shape. FIG. In the third modified example of FIG. 11, bar-shaped minute light-shielding portions having different lengths are formed at a predetermined pitch in the unit dimming region. More specifically, assuming that an intermediate portion where no minute light-shielding portion is actually formed is a minute light-shielding portion having a length of 0, a total of ten minute light-shielding portions are formed in the unit dimming region. I have. The leftmost minute light-shielding portion in the drawing has a height of about 11% of the entire height of the dimming region (the length of the dimming region in the vertical direction in the drawing). Hereinafter, the second minute light shielding portion from the left is about 44
%, The third minute light shield is about 77%, the fourth minute light shield is about 22%, the fifth minute light shield is 100%, the sixth minute light shield is 0%, and the seventh minute light shield is Is about 66%,
The eighth minute light shield has a height of about 88%, the ninth minute light shield has a height of about 55%, and the tenth minute light shield has a height of about 33%.

Thus, considering the integrated transmittance in the unit dimming region, it can be seen that it changes stepwise from 100% to 0% in steps of about 11%. That is, the integrated transmittance of the unit dimming region according to the third modified example of FIG. 11 changes almost linearly, and the unit dimming region passes through the dimming region repeatedly formed at a predetermined pitch. In the exposure area formed on the plate, a substantially linear exposure light amount distribution can be obtained. Further, in order to improve the linearity of the integrated transmittance of the unit dimming region, that is, the linearity of the exposure light amount distribution, the number of rod-shaped minute light shielding portions constituting the unit dimming region in FIG. 11 may be increased.

In the blind member according to the embodiment shown in FIG. 3, the unit light reduction area is formed by forming dot-shaped minute light-shielding portions at random, but the dot-shaped minute light-shielding portions are regularly arranged. By forming them, a unit dimming area can be formed. When the unit light-reducing region is formed by the dot-shaped minute light-shielding portions, as shown in FIG. 12, the number of minute light-shielding portions formed every three stages from the light-transmitting region side may be increased by one. . More generally, the number of minute light shielding portions formed every n (n is a positive integer) stages from the light transmitting region side may be increased by m (m is a positive integer).

In the above-described embodiment and each of the modifications,
Although the integrated transmittance of the unit dimming region is linearly changed, the integrated transmittance can be changed nonlinearly as long as the integrated transmittance of the unit dimming region is complementary with a pair of blind members. . Further, in the above embodiment, the present invention is applied to an exposure apparatus for manufacturing a liquid crystal display element, but the present invention can also be applied to an exposure apparatus for manufacturing a semiconductor element. Further, in the above-described embodiment, the present invention is applied to the projection exposure apparatus that performs exposure via the projection optical system. However, other exposure apparatuses and other exposure apparatuses that perform exposure by bringing the mask and the photosensitive substrate close to each other are used. The present invention can be applied to a general exposure apparatus.

[0059]

As described above, according to the exposure apparatus of the present invention, the pattern formed of the minute light shielding portion formed in the darkened area of the mask blind and the foreign matter adhering to the mask blind are transferred to the photosensitive substrate. In addition, it is possible to realize a configuration that hardly causes unevenness in the exposure light amount. As a result, according to the present invention, it is possible to manufacture a good device having no defect at a pattern seam in a large-area pattern formed by screen synthesis on a photosensitive substrate.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a configuration of a main part of the mask blind 9 of FIG. 1 and is a view of a pair of blind members constituting the mask blind 9 from a light source side along an optical axis AX.

FIG. 3 is a diagram showing a configuration of a dimming region of the blind member, and is an enlarged view of a dimming region 21b of the blind member 21 on the light source side as viewed from the mask side along the optical axis AX.

FIG. 4 is a diagram showing the arrangement of four unit exposure areas EA1 to EA4 on a plate 15 and the overlapping of the four unit exposure areas when combining four patterns on a screen.

FIG. 5 is a view for explaining the operation of the mask blind 9 when exposing the first unit exposure area EA1 on the plate 15, and shows the mask blind 9 from the light source side along the optical axis AX.
FIG.

FIG. 6 is a plan view showing a configuration of a pattern surface of a mask 13;

FIG. 7 is a view showing an exposure state of a first unit exposure area EA1 on a plate 15;

FIG. 8 is a view for explaining the relationship between foreign matter adhering on each blind member and exposure light amount unevenness on a plate in this embodiment.

FIG. 9 is a view showing a state in which triangular minute light-shielding portions are formed at a predetermined pitch in a dimming region as a first modification of the blind member.

FIG. 10 is a diagram showing a state in which one oblique line portion of a triangular minute light-shielding portion is formed in a stepped shape as a second modification of the blind member in which the patterning of the dimming region is easy.

FIG. 11 is a diagram showing a state in which unit darkening regions are formed in a bar graph shape by forming bar-shaped minute light-shielding portions of various lengths at predetermined pitches in a darkening region as a third modification of the blind member. is there.

FIG. 12 is a diagram illustrating a state in which a unit dimming region is formed by increasing the number of dot-shaped minute light shielding portions by one for every three stages from the light transmitting region side.

[Explanation of symbols]

 Reference Signs List 1 light source 2 elliptical reflecting mirror 3 second focal point position 4 collector lens 5 wavelength selection filter 6 fly-eye integrator 7 aperture stop 8 first relay lens 9 mask blind 10, 11 blind relay system 12 mirror 13 mask 14 projection optical system 15 plate 16 Plate stage 21, 22 Blind member 23, 24 Drive system

Claims (8)

[Claims] An illumination optical system for illuminating a mask on which a transfer pattern is formed with predetermined illumination light, and the mask disposed at a position substantially conjugate with the mask in an optical path of the illumination optical system. An illumination area defining means for defining an illumination area, wherein the exposure area defining means sequentially exposes the image of the mask pattern to a plurality of unit exposure areas partially overlapping on a photosensitive substrate; A plurality of blind members, and a drive system for constantly moving each of the plurality of blind members along a predetermined direction across the optical axis of the illumination optical system upon exposure to each of the plurality of unit exposure regions. Having a light-transmitting region for transmitting the illumination light, and a light-shielding region for blocking the transmission of the illumination light.
A light-reducing region formed between the light-transmitting region and the light-shielding region; and an exposure light amount in an overlapping exposure region partially overlapping in the plurality of unit exposure regions and an exposure region other than the overlapping exposure region. An exposure apparatus characterized in that the darkened area of each blind member has a predetermined transmittance distribution with respect to the illumination light so as to approximately match. 2. The illumination area defining means includes two blind members arranged at a predetermined interval along an optical axis of the illumination optical system so as to sandwich a position conjugate with the mask. A drive system drives each blind member along a first direction orthogonal to an optical axis of the illumination optical system by a predetermined distance corresponding to a width of the overlapped exposure area on the photosensitive substrate. In each blind member, The dimming region extends in a rectangular shape along the first direction, and a boundary between the light transmitting region and the light shielding region is orthogonal to the first direction in a plane orthogonal to an optical axis of the illumination optical system. The exposure apparatus according to claim 1, wherein the exposure apparatus extends along a second direction. 3. In an arbitrary dimming area having a width corresponding to a moving distance of each blind member associated with exposure to each unit exposure area along the first direction, the integration is performed along the first direction. The exposure apparatus according to claim 2, wherein the integrated transmittance decreases substantially linearly from the light-transmitting region side to the light-shielding region side along the second direction. 4. The unit width of a region where the integrated transmittance along the first direction in the dimming region of each blind member decreases substantially linearly along the second direction is equal to the moving distance of each blind member. The exposure apparatus according to claim 3, wherein 1 / N (N is a positive integer) is set. 5. A light-shielding region according to claim 1, wherein a small light-shielding portion in a dot shape having a predetermined size is formed according to a predetermined density distribution. 3. The exposure apparatus according to claim 1. 6. A triangle having a base extending along a boundary between the light-shielding region and the light-reducing region and a vertex on a boundary between the light-transmitting region and the light-reducing region. The exposure apparatus according to any one of claims 1 to 4, wherein minute light-shielding portions having a shape are formed at a predetermined pitch along the first direction. 7. The exposure apparatus according to claim 6, wherein at least one oblique side portion of the triangular minute light shielding portion is formed in a step shape. 8. When illuminating a mask on which a pattern for transfer is formed with predetermined illumination light, an illumination region of the mask is defined by a plurality of blind members arranged at positions substantially conjugate with the mask. In an exposure method for sequentially exposing an image of a pattern formed in the illumination area of a mask to a plurality of unit exposure areas partially overlapping on a photosensitive substrate, each of the plurality of blind members transmits the illumination light. A light-blocking region for blocking the transmission of the illumination light, and a dimming formed between the light-transmitting region and the light-blocking region and having a predetermined transmittance distribution for the illumination light. The plurality of unit exposure areas so that the exposure light amounts in the overlapping exposure areas that partially overlap in the plurality of unit exposure areas and the exposure areas other than the overlapping exposure areas are substantially the same. Exposure method to and moving along a predetermined direction transverse to the reference optical axis of each of the Indian member.