KR102234255B1 - Exposure apparatus, and method of manufacturing article - Google Patents

Abstract

Even when the illuminance of the exposure light is high, a plurality of astigmatisms having different directions in the projection optical system are made to fall within the allowable range.
An exposure apparatus having a projection optical system that projects a pattern of a mask onto a substrate, and is disposed in the vicinity of the pupil plane or the pupil plane of the projection optical system and a first optical element whose position or shape can be changed to adjust the astigmatism of the projection optical system. A second optical element, a control unit for controlling the position or shape of the first optical element, and a supply unit for supplying a gas to the second optical element to adjust a temperature distribution of the second optical element, and the supply unit comprises: 2 The astigmatism in the first direction caused by the temperature distribution of the optical element and the direction of increase or decrease in the astigmatism in the second direction different from the first direction are opposite to each other, and the astigmatism in the first direction falls within the allowable range. Thus, the gas is supplied to the second optical element, and the position or shape of the first optical element is controlled so that the astigmatism in the second direction falls within the allowable range.

Description

Exposure apparatus and manufacturing method of article TECHNICAL FIELD {EXPOSURE APPARATUS, AND METHOD OF MANUFACTURING ARTICLE}

The present invention relates to an exposure apparatus and an article manufacturing method.

Exposure in which a mask (reticle) is illuminated by an illumination optical system in the manufacturing process of a semiconductor device or a liquid crystal display device, etc., and the image of the mask pattern is projected through a projection optical system on a substrate coated with a photosensitive resist layer. The device is being used.

The optical element of the projection optical system absorbs exposure light and generates a temperature distribution in the optical element, thereby changing the refractive index distribution and the surface shape of the optical element. From the viewpoint of imaging characteristics, it is desirable to reduce aberrations such as focus difference or astigmatism (AS) that may occur due to changes in the refractive index distribution or surface shape of the optical element.

Therefore, an exposure apparatus that reduces the change in temperature distribution in the projection optical system by supplying a temperature-controlled gas into the barrel containing the projection optical system in accordance with the temperature increase in the entire projection optical system caused by the member in the projection optical system absorbing the exposure light. Is known.

Japanese Patent Laid-Open No. 2016-95412 discloses that, when gas is supplied between the meniscus lens and the convex mirror installed in the vicinity of the pupil of the projection optical system, the meniscus is based on information on the pattern of the mask used for exposure. It is disclosed to control the temperature distribution of the lens and the direction of gas flow to match.

In Japanese Unexamined Patent Application Publication No. 2016-95412, since the lens is partially cooled by flowing gas in the region where the temperature of the lens has risen, when exposure light of high illuminance is incident on the projection optical system, the temperature distribution of the entire lens is It is assumed that it will not be sufficiently uniform. In that case, it is particularly difficult to make both the astigmatism in the vertical and horizontal direction of the projection optical system and the astigmatism in the oblique direction fall within the allowable range.

An exposure apparatus as an aspect of the present invention that solves the above problems is an exposure apparatus having a projection optical system that projects a pattern of a mask onto a substrate, and the projection optical system has a position or shape in order to adjust the astigmatism of the projection optical system. A changeable first optical element,

The projection optical system has a pupil plane or a second optical element disposed in the vicinity of the pupil plane, wherein the exposure apparatus includes a control unit for controlling a position or shape of the first optical element, and a temperature distribution of the second optical element Has a supply unit for supplying a gas to the second optical element in order to adjust, the supply unit includes astigmatism in a first direction and the first direction generated by a temperature distribution of the second optical element at the time of exposure A gas is supplied to the second optical element so that the direction of the increase or decrease of the astigmatism in the second direction different from that of is opposite to each other, and the astigmatism in the first direction falls within an allowable range, and the second optical element at the time of exposure. The position or shape of the first optical element is controlled so that the astigmatism in two directions falls within an allowable range.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

1 is a configuration diagram of an exposure apparatus.
Fig. 2 is a diagram showing a temperature distribution of a meniscus lens 15' after exposure.
Fig. 3 is a diagram showing a temperature distribution in terms of Zernike coefficients Z5 and Z6.
Fig. 4 is a diagram showing a configuration around a convex mirror 15 and a meniscus lens 15'.
5 is a cross-sectional view of the barrel 100.
6 is a diagram showing a temperature distribution after gas supply.
7 is a flowchart showing a method of correcting astigmatism.
Fig. 8 is a diagram showing a barrel, an air supply port, and an exhaust port according to the second embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

(First embodiment)

An exposure apparatus of this embodiment will be described with reference to FIG. 1. 1 is a schematic diagram of an exposure apparatus according to a first embodiment. The exposure apparatus can be used, for example, in a lithography process in a manufacturing process of a flat panel such as a liquid crystal display device or an organic EL device. In particular, in this embodiment, the exposure apparatus is a scanning type projection exposure apparatus that transfers (exposes) an image of a pattern formed on a mask onto a plate (on a substrate) by a step-and-scan method. In Fig. 1, the Y axis is taken in the scanning direction of the mask 9 and the plate 19 at the time of exposure in a plane perpendicular to the Z axis, which is the vertical direction, and the X axis is taken in the non-scanning direction orthogonal to the Y axis. The plate 19 is made of, for example, a glass material, and is a substrate to be processed on which a photosensitive agent (resist) is applied.

The exposure apparatus of the present embodiment includes an illumination system IL, a projection optical system PO, a disk drive mechanism for scanning a mask (original plate) 9 arranged on an object surface OP of the projection optical system PO, and an image surface IP of the projection optical system PO. A substrate driving mechanism for scanning the resulting substrate 19 and a control unit C are provided.

The illumination system IL is, for example, a light source LS, a first condensing lens 3, a fly-eye lens 4, a second condensing lens 5, a slit defining member 6, an imaging optical system 7, and a flat mirror 8 ) Can be included. The light source LS may include, for example, a mercury lamp 1 and an elliptical mirror 2. The slit defining member 6 defines the illumination range of the disk 9 (that is, the cross-sectional shape of the slit-shaped light illuminating the disk 9). The imaging optical system 7 is arranged so as to form a slit defined by the slit defining member 6 on an object surface. The planar mirror 8 bends the optical path in the illumination system IL. The projection optical system PO projects the pattern of the original plate 9 disposed on the object surface OP onto the substrate 19 disposed on the upper surface IP, thereby exposing the substrate 19. The projection optical system PO can be constituted by any of an equal-magnification imaging optical system, an enlarged imaging optical system, and a reduced imaging optical system. However, it is preferable that the projection optical system PO is configured as an equal-magnification imaging optical system, and the principal rays are parallel on the object surface side and the image surface side, that is, have both telecentricity on both the object surface and the image surface.

The projection optical system PO is a mirror arranged in order from the object surface side in the optical path from the object surface OP to the image surface IP, and is a first planar mirror 13, a first concave mirror 14, a convex mirror 15, and a second concave. It has a face mirror 16 and a second planar mirror 17. The optical path between the object OP and the first plane mirror 13 and the optical path between the second plane mirror 17 and the top surface IP are parallel. The plane including the mirror surface of the first plane mirror 13 and the plane including the mirror surface of the second plane mirror 17 form an angle of 90 degrees to each other. The first planar mirror 13 and the second planar mirror 17 may be formed integrally. The first concave mirror 14 and the second concave mirror 16 may be configured integrally. The projection optical system PO includes cylindrical lenses 21 and 22 arranged in an optical path between the object surface OP and the first planar mirror 13, and a plano-concave lens (or plano-convex lens) 12'. The projection optical system PO further includes cylindrical lenses 23 and 24 arranged in the optical path between the second planar mirror 17 and the image surface. In the projection optical system PO, a meniscus lens (aspherical lens) 15' is disposed in front of the convex mirror 15 in order to correct axial chromatic aberration caused by these lenses. The reflective surface of the convex mirror 15 corresponds to the pupil surface of the projection optical system. The convex mirror 15 is arranged on the pupil surface of the projection optical system, and the meniscus lens 15' is arranged in the vicinity of the pupil surface of the projection optical system. In these optical elements, uneven temperature distribution occurs during exposure.

The cylindrical lenses 23 and 24 project the projection optical system in a second direction (y direction) orthogonal to the first direction (z direction) along the optical path between the object surface OP and the first planar mirror 13 It comprises a 1st optical system which adjusts a magnification. These cylindrical lenses 21 and 22 constitute a second optical system that adjusts the projection magnification of the projection optical system in the first direction and in a third direction (x direction) orthogonal to the second direction. The plano-concave lens 12' constitutes a third optical system that adjusts the projection magnification of the projection optical system in the first direction and the second direction.

The cylindrical lens 21 is a concave cylindrical surface having a flat top surface and a curvature in the x direction on the bottom surface, and has an air gap of about 5 to 20 mm to the top surface of the cylindrical lens 22. Cylindrical lens 22 is a convex cylindrical surface having a curvature in the x-direction on an upper surface, a convex spherical surface on the lower surface, a concave spherical surface on the upper surface, and 5 to 20 to the upper surface of the plano-concave lens 12' having a flat surface on the lower surface. It has an air gap of about mm. The cylindrical lens 21 or the cylindrical lens 22 is configured to be movable (driveable) in the z direction by an actuator 31 (drive unit). With respect to the cylindrical lens 22, the magnification in the x direction is corrected by driving the cylindrical lens 21 in the z direction. Further, by driving the plano-concave lens 12' in the z direction by the actuator 31, the magnification is corrected isotropically in the x and y directions.

The control unit C is composed of, for example, a computer, and is connected to each component of the exposure apparatus through a line, and can control the operation and adjustment of each component according to a program or the like. The control unit C can control an actuator (driving unit) that drives a cylindrical lens or a plano-concave lens to control the position, shape, or both of the lens.

The cylindrical lens 23 has a concave cylindrical surface having a flat surface on an upper surface and a curvature in a scanning direction on a lower surface thereof, and an air gap of about 5 to 20 mm to the upper surface of the cylindrical lens 24. The cylindrical lens 24 has a convex cylindrical surface having a curvature in a scanning direction on an upper surface and a flat surface on a lower surface. The cylindrical lens 23 or the cylindrical lens 24 is configured such that its position can be changed (moved) in the z direction by the actuator 32. By moving the cylindrical lens 23 in the z direction by the actuator 32, the magnification in the y direction can be corrected. The thickness and spacing of each of the cylindrical lenses 21, 22, 23, 24 are within a range that does not cause weight deformation when held in a space, and a space holding mechanism and a vertical drive mechanism can be configured. Is random in In the case of synthetic quartz having a refractive index of around 1.475, the cylindrical surface changes the magnification by about 10 ppm with a movement of 1 mm when the radius of curvature is about 47000 mm. However, each of the cylindrical and spherical surfaces needs to be slightly changed so that the size of the image passing through the three sheets placed at the reference height position becomes exactly the same as when there were no three lenses. In addition, the concave surface and the convex surface of the cylindrical surface, and the concave surface and the convex surface of the spherical surface may be opposite to each other. Further, as the magnification correction means, not limited to the cylindrical lens, a mechanism that allows the position, shape, or both of the parallel plates to be changed, and a mechanism for bending the parallel plates, or a mechanism for adjusting the rotational position of the lens may be used. .

Further, if the cylindrical lens is moved as described above, the projection magnification can be adjusted, but the astigmatism can also be adjusted. For example, in the case of adjusting the projection magnification in the y direction, moving the cylindrical lens 23 having a concave cylindrical surface having a curvature in the scanning direction on the upper surface and a concave cylindrical surface on the lower surface in the z direction, is orthogonal to the scanning direction. Although the refractive power in the direction to be displayed does not change, negative refractive power is generated in the scanning direction. For this reason, a line image (V line) in the scanning direction is formed at a position (lower side) farther away from the projection optical system than a line image (H line) in the direction perpendicular to the scanning direction. That is, the first optical system has the sensitivity of the projection magnification in the y direction and the sensitivity of the astigmatism occurring in the vertical and horizontal directions (x, y directions). The second optical system has a sensitivity of a projection magnification in the x direction and a sensitivity of astigmatism occurring in a vertical and horizontal direction. The third optical system has the sensitivity of the projection magnification in the x direction and the y direction, and there is no sensitivity of the astigmatism occurring in the vertical and horizontal directions. Therefore, by driving these lenses, astigmatism in the vertical and horizontal directions can be generated without changing the projection magnification in two directions orthogonal to each other. As an example, when the cylindrical lens 21 is driven +1 mm in the Z direction, the cylindrical lens 23 is +2 mm in the Z direction, and the plano-concave lens 12' is driven +1 mm in the Z direction, Astigmatism in the vertical and horizontal directions can be generated by 3 µm without changing the projection magnification in the x and y directions. According to the above mechanism, the correction amount of astigmatism is proportional to the driving amount of the lens. Therefore, by setting a space for avoiding interference during driving between lenses, the amount of driving the lens can be increased, and the amount of astigmatism correction can be increased.

Therefore, the position of the lens (first optical element) of either of the cylindrical lenses 21, 22, 23, and 24 and the plano-concave lens 12' is controlled by the control unit C. Thereby, the projection magnification in the x- and y-directions can be set as a predetermined target value, and the astigmatism in the vertical and horizontal directions can be made within the allowable range. In addition, when a parallel flat plate is used instead of the cylindrical lens, the projection magnification and astigmatism can be adjusted by controlling the shape of the parallel flat plate.

Next, the temperature distribution of the meniscus lens 15' will be described. Fig. 2 shows the temperature distribution of the meniscus lens 15' when a certain mask pattern is exposed on the substrate. In addition, the temperature distribution of the convex mirror 15 is almost the same as that of the meniscus lens 15'. With the center of the meniscus lens 15' interposed therebetween, there is a high temperature area in both peripheral regions in the B-axis direction, and the peripheral regions on both sides in the C-axis direction with the center of the meniscus lens 15' interposed therebetween There is a low temperature section in the. 3 shows the terms Z5 and Z6 when the temperature distribution of the meniscus lens 15' is decomposed by the Zernike function.

The left drawing of FIG. 3 is a temperature distribution in the shape of a Z5 term of the Zernike coefficient, and the right drawing of FIG. 3 is a temperature distribution of the Z6 term of the Zernike coefficient. In the temperature distribution of the Z5 term of the Zernike coefficient, the center of the meniscus lens (15') is interposed, there are high-temperature regions near both ends in the X-axis direction, and the center of the meniscus lens (15') is Between them, there is a low temperature section near both ends in the Z-axis direction. In the temperature distribution of the Z6 term of the Zernike coefficient, the center of the meniscus lens (15') is interposed, there are high-temperature regions near both ends in the B-axis direction, and the center of the meniscus lens (15') is Between them, there is a low temperature section near both ends in the C-axis direction. In addition, the B axis and the C axis are axes inclined at an inclination of 45 degrees from the X axis or the Z axis, and are mutually perpendicular axes.

When the temperature distribution of the term Z5 occurs in the meniscus lens 15', it becomes the refractive index distribution of the term Z5, and wavefront aberration of the term Z5 occurs. When the wavefront aberration of term Z5 occurs, the focal position of the horizontal line (H-line) and the focal position of the vertical line (V-line) of the mask pattern are shifted. Accordingly, astigmatism in the vertical and horizontal direction, which is the difference between the focal position of the H-line and the focal position of the V-line, occurs. Further, when the temperature distribution of the term Z6 occurs in the meniscus lens 15', the distribution of the refractive index of the term Z6 becomes, and wavefront aberration of the term Z6 occurs. When the wavefront aberration of term Z6 occurs, the focal position of the upper right oblique line (S line) tilted 45 degrees with respect to the H line of the mask pattern and the focal position of the upper left oblique line (T line) tilted 135 deg with respect to the H line are shifted. Accordingly, astigmatism in the oblique direction, which is the difference between the focal position of the S-line and the focal position of the T-line, occurs. Here, the astigmatism in the oblique direction is referred to as the astigmatism in the first direction, and the astigmatism in the vertical and horizontal direction is referred to as the astigmatism in the second direction. In addition, the above-described vertical and horizontal direction and the inclined direction are 45 degrees different, but the angular difference between the first and second directions is not limited to 45 degrees, and may be different directions. In addition, the astigmatism in the oblique direction is not limited to the Z6 term, but may also include the Z13 term, and the astigmatism in the vertical and horizontal direction is not limited to the Z5 term, but may also include the Z12 term.

Next, temperature adjustment of the convex mirror 15 or the meniscus lens 15' (second optical element) will be described. Fig. 4 shows the configuration around the convex mirror 15 and the meniscus lens 15'. The right side view of FIG. 4 is a view seen from the Y direction, and the left side view of FIG. 4 shows a cross-sectional view at DD'. The dashed-dotted line in the Y-axis direction represents the optical axis. The convex mirror 15 and the meniscus lens 15' are held by the barrel 100 (retaining support). 4, between the convex mirror 15 and the meniscus lens 15', a closed space 102 is formed. A plurality of holes 103 and 104 extending in the Z direction are formed in the barrel 100. The hole 103 is a gas supply port, and the hole 104 is a gas exhaust port. 5 shows a cross-sectional view of the barrel 100 passing through AA′. In the barrel 100, a plurality of air supply ports 103A to 103G are formed as through holes. Each of the plurality of air supply ports 103A to 103G extends in the same Z direction. Further, in the barrel 100, with respect to the optical axis of the meniscus lens 15' at the intersection of the dashed-dotted line, the exhaust ports 104A to 104G are formed as through holes on the side opposite to the supply ports 103A to 103G. Is formed. Further, a supply port and an exhaust port extend in the barrel 100 in a direction from the supply port toward the exhaust port (Z direction). For example, the air supply port 103A extends in a direction parallel to the line passing through the optical axis of the air supply port 103D and the meniscus lens 15' (Z direction). On the lower side of the barrel 100, the plurality of air supply ports 103A to 103G are formed at substantially equal intervals in the X-axis direction. The plurality of exhaust ports 104A to 104G are formed at substantially equal intervals in the X-axis direction above the barrel 100. The plurality of supply ports 103A to 103G and the exhaust ports 104A to 104G are formed to a position covering the entire diameter of the convex mirror 15 and the meniscus lens 15' in the X direction. An air supply path 36 for supplying gas is connected to the plurality of air supply ports 103A to 103G, and an exhaust path 37 for exhausting gas is connected to the plurality of exhaust ports 104A to 104G. Air, nitrogen, and the like are preferable as the gas, and air is excellent in that the exposure apparatus can be used immediately because there is no need to replace the gas inside the closed space, and there is no waiting time until the completion of the replacement. Since nitrogen is an inert gas, it is excellent in that it does not obscure the mirrors and lenses.

The air supply path 36 and the exhaust path 37 are connected to a gas supply unit 35 that adjusts the flow rate or temperature of the gas, and supply and exhaust of the gas are regulated by the gas supply unit 35. The gas supply unit 35 controls the temperature of the gas to a constant temperature. In addition, the air supply path 36 and the exhaust path 37 may be one system or a plurality of systems, one system may be provided in one hole, or one system may be branched and connected to each hole. If there are multiple systems, the flow rate and temperature of the gas can be adjusted independently for each system. Further, the operation of the gas supply unit 35 is controlled by the control unit C.

Arrows 107 indicate the flow of gas before flowing into the air supply ports 103A to 103G. The plurality of arrows correspond to each of the plurality of air supply ports 103A to 103G. The gas temperature-controlled by the gas supply unit 35 is supplied from the plurality of air supply ports 103A to 103G. Arrow 108 indicates the flow of gas flowing out from the exhaust ports 104A to 104G, and the gas is exhausted from the exhaust ports 104A to 104G. In this way, a gas flow 109 is created in the closed space 102 between the convex mirror 15 and the meniscus lens 15', and the temperature in the closed space 102 is adjusted. The plurality of supply ports 103A to 103G and exhaust ports 104A to 104G are formed to a position covering the entire diameter of the convex mirror 15 and the meniscus lens 15' in the X direction. That is, the supply ports 103A and 103G and the exhaust ports 104A and 104G are disposed near the outer periphery of the convex mirror 15 or the meniscus lens 15'. Therefore, the temperature-controlled gas can be injected over the entire surface of the convex mirror 15 and the meniscus lens 15'. Further, since the plurality of air supply ports 103A to 103G and the exhaust ports 104A to 104G extend in the Z direction, the directions are aligned. In addition, the flow rate of the supply air and the flow rate of the exhaust air coincide. As a result, the gas flow path is aligned in the Z direction (one direction), and the gas flow does not stop in the closed space 102, so that the gas flows in the laminar flow 109. That is, gas flows on the surface of the convex mirror 15 or the meniscus lens 15' along the same direction from each of the plurality of air supply ports.

In this way, a temperature-controlled gas is supplied to the closed space 102 between the convex mirror 15 and the meniscus lens 15 ′, and the surface of the convex mirror 15 and the meniscus lens 15 ′ is By flowing the gas, the temperature distribution of the convex mirror 15 and the meniscus lens 15' can be adjusted. After continuously supplying the temperature-controlled gas to the closed space 102 between the convex mirror 15 and the meniscus lens 15', the convex mirror 15 and the meniscus lens in contact with the closed space 102 The temperature distribution of (15') is a temperature distribution that is symmetrical with respect to the Z-axis as shown in FIG. 6. 6 shows a schematic temperature distribution diagram of the convex mirror 15 and the meniscus lens 15'. Region 1 has the lowest temperature, region 2 has a higher temperature than region 1, and region 3 has the highest temperature. The convex mirror 15 and the meniscus lens 15' have heat by exposure, and the temperature increases as they move away from the gas supply port. It can be seen that in the region close to the air supply port, the temperature is lowered by the low-temperature gaseous gas. As the temperature distribution approaches the right and left symmetrical temperature distribution with respect to the Z-axis, the wavefront aberration of the Z5 term increases and the wavefront aberration of the Z6 term decreases. That is, compared to the case where no gas is supplied, the astigmatism in the vertical and horizontal direction becomes larger and the astigmatism in the oblique direction becomes smaller, so that the astigmatism in the vertical and horizontal direction and the direction of increase or decrease of the astigmatism in the oblique direction are opposite to each other. In the case of exposing the substrate with high illuminance, the temperature non-uniformity of the lens of the projection optical system increases, resulting in a large aberration. However, even in the case of exposing the substrate with high illuminance, by controlling the supply of the gas by the gas supply unit 35 as described above, the astigmatism in the oblique direction can be made to fall within the allowable range. As a specific example, as a result of continuously supplying a temperature-controlled gas to the space 102 between the convex mirror 15 and the meniscus lens 15' by the gas supply unit 35, the amount of astigmatism in the oblique direction is reduced. Was 2.5 μm.

In this way, the temperature distribution of the convex mirror 15 or the meniscus lens 15' is not made uniform as a whole, but the astigmatism in the oblique direction is reduced and the astigmatism in the vertical and horizontal direction is allowed to increase. Making a flow, adjusting the temperature distribution. Therefore, the astigmatism in the vertical and horizontal direction is not within the allowable range, but rather, it may become larger than before supplying the gas.

Next, a method of correcting astigmatism in the vertical and horizontal directions will be described. 7 shows a flowchart of the correction method. First, the control unit C controls the gas supply unit 35 to start supplying the temperature-controlled gas to the closed space 102 between the convex mirror 15 and the meniscus lens 15', as described above. , The temperature distribution of the convex mirror 15 and the meniscus lens 15' is adjusted (S301). While the substrate is continuously being supplied, the control unit C controls each unit of the exposure apparatus so that the projection optical system PO projects the pattern of the mask 9 onto the substrate 19 and exposes the substrate 19. For example, when the substrate is exposed with a high illuminance, the temperature of the lens of the projection optical system or the like becomes high, and aberration may not fall within the allowable range. When the gas is supplied in S301, the astigmatism in the oblique direction of the projection optical system falls within the allowable range, but the astigmatism in the vertical and horizontal direction does not fall within the allowable range. Therefore, the astigmatism in the vertical and horizontal directions is measured each time the substrate 19 after exposure is completed or for each lot (S302). Measurement of astigmatism can be performed using, for example, the focus sensor 40 (measurement unit) disposed on a substrate stage to move the substrate. And, based on the measurement result, that is, the measured amount of astigmatism in the vertical and horizontal directions, the cylindrical lenses 21, 22, 23, 24 and the plano-concave lens 12 for reducing the astigmatism in the vertical and horizontal directions within the allowable range. The amount of movement of the lens of any one of') is calculated (S303). Then, the lens is driven based on the calculated movement amount of the lens (S304). Then, the astigmatism in the vertical and horizontal direction and the astigmatism in the oblique direction can be made to fall within the allowable range. Then, the next substrate is exposed using the projection optical system in which the astigmatism is within the allowable range (S305).

In this way, the gas supply unit is provided with the second gas supply unit so that the increase or decrease of the astigmatism in the first direction caused by the temperature distribution of the second optical element during exposure and the astigmatism in the second direction different from the first direction are opposite to each other. The temperature of the second optical element is adjusted by flowing gas on the surface of the optical element. Further, the gas supply unit adjusts the temperature of the second optical element by flowing gas on the surface of the second optical element so that the astigmatism in the first direction falls within the allowable range. Further, the position or shape of the first optical element is controlled so that the astigmatism in the second direction at the time of exposure falls within the allowable range. Thereby, even when the illuminance is high, the astigmatism in the first direction and the astigmatism in the second direction of the projection optical system can be made to fall within the allowable range.

(2nd embodiment)

Next, an exposure apparatus according to a third embodiment will be described. The gas supply port and the exhaust port from the gas supply unit 35 are not limited to the holes formed in the barrel 100. In the present embodiment, a punching plate provided with a large number of holes is used on the side surface of the barrel 100. If it is a hole formed in the barrel 100, the manufacturing of the barrel 100 is easy. On the other hand, in the punching plate, cooling unevenness of temperature control can be effectively reduced. 8 shows a cross-sectional view of the barrel 100 provided with a punching plate. A large opening having a length equal to the diameter of the convex mirror 15 or the meniscus lens 15' is formed on the lower side of the barrel 100 in the z-axis direction, and a plurality of holes ( A punching plate 201 on which 204 is formed is provided. Further, a large opening is also formed on the upper side of the barrel 100 in the z-axis direction, and a punching plate 200 in which a number of holes 203 are formed is provided so as to cover the opening. Gas is supplied to the closed space 102 between the convex mirror 15 and the meniscus lens 15' through the hole of the punching plate 201, and the closed space 102 through the hole of the punching plate 200 Exhaust gas from In this way, gas is supplied from an opening having a length equal to the diameter of the convex mirror 15 or the meniscus lens 15 ′, and the gas is also exhausted, so that the convex mirror 15 or the meniscus lens ( 15'), gas can flow over the entire surface. Therefore, the convex mirror 15 and the meniscus lens 15' have a temperature distribution as shown in Fig. 6, and the astigmatism in the vertical and horizontal direction becomes larger than in the case where no gas is supplied, and the astigmatism in the oblique direction is increased. The astigmatism becomes smaller. Therefore, even in the case of exposing the substrate with high illuminance, the astigmatism in the oblique direction can be made to fall within the allowable range.

(3rd embodiment)

Next, an exposure apparatus according to a third embodiment will be described. In the first embodiment, the astigmatism in the vertical and horizontal direction was measured. In this embodiment, the change amount of the astigmatism in the vertical and horizontal direction is calculated from the information of the mask pattern and the accumulated exposure amount.

First, by experiment, a coefficient of change of astigmatism (exposure history coefficient) in the vertical and horizontal direction with respect to the accumulated exposure amount of the substrate is obtained. Specifically, an integrated exposure meter that detects light diverged from the optical path of the illumination optical system IL is used. A correspondence relationship between the illuminance of light branched from the optical path of the illumination optical system IL and the illuminance of light on the substrate has been obtained in advance. The illuminance measured by the integrated exposure meter during consecutive exposure periods is accumulated, and the integrated exposure amount on the substrate is indirectly determined based on the above correspondence. Further, when continuously exposed, the change in astigmatism in the vertical and horizontal direction is measured by the focus sensor 40 while measuring the accumulated exposure amount. Then, the control unit C obtains a coefficient of a change in astigmatism in the vertical and horizontal direction with respect to the accumulated exposure amount of the substrate using the measured data. This exposure history coefficient is stored in the memory of the control unit C. And, when actually exposing the substrate, instead of the measurement in S302 of FIG. 7, the control unit C uses the obtained exposure history coefficient, the information of the mask pattern, and the accumulated exposure amount when the substrate is actually exposed, in the vertical and horizontal direction. Calculate the amount of change in the astigmatism of. Then, the control unit C calculates a driving amount of a cylindrical lens or the like necessary for correcting the astigmatism in the vertical and horizontal directions. Then, the control unit C controls a driving unit that drives the lens based on the calculated driving amount.

According to the method of this embodiment, it is possible to predict the change in astigmatism in the vertical and horizontal directions during periods in which the focus sensor cannot measure the aberration, such as while the substrate is being moved to expose the substrate, and the lens is driven. Aberration can be corrected. Accordingly, it is possible to correct a change in astigmatism in the vertical and horizontal directions during one substrate processing or during one shot exposure.

(Product manufacturing method)

Next, a method of manufacturing an article (semiconductor IC element, liquid crystal display element, color filter, MEMS, etc.) using the above-described exposure apparatus will be described. The article uses the above-described exposure apparatus to expose a substrate (wafer, glass substrate, etc.) coated with a photosensitive agent, a process of developing the substrate (photosensitive agent), and the developed substrate in other known processing processes. It is manufactured by processing. Other known processes include etching, resist stripping, dicing, bonding, packaging, and the like. According to this manufacturing method, it is possible to manufacture an article of higher quality than before.

As described above, preferred embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist. In addition, although the explanation was made on the premise that the control unit C in the exposure apparatus performs calculation and control, a control unit outside the exposure apparatus may be used as the control unit. In addition, although an example in which one meniscus lens 15' is disposed in the vicinity of the convex mirror 15 has been described, a plurality of lenses may be disposed. In this case, gas is supplied to the space between the plurality of lenses, and the temperature distribution of the lenses is adjusted as described above. In addition, when the required exposure accuracy is low, it is not necessary to arrange a meniscus lens. In this case, the gas supply unit adjusts the temperature distribution of the convex mirror by flowing gas on the surface of the convex mirror. In addition, although a reflection type projection optical system has been described, it can also be applied to a refractive type projection optical system. In the case of a refractive type projection optical system, a temperature-controlled gas flows through a lens disposed in the vicinity of a pupil plane to generate astigmatism in one direction, and astigmatism in another direction is corrected by another optical element.

While the present invention has so far been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of the priority of Japanese Patent Application No. 2016-233244 filed on November 30, 2016, the entire contents of which are incorporated herein by reference.

Claims (14)

An exposure apparatus having a projection optical system that projects a pattern of a mask onto a substrate,
The projection optical system,
A first optical element whose position or shape can be changed to adjust the astigmatism of the projection optical system,
It has a second optical element arranged in the vicinity of the pupil plane or the pupil plane of the projection optical system,
The exposure apparatus,
A control unit for controlling the position or shape of the first optical element,
It has a supply portion for supplying a gas to the surface of the second optical element to adjust the temperature distribution of the second optical element,
The supply unit, the astigmatism in the first direction generated by the temperature distribution of the second optical element and the direction of increase or decrease of the astigmatism in a second direction different from the first direction are opposite to each other, and in the first direction. Supplying a gas to the surface of the second optical element so that the astigmatism falls within the allowable range,
The control unit controls the position or shape of the first optical element so that the astigmatism in the second direction falls within an allowable range. The method of claim 1,
The projection optical system has a holding portion for holding the second optical element,
The exposure apparatus, wherein the supply unit flows gas on the surface of the second optical element along the same direction from each of the plurality of air supply ports formed in the holding unit. The method of claim 2,
In the holding portion, each of the plurality of air supply ports extends in the same direction. The method of claim 2,
In the holding part,
A plurality of exhaust ports are formed on a side opposite to the air supply port with respect to the optical axis of the second optical element,
An exposure apparatus, wherein the plurality of air supply ports and the plurality of exhaust ports extend in the same direction. The method of claim 1,
By controlling the position or shape of the first optical element by the control unit, it is possible to adjust the projection magnification of the projection optical system in a direction perpendicular to each other, and also, it is possible to adjust the astigmatism in the second direction. Exposure device to do. The method of claim 1,
It has a measurement unit that measures astigmatism in the second direction of the projection optical system,
An exposure apparatus, characterized in that, based on a measurement result by the measurement unit, the position or shape of the first optical element is controlled so that the astigmatism in the second direction falls within an allowable range. The method of claim 1,
The control unit, based on the exposure history of the substrate by the projection optical system, calculates a driving amount of the first optical element necessary to make the astigmatism in the second direction fall within an allowable range, and the calculated driving amount is An exposure apparatus, characterized in that controlling driving of the first optical element on the basis of. The method of claim 1,
The exposure apparatus, wherein the second direction is a direction different from the first direction by 45 degrees. The method of claim 1,
The projection optical system has a concave mirror, a convex mirror, and a lens disposed between the concave mirror and the convex mirror and held so as to form a space between the convex mirror,
An exposure apparatus, wherein the second optical element is a convex mirror or a lens. The method of claim 9,
And the supply unit supplies gas to the space between the convex mirror and the lens. An exposure apparatus having a projection optical system that projects a pattern of a mask onto a substrate,
The projection optical system,
A first optical element whose position or shape can be changed to adjust the astigmatism of the projection optical system,
It has a second optical element arranged in the vicinity of the pupil plane or the pupil plane of the projection optical system,
The exposure apparatus,
A control unit for controlling the position or shape of the first optical element,
It has a supply portion for supplying a gas to the surface of the second optical element to adjust the temperature distribution of the second optical element,
The supply unit, so that the astigmatism in the first direction generated by the temperature distribution of the second optical element falls within an allowable range, and the astigmatism in the second direction crossing the first direction becomes larger than before supplying the gas. , Supplying a gas to the surface of the second optical element,
The control unit controls the position or shape of the first optical element so that the astigmatism in the second direction falls within an allowable range. An exposure apparatus having a projection optical system that projects a pattern of a mask onto a substrate,
The projection optical system,
A first optical element that can be driven to adjust the astigmatism of the projection optical system,
It has a second optical element in which a non-uniform temperature distribution occurs at the time of exposure,
The exposure apparatus,
A driver for driving the first optical element,
It has a supply portion for supplying a gas to the surface of the second optical element to adjust the temperature distribution of the second optical element,
The supply unit, the astigmatism in the first direction generated by the temperature distribution of the second optical element and the direction of increase or decrease of the astigmatism in a second direction different from the first direction are opposite to each other, and in the first direction. Supplying a gas to the surface of the second optical element so that the astigmatism falls within the allowable range,
The exposure apparatus, wherein the driving unit drives the first optical element so that the astigmatism in the second direction falls within an allowable range. An exposure apparatus having a projection optical system that projects a pattern of a mask onto a substrate,
The projection optical system,
A first optical element that can be driven to adjust the astigmatism of the projection optical system,
It has a second optical element in which a non-uniform temperature distribution occurs at the time of exposure,
The exposure apparatus,
A driver for driving the first optical element,
It has a supply portion for supplying a gas to the surface of the second optical element to adjust the temperature distribution of the second optical element,
The supply unit, so that the astigmatism in the first direction generated by the temperature distribution of the second optical element falls within an allowable range, and the astigmatism in the second direction crossing the first direction becomes larger than before supplying the gas. , Supplying a gas to the surface of the second optical element,
The exposure apparatus, wherein the driving unit drives the first optical element so that the astigmatism in the second direction falls within an allowable range. It is a manufacturing method for manufacturing an article,
A step of exposing a substrate using the exposure apparatus according to any one of claims 1 to 13, and
A process of developing the exposed substrate, and
A manufacturing method comprising a step of manufacturing the article by processing the developed substrate.

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