TW201350902A - Optical system, exposure apparatus and manufacturing method for equipment - Google Patents

Abstract

An optical system is disclosed, which is configured with the followings in sequence along an optical path: a first optical element, a second optical element, a third optical element, and a fourth optical element. A space is formed between the abovementioned third optical element and the fourth optical element. The abovementioned optical system is provided with a component for separating the optical path between the first optical element and the second optical element and the abovementioned space.

Description

Optical system, exposure device, and method of manufacturing the same

The present invention relates to an optical system, an exposure apparatus, and a method of manufacturing an apparatus using the exposure apparatus, which are used in an optical lithography process used in manufacturing a liquid crystal display element and a semiconductor element.

In recent years, liquid crystal display substrates have been widely used in display devices such as personal computers and televisions. A liquid crystal display substrate was produced by forming a transparent thin film electrode pattern into a desired shape on a glass substrate by using a photolithography project. In order to perform photolithography, a projection exposure apparatus is used which irradiates exposure light on a mask that draws a desired pattern in advance, and projects a pattern on the mask to a coating photoresist via a projection optical system. The substrate is exposed on a substrate such as a glass substrate. In the manufacture of a liquid crystal display substrate, a projection exposure apparatus by mirror projection is used.

A conventional projection-projection type projection exposure apparatus disclosed in Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. 2008-89832. The illumination optical system 101 illuminates the light emitted from the high-pressure mercury lamp placed inside the illumination optical system 101 into a desired shape, and illuminates the mask 102 that draws the pattern. From illumination optics The light of the system 101 is illuminating the reticle 102 and then incident on the lens barrel 103 in which the projection optical system is housed. The light incident into the lens barrel 103 is reflected by the plane mirror 131 and the concave mirror 132, and is guided to the vicinity of the pupil of the projection optical system. A meniscus lens 133 and a convex mirror 134 are provided in the vicinity of the pupil of the projection optical system.

The light reflected by the plane mirror 131 and the concave mirror 132 passes through the meniscus lens 133, is reflected by the convex mirror 134, and passes through the meniscus lens 133 again. The light that has passed through the lenticular lens 133 is again reflected by the concave mirror 132 and the plane mirror 131, and reaches the substrate 104 on which the sensitizer is applied. At the position of the substrate 104, the transmitted light from the reticle 102 and the diffracted light interfere, and the pattern of the reticle 102 is imaged to expose the substrate 104. The mask 102 and the plate 104 are respectively disposed on the mask workpiece stage and the substrate workpiece stage (not shown), and the mask workpiece stage and the substrate workpiece stage are simultaneously scanned and exposed, whereby the substrate 104 of the large screen can be realized. exposure.

In recent years, liquid crystal display substrates have become larger and larger, and in response to the demand, the exposure area of the exposure apparatus has also expanded. When the exposure area is increased, the amount of light per unit area becomes small, the time required for exposure becomes long, and the productivity as an exposure apparatus is lowered. Therefore, a large-sized mercury lamp having an output of about 10 kW as a light source for exposure is used, and high illumination is suppressed and exposure time is suppressed.

Due to the large increase in the number of large-scale mercury lamps, a very high thermal load is generated inside the projection optical system of the exposure apparatus in the exposure engineering. Specifically, a part of the exposure light is formed as an optical part of the projection optical system. Absorbing, the optical components accumulate heat, which is again released into the lens barrel, whereby the temperature of the optical components and the gas surrounding the optical components rises. If the temperature of the gas around the optical component and the optical component rises, the gas oscillates due to the convection of the gas in the vicinity of the surface of the optical component, and the shift of the forward path of the light passing through the oscillating gas (image swing) occurs. . Further, the gas whose temperature rises is accumulated in the upper portion of the lens barrel in which the projection optical system is mounted, and the gas inside the lens barrel has a temperature gradient in the vertical direction.

In the mirror projection type exposure apparatus shown in FIG. 4, the condensing degree is the highest in the vicinity of the convex mirror 134 which becomes the pupil of the projection optical system, and it becomes high temperature. Therefore, the space between the meniscus lens 133 and the convex mirror 134 is high, and since the space is not a closed structure, a convective airflow is generated upward from the vicinity of the convex mirror 134, and an oscillating motion of the image is formed. The imaging performance is considered to be a problem due to the temperature gradient of the gas in the projection optical system generated in the exposure process and the swing of the gas near the surface of the optical component.

Accordingly, the present invention provides an optical system that reduces the effects of ambient gases of a portion of the optical path on other portions of the optical path.

According to a first aspect of the present invention, in an optical system in which first optical elements, second optical elements, third optical elements, and fourth optical elements are arranged in order along an optical path, the third optical element and the first 4 Space is formed between the optical elements, and the aforementioned optical system is provided for separation An optical path between the first optical element and the second optical element and a member of the space.

According to a second aspect of the present invention, there is provided an exposure apparatus for projecting a pattern formed on a photomask to a substrate through a projection optical system and exposing the substrate, wherein the projection optical system includes the optical system according to the first aspect.

A third aspect of the present invention provides a method of manufacturing a device, comprising: exposing a substrate using the exposure apparatus of the second aspect; developing the exposed substrate; and processing the developed substrate to manufacture The aforementioned equipment.

Further features of the present invention will become apparent from the following description of exemplary embodiments.

1‧‧‧Lighting optical system

2‧‧‧Photomask

3‧‧‧Projection Optics

4‧‧‧Substrate (board)

31‧‧‧ Planar mirror (first optical element)

32‧‧‧ concave mirror (2nd optical element)

33‧‧‧ lenticular lens (third optical element)

34‧‧‧ convex mirror (fourth optical element)

35‧‧‧Mirror tube

36‧‧‧Light absorbing members

37‧‧‧Condition piping

38‧‧‧Pipe

39‧‧‧ Space

Fig. 1 is a schematic view showing an exposure apparatus of the present invention.

Fig. 2 is a detailed view showing the vicinity of a convex mirror in Fig. 1;

Fig. 3 is a view showing the vicinity of a convex mirror viewed from the side of the concave mirror 32 in Fig. 1;

4 is a schematic view showing a conventional exposure apparatus.

[exposure device]

Hereinafter, an embodiment of an exposure apparatus according to the present invention will be described with reference to Fig. 1 . Illumination optical system 1 for illuminating the reticle 2, internally packaged Including: high-pressure mercury lamp, elliptical mirror, shaping optical system, ND filter, optical integrator, concentrating lens and other optical components. The elliptical mirror concentrates the light emitted by the high-pressure mercury lamp in a specific direction. The shaping optics distributes the light from the elliptical mirror into a desired shape. The ND filter is used to adjust the light intensity. The optical integrator will distribute the light intensity on both sides of the mask. A concentrating lens is a condensing light that passes through an optical integrator.

The exposure light emitted by the illumination optical system is irradiated to a photomask (also referred to as a negative film) 2 on which a pattern to be transferred is drawn. The light transmitted through the reticle 2 reaches the substrate (plate) 4 via the projection optical system 3, and the pattern on the reticle 2 is transferred onto the plate 4 to expose the plate 4. A photosensitive agent is applied to the plate 4 in advance, and a desired pattern can be produced on the plate 4 by performing appropriate treatment before and after the exposure.

In the projection optical system 3, the optical path from the mask 2 to the plate 4 is arranged in order: a plane mirror (first optical element) 31, a concave mirror (second optical element) 32, and a meniscus lens (third Optical element 33, convex mirror (fourth optical element) 34. In the present embodiment, the light incident on the projection optical system 3 through the mask 2 is refracted by the plane mirror 31, is reflected by the concave mirror 32, passes through the meniscus lens 33, and enters the convex mirror 34. The light reflected by the convex mirror 34 is again transmitted through the meniscus lens 33, and is again reflected by the concave mirror 32 and the plane mirror 31, and is incident on the plate 4. The plane mirror 31, the concave mirror 32, the meniscus lens 33, and the convex mirror 34 are arranged in order along the optical path: the first optical element and the second optical element The optical system of the third optical element and the fourth optical element.

In the projection optical system 3 of the mirror projection type exposure apparatus described in the present embodiment, the meniscus lens 33 is disposed on the upstream side of the optical path, and the convex mirror 34 is disposed on the downstream side of the optical path. In the projection optical system 3 of the mirror projection type exposure apparatus, the meniscus lens 33 and the convex mirror 34 are disposed in the vicinity of the pupil of the projection optical system 3. Since the convexity of the convex mirror 34 is the highest, the amount of heat generation is also large. A space 39 is formed between the meniscus lens 33 and the convex mirror 34 so that heat generated by the reflection film by the reflection film irradiated onto the surface of the convex mirror 34 is hardly transmitted to the meniscus lens 33. The meniscus lens 33 and the convex mirror 34 are fixed by the lens barrel 35, and the space 39 is surrounded by the lunar meniscus lens 33, the convex mirror 34, and the lens barrel 35. Therefore, the gas in the space 39 which is heated by the heat generated by the reflecting film portion is not released from the space 39, and the optical path between the plane mirror 31 and the concave mirror 32 is not generated. The swing of the gas. The lens barrel 35 is a member that constitutes an optical path and a space 39 between the separation plane mirror (first optical element) 31 and the concave mirror (second optical element).

The material of the lens barrel 35 is a material that is excellent in heat insulation, and it is difficult to transmit heat to the outside. The light absorbing member 36 is disposed on the side opposite to the meniscus lens 33 (the downstream side of the optical path) via the convex mirror 34 with a space interposed therebetween. The light absorbing member 36 is light that is transmitted through the surface of the convex mirror 34 and transmitted through the convex mirror 34. A space is interposed between the convex mirror 34 and the light absorbing member 36 in order to absorb the difference in thermal expansion coefficient between the convex mirror 34 and the light absorbing member 36, and to make the light absorbing structure The heat generated by the member 36 is difficult to transfer to the convex mirror 34.

A reflection film is formed on the reflection surface of the convex mirror 34 in order to reflect light. The material of the reflective film is preferably a dielectric material compared to a metal such as aluminum. The reason why the dielectric is selected is that the light absorption is small when the film of the dielectric is irradiated with light compared with the metal film. When a dielectric is selected as the material of the reflective film, the lens for fixing the convex mirror 34 is fixed because the amount of light directly transmitted is not reflected by the light reflecting surface of the convex mirror 34 as compared with the metal film. 35 may have fever. As a result, the temperature in the vicinity of the convex mirror 34 rises, and the oscillation of the gas occurs in the optical path inside the projection optical system 3, and the imaging performance of the projection optical system 3 is lowered.

An enlarged view of the vicinity of the convex mirror 34 is shown in Fig. 2 . In the light absorbing member 36, a refrigerant pipe 37 is provided, and the refrigerant pipe 37 includes a liquid supply unit that supplies a liquid (refrigerant) whose temperature is controlled to the inside of the light absorbing member 36, and a liquid discharge unit that discharges the liquid from the inside, and In order to prevent the light absorbing member 36 from being overheated, the refrigerant may be caused to flow in the direction of the arrow in FIG. The refrigerant piping 37 is led back to the outside of the projection optical system 3, and is circulated while controlling the temperature of the refrigerant to be constant using a refrigerator or the like not shown. The refrigerant may be circulated frequently, or may be circulated only when the temperature of the light absorbing member 36 is higher than a certain critical value. By providing the refrigerant pipe 37, the temperature rise of the light absorbing member 36 can be minimized, and the oscillation of the gas in the optical path inside the projection optical system 3 can be suppressed. The light absorbing member 36 uses a substance having a high thermal conductivity such as aluminum. The refrigerant flowing through the refrigerant piping 37 is, for example, a fluorine-based inert liquid.

Next, a method of cooling the space 39 between the meniscus lens 33 and the convex mirror 34 will be described with reference to FIG. 3 is a cross-sectional view of the space 39 and the lens barrel 35 viewed from the concave mirror 32 side. If the exposure is continued, the temperature of the space 39 between the meniscus lens 33 and the convex mirror 34 gradually rises. As a result, a temperature distribution occurs in the space 39, and image shift, astigmatism, and the like occur. In order to prevent occurrence of image shift, astigmatism, and the like, a pipe 38 is connected to the lens barrel 35, and a gas such as air or nitrogen gas whose temperature is controlled can be supplied to the space 39 between the meniscus lens 33 and the convex mirror 34 via the pipe 38. . The pipe 38 is led back by the outside of the projection optical system 3. The temperature management of the space 39 between the meniscus lens 33 and the convex mirror 34 can be effectively performed by adjusting the flow rate of the gas or adjusting the shape of the gas ejection port to the inside of the lens barrel 35. The arrow in Fig. 3 is a mode in which the mode indicates that the gas efficiently flows through the space 39 between the meniscus lens 33 and the convex mirror 34. The gas flowing through the pipe 38 is, for example, air or an inert gas.

In the structure of the pipe 38 of FIG. 3, the number of the gas supply unit that supplies the gas to the space 39 and the gas discharge unit that discharges the gas from the space 39 is one. However, the gas supply unit may be provided without being limited to this number. The number of gas discharge portions is set to be plural. Further, the flow of the gas is in the horizontal direction, but in this case, even when it is disposed in a direction other than the horizontal direction, a certain effect can be obtained.

[Device Manufacturing Method]

Next, a device (semiconductor) for one of the embodiments of the present invention The manufacturing method of the device, the liquid crystal display device, etc.) will be explained. Here, a method of manufacturing a semiconductor device will be described as an example.

The semiconductor device is manufactured by a post-engineering process in which a built-in circuit on a substrate is fabricated on a substrate and an integrated circuit wafer on a substrate produced in the prior art is used as a product. The pre-engineering includes the process of scanning and exposing the substrate on which the sensitizer is applied, and the process of developing the substrate, using the aforementioned exposure apparatus. Post-engineering includes: assembly engineering (cutting, joining), and packaging engineering (sealing). Further, the liquid crystal display device is manufactured by a process of forming a transparent electrode. The process of forming a transparent electrode includes a process of applying a photosensitive agent on a glass substrate on which a transparent conductive film is vapor-deposited, a process of scanning and exposing a glass substrate on which a photosensitive agent is applied by exposure, and a process of developing a glass substrate. According to the apparatus manufacturing method of the present embodiment, at least one of the productivity and quality of the equipment is advantageous over the conventional technology.

The present invention has been described with respect to the embodiments shown in the drawings, but it should be understood that the invention is not limited to the illustrated embodiments. In the scope of the following patent application, all variations and equivalent designs, such as composition and function, should be interpreted the broadest.

1‧‧‧Lighting optical system

2‧‧‧Photomask

3‧‧‧Projection Optics

4‧‧‧Substrate (board)

31‧‧‧ Planar mirror (first optical element)

32‧‧‧ concave mirror (2nd optical element)

33‧‧‧ lenticular lens (third optical element)

34‧‧‧ convex mirror (fourth optical element)

35‧‧‧Mirror tube

36‧‧‧Light absorbing members

39‧‧‧ Space

Claims (10)

An optical system is disposed in order along an optical path: a first optical element, a second optical element, a third optical element, and a fourth optical element; and the third optical element and the fourth optical element are A space is formed therebetween; the optical system includes means for separating the optical path between the first optical element and the second optical element and the space. The optical system according to claim 1, wherein the member surrounds the space together with the third optical element and the fourth optical element. The optical system according to claim 2, further comprising: a gas supply unit that supplies a gas whose temperature is controlled to the surrounding space, and a gas discharge unit that discharges the aforementioned space from the space gas. The optical system according to claim 1, wherein the third optical element is disposed on an upstream side of the optical path as compared with the fourth optical element, and the optical system is provided on a downstream side of the fourth optical element of the optical path. A light absorbing member that absorbs light transmitted through the fourth optical element. The optical system according to claim 4, further comprising: a liquid supply unit that supplies a liquid whose temperature is controlled to the inside of the light absorbing member, and a liquid discharge unit that is from the light The inside of the absorbing member discharges the aforementioned liquid. The optical system according to claim 1, wherein the third optical element and the fourth optical element are disposed in the vicinity of an aperture of the optical system. The optical system according to claim 1, wherein the first optical element is a planar mirror, the second optical element is a concave mirror, the third optical element is a meniscus lens, and the fourth optical element is a convex mirror. . The optical system according to claim 7, wherein the reflecting surface of the convex mirror is formed of a film of a dielectric. An exposure apparatus for projecting a pattern formed on a reticle to a substrate via a projection optical system and exposing the substrate; wherein the projection optical system includes: one of request item 1 to claim item 8 The optical system described. A method of manufacturing a device comprising: exposing a substrate using the exposure device of claim 9; developing the exposed substrate; and processing the developed substrate to fabricate the device.