JP2021026021A - Optical device, projection optics system, and manufacturing method of exposure apparatus and article - Google Patents

Abstract

To provide an optical device equipped with a gas supply mechanism that reduces a risk that light to an optical element is shaded.SOLUTION: An optical device includes a first optical element, a second optical element, a holding unit for holding the first optical element and the second optical element, a gas supply unit for supplying a temperature-controlled gas toward a flow channel formed in the holding unit, and a gas discharge unit for discharging the gas supplied by the gas supply unit. The gas discharging unit is installed along the arranging direction of the first optical element and the second optical element.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical device, a projection optical system, an exposure device, and a method for manufacturing an article.

It is known that in an optical device using an optical element such as a lens or a mirror, the optical performance of the optical device can be affected by a change in the temperature of the optical element or the space in the optical path. This can occur due to a change in the surface shape of the optical element, thermal deformation in the holding portion of the optical element, or a change in the refractive index of air.

As one of the factors of the temperature change of the optical element and the space in the optical path as described above, the light incident on the optical element can be mentioned. When light passes through an optical element or is reflected by the optical element, heat is generated by absorbing a part of the light by the optical element. Part of the generated heat is transferred to the holding portion of the optical element and the space around the optical element. In particular, when an optical path exists near the holding portion, natural convection may occur as the temperature of the holding portion rises, and heat may be transferred from the holding portion to the space including the optical path. As a result, the refractive index of the gas in the optical path changes, which may lead to deterioration of the optical performance of the optical device.

A cooling mechanism for cooling an optical element and a space in the vicinity thereof is known in order to suppress a decrease in optical performance in an optical device. Patent Document 1 discloses a gas supply mechanism that supplies and discharges a gas for temperature control to a space between two optical elements.

JP-A-2018-91919

In the gas supply mechanism of Patent Document 1, since the gas supply mechanism is arranged in the vertical direction of the two optical elements, the light is blocked by the gas supply mechanism depending on the optical path of the light reaching each optical element. There is a risk. By devising the arrangement of the gas supply mechanism, it is possible to reduce the risk that the light reaching the optical element is blocked.

It is an exemplary object of the present invention to provide an optical device provided with a gas supply mechanism that reduces the risk that light reaching an optical element is blocked.

The optical device of the present invention has a first optical element and a second optical element, a holding portion for holding the first optical element and the second optical element, and a flow path provided in the holding portion. A gas supply unit that supplies a gas whose temperature is controlled toward the surface and a gas discharge unit that discharges the gas supplied by the gas supply unit are provided, and the gas discharge unit includes the first optical element and the first optical element. It is characterized in that the two optical elements are arranged side by side in the arrangement direction.

According to the present invention, it is possible to provide an optical device provided with a gas supply mechanism that reduces the risk that light reaching the optical element is blocked.

It is the schematic which shows the whole structure of the exposure apparatus. It is a figure which shows the structure of the optical apparatus of Example 1. FIG. It is a figure which looked at the optical apparatus from the Y-axis direction. It is a figure which shows the structure of the optical apparatus of Example 2. It is a figure which shows the structure of the optical apparatus of Example 3. It is a figure which shows the structure of the optical apparatus as a comparative example.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, the same members are assigned the same reference numbers, and duplicate description will be omitted.

FIG. 1 is a schematic view showing the configuration of an exposure apparatus 1 including a projection optical system equipped with the optical apparatus of the present invention. The exposure apparatus 1 is used in a photolithography process, which is a manufacturing process for devices such as semiconductor devices and liquid crystal display devices. In the exposure apparatus 1, the mask pattern is projected onto the photosensitive material on the substrate by using the exposure light having a high light intensity. Therefore, the optical elements such as the lens and the mirror included in the exposure apparatus 1 absorb the exposure light. Easy to get warm.

The exposure apparatus 1 includes an illumination optical system IL, a projection optical system PO, a mask stage MS that holds and moves the mask M, and a substrate stage WS that holds and moves the substrate W. Further, the exposure apparatus 1 includes a control unit C that controls an exposure process on the substrate W, and projects a pattern of the mask M onto a resist film (photosensitive agent) on the substrate via a projection optical system PO to obtain a latent image (a latent image). An exposure process for forming a latent image pattern) is performed.

The light emitted from a light source (not shown) is shaped into, for example, arc-shaped light long in the X direction by a slit (not shown) included in the illumination optical system IL. The mask M and the substrate W are held by the mask stage MS and the substrate stage WS, respectively, and are arranged at positions substantially conjugate with each other via the projection optical system PO. The mask M is located on the object surface of the projection optical system PO, and the substrate W is located on the image plane of the projection optical system.

The projection optical system PO projects the pattern formed on the mask M onto the substrate W at a predetermined projection magnification. The mask M is formed by performing exposure processing while scanning the mask stage MS and the substrate stage WS in a direction parallel to the object surface of the projection optical system PO at a speed ratio corresponding to the projection magnification of the projection optical system PO. The patterns can be sequentially transferred onto the substrate W.

The projection optical system PO includes a trapezoidal mirror G1, a concave mirror G2, a convex meniscus lens G3, and a convex mirror G4. The exposure light L emitted from the illumination optical system IL and transmitted through the mask M has an optical path bent by the first surface G1a of the trapezoidal mirror G1 and is incident on the first concave reflection surface G2a of the concave mirror G2. The exposure light L reflected by the first concave reflection surface G2a is reflected on the convex reflection surface of the convex mirror G4 after passing through the meniscus lens G3, and is incident on the second concave reflection surface G2b of the concave mirror G2. The exposure light L reflected by the second concave reflecting surface G2b has an optical path bent by the second surface G1b of the trapezoidal mirror G1 and is imaged on the substrate W.

In FIG. 1, the concave mirror G2 is a single mirror, and the first concave reflection surface G2a and the second concave reflection surface G2b are the same surface. As another configuration example, the concave mirror G2 may be divided into a first concave mirror having a first concave reflection surface G2a and a second concave mirror having a second concave reflection surface G2b.

In the projection optical system PO in FIG. 1, the reflecting surface of the convex mirror G4 is an optical pupil. Since the light diameter of the exposure light L becomes smaller near the meniscus lens G3 and the convex mirror G4, the light intensity of the light transmitted through the meniscus lens G3 and the light reflected by the convex mirror G4 becomes stronger. Therefore, the meniscus lens G3 and the convex mirror G4 are easily warmed, and the lens barrel as a holding portion for holding them is also easily warmed.

When heat is conducted to the lens barrel, natural convection occurs and the heat tends to spread around the lens barrels 103 and 104. Here, in the vicinity of the lens barrels 103 and 104, there are optical paths of the exposure light L from the trapezoidal mirror G1 to the concave mirror G2 and the optical path of the exposure light L from the concave mirror G2 to the trapezoidal mirror G1. When heat spreads around the lens barrel, the refractive index of the space in the optical path of the exposure light L changes, which tends to cause deterioration of the imaging performance of the projection optical system PO.

The present invention relates to an optical device capable of reducing heat diffusion around the lens barrel by efficiently cooling the lens barrel, which is a holding portion of an optical element such as a lens or a mirror, and the optical element. It is a thing. Hereinafter, the detailed configuration of the optical device will be described.

(Example 1)
The optical device 100 of the first embodiment will be described with reference to FIG. The optical device 100 includes a meniscus lens 101 as a first optical element, a convex mirror 102 as a second optical element, a lens barrel 103 as a holding portion for holding the meniscus lens 101, and a holding portion for holding the convex mirror 102. Has a lens barrel 104 of. In FIG. 2, the lens barrel 103 and the lens barrel 104 have separate configurations, but the lens barrel 103 and the lens barrel 104 may be integrated into one lens barrel.

Further, the first optical element is not limited to the meniscus lens, and may be a lens having another shape or a mirror. Similarly, the second optical element is not limited to the convex mirror, and may be a mirror having another shape, a lens, or the like. Further, the number of optical elements is not limited to two, and the optical device 100 may include three or more optical elements.

The optical device 100 of FIG. 2 shows a specific configuration in the vicinity of the meniscus lens G3 and the convex mirror G4 in FIG. The exposure light L passes near the lens barrels 103 and 104, the exposure light L transmitted through the meniscus lens 101 is reflected by the reflection surface 102a of the convex mirror 102, and the exposure light L reflected by the reflection surface 102a is again meniscus. The state of transmitting through the lens 101 is shown.

The optical device 100 includes a gas supply unit 105 that supplies a temperature-controlled gas to the internal spaces of the lens barrels 103 and 104. The gas supply unit 105 supplies gas to the flow path 106 provided in the holding unit 104 of the convex mirror 102. That is, the gas supply unit 105 supplies gas in the Y direction, which is the arrangement direction of the meniscus lens 101 and the convex mirror 102. By directly supplying the temperature-controlled gas toward the flow path 106, the gas can be efficiently supplied to the internal spaces of the lens barrels 103 and 104, and as a result, the meniscus lens 101, the convex mirror 102, etc. are efficiently supplied. Can be cooled.

The gas supply unit 105 is arranged outside the optical path of the exposure light L so as not to block the optical path of the exposure light L. In FIG. 2, the gas supply unit 105 is arranged on the side opposite to the meniscus lens 101 with respect to the convex mirror 102.

The optical device 100 includes a gas discharge unit 107 that discharges gas from the internal spaces of the lens barrels 103 and 104. The gas discharge unit 107 discharges gas through an opening provided in the plate-shaped member 108. The plate-shaped member 108 is made of aluminum or the like and is fixed to the lens barrel 104. The plate-shaped member 108 separates the internal space of the lens barrels 103 and 104 from the external space thereof, and the opening provided in the plate-shaped member 108 communicates the internal space and the external space of the lens barrels 103 and 104. There is. The gas discharge portion 107 includes a connection portion 107a connected to the plate-shaped member 108, a pipe 107b, and an exhaust mechanism 107c, and the exhaust action of the exhaust mechanism 107c causes the internal space of the lens barrels 103 and 104 to pass through the pipe 107b. Gas is discharged.

FIG. 3A is a view of the optical device 100 shown in FIG. 2 as viewed from the negative direction of the Y-axis. A plurality of gas supply units 105 are provided for the lens barrel 104, and temperature-controlled gas is supplied from each gas supply unit 105 to the internal spaces of the lens barrels 103 and 104. Although five gas supply units 105 are provided in FIG. 3A, the number of gas supply units 105 is not limited to this, and at least one gas supply unit 105 may be provided. Further, two gas discharge portions 107 are provided for the plate-shaped member 108. Regarding the number of gas discharge units 107, it is sufficient that at least one gas discharge unit 107 is provided.

The lens barrel 104 is provided with a plurality of protrusions, and the convex mirror 102 is held by the lens barrel 104 by pressing the convex mirror 102 against these protrusions. With respect to the region where the protrusion does not exist, a gap is formed between the lens barrel 104 and the convex mirror 102. The gap functions as a gas flow path.

The gas supplied from the gas supply unit 105 moves to the internal space of the lens barrels 103 and 104 via the flow path 106. Then, the supplied gas passes through the space between the meniscus lens 101 and the convex mirror 102 and the gap between the lens barrel 104 and the convex mirror 102 by the exhaust action of the gas discharge unit 107, and then passes through the plate-shaped member 108. It is discharged to the external space through the provided opening.

FIG. 3B is a view of the optical device 100 shown in FIG. 2 viewed from the positive direction of the Y-axis, and the meniscus lens 101 is not shown. The three protrusions 110 formed on the surface 103a in FIG. 2 project in the positive direction of the Y-axis and position the surface 101a provided on the meniscus lens 101. The protrusion 111 in FIG. 3B is fixed to the surface 103b of the lens barrel 103, and the protrusion 111 supports the meniscus lens 101. A gap is formed between the surface 103a of the lens barrel 103 and the surface 101a of the meniscus lens 101, and between the surface 103b of the lens barrel 103 and the surface 101b of the meniscus lens 101, respectively.

Subsequently, the operation and effect of the optical device 100 of this embodiment will be described as compared with the comparative example. FIG. 6 shows an optical device 600 as a comparative example. The same reference numbers are assigned to the configurations common to the optical device 100 shown in FIG. FIG. 6 shows how the heat generated by the meniscus lens 101 and the convex mirror 102 due to the exposure light L is transferred to the lens barrels 103 and 104 and spreads around the lens barrels 103 and 104 as natural convection. .. In the optical device 600, the cover 601 is provided on the upper portions of the lens barrels 103 and 104 to reduce the diffusion of heat to the surroundings of the lens barrels 103 and 104.

By providing the gas discharge portion 602 on the cover 601, it is possible to more effectively reduce the diffusion of heat around the lens barrels 103 and 104. The gas discharge unit 602 is connected to the exhaust mechanism via a pipe. Gas is discharged from the internal space of the cover 601 by the exhaust action of the exhaust mechanism.

As shown in FIG. 6, by arranging the cover 601 around the lens barrels 103 and 104, heat diffusion to the surroundings of the lens barrels 103 and 104 can be reduced, but there is a space around the lens barrels. Often there are restrictions. For example, as shown in FIG. 1, there is an optical path of the exposure light L around the lens barrel, and by arranging the cover 601 there is a possibility that at least a part of the exposure light L is blocked.

In this embodiment, the gas discharge unit 107 is arranged not in the upper part of the lens barrels 103 and 104 but in the arrangement direction of the optical elements held by the lens barrels. Therefore, it is possible to avoid increasing the size of the optical element in the radial direction without blocking the exposure light L.

Returning to FIG. 2, other configurations of the optical device 100 will be described. The lens barrel 103 is provided with an opening for sucking gas from the external space of the lens barrel 103. As described above, the gas discharge unit 107 is connected to the exhaust mechanism 107c via the pipe 107b, and the gas is discharged from the internal spaces of the lens barrels 103 and 104 by the exhaust action of the exhaust mechanism 107c. At this time, the internal space of the lens barrel is in a negative pressure state with respect to the external space. Therefore, as shown by an arrow in FIG. 2, the gas in the external space of the lens barrel 103 is sucked into the internal space of the lens barrel 103 through the opening provided in the lens barrel 103.

The gas sucked into the internal space of the lens barrel 103 moves toward the gas discharge unit 107 through the gap provided between the lens barrel 103 and the meniscus lens 101. As a result, the cooling power of the lens barrel 103 and the meniscus lens 101 can be strengthened. The gas in the external space of the lens barrel 103 is preferably a gas whose temperature is controlled by a temperature adjusting mechanism (not shown). The gas in the external space of the lens barrel 103 is preferably a gas controlled so as to have the same temperature as the gas supplied from the gas supply unit 105.

Further, the exhaust force in each exhaust mechanism 107c and each gas supply so that the total flow rate of the gas discharged by each gas discharge unit 107 is larger than the total flow rate of the gas supplied from each gas supply unit 105. The amount of gas supplied in unit 105 is controlled. An amount of gas corresponding to the difference between the total flow rate of the gas discharged by each gas discharge unit 107 and the total flow rate of the gas supplied by each gas supply unit 105 is discharged from the opening provided in the lens barrel 103. It is sucked into the internal space of the lens barrel 103.

It has been confirmed by thermo-fluid analysis that the temperature rise of the lens barrels 103 and 104 can be reduced by configuring the gas to be supplied into the lens barrel through the opening provided in the lens barrel. In our analysis results, the temperature rise can be suppressed to about 50% as compared with the case where the opening is not provided.

(Example 2)
Next, the configuration of the optical device 400 of the second embodiment will be described with reference to FIG. In the optical device 400 of the second embodiment, the number of openings provided in the lens barrel 103 is increased as compared with the optical device 100 of the first embodiment. Specifically, the opening 115 is also provided in the vertical direction (Z-axis direction) of the lens barrel 103. As a result, the amount of gas sucked from the external space of the lens barrels 103 and 104 into the internal space increases, so that the cooling power of the lens barrels 103 and 104, the meniscus lens 101 and the convex mirror 102 can be further strengthened.

(Example 3)
Next, the configuration of the optical device 500 of the third embodiment will be described with reference to FIG. In the optical device 500 of the third embodiment, the arrangement of the gas discharge unit is changed as compared with the optical device 100 of the first embodiment. Specifically, the gas discharge unit 501 is arranged above the convex mirror 102.

The gas discharge unit 501 is arranged at a position in the negative direction of the Y-axis with respect to the lens barrel 104, and discharges gas through an opening provided in the lens barrel 104. The gas discharge unit 501 includes a connection unit 501a connected to the lens barrel 104, a pipe 501b, and an exhaust mechanism 501c, and the exhaust action of the exhaust mechanism 501c causes the internal space of the lens barrels 103 and 104 to pass through the pipe 501b. The gas is exhausted. By arranging the gas discharge unit 401 not in the Z-axis direction but in the Y-axis direction with respect to the lens barrel 104, it is possible to alleviate the increase in size of the optical device 500 in the Z-axis direction.

In such a configuration, for example, the first optical element 101 and the second optical element 102 are both composed of a lens, and as shown in FIG. 5, from the right side of the optical element 101 toward the left side of the optical element 102. It is suitable when the exposure light L is transmitted.

(Manufacturing method of goods)
The method for manufacturing an article according to the embodiment of the present invention is suitable for producing an article such as a microdevice such as a semiconductor device, an element having a fine structure, or a flat panel display. The method for manufacturing an article of the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate (a step of exposing the substrate) using the above-mentioned exposure apparatus, and a step of forming a latent image pattern in such a step. It includes a process of developing (processing) the substrate. Further, such a manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, flattening, etching, resist peeling, dicing, bonding, packaging, etc.). The method for producing an article of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

(Other Examples)
Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

101 First optical element 102 Second optical element 103, 104 Holding unit 105 Gas supply unit 107 Gas discharge unit

Claims (13)

The first optical element and the second optical element,
A holding portion for holding the first optical element and the second optical element,
A gas supply unit that supplies a temperature-controlled gas toward a flow path provided in the holding unit, and a gas supply unit.
A gas discharge unit that discharges the gas supplied by the gas supply unit,
With
An optical device characterized in that the gas discharge unit is arranged side by side in the arrangement direction of the first optical element and the second optical element. The optical device according to claim 1, wherein the gas discharging unit includes an exhaust mechanism for exhausting gas from a space inside the holding unit. The optical device according to claim 1 or 2, wherein the gas discharging unit is provided outside the optical path incident on the first optical element and the second optical element. Further having a member that separates the internal space and the external space of the holding portion,
The optical device according to any one of claims 1 to 3, wherein the gas discharging unit discharges gas through an opening provided in the member. The holding portion has an opening that communicates the space inside the holding portion with the space outside.
A claim characterized in that, in response to the gas being discharged by the gas discharging portion, the gas is supplied from the space outside the holding portion to the space inside the holding portion through an opening provided in the holding portion. The optical device according to any one of Items 1 to 4. The optical device according to claim 5, wherein the flow rate of the gas discharged by the gas discharge unit is larger than the flow rate of the gas supplied by the gas supply unit. The sixth aspect of claim 6 is characterized in that an amount of gas corresponding to the difference between the flow rate of the gas discharged by the gas discharge unit and the flow rate of the gas supplied by the gas supply unit is supplied from the opening. The optical device described. The gas discharge unit is a gas supplied by the gas supply unit, and is characterized in that the gas that has passed through the space between the first optical element and the second optical element is discharged. The optical device according to any one of 1 to 7. Any one of claims 1 to 8, wherein the first optical element is a lens, and the second optical element is a mirror that reflects light transmitted through the first optical element. The optical device described in. The optical device according to claim 9, wherein the gas discharging unit is arranged on the side opposite to the lens with respect to the mirror. A projection optical system including a first concave reflecting surface, a second concave reflecting surface, and an optical device according to any one of claims 1 to 10.
Projection optics characterized in that light from an object surface is reflected in the order of the first concave reflection surface, the convex reflection surface of the mirror included in the optical device, and the second concave reflection surface to form an image on the image plane. system. An illumination optical system that illuminates the mask with the light from the light source,
The projection optical system according to claim 11, which projects an image of the mask pattern onto a substrate.
An exposure device characterized by having. A forming step of forming a pattern on a substrate by using the exposure apparatus according to claim 12.
Including a processing step of processing the substrate on which a pattern is formed in the forming step.
A method for producing an article, which comprises producing an article from the substrate processed in the processing step.

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