KR20210015654A - Optical apparatus, projection optical system, exposure apparatus and article manufacturing method - Google Patents

Abstract

The present invention provides an optical device which has a gas supply mechanism which reduces a risk that light to an optical element is shaded. The optical device comprises: a first optical element and a second optical element; a holding unit holding the first optical element and the second optical element; a gas supply unit supplying a temperature-controlled gas toward a flow channel installed in the holding unit; and a gas discharge unit discharging the gas supplied by the gas supply unit. The gas discharging unit is disposed along an arranging direction of the first optical element and the second optical element.

Description

Optical device, projection optical system, exposure device and manufacturing method of article {OPTICAL APPARATUS, PROJECTION OPTICAL SYSTEM, EXPOSURE APPARATUS AND ARTICLE MANUFACTURING METHOD}

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

In an optical device using an optical device such as a lens or a mirror, it is known that changes in the temperature of the optical device or a space in an optical path can affect the optical performance of the optical device. This may be caused by 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 factor of the temperature change of the optical device or the space in the optical path as described above, light incident on the optical device may be mentioned. When light passes through an optical device or is reflected by an optical device, some of the light is absorbed by the optical device to generate heat. Part of the generated heat is transferred to the holding unit of the optical element or the space around the optical element. In particular, when there is an optical path close to the holding unit, natural convection may occur as the temperature of the holding unit increases, and heat may be transferred from the holding unit to the space including the optical path. Accordingly, the refractive index of the gas in the optical path changes, which may lead to a decrease in optical performance of the optical device.

In order to suppress a decrease in optical performance in an optical device, a cooling mechanism for cooling an optical element and a space in its vicinity is known. Japanese Patent Application Laid-Open No. 2018-91919 discloses a gas supply mechanism for supplying and discharging gas for temperature control in a space between two optical elements.

In the gas supply mechanism of Japanese Patent Application Laid-Open No. 2018-91919, the gas supply mechanism is arranged in the vertical direction of the two optical elements, so depending on the optical path of light reaching each optical element, the gas supply mechanism is used. There is a fear that the light will be blocked. By studying the arrangement of the gas supply mechanism, it is possible to reduce the risk that light reaching the optical element will be blocked.

It is an exemplary object of the present invention to provide an optical device having a gas supply mechanism in which the risk of blocking light reaching the optical element is reduced.

The optical device of the present invention supplies a temperature-controlled gas toward a flow path provided in the first optical element and the second optical element, the holding portion for holding the first optical element and the second optical element, and the holding portion. And a gas discharging unit for discharging the gas supplied by the gas supply unit, and the gas discharging unit is disposed parallel to the arrangement direction of the first optical element and the second optical element. do.

1 is a schematic diagram showing the overall configuration of an exposure apparatus.
2 is a diagram showing the configuration of an optical device according to the first embodiment.
3 is a view of the optical device viewed in the Y-axis direction.
4 is a diagram showing a configuration of an optical device according to a second embodiment.
5 is a diagram showing the configuration of an optical device according to a third embodiment.
6 is a diagram showing the configuration of an optical device as a comparative example.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In this case, in each of the drawings, the same reference numerals are assigned to the same members, and redundant descriptions are omitted.

1 is a schematic diagram showing the configuration of an exposure apparatus 1 including a projection optical system PO equipped with an optical device of the present invention. The exposure apparatus 1 is used in a photolithography process, which is a manufacturing process of devices such as semiconductor devices and liquid crystal display devices. In the exposure apparatus 1, since the pattern of the mask M is projected onto the photosensitive material on the substrate by using exposure light L having strong light intensity, optical elements such as lenses and mirrors included in the exposure apparatus 1 are exposed. It is easy to become warm by absorbing light L.

The exposure apparatus 1 includes an illumination optical system IL, a projection optical system PO, a mask stage MS that is movable by holding a mask M, and a substrate stage WS that is movable by holding a substrate W. Further, the exposure apparatus 1 includes a control unit C that controls the exposure process to the substrate W, and projects the pattern of the mask M to the resist film (photosensitive agent) on the substrate via the projection optical system PO to form a latent image (latent image pattern). ) Is formed.

Light emitted from a light source (not shown) is shaped by a slit (not shown) included in the illumination optical system IL into, for example, a long arc-shaped light in the X direction. The mask M and the substrate W are held by the mask stage MS and the substrate stage WS, respectively, and are optically disposed at substantially conjugated positions 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 upper surface of the projection optical system PO.

The projection optical system PO projects the pattern formed on the mask M onto the substrate W at a predetermined projection magnification. The pattern formed on the mask M is sequentially transferred onto the substrate W by performing exposure treatment 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 according to the projection magnification of the projection optical system PO. can do.

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 IL2 and transmitted through the mask M has an optical path bent by the first surface G1a of the trapezoidal mirror G1, and enters the first concave reflective surface G2a of the concave mirror G2. The exposure light L reflected from the first concave reflective surface G2a is reflected by the convex reflective surface of the convex mirror G4 after passing through the meniscus lens G3, and is incident on the second concave reflective surface G2b of the concave mirror G2. do. The exposure light L reflected on the second concave reflective surface G2b is bent by the second surface G1b of the trapezoidal mirror G1 to form an image on the substrate W.

In Fig. 1, the concave mirror G2 is a single mirror, and the first concave reflective surface G2a and the second concave reflective surface G2b are the same surface. As another configuration example, the concave mirror G2 may be divided to form a first concave mirror having a first concave reflective surface G2a and a second concave mirror having a second concave reflecting surface G2b.

In the projection optical system PO in FIG. 1, the reflection surface of the convex mirror G4 becomes an optical pupil. Since the optical diameter of the exposure light L decreases in the vicinity of 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 from the convex mirror G4 is increased. Therefore, the meniscus lens G3 and the convex mirror G4 are apt to become warm, and the barrel as a holding part for holding them is apt to become warm.

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

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

(Example 1)

The optical device 100 according to the first embodiment will be described with reference to FIG. 2. The optical device 100 includes a meniscus lens 101 as a first optical element, a convex mirror 102 as a second optical element, a barrel 103 as a holding portion for holding the meniscus lens 101, and a convex surface. It has a barrel 104 as a holding part that holds the mirror 102. In Fig. 2, the barrel 103 and the barrel 104 are configured separately, but the barrel 103 and the barrel 104 may be integrated to form one barrel.

Further, the first optical element is not limited to the meniscus lens 101, and may be a lens of another shape or a mirror. Similarly, the second optical element is not limited to the convex mirror 102, and may be a mirror of any other shape, or may be a lens or the like. In addition, 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 in FIG. 2 shows a specific configuration in the vicinity of the meniscus lens G3 and the convex mirror G4 in FIG. 1. The exposure light L passes through the vicinity of the barrels 103 and 104, and the exposure light L that has passed 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. Again, a pattern that passes through the meniscus lens 101 is displayed.

The optical device 100 includes a gas supply unit 105 for supplying a temperature-controlled gas to the inner spaces of the barrels 103 and 104. The gas supply part 105 supplies gas toward the flow path 106 provided in the barrel 104 as a holding part of the convex mirror 102. That is, the gas supply unit 105 supplies the gas toward 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 inner spaces of the barrels 103 and 104, and as a result, the meniscus lens 101 and the convex mirror 102 are efficiently cooled. can do.

The gas supply unit 105 is disposed 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 disposed 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 for discharging gas from the inner spaces of the barrels 103 and 104. The gas discharge part 107 discharges gas through an opening provided in the plate member 108. The plate member 108 is made of aluminum or the like, and is fixed to the barrel 104. The plate member 108 separates the inner spaces of the barrels 103 and 104 from the outer spaces thereof, and the opening provided in the plate member 108 communicates the inner spaces of the barrels 103 and 104 with the outer spaces. The gas discharge part 107 includes a connecting part 107a connected to the plate-shaped member 108, a pipe 107b, and an exhaust mechanism 107c, and by the exhaust action of the exhaust mechanism 107c, the barrel 103 , Gas is discharged from the inner space of 104 through the pipe 107b.

Fig. 3A is a view of the optical device 100 shown in Fig. 2 viewed from the negative direction of the Y-axis. A plurality of gas supply units 105 are provided with respect to the barrel 104, and temperature-controlled gas is supplied from the gas supply units 105 to the inner spaces of the barrels 103 and 104. At this time, in Fig. 3A, five gas supply units 105 are provided, but 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 member 108. As for the number of gas discharge parts 107, at least one gas discharge part 107 may be provided.

A plurality of protrusions are provided in the barrel 104, and the convex mirror 102 is held by the barrel 104 by pressing the convex mirror 102 against the protrusions. In the region where the protrusion does not exist, a gap is formed between the barrel 104 and the convex mirror 102. This gap functions as a gas flow path.

The gas supplied from the gas supply unit 105 moves through the flow path 106 to the inner spaces of the barrels 103 and 104. In addition, the supplied gas is the space between the meniscus lens 101 and the convex mirror 102 and the gap between the barrel 104 and the convex mirror 102 by the exhaust action of the gas discharge unit 107. After passing through, it is discharged from the opening provided in the plate-shaped member 108 to the external space.

3B is a view of the optical device 100 shown in FIG. 2 viewed in both directions of the Y-axis, and the meniscus lens 101 is not shown. In Fig. 2, three protrusions 110 formed on the surface 103a protrude in both directions of the Y-axis, and the surface 101a provided on the meniscus lens 101 is positioned. The protrusion 111 in FIG. 3B is fixed to the surface 103b of the barrel 103, and the protrusion 111 supports the meniscus lens 101. At this time, a gap is formed between the surface 103a of the barrel 103 and the surface 101a of the meniscus lens 101, and between the surface 103b of the barrel 103 and the surface 101b of the meniscus lens 101, respectively.

Next, as compared with the comparative example, the effect of the optical device 100 of this embodiment will be described. 6 shows an optical device 600 as a comparative example. The same reference numerals are used for the configurations common to the optical device 100 shown in FIG. 2. In Fig. 6, the heat generated by the meniscus lens 101 and the convex mirror 102 due to exposure light L is transmitted to the barrels 103 and 104, and spreads around the barrels 103 and 104 as natural convection. Is shown. In the optical device 600, by providing the cover 601 on the upper portions of the barrels 103 and 104, the diffusion of heat to the surroundings of the barrels 103 and 104 is reduced.

By providing the gas discharge part 602 to the cover 601, the diffusion of heat to the surroundings of the barrels 103 and 104 can be more effectively reduced. The gas discharge part 602 is connected to the exhaust mechanism through a pipe. Gas is discharged from the inner space of the cover 601 by the exhaust function of the exhaust mechanism.

As shown in Fig. 6, by disposing the cover 601 around the barrels 103 and 104, it is possible to reduce the spread of heat to the surroundings of the barrels 103 and 104. However, when space restrictions are provided around the barrels There are many. For example, as shown in Fig. 1, there is a concern that there is an optical path of exposure light L around the barrel, and at least a part of the exposure light L is blocked by arranging the cover 601.

In this embodiment, the gas discharging portion 107 is disposed in the arrangement direction of the optical elements held by the barrels instead of the tops of the barrels 103 and 104. Therefore, exposure light L is not blocked, and an increase in the size of the optical element in the radial direction can be avoided.

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

The gas sucked into the inner space of the barrel 103 moves toward the gas discharge portion 107 through a gap provided between the barrel 103 and the meniscus lens 101. Accordingly, the cooling power of the barrel 103 and the meniscus lens 101 can be enhanced. At this time, it is preferable that the gas in the outer space of the barrel 103 is a gas whose temperature is controlled by a temperature adjustment mechanism not shown. The gas in the outer space of the barrel 103 is preferably a gas controlled to be the same temperature as the temperature of the gas supplied from the gas supply unit 105.

Further, so that the sum of the flow rates of the gases discharged by the respective gas discharge units 107 are greater than the total flow rates of the gases supplied from the respective gas supply units 105, the exhaust force and the The amount of gas supplied to each gas supply unit 105 is controlled. An amount of gas corresponding to the difference between the sum of the flow rates of the gases discharged by the respective gas discharge units 107 and the total flow rates of the gases supplied by the respective gas supply units 105 is transferred from the opening provided in the barrel 103 to the barrel. It is sucked into the inner space of 103.

It has been confirmed by thermal fluid analysis that the temperature rise of the barrels 103 and 104 can be reduced by setting the configuration in which gas is supplied into the barrel from an opening provided in the barrel. In the analysis results of the present inventors, compared with the case where the opening is not provided, the rising temperature can be suppressed to about 5%.

(Example 2)

Next, the configuration of the optical device 400 of the second embodiment will be described with reference to FIG. 4. In the optical device 400 of Example 2, compared with the optical device 100 of Example 1, the number of openings provided in the barrel 103 is increased. Specifically, the opening 115 is also provided in the vertical direction (Z-axis direction) of the barrel 103. Accordingly, since the amount of gas sucked from the outer space of the barrels 103 and 104 to the inner space increases, the cooling power of the barrels 103 and 104, the meniscus lens 101 and the convex mirror 102 can be further strengthened. I can.

(Example 3)

Next, the configuration of the optical device 500 of the third embodiment will be described with reference to FIG. 5. In the optical device 500 of the third embodiment, the arrangement of the gas discharge portion 107 of the optical device 100 of the first embodiment is different. Specifically, the gas discharge portion 501 is disposed above the convex mirror 102.

The gas discharge unit 501 is disposed at a position in the negative Y-axis direction with respect to the barrel 104, and discharges gas through an opening provided in the barrel 104. The gas discharge part 501 includes a connection part 501a connected to the barrel 104, a pipe 501b, and an exhaust mechanism 501c, and by the exhaust action of the exhaust mechanism 501c, the barrels 103 and 104 are Gas is discharged from the inner space through the pipe 501b. By arranging the gas discharge portion 501 in the Y-axis direction rather than the Z-axis direction with respect to the barrel 104, the enlargement of the optical device 500 in the Z-axis direction can be alleviated.

In this configuration, for example, both the meniscus lens 101 as the first optical element and the convex mirror 102 as the second optical element are made of lenses, and as shown in FIG. 5, the first optical element It is suitable for the case where exposure light L is transmitted from the right side of the (meniscus lens 101) toward the left side of the second optical element (lens).

(Product manufacturing method)

The manufacturing method of an article according to an embodiment of the present invention is suitable for manufacturing, for example, a micro device such as a semiconductor device, an element having a microstructure, and an article such as a flat panel display. The manufacturing method of the article of this embodiment includes a step of forming a latent image pattern on the photosensitive agent applied to the substrate W using the above-described exposure apparatus 1 (the step of exposing the substrate W), and the latent image pattern is formed in such a step. It includes a process of developing (processing) the substrate W. In addition, this manufacturing method includes other well-known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The manufacturing method of the 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)

As described above, preferred embodiments of the present invention have been described, but it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

According to the present invention, it is possible to provide an optical device provided with a gas supply mechanism in which the risk of blocking light reaching the optical element is reduced.

Claims (13)

A first optical element and a second optical element,
A holding part for holding the first optical element and the second optical element,
A gas supply unit for supplying a temperature-controlled gas toward a flow path installed in the holding unit,
And a gas discharge unit for discharging the gas supplied by the gas supply unit,
The gas discharge unit is arranged in parallel in the arrangement direction of the first optical element and the second optical element.
The method of claim 1,
And the gas discharge unit includes an exhaust mechanism for exhausting gas from a space inside the holding unit.
The method of claim 1,
And the gas discharge unit is provided outside an optical path incident on the first optical element and the second optical element.
The method of claim 1,
Further comprising a member for separating the space inside and outside the holding part,
And the gas discharge unit discharges gas through an opening provided in the member.
The method of claim 1,
The holding part has an opening communicating the space inside the holding part and the space outside the holding part,
As the gas is discharged by the gas discharge unit, the gas is supplied from the outer space of the holding unit to the inner space through the opening provided in the holding unit.
The method of claim 5,
The optical device, wherein the flow rate of the gas discharged by the gas discharge unit is greater than the flow rate of the gas supplied by the gas supply unit.
The method of claim 6,
An optical device, characterized in that gas in an amount corresponding to a 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 method of claim 1,
The gas discharging unit, as the gas supplied by the gas supply unit, discharges a gas that has passed through the space between the first optical element and the second optical element.
The method of claim 1,
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 method of claim 9,
And the gas discharge unit is disposed on a side opposite to the lens with respect to the mirror.
A projection optical system comprising a first concave reflective surface, a second concave reflective surface, and the optical device according to any one of claims 1 to 10,
A projection optical system, wherein light from an object surface is reflected in the order of the first concave reflective surface, a convex reflective surface of a mirror included in the optical device, and the second concave reflective surface to form an image on the image surface.
An illumination optical system that illuminates the mask with light from a light source,
An exposure apparatus comprising the projection optical system according to claim 11 for projecting the image of the pattern of the mask onto a substrate.
A forming step of forming a pattern on a substrate using the exposure apparatus according to claim 12, and
Including a processing step of processing the substrate on which the pattern is formed in the forming step,
An article manufacturing method, characterized in that the article is manufactured from the substrate processed in the processing step.

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