CN112255886A

CN112255886A - Microenvironment control system of extreme ultraviolet optical element

Info

Publication number: CN112255886A
Application number: CN202010929526.3A
Authority: CN
Inventors: 王魁波; 吴晓斌; 罗艳; 谢婉露; 韩晓泉; 沙鹏飞
Original assignee: Institute of Microelectronics of CAS
Current assignee: Institute of Microelectronics of CAS
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2021-01-22
Anticipated expiration: 2040-09-07
Also published as: CN112255886B

Abstract

The application particularly relates to a microenvironment control system of an extreme ultraviolet optical element, which comprises a vacuum chamber for placing the optical element, a shunt radiator and an air supply device, wherein the shunt radiator is arranged in the vacuum chamber and positioned above the optical element; the split-flow radiator is provided with a light through hole for light to pass through, and the light through hole is not communicated with the cavity; the air supply equipment comprises a high-purity air source, an air supply pipeline and a cooling device, wherein two ends of the air supply pipeline are respectively communicated with the high-purity air source and an air inlet, the cooling device is arranged on the air supply pipeline to reduce the temperature of air in the air supply pipeline, and the extreme ultraviolet optical element microenvironment control system can reduce the temperature of the optical element, prevent the optical element from deforming and reduce pollutant gas around the optical element.

Description

Microenvironment control system of extreme ultraviolet optical element

Technical Field

The application belongs to the technical field of extreme ultraviolet lithography, and particularly relates to a microenvironment control system of an extreme ultraviolet optical element.

Background

This section provides background information related to the present disclosure only and is not necessarily prior art.

Extreme Ultraviolet (EUV) lithography adopts EUV with a wavelength of 13.5nm to perform lithography, and air and almost all refractive optical materials have a strong absorption effect on EUV radiation with a wavelength of 13.5nm, so that the inside of an EUV lithography machine needs to be set to be a clean vacuum environment.

The extreme ultraviolet lithography needs to use a reflective optical element, and because the optical element has higher requirement on temperature, the optical element is easy to absorb heat under the irradiation of extreme ultraviolet light to deform, thereby not only influencing the precision of the lithography process, but also reducing the reflectivity and the service life of the optical element.

Disclosure of Invention

The application provides an extreme ultraviolet optical element's microenvironment control system, including the vacuum chamber that is used for placing optical element to and reposition of redundant personnel radiator and air feeder, reposition of redundant personnel radiator sets up in the vacuum chamber and is located optical element's top, the bottom plate orientation of reposition of redundant personnel radiator optical element's plane of reflection, the inside of reposition of redundant personnel radiator has the cavity, be provided with on the reposition of redundant personnel radiator with air inlet and a plurality of gas outlets of cavity intercommunication, a plurality of the gas outlets set up on the bottom plate; the split-flow radiator is provided with a light through hole for light to pass through, and the light through hole is not communicated with the cavity; the gas supply equipment comprises a high-purity gas source, a gas supply pipeline and a cooling device, wherein two ends of the gas supply pipeline are respectively communicated with the high-purity gas source and the gas inlet, the cooling device is arranged on the gas supply pipeline, and the cooling device is used for reducing the temperature of gas in the gas supply pipeline.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like parts are designated by like reference numerals throughout the drawings. In the drawings:

fig. 1 is a schematic structural diagram of a microenvironment control system of an euv optical element according to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional view of a split radiator in the microenvironment control system of the EUV optical component of FIG. 1;

fig. 3 is a schematic structural diagram of a microenvironment control system of an euv optical element according to another embodiment of the present disclosure.

The reference symbols in the drawings denote the following:

100. a microenvironment control system for the extreme ultraviolet optical element;

10. an optical element; 11. a reflective surface; 12. incident light; 13. reflecting the light;

20. a vacuum chamber;

30. a shunt radiator; 31. a top plate; 311. an air inlet; 32. a base plate; 321. an air outlet; 322. a gas barrier region; 33. a cavity; 34. a light through hole; 35. a side dam;

40. a gas supply device; 41. a high purity gas source; 42. a valve block; 43. a gas flow controller; 44. a throttling element;

50. a low temperature gas stream.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

For convenience of description, spatially relative terms, such as "inner", "outer", "lower", "below", "upper", "above", and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the example term "below … …" can include both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The microenvironment control system 100 of the EUV optical element provided in this embodiment may be applied to an EUV lithography machine, the inside of the EUV lithography machine is a vacuum environment, the EUV lithography machine uses 13.5nm EUV (Extreme Ultra-violet, abbreviated as EUV) light as a working medium, and the optical element may reflect more than 60% of light and absorb about 30% to 40% of incident energy when irradiated by incident EUV light, thereby generating a heating effect.

It should be noted that the optical element 10 may be thermally deformed when heated, and the extreme ultraviolet optical system has very strict requirements on the deformation of the reflection surface 11 of the optical element 10, and is generally only allowed in the nanometer range, so the glass used for manufacturing the optical element 10 generally has a very low thermal expansion coefficient, and at a certain temperature, the thermal expansion coefficient is zero, which is called zero expansion temperature, that is, optimum working temperature, and therefore, in order to prevent the optical element 10 from being deformed, the temperature of the optical element 10 needs to be ensured to be the zero expansion temperature, and in general, the zero expansion temperature is close to 22 ℃.

Accordingly, as shown in fig. 1 to 3, an embodiment of the present application proposes a microenvironment control system 100 for an euv optical element, where the microenvironment control system 100 for an euv optical element includes a vacuum chamber 20 for placing an optical element 10, a shunt radiator 30 and an air supply device 40, where the shunt radiator 30 is disposed in the vacuum chamber 20 and above the optical element 10, a bottom plate 32 of the shunt radiator 30 faces a reflection surface 11 of the optical element 10, a cavity 33 is disposed inside the shunt radiator 30, an air inlet 311 and a plurality of air outlets 321 are disposed on the shunt radiator 30, the air inlet 311 and the plurality of air outlets 321 are communicated with the cavity 33, and the plurality of air outlets 321 are disposed on the bottom plate 32; the shunt radiator 30 is provided with a light through hole 34 for light to pass through, and the light through hole 34 is not communicated with the cavity 33; the gas supply equipment 40 comprises a high-purity gas source 41, a gas supply pipeline and a cooling device, wherein two ends of the gas supply pipeline are respectively communicated with the high-purity gas source 41 and the gas inlet 311, the cooling device is arranged on the gas supply pipeline, and the cooling device is used for reducing the temperature of gas in the gas supply pipeline.

In the microenvironment control system 100 for the euv optical element according to this embodiment, the gas supply device 40 includes a temperature reduction device, the gas output from the high purity gas source 41 is cooled by the temperature reduction device and enters the shunt radiator 30, the shunt radiator 30 is disposed above the optical element 10, and the low temperature gas is released towards the optical element 10 through the gas outlet 321, so as to control the temperature of the reflective surface 11 of the optical element 10, and further prevent the optical element 10 from thermal deformation.

In addition, because the processed material in the photolithography process can release water vapor, hydrocarbon and other pollutant gases, and the water vapor can generate an oxidizing effect on the optical element 10 under the irradiation effect of the extreme ultraviolet light, and the hydrocarbon can form carbon deposition on the surface of the optical element 10, for this reason, the cooling gas blowing and cooling manner of the embodiment can blow the pollutants near the optical element 10 and prevent the pollutants from diffusing to the optical element 10, thereby providing an environment with proper temperature and no pollution for the optical element 10.

Specifically, the shape of the split radiator 30 depends on the structure of the optical element 10 and the propagation path of the light, and may be provided, for example, in a circular ring type, a C-type, or the like; it should be noted that, as shown in fig. 1, the split radiator 30 has a cavity 33 inside for communicating with the gas supply device 40 and flowing the gas supplied from the gas supply device 40 to the optical element 10; in order to ensure the propagation of light and prevent the shunt radiator 30 from blocking the incident light 12 and the reflected light 13 of the optical element 10, the shunt radiator 30 is provided with a light passing hole 34, and the light passing hole 34 is used for providing a path for light to pass through, and it is understood that the cavity 33 is not communicated with the light passing hole 34, for example, when the shunt radiator 30 is shaped as a circular ring or a C-shaped, the light passing hole 34 is formed around the center of the housing constituting the cavity 33.

The shunt radiator 30 is a thin-walled structure, and the housing of the shunt radiator 30 is made of a material with high thermal conductivity and low air release rate, for example, a metal material such as aluminum alloy and stainless steel can be selected, or a material such as ceramic and glass can be selected.

As shown in fig. 2, in some embodiments of the present application, the shunt radiator 30 is configured as a circular ring, that is, a plane parallel to the reflection surface 11 of the optical element 10 is taken as a cross section, the cross section of the shunt radiator 30 is circular ring, a cavity 33 is formed inside the circular ring-shaped housing, and an inner ring of the circular ring-shaped housing is a light-passing hole 34 for passing light.

Specifically, the ring-type divided radiator 30 includes a top plate 31, an inner ring side plate, an outer ring side plate, and a bottom plate 32, wherein the top plate 31 is connected to the inner ring side plate and the outer ring side plate, respectively, and the bottom plate 32 is connected to the inner ring side plate and the outer ring side plate, respectively, as shown in fig. 2, thereby constituting an inner cavity 33. Further, the air inlet 311 for communicating with the air supply apparatus 40 may be provided on the top plate 31, or may be provided on the outer ring side plate, and the air outlet 321 is provided on the bottom plate 32 facing the optical element 10.

In some embodiments of the present application, as shown in fig. 2, the gas inlet 311 is disposed on the top plate 31, and the gas blocking area 322 is disposed on the bottom plate 32 at a position corresponding to the gas inlet 311, it should be noted that a plurality of gas outlets 321 are disposed on the bottom plate 32, and in this embodiment, the gas blocking area 322 refers to an area of the bottom plate 32 where no gas outlet 321 is disposed, that is, all the gas outlets 321 are located outside the gas blocking area 322. In addition, a shielding plate may be attached to the bottom plate 32 at a position corresponding to the gas inlet 311 to block the gas.

It will be understood that the projection of gas inlet 311 onto base 32 falls within gas barrier zone 322, i.e. the area of gas inlet 311 is equal to or less than the area of gas barrier zone 322, whereby gas entering cavity 33 through gas inlet 311 is mostly blocked by gas barrier zone 322, diffuses within cavity 33 and finally exits from gas outlet 321.

In this embodiment, the low-temperature gas entering the cavity 33 exchanges heat with the split-flow radiator 30, so that the bottom plate 32 has a lower temperature, and the low-temperature gas flows out through the gas outlet 321 on the bottom plate 32 during the diffusion process in the cavity 33, and further, the gas outlet 321 is uniformly arranged in the region of the bottom plate 32 except the gas blocking region 322, so that the low-temperature gas flowing out from the gas outlet 321 forms a uniform low-temperature gas flow 50.

On the basis, as shown in fig. 1, since the bottom plate 32 is close to the reflection surface 11 of the optical element 10, and both form a narrow space, the low-temperature air flow 50 will flow to the edge of the optical element 10 and the light through hole 34 of the shunt radiator 30, and the low-temperature air flow 50 in combination with the bottom plate 32 having a lower temperature and a higher emissivity can realize convection cooling and radiation cooling of the optical element 10.

Because the air flow flowing to the optical element 10 has a purging effect, the polluting gases and particles near the optical element 10 can be effectively purged, and the polluting gases and particles are prevented from falling on the reflecting surface 11 of the optical element 10. In addition, the temperature of the reflecting surface 11 of the optical element 10 is higher than that of the bottom plate 32, so that the solid particles between the two move towards the bottom plate 32 under the action of thermophoretic force, thereby further reducing the pollution of the polluting particles to the optical element 10.

Further, the remaining outer surfaces of the shunt radiator 30 except the bottom plate 32 in this embodiment have a low thermal emissivity, reducing heat exchange with the low-temperature gas in the cavity 33, and specifically, in some embodiments of the present application, the outer surfaces of the top plate 31 and the outer ring side plate may be provided with a polished finish or with a low thermal emissivity coating, thereby reducing the thermal emissivity; the bottom plate 32 needs to exchange heat with the low-temperature gas, so that the outer surface of the bottom plate 32 in this embodiment has high thermal emissivity, and specifically, the outer surface of the bottom plate 32 may be provided with a sand blasting surface or a high thermal emissivity coating, thereby increasing the thermal emissivity.

In the present embodiment, the gas supply device 40 is used for supplying a low-temperature gas to the split-flow radiator 30, and specifically, as shown in fig. 1, the gas supply device 40 includes a high-purity gas source 41, a gas supply pipeline and a temperature reduction device, and the high-purity gas source 41 is used for supplying a high-pressure, high-purity, particle-impurity-free working gas which has a small absorption coefficient for EUV light, and may be, for example, nitrogen, helium, hydrogen, argon, dry air or a mixture of the above gases.

High pure air supply 41 communicates with the air supply line, and the heat sink sets up on the air supply line, and the heat sink is arranged in the temperature that reduces the gas in the air supply line, and in some embodiments of this application, the heat sink sets up to throttling element 44, can understand, and the gas of higher pressure passes through throttling element 44 back pressure can drop sharply, and gas temperature can obviously reduce, and the gas that high pure air supply 41 provided is high pressure working gas according to above-mentioned embodiment, and throttling element 44 can make gas temperature reduce fast, has guaranteed cooling rate.

Specifically, the throttling element 44 in this embodiment is a high flow resistance element, such as a capillary tube or a trim valve, and a structure with small holes may be provided on the gas supply pipeline, and the throttling element 44 is used for throttling the gas, so that the gas generates a cooling effect in the throttling process, that is, the temperature of the gas is reduced after passing through the throttling element 44. Further, in the present embodiment, the throttling element 44 is as close as possible to the split radiator 30, and as shown in fig. 1, the throttling element 44 may be disposed within the vacuum chamber 20.

In some embodiments of the present application, the gas supply apparatus 40 further comprises a valve block 42 and a gas flow controller 43, as shown in fig. 1, the valve block 42 and the gas flow controller 43 are disposed on the gas supply line and between the high purity gas source 41 and the temperature reducing device. The valve group 42 is used for controlling the on-off of the air supply pipeline or the pressure of air in the air supply pipeline; the gas flow controller 43 is used to control the flow of gas in the gas supply line.

Specifically, in some embodiments of the present application, the valve set 42 includes a pressure reducing valve and a stop valve, the stop valve can reduce the on-off of the gas in the gas supply pipeline, and the pressure reducing valve can reduce the pressure of the gas in the gas supply pipeline, so as to provide the gas with the proper pressure to the shunt radiator 30 according to the actual requirement; the gas flow controller 43 may be a thermal type flow controller, or may be another type of flow controller.

In some embodiments of the present application, the shunt radiator 30 further includes a side baffle 35, as shown in fig. 3, the side baffle 35 is disposed at the bottom of the shunt radiator 30 along the circumferential direction of the shunt radiator 30, specifically, the side baffle 35 is connected to the edge of the bottom plate 32, taking the case that the shunt radiator 30 is a circular ring type shunt radiator 30 as an example, the side baffle 35 is cylindrical, one end of the side baffle 35 is connected to the bottom plate 32, and the other end faces the reflective surface 11 of the optical element 10.

The side baffle 35 is used to form a relatively sealed space above the optical element 10, so that the most of the uniform low-temperature gas flow 50 released by the shunt radiator 30 flows to the light-passing hole 34 of the shunt radiator 30, and a small part of the gas flows out from the gap between the side baffle 35 and the optical element 10, thereby increasing the heat exchange area between the bottom plate 32 and the optical element 10, and further improving the cooling effect on the optical element 10.

Further, the cross-sectional area of the cylindrical side baffle 35 may be larger than the area of the reflecting surface 11 of the optical element 10, and due to the purging effect of the low-temperature gas flow 50, the external polluting gas and solid particles may be effectively prevented from flowing to the sealed space, thereby further improving the cleanliness of the environment around the optical element 10.

The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A microenvironment control system for euv optical elements, comprising a vacuum chamber for placement of the optical elements, further comprising:

the split-flow radiator is arranged in the vacuum chamber and positioned above the optical element, a bottom plate of the split-flow radiator faces a reflecting surface of the optical element, a cavity is formed in the split-flow radiator, an air inlet and a plurality of air outlets which are communicated with the cavity are formed in the split-flow radiator, and the plurality of air outlets are formed in the bottom plate; the split-flow radiator is provided with a light through hole for light to pass through, and the light through hole is not communicated with the cavity;

air supply equipment, air supply equipment includes high pure air supply, air supply line and heat sink, the both ends of air supply line respectively with high pure air supply with the air inlet intercommunication, the heat sink sets up on the air supply line, the heat sink is used for reducing the temperature of the gas in the air supply line.

2. The system of claim 1, wherein the split radiator has a circular or C-shaped cross-section in a plane parallel to the reflective surface of the optical element.

3. The system of claim 2, wherein the split-flow radiator comprises a top plate, an inner ring side plate, an outer ring side plate, and a bottom plate, the top plate is connected to the inner ring side plate and the outer ring side plate, the bottom plate is connected to the inner ring side plate and the outer ring side plate, and the air inlet is disposed on the top plate.

4. The system of claim 3, wherein the outer surfaces of the top plate and the outer ring side plate are provided with a polished finish or with a low thermal emissivity coating.

5. The system of claim 3, wherein the outer surface of the base plate is provided with a sand blasting surface or a high thermal emissivity coating.

6. The system of claim 1, wherein the base plate is provided with a gas barrier region, a projection of the gas inlet onto the base plate falls within the gas barrier region, and the plurality of gas outlets are located outside the gas barrier region.

7. The system of claim 1, wherein the gas supply apparatus further comprises a valve block and a gas flow controller, the valve block and the gas flow controller being disposed on the gas supply line and between the high purity gas source and the temperature reduction device.

8. The system of claim 7, wherein the valve block comprises a pressure relief valve and a shut-off valve.

9. The system of claim 1, wherein the cooling device is configured as a throttling element.

10. The euv optical element microenvironment control system of any one of claims 1 to 9, wherein the shunt radiator further comprises a side baffle disposed at a bottom of the shunt radiator in a circumferential direction of the shunt radiator.