JP2023073020A - Exposure device and method for producing article - Google Patents

Abstract

To provide a technique suitable for correcting aberrations in a projection optical system with high accuracy.SOLUTION: An exposure device performs exposure operation to expose a substrate through a projection optical system. The exposure device comprises a temperature controller that controls a temperature distribution in an optical element included in the projection optical system. The temperature controller is disposed in a circumferential direction of the optical element. When the entire periphery of the optical element in the circumferential direction is defined as T, the temperature controller is disposed in the range of 0.8 T or more and less than T.SELECTED DRAWING: Figure 2

Description

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

2. Description of the Related Art In the manufacture of articles such as semiconductor devices, an exposure apparatus is used that exposes a substrate by illuminating an original (reticle or mask) with an illumination optical system and projecting a pattern of the original onto a substrate via a projection optical system. Since the imaging characteristics of the projection optical system vary depending on exposure light irradiation, the exposure apparatus can correct the imaging characteristics by controlling the attitude and position of the optical element.

Aberration components that can be corrected by controlling the attitude and position of the optical element are limited, and it is difficult to appropriately correct non-rotationally symmetric imaging characteristics such as astigmatism. Japanese Patent Application Laid-Open No. 2002-200003 describes that an adjustment mechanism for adjusting the temperature of an optical member arranged near the pupil plane of the projection optical system changes the temperature distribution of the optical member to adjust the optical characteristics of the projection optical system. It is

Japanese Patent No. 5266641

Patent document 1 focuses on the astigmatism of the projection optical system and discloses adjusting the temperature of the optical member so as to reduce the astigmatism generated by irradiation of the exposure light. There is no description about the possibility of generating aberrations other than astigmatism by adjusting the . Even if the astigmatism of the projection optical system can be properly corrected, there is a possibility that the imaging characteristics of the projection optical system may deteriorate due to the effects of aberrations other than astigmatism.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an advantageous technique for correcting aberrations of a projection optical system with high accuracy.

An exposure apparatus according to the present invention for solving the above-described problems is an exposure apparatus that performs an exposure operation of exposing a substrate via a projection optical system, and includes a temperature adjustment unit that controls the temperature distribution of optical elements included in the projection optical system. wherein the temperature adjustment part is arranged in the circumferential direction of the optical element, and the temperature adjustment part has a range of 0.8 T or more and less than T, where T is the entire circumference of the optical element in the circumferential direction It is characterized in that it is arranged in

According to the present invention, an advantageous technique is provided for correcting the aberration of the projection optical system with high accuracy.

1 is a diagram schematically showing the configuration of an exposure apparatus according to a first embodiment; FIG. It is a figure which shows the structural example of the temperature control part of 1st Embodiment. It is a figure which illustrates the temperature distribution of the lens heated by the temperature control part. It is a figure which shows the relationship between arrangement|positioning of a temperature control part, and aberrations other than astigmatism. It is a figure which shows the structural example of the temperature control part of 2nd Embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In addition, the following embodiments do not limit the invention according to the scope of claims. Although multiple features are described in the embodiments, not all of these multiple features are essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 schematically shows the configuration of the exposure apparatus EXP of the first embodiment. The exposure apparatus EXP generally performs an exposure operation of exposing the substrate 110 via the projection optical system 107 . In the specification and drawings, as shown in FIG. 1, directions are shown in an XYZ coordinate system in which the XY plane is a plane parallel to the plane on which the substrate 110 is arranged. The exposure apparatus EXP has a light source 102 , an illumination optical system 104 , a projection optical system 107 and a controller 100 . In the exposure operation, the illumination optical system 104 illuminates the original 106 with light (exposure light) from the light source 102 , and the projection optical system 107 projects the pattern of the original 106 onto the substrate 110 to expose the substrate 110 . The exposure apparatus EXP may be configured as an exposure apparatus that exposes the substrate 110 while the original 106 and the substrate 110 are stationary, or as an exposure apparatus that exposes the substrate 110 while scanning the original 106 and the substrate 110. may Generally, the substrate 110 has a plurality of shot areas, and an exposure operation can be performed on each shot area.

Light source 102 may include, for example, an excimer laser, but may include other light emitting devices. The excimer laser can generate light with a wavelength of, for example, 248 nm or 193 nm, but may also generate light with other wavelengths. The projection optical system 107 can include an optical element 109 and a temperature controller 108 that controls the temperature distribution of the optical element 109 . The temperature adjustment unit 108 applies heat energy to the optical element 109 to change the refractive index distribution and/or surface shape of the optical element 109, thereby adjusting the optical characteristics (astigmatism) of the projection optical system 107 accompanying the exposure operation. can reduce the change in The thermal energy that the temperature adjuster 108 gives to the optical element 109 can include positive and negative energy. Giving positive energy to the optical element 109 means heating the optical element 109 , and giving negative energy to the optical element 109 means cooling the optical element 109 .

The temperature adjustment section 108 may be placed in close contact with the optical element 109, in which case thermal energy transfer between the temperature adjustment section 108 and the optical element 109 is efficient. Alternatively, the temperature adjustment unit 108 may be spaced apart from the optical element 109. This configuration is advantageous in that the temperature adjustment unit 108 does not apply a mechanical force to the optical element 109, and the temperature adjustment unit This is advantageous in that the optical element 109 is not damaged by the 108, such as scratches.

The temperature adjustment section 108 is preferably arranged outside the effective diameter (optical path) of the optical element 109 so that the temperature adjustment section 108 does not interfere with the irradiation of the substrate 110 with light. For example, the temperature adjustment section 108 can be arranged on the edge of the lens as the optical element 109, or on the front or rear surface of the lens. Alternatively, the temperature adjustment unit 108 may be arranged inside the effective diameter within a range that does not affect the optical performance of the projection optical system 107 . Examples of such an arrangement include, for example, an example in which a thin heating wire is arranged within the effective diameter, and an example in which a heat transfer element having a high light transmittance is arranged within the effective diameter.

When the temperature adjustment unit 108 is arranged on the outer peripheral side of the optical element 109 , the optical element 109 is preferably arranged on or near the pupil plane of the projection optical system 107 . may be spaced apart from the pupil plane of . The temperature control unit 108 includes a first temperature control unit that controls the temperature distribution of the optical element 109 of the projection optical system 107 and a second temperature control unit that controls the temperature distribution of the optical element 109 of the projection optical system 107. temperature control. The plurality of temperature control units (first temperature control unit, second temperature control unit) are individually controlled for the amount and duration of thermal energy applied to the optical element 109, thereby controlling the temperature distribution of the optical element 109. . A plurality of temperature control units (first temperature control unit, second temperature control unit) can be controlled by the control unit 100 . The optical element 109 whose temperature distribution is controlled by the first temperature control section and the optical element 109 whose temperature distribution is controlled by the second temperature control section may be the same or different.

The temperature adjustment unit 108 can change the heat energy given to the optical element 109 in synchronization with the optical characteristics (astigmatism) of the projection optical system 107 that change from moment to moment. Here, the information necessary for controlling the temperature adjustment unit 108 is obtained by measuring the optical characteristics of the projection optical system 107 on the image plane of the projection optical system 107 (the plane on which the substrate 110 is arranged), and based on the result of the measurement. can be generated. Alternatively, the information necessary for controlling the temperature adjustment section 108 may be determined in advance through measurement or the like. For example, when the temperature adjustment unit 108 includes a heating wire, the control of the thermal energy given to the optical element 109 by the temperature adjustment unit 108 can be realized by controlling the current value applied to the heating wire. Alternatively, the control of the thermal energy given to the optical element 109 by the temperature adjuster 108 may be realized by controlling the physical or thermal distance between the optical element 109 and the temperature adjuster 108, for example.

The control unit 100 can control the light source 102 , the illumination optical system 104 , the projection optical system 107 and the temperature adjustment unit 108 . More specifically, the control unit 100 can be configured to control the temperature adjustment unit 108 in addition to controlling the exposure operation. The control unit 100 is, for example, a PLD (abbreviation for Programmable Logic Device) such as FPGA (abbreviation for Field Programmable Gate Array), or ASIC (abbreviation for Application Specific Integrated Circuit), or a general-purpose device in which a program is incorporated. or a dedicated computer, or a combination of all or part of these.

(First embodiment)
FIG. 2 shows a configuration example of the optical element 109 and the temperature adjustment section 108 in the exposure apparatus EXP of the first embodiment. Optical element 109 may include lens 201 . The temperature control unit 108 can include a first temperature control unit 204 composed of heating elements 204a and 204b and a second temperature control unit 203 composed of heating elements 203a and 203b. The heating elements 204 a , 204 b , 203 a , 203 b each have an arc shape and are arranged side by side in the circumferential direction of the lens 201 . The size of each heating element is defined by the opening angle θ with respect to the center of the lens 201 .

The opening angles of the heating elements 204a, 204b, 203a, 203b are θ1, θ2, θ3, θ4, respectively. In this embodiment, the four heating elements are arranged so as to have four-fold symmetry with respect to the center of the lens 201, and θ1=θ2=θ3=θ4. The heating elements 204 a , 204 b , 203 a , 203 b are composed of, for example, flexible cables including heating wires, and heat is generated by applying current to the heating wires to form a temperature distribution on the lens 201 . In this embodiment, the four heating elements are arranged so as to have four-fold symmetry with respect to the center of the lens 201, but strict symmetry is not necessarily required, and the arrangement of the heating elements may be slightly shifted. no problem. Similarly, the size of each heating element may vary slightly.

The heating elements 204a, 204b, 203a, 203b can be arranged, for example, 10-100 μm apart from the plane of the lens 201. FIG. Heat generated by the heating elements 204 a , 204 b , 203 a , 203 b can be transferred to the lens 201 via the medium 205 between the heating elements 204 a , 204 b , 203 a , 203 b and the lens 201 . Medium 205 can be, for example, air or a gas such as nitrogen. Heating elements 204 a , 204 b , 203 a , 203 b need not face lens 201 directly through medium 205 . The heating elements 204a, 204b, 203a, and 203b may have, for example, a structure in which a heating wire is sandwiched between metals having high thermal conductivity.

In the example of FIG. 2B, the heating elements 204a, 204b, 203a, and 203b are arranged on the plane portion of the lens 201 (on the illumination optical system 104 side). However, the heating elements 204 a , 204 b , 203 a , 203 b may be placed under the lens 201 (on the substrate 110 side) or at the edge of the lens 201 . Lens 201 may have a heated surface 206 that is heated by heating elements 204a, 204b, 203a, 203b. The heated surface 206 may be flat or curved. The heated surface 206 can be, for example, a roughened surface (frosted glass surface).

FIG. 3A illustrates the temperature distribution of the lens 201 heated by the second temperature control section 204. FIG. At this time, astigmatism occurs in the positive direction on the surface of the substrate 110 . FIG. 3B illustrates the temperature distribution of the lens 201 heated by the first temperature control section 203. As shown in FIG. The temperature distribution of FIG. 3(b) is a temperature distribution of opposite phase to the temperature distribution of FIG. 3(a). Astigmatism occurs in the negative direction on the surface of the substrate 110 due to the temperature distribution in FIG. 3(b). Thus, the heating of the lens 201 by the first temperature control section 204 and the second temperature control section 203 can generate positive and negative astigmatism. Such a configuration simplifies the configuration of the temperature adjustment section 108 compared to a configuration that uses elements such as Peltier elements to generate positive and negative astigmatism through a combination of heating and cooling. It is advantageous in that it can

Here, heating of the lens 201 can generate a plurality of aberration components other than astigmatism. Among these aberration components, spherical aberration, for example, may degrade the imaging characteristics of the projection optical system 107 . FIG. 4 is a diagram showing the relationship between the opening angle θ of the heating elements in the arrangement of the heating elements shown in FIG. 2 and aberrations other than astigmatism occurring in the projection optical system. FIG. 4A shows the amount of spherical aberration generated, and FIG. 4B shows the amount of four-fold symmetric aberration components generated. A four-fold symmetrical aberration component is a component indicated by a term that has four-fold symmetry when the wavefront aberration of the projection optical system 107 is expanded using Zernike polynomials.

The horizontal axes in FIGS. 4A and 4B indicate the opening angle θ of the heating element, and in this embodiment θ=θ1=θ2=θ3=θ4. As shown in FIGS. 4A and 4B, as the opening angle θ increases, the amount of spherical aberration generated increases, while the amount of four-fold symmetrical aberration components decreases.

The permissible value of the four-fold symmetrical aberration component varies depending on the pattern layout of the master 106, but considering the pattern layout of the master that is generally used, θ is set in the range of 72 degrees or more and less than 90 degrees. is preferred. At this time, the heating element is arranged in a range of 0.8T or more and less than T, where T is the entire circumference of the lens 201 shown in FIG. By arranging the heating elements in this way, it is possible to suppress changes in the astigmatism of the projection optical system 107 due to the exposure operation and to keep aberrations other than the astigmatism of the projection optical system 107 below the allowable value. can.

Regarding the placement of the heating elements, the placement of the heating elements is determined based on the amount of aberration other than astigmatism (for example, spherical aberration and four-fold symmetrical aberration components) in the projection optical system caused by the operation of the temperature adjustment unit 108. By determining, the aberration of the projection optical system can be corrected with high accuracy. As a result, deterioration in imaging characteristics of the projection optical system can be suppressed.

(Second embodiment)
FIG. 5 shows a configuration example of the optical element 109 and the temperature adjustment section 108 in the exposure apparatus EXP of the second embodiment. Optical element 109 may include lens 201 . The temperature adjustment unit 108 can include a first temperature control unit 41 composed of heating elements 411a to 419a and 411b to 419b, and a second temperature control unit 42 composed of heating elements 421a to 429a and 421b to 429b. .

Each heating element has an arc shape and is arranged side by side in the circumferential direction of the lens 201 . The size of each heating element is defined by the opening angle θ with respect to the center of the lens 201 . In this embodiment, θ=10 degrees. In this embodiment, each heating element has the same size, but there is no problem if heating elements with different sizes are arranged.

Each heating element is composed of, for example, a flexible cable including a heating wire, and generates heat by applying an electric current to the heating wire to form a temperature distribution on the lens 201 . The amount and duration of thermal energy imparted to lens 201 by each heating element may be individually controlled, thereby controlling the temperature distribution of lens 201 . A plurality of temperature control units (first temperature control unit, second temperature control unit) can be controlled by the control unit 100 .

For example, the arrangement of the heating elements shown in FIG. A configuration equivalent to that can be realized.

In this embodiment, by appropriately selecting the heating element to which the current is applied, it is possible to obtain the same effect as changing the opening angle in FIG. By appropriately controlling the current applied to each heating element, the change in the astigmatism of the projection optical system 107 accompanying the exposure operation is reduced, and the aberrations other than the astigmatism of the projection optical system 107 are kept below the allowable value. can be suppressed.

(Modification)
As a configuration for applying heat energy to the optical element 109 by the temperature adjustment unit 108, a configuration in which a current is applied to the heating wire forming the temperature adjustment unit 108 has been disclosed, but the configuration is not limited to this. For example, a temperature-controlled gas may be sprayed onto the optical element 109 , or a temperature-controlled liquid may be brought into direct or indirect contact with the optical element 109 . Alternatively, the optical element 109 may be irradiated with infrared rays.

(Product manufacturing method)
Next, an article manufacturing method for manufacturing an article (semiconductor IC element, liquid crystal display element, MEMS, etc.) using the exposure apparatus represented by this embodiment will be described. An article manufacturing method comprises an exposure step of exposing a substrate with the exposure apparatus as described above, a development step of developing the substrate exposed in the exposure step, and a processing step of processing the substrate developed in the development step. and an article can be obtained from the substrate processed in the processing steps. The processing steps can include, for example, etching, resist stripping, dicing, bonding, packaging, and the like. According to the article manufacturing method of the present embodiment, it is possible to manufacture a higher quality article than the conventional one.

107 projection optical system 108 temperature adjustment unit 109 optical element (lens)

Claims (18)

An exposure apparatus that performs an exposure operation of exposing a substrate through a projection optical system,
a temperature adjustment unit that controls the temperature distribution of optical elements included in the projection optical system;
The temperature adjustment unit is arranged in the circumferential direction of the optical element,
The exposure apparatus according to claim 1, wherein the temperature adjustment section is arranged in a range of 0.8 T or more and less than T, where T is the entire circumference of the optical element in the circumferential direction. 2. An exposure apparatus according to claim 1, wherein said temperature adjustment section operates so as to reduce a change in astigmatism of said projection optical system due to said exposure operation. 3. An exposure apparatus according to claim 2, wherein said temperature adjustment unit is arranged so that the amount of aberrations other than said astigmatism generated is equal to or less than an allowable value. 4. An exposure apparatus according to claim 3, wherein said aberration other than astigmatism is spherical aberration. 4. The exposure according to claim 3, wherein the aberration other than the astigmatism is a component represented by a term that has four-fold symmetry when the wavefront aberration of the projection optical system is expanded using Zernike polynomials. Device. 6. The exposure apparatus according to any one of claims 1 to 5, wherein the temperature control section includes a first temperature control section and a second temperature control section arranged at different positions. 7. An exposure apparatus according to claim 6, wherein the temperature distribution given to said optical element by said first temperature control section and the temperature distribution given to said optical element by said second temperature control section are in opposite phases. . 8. The exposure apparatus according to claim 1, wherein the temperature adjustment section is arranged outside an effective diameter of the optical element whose temperature distribution is controlled by the temperature adjustment section. . An exposure apparatus that performs an exposure operation of exposing a substrate through a projection optical system,
A temperature adjustment unit that controls the temperature distribution of optical elements of the projection optical system,
the temperature adjustment unit operates so as to reduce a change in astigmatism of the projection optical system due to the execution of the exposure operation;
The exposure apparatus according to claim 1, wherein the temperature adjustment section is arranged based on an amount of aberration other than astigmatism generated in the projection optical system caused by operation of the temperature adjustment section. 10. An exposure apparatus according to claim 9, wherein said temperature adjustment unit is arranged so that the amount of aberrations other than said astigmatism generated is equal to or less than a permissible value. 11. An exposure apparatus according to claim 10, wherein said aberration other than astigmatism is spherical aberration. 11. The exposure according to claim 10, wherein the aberration other than the astigmatism is a component represented by a term that has four-fold symmetry when the wavefront aberration of the projection optical system is expanded using Zernike polynomials. Device. 13. The exposure apparatus according to any one of claims 9 to 12, wherein the temperature control section includes a first temperature control section and a second temperature control section arranged at different positions. 14. An exposure apparatus according to claim 13, wherein the temperature distribution given to said optical element by said first temperature control section and the temperature distribution given to said optical element by said second temperature control section are in opposite phases. . 15. The exposure apparatus according to any one of claims 9 to 14, wherein the temperature adjustment section is arranged outside an effective diameter of the optical element whose temperature distribution is controlled by the temperature adjustment section. . An exposure apparatus that performs an exposure operation of exposing a substrate through a projection optical system,
a plurality of temperature adjustment units each controlling a temperature distribution of an optical element of the projection optical system and arranged in a circumferential direction of the optical element;
The plurality of temperature adjustment units reduce a change in astigmatism of the projection optical system due to the execution of the exposure operation, and reduce the amount of aberrations other than the astigmatism to an allowable value or less. An exposure apparatus characterized in that it operates with 17. An exposure apparatus according to claim 16, wherein said plurality of temperature adjustment sections are arranged outside an effective diameter of said optical element whose temperature distribution is controlled by said plurality of temperature adjustment sections. A method for manufacturing an article,
an exposure step of exposing a substrate with the exposure apparatus according to any one of claims 1 to 17;
a developing step of developing the substrate exposed in the exposing step;
a processing step of processing the substrate developed in the developing step;
A method for manufacturing an article, characterized in that an article is obtained from the substrate treated in the treatment step.

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