Exposure method, exposure apparatus, and article manufacturing method

Abstract

To provide a technique advantageous in suppressing an overcorrection phenomenon of exposure astigmatism.SOLUTION: An exposure method of exposing a substrate includes an adjustment step of irradiating an optical element included in a projection optical system with light in a state in which at least part of a light beam is shielded by a shielding member to adjust an optical characteristic of the projection optical system, a heat dissipation step of dissipating heat accumulated in the shielding member by the adjustment step, and an exposure step of exposing the substrate via the projection optical system after the heat dissipation step. In the heat dissipation step, heat is dissipated at a heat dissipation amount from the shield based on at least one of the light irradiation condition in the adjustment step and the exposure condition in the exposure step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exposure method, an exposure apparatus, and an article manufacturing method. [Background technology]

[0002] In the manufacture of semiconductor devices and other products, exposure apparatuses are used to illuminate an original (reticle or mask) with an illumination optical system and project the original pattern onto a substrate via a projection optical system, thereby exposing the substrate. Because the imaging characteristics of the projection optical system fluctuate depending on the exposure light, exposure apparatuses correct these imaging characteristics by controlling the position and orientation of optical elements. However, the aberration components that can be corrected by controlling the position and orientation of optical elements are limited, and correcting non-rotationally symmetric imaging characteristics such as astigmatism is difficult. In particular, scanning exposure apparatuses (scanners) use a rectangular slit, which generates a non-rotationally symmetric heat distribution in the projection optical system during exposure, resulting in non-rotationally symmetric exposure aberrations (hereinafter referred to as "exposure astigmatism"). Furthermore, repeated exposures using an original containing many patterns in a specific direction can also result in significant exposure astigmatism.

[0003] Patent Document 1 discloses performing a dummy exposure to correct exposure astigmatism that occurs during actual exposure. When performing a dummy exposure, a light-shielding object in the projection optical system is used to block light from reaching the image plane. This is done to prevent the stage on which the substrate is mounted from expanding due to exposure heat, which could affect exposure accuracy, and to prevent the resist applied to the substrate from being exposed to light. Furthermore, when light hits the light-shielding object, the object accumulates heat, which warms the nearby lens. Therefore, by placing such a light-shielding object, the correction efficiency of exposure astigmatism can be improved.

[0004] On the other hand, if heat remains in the light shielding material when switching to pattern exposure, when pattern exposure is performed with part of the light blocked by the shielding material, the residual heat will continue to cause aberrations, resulting in overcorrection. As disclosed in Patent Document 2, heat from the NA stop can be dissipated by radiation by adjusting the aperture shape. Another possible way to suppress overcorrection is to bring the light shielding material into contact with a low-temperature material to dissipate heat by heat transfer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-185871 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-044560 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if heat is dissipated by heat transfer, depending on the exposure conditions and the time of the dummy exposure, heat dissipation may be insufficient, resulting in the overcorrection phenomenon.

[0007] The present invention provides a technique that is advantageous in suppressing the phenomenon of overcorrection of exposure astigmatism. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided an exposure method for exposing a substrate, comprising: an adjustment step of irradiating light onto an optical element included in a projection optical system while blocking at least a portion of the light beam with a shield in order to adjust the optical characteristics of the projection optical system; a heat dissipation step of releasing heat accumulated in the shield by the adjustment step; and an exposure step of exposing the substrate via the projection optical system after the heat dissipation step, wherein in the heat dissipation step, heat is dissipated from the shield at an amount based on at least one of the light irradiation conditions in the adjustment step and the exposure conditions in the exposure step. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a technique that is advantageous in suppressing the phenomenon of overcorrection of exposure astigmatism. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of an exposure apparatus. [Figure 2] 10 is a flowchart showing an exposure method. [Figure 3] FIG. 10 is a diagram showing a rotationally asymmetric effective light source distribution used for dummy exposure. [Figure 4] 10A and 10B are diagrams showing non-rotationally symmetric wavefront aberrations that occur in a projection optical system due to dummy exposure. [Figure 5] 10 is a flowchart showing a heat dissipation process. [Figure 6] Graph showing temperature change characteristics when the NA aperture is fully open. [Figure 7] 10A and 10B are diagrams for explaining the operation of the NA diaphragm in the adjustment process and the heat dissipation process. [Figure 8] FIG. 10 is a cross-sectional view of a main part of an NA diaphragm according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] FIG. 1 is a diagram showing the configuration of an exposure apparatus in an embodiment. In this specification and drawings, directions are indicated in an XYZ coordinate system in which the horizontal plane is the XY plane. A substrate 115, which is an object to be exposed, is placed on a substrate stage 102 so that its surface is parallel to the horizontal plane (XY plane). Therefore, in the following, the directions that are perpendicular to each other in a plane along the substrate placement surface of the substrate stage 102 are referred to as the X-axis and Y-axis, and the direction perpendicular to the X-axis and Y-axis is referred to as the Z-axis. Furthermore, in the following, the directions that are parallel to the X-axis, Y-axis, and Z-axis in the XYZ coordinate system are referred to as the X-direction, Y-direction, and Z-direction, respectively, and the directions of rotation around the X-axis, Y-axis, and Z-axis are referred to as the θX-direction, θY-direction, and θZ-direction, respectively.

[0013] 1 is a diagram showing the schematic configuration of an exposure apparatus according to this embodiment. The exposure apparatus is configured to irradiate an original (also called a mask or reticle) 109 with light emitted from a light source 1 through an illumination optical system 104, and to project the pattern of the original onto a substrate 115 via a projection optical system 110, thereby exposing the substrate 115.

[0014] The illumination optical system 104 is composed of elements arranged in the optical path from the light source 1 to the original 109. The light source 1 can be, for example, an ArF excimer laser with an oscillation wavelength of approximately 193 nm or a KrF excimer laser with an oscillation wavelength of approximately 248 nm, but the present invention is not limited to a specific type of light source or wavelength of light.

[0015] Light emitted from a light source 1 enters an illumination system 104 and is guided to a diffractive optical element 3 by a deflection optical system 2. Typically, a diffractive optical element is mounted in each slot of a turret having multiple slots, and a drive mechanism 107 can position any diffractive optical element (for example, diffractive optical element 4) in the optical path.

[0016] The light emitted from the diffractive optical element 3 is condensed by the condenser lens 5, and forms a diffraction pattern on the diffraction pattern surface 6. The shape of the diffraction pattern can be changed by replacing the diffractive optical element 3 positioned in the optical path using the drive mechanism 107.

[0017] The diffraction pattern formed on the diffraction pattern surface 6 is incident on a mirror 9 after parameters such as the annular ratio and σ value are adjusted by a prism group 7 and a zoom lens 8. The light beam reflected by the mirror 9 is incident on an optical integrator 10. The optical integrator 10 may be configured, for example, as a lens array (fly's eye). The prism group 7 includes, for example, a prism 7a and a prism 7b. If the distance between the prisms 7a and 7b is sufficiently small, the prisms 7a and 7b can be regarded as a single, integrated glass plate. By changing the distance between the prisms 7a and 7b, the annular ratio (ratio of the outer diameter to the inner diameter) and other parameters can be appropriately changed, thereby changing the light intensity distribution.

[0018] The diffraction pattern formed on the diffraction pattern surface 6 can be enlarged or reduced by the zoom lens 8 while maintaining a substantially similar shape, as shown in FIG. 3. Light transmitted through the zoom lens 8 is imaged on the incident surface of the optical integrator 10. The optical integrator 10 is configured by arranging a plurality of microlenses two-dimensionally, and the light beam incident on the optical integrator 10 is split, and a light source is formed on the back focal plane of each microlens. In this way, a substantial surface light source (secondary light source) having a light intensity distribution substantially the same as that of the incident light beam is formed on the back focal plane of the optical integrator 10.

[0019] The light beam emitted from the optical integrator 10 has its light intensity distribution adjusted by the aperture stop 12 and is condensed by the condenser lens 11 to superimpose and illuminate a field stop 13 positioned conjugate to the original 109. The field stop 13 defines the illumination area of ​​the original 109 (and further the substrate 115) by the exposure light. The aperture shape of the aperture stop 12 can be set to any shape by driving a light-shielding plate that forms the aperture stop 12 with a driving mechanism 106. The numerical aperture NA of the illumination optical system 104 can be controlled by changing the aperture diameter of the aperture stop 12 with the driving mechanism 106. In other words, by changing the aperture diameter of the aperture stop 12, it is possible to control the σ value (coherence factor), which is the ratio of the numerical aperture NA of the illumination optical system 104 to the numerical aperture NA of the projection optical system 110.

[0020] The light beam that passes through the aperture of the field stop 13 passes through the imaging optical system 15 and illuminates the original 109 held by the original stage 101. A correction filter 14 is disposed between the imaging optical system 15 and the original 109. This correction filter adjusts the optical characteristics of the light irradiating the original 109. The projection optical system 110 projects the pattern of the original 109 onto a substrate 115 held by the substrate stage 102 at a predetermined magnification (for example, 1 / 4 magnification). This forms a pattern in the photosensitive agent on the substrate 115.

[0021] The exposure apparatus is configured to perform pattern exposure by blocking part of the light with a shield. The shield can be the blades of an aperture stop arranged inside the projection optical system 110. For example, an aperture stop (hereinafter referred to as an "NA stop") 111 with a substantially circular opening is arranged on or near the pupil plane of the projection optical system 110, and the size of the opening is controlled by a drive mechanism 112. The projection optical system 110 also has a drive mechanism 113 that changes the aberration of the projection optical system 110 by moving, rotating, and / or deforming at least one of the multiple lenses that make up the projection optical system 110. The drive mechanism 113 can include, for example, a mechanism that moves the lens in a direction along the optical axis (Z-axis) of the projection optical system 110 or two axes (X-axis and Y-axis) perpendicular to the optical axis, and a mechanism that rotates the lens around axes parallel to the two axes (X-axis and Y-axis) perpendicular to the optical axis.

[0022] The substrate stage 102 is movable in the X, Y, and Z directions. The substrate stage 102 is driven by a driving mechanism 116. The driving mechanism 116 is controlled by a stage control unit 117. In the case of a scanning exposure apparatus, during exposure operation, the original stage 101 and the substrate stage 102 are driven synchronously in the Y direction to perform scanning exposure.

[0023] The main control unit 103 comprehensively controls the illumination system control unit 108, projection system control unit 114, stage control unit 117, etc. The main control unit 103 includes a memory for storing programs and data, and performs exposure operations by executing control programs stored in the memory. The main control unit 103 can be configured, for example, by a PLD (abbreviation for Programmable Logic Device) such as an FPGA (abbreviation for Field Programmable Gate Array), an ASIC (abbreviation for Application Specific Integrated Circuit), a general-purpose computer with an embedded program, or a combination of all or part of these.

[0024] Next, the exposure method according to this embodiment will be described with reference to the flowchart in Fig. 2. The following steps are executed by the main control unit 103.

[0025] Before starting an exposure job, in S1, the main controller 103 measures the astigmatism of the projection optical system 110. An "exposure job" refers to, for example, a job related to a series of exposures in one lot (e.g., 25 substrates). The astigmatism is measured, for example, by the measurement system controller 119 controlling the measurement sensor 118 arranged on the substrate stage 102.

[0026] In S2, the main controller 103 determines whether the astigmatism obtained by the measurement in S1 exceeds a threshold value. If the astigmatism does not exceed the threshold value, the process proceeds to an exposure step S5 in which the substrate 115 is exposed via the projection optical system 110. If the astigmatism exceeds the threshold value, the process proceeds to S3. S3 is an adjustment step in which light irradiation (hereinafter referred to as "dummy exposure") is performed to irradiate the projection optical system 110 with light to reduce aberrations occurring in the projection optical system 110.

[0027] The dummy exposure performed in S3 will now be described. Light emitted from the light source 1 forms an effective light source distribution as shown in FIG. 3(a) or 3(b) through the diffractive optical element 3 in the illumination optical system 104. The "effective light source distribution" refers to the light intensity distribution in the pupil plane of the illumination optical system 104 that illuminates the original 109. The dashed lines in FIGS. 3(a) and 3(b) represent σ=1, with white areas having light intensity. The light of the generated effective light source distribution reaches the original stage 101 via the illumination optical system 104. At this time, the light emitted from the illumination optical system 104 directly enters the projection optical system 110 without passing through the original 109 on the original stage 101. At this time, the original 109 may be removed from the original stage 101, or the original stage 101 carrying the original 109 may be driven to retract from the optical path.

[0028] Light entering the projection optical system 110 is irradiated onto an NA diaphragm 111 located on or near the pupil plane within the projection optical system 110. The size of the aperture of the NA diaphragm 111 is controlled by a drive mechanism 112 to prevent light from reaching the substrate 115. When the light enters the lens group constituting the projection optical system 110, the lenses are heated by absorption in the lens glass and anti-reflection coating, causing a change in the refractive index of the lenses and generating wavefront aberration. Furthermore, heat is accumulated in the blades of the NA diaphragm 111 that are hit by the light, warming nearby lenses and potentially further increasing the amount of wavefront aberration. For example, if an effective light source distribution such as that shown in FIG. 3(a) is generated by the diffractive optical element 3 and light is incident on the projection optical system 110, the wavefront aberration of the projection optical system 110, which is generated by absorption in the lens glass and anti-reflection coating, becomes astigmatism as shown in FIG. 4.

[0029] As described above, in the adjustment step S3, a dummy exposure is performed in which light is irradiated onto the optical elements included in the projection optical system 110 while at least a portion of the light beam is blocked by the blades of the NA diaphragm 111, which serves as a shield, in order to adjust the optical characteristics of the projection optical system 110. By performing such a dummy exposure, it is possible to reduce exposure astigmatism caused by the rectangular slit of the scanner and non-rotationally symmetric exposure astigmatism that occurs when performing successive exposures using an original that includes many patterns in a specific direction.

[0030] After the adjustment step S3 is completed, in S4, the main control unit 103 performs a heat dissipation step to dissipate heat accumulated in the blades of the NA diaphragm 111, which serves as a shield. The operation of the NA diaphragm 111 in the adjustment and heat dissipation steps will be described with reference to FIG. 7. In FIG. 7, (a1) and (b1) are plan views of the NA diaphragm as seen from the -Z direction, and (a2) and (b2) are cross-sectional views along the A-A' line in (a1) and (b1). During dummy exposure, the NA diaphragm 111 is closed as shown in FIG. 7(a1) so that light does not reach the substrate 115. In the heat dissipation step, the NA diaphragm 111 is controlled by the drive mechanism 112 to be fully open as shown in FIG. 7(b1). In the open state, the blades 121 of the NA diaphragm 111 are stored in the storage base 120 (storage unit). At this time, the heat that had accumulated in a part of the blades 121 of the NA diaphragm 111 (the dashed line part in Figure 7(a2)), which had become hot due to the irradiated light energy, moves to the storage base 120, thereby cooling the blades 121 of the NA diaphragm 111.

[0031] After the heat dissipation step S4 is completed, the exposure step S5 is carried out. In the exposure step, an exposure operation is performed to form a pattern on the photosensitive agent on the substrate 115. At this time, the size of the opening of the NA diaphragm 111 is controlled by the drive mechanism 112 to create illumination conditions suitable for the pattern to be exposed. If the illumination conditions are particularly small NA illumination conditions, the blades of the NA diaphragm 111, which have remained heated, are largely exposed from the storage base 120 and heat up the nearby lenses, causing overcorrection of wavefront aberration.

[0032] The heat dissipation step S4 for preventing overcorrection of wavefront aberration will be described with reference to the flowchart of Fig. 5. The heat dissipation step S4 may include a determination step for determining the amount of heat dissipation from the blades 121 of the NA stop 111 based on the light irradiation conditions in the adjustment step S3 and the exposure conditions in the exposure step S5. In this embodiment, as shown in Fig. 5, the determination step may include the following steps S41 to S43.

[0033] In S41, the main control unit 103 obtains the temperature change of the blades 121 of the NA aperture 111 in the adjustment step S3 based on the light irradiation conditions in the adjustment step S3 (the first step). In this S41, for example, the main control unit 103 obtains the energy of the light (light energy) irradiated in the adjustment step S3 (dummy exposure) based on the irradiation time and illuminance, which are the light irradiation conditions. Let the irradiation time of the light for dummy exposure be t [s] and the illuminance be L [W / m 2 , then the light energy E [J / m 2 is obtained by the following formula.

[0034] E [J / m 2 = t [s] × L [W / m 2 Next, the main control unit 103 obtains the temperature change of the NA aperture 111 based on the obtained light energy. Specifically, it obtains the temperature change ΔT [°C] of the NA aperture 111 when the obtained light energy is irradiated on the NA aperture 111 during dummy exposure. Let the length of the blade 121 exposed in the optical path from the storage base 120 during dummy exposure be th_0 [m], and the thermal conductivity according to the material of the NA aperture 111 be k [W / (m·K)]. Then, the temperature change ΔT [°C] of the NA aperture 111 is obtained by the following formula.

[0035] ΔT [°C] = E [J / m 2 / -k [W / (m·K)] × th_0 [m] In S42, the main control unit 103 obtains the aberration of the projection optical system 110 based on the temperature change obtained in S41 (the second step). Here, let the exposed length of the blade 121 of the NA aperture 111 be th_1 [m] (0 ≤ th_1 < th_0). When the temperature change of the blade 121 of the NA aperture 111 from T [°C] is ΔT [°C], the generated aberration ΔW [mλ] by the nearby lens is represented by the following formula.

[0036] ΔW [mλ] = ΔT [°C] × α (th_1 / th_0) However, α is a constant calculated as the air thermal conductivity [W / (m·K)] / the distance between the blade and the lens [m] / the lens thermal conductivity [W / (m·K)] × the lens deformation sensitivity [nm / °C] × the lens aberration sensitivity [mλ / nm]. ​

[0037] In S43, the main control unit 103 determines the amount of heat dissipation so that the aberration calculated in S42 is smaller than the aberration tolerance determined depending on the exposure conditions in the exposure step S5 (third step). The amount of heat dissipation of the NA stop 111 is calculated based on the threshold value AS [mλ]. The threshold value AS [mλ] corresponds to the tolerance of astigmatism (aberration tolerance). To prevent overcorrection, it is sufficient that the aberration caused by this nearby lens is smaller than the threshold value AS [mλ] (aberration tolerance). That is, ΔT [℃] × α = ΔW [mλ] <AS[mλ] From this, the amount of heat dissipation, i.e., the required temperature change ΔT [℃] can be calculated.

[0038] The threshold value AS [mλ] is determined depending on the exposure conditions used in the exposure step S5. For example, if the numerical aperture (exposure NA) of the projection optical system, which is one of the exposure conditions, differs, the lens aberration sensitivity [mλ / nm] also changes, so even with the same amount of surface deformation, the generated aberration differs and the required temperature change ΔT [°C] changes. Furthermore, if the exposure NA differs, the exposed length th_1 of the blades 121 of the NA stop 111, which is still heated, changes, so the required temperature change ΔT [°C] also changes. Furthermore, when the exposure condition is the NA stop fully open (exposed length th_1 of the blades 121 = 0), ΔW [mλ] = 0, and it is not necessary to perform the heat dissipation step.

[0039] In S44, the main control unit 103 performs heat dissipation by fully opening the NA diaphragm 111 using the drive mechanism 112 for the time (heat dissipation time) required to achieve the required temperature change (ΔT [°C]) determined in S43. For example, the amount of change in temperature of the blades 121 of the NA diaphragm 111 over time (heat dissipation time) when the NA diaphragm 111 is fully opened after the dummy exposure can be determined by simulation. FIG. 6 is a graph showing an example of the characteristics of the change in temperature of the blade tips of the NA diaphragm 111 over time determined by simulation. In this case, the main control unit 103 can determine the heat dissipation time based on the characteristics of the change in temperature of the blades 121 of the NA diaphragm 111 over time determined by simulation. Therefore, in this case, the main control unit 103 determines the time required to achieve the required temperature change (ΔT [°C]) determined in S43 based on the characteristics shown in FIG. 6. 6 may be obtained not by simulation but by actually measuring the amount of change in temperature of the NA diaphragm 111 over time when the NA diaphragm 111 is heated alone and fully opened before assembling the device. In this case, the main control unit 103 determines the heat dissipation time based on the results of actually measuring the amount of change in temperature of the blades 121 of the NA diaphragm 111 over time.

[0040] 5 described above, the amount of heat dissipation from the blades 121 of the NA stop 111 is determined based on both the light irradiation conditions in the adjustment step S3 and the exposure conditions in the exposure step S5. However, in the heat dissipation step S4, the amount of heat dissipation from the blades 121 of the NA stop 111 may be determined based on either the light irradiation conditions in the adjustment step S3 or the exposure conditions in the exposure step S5. That is, in the heat dissipation step S4, the amount of heat dissipation from the blades 121 of the NA stop 111 may be determined based on at least one of the light irradiation conditions in the adjustment step S3 and the exposure conditions in the exposure step S5.

[0041] As described above, by controlling the heat radiation time of the NA diaphragm 1110, it is possible to prevent the phenomenon of overcorrection of wavefront aberration (astigmatism) from occurring.

[0042] 8 is a cross-sectional view of a main part of an NA diaphragm 111 according to a modified example. In this modified example, a gap 122 is provided in a storage base 120 of the NA diaphragm 111. By circulating air or liquid through this gap 122, the storage base 120 and the blades 121 arranged thereon are air-cooled or liquid-cooled. This improves the cooling efficiency of the blades 121 and shortens the heat dissipation time.

[0043] <Embodiment of an article manufacturing method> The article manufacturing method according to an embodiment of the present invention is suitable for manufacturing articles such as microdevices, such as semiconductor devices, and elements having microstructures. The article manufacturing method according to this embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the exposure apparatus described above according to the exposure method described above (an exposure step of exposing the substrate), and a development step of developing the substrate on which the latent image pattern has been formed. Furthermore, this manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method according to this embodiment is advantageous over conventional methods in at least one of article performance, quality, productivity, and production cost.

[0044] The disclosure of the present specification includes at least the following techniques. (Item 1) An exposure method for exposing a substrate, comprising: an adjusting step of irradiating light onto an optical element included in the projection optical system in a state where at least a part of the light beam is blocked by a shielding member in order to adjust the optical characteristics of the projection optical system; a heat dissipation step of dissipating heat accumulated in the shield by the adjustment step; an exposure step of exposing the substrate via the projection optical system after the heat dissipation step, an exposure method, wherein in the heat dissipation step, heat is dissipated from the shield at an amount based on at least one of the light irradiation conditions in the adjustment step and the exposure conditions in the exposure step. (Item 2) 2. The exposure method according to item 1, wherein in the heat dissipation step, heat is dissipated from the shield at an amount based on the light irradiation conditions in the adjustment step and the exposure conditions in the exposure step. (Item 3) The heat dissipation step includes: a first step of determining a temperature change of the shield in the adjusting step based on the light irradiation conditions; a second step of determining the aberration of the projection optical system based on the temperature change; a third step of determining the amount of heat dissipation so that the aberration is smaller than an aberration tolerance determined depending on the exposure conditions; 3. The exposure method according to item 2, comprising: (Item 4) the light irradiation conditions include light irradiation time and illuminance, In the first step, the energy of the light irradiated in the adjusting step is calculated based on the irradiation time and the illuminance, and the temperature change is calculated based on the energy. 4. The exposure method according to item 3, (Item 5) 5. The exposure method according to item 3 or 4, wherein the exposure conditions include the numerical aperture of the projection optical system. (Item 6) 6. The exposure method according to any one of items 1 to 5, wherein the shielding object is a blade of an aperture stop arranged inside the projection optical system. (Item 7) 7. The exposure method according to item 6, wherein the aperture stop is an NA stop arranged on or near the pupil plane of the projection optical system. (Item 8) the aperture stop includes a storage portion that stores the blades in an open state, In the heat dissipation step, the aperture stop is opened to transfer heat from the blades to the housing, thereby dissipating heat from the shield. 8. The exposure method according to item 6 or 7, (Item 9) 9. The exposure method according to any one of items 1 to 8, wherein the amount of heat dissipation in the heat dissipation step is controlled by the heat dissipation time of the shield. (Item 10) 10. The exposure method according to item 9, wherein the heat radiation time is determined based on a characteristic of the change in temperature of the shield with respect to the elapsed time, the characteristic being obtained by simulation. (Item 11) 10. The exposure method according to item 9, wherein the heat radiation time is determined based on the result of actually measuring the amount of change in the temperature of the shield over time. (Item 12) 12. The exposure method according to any one of items 1 to 11, wherein the adjusting step is performed in a state where the shielding member prevents light from reaching the substrate. (Item 13) An exposure apparatus for exposing a substrate, a projection optical system; a shield disposed inside the projection optical system; a control unit, The control unit an adjusting step of irradiating light onto an optical element included in the projection optical system while blocking at least a part of the light beam with the blocking member in order to adjust the optical characteristics of the projection optical system; a heat dissipation step of dissipating heat accumulated in the shield by the adjustment step; an exposure step of exposing the substrate via the projection optical system after the heat dissipation step; configured to: the control unit is further configured to determine the amount of heat dissipation from the shield in the heat dissipation step based on at least one of light irradiation conditions in the adjustment step and exposure conditions in the exposure step. (Item 14) an exposure step of exposing a substrate according to the exposure method according to any one of items 1 to 12; a developing step of developing the exposed substrate; and manufacturing an article from the developed substrate.

[0045] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0046] 101: original stage, 102: substrate stage, 103: main control unit, 104: illumination optical system, 109: original, 110: projection optical system, 111: NA aperture, 115: substrate

Claims

1. An exposure method for exposing a substrate, comprising: an adjusting step of irradiating light onto an optical element included in the projection optical system in a state where at least a part of the light beam is blocked by a shielding member in order to adjust the optical characteristics of the projection optical system; a heat dissipation step of dissipating heat accumulated in the shield by the adjustment step; an exposure step of exposing the substrate via the projection optical system after the heat dissipation step, an exposure method, wherein in the heat dissipation step, heat is dissipated from the shield at an amount based on at least one of the light irradiation conditions in the adjustment step and the exposure conditions in the exposure step.

2. 2. The exposure method according to claim 1, wherein in the heat dissipation step, heat is dissipated from the shield at an amount based on light irradiation conditions in the adjustment step and exposure conditions in the exposure step.

3. The heat dissipation step includes: a first step of determining a temperature change of the shield in the adjusting step based on the light irradiation conditions; a second step of determining the aberration of the projection optical system based on the temperature change; a third step of determining the amount of heat dissipation so that the aberration is smaller than an aberration tolerance determined depending on the exposure conditions; 3. The exposure method according to claim 2, further comprising:

4. the light irradiation conditions include light irradiation time and illuminance, In the first step, the energy of the light irradiated in the adjusting step is calculated based on the irradiation time and the illuminance, and the temperature change is calculated based on the energy.

4. The exposure method according to claim 3.

5. 4. The exposure method according to claim 3, wherein the exposure conditions include a numerical aperture of the projection optical system.

6. 2. The exposure method according to claim 1, wherein the shielding object is a blade of an aperture stop arranged inside the projection optical system.

7. 7. An exposure method according to claim 6, wherein the aperture stop is an NA stop arranged on or near a pupil plane of the projection optical system.

8. the aperture stop includes a storage portion that stores the blades in an open state, In the heat dissipation step, the aperture stop is opened to transfer heat from the blades to the housing, thereby dissipating heat from the shield.

7. The exposure method according to claim 6.

9. 2. The exposure method according to claim 1, wherein the amount of heat dissipated in the heat dissipation step is controlled by a heat dissipation time of the shield.

10. 10. The exposure method according to claim 9, wherein the heat radiation time is determined based on a characteristic of a change in temperature of the shield with respect to elapsed time, the change being obtained by simulation.

11. 10. The exposure method according to claim 9, wherein the heat radiation time is determined based on a result obtained by actually measuring a change in temperature of the shield with respect to an elapsed time.

12. 2. The exposure method according to claim 1, wherein the adjusting step is performed in a state where light is prevented from reaching the substrate by the shielding member.

13. An exposure apparatus for exposing a substrate, a projection optical system; a shield disposed inside the projection optical system; a control unit, The control unit an adjusting step of irradiating light onto an optical element included in the projection optical system while blocking at least a part of the light beam with the blocking member in order to adjust the optical characteristics of the projection optical system; a heat dissipation step of dissipating heat accumulated in the shield by the adjustment step; an exposure step of exposing the substrate via the projection optical system after the heat dissipation step; configured to: the control unit is further configured to determine the amount of heat dissipation from the shield in the heat dissipation step based on at least one of light irradiation conditions in the adjustment step and exposure conditions in the exposure step.

14. an exposure step of exposing a substrate according to the exposure method of any one of claims 1 to 12; a developing step of developing the exposed substrate; and manufacturing an article from the developed substrate.

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