Exposure method, exposure apparatus, and article manufacturing method

Abstract

To provide a technique advantageous to satisfying high-accuracy correction of focusing characteristics and high productivity.SOLUTION: An exposure method has: a step of performing a first exposure operation which is an exposure operation to a plurality of substrates of a first lot while correcting focusing characteristics of a projection optical system by predicting fluctuation in the focusing characteristics by using a prediction formula; and a step of performing a second exposure operation which is an exposure operation to a plurality of substrates of a second lot while correcting the focusing characteristics by a different correction method of the focusing characteristics corresponding to whether a parameter value for the first lot applied to the prediction formula has been updated.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] The required accuracy of overlay in semiconductor manufacturing processes is increasing year by year. For example, the tolerance of the variation in magnification due to exposure heat within one lot may be required to be 0.100 ppm or less. To achieve this level of accuracy, it is conceivable to implement closed correction, which involves calibration within the lot, but this would result in a decrease in productivity. From the viewpoint of productivity, a technology that predicts the dynamic variation in imaging characteristics due to exposure heat based on the exposure conditions and performs open correction is advantageous.

[0003] Patent Document 1 describes a technique for correcting imaging characteristics while maintaining accuracy even when the original or illumination conditions are changed by correcting errors in calculation parameters for predictive control of imaging characteristics after illumination conditions are changed. Patent Document 2 describes a technique for correcting imaging characteristics according to a combination of masks (product patterns) and illumination modes in addition to predicting fluctuations in imaging characteristics. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-29179 [Patent Document 2] JP 2006-24941 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, it was found that even if the prediction model is optimized to correctly predict the fluctuations in the imaging characteristics, the correction accuracy decreases depending on the state of the prediction model under the exposure conditions of the preceding lot.

[0006] The present invention provides a technique that is advantageous in achieving both highly accurate correction of imaging characteristics and high productivity. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided an exposure method comprising the steps of: performing a first exposure operation which is an exposure operation on a first lot of substrates while predicting fluctuations in imaging characteristics of a projection optical system using a prediction equation and correcting the imaging characteristics; and performing a second exposure operation which is an exposure operation on a second lot of substrates while correcting the imaging characteristics with a correction method for the imaging characteristics that differs depending on whether a parameter value for the first lot that is applied to the prediction equation has been updated. Effect of the Invention

[0008] According to the present invention, it is possible to provide a technique that is advantageous in achieving both highly accurate correction of imaging characteristics and high productivity. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an exposure apparatus. [Diagram 2] FIG. 13 is a diagram showing the relationship between shift and light amount during aerial image measurement. [Diagram 3] 11A and 11B are diagrams showing examples of magnification fluctuation and correction residuals according to a conventional method. [Figure 4] 11A and 11B are diagrams showing examples of magnification fluctuation and correction residuals according to a conventional method. [Diagram 5] 4 is a flowchart of a lot process according to the embodiment. [Figure 6] 4 is a flowchart of a lot process according to the embodiment. [Figure 7] 4 is a flowchart of a lot process according to the embodiment. [Figure 8] 6A to 6C are diagrams showing examples of magnification fluctuation and correction residuals according to the method of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] FIG. 1 is a diagram showing the configuration of an exposure apparatus 1 in an embodiment. In this specification and the drawings, directions are indicated in an XYZ coordinate system with a horizontal plane as the XY plane. In general, a substrate 110 is placed on a substrate stage 111 so that its surface is parallel to the horizontal plane (XY plane). Therefore, in the following, directions that are orthogonal to each other in a plane along the surface of the substrate 110 are referred to as the X-axis and Y-axis, and a direction perpendicular to the X-axis and Y-axis is referred to as the Z-axis. In the following, 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.

[0012] 1, light emitted from a light source 101 enters an illumination optical system 102. A desired effective light source distribution is formed by the light that enters the illumination optical system 102 at a diffractive optical element 103. The light having the desired effective light source distribution is irradiated onto an original 104 (reticle) surface. The light irradiated onto a pattern drawn on the original 104 reaches a substrate 110 via a projection optical system 107, whereby the pattern on the original 104 is projected (for example, reduced projection) and exposed.

[0013] The original stage 106 holds the original 104 and can be driven to scan in the Y direction. The substrate stage 111 holds and moves a substrate 110 (wafer). During exposure, the substrate stage 111 holds the substrate 110 and can be driven to scan in the opposite direction to the scan drive direction of the original stage 106. When exposure of one shot area is completed, the substrate stage 111 can be driven in steps to expose the next shot.

[0014] The control unit 100 comprehensively controls each unit of the exposure apparatus. The control unit 100 can be configured, for example, by a general-purpose or dedicated processor with a program embedded in memory. Alternatively, the control unit 100 may be configured by a PLD (abbreviation for Programmable Logic Device) such as an FPGA (abbreviation for Field Programmable Gate Array) or an ASIC (abbreviation for Application Specific Integrated Circuit). Alternatively, the control unit 100 may be configured by a combination of all or part of the processor, PLD, and ASIC.

[0015] The diffractive optical element 103 is disposed on a plane conjugate with the original 104, which is the illuminated surface (image surface), or on a plane that has a Fourier transform relationship with the pupil plane of the illumination optical system 102. The diffractive optical element 103 converts the light intensity distribution of the light beam from the light source 101 by diffraction to form a desired light intensity distribution on a predetermined surface, such as the pupil plane of the illumination optical system 102, which is a plane conjugate with the pupil plane of the projection optical system 107, or a plane conjugate thereto. The diffractive optical element 103 may use a computer generated hologram (CGH) designed by a computer so that a desired diffraction pattern is obtained on the diffraction pattern plane. The light source shape formed on the pupil plane of the projection optical system 107 is called the "effective light source shape." In this specification, the "effective light source" refers to the light intensity distribution or the angular distribution of light on the illuminated surface and its conjugate plane. In one example, the diffractive optical element 103 may be a diffractive optical element selected from a plurality of diffractive optical elements that convert the light beam from the light source 101 into different light intensity distributions. The multiple diffractive optical elements are mounted, for example, in multiple slots of a turret (not shown). The multiple diffractive optical elements can form different effective light source shapes. The multiple diffractive optical elements can include a diffractive optical element for modified illumination during exposure. Depending on the effective light source shape of the modified illumination, the illumination mode is named, for example, small σ illumination, large σ illumination, annular illumination, dipole illumination, quadrupole illumination, etc.

[0016] An original reference plate 105 separate from the original 104 is configured on the original stage 106, and original-side marks 113 for aerial image measurement are arranged on the original reference plate 105. The original-side marks 113 can be a periodically arranged line-and-space pattern. Furthermore, a substrate reference plate 112 is configured on the substrate stage 111, and a substrate-side mark 114 for aerial image measurement is arranged on the substrate reference plate 112. The substrate-side mark 114 can be a line-and-space pattern with the same pitch as the line-and-space pattern of the original-side mark 113. Furthermore, a photodetector 115 is configured below the substrate reference plate 112.

[0017] The lines of the line-and-space patterns in each of the original-side mark 113 and the substrate-side mark 114 may be made of chrome, and the spaces may be made of glass. The original stage 106 scans and drives in the Y direction so that the light emitted from the light source 101 is irradiated onto the original-side mark 113 on the original reference plate 105 via the illumination optical system 102, and then stops. The light that has passed through the original-side mark 113 on the original reference plate 105 reaches the substrate-side mark 114 on the substrate reference plate 112 via the projection optical system 107. The light that has reached the original-side mark 114 passes through the substrate-side mark 114 on the substrate reference plate 112, and reaches the photodetector 115.

[0018] Next, aerial image measurement, which is a measurement method for measuring image shift, will be described. Light emitted from the light source 101 is irradiated onto the original-side mark 113 via the illumination optical system 102, and the image of the original-side mark 113 is reduced and projected onto the substrate-side mark 114 by the projection optical system 107. When the substrate stage 111 is driven to scan in the X direction perpendicular to the optical axis direction in the reduced and projected state, the reduced and projected image of the original-side mark 113 overlaps with the substrate-side mark 114 at the imaging position of the projection optical system 107, so that the amount of light received by the photodetector 115 is maximized. Conversely, when the substrate-side mark 114 deviates from the imaging position of the projection optical system 107, the overlap between the reduced and projected image of the original-side mark 113 and the substrate-side mark 114 decreases, so that the amount of light received by the photodetector 115 gradually decreases.

[0019] 2 shows an example of the change in light amount when the substrate stage 111 is driven to scan in the X direction across the imaging position of the projection optical system 107, with the image of the original-side mark 113 reduced and projected onto the substrate-side mark 112. In FIG. 2, the horizontal axis indicates the position of the substrate stage 111 in the X direction, and the vertical axis indicates the amount of light received by the photodetector 115. The amount of light received by the photodetector 115 versus the position of the substrate stage 111 in the X direction forms an upwardly convex curve. The peak position of this curve is the imaging position of the projection optical system 107, and the difference from the reference position is the image shift (Δ). Note that the method for finding the image shift is not limited to this method. The image shift may be found by other methods.

[0020] A plurality of original-side marks 113 (for example, two marks) are arranged at different positions in the X direction, and the above-mentioned image shift measurement is performed for each original-side mark, and the magnification can be obtained from each image shift measurement result and multiple X-direction spans converted to the image side. In this specification, this is called "magnification measurement" as one of the measurements of imaging characteristics.

[0021] Next, prediction of the fluctuation in the imaging characteristics of the projection optical system 107 caused by exposure heat (hereinafter referred to as "exposure history") will be described.

[0022] Consider a case where exposure light is irradiated onto a mark on the original 104, and an image of the mark is formed on the substrate stage 111 via the projection optical system 107. When the exposure light is irradiated onto the projection optical system 107, the exposure energy is absorbed by the glass material of the lens constituting the projection optical system 107 itself or by an anti-reflection film on the lens surface, the temperature of the lens rises, and the refractive index of the lens changes. When the refractive index of the lens constituting the projection optical system 107 changes, the imaging characteristics change. Here, the imaging characteristics include wavefront aberration, focus, magnification, distortion, field curvature, astigmatism, etc., but in this specification, the prediction model of the exposure history is explained using magnification. The magnification of the projection optical system 107 caused by the exposure heat is called the "exposure magnification."

[0023] The exposure apparatus 1 includes a correction unit 120 that corrects (adjusts) the imaging characteristics. In one example, the correction unit 120 can adjust at least one of the position, posture, shape, and temperature of a part of the optical elements (e.g., lenses) that constitute the projection optical system 107. The correction unit 120 includes, for example, a mechanism for driving the lens in the optical axis direction (Z direction) and in a direction perpendicular to the optical axis direction, a mechanism for driving a support unit that supports the optical element, a mechanism for applying stress (a force that pushes or pulls the optical element) to the optical element, and a mechanism for heating or cooling the optical element. The driving of these components in the correction unit 120 is controlled by the control unit 100. However, the correction unit may adjust the imaging characteristics by performing at least one of driving the optical elements of the projection optical system 107, driving the original stage 106, and driving the substrate stage 111. The control unit 100 can correct the magnification by predicting a magnification change and controlling the correction unit 120 to cancel the predicted magnification change.

[0024] In mass production factories for semiconductor devices, a specific number of substrates (e.g., 25 substrates) are generally managed as one lot. Therefore, exposure processing jobs are also submitted on a lot-by-lot basis. When starting exposure processing for the first lot, the control unit 100 performs magnification measurement before exposure of the leading substrate begins to obtain the magnification before exposure. This is called the leading lot magnification. The leading lot magnification includes the static magnification of the projection optical system 107 and the positioning error of the original-side mark 113 of the original (hereinafter referred to as "original writing error").

[0025] After exposure is started, the control unit 100 performs magnification measurement before exposure of each substrate or a specified substrate to obtain the variation in exposure magnification within the lot. This is called the "intra-lot magnification." The intra-lot magnification includes the static magnification of the projection optical system 107, the original drawing error, and the exposure magnification that varies due to exposure.

[0026] Next, when a second lot using a master different from the one used in the first lot is started, the control unit 100 performs magnification measurement in the same manner as the first lot to obtain the leading lot magnification and the intra-lot magnification. The leading lot magnification at this time includes the effects of the static magnification of the projection optical system 107, the master drawing error different from that of the first lot, and the exposure magnification of the first lot. The intra-lot magnification includes the static magnification of the projection optical system 107, the master drawing error different from that of the first lot, and the exposure magnification of the second lot.

[0027] In this way, exposure processing of multiple lots is performed while magnification measurements are performed at the beginning of the lot and within the lot. The exposure processing repeated within one lot is performed according to an exposure recipe (hereinafter simply referred to as "recipe"). The recipe includes exposure conditions that can be specified by the user. The exposure conditions can include, for example, original identification information, illumination conditions, exposure dose, shot size, number of shots, resist reflectance, etc. The exposure conditions can differ between lots. For example, different originals and / or different illumination modes can be used between lots.

[0028] The control unit 100 uses the following model formulas or prediction formulas (1), (2), and (3) for the acquired magnification fluctuation to determine parameter values ​​to be applied to the prediction formulas for each exposure condition. The parameter values ​​are prediction coefficient values ​​that represent the saturation amount at the unit exposure load for each time constant of the exposure magnification. φ represents the predicted amount of the modeled exposure magnification, and the subscript N represents the measurement timing of the magnification. In this specification, a parameter P of a model with three time constants K is used. Therefore, the subscript m represents the model number. α represents the exposure load, and has a different value depending on the exposure condition. The exposure load α is represented by the original transmittance R, the exposure amount D, the shot size A, the number of shots Num between two magnification measurements, and the time T between the two magnification measurements. The subscript c means that the parameter changes for each exposure condition. Other parameters such as resist reflectance may be used in the calculation of the exposure load.

[0029] φ N =φ 1N +φ2N +φ 3N (1) φ mN =P cm *α cN -(P cm *α cN -φ mN-1 )*exp(-T N / K m ) ···(2) α cN =(R c *D c *A c *Num cN ) / T N (3) FIG. 3 shows the magnification fluctuation when the leading magnification and intra-lot magnification are measured by randomly flowing the lots under three exposure conditions, and the difference between the measured magnification fluctuation and the predicted value by the prediction model described above (correction residual). It is assumed that the parameter values ​​are determined (updated) under exposure condition 1 and exposure condition 2 so that the difference between the predicted value of the prediction model and the actual magnification fluctuation is small. The determination (updating) can be performed, for example, by fitting the model formula using the least squares method with the parameter P for each exposure condition as a variable. In this specification, this parameter determination process is called "optimization". On the other hand, it is assumed that no optimization is performed under exposure condition 3. Looking at FIG. 3, the correction residual is small during the period (0 to 3150 sec) when the lots under exposure condition 1 and exposure condition 2, which are optimized, flow alternately. However, during the period (3150 to 3500 seconds) when the recipe is loaded for the first time and a lot of non-optimized exposure condition 3 is being processed, the prediction model is unable to correctly predict the actual magnification fluctuation, and the maximum correction residual (absolute value) becomes large at 1.060 ppm.

[0030] In lots with exposure conditions that are not optimized, the correction residual becomes large, which affects the exposure results. To prevent this, it is necessary to measure the intra-lot magnification for lots with exposure conditions that are not optimized and correct the magnification based on the measurement value. Figure 4 shows the results of measuring the intra-lot magnification for a lot with exposure condition 3 and correcting the magnification based on the obtained measurement value. During the period when the lot with exposure condition 3 is in process (3150 to 3500 seconds), the magnification is corrected based on the measurement value of the intra-lot magnification, so the correction residual is smaller compared to the case in Figure 3.

[0031] However, in the lot of exposure condition 1 that was sent after exposure condition 3, the maximum correction residual remained large at 0.546 ppm (3500 to 3900 sec) despite the optimization. This is because, at the timing of switching from exposure condition 3 to exposure condition 1, the φ mN-1 This is because the actual magnification fluctuation is not correctly reflected in the exposure condition 1. Furthermore, in the next lot (3900 to 4200 sec) under exposure condition 1, the maximum correction residual error was large at 0.223 ppm due to the influence of exposure condition 3.

[0032] An exposure method including a magnification correction process in this embodiment will be described with reference to the flowchart in Fig. 5. The exposure method in this embodiment includes a step of performing a first exposure operation, which is an exposure operation for a first lot of substrates, while predicting a fluctuation in the imaging characteristics of the projection optical system 107 using a prediction formula and correcting the imaging characteristics. The exposure method further includes a step of performing a second exposure operation, which is an exposure operation for a second lot of substrates, while correcting the imaging characteristics with a correction method for the imaging characteristics that differs depending on whether the parameter values ​​for the first lot applied to the prediction formula have been updated. The flowchart in Fig. 5 shows the process in the second exposure operation (second lot processing) after the first exposure operation.

[0033] When the job for the second lot is started, in S2, the control unit 100 determines whether the parameter values ​​(coefficient values) for the first lot, which is the lot preceding the second lot, have been optimized (updated). This can be done, for example, by providing a flag in the recipe indicating whether the parameter P has been optimized or not, and making the determination based on the value of the flag. If it is determined that the parameter values ​​for the first lot have been optimized, the process proceeds to S4. If it is determined that the parameter values ​​for the first lot have not yet been optimized, the process proceeds to S5.

[0034] The processing proceeds to S4 when it is determined that the non-optimized recipe will not affect the processing of the subsequent lots after the second lot. Therefore, in S4, the control unit 100 applies the parameter values ​​for the second lot, which are determined in advance, to the prediction formula during the second exposure operation to calculate a predicted value of the imaging characteristics (here, the magnification fluctuation), and corrects the imaging characteristics based on the calculated predicted value. Specifically, the correction of the imaging characteristics is performed by controlling the correction unit 120 to cancel the predicted magnification fluctuation.

[0035] On the other hand, S5 is a process when the parameter values ​​for the first lot have not been updated. In S5, the control unit 100 measures the imaging characteristics (here, magnification fluctuation) during the second exposure operation, and corrects the imaging characteristics based on the measurement value obtained by the measurement. Specifically, the correction of the imaging characteristics is performed by controlling the correction unit 120 to cancel the predicted magnification fluctuation. Thereafter, in S6, the control unit 100 calculates and stores the maximum measurement value in the second lot. The maximum measurement value may be the maximum measurement value of the magnification within the lot, or may be the maximum difference between the magnification at the beginning of the lot and the magnification within the lot. In addition, the control unit 100 rewrites the value of a flag related to optimization of parameter values ​​in the recipe to a value indicating that optimization has been completed.

[0036] A further decision condition for branching to S4 or S5 may be added. Figures 6 and 7 show a flowchart in which a further decision condition for branching to S4 or S5 is added.

[0037] In FIG. 6, in S1, the control unit 100 determines whether the parameter values ​​(coefficient values) for the second lot have been optimized (updated). As described above, this can be done by, for example, providing a flag in the recipe indicating whether the parameter P has been optimized or not, and making the determination based on the value of the flag. If it is determined that the parameter values ​​for the second lot have been optimized, the process proceeds to S2. If it is determined that the parameter values ​​for the second lot have not been optimized, the process proceeds to S5. Thus, according to the example of FIG. 6, even if the parameter values ​​for the second lot have not been updated, the measurement of the imaging characteristics is performed, and the imaging characteristics are corrected based on the measurement values ​​obtained by the measurement (S5).

[0038] In FIG. 7, in S3, the control unit 100 judges whether the correction residual of the first lot (previous lot) is within the allowable range. Here, for example, the control unit 100 judges whether the measurement maximum value of the first lot is within the threshold value. The measurement maximum value may be the maximum measurement value of the intra-lot magnification in the first lot, or may be the maximum value of the difference between the leading magnification of the lot and the intra-lot magnification. If it is judged that the correction residual of the first lot is within the allowable range in S3, the process proceeds to S4. Thus, according to the example of FIG. 7, although it is judged that the parameter value for the first lot is optimized (updated) in S2, if it is judged that the correction residual of the first lot is not within the allowable range in S3, the process proceeds to S5. This is because it is judged that the influence of the recipe that is not optimized still exists in this case. In S5, as described above, the measurement of the imaging characteristics is performed, and the imaging characteristics are corrected based on the measurement value obtained by the measurement.

[0039] FIG. 8 shows the result of magnification correction according to the process flow shown in FIG. 5, FIG. 6, or FIG. 7. According to the conventional example in FIG. 4, in the lot (3500-3900 sec) of exposure condition 1 that flowed after exposure condition 3, the maximum correction residual within the lot was 0.546 ppm as described above. However, since the immediately preceding exposure condition 3 was not optimized, in this embodiment, the magnification is corrected based on the measurement value of the magnification within the lot for exposure condition 1, which corresponds to the above-mentioned second lot. This results in a small final correction residual, as shown in FIG. 8.

[0040] Furthermore, according to the conventional example of FIG. 4, in the next lot (3900-4200 sec) of exposure condition 1, the maximum correction residual within the lot was 0.223 ppm as described above. However, if the maximum measured value within the previous lot is 0.546 ppm, which is equivalent to the correction residual, and the threshold value is 0.100 ppm, the maximum measured value within the previous lot exceeds the threshold value. Therefore, in this embodiment, the magnification is corrected based on the measured value of the magnification within the lot. As a result, the final correction residual becomes smaller, as shown in FIG. 8.

[0041] Furthermore, in the next lot (4200-4600 sec) under exposure condition 2, the maximum measurement value of the previous lot is 0.223 ppm, which is equivalent to the correction residual, and the maximum measurement value in the previous lot exceeds the threshold value. Therefore, in this embodiment, the magnification is corrected based on the measurement value of the magnification within the lot. This reduces the final correction residual, as shown in FIG. 8. Since the maximum correction residual of the lot at this point is 0.098 ppm, there is no need to measure the magnification within the lot for the next lot (4600-4900 sec) under exposure condition 1, and only magnification correction using the prediction model is performed.

[0042] In this way, according to this embodiment, the correction method is determined according to the optimization state of the immediately preceding lot, which makes it possible to improve the accuracy of magnification correction while suppressing the decrease in productivity due to magnification measurement within the lot.

[0043] The above-mentioned example of the correction process changes the correction method depending on whether the previous lot has been optimized or not. However, even if the previous lot has been optimized, depending on the conditions at the time of optimization and the time elapsed since the optimization, it is possible that prediction model parameters that cannot accurately predict the actual magnification fluctuation may have been determined. Therefore, in the following cases, even if the previous lot has been optimized, the magnification of the current lot may be corrected based on the measured value of the magnification within the lot. (a) When the temperature of an optical element (e.g., a lens) constituting the projection optical system 107 during optimization (update) is higher than a predetermined temperature, or (b) If the time elapsed since the optimization (update) time exceeds a specified time.

[0044] In the above embodiment, the magnification caused by exposure heat has been described, but the present invention may be applied to other aberrations such as focus, distortion, curvature of field, astigmatism, and the like.

[0045] <Embodiment of the article manufacturing method> The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as microdevices such as semiconductor devices and elements having a fine structure. The article manufacturing method of the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the above-mentioned exposure apparatus (a step of exposing the substrate), and a step of developing the substrate on which the latent image pattern has been formed in the step. Furthermore, the manufacturing method includes other well-known steps (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to conventional methods.

[0046] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for implementing one or more of the functions.

[0047] The disclosure of the present specification includes at least the following exposure method, exposure apparatus, and article manufacturing method. (Item 1) performing a first exposure operation, which is an exposure operation for a first lot of substrates, while predicting a fluctuation in an imaging characteristic of a projection optical system using a prediction formula and correcting the imaging characteristic; performing a second exposure operation, which is an exposure operation for a plurality of substrates of a second lot, while correcting the imaging characteristics using a correction method for the imaging characteristics that differs depending on whether the parameter values ​​for the first lot that are applied to the prediction formula have been updated; An exposure method comprising the steps of: (Item 2) when the parameter values ​​for the first lot have been updated, during the second exposure operation, a parameter value for the second lot that has been determined in advance is applied to the prediction formula to correct the imaging characteristics; if the parameter values ​​for the first lot have not been updated, measuring the imaging characteristics during the second exposure operation, and correcting the imaging characteristics based on the measurement values ​​obtained by the measurement. 2. The exposure method according to item 1, (Item 3) even if the parameter values ​​for the second lot have not been updated, the imaging characteristics are measured, and the imaging characteristics are corrected based on the measurement values ​​obtained by the measurement. 3. The exposure method according to item 2, (Item 4) the parameter values ​​for the first lot have been updated, but if a correction residual when the updated parameter values ​​are applied to the prediction formula to correct the imaging characteristics is not within an allowable range, measuring the imaging characteristics and correcting the imaging characteristics based on a measurement value obtained by the measurement. 4. The exposure method according to item 2 or 3. (Item 5) the parameter values ​​for the first lot have been updated, but if the temperature of an optical element constituting the projection optical system at the time of the update is higher than a predetermined temperature, the imaging characteristics are measured, and the imaging characteristics are corrected based on the measurement value obtained by the measurement. 5. The exposure method according to any one of items 2 to 4, (Item 6) when the parameter values ​​for the first lot have been updated but the time elapsed since the update exceeds a predetermined time, the imaging characteristics are measured, and the imaging characteristics are corrected based on the measurement values ​​obtained by the measurement. 5. The exposure method according to any one of items 2 to 4, (Item 7) 7. The exposure method according to any one of items 1 to 6, wherein the imaging characteristics include at least one of magnification, focus, distortion, field curvature, and astigmatism. (Item 8) a projection optical system that projects a pattern of the original onto a substrate; a correction unit that corrects the imaging characteristics of the projection optical system; A control unit; having The control unit is during a first exposure operation which is an exposure operation for a plurality of substrates in a first lot, predicting a fluctuation in an imaging characteristic of the projection optical system using a prediction formula, and controlling the correction unit so as to correct the imaging characteristic based on a result of the prediction; controlling the correction unit to correct the imaging characteristics by a different correction method for the imaging characteristics depending on whether a parameter value for the first lot to be applied to the prediction formula has been updated during a second exposure operation which is an exposure operation for a plurality of substrates of a second lot; An exposure apparatus comprising: (Item 9) exposing a substrate according to the exposure method according to any one of items 1 to 7; developing the exposed substrate; and producing an article from the developed substrate.

[0048] The invention is not limited to the above-described embodiments, and various modifications and variations are possible 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]

[0049] 1: exposure apparatus, 101: light source, 102: illumination optical system, 103: diffractive optical element, 104: original, 106: original stage, 107: projection optical system, 110: substrate, 111: substrate stage

Claims

1. performing a first exposure operation, which is an exposure operation for a first lot of substrates, while predicting a fluctuation in an imaging characteristic of a projection optical system using a prediction formula and correcting the imaging characteristic; performing a second exposure operation which is an exposure operation for a plurality of substrates of a second lot while correcting the imaging characteristics by a correction method for the imaging characteristics which differs depending on whether the parameter values ​​for the first lot applied to the prediction formula have been updated; An exposure method comprising the steps of:

2. when the parameter values ​​for the first lot have been updated, during the second exposure operation, a parameter value for the second lot that has been determined in advance is applied to the prediction formula to correct the imaging characteristics; if the parameter values ​​for the first lot have not been updated, measuring the imaging characteristics during the second exposure operation, and correcting the imaging characteristics based on the measurement values ​​obtained by the measurement.

2. The exposure method according to claim 1.

3. even if the parameter values ​​for the second lot have not been updated, the imaging characteristics are measured, and the imaging characteristics are corrected based on the measurement values ​​obtained by the measurement.

3. The exposure method according to claim 2.

4. the parameter values ​​for the first lot have been updated, but if a correction residual when the updated parameter values ​​are applied to the prediction formula to correct the imaging characteristics is not within an allowable range, measuring the imaging characteristics and correcting the imaging characteristics based on a measurement value obtained by the measurement.

3. The exposure method according to claim 2.

5. the parameter values ​​for the first lot have been updated, but if the temperature of an optical element constituting the projection optical system at the time of the update is higher than a predetermined temperature, the imaging characteristics are measured, and the imaging characteristics are corrected based on the measurement value obtained by the measurement.

3. The exposure method according to claim 2.

6. when the parameter values ​​for the first lot have been updated but the time that has elapsed since the update exceeds a predetermined time, measuring the imaging characteristics and correcting the imaging characteristics based on the measurement values ​​obtained by the measurement.

3. The exposure method according to claim 2.

7. 2. The exposure method according to claim 1, wherein the imaging characteristics include at least one of magnification, focus, distortion, field curvature, and astigmatism.

8. a projection optical system that projects the pattern of the original onto the substrate; a correction unit that corrects the imaging characteristics of the projection optical system; A control unit; having The control unit is during a first exposure operation which is an exposure operation for a plurality of substrates in a first lot, predicting a fluctuation in an imaging characteristic of the projection optical system using a prediction formula, and controlling the correction unit so as to correct the imaging characteristic based on a result of the prediction; controlling the correction unit to correct the imaging characteristics by a correction method for the imaging characteristics that differs depending on whether a parameter value for the first lot that is applied to the prediction formula has been updated during a second exposure operation that is an exposure operation for a plurality of substrates of a second lot; An exposure apparatus comprising:

9. exposing a substrate according to the exposure method of any one of claims 1 to 7; developing the exposed substrate; and producing an article from the developed substrate.

Images