JP6298345B2 - Measuring method, exposure apparatus, and article manufacturing method - Google Patents

Description

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

  2. Description of the Related Art When manufacturing devices (semiconductor devices, magnetic storage media, liquid crystal display elements, etc.) by a photolithography process, an exposure apparatus that transfers a mask pattern onto a substrate is used. In order to accurately transfer the mask pattern to the substrate and improve productivity (throughput), high-speed and high-precision focusing (focus calibration) and alignment between the mask and the substrate (alignment) Is required to do.

  Patent Document 1 discloses a technique for performing high-speed and high-precision alignment between a mask and a substrate. In Patent Document 1, target accuracy of alignment is set, and the number of times (measurement number) of measuring the positional deviation between the mask and the substrate is determined according to the target accuracy. As a result, when the target accuracy is low, the number of measurements can be reduced and the measurement can be performed in a short time, and when the target accuracy is high, the number of measurements can be increased and highly accurate measurement can be performed.

  Also, as one of the focus calibration and alignment methods, measurement of the relative position of the mask and the substrate (substrate displacement) and measurement of the focus state of light from the projection optical system are performed via the projection optical system. There is a TTL (Through The Lens) method.

JP 59-99206 A

  However, in the focus calibration and alignment by the TTL method, since measurement is performed via the projection optical system, the measurement accuracy changes in accordance with fluctuations in the temperature in the projection optical system due to the heat of the exposure light. In the technique disclosed in Patent Document 1, since the target accuracy and the number of measurements are uniquely set, it is not possible to cope with a change in measurement accuracy. For example, when the actual measurement accuracy is lower than the assumed measurement accuracy, the target accuracy cannot be achieved even if the measurement is performed the determined number of times. On the other hand, when the actual measurement accuracy is higher than the assumed measurement accuracy, the measurement is performed more times than necessary, and the productivity is lowered.

  The present invention has been made in view of such a problem of the prior art, and provides an advantageous technique for measuring the focus state of light from the projection optical system and the positional deviation of the substrate via the projection optical system. For illustrative purposes.

  In order to achieve the above object, a measurement method according to an aspect of the present invention includes a focus state of light from the projection optical system or an exposure apparatus that transfers a mask pattern to a substrate via the projection optical system. A measurement method for measuring a positional deviation of the substrate via a projection optical system, wherein the measurement is performed once based on a first step of setting a target accuracy of the measurement and a state of the projection optical system. Determining the number of times of measurement necessary to satisfy the target accuracy, based on the second step of determining the accuracy of the measurement at the time and the accuracy of the measurement obtained in the second step. And a third step of measuring the number of times.

  Further objects and other aspects of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, for example, it is possible to provide a technique advantageous for measuring the focus state of light from the projection optical system and the positional deviation of the substrate via the projection optical system.

It is the schematic which shows the structure of the exposure apparatus as 1 side surface of this invention. It is a figure which shows an example of a structure of the pattern for a measurement. It is a figure which shows an example of the relationship between the light quantity detected with a sensor, and the position of the Z-axis direction of a substrate stage. 2 is a flowchart for explaining the operation of the exposure apparatus shown in FIG. It is a figure which shows an example of the temperature change in each position in the projection optical system of the exposure apparatus shown in FIG. It is the schematic which shows the structure of the exposure apparatus as 1 side surface of this invention. It is a flowchart for demonstrating operation | movement in the exposure apparatus shown in FIG. It is a figure which shows an example of the relationship between time and the measurement precision of the position shift of a mask and a board | substrate. It is a figure which shows an example of a structure of the alignment mark provided in the mask. It is a figure which shows an example of a structure of the alignment mark provided in the board | substrate.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is a schematic diagram showing a configuration of an exposure apparatus 100 in the first embodiment of the present invention. The exposure apparatus 100 is a lithography apparatus that transfers a mask pattern onto a substrate by a step-and-scan method. However, the exposure apparatus 100 can also apply a step-and-repeat method and other exposure methods. As shown in FIG. 1, the exposure apparatus 100 includes an illumination optical system 1, a mask stage 3, a projection optical system 4, a substrate stage 6, a control unit 7, a laser interferometer 8, a reference mark 9, The sensor 10, the laser interferometer 11, the acquisition unit 12, and the setting unit 14 are included.

  The illumination optical system 1 illuminates the mask 2 with light from a light source (not shown). The illumination optical system 1 includes, for example, a lens, a mirror, an optical integrator, a diaphragm, and the like, and illuminates an illumination area on the mask 2 with light having a uniform illuminance distribution.

  The mask stage 3 moves while holding the mask 2 on which an actual device pattern (circuit pattern) is drawn. The mask stage 3 is configured to be capable of two-dimensional movement in a plane perpendicular to the optical axis of the projection optical system 4, that is, in the XY plane, and to be rotatable in the θZ direction. The mask stage 3 is uniaxially driven or uniaxially driven by a driving device (not shown) such as a linear motor.

  A mirror is disposed on the mask stage 3, and a laser interferometer 8 is disposed at a position facing the mirror. The position and rotation angle of the mask stage 3 in the two-dimensional direction are measured in real time by the laser interferometer 8, and the measurement result is output to the control unit 7. The controller 7 controls the driving device based on the measurement result of the laser interferometer 8 to position the mask 2 held on the mask stage 3.

  The projection optical system 4 includes a plurality of optical elements (such as lenses and mirrors), and projects the pattern image of the mask 2 onto the substrate 5 at a predetermined projection magnification. The mask 2 (the pattern thereof) and the substrate 5 have a conjugate positional relationship via the projection optical system 4.

  The substrate stage 6 moves while holding the substrate 5. The substrate stage 6 includes, for example, a Z stage that holds the substrate 5 via a chuck, an XY stage that supports the Z stage, and a base that supports the XY stage. The substrate stage 6 is driven by a driving device such as a linear motor. Further, the substrate stage 6 is provided with a reference mark 9 (a reference plate on which the reference mark 9 is provided) and a sensor 10 that detects the amount of light that has passed (transmitted) through the reference mark 9.

  A mirror is disposed on the substrate stage 6, and a laser interferometer 11 is disposed at a position facing the mirror. The positions of the substrate stage 6 in the X-axis direction, Y-axis direction, and θZ direction are measured in real time by the laser interferometer 11, and the measurement results are output to the control unit 7. Further, the position of the substrate stage 6 in the Z-axis direction, the position in the θX direction and the θY direction are also measured in real time by a laser interferometer (not shown), and the measurement result is output to the control unit 7. The controller 7 controls the drive device based on the measurement result of the laser interferometer, and positions the substrate 5 held on the substrate stage 6.

  The acquisition unit 12 includes at least one of the state of the projection optical system 4, specifically, the temperature, humidity, and pressure in the projection optical system. In the present embodiment, the acquisition unit 12 is arranged at a predetermined position of the projection optical system 4 and includes four temperature sensors 12A, 12B, 12C, and 12D that measure the temperature in the projection optical system. The temperature (temperature information) at each position in the projection optical system measured by each of the temperature sensors 12A to 12D is output to the control unit 7. In the present embodiment, the four temperature sensors 12A to 12D are arranged in the projection optical system, but the number of arrangement of the temperature sensors 12A to 12s is not limited to four.

  The setting unit 14 includes an input device for inputting instructions and information from the user, and sets various information necessary for the operation of the exposure apparatus 100 according to the user input. In this embodiment, the setting unit 14 measures the focus state of light from the projection optical system 4 necessary for focus calibration, and measures the positional deviation of the substrate 5 necessary for alignment between the mask 2 and the substrate 5. Set the target accuracy. The positional deviation of the substrate 5 includes a positional deviation between the mask 2 and the substrate 5 and a positional deviation of the substrate 5 from the reference position.

  The control unit 7 includes a CPU, a memory, and the like, and controls the entire exposure apparatus 100 (operation). In the present embodiment, the control unit 7 not only controls processing related to exposure in the exposure apparatus 100 but also controls processing related to focus calibration and alignment. For example, based on the state of the projection optical system 4 acquired by the acquisition unit 12, the control unit 7 focuses the light from the projection optical system 4 necessary for focus calibration and the position of the substrate 5 necessary for alignment. The accuracy of one measurement of deviation is obtained. Then, the control unit 7 determines the number of times of measurement necessary for the measurement accuracy of the focus state of the light from the projection optical system 4 and the positional deviation of the substrate 5 to satisfy the target accuracy set by the setting unit 14. .

  In exposure, light (exposure light) emitted from the illumination optical system 1 passes through the mask 2 held by the mask stage 3 and enters the projection optical system 4. The light incident on the projection optical system 4 reaches the substrate 5. Thereby, the pattern of the mask 2 is transferred to the substrate 5 through the projection optical system 4.

  Here, an example of focus calibration in the exposure apparatus 100 will be described. First, the mask stage 3 is moved so that the measurement pattern provided on the mask 2 (or mask stage 3) is illuminated by the illumination optical system 1. FIG. 2 is a diagram illustrating an example of the configuration of the measurement pattern MP provided on the mask 2. The measurement pattern MP includes a pattern part MPa and a peripheral part MPb. The pattern part MPa is formed with a predetermined line width and pitch, and transmits light from the illumination optical system 1. The peripheral part MPb is formed around the pattern part MPa, and shields light from the illumination optical system 1.

  Next, the substrate stage 6 is moved so that the reference mark 9 provided on the substrate stage 6 is positioned at the exposure position. The reference mark 9 is a mark including a transmission pattern corresponding to the measurement pattern MP provided on the mask 2. A sensor 10 that detects the amount of light that has passed through the reference mark 9 is disposed under the reference mark 9.

Next, the substrate stage 6 is slightly moved in the Z-axis direction to obtain a position (coordinate position) Z ₀ at which the amount of light detected by the sensor 10 is maximized. FIG. 3 is a diagram illustrating an example of the relationship between the amount of light detected by the sensor 10 and the position of the substrate stage 6 in the Z-axis direction. The position Z ₀ where the amount of light detected by the sensor 10 is maximum is a position where the measurement pattern MP provided on the mask 2 and the reference mark 9 are optically conjugate. Therefore, by determining the position Z ₀ to the amount of light detected by the sensor 10 becomes maximum, it is possible to determine the focus position of the light from the projection optical system 4. As described above, the measurement pattern MP, the reference mark 9 and the sensor 10 function as a measurement unit that measures the focus position of the light from the projection optical system 4, that is, the focus state.

  Next, the substrate 5 is positioned at the focus position of the light from the projection optical system 4 by moving the substrate stage 6 in the Z-axis direction by the shift amount of the focus position based on the focus position thus obtained. Can do.

  With reference to FIG. 4, the operation including focus calibration (correction of focus position deviation) in the exposure apparatus 100 will be described. As described above, this operation is performed by the control unit 7 comprehensively controlling each unit of the exposure apparatus 100.

  In S402, the setting unit 14 sets the focus position of the light from the projection optical system 4 necessary for the focus calibration, that is, the target accuracy of measurement of the focus state, according to the user input.

  In S <b> 404, the mask 2 is carried into the exposure apparatus 100 from the outside of the exposure apparatus 100, and the mask 2 is held on the mask stage 3. In step S <b> 406, the substrate 5 is carried into the exposure apparatus 100 from the outside of the exposure apparatus 100, and the substrate 5 is held on the substrate stage 6.

  In step S408, the control unit 7 determines whether to perform focus calibration. The determination criterion here may be, for example, a fixed time interval, may be for each substrate, or may be an exposure time (integrated exposure amount). Such a determination criterion is determined in advance and is set in the exposure apparatus 100 via the setting unit 14 or the like. When focus calibration is not performed, the process proceeds to S422, and when focus calibration is performed, the process proceeds to S410.

In S410, the control unit 7 obtains the accuracy of one measurement of the focus state of the light from the projection optical system 4 (that is, the measurement accuracy per one time). Specifically, the control unit 7 acquires temperature information measured by each of the temperature sensors 12A to 12D. FIG. 5 is a view showing an example of a temperature change at each position of the projection optical system 4 of the exposure apparatus 100. In FIG. 5, time is adopted on the horizontal axis, temperatures measured by the temperature sensors 12A to 12D arranged in the projection optical system are adopted on the vertical axis, and the start point of time is the exposure start time. And the control part 7 calculates | requires the measurement precision per time of the focus state of the light from the projection optical system 4 based on the temperature information acquired from temperature sensor 12A thru | or 12D. For example, if the temperatures measured by the temperature sensors 12A to 12D are T _A , T _B , T _C , and T _D , the measurement accuracy A ₁ per time of the focus state of the light from the projection optical system 4 is It calculates | requires by the following formula | equation (1).

_{A 1 = K 1 × R (} T A, T B, T C, T D) ··· (1)
In the formula _{(1), R (T A} , T B, T C, T D) , the temperature _{T A,} T B, the difference between the maximum temperature and minimum temperature of from _{T C} and _{T D} (temperature difference) It is. K ₁ is a proportionality constant, is obtained in advance from the simulation and actual experimental data, is set in the exposure apparatus 100 via a setting unit 14.

However, the formula (1) for obtaining the measurement accuracy A ₁ is an example, and the measurement accuracy A ₁ is obtained from other functions expressed by functions of the temperatures T _A , T _B , T _C, and T _D. May be. Thus, measurement accuracy A ₁ is (in this embodiment, the temperature within the projection optical system) of the state projection optical system 4 is determined using information indicative of a relation between the measurement accuracy.

In S412, the number of measurements necessary for the control unit 7 to satisfy the target accuracy set in S402 so that the measurement accuracy of the focus state of the light from the projection optical system 4 satisfies the measurement accuracy obtained in S410. Determine (number of measurements). For example, the target precision set in S402 and AT _1, when the measurement accuracy obtained in S410 and _{A 1,} measuring the number _{N 1} of the focus state of the light from the projection optical system 4 is determined by the following equation (2) Is done. However, since the measurement number N ₁ needs to be an integer, when the measurement number N ₁ does not become an integer, it is rounded up to an integer.

N ₁ = (A ₁ / AT ₁ ) ² (2)
In S414, the mask stage 3 and the substrate stage 6 are moved to a position where focus calibration is possible, that is, a position where the focus state of light from the projection optical system 4 can be measured. Specifically, as described above, the mask stage 3 is moved so that the measurement pattern MP provided on the mask 2 is illuminated by the illumination optical system 1, and the reference mark 9 provided on the substrate stage 6. The substrate stage 6 is moved so that is positioned at the exposure position.

In S416, the focus state of the light from the projection optical system 4 is measured using the measurement pattern MP, the reference mark 9, and the sensor 10. Specifically, as described above, the substrate stage 6 obtains a position Z ₀ of the light amount becomes maximum is detected by the sensor 10 while infinitesimal traveling in the Z-axis direction, of such position Z ₀ from the projection optical system 4 The light focus position.

  In S418, it is determined whether or not the measurement of the focus state of the light from the projection optical system 4 in S416 has reached the number of measurements determined in S412. If the measurement of the focus state of the light from the projection optical system 4 has not reached the number of measurements determined in S412, the process proceeds to S416, and the measurement of the focus state of the light from the projection optical system 4 is continued. If the measurement of the focus state of the light from the projection optical system 4 has reached the number of measurements determined in S412, the process proceeds to S420.

  In S420, the focus calibration, that is, the shift of the focus position is corrected. Specifically, the control unit 7 obtains the average focus position by averaging the focus positions obtained in S416 for the number of measurement times determined in S412. The average focus position thus obtained satisfies the target accuracy set in S402 due to the averaging effect. Then, based on the average focus position, the substrate stage 6 is moved in the Z-axis direction by the shift amount of the focus position.

  In S422, the substrate 5 is exposed. As described above, the mask 2 is illuminated by the light from the illumination optical system 1, and the pattern of the mask 2 is transferred to the substrate 5 via the projection optical system 4. In S424, the exposed substrate 5 is carried out of the exposure apparatus 100.

  In step S426, the control unit 7 determines whether all the substrates 5 have been exposed. When all the substrates 5 are exposed, the operation is terminated. On the other hand, when all the substrates 5 are not exposed (that is, there are unexposed substrates 5), the process proceeds to S406, and the next substrate 5 is carried into the exposure apparatus 100 from the outside of the exposure apparatus 100, The substrate 5 is held on the substrate stage 6.

  As described above, in this embodiment, the accuracy when the focus state of the light from the projection optical system 4 is measured once is obtained based on the state of the projection optical system 4, and the projection optical system 4 determines the accuracy based on the accuracy. The number of times of measurement of the light focus state is determined. Therefore, the exposure apparatus 100 can perform the set target accuracy (that is, high speed) without performing the measurement more than necessary even when the measurement accuracy of the focus state changes due to the change in the state of the projection optical system 4. In addition, highly accurate focus calibration) can be achieved. Thereby, the exposure apparatus 100 can expose the substrate 5 with high accuracy without reducing the productivity.

<Second Embodiment>
FIG. 6 is a schematic view showing the arrangement of an exposure apparatus 100A in the second embodiment of the present invention. The exposure apparatus 100A has the same configuration as the exposure apparatus 100 in the first embodiment, but a measurement unit (measurement pattern MP, reference mark 9 and sensor 10) that measures the focus state of light from the projection optical system 4. Instead, it has alignment measurement systems 15A and 15B. The alignment measurement systems 15A and 15B measure the positional deviation of the substrate 5 via the projection optical system 4 (that is, by the TTL method), as will be described later. The illumination optical system 1 is provided with an illuminance sensor 1A.

  With reference to FIG. 7, an operation including alignment between the mask 2 and the substrate 5 (correction of misalignment between the mask 2 and the substrate 5) in the exposure apparatus 100A will be described. Such an operation is performed by the control unit 7 controlling the respective units of the exposure apparatus 100A in an integrated manner.

  In step S <b> 702, the setting unit 14 sets a target accuracy for measuring the positional deviation of the substrate 5 necessary for alignment, that is, the positional deviation between the mask 2 and the substrate 5, in accordance with a user input.

  In S704, the mask 2 is carried into the exposure apparatus 100A from the outside of the exposure apparatus 100A, and the mask 2 is held on the mask stage 3. In S706, the substrate 5 is carried into the exposure apparatus 100A from the outside of the exposure apparatus 100A, and the substrate 5 is held on the substrate stage 6.

  In S708, the control unit 7 determines whether to perform alignment. The determination criterion here is determined in advance and is set in the exposure apparatus 100A via the setting unit 14 or the like. If the alignment is not performed, the process proceeds to S724. If the alignment is performed, the process proceeds to S710.

In S <b> 710, the control unit 7 calculates the accuracy of one measurement of the positional deviation between the mask 2 and the substrate 5. For example, the control unit 7 obtains the measurement accuracy A ₂ (t) of the positional deviation between the mask 2 and the substrate 5 at a certain time t according to the following equation (3).

A ₂ (t) = A ₂ (t−Δt) × exp (−Δt / K ₂ ) + IC × exp (1−Δt / K ₂ ) × D (3)
In Expression (3), Δt is a period for obtaining measurement accuracy, K ₂ is a time constant of change in measurement accuracy, and IC is a saturation value of change in measurement accuracy. Time constant K ₂ and the saturation value IC is obtained in advance from the simulation and actual experimental data, is set in the exposure apparatus 100A via a setting unit 14. In Equation (3), D is a parameter indicating the state of the projection optical system 4 at time t, specifically, whether or not the light from the illumination optical system 1 is incident on the projection optical system 4. The value is “0” or “1”. Regarding parameter D, when the illuminance sensor 1A disposed in the illumination optical system 1 detects light (exposure light), it is determined that the light from the illumination optical system 1 is incident on the projection optical system 4. To do. When the illuminance sensor 1A does not detect light, it is determined that the light from the illumination optical system 1 is not incident on the projection optical system 4. FIG. 8 is a diagram illustrating an example of the measurement accuracy A ₂ (t) of the positional deviation between the mask 2 and the substrate 5 obtained using the equation (3). In FIG. 8, the measurement accuracy A ₂ (t) is adopted on the vertical axis, and the time is adopted on the horizontal axis. However, the equation (3) for obtaining the measurement accuracy A ₂ (t) is an example, and the measurement accuracy A ₂ (t) may be obtained from another function expressed as a function of the time t.

In S712, based on the measurement accuracy obtained in S710 in the control unit 7, the number of measurements required for the measurement accuracy of the positional deviation between the mask 2 and the substrate 5 to satisfy the target accuracy set in S702 ( Determine the number of measurements). For example, the target precision set in S702 and AT _2, when the measurement accuracy obtained in S710 and _{A 2,} measuring the number _{N 2} of position deviation between the mask 2 and the substrate 5 is determined by the following equation (4) The However, since the measurement count N ₂ needs to be an integer, if the measurement count N ₂ does not become an integer, it is rounded up to an integer.

N ₂ = (A ₂ / AT ₂ ) ² (4)
In S714, the mask stage 3 and the substrate stage 6 are moved to positions where the alignment measurement systems 15A and 15B can measure the positional deviation between the mask 2 and the substrate 5. Specifically, the mask stage 3 is moved so that the alignment marks provided on the mask 2 can be measured by the alignment measurement systems 15A and 15B. FIG. 9 is a diagram illustrating an example of the configuration of the alignment mark AMM provided on the mask 2. The alignment mark AMM includes a pattern portion AMMa and a peripheral portion AMMb. The pattern part AMMa is formed with a predetermined line width and blocks light from the illumination optical system 1. The peripheral portion AMMb is formed around the pattern portion AMMa and transmits light from the illumination optical system 1. Further, the substrate stage 6 is moved so that the alignment marks provided on the substrate 5 can be measured by the alignment measurement systems 15A and 15B. FIG. 10 is a diagram illustrating an example of the configuration of the alignment mark AMS provided on the substrate 5. The alignment mark AMS includes a pattern portion AMSa and a peripheral portion AMSb. The pattern part AMSa has a predetermined line width and is formed so as not to reflect light from the illumination optical system 1. The peripheral portion AMSb is formed around the pattern portion AMSa so as to reflect the light from the illumination optical system 1.

  In S716, the alignment measurement systems 15A and 15B detect the relative positions (X, Y) between the alignment mark AMM and the alignment mark AMS, and measure the positional deviation between the mask 2 and the substrate 5.

  In S718, it is determined whether or not the measurement of the positional deviation between the mask 2 and the substrate 5 in S716 has reached the number of measurements determined in S712. If the measurement of the positional deviation between the mask 2 and the substrate 5 has not reached the number of measurements determined in S712, the process proceeds to S716 and the measurement of the positional deviation between the mask 2 and the substrate 5 is continued. If the measurement of the positional deviation between the mask 2 and the substrate 5 has reached the number of measurements determined in S712, the process proceeds to S720.

  In S720, the control unit 7 determines whether or not all alignment marks AMM and AMS have been detected by the alignment measurement systems 15A and 15B. If all the alignment marks AMM and AMS are not detected (there are undetected alignment marks AMM and AMS), the process proceeds to S714 to detect the next alignment marks AMM and AMS. On the other hand, if all the alignment marks AMM and AMS have been detected, the process proceeds to S722.

  In step S722, the alignment between the mask 2 and the substrate 5, that is, the positional deviation between the mask 2 and the substrate 5 is corrected. Specifically, the controller 7 averages the positional deviation between the mask 2 and the substrate 5 obtained in S716 for the number of times determined in S712, and obtains the average positional deviation. The average positional deviation thus determined satisfies the target accuracy set in S702 due to the averaging effect. Then, based on the average positional deviation, the mask stage 3 and the substrate stage 6 are moved to perform alignment (position alignment) between the mask 2 and the substrate 5.

  In S724, the substrate 5 is exposed. In the present embodiment, exposure is performed for each shot region of the substrate 5. Therefore, the mask 2 is illuminated by the light from the illumination optical system 1, and the pattern of the mask 2 is transferred to one shot area of the substrate 5 through the projection optical system 4.

  In step S <b> 726, the control unit 7 determines whether all shot areas of the substrate 5 have been exposed. If all the shot areas are not exposed (that is, there is an unexposed shot area), the process proceeds to S724 to expose the next shot area. On the other hand, if all the shot areas are exposed, the process proceeds to S728, and the substrate 5 that has exposed all the shot areas is carried out of the exposure apparatus 100A.

  In S730, the control unit 7 determines whether all the substrates 5 have been exposed. When all the substrates 5 are exposed, the operation is terminated. On the other hand, when all the substrates 5 are not exposed (that is, there are unexposed substrates 5), the process proceeds to S706, and the next substrate 5 is carried from the outside of the exposure apparatus 100A to the exposure apparatus 100A. The substrate 5 is held on the substrate stage 6.

As described above, in this embodiment, the accuracy when the measurement of the positional deviation between the mask 2 and the substrate 5 is performed once is obtained based on the state of the projection optical system 4, and the mask 2 and the substrate 5 are determined based on the accuracy. The number of times of measurement of misalignment is determined.
Therefore, the exposure apparatus 100A is set without performing the measurement more than necessary even when the state of the projection optical system 4 fluctuates and the measurement accuracy of the positional deviation between the mask 2 and the substrate 5 changes. Target accuracy (that is, high-speed and high-precision alignment) can be achieved. Thereby, the exposure apparatus 100A can expose the substrate 5 with high accuracy without reducing the productivity.

<Third Embodiment>
The article manufacturing method in the embodiment of the present invention is suitable for manufacturing articles such as devices (semiconductor devices, magnetic storage media, liquid crystal display elements, etc.), for example. Such a manufacturing method includes a step of exposing a substrate coated with a photosensitive agent using an exposure apparatus 100 or 100A, and a step of developing the exposed substrate. Such a manufacturing method may include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article in the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

  As mentioned above, although preferable embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, the present invention can be applied to a combination of the first embodiment and the second embodiment. In other words, both measurements may be performed by including both a measurement unit that measures the focus state of light from the projection optical system and a measurement unit that measures the positional deviation of the substrate via the projection optical system.

100, 100A: Exposure apparatus 7: Control unit 12: Acquisition unit 14: Setting unit 15A, 15B: Alignment measurement system

Claims (11)

In an exposure apparatus that transfers a mask pattern to a substrate via a projection optical system, the measurement method measures the focus state of light from the projection optical system or the positional deviation of the substrate via the projection optical system. And
A first step of setting a target accuracy of the measurement;
A second step of determining the accuracy of the measurement when the measurement is performed once based on the state of the projection optical system;
A third step of determining the number of times of measurement necessary to satisfy the target accuracy based on the accuracy of the measurement obtained in the second step, and performing the measurement for the determined number of times;
A measurement method characterized by comprising:   2. The accuracy of the measurement when performing the measurement is obtained in the second step using information indicating a relationship between the state of the projection optical system and the accuracy of the measurement. Measurement method.   The measurement method according to claim 1, wherein the second step includes a step of acquiring a state of the projection optical system. In the third step, when the target accuracy is AT ₁ and the accuracy obtained in the second step is A ₁ , the number of times of measurement N ₁ is determined according to N ₁ = (A ₁ / AT ₁ ) ^2. The measurement method according to any one of claims 1 to 3, wherein:   The measurement method according to claim 1, wherein the state of the projection optical system includes at least one of temperature, humidity, and pressure in the projection optical system.   6. The position shift of the substrate includes a position shift between the mask and the substrate or a position shift of the substrate from a reference position. 6. Measurement method.   The measurement method according to claim 1, wherein a value obtained by averaging the measurement results obtained by performing the measurement for the determined number of times is obtained. An exposure apparatus for transferring a mask pattern onto a substrate,
A measuring unit for measuring a focus state of light from the projection optical system;
An acquisition unit for acquiring the state of the projection optical system;
Based on the state of the projection optical system acquired by the acquisition unit, the measurement unit is required to obtain the accuracy of one measurement of the focus state by the measurement unit, and the measurement accuracy is required to satisfy the target accuracy. Determining the number of times the focus state is measured by the control unit, and controlling the measurement unit to perform the measurement for the determined number of times,
An exposure apparatus comprising: An exposure apparatus for transferring a mask pattern onto a substrate,
A measurement unit that measures the positional deviation of the substrate via the projection optical system;
An acquisition unit for acquiring the state of the projection optical system;
Based on the state of the projection optical system acquired by the acquisition unit, the accuracy of one measurement of the positional deviation of the substrate by the measurement unit is obtained, and the accuracy of the measurement is necessary to satisfy the target accuracy A control unit that determines the number of measurement of the positional deviation of the substrate by the measurement unit, and controls the measurement unit to perform the measurement of the determined number of times;
An exposure apparatus comprising:   The exposure apparatus according to claim 8, further comprising a setting unit that sets the target accuracy in accordance with a user input. A step of exposing the substrate using the exposure apparatus according to any one of claims 8 to 10,
Developing the exposed substrate;
A method for producing an article comprising:

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