Measurement apparatus, lithography apparatus, and production method of article

Abstract

To provide a measurement apparatus advantageous for measuring a position of a pattern provided on an object.SOLUTION: There is provided a measurement apparatus for measuring positions of a first pattern and a second pattern provided on an object including: an imaging part having an imaging element in which a plurality of pixels are arrayed in two directions, for imaging the first pattern in a first imaging region of the imaging element, and imaging the second pattern in a second imaging region of the imaging element different from the first imaging region; and a control part for obtaining positions of the first pattern and the second pattern on the basis of the image by causing the imaging part to image an image containing the first pattern and the second pattern in a state of forming the images of the first pattern and the second pattern by distinguishing a sensibility of the first imaging region from a sensibility of the second imaging region each other so that a relative ratio of a strength of a detection signal of the first pattern imaged in the first imaging region and a strength of a detection signal of the second pattern imaged in the second imaging region fall into an allowable range.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a metrology apparatus, a lithographic apparatus and a method for manufacturing an article. [Background technology]

[0002] In recent years, semiconductor integrated circuits have become highly integrated and finer, and the line width of the pattern to be formed on the substrate has become very small, so that further finer patterning is required for the lithography process that forms the pattern (resist pattern) on the substrate. Step-and-repeat and step-and-scan exposure devices used in the lithography process form a pattern on the substrate by imaging light (exposure light) from the original onto a predetermined position on the substrate via a projection optical system. Therefore, in order to meet the demand for finer patterns, it is important to align the relative positions of the original and the substrate with high accuracy. In addition, as the patterns become finer, it is also important to measure the patterns formed on different layers on the substrate with high accuracy when measuring the overlay error of the patterns formed on the substrate.

[0003] In exposure apparatuses, generally, prior to exposure, global alignment is performed in which the positions of alignment marks provided corresponding to the shot areas on a substrate are measured, and the arrangement (grid arrangement) of the shot areas is obtained from the measurement results to perform alignment. In global alignment, in order to achieve both improved alignment accuracy and reduced measurement time, a technology has been proposed in which a readout area is set in the field of view of an imaging element and the position of the alignment mark is measured (see Patent Document 1).

[0004] Patent Document 1 discloses a technique for measuring the position of an alignment mark composed of multiple mark elements by changing the settings of the resolution and readout area of ​​an imaging element. This technique makes it possible to measure the alignment mark on a substrate quickly and with high accuracy by sequentially performing low-resolution, wide-range mark detection and high-resolution, narrow-range mark detection.

[0005] In overlay measurement, which measures the overlay error of different layers formed on a substrate, a pattern formed on a lower layer and a pattern formed on an upper layer are simultaneously observed to measure the relative positions of the patterns on the upper and lower layers. In overlay measurement, in order to achieve both improved measurement accuracy and reduced measurement time, a technology has been proposed in which a processing region is set for an output image from an imaging element to obtain relative position information of the patterns (see Patent Document 2).

[0006] Patent Document 2 discloses a technique for setting multiple processing regions for multiple patterns in an output image from an imaging element. This technique makes it possible to measure the relative positions of multiple patterns formed on different layers on a substrate at high speed and with high accuracy by generating a signal corresponding to the pattern in each of the multiple processing regions. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5550253 [Patent Document 2] Patent No. 5180419 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in conventional techniques, when differences in reflectivity on the substrate cause differences in the intensity of detected light between patterns on the same layer or different layers, there is a problem that this can lead to reduced measurement accuracy and measurement errors, resulting in reduced productivity.

[0009] The present invention has been made in consideration of the problems with the conventional technology, and has an exemplary object to provide a measurement apparatus that is advantageous for measuring the position of a pattern provided on an object. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, a measuring device as one aspect of the present invention is a measuring device that measures the positions of a first pattern and a second pattern provided on an object, the measuring device having an imaging element in which a plurality of pixels are arranged in two directions, an imaging unit that images the first pattern in a first imaging area of ​​the imaging element and images the second pattern in a second imaging area of ​​the imaging element different from the first imaging area, and a control unit that makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other so that a relative ratio between an intensity of a detection signal of the first pattern imaged in the first imaging area and an intensity of a detection signal of the second pattern imaged in the second imaging area falls within an acceptable range, causes the imaging unit to image an image including the first pattern and the second pattern when images of the first pattern and the second pattern are formed on the imaging element, and determines the positions of the first pattern and the second pattern based on the images.

[0011] Further objects or other aspects of the present invention will become apparent from the following description of the embodiments with reference to the accompanying drawings. Effect of the Invention

[0012] According to the present invention, for example, a measurement apparatus that is advantageous for measuring the position of a pattern provided on an object can be provided. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram for explaining a measurement device in a first embodiment of the present invention. [Diagram 2] 11A and 11B are diagrams for explaining a measurement process for measuring an overlay error. [Diagram 3] FIG. 1 is a diagram for explaining a problem in the conventional technology. [Figure 4] 5A to 5C are diagrams for explaining a measurement process for measuring an overlay error in the first embodiment. [Diagram 5]5 is a flowchart for explaining a sequence of a measurement process for measuring an overlay error in the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining a specific method of calculating the sensitivity correction value in S154 shown in FIG. 5. [Figure 7] FIG. 11 is a view for explaining an exposure apparatus in a second embodiment of the present invention. [Figure 8] 1 is a flowchart for explaining a sequence of an exposure process for exposing a substrate. [Figure 9] 13A to 13C are diagrams for explaining a measurement process for measuring the position of a mark in the second embodiment. [Figure 10] 13A to 13C are diagrams for explaining a measurement process for measuring the position of a mark in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 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.

[0015] First Embodiment Fig. 1(a) is a schematic diagram showing the configuration of a measurement apparatus 100 according to one aspect of the present invention. The measurement apparatus 100 is an overlay measurement apparatus (overlay inspection apparatus) that measures an overlay error on a substrate 73, specifically, the relative positions of a plurality of patterns provided on different layers on the substrate (on an object). As shown in Fig. 1(a), the measurement apparatus 100 includes a substrate stage WS that holds the substrate 73, a measurement unit 50, and a control unit 1100.

[0016] The substrate 73 is an object for which an overlay error is measured by the measuring device 100. The substrate 73 is, for example, a substrate used for manufacturing devices such as semiconductor elements and liquid crystal display elements, and specifically includes a wafer, a liquid crystal substrate, other substrates to be processed, and the like.

[0017] The substrate stage WS holds the substrate 73 via a substrate chuck (not shown) and is connected to a substrate driving mechanism (not shown). The substrate driving mechanism includes a linear motor and the like, and can move the substrate 73 held by the substrate stage WS by driving the substrate stage WS in the X-axis direction, the Y-axis direction, the Z-axis direction, and the rotational direction of each axis. In addition, the position of the substrate stage WS is monitored by, for example, a six-axis laser interferometer 81, and the substrate stage WS is driven to a predetermined position under the control of the control unit 1100.

[0018] The control unit 1100 is configured with a computer (information processing device) including a CPU, a memory, etc., and, for example, controls each unit of the measuring device 100 in accordance with a program stored in a storage unit to operate the measuring device 100. In this embodiment, the control unit 1100 controls the measurement processing in the measuring device 200 and the correction processing (arithmetic processing) of the measurement values ​​obtained by the measuring device 200.

[0019] The configuration of the measurement unit 50 will be described with reference to Fig. 1(b). The measurement unit 50 includes an illumination system that illuminates the substrate 73 with light from the light source 61, and an imaging system (detection system) that images the light from a measurement pattern 72 provided on the substrate 73 on an imaging element 75 (forming an image of the measurement pattern 72). The imaging element 75 includes a plurality of pixels that detect the light from the measurement pattern 72, and functions as an imaging unit that forms an imaging area for imaging the measurement pattern 72 using the plurality of pixels. Here, the measurement pattern 72 is a pattern for measuring an overlay error on the substrate 73.

[0020] 1(b), light from a light source 61 is guided through illumination optical systems 62 and 63 to an illumination aperture stop 64 arranged at a position optically conjugate with a substrate 73. The light beam diameter at the illumination aperture stop 64 is smaller than that at the light source 61. The light passing through the illumination aperture stop 64 is guided to a polarizing beam splitter 68 through an illumination optical system 66, a mirror M2, and a relay lens 67. The polarizing beam splitter 68 transmits P-polarized light parallel to the Y direction and reflects S-polarized light parallel to the X direction. The P-polarized light passing through the polarizing beam splitter 68 passes through an aperture stop 69, a λ / 4 plate 70, and is converted into circularly polarized light, and passes through an objective optical system 71 to Kohler-illuminate a measurement pattern 72 provided on a substrate 73.

[0021] The illumination system may be provided with a light amount adjustment unit (not shown) and a wavelength adjustment unit (not shown). For example, by controlling a light amount adjustment unit capable of switching between a plurality of ND filters having different transmittances for the light from the light source 61, the intensity of the light illuminating the substrate 73 can be adjusted with high precision. In addition, by controlling a wavelength adjustment unit capable of switching between a plurality of wavelength filters having different wavelength characteristics of light transmitted through the light from the light source 61, the wavelength of the light illuminating the substrate 73 can be adjusted (changed).

[0022] Light reflected, diffracted, and scattered by measurement pattern 72 provided on substrate 73 passes through objective optical system 71, passes through λ / 4 plate 70, is converted from circularly polarized light to S-polarized light, and is guided to aperture stop 69. Here, the polarization state of the light from measurement pattern 72 becomes circularly polarized in the opposite direction to the circularly polarized light illuminating measurement pattern 72. Therefore, if the polarization state of the light illuminating measurement pattern 72 is right-handed circularly polarized, the polarization state of the light from measurement pattern 72 becomes left-handed circularly polarized. The light that passed through aperture stop 69 is reflected by polarizing beam splitter 68, and is guided to image sensor 75 via imaging optical system 74.

[0023] Thus, in the measurement unit 50, the optical path of the light illuminating the substrate 73 is separated from the optical path of the light from the substrate 73 by the polarizing beam splitter 68, and an image of the measurement pattern 72 provided on the substrate 73 is formed on the image sensor 75. Then, the control unit 1100 acquires the positions of the pattern elements that make up the measurement pattern 72 and the position of the measurement pattern 72, based on position information of the substrate stage WS obtained by the laser interferometer 81 and the waveform of the detection signal obtained by detecting the image of the measurement pattern 72.

[0024] In the imaging system of the measurement unit 50, a detection aperture stop may be configured by arranging multiple lenses between the polarizing beam splitter 68 and the image sensor 75. Also, the illumination aperture stop 64 and the detection aperture stop may each be provided with multiple aperture stops that can set different numerical apertures for the illumination system and the imaging system, respectively, and these multiple aperture stops may be made switchable. This makes it possible to adjust the σ value, which is a coefficient that represents the ratio between the numerical aperture of the illumination system and the numerical aperture of the imaging system.

[0025] 1(c) is a diagram showing an example of the configuration of a measurement pattern 72 provided on a substrate 73. In this embodiment, the substrate 73 is a substrate composed of three layers: a bottom layer 73B, a first layer 73L, and a second layer 73U. The measurement pattern 72 is composed of a first pattern P1 provided on the first layer 73L, and a second pattern P2 provided on the second layer 73U. The first pattern P1 includes four pattern elements P1a, P1b, P1c, and P1d, and the second pattern P2 includes four pattern elements P2a, P2b, P2c, and P2d.

[0026] The measurement device 100 detects the measurement pattern 72, specifically, the light (reflected light and scattered light) from each of the first pattern P1 and the second pattern P2, using the image sensor 75 (measurement unit 50). A method for detecting the light from the measurement pattern 72 may be, for example, dark-field detection, in which the illumination aperture stop 64 and the detection aperture stop (respective numerical apertures of the illumination system and the imaging system) are controlled to block the zeroth-order diffracted light from the measurement pattern 72 and detect only high-order diffracted light and scattered light.

[0027] 2(a) and 2(b), a measurement process for measuring the overlay error on the substrate 73, i.e., a measurement process for measuring the relative positions of the first pattern P1 and the second pattern P2 that constitute the measurement pattern 72, will be described as a general operation of the measurement apparatus 100.

[0028] Fig. 2(a) is a diagram showing an image of the measurement pattern 72 formed on the imaging region (imaging surface or detection surface) of the imaging element 75 shown in Fig. 1(b). The imaging element 75 is a two-dimensional imaging element having an imaging region made up of a plurality of pixels arranged in the X and Y directions. The control unit 1100 generates detection signals including waveforms corresponding to the first pattern P1 and the second pattern P2, respectively, based on the output (captured image) from the imaging element 75.

[0029] Fig. 2(b) is a diagram showing an example of a detection signal SW generated based on an image obtained by capturing an image of the measurement pattern 72 shown in Fig. 2(a) with the imaging element 75. The detection signal SW is generated by integrating the signal intensity of each pixel of the imaging element 75 in the Y direction for the captured image including the image of the measurement pattern 72 shown in Fig. 2(a). Note that with regard to the integration of the signal intensity of each pixel of the imaging element 75, it is preferable that the number of pixels to be integrated is set based on the dimensional information of the measurement pattern 72.

[0030] 2(b), a waveform S1 included in the detection signal SW corresponds to (a change in) the signal intensity of the first pattern P1, and a waveform S2 included in the detection signal SW corresponds to (a change in) the signal intensity of the second pattern P2. The control unit 1100 obtains a measurement value X1 indicating the center position of the first pattern P1 from the waveform S1, and obtains a measurement value X2 indicating the center position of the second pattern P2 from the waveform S2. Then, for example, by obtaining the difference between the measurement value X1 and the measurement value X2, the relative positional deviation in the X direction between the first pattern P1 and the second pattern P2 is obtained.

[0031] When measuring the relative positional shift in the Y direction as the overlay error, a measurement pattern may be used that is configured with a first pattern and a second pattern that have a longitudinal direction equal to the X direction and include a plurality of pattern elements arranged along the Y direction. Then, for a captured image that includes an image of such a measurement pattern, a detection signal is generated by integrating the signal intensity of each pixel in the X direction, and the relative positional shift in the Y direction is obtained from the difference between the measurement values ​​of the first pattern and the second pattern.

[0032] Here, when there is a large difference in reflectance between the first layer 73L and the second layer 73U in the substrate 73, a difference occurs between the light intensity (intensity of detected light) corresponding to the first pattern P1 and the light intensity corresponding to the second pattern P2 detected by the imaging element 75. Below, a description is given of problems that arise when a difference occurs between the light intensity corresponding to the first pattern P1 and the light intensity corresponding to the second pattern P2 in the conventional technology, specifically, a decrease in measurement accuracy and a decrease in productivity due to measurement errors.

[0033] Fig. 3(a) is a diagram showing an image of measurement pattern 72, specifically, an image P13 of first pattern P1 and an image P23 of second pattern P2, formed on the imaging region of image sensor 75 when there is a large difference in reflectance between first layer 73L and second layer 73U. Fig. 3(b) is a diagram showing an example of detection signal SW30 generated based on an image obtained by imaging the image of measurement pattern 72 shown in Fig. 3(a) with image sensor 75.

[0034] 3(b), the waveform S130 included in the detection signal SW30 corresponds to (changes in) the signal intensity of the first pattern P1, and the waveform S230 included in the detection signal SW30 corresponds to (changes in) the signal intensity of the second pattern P2. As shown in FIG. 3(b), when the difference in reflectance between the first layer 73L and the second layer 73U is large and the signal intensity (waveform S130) of the first pattern P1 is low, the electrical noise relative to the signal intensity is relatively high in the waveform S130 compared to the waveform S230. In such a case, it is possible to obtain the measured value X230 indicating the center position of the second pattern P2 with high accuracy from the waveform S230, but it is difficult to obtain the measured value X130 indicating the center position of the first pattern P1 with high accuracy from the waveform S130.

[0035] Fig. 3(c) is a diagram showing an example of detection signal SW31 generated based on an image obtained by imaging measurement pattern 72 with imaging element 75 when the amount of light illuminating measurement pattern 72 is increased in order to increase the signal intensity of first pattern P1. Referring to Fig. 3(c), waveform S131 included in detection signal SW31 corresponds to (change in) the signal intensity of first pattern P1, and waveform S231 included in detection signal SW31 corresponds to (change in) the signal intensity of second pattern P2.

[0036] In the measurement device 100, it is possible to adjust the signal intensity from the measurement pattern 72 by controlling the light amount adjustment unit (ND filter) and the output of the light source 61 provided in the illumination system of the measurement unit 50, or by controlling the accumulation time of the image sensor 75. However, when the signal intensity of the entire observation field of the image sensor 75, i.e., the imaging area, is increased, the signal intensity in the waveform S131 becomes higher than the signal intensity in the waveform S130, but the signal intensity in the waveform S231 also becomes higher. As a result, when the signal intensity in the waveform S231 exceeds the level detectable by the image sensor 75, for example, when it becomes a saturation level, it becomes difficult to obtain the measurement value X230 indicating the center position of the second pattern P2 from the waveform S231 with high accuracy.

[0037] It is also conceivable that the measurement device 100 performs measurements multiple times by changing the amount of light illuminating the measurement pattern 72, and obtains the waveforms S131 and S230 from the first pattern P1 and the second pattern P2, respectively. This makes the signal strength of each of the waveforms S131 and S230 less than the saturation level of the image sensor 75. Therefore, it is possible to obtain the measurement value X130 indicating the center position of the first pattern P1 from the waveform S131 with high accuracy, and the measurement value X230 indicating the center position of the second pattern P2 from the waveform S231 with high accuracy. However, in this case, it is necessary to perform measurements multiple times by changing the amount of light illuminating the measurement pattern 72, which may lead to a decrease in productivity due to an increase in measurement time and a decrease in measurement accuracy due to the passage of time (change over time).

[0038] Therefore, in this embodiment, a technique is proposed that can obtain measurement values ​​indicating the respective center positions of the first pattern P1 and the second pattern P2 with high accuracy even when the difference in reflectance between the first layer 73L and the second layer 73U is large. Specifically, based on the position of the measurement pattern 72, at least two different imaging regions, for example, a first imaging region for imaging the first pattern P1 and a second imaging region for imaging the second pattern P2, are set in the imaging region of the imaging element 75. In addition, the imaging element 75 is adjusted so that the relative ratio between the intensity of the detection signal of the first pattern P1 generated based on the output from the first imaging region and the intensity of the detection signal of the second pattern P2 generated based on the output from the second imaging region falls within an allowable range. For example, the adjustment of the imaging element 75 is performed by setting the sensitivity of each of the multiple pixels of the imaging element 75. Then, based on the output from the imaging element 75 to which different sensitivities are set, the relative positions (overlay error) of the first pattern P1 and the second pattern P2 are obtained as the positions of the first pattern P1 and the second pattern P2.

[0039] 4(a) and 4(b), a measurement process for measuring an overlay error on a substrate 73, i.e., a measurement process for measuring the relative positions of a first pattern P1 and a second pattern P2 constituting a measurement pattern 72, in this embodiment will be described. FIG. 4(a) is a diagram showing an image of the measurement pattern 72 formed on the imaging region of the imaging element 75 when the difference in reflectance between the first layer 73L and the second layer 73U is large, specifically, an image P13 of the first pattern P1 and an image P23 of the second pattern P2. As shown in FIG. 4(a), the control unit 1100 sets a first imaging region R13 to include the image P13 of the first pattern P1 and a second imaging region R23 to include the image P23 of the second pattern P2 in the imaging region of the imaging element 75 based on the position of the measurement pattern 72. Next, the control unit 1100 obtains the signal intensity of the first pattern PT1 generated based on the output from the first imaging region R13 and the signal intensity of the second pattern PT2 generated based on the output from the second imaging region R23. Next, the control unit 1100 obtains sensitivity correction values ​​for the multiple pixels of the imaging element 75, specifically, for each of the first imaging region R13 and the second imaging region R23, so that the relative ratio between the signal intensity of the first pattern PT1 and the signal intensity of the second pattern PT2 falls within an allowable range. Then, the control unit 1100 sets different sensitivities for each of the first imaging region R13 and the second imaging region R23 of the imaging element 75 based on the sensitivity correction values.

[0040] FIG. 4(b) is a diagram showing an example of a detection signal SW3 generated based on an image obtained by capturing an image of the measurement pattern 72 shown in FIG. 4(a) with an image sensor 75 having different sensitivities set for the first imaging region R13 and the second imaging region R23. Referring to FIG. 4(b), a waveform S13 included in the detection signal SW3 corresponds to (changes in) the signal intensity of the first pattern P1, and a waveform S23 included in the detection signal SW3 corresponds to (changes in) the signal intensity of the second pattern P2. In this embodiment, a higher sensitivity is set for the pixels included in the first imaging region R13 than for the pixels included in the second imaging region R23, thereby making it possible to avoid a decrease in signal intensity in the waveform S13 and saturation of signal intensity in the waveform S23. This makes it possible to obtain a measurement value X13 indicating the center position of the first pattern P1 from the waveform S13 with high accuracy, and a measurement value X23 indicating the center position of the second pattern P2 from the waveform S23 with high accuracy.

[0041] Here, there is a difference in the rate of increase in signal strength and noise with respect to the increase in the sensitivity of the image sensor. Specifically, the signal strength increases in proportion to the increase in the sensitivity of the image sensor, but the noise amplification changes according to the set value of the sensitivity of the image sensor. The reason for this is that it includes shot noise that is not affected by the sensitivity of the image sensor. In general, noise N is expressed by the following formula (1) using read noise Nr and dark current noise Nd that change according to the sensitivity of the image sensor, and shot noise Ns that is not affected by the sensitivity of the image sensor.

[0042]

number

[0043] Therefore, by setting the sensitivity of the imaging element so as to avoid a decrease in measurement accuracy due to increased noise while achieving a detectable signal strength (level) in the imaging element, the measurement value X13 can be obtained with higher accuracy than the measurement value X130.

[0044] 5, a description will be given of a measurement process sequence for measuring an overlay error in this embodiment, that is, the relative position between the first pattern P1 and the second pattern P2 constituting the measurement pattern 72. As described above, the measurement process is performed by the control unit 1100 comprehensively controlling each unit of the measurement apparatus 100.

[0045] When the measurement process for measuring the overlay error is started, first, the substrate stage WS holding the substrate 73 is positioned so that an image of the measurement pattern 72 is formed in the imaging area of ​​the imaging element 75 of the measurement unit 50. Regarding the position of the substrate 73 in the Z direction relative to the measurement unit 50, for example, the signal intensity of at least one pattern constituting the measurement pattern 72 may be obtained, and the substrate stage WS holding the substrate 73 may be positioned so that the signal intensity and its change are equal to or greater than a target value. Alternatively, the signal intensity of each of the first pattern PT1 and the second pattern PT2 constituting the measurement pattern 72 may be obtained, and the substrate stage WS holding the substrate 73 may be positioned so that the signal intensity and its change are equal to or greater than a target value.

[0046] In S151, information (position information) on the position of measurement pattern 72 provided on substrate 73 is acquired. In this embodiment, the position of measurement pattern 72 provided on substrate 73 is roughly measured to acquire the position information of measurement pattern 72. The rough measurement in S151 is performed at a lower resolution in a wider measurement range than the precise measurement in S156 described later. Therefore, the rough measurement in S151 and the precise measurement in S156 are defined, for example, as follows. The rough measurement in S151 is a measurement process (first measurement process) that measures the position of measurement pattern 72 at a first resolution and in a first measurement range. The precise measurement in S156 is a measurement process (second measurement process) that measures the position of measurement pattern 72 at a second resolution higher than the first resolution and in a second measurement range narrower than the first measurement range. Here, the resolution of the position information means the size of a pixel with respect to the imaging area of ​​image sensor 75 on the substrate and the gradation of an image acquired by image sensor 75. In the rough measurement, the increase in the transfer time in the imaging element 75 and the calculation processing time in the control unit 1100 can be suppressed, and the position information of the measurement pattern 72 can be acquired.

[0047] Specifically, in S151, the position of the measurement pattern 72 is obtained by determining a change in signal intensity of the measurement pattern 72 based on an image obtained by capturing an image of the measurement pattern 72 with the image sensor 75, i.e., an image obtained by rough measurement. The position of the measurement pattern 72 may also be obtained based on an image obtained by rough measurement and a design value of the measurement pattern 72 that is registered in advance. Furthermore, as another method, the position of the measurement pattern 72 may be obtained based on the position of the substrate 73 when it is transported to the substrate stage WS, which is obtained by a substrate position measuring device (not shown) different from the measurement unit 50 (measuring device 100).

[0048] Furthermore, in S151, in addition to roughly measuring the position of measurement pattern 72, the wavelength and σ value of the light illuminating measurement pattern 72 may be adjusted to setting values ​​suitable for the precise measurement in S155, i.e., setting values ​​that enable highly accurate measurement of the position of measurement pattern 72. Note that the setting values ​​related to the wavelength and σ value of the light illuminating measurement pattern 72 may be determined in advance based on, for example, the measurement results of measurement pattern 72 and information related to the structure and physical properties of substrate 73.

[0049] In S152, based on the position information of the measurement pattern 72 acquired in S151, a plurality of different imaging regions are set in the imaging region of the imaging element 75. Specifically, imaging regions are set for each of the first pattern P1 and the second pattern PT2 based on the position information of the measurement pattern 72 in the imaging region of the imaging element 75. For example, as shown in Fig. 4(a), a first imaging region R13 is set in the imaging region of the imaging element 75 so as to include an image P13 of the first pattern P1, and a second imaging region R23 is set so as to include an image P23 of the second pattern P2.

[0050] In the imaging area of ​​the imaging element 75, the multiple imaging areas different from each other are set based on the lengths of the measurement direction and non-measurement direction of the pattern to be measured. For example, the imaging area may be set wider than the length of the measurement direction of a pattern composed of multiple pattern elements to obtain signal intensities in a pattern area including a pattern and a non-pattern area not including a pattern. Also, the imaging area may be set equal to or wider than the length of the non-measurement direction of the pattern to obtain signal intensities in the non-measurement direction of the pattern. This makes it possible to set the sensitivity of the imaging area of ​​the imaging element 75 with respect to the position of the pattern with high accuracy. The measurement direction of the pattern is the direction in which the pattern elements constituting the pattern are arranged, and the non-measurement direction of the pattern is the direction perpendicular to the arrangement direction of the pattern elements constituting the pattern. For example, in the measurement pattern 72 including the first pattern P1 and the second pattern P2, the X direction in which the pattern elements P1a to P1d and P2a to P2d are arranged is the measurement direction, and the Y direction perpendicular to the X direction is the non-measurement direction.

[0051] In S153, information (signal intensity information) on the signal intensity in each of the multiple imaging regions different from each other set in the imaging element 75 in S152 is acquired. Specifically, signal intensity information indicating (changes in) the signal intensity of the first pattern PT1 is acquired based on the output from the first imaging region R13. Similarly, signal intensity information indicating (changes in) the signal intensity of the second pattern PT2 is acquired based on the output from the second imaging region R23. Note that the signal intensity information may be the maximum value of the signal intensity of each of the first pattern PT1 and the second pattern PT2 in the detection signal generated based on the output from the imaging element 75, or the average value thereof. As a method for acquiring signal intensity information from an image acquired by the imaging element 75, for example, there is a method of averaging the signal intensity at each pixel in the Y direction, which is the non-measurement direction, for the first pattern PT1, to obtain the change in signal intensity in the X direction, which is the measurement direction. With such a method, it is possible to acquire signal intensity information of each of the first pattern PT1 and the second pattern PT2 based on the output from each of the first imaging region R13 and the second imaging region R23.

[0052] In S154, a sensitivity correction value is calculated for each of a plurality of different imaging regions (the first imaging region R13 and the second imaging region R23) of the image sensor 75 based on the signal intensity information in each of the imaging regions acquired in S153. Note that a specific method for calculating the sensitivity correction value will be described in detail later.

[0053] In S155, the sensitivity is set based on the sensitivity correction value calculated in S154 for each of the multiple imaging regions (first imaging region R13 and second imaging region R23) of the image sensor 75 that are different from each other. For example, if the sensitivity set by default in the image sensor is the first sensitivity, the second sensitivity expressed as the product of the first sensitivity and the sensitivity correction value is set for each of the multiple imaging regions of the image sensor 75 that are different from each other.

[0054] In S156, position information of the measurement pattern 72 provided on the substrate 73 is acquired using the image sensor 75 in which the sensitivity is set in each of the multiple imaging regions different from each other in S155. In this embodiment, the position information of the measurement pattern 72 is acquired by precisely measuring the position of the measurement pattern 72 provided on the substrate 73. The precise measurement in S156 is performed with high resolution in a narrower measurement range (i.e., the measurement range is limited to a predetermined range) compared to the rough measurement in S151. Specifically, a detection signal SW3 is generated based on an image obtained by capturing an image of the measurement pattern 72 using the image sensor 75 in which different sensitivities are set in the first imaging region R13 and the second imaging region R23. Then, a waveform S13 corresponding to (change in) the signal intensity of the first pattern P1 and a waveform S23 corresponding to (change in) the signal intensity of the second pattern P2 are extracted from the detection signal SW3. In addition, detection signals may be generated for each of the first imaging region R13 and the second imaging region R23, and a waveform corresponding to the signal intensity of the first pattern P1 and a waveform corresponding to the signal intensity of the second pattern P2 may be obtained from each detection signal.

[0055] In S157, the overlay error is calculated based on the position information of measurement pattern 72 acquired in S156. Specifically, a measured value X13 indicating the center position of first pattern P1 is obtained from waveform S13, and a measured value X23 indicating the center position of second pattern P2 is obtained from waveform S23. Then, the relative position (deviation) between first pattern P1 and second pattern P2, which is the difference between measured value X13 and measured value X23, is calculated as the overlay error.

[0056] A specific method of calculating the sensitivity correction value in S154 will be described with reference to Fig. 6(a) and Fig. 6(b). Fig. 6(a) is a diagram showing the signal intensities of the first pattern P1 and the second pattern P2 obtained from the imaging element 75 before setting the sensitivity to each of the multiple imaging regions different from each other in S155. In Fig. 6(a), I13 indicates the signal intensity of the first pattern P1, and I23 indicates the signal intensity of the second pattern P2. Here, the signal intensity ratio (Brightness) to the maximum detected light amount of the imaging element 75 will be described for example when the signal intensity I13 is 20% and the signal intensity I23 is 80%. In this case, the relative ratio between the signal intensity of the first pattern P1 and the signal intensity of the second pattern P2 is calculated to be 0.25 from the ratio of the low signal intensity I13 to the high signal intensity I23. Here, if the allowable range of the relative ratio of signal strengths is set to 0.5 or more and 1.0 or less, the relative ratio between signal strength I13 and signal strength I23 does not fall within the allowable range.

[0057] Therefore, in this embodiment, a sensitivity correction value for each of the first imaging region R13 and the second imaging region R23 is calculated so that the relative ratio between the signal intensity of the first pattern P1 and the signal intensity of the second pattern P2 falls within an allowable range. Specifically, a sensitivity correction value for a low signal intensity I13 is calculated based on a high signal intensity I23 and a target value that satisfies the allowable range of the relative ratio of the signal intensity. For example, the target value of the signal intensity of the first pattern P1 is calculated as 40% from the product of the signal intensity I23 (80%) and the target value of the relative ratio of the signal intensity (for example, 0.5). As a result, the sensitivity correction value for the first imaging region R13 is calculated as 2.0 from the quotient of the target value of the signal intensity of the first pattern P1 (40%) and the signal intensity I13 (20%). Similarly to the first imaging region R13, a sensitivity correction value is calculated for the second imaging region R23 so that the relative ratio of the signal intensity falls within an allowable range. When the signal intensity ratio with respect to the maximum detectable light amount of the imaging element 75 is not changed, the sensitivity correction value for the second imaging region R23 is calculated as 1.0.

[0058] Based on the sensitivity correction value calculated in this manner, the sensitivity is set individually for each of the first imaging region R13 and the second imaging region R23 in the imaging element 75. For example, consider a case where the sensitivity of both the first imaging region R13 and the second imaging region R23 in the imaging element 75 when the signal intensities I12 and I13 shown in Fig. 6(a) are obtained is 1.0. In this case, based on the product with the sensitivity correction value described above, the sensitivity of the first imaging region R13 is set to 2.0, and the sensitivity of the second imaging region R23 is set to 1.0.

[0059] FIG. 6(b) is a diagram showing the signal intensities of the first pattern P1 and the second pattern P2 obtained from the imaging element 75 after the sensitivity is set for each of the multiple imaging regions different from each other in S155. In FIG. 6(b), I14 indicates the signal intensity of the first pattern P1, and I24 indicates the signal intensity of the second pattern P2. Since the sensitivity of the first imaging region R13 is set to 2.0 and the sensitivity of the second imaging region R23 is set to 1.0, as shown in FIG. 6(b), the signal intensities I14 and I24 are the same intensity. In addition, the relative ratio of the signal intensities I14 and I24 is increased to 0.5 compared to the relative ratio of the signal intensities I13 and I23 shown in FIG. 6(a), which is 0.25. As a result, the relative ratio of the signal intensities I14 and I24 falls within the allowable range (0.5 or more and 1.0 or less), and it is possible to obtain the relative position of the first pattern P1 and the second pattern P2 with high accuracy.

[0060] It is preferable that the sensitivity for each of the different imaging regions in the image sensor 75 is set by adjusting the digital gain of the image sensor 75. For example, when the sensitivity is set by adjusting the accumulation time of the image sensor 75, there is a possibility that an error due to a change in the position of the substrate stage WS will be included in the measurement values ​​of the first pattern P1 and the second pattern P2 due to the difference in accumulation time. This will cause a decrease in the measurement accuracy of the relative positions of the first pattern P1 and the second pattern P2.

[0061] Moreover, it is preferable that the digital gain (sensitivity) set in at least one of the multiple imaging regions different from each other in the imaging element 75 is 1. The reason for this is that as the sensitivity value set in the imaging element 75 increases, there is a possibility that the measurement accuracy will decrease due to an increase in noise.

[0062] In order to set the digital gain to 1 for at least one of the multiple imaging regions different from each other in the image sensor 75, signal intensity information may be acquired in S153 with the sensitivity of the image sensor 75 set to 1. For example, the signal intensity of the second pattern P2 having a high signal intensity ratio to the maximum detected light amount of the image sensor 75 is set to a level detectable by the image sensor 75 by adjusting the light amount in the illumination system of the measurement unit 50, controlling the output of the light source 61, controlling the accumulation time of the image sensor 75, etc. Then, in S155, the sensitivity is set for each of the multiple imaging regions different from each other in the image sensor 75 based on the sensitivity correction value calculated in S154. At this time, the sensitivity correction value for the second imaging region R23 corresponding to the second pattern P2 is set to 1.0, and the signal intensity of the first pattern P1 having a low signal intensity ratio to the maximum detected light amount of the image sensor 75 is amplified. As a result, the sensitivity of the second imaging region R23 corresponding to the second pattern P2 can be set to 1, thereby avoiding a decrease in measurement accuracy due to increased noise and making it possible to determine the relative position between the first pattern P1 and the second pattern P2 with high accuracy.

[0063] In this embodiment, the measurement process for measuring the relative position between the first pattern P1 and the second pattern P2 in the measurement device 100 has been described, but the present invention is not limited thereto. For example, the measurement device 100 can also measure the relative positions of three or more different patterns. Specifically, a first imaging region, a second imaging region, and a third imaging region are set for the first pattern, the second pattern, and the third pattern, respectively. Next, based on the signal strengths obtained from the first imaging region, the second imaging region, and the third imaging region, sensitivity correction values ​​for the first imaging region, the second imaging region, and the third imaging region are calculated. Then, based on the sensitivity correction values, sensitivity is set individually for the first imaging region, the second imaging region, and the third imaging region. This makes it possible to obtain the relative positions (shifts) between the first pattern, the second pattern, and the third pattern with high accuracy.

[0064] According to this embodiment, even if there is a difference in the intensity of the detection light between the patterns in different layers on the substrate, the relative positions between the patterns can be measured at high speed and with high accuracy by setting different sensitivities for the multiple imaging regions corresponding to each pattern. In addition, by setting different pixel sensitivities in the imaging element, instead of the accumulation time, it is possible to avoid a decrease in productivity due to multiple measurements. Furthermore, by setting different sensitivities to the pixels of the imaging element, instead of the captured image output from the imaging element, it is possible to measure the relative positions of the multiple patterns with high accuracy while avoiding a decrease in measurement accuracy, even if the intensity of the detection light from the multiple patterns is different. Therefore, it is possible to provide a measurement device capable of measuring the relative positions of the multiple patterns on the substrate at high speed and with high accuracy.

[0065] <Second embodiment> 7(a) is a schematic diagram showing the configuration of the exposure apparatus EXA. The exposure apparatus EXA is a lithography apparatus used in a lithography process, which is a manufacturing process for devices such as semiconductor elements and liquid crystal display elements, and forms a pattern on a substrate 83. The exposure apparatus EXA exposes the substrate 83 through a reticle 31, which is an original, and transfers the pattern of the reticle 31 onto the substrate 83. In this embodiment, the exposure apparatus EXA employs a step-and-scan method, but it is also possible to employ a step-and-repeat method or other exposure methods.

[0066] As shown in FIG. 7(a), the exposure apparatus EXA has an illumination optical system 801, a reticle stage RS that holds a reticle 31, a projection optical system 32, a substrate stage WS that holds a substrate 83, a position measurement device 200, and a control unit 1200.

[0067] The illumination optical system 801 is an optical system that illuminates an illuminated surface using light from a light source unit 800. The light source unit 800 includes, for example, a laser. The laser includes an ArF excimer laser with a wavelength of about 193 nm, a KrF excimer laser with a wavelength of about 248 nm, and the like, but the type of light source is not limited to an excimer laser. For example, the light source unit 800 may use, as a light source, an F2 laser with a wavelength of about 157 nm or an EUV (Extreme ultraviolet) with a wavelength of 20 nm or less.

[0068] In this embodiment, the illumination optical system 801 shapes the light from the light source unit 800 into a slit light having a predetermined shape optimal for exposure, and illuminates the reticle 31. The illumination optical system 801 has a function of uniformly illuminating the reticle 31 and a function of polarized illumination. The illumination optical system 801 includes, for example, a lens, a mirror, an optical integrator, an aperture, etc., and is configured by arranging a condenser lens, a fly's-eye lens, an aperture aperture, a condenser lens, a slit, and an imaging optical system in this order.

[0069] The reticle 31 is made of, for example, quartz. On the reticle 31, a pattern (circuit pattern) to be transferred onto the substrate 83 is formed.

[0070] The reticle stage RS holds the reticle 31 via a reticle chuck (not shown) and is connected to a reticle drive mechanism (not shown). The reticle drive mechanism includes a linear motor and the like, and is capable of moving the reticle stage RS in the X-axis, Y-axis, Z-axis directions and in the rotational directions about each axis, thereby moving the reticle 31 held by the reticle stage RS. The position of the reticle 31 is measured by a reticle position measurement unit (not shown) of an oblique light incidence system, and the reticle is positioned at a predetermined position via the reticle stage RS.

[0071] The projection optical system 32 has a function of forming an image of light from an object surface on an image surface. In this embodiment, the projection optical system 32 projects light (diffracted light) that has passed through the pattern of the reticle 31 onto the substrate 83, and forms an image of the pattern of the reticle 31 on the substrate. The projection optical system 32 may be an optical system made of multiple lens elements, an optical system including multiple lens elements and at least one concave mirror (catedioptric optical system), or an optical system including multiple lens elements and at least one diffractive optical element such as a kinoform.

[0072] A photoresist is applied to the substrate 83. The substrate 83 is an object to which the pattern of the reticle 31 is transferred, and includes a wafer, a liquid crystal substrate, other substrates to be processed, and the like.

[0073] The substrate stage WS holds the substrate 83 via a substrate chuck (not shown), and is connected to a substrate driving mechanism (not shown). The substrate driving mechanism includes a linear motor and the like, and is capable of moving the substrate stage WS in the X-axis direction, the Y-axis direction, the Z-axis direction, and the rotational direction of each axis, thereby moving the substrate 83 held by the substrate stage WS. In addition, a reference plate 39 is provided on the substrate stage WS.

[0074] The positions of the reticle stage RS and the substrate stage WS are monitored by, for example, a six-axis laser interferometer 91, and under the control of the control unit 1200, the reticle stage RS and the substrate stage WS are driven at a constant speed ratio.

[0075] The control unit 1200 is composed of a computer (information processing device) including a CPU, memory, etc., and generally controls each part of the exposure apparatus EXA according to a program stored in the storage unit, for example, to operate the exposure apparatus EXA. The control unit 1200 controls an exposure process in which the substrate 83 is exposed via the reticle 31 and the pattern of the reticle 31 is transferred to the substrate 83. In this embodiment, the control unit 1200 also controls the measurement process in the position measurement apparatus 200 and the correction process (arithmetic process) of the measurement value obtained by the position measurement apparatus 200. In this way, the control unit 1200 also functions as a part of the position measurement apparatus 200.

[0076] In the exposure apparatus EXA, light (diffracted light) that has passed through the reticle 31 is projected onto the substrate 83 via the projection optical system 32. The reticle 31 and the substrate 83 are disposed in an optically conjugate relationship. The pattern of the reticle 31 is transferred onto the substrate 83 by scanning the reticle 31 and the substrate 83 at a speed ratio that is the reduction magnification ratio of the projection optical system 32.

[0077] The position measurement device 200 is a measurement device that measures the position of an object. In this embodiment, the position measurement device 200 measures the position of a mark 82, such as an alignment mark, provided on a substrate 83. The configuration of the position measurement device 200 will be described below with reference to Fig. 7(b). However, since the position measurement device 200 shown in Fig. 7(b) has a similar configuration to the measurement unit 50 shown in Fig. 1(b), the description will be simplified here and only an overview will be described.

[0078] The position measurement device 200 includes an illumination system that illuminates the substrate 83 with light from a light source 161, and an imaging system (detection system) that images the light from the mark 82 on the substrate (forms an image of the mark 82). The illumination system includes illumination optical systems 162, 163, and 166, an illumination aperture stop 164, a mirror M20, a relay lens 167, a polarizing beam splitter 168, a λ / 4 plate 170, and an objective optical system 171. The imaging system includes the objective optical system 171, the λ / 4 plate 170, a detection aperture stop 169, a polarizing beam splitter 168, and an imaging optical system 174, and is configured to image the light from the mark 82 on the substrate onto an imaging element 175. The imaging element 175 includes a plurality of pixels that detect the light from the mark 82, and functions as an imaging unit that forms an imaging area for imaging the mark 82 using the plurality of pixels. The control unit 1200 acquires the position of the mark 82 on the substrate based on position information of the substrate stage WS obtained by the laser interferometer 91 and the waveform of a detection signal obtained by detecting the image of the mark 82 .

[0079] 8, a description will be given of a sequence of an exposure process in which the substrate 83 is exposed through the reticle 31 and the pattern of the reticle 31 is transferred onto the substrate 83. As described above, the exposure process is performed by the control unit 1200 comprehensively controlling each unit of the exposure apparatus EXA.

[0080] In S101, the substrate 83 is carried into the exposure apparatus EXA. In S102, the surface (height) of the substrate 83 is detected by a shape measuring device (not shown) to measure the surface shape of the entire area of ​​the substrate 83.

[0081] In S103, calibration is performed. Specifically, the substrate stage WS is driven so that the reference mark is positioned on the optical axis of the position measurement device 200 based on the design coordinate position of the reference mark provided on the reference plate 39 in the stage coordinate system. Next, the positional deviation of the reference mark with respect to the optical axis of the position measurement device 200 is measured, and the stage coordinate system is reset so that the origin of the stage coordinate system coincides with the optical axis of the position measurement device 200 based on the positional deviation. Next, the substrate stage WS is driven so that the reference mark is positioned on the optical axis of the exposure light based on the design positional relationship between the optical axis of the position measurement device 200 and the optical axis of the projection optical system 32. Then, the TTL (through-the-lens) measurement system measures the positional deviation of the reference mark with respect to the optical axis of the exposure light via the projection optical system 32.

[0082] In S104, the baseline between the optical axis of the position measurement device 200 and the optical axis of the projection optical system 32 is determined based on the result of the calibration in S103.

[0083] In S105, the position of the mark 82 provided on the substrate 83 is measured by the position measuring device 200.

[0084] In S106, global alignment is performed. Specifically, based on the measurement results in S105, the shift, magnification, and rotation are calculated for the arrangement of the shot areas of the substrate 83, and the regularity of the arrangement of the shot areas is obtained. Then, a correction coefficient is obtained from the regularity of the arrangement of the shot areas and the baseline, and the substrate 83 is aligned with the reticle 31 (exposure light) based on the correction coefficient.

[0085] In S107, the substrate 83 is exposed while scanning the reticle 31 and the substrate 83 in the scanning direction (Y direction). At this time, based on the surface shape of the substrate 83 measured by the shape measuring device, the substrate stage WS is driven in the Z direction and the tilt direction to sequentially align the surface of the substrate 83 with the imaging plane of the projection optical system 32.

[0086] In S108, it is determined whether exposure of all shot areas of substrate 83 is complete (i.e., whether there are any unexposed shot areas). If exposure of all shot areas of substrate 83 is not complete, the process proceeds to S107, and S107 and S108 are repeated until exposure of all shot areas is complete. On the other hand, if exposure of all shot areas of substrate 83 is complete, the process proceeds to S109, and substrate 83 is unloaded from exposure apparatus EXA.

[0087] In this embodiment, when measuring the position of the mark 82 provided on the substrate 83 (S105), at least two different imaging regions are set in the imaging element 175 of the position measurement device 200. Furthermore, the imaging element 175 is adjusted so that the relative ratio of the signal strength of the detection signals in each of the at least two different imaging regions falls within an allowable range. As an adjustment of the imaging element 175, for example, the sensitivity of each of the multiple pixels of the imaging element 175 is set. Then, the position of the mark 82 provided on the substrate 83 is obtained based on the output from the imaging element 175 to which the different sensitivities are set.

[0088] With reference to Fig. 9(a), Fig. 9(b) and Fig. 9(c), a measurement process for measuring the position of a mark 82 provided on a substrate 83 in this embodiment will be described. Fig. 9(a) is a diagram showing an image P15 of a device pattern on a substrate formed on an imaging region of an imaging element 175 and an image P25 of a mark 82 on the substrate. In a position measurement device 200 including a control unit 1200, position information of the mark 82 (image P25) in the imaging region (observation field) of the imaging element 175 is obtained based on an output from the imaging element 175. As shown in Fig. 9(a), an image P15 of a device pattern existing in a peripheral region around the mark 82 on the substrate is formed in the imaging region of the imaging element 175 close to the image P25 of the mark 82.

[0089] 9(b) is a diagram showing an example of a detection signal SW50 generated based on an image obtained by capturing an image P15 of the device pattern and an image P25 of the mark 82 shown in FIG. 9(a) by the image sensor 175. A waveform S150 included in the detection signal SW50 corresponds to (a change in) the signal intensity of the device pattern, and a waveform S250 included in the detection signal SW50 corresponds to (a change in) the signal intensity of the mark 82.

[0090] Here, with reference to FIG. 9(b), a case will be described in which the intensity of the detected light from the device pattern on the substrate is higher than the intensity of the detected light from the mark 82 on the substrate. In this case, as shown in FIG. 9(b), the signal intensity of the device pattern (waveform S150) is higher than the signal intensity of the mark 82 (waveform S250). Therefore, when the signal intensity in the waveform S150 exceeds a level detectable by the image sensor 175, for example, when it reaches a saturation level, the light amount detection becomes abnormal, and the position of the mark 82 cannot be obtained, that is, a measurement error may occur. In response to this, it is possible to adjust the signal intensity from the device pattern or the mark 82 by controlling the output of the light amount adjustment unit (ND filter) or the light source 161 provided in the illumination system of the position measurement device 200, or by controlling the accumulation time of the image sensor 175. However, if the observation field of the image sensor 175, i.e., the overall signal intensity of the imaging area, is reduced, the signal intensity in the waveform S250 as well as the signal intensity in the waveform S150 will be reduced. This causes electrical noise to become relatively high with respect to the signal strength in the waveform S250, making it difficult to accurately determine the measurement value X250 indicating the center position of the mark 82 on the substrate from the waveform S250.

[0091] Therefore, in this embodiment, a technique is proposed that can obtain a measurement value indicating the center position of the mark 82 with high accuracy even when the intensity difference between the detection light from the mark 82 on the substrate and the detection light from the device pattern on the substrate is large. Specifically, based on the position of the mark 82, at least two different imaging regions are set for the imaging region of the imaging element 175. In this embodiment, as shown in FIG. 9(a), a first imaging region R15 is set so as to include an image P15 of the device pattern in correspondence with the device pattern (the peripheral region around the mark 82) on the substrate. In addition, in order to image the mark 82, a second imaging region R25 is set so as to include an image P25 of the mark 82. Next, the imaging element 175 is adjusted so that the relative ratio between the intensity of the detection signal of the device pattern generated based on the output from the first imaging region and the intensity of the detection signal of the mark 82 generated based on the output from the second imaging region falls within an allowable range. For example, the adjustment of the imaging element 175 is performed by setting the sensitivity of each of the multiple pixels of the imaging element 175. Since the acquisition of signal intensity and the setting of sensitivity (calculation of sensitivity correction value) are similar to those in the first embodiment, detailed description thereof will be omitted here. Then, the position of the mark 82 is obtained based on the output from the imaging element 175, to which different sensitivities are set for the first imaging region P25 and the second imaging region R25.

[0092] FIG. 9(c) is a diagram showing an example of a detection signal SW5 generated based on an image obtained by capturing an image P15 of the device pattern and an image P25 of the mark 82 by the image sensor 175 in which different sensitivities are set for the first imaging region R15 and the second imaging region R25. Referring to FIG. 9(c), a waveform S15 included in the detection signal SW5 corresponds to (changes in) the signal intensity of the device pattern on the substrate, and a waveform S25 included in the detection signal SW5 corresponds to (changes in) the signal intensity of the mark 82. In this embodiment, by setting a lower sensitivity for the pixels included in the first imaging region R15 than for the pixels included in the second imaging region R25, it is possible to reduce the signal intensity in the waveform S15 and avoid saturation of the signal intensity in the waveform S15. This makes it possible to obtain a measurement value X25 indicating the center position of the mark 82 from the waveform S25 with high accuracy.

[0093] In the position measurement device 200, the method for measuring the position of the mark 82 on the substrate is not limited to the method for acquiring position information of the mark 82 from the signal intensity of the mark 82. For example, phase information may be obtained based on the captured image output from the image sensor 175, and the position information of the mark 82 may be acquired from the phase information.

[0094] In this embodiment, even if there is a large difference in intensity of the detected light from the mark on the substrate and the surrounding area of ​​the mark, the position of the mark can be measured quickly and with high accuracy by setting different sensitivities to the multiple imaging areas corresponding to the mark and the surrounding area of ​​the mark, respectively. Therefore, it is possible to provide a position measurement device that can measure the position of the mark on the substrate quickly and with high accuracy.

[0095] <Third embodiment> A position measurement device in the third embodiment will be described with reference to Fig. 10(a), Fig. 10(b), and Fig. 10(c). The position measurement device has a similar configuration to the position measurement device 200 shown in Fig. 7(b), so a detailed description will be omitted here. The position measurement device in this embodiment differs from the position measurement device 200 in that it does not measure the position of a mark provided on one layer on a substrate (on an object), but measures the position of a mark composed of multiple patterns provided on different layers on the substrate.

[0096] 10(a) is a diagram showing an example of the configuration of a mark 92 provided on a substrate 93 that is an object of measurement by a position measurement device. In this embodiment, the substrate 93 is a substrate that is configured with three layers: a bottom layer 93B, a first layer 93L, and a second layer 93U. The mark 92 is configured with a first pattern P16 provided on the first layer 93L, and a second pattern P26 provided on the second layer 93U. The first pattern P16 includes four pattern elements P16a, P16b, P16c, and P16d, and the second pattern P26 includes four pattern elements P26a, P26b, P26c, and P26d.

[0097] The position measurement device in this embodiment detects, by the image sensor 175, light (reflected light and scattered light) from the mark 92, specifically, from each of the first pattern P16 and the second pattern P26.

[0098] FIG. 10(b) is a diagram showing an image of the mark 92 formed on the imaging area of ​​the imaging element 175, specifically, an image of the first pattern P16 and an image of the second pattern P26. FIG. 10(c) is a diagram showing an example of a detection signal SW6 generated based on a captured image obtained by capturing the image of the mark 92 shown in FIG. 10(b) with the imaging element 175. The detection signal SW6 is generated by integrating the signal intensity of each pixel of the imaging element 175 in the Y direction for the captured image including the image of the mark 92 shown in FIG. 10(b). Referring to FIG. 10(c), a waveform S16 included in the detection signal SW6 corresponds to (changes in) the signal intensity of the first pattern P16, and a waveform S26 included in the detection signal SW6 corresponds to (changes in) the signal intensity of the second pattern P26. The control unit 1200 obtains a measurement value X16 indicating the center position of the first pattern P16 from the waveform S16, and obtains a measurement value X26 indicating the center position of the second pattern P26 from the waveform S26. Then, the control unit 1200 obtains the position information of the mark 92 based on the measurement value X16 and the measurement value X26.

[0099] In this embodiment, at least two different imaging regions are set for the imaging region of the imaging element 175 based on the position of the mark 92. Specifically, as shown in FIG. 10(b), a first imaging region R16 for imaging the first pattern P16 and a second imaging region R26 for imaging the second pattern P26 are set. Also, the imaging element 175 is adjusted so that the relative ratio between the intensity of the detection signal of the first pattern P16 generated based on the output from the first imaging region R16 and the intensity of the detection signal of the second pattern P26 generated based on the output from the second imaging region R26 falls within an allowable range. As an adjustment of the imaging element 175, for example, the sensitivity of each of the multiple pixels of the imaging element 175 is set. Note that the acquisition of the signal intensity and the setting of the sensitivity (calculation of the sensitivity correction value) are the same as in the first embodiment, and therefore a detailed description thereof will be omitted here. Then, the position of the mark 92 is obtained based on the output from the imaging element 175 to which different sensitivities are set for the first imaging region P16 and the second imaging region R26.

[0100] As a method for obtaining the position of the mark 92, there is a method for obtaining the position X36 of the mark 92 from the average value of the measurement value X16 indicating the center position of the first pattern P16 and the measurement value X26 indicating the center position of the second pattern P26. As another method, the position X36 of the mark 92 may be obtained by weighting each of the measurement value X16 indicating the center position of the first pattern P16 and the measurement value X26 indicating the center position of the second pattern P26. For example, it is preferable to weight each of the measurement values ​​X16 and X26 shown in FIG. 10(c) based on the sensitivity set for each of the first imaging region R16 and the second imaging region R26 shown in FIG. 10(b) and the evaluation parameters of the waveforms S16 and S26. Specifically, the evaluation parameters include the maximum value, minimum value, average value, and variation including noise of the signal intensity, the half-width and position information in the signal intensity distribution, and calculated values ​​based on them. In addition to the evaluation parameters of the waveform, weighting may be performed taking into consideration parameters such as the spatial position of the layer on which the pattern is exposed, the required alignment accuracy, and the throughput, for the layers on which the first pattern P16 and the second pattern P26 are provided, etc. This makes it possible to measure the position of the mark 92 on the substrate with high accuracy and to align the reticle (exposure light) and the substrate 93 with high accuracy.

[0101] In this way, the position measurement device of this embodiment can measure not only the position of a mark provided on one layer, but also the position of a mark composed of multiple patterns provided on different layers, quickly and with high accuracy.

[0102] <Fourth embodiment> The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing an article such as a device (semiconductor element, magnetic storage medium, liquid crystal display element, etc.). This manufacturing method includes a step of exposing a substrate coated with a photosensitive agent (forming a pattern on the substrate) using an exposure apparatus EXA, and a step of developing the exposed substrate (processing the substrate). This manufacturing method may also include other well-known steps (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to this embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to the conventional method. The above-mentioned method for manufacturing an article may be performed using a lithography apparatus such as an imprint apparatus or a drawing apparatus.

[0103] 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]

[0104] 100: Measurement device 50: Measurement section 72: Measurement pattern 73: Substrate 75: Imaging element 1100: Control section

Claims

1. A measurement apparatus that measures positions of a first pattern and a second pattern provided on an object, comprising: an imaging unit having an imaging element in which a plurality of pixels are arranged in two directions, the imaging unit capturing an image of the first pattern in a first imaging region of the imaging element and capturing an image of the second pattern in a second imaging region of the imaging element that is different from the first imaging region; a control unit that makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other so that a relative ratio between an intensity of a detection signal of the first pattern imaged in the first imaging area and an intensity of a detection signal of the second pattern imaged in the second imaging area falls within an acceptable range, causes the imaging unit to capture an image including the first pattern and the second pattern while images of the first pattern and the second pattern are formed on the imaging element, and determines the positions of the first pattern and the second pattern based on the images.

2. The measurement device according to claim 1, characterized in that the control unit makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other by setting the sensitivity of each of a plurality of pixels included in the first imaging area and the second imaging area.

3. The measurement device according to claim 1 or 2, characterized in that the control unit makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other by individually setting the sensitivity of the pixels included in the first imaging area and the sensitivity of the pixels included in the second imaging area.

4. The measurement device described in any one of claims 1 to 3, characterized in that the control unit makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other so that the intensity of the detection signal of the first pattern and the intensity of the detection signal of the second pattern are less than a saturation level of the imaging unit.

5. The measurement device described in any one of claims 1 to 4, characterized in that the control unit makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other by adjusting the digital gain of each of a plurality of pixels included in the first imaging area and the second imaging area.

6. The measuring apparatus according to claim 1 , wherein the control unit sets a sensitivity of the first imaging region or a sensitivity of the second imaging region to 1.

7. The control unit is sequentially performing a first measurement process for measuring the positions of the first pattern and the second pattern, and a second measurement process for measuring the positions of the first pattern and the second pattern; The measuring device according to any one of claims 1 to 6, characterized in that the first imaging area and the second imaging area are set based on the respective positions of the first pattern and the second pattern obtained in the first measurement process, and the positions of the first pattern and the second pattern are determined based on the images obtained in the second measurement process, the images being captured in a state in which the sensitivity of the first imaging area and the sensitivity of the second imaging area are set to be different from each other so that the relative ratio falls within an acceptable range.

8. 8. The measuring apparatus according to claim 7, wherein the first measurement process measures the positions of the first pattern and the second pattern with a first resolution and a first measurement range, and the second measurement process measures the positions of the first pattern and the second pattern with a second resolution higher than the first resolution and a second measurement range narrower than the first measurement range.

9. the first pattern and the second pattern are provided in different layers on the object; 9. The measurement apparatus according to claim 1, wherein the control unit determines a relative position between the first pattern and the second pattern from positions of the first pattern and the second pattern.

10. the first pattern and the second pattern are provided in different layers on the object; 9. The measurement apparatus according to claim 1, wherein the control unit determines a position of a pattern constituted by the first pattern and the second pattern from the positions of the first pattern and the second pattern.

11. A measuring device that measures a position of a mark provided on an object, comprising: an imaging unit having an imaging element in which a plurality of pixels are arranged in two directions, the imaging unit capturing an image of the mark in a first imaging region of the imaging element and capturing an image of a pattern in a peripheral region of the mark in a second imaging region of the imaging element that is different from the first imaging region; a control unit that makes the sensitivity of the first imaging area and the sensitivity of the second imaging area different from each other so that a relative ratio between an intensity of a detection signal of the mark imaged in the first imaging area and an intensity of a detection signal of the pattern imaged in the second imaging area falls within an allowable range, causes the imaging unit to capture an image including the mark and the pattern while images of the mark and the pattern are formed on the imaging element, and determines a position of the mark based on the image.

12. The measurement apparatus according to claim 11 , wherein the pattern includes a device pattern.

13. 1. A lithographic apparatus comprising: The measurement device according to claim 11 or 12, which measures the position of a mark provided on a substrate; a stage that positions the substrate based on the position of the mark measured by the measurement device; 1. A lithography apparatus comprising:

14. The lithographic apparatus of claim 13, further comprising a projection optical system for projecting a pattern of a reticle onto the substrate.

15. forming a pattern on a substrate using a lithographic apparatus according to claim 13 or 14; processing the substrate on which the pattern has been formed in the process; producing an article from the processed substrate; A method for producing an article, comprising the steps of:

16. A measurement method for measuring positions of a first pattern and a second pattern provided on an object based on an image captured by an imaging unit having an imaging element in which a plurality of pixels are arranged in two directions, comprising: the imaging unit images the first pattern in a first imaging region of the imaging element, and images the second pattern in a second imaging region of the imaging element that is different from the first imaging region; making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that a relative ratio between an intensity of a detection signal of the first pattern imaged in the first imaging region and an intensity of a detection signal of the second pattern imaged in the second imaging region falls within an allowable range, and causing the imaging unit to capture an image including the first pattern and the second pattern in a state in which images of the first pattern and the second pattern are formed on the imaging element; determining positions of the first pattern and the second pattern based on the image.

17. A measurement method for measuring a position of a mark provided on an object based on an image captured by an imaging unit having an imaging element in which a plurality of pixels are arranged in two directions, comprising: the imaging unit images the mark in a first imaging area of ​​the imaging element, and images a pattern in a peripheral area of ​​the mark in a second imaging area of ​​the imaging element that is different from the first imaging area; making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that a relative ratio between an intensity of a detection signal of the mark imaged in the first imaging region and an intensity of a detection signal of the pattern imaged in the second imaging region falls within an allowable range, and causing the imaging section to capture an image including the mark and the pattern in a state in which images of the mark and the pattern are formed on the imaging element; and determining the position of the mark based on the image.

18. The measurement method according to claim 17 , wherein the pattern includes a device pattern.

19. 1. A method for manufacturing an article, comprising: a step of capturing an image of a mark provided on a substrate by an imaging unit having an imaging element in which a plurality of pixels are arranged in two directions, and measuring the position of the mark; aligning the substrate based on a measurement result in the measuring step; forming a pattern on the substrate aligned in the aligning step; processing the substrate on which the pattern has been formed in the pattern forming step; manufacturing an article from the substrate processed in the step of processing the substrate; having the imaging unit images the mark in a first imaging area of ​​the imaging element, and images a pattern in a peripheral area of ​​the mark in a second imaging area of ​​the imaging element that is different from the first imaging area; The measuring step includes: making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that a relative ratio between an intensity of a detection signal of the mark imaged in the first imaging region and an intensity of a detection signal of the pattern imaged in the second imaging region falls within an allowable range, and causing the imaging section to capture an image including the mark and the pattern in a state in which images of the mark and the pattern are formed on the imaging element; and determining the position of the mark based on the image.

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