Measuring device, lithography device, and method for manufacturing articles

Abstract

The present invention provides a measuring device that is advantageous for measuring the position of a pattern provided on an object. [Solution] A measuring device for measuring the positions of a first pattern and a second pattern provided on an object, comprising: an imaging unit having an image sensor in which a plurality of pixels are arranged in two directions, which images the first pattern in a first imaging region of the image sensor and images the second pattern in a second imaging region of the image sensor that is different from the first imaging region; and a control unit which makes the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that the relative ratio of the intensity of the detection signal of the first pattern imaged in the first imaging region and the intensity of the detection signal of the second pattern imaged in the second imaging region falls within an acceptable range, which causes the imaging unit to image an image containing the first pattern and the second pattern with images of the first pattern and the second pattern formed on the image sensor, and which determines the positions of the first pattern and the second pattern based on the image.

Description

Technical Field

[0001] The present invention relates to a measuring device, a lithography apparatus, and a method for manufacturing an article.

Background Art

[0002] In recent years, with the progress of high integration and miniaturization of semiconductor integrated circuits, the line width of patterns to be formed on a substrate has become extremely small. Therefore, further miniaturization is required for the lithography process of forming patterns (resist patterns) on the substrate. Exposure apparatuses using the step-and-repeat method or the step-and-scan method used in the lithography process form a pattern on the substrate by imaging light (exposure light) from a reticle onto a predetermined position on the substrate through a projection optical system. Therefore, in order to meet the requirement of pattern miniaturization, it is important to align the relative positions of the reticle and the substrate with high precision (alignment). Further, with the miniaturization of patterns, it is also important to measure patterns formed on different layers (layers) on the substrate with high precision in the measurement of the overlay error of the patterns formed on the substrate.

[0003] In an exposure apparatus, generally, prior to exposure, the position of an alignment mark provided corresponding to a shot region on a substrate is measured, and global alignment is performed to obtain the arrangement (lattice arrangement) of the shot regions from such measurement results and perform alignment. In global alignment, in order to achieve both improvement in alignment accuracy and shortening of measurement time, a technique has been proposed in which a readout region is set with respect to the field of view of an imaging device to measure the position of an alignment mark (see Patent Document 1).

[0004] Patent Document 1 discloses a technique for measuring the position of an alignment mark composed of a plurality of mark elements by changing the resolution and the setting of the readout region in an imaging device. In such a technique, by sequentially performing low-resolution and wide-range mark detection and high-resolution and narrow-range mark detection, it is possible to measure the alignment mark on the substrate at high speed and with high precision.

[0005] Furthermore, in superposition measurement, which measures the superposition error of different layers formed on a substrate, the relative positions of the upper and lower layers are measured by simultaneously observing the pattern formed on the lower layer and the pattern formed on the upper layer. In superposition measurement, in order to achieve both improved measurement accuracy and reduced measurement time, a technique has been proposed in which a processing area is set for the output image from the image sensor to acquire 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 image sensor. This technique enables high-speed and high-precision measurement of the relative positions of multiple patterns formed on different layers of a substrate by generating signals corresponding to the patterns 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 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, conventional technology has a problem in that differences in reflectivity on the substrate can cause differences in the intensity of detected light between patterns on the same or different layers, leading to a decrease in measurement accuracy and a reduction in productivity due to measurement errors.

[0009] This invention has been made in view of the problems of the prior art, and its exemplary objective is to provide a measuring device that is advantageous for measuring the position of a pattern provided on an object. [Means for solving the problem]

[0010] To achieve the above objective, a measuring device as one aspect of the present invention is a measuring device for measuring the positions of a first pattern and a second pattern provided on an object, and is characterized by having an image sensor in which a plurality of pixels are arranged in two directions, an imaging unit that images the first pattern in a first imaging region of the image sensor and images the second pattern in a second imaging region of the image sensor which is different from the first imaging region, and a control unit that makes the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that the relative ratio of the intensity of the detection signal of the first pattern imaged in the first imaging region and the intensity of the detection signal of the second pattern imaged in the second imaging region falls within an acceptable range, causes the imaging unit to image an image containing the first pattern and the second pattern when images of the first pattern and the second pattern are formed on the image sensor, and determines the positions of the first pattern and the second pattern based on the image.

[0011] Further objects or other aspects of the present invention will be revealed by embodiments described below with reference to the accompanying drawings. [Effects of the Invention]

[0012] According to the present invention, for example, it is possible to provide a measuring device that is advantageous for measuring the position of a pattern provided on an object. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram illustrating the measuring device in the first embodiment of the present invention. [Figure 2] This diagram illustrates the measurement process for measuring superposition errors. [Figure 3] This diagram illustrates the challenges of conventional technology. [Figure 4] This figure illustrates the measurement process for measuring the superposition error in the first embodiment. [Figure 5]It is a flowchart for explaining the sequence of measurement processing for measuring the overlay error in the first embodiment. [Figure 6] It is a diagram for explaining a specific sensitivity correction value calculation method in S154 shown in FIG. 5. [Figure 7] It is a diagram for explaining an exposure apparatus in the second embodiment of the present invention. [Figure 8] It is a flowchart for explaining the sequence of exposure processing for exposing a substrate. [Figure 9] It is a diagram for explaining the measurement processing for measuring the position of a mark in the second embodiment. [Figure 10] It is a diagram for explaining the measurement processing for measuring the position of a mark in the third embodiment.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

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

[0016] The substrate 73 is an object for which the measurement device 100 measures the registration error. The substrate 73 is, for example, a substrate used for manufacturing devices such as semiconductor elements and liquid crystal display elements, and specifically includes wafers, liquid crystal substrates, and other substrates to be processed.

[0017] The substrate stage WS holds the substrate 73 via a substrate chuck (not shown) and is connected to a substrate drive mechanism (not shown). The substrate drive mechanism includes a linear motor or 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, Y-axis direction, Z-axis direction, and the rotational directions of each axis. Further, the position of the substrate stage WS is monitored by, for example, a six-axis laser interferometer 81, and under the control of the control unit 1100, the substrate stage WS is driven to a predetermined position.

[0018] The control unit 1100 is composed of a computer (information processing device) including a CPU, a memory, and the like, and operates the measurement device 100 by comprehensively controlling each part of the measurement device 100 according to, for example, a program stored in the storage unit. In this embodiment, the control unit 1100 controls the measurement process in the measurement device 200 and the correction process (arithmetic process) of the measurement values obtained by the measurement device 200.

[0019] Referring to FIG. 1(b), the configuration of the measurement unit 50 will be described. The measurement unit 50 includes an illumination system that illuminates the substrate 73 using light from the light source 61, and an imaging system (detection system) that forms an image of the light from the measurement pattern 72 provided on the substrate 73 on the imaging device 75 (forms an image of the measurement pattern 72). The imaging device 75 includes a plurality of pixels that detect light from the measurement pattern 72, and functions as an imaging unit that forms an imaging area for imaging the measurement pattern 72 by such a plurality of pixels. Here, the measurement pattern 72 is a pattern for measuring the registration error in the substrate 73.

[0020] Referring to Figure 1(b), light from the light source 61 is guided via illumination optics 62 and 63 to an illumination aperture diaphragm 64 positioned optically conjugate to the substrate 73. The diameter of the light beam at the illumination aperture diaphragm 64 is smaller than the diameter of the light beam at the light source 61. The light that has passed through the illumination aperture diaphragm 64 is guided via illumination optics 66, mirror M2 and relay lens 67 to a polarizing beam splitter 68. 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 that has passed through the polarizing beam splitter 68 is converted to circularly polarized light by passing through the λ / 4 plate 70 via the aperture diaphragm 69, and then illuminates the measurement pattern 72 provided on the substrate 73 via the objective optics 71.

[0021] The lighting system may also be equipped with a light intensity adjustment unit (not shown) and a wavelength adjustment unit (not shown). For example, by controlling a light intensity adjustment unit that can switch between multiple ND filters with different transmittances relative to the light from the light source 61, the intensity of the light illuminating the substrate 73 can be adjusted with high precision. Alternatively, by controlling a wavelength adjustment unit that can switch between multiple wavelength filters with different wavelength characteristics of light transmitted relative to 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 the measurement pattern 72 on the substrate 73 passes through the objective optical system 71 and the λ / 4 plate 70, where it is converted from circularly polarized light to S-polarized light and guided to the aperture diaphragm 69. Here, the polarization state of the light from the measurement pattern 72 is the opposite of the circularly polarized light illuminating the measurement pattern 72. Therefore, if the polarization state of the light illuminating the measurement pattern 72 is clockwise circularly polarized, the polarization state of the light from the measurement pattern 72 will be counterclockwise circularly polarized. The light that has passed through the aperture diaphragm 69 is reflected by the polarizing beam splitter 68 and guided to the image sensor 75 via the imaging optical system 74.

[0023] In this way, the measurement unit 50 separates the optical path of light illuminating the substrate 73 from the optical path of 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 constituting the measurement pattern 72 and the position of the measurement pattern 72 based on the 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] Furthermore, in the imaging system of the measurement unit 50, a detection aperture diaphragm may be configured by arranging multiple lenses between the polarizing beam splitter 68 and the image sensor 75. In addition, multiple aperture diaphragms may be provided in both the illumination aperture diaphragm 64 and the detection aperture diaphragm, each capable of setting different numerical apertures for the illumination system and the imaging system, respectively, and these multiple aperture diaphragms may be switchable. This makes it possible to adjust the σ value, which is a coefficient representing the ratio of the numerical aperture of the illumination system to the numerical aperture of the imaging system.

[0025] Figure 1(c) shows 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: the bottom layer 73B, the first layer 73L, and the second layer 73U. The measurement pattern 72 consists 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 measuring device 100 detects light (reflected light and scattered light) from the measurement patterns 72, specifically the first pattern P1 and the second pattern P2, using the image sensor 75 (measuring unit 50). As a method for detecting light from the measurement patterns 72, for example, dark-field detection may be used, which involves controlling the illumination aperture 64 and the detection aperture 64 (the numerical apertures of the illumination system and imaging system, respectively) to block the zero-order diffracted light from the measurement patterns 72 and detect only the higher-order diffracted light and scattered light.

[0027] Referring to Figures 2(a) and 2(b), a general operation of the measuring device 100 will be described, specifically a measurement process for measuring the overlapping error on the substrate 73, that is, a measurement process for measuring the relative positions of the first pattern P1 and the second pattern P2 that constitute the measurement pattern 72.

[0028] Figure 2(a) shows an image of the measurement pattern 72 formed on the imaging area (imaging surface or detection surface) of the image sensor 75 shown in Figure 1(b). The image sensor 75 is a two-dimensional image sensor having an imaging area composed of multiple pixels arranged in the X and Y directions. The control unit 1100 generates a detection signal including waveforms corresponding to the first pattern P1 and the second pattern P2, respectively, based on the output (imaging image) from the image sensor 75.

[0029] Figure 2(b) shows an example of a detection signal SW generated based on an image obtained by capturing an image of the measurement pattern 72 shown in Figure 2(a) with the image sensor 75. The detection signal SW is generated by integrating the signal intensity of each pixel of the image sensor 75 in the Y direction for the image including the image of the measurement pattern 72 shown in Figure 2(a). It is preferable that the number of pixels to be integrated is set based on the dimensional information of the measurement pattern 72.

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

[0031] Furthermore, when measuring the relative positional displacement in the Y direction as an overlay error, a measurement pattern consisting of a first pattern and a second pattern, each having a longitudinal direction equal to the X direction and containing multiple pattern elements arranged along the Y direction, may be used. Then, for the captured image containing the 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 displacement in the Y direction is obtained from the difference between the measured values ​​of the first pattern and the second pattern.

[0032] In this case, if there is a large difference in reflectivity between the first layer 73L and the second layer 73U of the substrate 73, a difference will occur between the light intensity corresponding to the first pattern P1 (detection light intensity) and the light intensity corresponding to the second pattern P2, as detected by the image sensor 75. Below, we will explain the problems caused by a difference 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 the decrease in measurement accuracy and the decrease in productivity due to measurement errors.

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

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

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

[0036] In the measuring device 100, the signal intensity from the measurement pattern 72 can be adjusted by controlling the output of the light intensity adjustment unit (ND filter) or light source 61 provided in the illumination system of the measuring unit 50, or by controlling the accumulation time of the image sensor 75. However, if the signal intensity of the entire observation field of view of the image sensor 75, i.e., the imaging area, is increased, the signal intensity at waveform S131 will be higher than the signal intensity at waveform S130, but the signal intensity at waveform S231 will also increase. As a result, if the signal intensity at waveform S231 exceeds the level detectable by the image sensor 75, for example, reaches the saturation level, it becomes difficult to accurately determine the measurement value X230 indicating the center position of the second pattern P2 from waveform S231.

[0037] Furthermore, it is conceivable that the measuring device 100 could perform multiple measurements by changing the light intensity illuminating the measurement pattern 72, and acquire waveforms S131 and S230 from the first pattern P1 and the second pattern P2, respectively. This would ensure that the signal intensity of waveforms S131 and S230 is below the saturation level of the image sensor 75. Consequently, it would be possible to accurately determine the measurement value X130 indicating the center position of the first pattern P1 from waveform S131, and the measurement value X230 indicating the center position of the second pattern P2 from waveform S231. However, in this case, since it is necessary to perform multiple measurements by changing the light intensity illuminating the measurement pattern 72, this may lead to decreased productivity due to increased measurement time and decreased measurement accuracy due to the passage of time (changes over time).

[0038] Therefore, in this embodiment, we propose a technique that can accurately determine the measured values ​​indicating the center positions of the first pattern P1 and the second pattern P2, even when there is a large difference in reflectivity between the first layer 73L and the second layer 73U. Specifically, based on the position of the measured pattern 72, at least two different imaging areas are set in the imaging area of ​​the image sensor 75, for example, a first imaging area for imaging the first pattern P1 and a second imaging area for imaging the second pattern P2. Furthermore, the image sensor 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 area and the intensity of the detection signal of the second pattern P2 generated based on the output from the second imaging area falls within an acceptable range. As an adjustment of the image sensor 75, for example, the sensitivity of each of the multiple pixels of the image sensor 75 is set. Then, based on the output from the image sensor 75 with different sensitivities set, the relative position (overlap error) of the first pattern P1 and the second pattern P2 is determined as the position of the first pattern P1 and the second pattern P2.

[0039] Referring to Figures 4(a) and 4(b), a measurement process for measuring the overlapping error on the substrate 73, that is, a measurement process for measuring the relative positions of the first pattern P1 and the second pattern P2 constituting the measurement pattern 72, will be described in this embodiment. Figure 4(a) shows the image of the measurement pattern 72 formed on the imaging area of ​​the image sensor 75, specifically the image P13 of the first pattern P1 and the image P23 of the second pattern P2, when the difference in reflectivity between the first layer 73L and the second layer 73U is large. As shown in Figure 4(a), the control unit 1100 sets the first imaging area R13 to include the image P13 of the first pattern P1 and the second imaging area R23 to include the image P23 of the second pattern P2, based on the position of the measurement pattern 72. Next, the control unit 1100 determines the signal intensity of the first pattern PT1, which is generated based on the output from the first imaging area R13, and the signal intensity of the second pattern PT2, which is generated based on the output from the second imaging area R23. Then, the control unit 1100 determines sensitivity correction values ​​for each of the multiple pixels of the image sensor 75, specifically the first imaging area R13 and the second imaging area R23, so that the relative ratio of the signal intensity of the first pattern PT1 and the signal intensity of the second pattern PT2 falls within an acceptable range. Finally, the control unit 1100 sets different sensitivities for each of the first imaging area R13 and the second imaging area R23 of the image sensor 75 based on the sensitivity correction values.

[0040] Figure 4(b) shows an example of a detection signal SW3 generated based on an image obtained by capturing an image of the measurement pattern 72 shown in Figure 4(a) with an image sensor 75 having different sensitivities set for the first imaging area R13 and the second imaging area R23, respectively. Referring to Figure 4(b), the waveform S13 included in the detection signal SW3 corresponds to the signal intensity (change) of the first pattern P1, and the waveform S23 included in the detection signal SW3 corresponds to the signal intensity (change) of the second pattern P2. In this embodiment, by setting a higher sensitivity for the pixels included in the first imaging area R13 than for the pixels included in the second imaging area R23, it is possible to avoid a decrease in signal intensity in waveform S13 and saturation of signal intensity in waveform S23. As a result, the measurement value X13 indicating the center position of the first pattern P1 can be determined with high accuracy from waveform S13, and the measurement value X23 indicating the center position of the second pattern P2 can be determined with high accuracy from waveform S23.

[0041] Here, there is a difference between the rate of increase in signal intensity and noise with respect to the increase in image sensor sensitivity. Specifically, while signal intensity increases proportionally to the increase in image sensor sensitivity, noise amplification changes depending on the set value of the image sensor sensitivity. This is because it includes shot noise that is not affected by the image sensor sensitivity. Generally, noise N is expressed by the following equation (1), using readout noise Nr and dark current noise Nd, which change according to the image sensor sensitivity, and shot noise Ns, which is not affected by the image sensor sensitivity.

[0042]

number

[0043] Therefore, by setting the sensitivity of the image sensor to achieve a detectable signal intensity (level) in the image sensor while avoiding a decrease in measurement accuracy due to increased noise, the measured value X13 can be determined with higher accuracy than the measured value X130.

[0044] Referring to Figure 5, the sequence of measurement processing for measuring the superposition error in this embodiment, that is, the relative position between the first pattern P1 and the second pattern P2 that constitute the measurement pattern 72, will be described. As described above, this measurement processing is performed by the control unit 1100 comprehensively controlling each part of the measurement device 100.

[0045] When the measurement process for measuring the superposition 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 image sensor 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 can be determined, and the substrate stage WS holding the substrate 73 can be positioned so that the signal intensity and its changes are greater than or equal to a target value. Alternatively, the signal intensity of the first pattern PT1 and the second pattern PT2 constituting the measurement pattern 72 can be determined, and the substrate stage WS holding the substrate 73 can be positioned so that the signal intensity and its changes are greater than or equal to a target value.

[0046] In S151, information regarding the position of the measurement pattern 72 provided on the substrate 73 (position information) is acquired. In this embodiment, the position information of the measurement pattern 72 is acquired by coarsely measuring the position of the measurement pattern 72 provided on the substrate 73. Note that the coarse measurement in S151 is performed with a lower resolution over a wider measurement range compared to the precise measurement in S156, which will be described later. Therefore, the coarse measurement in S151 and the precise measurement in S156 are defined, for example, as follows: The coarse measurement in S151 is a measurement process (first measurement process) that measures the position of the measurement pattern 72 at a first resolution and within a first measurement range. The precise measurement in S156 is a measurement process (second measurement process) that measures the position of the measurement pattern 72 at a second resolution higher than the first resolution and within a second measurement range narrower than the first measurement range. Here, the resolution of the position information refers to the size of the pixels relative to the imaging area of ​​the image sensor 75 on the substrate and the gradation of the image acquired by the image sensor 75. In coarse measurement, the increase in transfer time in the image sensor 75 and the calculation processing time in the control unit 1100 can be suppressed, and position information of the measurement pattern 72 can be acquired.

[0047] In S151, specifically, the position of the measurement pattern 72 is obtained by determining the change in signal intensity of the measurement pattern 72 based on the captured image obtained by capturing an image of the measurement pattern 72 with the image sensor 75, i.e., the captured image obtained by coarse measurement. Alternatively, the position of the measurement pattern 72 may be obtained based on the captured image obtained by coarse measurement and the pre-registered design value of the measurement pattern 72. 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 (measurement device 100).

[0048] Furthermore, in S151, in addition to roughly measuring the position of the measurement pattern 72, the wavelength and σ value of the light illuminating the measurement pattern 72 may be adjusted to settings suitable for precise measurement in S155, that is, settings that enable high-precision measurement of the position of the measurement pattern 72. Note that the settings for the wavelength and σ value of the light illuminating the measurement pattern 72 may be determined in advance, for example, based on the measurement results of the measurement pattern 72 or information regarding the structure and physical properties of the substrate 73.

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

[0050] In the imaging area of ​​the image sensor 75, multiple different imaging areas are set based on the length of the pattern to be measured in the measurement direction and the non-measurement direction. For example, by setting the imaging area to be wider than the length of the pattern in the measurement direction, the signal strength in the pattern area containing the pattern and the non-pattern area not containing the pattern may be acquired. Alternatively, by setting the imaging area to be wider than or equal to the length of the pattern in the non-measurement direction, the signal strength in the non-measurement direction of the pattern may be acquired. This makes it possible to set the sensitivity of the imaging area of ​​the image sensor 75 to the position of the pattern with high precision. 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 orthogonal to the arrangement direction of the pattern elements constituting the pattern. For example, in a 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 orthogonal to the X direction is the non-measurement direction.

[0051] In S153, information regarding the signal intensity (signal intensity information) in each of the multiple different imaging regions set on the image sensor 75 in S152 is acquired. Specifically, signal intensity information indicating the signal intensity (change) of the first pattern PT1 is acquired based on the output from the first imaging region R13. Similarly, signal intensity information indicating the signal intensity (change) of the second pattern PT2 is acquired based on the output from the second imaging region R23. The signal intensity information may be the maximum value of the signal intensity of the first pattern PT1 and the second pattern PT2, or their average value, in the detection signal generated based on the output from the image sensor 75. As a method for acquiring signal intensity information from the image acquired by the image sensor 75, for example, one method is to average the signal intensity of each pixel in the non-measurement direction Y direction for the first pattern PT1 and determine the change in signal intensity in the measurement direction X direction. By such a method, the signal intensity information of the first pattern PT1 and the second pattern PT2 can be acquired based on the outputs from the first imaging region R13 and the second imaging region R23, respectively.

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

[0053] In S155, the sensitivity is set for each of the multiple distinct imaging regions of the image sensor 75 (first imaging region R13 and second imaging region R23) based on the sensitivity correction value calculated in S154. For example, if the default sensitivity set for the image sensor is called the first sensitivity, the second sensitivity, which is the product of the first sensitivity and the sensitivity correction value, is set for each of the multiple distinct imaging regions of the image sensor 75.

[0054] In S156, positional information of the measurement pattern 72 provided on the substrate 73 is acquired using an image sensor 75, each of which has a different sensitivity set in a plurality of imaging regions, as described in S155. In this embodiment, positional 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 over a narrow measurement range (i.e., the measurement range is limited to a predetermined range) compared to the coarse measurement in S151. Specifically, a detection signal SW3 is generated based on the captured image obtained by capturing an image of the measurement pattern 72 with an image sensor 75, each of which has a different sensitivity set in a first imaging region R13 and a second imaging region R23. Then, a waveform S13 corresponding to the signal intensity (change) of the first pattern P1 and a waveform S23 corresponding to the signal intensity (change) of the second pattern P2 are extracted from the detection signal SW3. Alternatively, detection signals may be generated for each of the first imaging region R13 and the second imaging region R23, and waveforms corresponding to the signal intensity of the first pattern P1 and waveforms corresponding to the signal intensity of the second pattern P2 may be obtained from each detection signal.

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

[0056] Referring to Figures 6(a) and 6(b), the specific method for calculating the sensitivity correction value in S154 will be explained. Figure 6(a) is a diagram showing the signal intensities of the first pattern P1 and the second pattern P2 obtained from the image sensor 75 before setting the sensitivity for each of the multiple imaging areas that are different from each other in S155. In Figure 6(a), I13 represents the signal intensity of the first pattern P1, and I23 represents the signal intensity of the second pattern P2. Here, we will explain the case where the signal intensity ratio (Brightness) to the maximum detectable light amount of the image sensor 75 is, for example, 20% and the signal intensity I23 is 80%. In this case, the relative ratio of 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. If the acceptable range for the relative ratio of signal strengths is set to be between 0.5 and 1.0, then the relative ratio between signal strength I13 and signal strength I23 is not within the acceptable range.

[0057] Therefore, in this embodiment, sensitivity correction values ​​are calculated for the first imaging area R13 and the second imaging area R23, respectively, so that the relative ratio of the signal intensity of the first pattern P1 and the signal intensity of the second pattern P2 falls within an acceptable 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 acceptable range of the relative ratio of the signal intensities. For example, the target value of the signal intensity of the first pattern P1 is calculated to be 40% from the product of the signal intensity I23 (80%) and the target value of the relative ratio of the signal intensities (e.g., 0.5). Thus, the sensitivity correction value for the first imaging area R13 is calculated to be 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, for the second imaging area R23, a sensitivity correction value is calculated so that the relative ratio of the signal intensities falls within an acceptable range. Furthermore, if the signal intensity ratio to the maximum detectable light amount of the image sensor 75 is not changed, the sensitivity correction value for the second imaging area R23 is calculated to be 1.0.

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

[0059] Figure 6(b) shows the signal intensities of the first pattern P1 and the second pattern P2 obtained from the image sensor 75 after setting the sensitivity for each of several different imaging regions in S155. In Figure 6(b), I14 shows the signal intensity of the first pattern P1, and I24 shows 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 Figure 6(b), signal intensities I14 and I24 have the same intensity. In addition, the relative ratio of signal intensities I14 and I24 has increased to 0.5 compared to the relative ratio of signal intensities I13 and I23 shown in Figure 6(a), which is 0.25. As a result, the relative ratio of signal intensities I14 and I24 falls within the acceptable range (0.5 or more and 1.0 or less), making it possible to determine the relative position of the first pattern P1 and the second pattern P2 with high accuracy.

[0060] Furthermore, it is preferable to set the sensitivity for each of the multiple, different imaging regions in the image sensor 75 by adjusting the digital gain of the image sensor 75. For example, if the sensitivity is set by adjusting the storage time of the image sensor 75, the difference in storage time may cause errors due to positional changes of the substrate stage WS to be included in the measured values ​​of the first pattern P1 and the second pattern P2. This can reduce the measurement accuracy of the relative position between the first pattern P1 and the second pattern P2.

[0061] Furthermore, it is preferable that the digital gain (sensitivity) set for at least one of the multiple, mutually distinct imaging regions in the image sensor 75 be 1. This is because, as the sensitivity value set for the image sensor 75 increases, there is a possibility that the measurement accuracy will decrease due to the increase in noise.

[0062] To set the digital gain to 1 for at least one of several distinct imaging regions on the image sensor 75, signal intensity information can 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, which has a high signal intensity ratio to the maximum detectable light amount of the image sensor 75, is brought to a level detectable by the image sensor 75 by adjusting the light intensity in the illumination system of the measurement unit 50, controlling the output of the light source 61, or controlling the storage time of the image sensor 75. Then, in S155, the sensitivity is set for each of the several distinct imaging regions on 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, which has a low signal intensity ratio to the maximum detectable 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, avoiding a decrease in measurement accuracy due to increased noise, and enabling highly accurate determination of the relative position between the first pattern P1 and the second pattern P2.

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

[0064] According to this embodiment, even when there are differences in the intensity of detected light between patterns in different layers on a substrate, the relative position between patterns can be measured quickly and with high accuracy by setting different sensitivities for multiple imaging regions corresponding to each pattern. Furthermore, by setting different values ​​for the pixel sensitivity rather than the storage time in the image sensor, a decrease in productivity due to multiple measurements can be avoided. Moreover, by setting different sensitivities for the pixels of the image sensor rather than the captured image output from the image sensor, a decrease in measurement accuracy can be avoided even when the intensity of detected light from multiple patterns differs, and the relative positions of multiple patterns can be measured with high accuracy. Therefore, a measuring device capable of quickly and accurately measuring the relative positions of multiple patterns on a substrate can be provided.

[0065] <Second Embodiment> Figure 7(a) is a schematic diagram showing the configuration of the exposure apparatus EXA. The exposure apparatus EXA is a lithography apparatus used in the lithography process, which is a manufacturing process for devices such as semiconductor elements and liquid crystal display elements, to form patterns on a substrate 83. The exposure apparatus EXA exposes the substrate 83 through a reticle 31, which is the master plate, and transfers the pattern of the reticle 31 to 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 Figure 7(a), the exposure apparatus EXA includes an illumination optical system 801, a reticle stage RS that holds the reticle 31, a projection optical system 32, a substrate stage WS that holds the substrate 83, a position measuring device 200, and a control unit 1200.

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

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

[0069] The reticle 31 is made of, for example, quartz. The reticle 31 has a pattern (circuit pattern) formed on it that should be transferred to the substrate 83.

[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 drives the reticle stage RS in the X-axis, Y-axis, Z-axis, and rotational directions of 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 measuring unit (not shown) of the oblique incidence system, and the reticle 31 is positioned at a predetermined position via the reticle stage RS.

[0071] The projection optical system 32 has the function of forming an image of light from the object surface onto the image plane. 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, forming an image of the pattern of the reticle 31 on the substrate. The projection optical system 32 can be an optical system consisting of a plurality of lens elements, an optical system including a plurality of lens elements and at least one concave mirror (catedioptric optical system), or an optical system including a plurality of lens elements and at least one diffractive optical element such as a kinoform.

[0072] A photoresist is coated onto the substrate 83. The substrate 83 is the workpiece onto which the pattern of the reticle 31 is transferred, and includes wafers, liquid crystal substrates, and other workpieces.

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

[0074] The positions of the reticle stage RS and the substrate stage WS are monitored, for example, by a 6-axis laser interferometer 91, and the reticle stage RS and the substrate stage WS are driven at a constant speed ratio under the control of the control unit 1200.

[0075] The control unit 1200 is composed of a computer (information processing device) including a CPU and memory, and for example, it comprehensively controls each part of the exposure device EXA according to a program stored in the memory unit to operate the exposure device EXA. The control unit 1200 controls the 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 measuring device 200 and the correction process (calculation process) of the measured values ​​obtained by the position measuring device 200. In this way, the control unit 1200 also functions as part of the position measuring device 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 arranged in an optically conjugate relationship. By scanning the reticle 31 and the substrate 83 at a speed ratio equal to the reduction ratio of the projection optical system 32, the pattern of the reticle 31 is transferred to the substrate 83.

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

[0078] The position measuring device 200 includes an illumination system that illuminates the substrate 83 using 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 consists of illumination optical systems 162, 163 and 166, an illumination aperture diaphragm 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 consists of an objective optical system 171, a λ / 4 plate 170, a detection aperture diaphragm 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 the image sensor 175. The image sensor 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 with these plurality of pixels. The control unit 1200 acquires the position of the mark 82 on the substrate based on the position information of the substrate stage WS obtained by the laser interferometer 91 and the waveform of the detection signal obtained by detecting the image of the mark 82.

[0079] Referring to Figure 8, the sequence of the 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 will be described. As described above, this exposure process is carried out by the control unit 1200 comprehensively controlling each part of the exposure apparatus EXA.

[0080] In S101, the substrate 83 is loaded into the exposure apparatus EXA. In S102, the surface (height) of the substrate 83 is detected by a shape measuring device (not shown) and the surface shape of the entire substrate 83 is measured.

[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 measuring 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 relative to the optical axis of the position measuring device 200 is measured, and based on this positional deviation, the stage coordinate system is reset so that the origin of the stage coordinate system coincides with the optical axis of the position measuring device 200. Then, 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 measuring device 200 and the optical axis of the projection optical system 32. Finally, the positional deviation of the reference mark relative to the optical axis of the exposure light is measured via the projection optical system 32 using a TTL (through-the-lens) measurement system.

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

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

[0084] In S106, global alignment is performed. Specifically, based on the measurement results in S105, the shift, magnitude, and rotation of the shot area arrangement on the substrate 83 are calculated to determine the regularity of the shot area arrangement. Then, a correction coefficient is determined from the regularity of the shot area arrangement and the baseline, and the substrate 83 is aligned with the reticle 31 (exposure light) based on this 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 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 has been completed for all shot areas of the substrate 83 (i.e., whether there are any unexposed shot areas). If exposure has not been completed for all shot areas of the substrate 83, the process proceeds to S107, and steps S107 and S108 are repeated until exposure has been completed for all shot areas. On the other hand, if exposure has been completed for all shot areas of the substrate 83, the process proceeds to S109, and the substrate 83 is removed from the 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 areas are set in the image sensor 175 of the position measuring device 200. Furthermore, the image sensor 175 is adjusted so that the relative ratio of the signal intensity of the detection signal in each of the at least two different imaging areas falls within an acceptable range. As an adjustment of the image sensor 175, for example, the sensitivity of each of the multiple pixels of the image sensor 175 is set. Then, the position of the mark 82 provided on the substrate 83 is determined based on the output from the image sensor 175 with different sensitivities set.

[0088] Referring to Figures 9(a), 9(b), and 9(c), the measurement process for measuring the position of the mark 82 provided on the substrate 83 in this embodiment will be described. Figure 9(a) is a diagram showing the image P15 of the device pattern on the substrate and the image P25 of the mark 82 on the substrate, formed on the imaging area of ​​the image sensor 175. In the position measuring device 200, which includes the control unit 1200, position information of the mark 82 (image P25) in the imaging area (observation field) of the image sensor 175 is acquired based on the output from the image sensor 175. As shown in Figure 9(a), in the imaging area of ​​the image sensor 175, the image P15 of the device pattern present in the peripheral area around the mark 82 on the substrate is formed in close proximity to the image P25 of the mark 82.

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

[0090] Here, referring to Figure 9(b), we will explain the case where 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 Figure 9(b), the signal intensity of the device pattern (waveform S150) is higher than the signal intensity of the mark 82 (waveform S250). Therefore, if the signal intensity of waveform S150 exceeds the level detectable by the image sensor 175, for example, if it reaches the saturation level, the light intensity detection becomes abnormal, and the position of the mark 82 cannot be determined, which may result in a measurement error. To address this, it is possible to adjust the signal intensity from the device pattern and the mark 82 by controlling the light intensity adjustment unit (ND filter) or the output of 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 signal intensity of the entire observation field of view of the image sensor 175, i.e., the imaging area, is lowered, the signal intensity of waveform S250 will also decrease along with the signal intensity of waveform S150. As a result, the electrical noise relative to the signal strength in waveform S250 becomes relatively high, making it difficult to accurately determine the measurement value X250, which indicates the center position of mark 82 on the circuit board, from waveform S250.

[0091] Therefore, in this embodiment, we propose a technique that can accurately determine a measurement value indicating the center position of mark 82 even when there is a large difference in intensity between the detected light from mark 82 on the substrate and the detected light from the device pattern on the substrate. Specifically, based on the position of mark 82, at least two different imaging regions are set for the imaging region of the image sensor 175. In this embodiment, as shown in Figure 9(a), the first imaging region R15 is set to include the image P15 of the device pattern (the peripheral region around mark 82) corresponding to the device pattern on the substrate. In addition, the second imaging region R25 is set to include the image P25 of mark 82 in order to image mark 82. Next, the image sensor 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 mark 82 generated based on the output from the second imaging region falls within an acceptable range. As an adjustment of the image sensor 175, for example, the sensitivity of each of the multiple pixels of the image sensor 175 is set. Note that the acquisition of signal strength and setting of sensitivity (calculation of sensitivity correction value) are the same as in the first embodiment, so a detailed explanation is omitted here. Then, the position of mark 82 is determined based on the output from the image sensor 175, which has different sensitivities set for the first imaging area P25 and the second imaging area R25.

[0092] Figure 9(c) shows an example of a detection signal SW5 generated based on an image obtained by capturing an image of a device pattern P15 and an image of mark 82 P25 with an image sensor 175 having different sensitivities set for the first imaging area R15 and the second imaging area R25, respectively. Referring to Figure 9(c), the waveform S15 included in the detection signal SW5 corresponds to the signal intensity (change) of the device pattern on the substrate, and the waveform S25 included in the detection signal SW5 corresponds to the signal intensity (change) of mark 82. In this embodiment, by setting a lower sensitivity for the pixels included in the first imaging area R15 than for the pixels included in the second imaging area R25, it is possible to reduce the signal intensity in waveform S15 and avoid signal intensity saturation in waveform S15. As a result, the measured value X25 indicating the center position of mark 82 can be determined with high accuracy from waveform S25.

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

[0094] In this embodiment, even when there is a large difference in the intensity of 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 for multiple imaging areas corresponding to the mark and the surrounding area of ​​the mark, respectively. Therefore, a position measuring device capable of measuring the position of a mark on a substrate quickly and with high accuracy can be provided.

[0095] <Third Embodiment> The position measuring device in the third embodiment will be described with reference to Figures 10(a), 10(b), and 10(c). The position measuring device has a similar configuration to the position measuring device 200 shown in Figure 7(b), so a detailed explanation will be omitted here. The position measuring device in this embodiment differs from the position measuring device 200 in that it measures the position of marks composed of multiple patterns provided on different layers of the substrate, rather than measuring the position of a mark provided on a single layer on the substrate (on the object).

[0096] Figure 10(a) shows an example of the configuration of a mark 92 provided on a substrate 93, which is the object to be measured by the position measuring device. In this embodiment, the substrate 93 is a substrate composed of three layers: the bottom layer 93B, the first layer 93L, and the second layer 93U. The mark 92 is composed of 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] In this embodiment, the position measuring device detects light (reflected light and scattered light) from the mark 92, specifically from the first pattern P16 and the second pattern P26, using the image sensor 175.

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

[0099] In this embodiment, at least two different imaging regions are set for the imaging area of ​​the image sensor 175 based on the position of mark 92. Specifically, as shown in Figure 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. The image sensor 175 is also adjusted so that the relative ratio between the intensity of the detection signal for the first pattern P16, generated based on the output from the first imaging region R16, and the intensity of the detection signal for the second pattern P26, generated based on the output from the second imaging region R26, falls within an acceptable range. As an adjustment of the image sensor 175, for example, the sensitivity of each of the multiple pixels of the image sensor 175 is set. Note that the acquisition of signal intensity and the setting of sensitivity (calculation of sensitivity correction value) are the same as in the first embodiment, so a detailed explanation is omitted here. The position of mark 92 is then determined based on the output from the image sensor 175, which has different sensitivities set for the first imaging region P16 and the second imaging region R26.

[0100] One method for determining the position of Mark 92 is to calculate the position X36 of Mark 92 from the average value of the measured value X16 indicating the center position of the first pattern P16 and the measured value X26 indicating the center position of the second pattern P26. Alternatively, the position X36 of Mark 92 may be determined by weighting the measured value X16 indicating the center position of the first pattern P16 and the measured value X26 indicating the center position of the second pattern P26. For example, the measured values ​​X16 and X26 shown in Figure 10(c) may be weighted based on the sensitivity and evaluation parameters of the waveforms S16 and S26 set for the first imaging area R16 and the second imaging area R26, respectively, as shown in Figure 10(b). Specifically, evaluation parameters include the maximum, minimum, and average values ​​of signal intensity, variability including noise, half-width and position information in the signal intensity distribution, and calculated values ​​based on these. Furthermore, in addition to the waveform evaluation parameters, the layers on which the first pattern P16 and the second pattern P26 are provided may be weighted by considering parameters such as the spatial position of the layer on which the pattern is exposed, the required alignment accuracy, and throughput. This makes it possible to measure the position of the mark 92 on the substrate with high precision and to align the reticle (exposure light) and the substrate 93 with high precision.

[0101] Thus, the position measuring device of this embodiment can measure the position of marks composed of multiple patterns located on different layers, not just marks on a single layer, with high speed and high accuracy.

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

[0103] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0104] 100: Measuring device 50: Measuring unit 72: Measurement pattern 73: Substrate 75: Image sensor 1100: Control unit

Claims

1. A measuring device for measuring the positions of a first pattern and a second pattern provided on an object, An imaging unit having an image sensor in which multiple pixels are arranged in two directions, capturing the first pattern in a first imaging region of the image sensor, and capturing the second pattern in a second imaging region of the image sensor that is different from the first imaging region, A measuring device comprising: a control unit that determines the positions of the first and second patterns based on the image, wherein the sensitivity of the first imaging area and the sensitivity of the second imaging area are made different from each other so that the relative ratio of the intensity of the detection signal of the first pattern captured in the first imaging area and the intensity of the detection signal of the second pattern captured in the second imaging area falls within an acceptable range; the imaging unit captures an image containing the first and second patterns while images of the first and second patterns are formed on the image sensor; and the imaging unit captures an image containing the first and second patterns based on the image.

2. The measuring device according to claim 1, characterized in that the control unit sets the sensitivity of each of the plurality of pixels included in the first imaging region and the second imaging region so that the sensitivity of the first imaging region and the sensitivity of the second imaging region are different from each other.

3. The measuring device according to claim 1 or 2, characterized in that the control unit sets the sensitivity of the pixels included in the first imaging region and the sensitivity of the pixels included in the second imaging region individually, thereby making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other.

4. The measuring device according to 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 the saturation level of the imaging unit.

5. The measuring device according to any one of claims 1 to 4, characterized in that the control unit adjusts the digital gain of each of the plurality of pixels included in the first imaging region and the second imaging region to make the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other.

6. The measuring device according to any one of claims 1 to 5, characterized in that the control unit sets the sensitivity of the first imaging region or the sensitivity of the second imaging region to 1.

7. The control unit, 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 are performed in order. A measuring device according to any one of claims 1 to 6, characterized in that the first imaging region and the second imaging region 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 image obtained in the second measurement process, which is captured with the sensitivity of the first imaging region and the sensitivity of the second imaging region set to be different from each other so that the relative ratio falls within an acceptable range.

8. The measuring device according to claim 7, characterized in that 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 on different layers of the object. The measuring device according to any one of claims 1 to 8, characterized in that the control unit determines the relative position between the first pattern and the second pattern from the positions of the first pattern and the second pattern.

10. The first pattern and the second pattern are provided on different layers of the object. The measuring device according to any one of claims 1 to 8, characterized in that the control unit determines the position of the pattern composed of the first pattern and the second pattern from the positions of the first pattern and the second pattern.

11. A measuring device for measuring the position of a mark placed on an object, An imaging unit having an image sensor in which multiple pixels are arranged in two directions, capturing the mark in a first imaging region of the image sensor, and capturing a pattern in a peripheral region of the mark in a second imaging region of the image sensor that is different from the first imaging region, A measuring device comprising: a control unit that causes the imaging unit to capture an image of the mark and the pattern with images of the mark and the pattern formed on the image sensor, and determines the position of the mark based on the image; the relative ratio of the intensity of the detection signal of the mark captured in the first imaging unit to the intensity of the detection signal of the pattern captured in the second imaging unit to fall within an acceptable range; the relative sensitivity of the first imaging unit and the sensitivity of the second imaging unit to be different from each other first imaging unit and the sensitivity of the second imaging unit to be different from each other; the relative sensitivity of the first imaging unit and the sensitivity of the first imaging unit and the sensitivity of the

12. The measuring device according to claim 11, characterized in that the pattern includes a device pattern.

13. A lithography device, A measuring device according to any one of claims 11 or 12 for measuring the position of a mark provided on a substrate, A stage for positioning the substrate based on the position of the mark measured by the measuring device, A lithography apparatus characterized by having [a certain feature].

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

15. A step of forming a pattern on a substrate using the lithography apparatus described in claim 13 or 14, A step of processing the substrate on which the pattern has been formed in the above step, A process for manufacturing an article from the processed substrate, A method for manufacturing an article, characterized by having the following:

16. A measurement method for measuring the positions of a first pattern and a second pattern provided on an object, based on an image captured by an imaging unit having an image sensor in which multiple pixels are arranged in two directions, The imaging unit captures the first pattern in a first imaging region of the image sensor, and captures the second pattern in a second imaging region of the image sensor that is different from the first imaging region. The steps include: making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that the relative ratio of the intensity of the detection signal of the first pattern captured in the first imaging region and the intensity of the detection signal of the second pattern captured in the second imaging region falls within an acceptable range, and causing the imaging unit to capture an image containing the first pattern and the second pattern while images of the first pattern and the second pattern are formed on the image sensor; A measurement method characterized by comprising the step of determining the positions of the first pattern and the second pattern based on the aforementioned image.

17. A measurement method for measuring the position of a mark provided on an object based on an image captured by an imaging unit having an image sensor in which multiple pixels are arranged in two directions, The imaging unit captures the mark in a first imaging region of the image sensor, and captures a pattern in a peripheral region of the mark in a second imaging region of the image sensor, which is different from the first imaging region. The process involves making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that the relative ratio of the intensity of the detection signal of the mark captured in the first imaging region and the intensity of the detection signal of the pattern captured in the second imaging region falls within an acceptable range, and causing 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 image sensor. A measurement method characterized by comprising the step of determining the position of the mark based on the aforementioned image.

18. The measurement method according to claim 17, characterized in that the pattern includes a device pattern.

19. A method for manufacturing an article, A process of capturing an image of a mark provided on a substrate using an imaging unit having an image sensor with multiple pixels arranged in two directions, and measuring the position of the mark, Based on the measurement results in the measurement process, the process of aligning the substrate, The process of forming a pattern on the substrate that has been aligned in the alignment process, The process of forming the pattern includes processing the substrate on which the pattern has been formed, The process of processing the substrate includes a step of manufacturing an article from the processed substrate, It has, The imaging unit captures the mark in a first imaging region of the image sensor, and captures a pattern in a peripheral region of the mark in a second imaging region of the image sensor, which is different from the first imaging region. The measurement process described above is: The process involves making the sensitivity of the first imaging region and the sensitivity of the second imaging region different from each other so that the relative ratio of the intensity of the detection signal of the mark captured in the first imaging region and the intensity of the detection signal of the pattern captured in the second imaging region falls within an acceptable range, and causing 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 image sensor. A method for manufacturing an article, comprising the step of determining the position of the mark based on the aforementioned image.

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