Plasma processing device, misalignment amount detection device, and misalignment amount correction method

Abstract

The present invention provides a technique that enables direct detection of a misalignment amount of a sample (wafer) with respect to a placement section (a wafer installation section) when the sample is to be processed, and that enables the sample to be positioned highly accurately with respect to the placement section. The present invention comprises: a sample table equipped with a placement section on which a sample is placed; and a misalignment amount detection device for detecting a misalignment amount of the sample with respect to the placement section. The present invention provides a technique with which the misalignment amount of the sample with respect to the placement section is detected by the misalignment amount detection device on the basis of a first image including an outer peripheral portion of the sample and a second image including an outer peripheral portion of the placement section.

Description

Plasma processing apparatus, positional deviation detection device, and positional deviation correction method

[0001] The present disclosure relates to a plasma processing apparatus, a positional deviation detection apparatus, and a positional deviation correction method.

[0002] In recent years, the market has been demanding higher power consumption and speed for semiconductor devices, and there has been a noticeable trend toward more complex and highly integrated device structures. Accordingly, the precision required for wafer placement when processing sample wafers is increasing year by year from the perspectives of yield and reproducibility.

[0003] On the other hand, the performance of imaging devices that capture images is improving year by year, and examples of using imaging devices to position transported objects have also been proposed. For example, Patent Document 1 proposes a positional deviation detection device that calculates the amount of positional deviation of a transported object relative to a transport mechanism based on an image captured by an image sensor.

[0004] Japanese Patent Application Laid-Open No. 2022-77966

[0005] Although Patent Document 1 detects the amount of misalignment of the transported object relative to the transport mechanism, it cannot directly detect the placement position of the wafer when processing the wafer. Furthermore, in order to detect the amount of misalignment with high precision, it is desirable to be able to detect the outer periphery of the wafer placement section and the outer periphery position of the wafer.

[0006] The present disclosure provides a technique for directly detecting the amount of positional deviation of a sample (wafer) relative to a mounting part (wafer mounting part) when processing the sample, and for positioning the sample relative to the mounting part with high accuracy.

[0007] A plasma processing apparatus according to one aspect of the present disclosure includes a sample stage having a mounting portion on which a sample is placed, and a positional deviation detection device that detects the amount of positional deviation of the sample relative to the mounting portion, and the positional deviation detection device detects the amount of positional deviation of the sample relative to the mounting portion based on a first image including the outer periphery of the sample and a second image including the outer periphery of the mounting portion.

[0008] In other words, to solve the above-mentioned problems, one representative wafer position detection method according to the present disclosure relates to a detection technique for a misalignment detection device that detects the amount of misalignment of a wafer relative to a wafer placement unit in a plasma processing apparatus equipped with a sample stage having a placement unit (wafer placement unit) on which a sample (wafer) is placed. The misalignment detection device is disposed above the wafer placement unit and includes an imaging device that captures a first image including the outer periphery of the wafer and a second image including the outer periphery of the wafer placement unit. The misalignment detection device detects and calculates the amount of misalignment between the wafer placement unit and the wafer based on multiple images including the first and second images captured by the imaging device. The calculation of the misalignment amount can be performed, for example, by an image processing unit.

[0009] According to the present disclosure, it is possible to provide a technique for directly detecting the amount of positional deviation of a sample relative to a mounting part when processing the sample, and for positioning the sample relative to the mounting part with high accuracy.

[0010] FIG. 1 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer placement unit according to a first embodiment. FIG. 2 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer placement unit according to a first embodiment. FIG. 3 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer placement unit according to a first embodiment. FIG. 4 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer on a transfer mechanism relative to a wafer placement unit according to a second embodiment. FIG. 5 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer on a transfer mechanism relative to a wafer placement unit according to a second embodiment. FIG. 6 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer on a wafer placement unit relative to a wafer placement unit according to a third embodiment. FIG. 7 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer on a wafer placement unit relative to a wafer placement unit according to a third embodiment. FIG. 8 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer placement unit according to a fourth embodiment using image difference processing. FIG. 9 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer placement unit according to a fifth embodiment using image center of gravity calculation processing. FIG. 10 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer mounting part according to a sixth embodiment by correcting the position of an imaging device. FIG. 11 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer mounting part according to a seventh embodiment by using multiple imaging devices. FIG. 12 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer mounting part according to an eighth embodiment by correcting the influence of a structure that is transparent to visible light. FIG. 13 is a diagram showing an example of a detection method for detecting a positional deviation of a wafer relative to a wafer mounting part according to the eighth embodiment by correcting the influence of a structure that is transparent to visible light. FIG. 14 is a diagram showing an example of a correction method for correcting a positional deviation of a wafer relative to a wafer mounting part according to a ninth embodiment. FIG. 15 is a diagram showing an example of a correction method for correcting a positional deviation of a wafer relative to a wafer mounting part according to a tenth embodiment.

[0011] Hereinafter, embodiments will be described with reference to the drawings. However, in the following description, the same components will be assigned the same reference numerals, and repeated description may be omitted. Note that the drawings may be more schematic than the actual embodiment to make the description clearer, but they are merely examples and do not limit the interpretation of the present invention.

[0012] [First Example] FIGS. 1, 2, and 3 are diagrams illustrating an example of a detection method for detecting misalignment of a wafer relative to a wafer mounting portion according to a first example of the present disclosure. An example of a plasma processing apparatus using this detection method is shown in FIG. 1A. A plasma processing apparatus 100 according to this embodiment includes a plasma processing chamber 101 and a wafer mounting portion 102. The wafer mounting portion 102 is a mounting portion on which a sample wafer is mounted, and this mounting portion 102 is provided on a sample stage. An exhaust device 109 for evacuating the plasma processing chamber 101 is connected. The sample stage having the wafer mounting portion 102 is made of aluminum or titanium, and a thermally sprayed film made of alumina ceramics or the like is disposed on its upper surface. An imaging device 103 is held by an imaging device holding member 104 and connected to the plasma processing chamber 101. An image processing unit 105 is optionally connected to the imaging device 103 via, for example, a USB cable, and transfers and processes captured images. An example of an image acquired by the imaging device 103 is shown in FIG. 2A. An image 202 obtained by observing the wafer placement section 102 from directly above is obtained.

[0013] An example of a plasma processing apparatus using this detection method is shown in FIG. 1B. In addition to the configuration of FIG. 1A, a wafer 106 is placed above a wafer placement unit 102. The wafer 106 may be held by a transfer mechanism (not shown), on pins (not shown), or on the wafer placement unit 102, or any other holding method may be used as long as it is above the wafer placement unit 102. The wafer 106 may be made of, for example, silicon (Si), black silicon (Black Si), silicon nitride (SiN), silicon dioxide (SiO ２2B shows an example of an image acquired by the imaging device 103 at this time. An image 206 is obtained by observing the wafer 106 from directly above.

[0014] From the thus obtained image (second image) 202 obtained by observing the wafer placement part 102 from directly above and the image (first image) 206 obtained by observing the wafer 106 from directly above, the positional deviation of the wafer 106 with respect to the wafer placement part 102 is detected. The image 206, which is the first image, is an image including the outer periphery of the wafer 106, which is a sample placed above the placement part 102, or an image including the entire sample wafer 106. The image 202, which is the second image, is an image including the outer periphery of the placement part 102, or an image including the entire placement part 102.

[0015] 2C, as an example, the image processing unit 105 creates a difference image 207 from the image 202 and the image 206. Because the wafer 106 has a larger diameter than the wafer placement unit 102 and is positioned higher than the wafer placement unit 102, the wafer 106 is photographed as being larger than the wafer placement unit 102. Therefore, the difference image 207 indicates how much the circular shape observed from directly above the wafer 106 exceeds the circular shape observed from directly above the wafer placement unit 102, and by observing this profile, it is possible to detect the amount of misalignment of the wafer 106 with respect to the wafer placement unit 102. Furthermore, by acquiring multiple images 202 and 206, noise can be reduced and the amount of misalignment can be detected with higher accuracy.

[0016] In other words, the image processing unit 105 is regarded as a positional deviation detection device that detects the positional deviation of the sample 106 with respect to the mounting unit 102. The image processing unit 105 detects the positional deviation of the sample 106 with respect to the mounting unit 102 based on the first image 206 and the second image 202. In detecting the positional deviation, the image processing unit 105 performs differential processing between the image 202 and the image 206 to generate a differential image 207. Then, the image processing unit 105 detects the positional deviation of the sample 106 with respect to the mounting unit 102 based on the differential image obtained by the differential processing.

[0017] 3 shows an example of an image acquired by the imaging device 103 when a positional deviation occurs in the wafer 106. FIG. 3(a) shows an image (second image) 302 obtained by observing the wafer placement part 102 from directly above, which is equivalent to image 202. FIG. 3(b) shows an image (first image) 306 obtained by observing the wafer 106, which has a positional deviation, from directly above, and FIG. 3(c) shows a difference image 307 created from images 302 and 306. In this way, the image processing part 105 creates the difference image 307, and furthermore, it becomes possible to detect the amount of positional deviation of the wafer 106 relative to the wafer placement part 102 from its profile.

[0018] Second Embodiment FIGS. 4 and 5 are diagrams illustrating an example of a detection method for detecting misalignment of a wafer relative to a wafer placement unit according to a second embodiment of the present disclosure. As shown in FIG. 4 , the wafer 106 is held and placed above the wafer placement unit 102 by the transport mechanism 407. FIG. 5B illustrates an example of an image (first image) acquired by the imaging device 103 at this time. An image (first image) 506 is obtained by observing the wafer 106 held by the transport mechanism 407 and placed above the wafer placement unit 102 from directly above. The first image 506 includes the outer periphery of the sample 106 placed above the mounting unit 102. An image (second image) 502 of the wafer placement unit 102 observed from directly above, as shown in FIG. 5A, is acquired before the wafer 106 is loaded into the plasma processing chamber 101. The misalignment of the wafer relative to the wafer placement unit is detected from the image 502 of the wafer placement unit 102 observed from directly above and the image 506 of the wafer 106 observed from directly above. 5C, the image processing unit 105 creates a difference image 507 from the image 502 and the image 506. By observing this profile, it is possible to detect the amount of misalignment of the wafer 106 with respect to the wafer placement unit 102. At this time, since the wafer 106 is held by the transfer mechanism 407, controlling the transfer mechanism 407 makes it easy to correct the amount of misalignment and re-detect the amount of misalignment at the corrected position.

[0019] Third Embodiment FIGS. 6 and 7 are diagrams illustrating an example of a detection method for detecting misalignment of a wafer relative to a wafer placement unit according to a third embodiment of the present disclosure. As shown in FIG. 6 , a wafer 106 is placed on the wafer placement unit 102. FIG. 7B shows an example of an image (first image) acquired by the imaging device 103 at this time. An image (first image) 706 is obtained by observing the wafer 106 placed on the wafer placement unit 102 from directly above. An image (second image) 702, which is an image of the wafer placement unit 102 observed from directly above, shown in FIG. 7A is acquired before the wafer 106 is loaded into the plasma processing chamber 101. The image 702, which is an image of the wafer placement unit 102 observed from directly above, and the image 706, which is an image of the wafer 106 observed from directly above, are used to detect misalignment of the wafer relative to the wafer placement unit. As an example, as shown in FIG. 7C , the image processing unit 105 creates a difference image 707 from the image 702 and the image 706. Observing this profile makes it possible to detect the amount of misalignment of the wafer 106 relative to the wafer placement part 102. At this time, the wafer 106 is placed and held on the wafer placement part 102. That is, the wafer 106 is placed at a position where plasma processing will actually be performed. Therefore, this method makes it possible to detect in detail the amount of misalignment of the wafer 106 when it is actually processed.

[0020] [Fourth Example] FIG. 8 is a diagram illustrating an example of a detection method for detecting wafer misalignment relative to a wafer placement unit according to a fourth example embodiment of the present disclosure. (a) in FIG. 8 illustrates a difference image 807 created when a wafer misalignment occurs. At this time, the image processing unit 105 focuses on, for example, a left region 807a and a right region 807b of the difference image 807 and acquires profiles. After acquiring the profiles, a profile 808a of the left region 807a and a profile 808b of the right region 807b are obtained, as shown in (b) in FIG. 8. If the width Xa of the profile of the left region 807a is 100 pixels and the width Xb of the profile of the right region 807b is 200 pixels, the wafer 106 can be said to be misaligned to the right by (200-100) / 2 = 50 pixels. If one pixel is 0.1 mm, the amount of misalignment in the X direction can be detected as 5 mm. The profile width can be acquired in subpixels by processing multiple rows or by performing appropriate interpolation. Similarly, in the Y direction, the amount of misalignment in the Y direction can also be detected by acquiring profiles of the upper and lower regions and observing the difference between the top and bottom. Furthermore, the amount of misalignment may be detected with higher accuracy by performing similar processing in directions other than up, down, left, and right. In this method, the misalignment detection device 105 performs differential processing between the first image and the second image, and the amount of misalignment of the sample relative to the mounting part 102 is detected based on the differentially processed image. In this method, when there is a disturbance factor such as uneven brightness or blur in the images (first image and second image), the disturbance factor can be offset by differential processing, making it possible to detect the amount of misalignment of the wafer 106 even in such an environment.

[0021] Fifth Embodiment FIG. 9 is a diagram illustrating an example of a detection method for detecting a misalignment of a wafer relative to a wafer placement unit according to a fifth embodiment of the present disclosure. The image processing unit 105 calculates the position of the center of gravity of the wafer placement unit 102 when observed from directly above, based on an image (second image) 902 obtained by observing the wafer placement unit 102 from directly above. The image processing unit 105 calculates the position of the center of gravity of the wafer 106 when observed from directly above, based on an image (first image) 906 obtained by observing the wafer 106 from directly above. By comparing the calculated positions of the center of gravity of the wafer placement unit 102 and the wafer 106, the image processing unit 105 can detect the amount of misalignment of the wafer 106 relative to the wafer placement unit 102. That is, in this method, the misalignment detection device 105 detects the amount of misalignment of the sample 106 relative to the placement unit 102 based on the position of the center of gravity of the sample 106 calculated using the first image 901 and the position of the center of gravity of the placement unit 102 calculated using the second image 902. For example, if the center of gravity of the wafer placement part is calculated as X: 2600.123, Y: 1900.456 pixels in image 902 and the center of gravity of the wafer is calculated as X: 2650.789, Y: 1910.012 pixels in image 906, then the displacement is 50.666 pixels in the X direction and 9.556 pixels in the Y direction. If one pixel is 0.1 mm, the displacement in the X direction can be calculated as 5.666 mm and the displacement in the Y direction as 0.9566 mm. This method using the center of gravity position uses a large number of pixels for position calculation, enabling more accurate calculation of the displacement amount. However, disturbances such as uneven brightness or blurring in the image can cause errors in the selection of the wafer placement part and wafer area. For this reason, it is preferable to select an appropriate position detection image processing method or to perform multiple position detection image processing methods depending on the environment within the chamber and the acquired image.

[0022] 10 is a diagram illustrating an example of a detection method for detecting misalignment of a wafer relative to a wafer placement unit according to a sixth embodiment of the present disclosure. As shown in (a) of FIG. 10 , the centers of the imaging device 1003 and the wafer placement unit 102 may be misaligned due to the mounting accuracy of the imaging device 1003 or the imaging device holding member 1004, misalignment of the lens center of the imaging device 1003, or intentional setting. In such a case, as shown in (b) and (c) of FIG. 10 , particularly when the wafer 106 is positioned above, the left region 1007 a and the right region 1007 b, which should be equal if the centers of the wafer 106 and the wafer placement unit 102 are aligned, may appear to be misaligned in the image. At this time, the image processing unit 105 calculates the amount of misalignment between the imaging device 1003 and the wafer mounting unit 102 based on an image (second image) 1002 obtained by observing the wafer mounting unit 102 from directly above, as shown in FIG. 10D , and corrects the position of the imaging device 1003 to detect the amount of misalignment of the wafer 106 relative to the wafer mounting unit 102. In other words, in this method, the misalignment detection device 105 calculates a correction amount for correcting the position of the imaging device 1003, which images the sample 106 or the mounting unit 102, using the second image 1002. After the calculated correction amount is applied to the position of the imaging device 1003, the amount of misalignment of the sample 106 relative to the mounting unit 102 is detected. This makes it possible to detect the amount of misalignment of the wafer even when the centers of the imaging device 1003 and the wafer mounting unit 102 are misaligned. Furthermore, by acquiring multiple images while changing the height of the wafer 106, more precise position correction that also accommodates the tilt of the imaging device 1003 is possible.

[0023] Seventh Embodiment Fig. 11 is a diagram illustrating an example of a detection method for detecting misalignment of a wafer relative to a wafer mounting portion according to a seventh embodiment of the present disclosure. As shown in Fig. 11A, a plasma processing apparatus 100 may be provided with a plurality of imaging devices 1103a, 1103b. That is, the plasma processing apparatus 100 further includes a plurality of imaging devices 1103a, 1103b arranged above the mounting portion 102 and configured to capture images of the sample 106 or the mounting portion 102. As shown in Fig. 11B, the imaging devices 1103a, 1103b acquire enlarged images (second images) 1102a, 1102b of the outer periphery of the wafer mounting portion 102 and enlarged images (first images) 1106a, 1106b of the outer periphery of the wafer 106, respectively. An image processing unit 1105 then performs, for example, differential processing to generate images 1107a, 1107b. From the profiles of these two images 1107a and 1107b, it is possible to detect the amount of misalignment of the wafer 106 with respect to the wafer placement part 102. By acquiring an enlarged image in this manner, one pixel corresponds to, for example, 0.01 mm, making it possible to detect the amount of misalignment of the wafer with higher accuracy.

[0024] Eighth Embodiment FIG. 12 illustrates an example of a detection method for detecting misalignment of a wafer relative to a wafer placement unit according to an eighth embodiment of the present disclosure. As shown in FIGS. 12A and 12B, the plasma processing chamber 101 may have structures (a quartz top plate 1210 and a quartz shower plate 1211) transparent to visible light disposed between the placement unit 102 and the imaging device 103. Examples of structures transparent to visible light include the quartz top plate 1210 that maintains a vacuum and the quartz shower plate 1211 that has gas holes, and the plasma processing chamber 101 may have a plurality of such structures. Distortion may occur in the quartz top plate 1210 and the quartz shower plate 1211 due to aging or other factors. In this case, as shown in FIGS. 13A and 13B, distortion may also occur in an image (second image) 1302 obtained by observing the wafer placement unit 102 from directly above and an image (first image) 1306 obtained by observing the wafer 106 from directly above. In this case, the image processing unit 105 determines the amount of distortion based on the deviation of the acquired shape of the wafer placement unit 102 and the shape of the wafer 106 from a perfect circle, and the slope of the profile of the difference image 1307 shown in FIG. 13C, and performs correction, thereby detecting the amount of wafer misalignment. Furthermore, if the distortion exceeds a certain level and correction is difficult, a warning to that effect may be issued. In other words, in this method, the misalignment detection device 105 calculates the influence of the structures (1210, 1211) on the first image 1306 or the second image 1302. Then, after correcting the calculated influence of the structures (1210, 1211), the amount of misalignment of the sample 106 with respect to the placement unit 102 is detected.

[0025] 14 is a diagram illustrating an example of a correction method for correcting a wafer misalignment relative to a wafer placement unit according to a ninth embodiment of the present disclosure. As shown in (a) of FIG. 14 , the wafer 106 is held by a transport mechanism 407 controlled by a control unit 1412 and placed above the wafer placement unit 102. As shown in (b) of FIG. 14 , the image processing unit 105 creates a differential image 1407a between an image (second image) of the entire surface of the wafer placement unit 102 observed from directly above, acquired by the imaging device 1403 before the wafer 106 is loaded into the plasma processing chamber 101, and an image (first image) of the entire surface of the wafer 106 held by the transport mechanism 407 and placed above the wafer placement unit 102 observed from directly above, acquired by the imaging device 1403, and displays the differential image 1407a on the display unit 1413. The image (first image) of the entire surface of the wafer 106 observed from directly above is updated at a rate of, for example, 30 fps, and the differential image 1407a is also updated accordingly. Therefore, by operating the transport mechanism 407 using the control unit 1412, a difference image 1407a at the current position of the wafer 106 is displayed in real time on the display unit 1413. By operating the control unit 1412 so that the difference image 1407b is displayed, it becomes possible to control the position of the wafer 106 while constantly checking the amount of misalignment. It is also advisable to simultaneously display the current amount of misalignment on the display unit. This makes it possible to quickly correct the misalignment of the wafer relative to the wafer placement unit.

[0026] That is, this correction method relates to a positional deviation correction method for detecting a positional deviation of a sample 106 relative to a mounting part 102 in a plasma processing apparatus 100 equipped with a sample stage having a mounting part 102 on which the sample 106 is mounted, and correcting the detected positional deviation of the sample 106 relative to the mounting part 102. This positional deviation correction method includes a step of detecting the positional deviation of the sample 102 relative to the mounting part 102 based on a difference image (1407a) between a first image including the outer periphery of the sample 106 and a second image including the outer periphery of the mounting part, and a step of correcting the detected positional deviation of the sample 106 relative to the mounting part 102 by operating a control unit 1412 so as to display a difference image 1407b.

[0027] Tenth Embodiment Fig. 15 is a diagram illustrating an example of a correction method for correcting misalignment of a wafer relative to a wafer placement unit according to a tenth embodiment of the present disclosure. In the ninth embodiment (Fig. 14), the centers of the imaging device 1403 and the wafer placement unit 102 may be misaligned due to the installation accuracy of the imaging device 103 or the imaging device holding member 104, misalignment of the lens center of the imaging device 1403, or intentional setting. As shown in the sixth embodiment (Fig. 10), correction is performed based on the amount of misalignment between the imaging device 1403 and the wafer placement unit 102, and an appropriate current amount of misalignment is displayed. In this case, a discrepancy may occur between the displayed amount of misalignment and the difference image 1507a, potentially confusing the operator. Therefore, the image processing unit 105 uses the center misalignment amount between the imaging device 1403 and the wafer mounting unit 102 to correct an image (first image) of the entire surface of the wafer 106 observed from directly above, and then creates a difference image 1507b and displays it on the display unit 1413. This allows the operator to quickly correct the misalignment of the wafer relative to the wafer mounting unit without confusion. The steps of the tenth embodiment of the present disclosure can be added to the misalignment amount correction method described in the ninth embodiment. In other words, the misalignment amount correction method of the ninth embodiment further includes a step of calculating a correction amount for correcting the position of the imaging device 1003 that captures the sample 106 or the mounting unit 102 using the second image, and performing differential processing between the first image reflecting the calculated correction amount and the second image reflecting the calculated correction amount.

[0028] The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

[0029] 101: plasma processing chamber, 102: wafer placement section, 103: imaging device, 104: imaging device holding member, 105: image processing section, 106: wafer, 107: vacuum processing chamber, 109: exhaust device.

Claims

1. A plasma processing apparatus comprising a sample stage having a placement portion on which a sample is placed, and a displacement amount detection device that detects a displacement amount of the sample with respect to the placement portion, wherein the displacement amount of the sample with respect to the placement portion is detected by the displacement amount detection device based on a first image including an outer peripheral portion of the sample and a second image including an outer peripheral portion of the placement portion.

2. The plasma processing apparatus according to claim 1, wherein the first image is an image including an outer peripheral portion of the sample disposed above the placement portion.

3. The plasma processing apparatus according to claim 1, further comprising a transport mechanism for transporting the sample, wherein the sample is held above the placement portion by the transport mechanism.

4. The plasma processing apparatus according to claim 1, wherein the sample is placed on the placement portion.

5. The plasma processing apparatus according to any one of claims 1 to 4, wherein the first image is an image including the entire sample, and the second image is an image including the entire placement portion.

6. The plasma processing apparatus according to any one of claims 1 to 4, wherein the displacement amount detection device performs differential processing on the first image and the second image, and detects the displacement amount of the sample with respect to the placement portion based on the differentially processed image.

7. The plasma processing apparatus according to claim 5, wherein the displacement amount detection device detects the displacement amount of the sample with respect to the placement portion based on the center of gravity position of the sample calculated using the first image and the center of gravity position of the placement portion calculated using the second image.

8. The plasma processing apparatus according to any one of claims 1 to 4, wherein a correction amount for correcting the position of an imaging device that images the sample or the placement portion is calculated by the displacement amount detection device using the second image, and after correcting the position of the imaging device by the calculated correction amount, the displacement amount of the sample with respect to the placement portion is detected.

9. The plasma processing apparatus according to any one of claims 1 to 4, further comprising an imaging device that is disposed above the placement unit and images the sample or the placement unit.

10. The plasma processing apparatus according to any one of claims 1 to 4, further comprising an imaging device that images the sample or the placement unit, and a transparent structure disposed between the placement unit and the imaging device. When the influence of the structure on the first image or the second image is calculated by the misalignment amount detection device and the calculated influence of the structure is corrected, the misalignment amount of the sample with respect to the placement unit is detected. The plasma processing apparatus is characterized by this.

11. In a displacement amount detection device for detecting the displacement amount of a sample with respect to a placement unit in a plasma processing apparatus including a sample stage having a placement unit on which the sample is placed, the displacement amount of the sample with respect to the placement unit is detected based on a first image including the outer peripheral portion of the sample and a second image including the outer peripheral portion of the placement unit. The displacement amount detection device is characterized by this.

12. The displacement amount detection device according to claim 11, wherein the first image is an image including the outer peripheral portion of the sample disposed above the placement unit. The displacement amount detection device is characterized by this.

13. In a displacement amount correction method for detecting the displacement amount of a sample with respect to a placement unit in a plasma processing apparatus including a sample stage having a placement unit on which the sample is placed and correcting the detected displacement amount of the sample with respect to the placement unit, a step of detecting the displacement amount of the sample with respect to the placement unit based on a first image including the outer peripheral portion of the sample and a second image including the outer peripheral portion of the placement unit, and a step of correcting the detected displacement amount of the sample with respect to the placement unit. The displacement amount correction method is characterized by having these steps.

14. The displacement amount correction method according to claim 13, further comprising a step of calculating a correction amount for correcting the position of the imaging device that images the sample or the placement unit using the second image, and performing a difference process between the first image reflecting the calculated correction amount and the second image reflecting the calculated correction amount. The displacement amount correction method is characterized by this.

Images