JP2009109263A - Apparatus and method for inspection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection apparatus capable of inspecting pattern irregularities, defects, or the lik, using a single apparatus. <P>SOLUTION: The inspection apparatus 10 is an inspection apparatus for inspecting a pattern formed on a sample 30 and includes a light source 11 for irradiating illumination light to the sample 30; a Digital Micromirror Device (DMD) 13, arranged in an optical Fourier transfer plane to the pattern of the sample 30 for reflecting diffracted light or scattered light from the sample 30; and a photodetector 17, arranged at a position conjugate to DMD 13 for receiving the light reflected at DMD 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inspection apparatus and an inspection method for inspecting patterns such as wafers and masks used in semiconductor manufacturing processes.

  In photomasks and semiconductor wafers used in semiconductor manufacturing processes, a predetermined pattern is repeatedly formed on a substrate. Conventionally, pattern diffraction, foreign matter, defects, etc. are inspected using diffracted light (for example, first-order diffracted light) generated from a repetitive pattern formed on the surface of these masks (hereinafter referred to as “sample”). An inspection apparatus has been proposed (see, for example, Patent Documents 1 and 2). Since the diffraction efficiency is different between the defective portion and the normal portion on the sample surface, a difference in brightness appears in the image based on the diffracted light from the repetitive pattern, and the defective portion can be identified by the brightness.

Patent Document 3 discloses an inspection apparatus in which a mirror array device is arranged at a conjugate point with the pupil position of an objective lens in order to change the illumination method according to the pattern formed on the sample. In the inspection apparatus described in Patent Document 3, an imaging device is arranged at a position conjugate with a sample, and a pattern defect is inspected by capturing an image of the sample projected by the objective lens with the imaging device. Yes.
Japanese Patent Laid-Open No. 10-232122 JP 2001-141657 A JP 2006-23221 A

  Conventionally, in the case of defect or foreign matter inspection, light scattered in a specific angle range other than the angle of diffracted light from a pattern has been detected. On the other hand, when inspecting the pattern line width unevenness, the pattern line width unevenness is detected by monitoring the intensity change of the diffracted light of a specific order among the diffracted light from the pattern. For this reason, inspection of pattern defects and line width unevenness cannot be realized by a single inspection apparatus.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to perform inspection that can realize inspection of pattern unevenness and inspection of defects or foreign matters with a single inspection apparatus. An apparatus and an inspection method are provided.

  An inspection apparatus according to a first aspect of the present invention is an inspection apparatus for inspecting a pattern formed on a sample, and a light source for irradiating the sample with illumination light, and an optical Fourier transform for the pattern of the sample A digital micromirror device (DMD) that is disposed on a surface and reflects diffracted light or scattered light from the sample; and a photodetector that is disposed at a position conjugate with the DMD and receives light reflected by the DMD. Is provided. Thereby, pattern unevenness inspection and inspection of defects and the like can be realized with one apparatus.

  The inspection apparatus according to a second aspect of the present invention is the inspection apparatus according to the above aspect, wherein the photodetector receives a plurality of orders of diffracted light, and the pixels that receive the diffracted lights are in accordance with the orders of the plurality of diffracted lights. It is characterized by being different. Thereby, it is possible to determine the diffracted light of the order in which the change in the diffracted light intensity due to unevenness or the like is large.

  In the inspection apparatus according to the third aspect of the present invention, in the above inspection apparatus, when inspecting the unevenness of the pattern of the sample, among the plurality of orders of diffracted light, the order of diffracted light having a high intensity is used. The incident DMD pixel is in an off state. Thereby, inspection sensitivity can be improved.

  In the inspection apparatus according to the fourth aspect of the present invention, in the above-described inspection apparatus, when inspecting the pattern unevenness of the sample, the intensity change caused by the unevenness among the diffracted lights of the plurality of orders is large. The DMD pixel on which the diffracted light of the order other than the diffracted light of the order is incident is in an off state. Thereby, inspection sensitivity can be improved.

  In the inspection apparatus according to the fifth aspect of the present invention, in the inspection apparatus described above, the diffracted light of the plurality of orders received by the photodetector emphasizes the feature of unevenness of the pattern of the sample. , Different weighting coefficients are set according to the orders. Thereby, inspection sensitivity can be improved.

  An inspection apparatus according to a sixth aspect of the present invention is the inspection apparatus according to the above aspect, wherein a plurality of filter matrices in which different weighting coefficients are set for each of the plurality of orders of diffracted light received by the photodetector. It is to be prepared. Thereby, a filter matrix can be changed as needed.

  The inspection apparatus according to a seventh aspect of the present invention is the above-described inspection apparatus, wherein the sample of the light receiving system including the DMD and the photodetector is configured so that the order of the diffracted light incident on the photodetector can be changed. The angle with respect to can be changed. Thereby, inspection sensitivity can be improved.

  In the inspection apparatus according to the eighth aspect of the present invention, in the inspection apparatus described above, when the defect of the pattern of the previous sample is inspected, the pixel irradiated with the diffracted light from the sample pattern of the DMD is , Being in an off state. Thereby, it is possible to accurately inspect the sample for defects.

  The inspection method according to the ninth aspect of the present invention is an inspection method for inspecting a pattern formed on a sample, irradiating the sample with illumination light, and diffracted light or scattered light from the sample, The light reflected by the digital micromirror device (DMD) disposed on the optical Fourier transform plane for the sample pattern and reflected by the DMD is received by a photodetector disposed at a position conjugate with the DMD. To do. As a result, it is possible to realize inspection of pattern unevenness and inspection of defects and the like.

  In the inspection method according to a tenth aspect of the present invention, in the above inspection method, the photodetector receives a plurality of orders of diffracted light, and receives light at different pixels according to the orders of the plurality of diffracted lights. To do. Thereby, inspection sensitivity can be raised.

  In the inspection method according to the eleventh aspect of the present invention, in the above inspection method, when inspecting the pattern unevenness of the sample, among the plurality of orders of diffracted light, the order of diffracted light having a high intensity The incident DMD pixel is turned off. Thereby, inspection sensitivity can be improved.

  In the inspection method according to the twelfth aspect of the present invention, in the inspection method described above, when the unevenness of the pattern of the sample is inspected, the intensity change caused by the unevenness among the diffracted lights of the plurality of orders is large. The DMD pixel on which the diffracted light of the order other than the diffracted light of the order enters is turned off. Thereby, inspection sensitivity can be improved.

  In the inspection method according to the thirteenth aspect of the present invention, in the inspection method described above, the diffracted light of the plurality of orders received by the photodetector emphasizes the feature of unevenness of the pattern of the sample. A different weighting coefficient is set according to the order. Thereby, inspection sensitivity can be improved.

  An inspection method according to a fourteenth aspect of the present invention is the inspection method described above, wherein the intensity change of the diffracted light is changed using a different weighting factor for each of the plurality of orders of diffracted light received by the photodetector. To emphasize. Thereby, inspection sensitivity can be improved.

  An inspection method according to a fifteenth aspect of the present invention is the above inspection method, wherein the order of the diffracted light incident on the photodetector is changed by changing the position of the light receiving system including the DMD and the photodetector with respect to the sample. To change. Thereby, inspection sensitivity can be improved.

  In the inspection method according to the sixteenth aspect of the present invention, in the inspection method described above, when the defect of the pattern of the previous sample is inspected, the pixel irradiated with the diffracted light from the sample pattern of the DMD is used. Turn off. Thereby, it is possible to accurately inspect the sample for defects.

  ADVANTAGE OF THE INVENTION According to this invention, the inspection apparatus and inspection method which can implement | achieve the test | inspection of the nonuniformity of a pattern and the test | inspection of a defect or a foreign material with one test | inspection apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, the same reference numerals indicate substantially the same contents.

  An inspection apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a basic configuration of the inspection apparatus 10. The inspection apparatus 10 according to the present embodiment performs inspection of defects or foreign matters on a sample in which a repeated pattern is formed on a substrate, and inspection of pattern line width unevenness. In addition, even if it determines with a nonuniformity of a pattern in micro inspections, such as a defect inspection, a slight dimensional shift of a pattern generate | occur | produces and it is determined as a defective product by visual macro inspection.

  In the following description, an inspection apparatus that inspects the sample 30 on which a repeated pattern is formed on a wafer will be described as an example. The repeated pattern is an L / S (line and space) pattern in which lines and spaces (concave and convex portions) that are long and parallel in one direction are arranged at regular intervals. However, the present invention is not limited to this, and can be applied to pattern inspection of a photomask, a liquid crystal display panel, or the like.

  As shown in FIG. 1, the inspection apparatus 10 includes a light source 11, lenses 12, 14, and 16, a digital micromirror device (DMD) 13, a mirror 15, a photodetector 17, and a processing device 20. When inspecting unevenness, the inspection apparatus 10 according to the present embodiment irradiates a repetitive pattern formed on the sample 30 with coherent light, and a diffracted light pattern (Fourier pattern) on a Fourier transform plane obtained by the lens. ), The pattern unevenness is inspected. On the other hand, when inspecting a defect, a foreign object, etc., it is performed by detecting scattered light from the defect or the like without detecting diffracted light due to the pattern of the sample 30.

  Although not shown here, the sample 30 is adsorbed and fixed on the XY stage. By driving the XY stage with a motor or the like, the sample 30 can be scanned with the light beam emitted from the light source 11.

  The light source 11 emits illumination light L01 that is coherent light to the sample 30. As the light source 11, a laser or the like that emits coherent light can be used. For example, a laser beam having a wavelength of 405 nm is incident on the sample 30 in an incident light. In the present embodiment, the beam diameter of the illumination light L01 is, for example, 0.2 to 0.3 mm. About 10 patterns of the sample 30 are included in the light beam of the illumination light L01. In the present invention, since the sample 30 is irradiated with substantially parallel light, it is possible to accurately inspect for unevenness regardless of the focus position.

When the pitch of the repetitive pattern on the sample 30 is d, the incident angle of the illumination light is θi, the diffraction angle when the order of the diffracted light is m is θm, and the wavelength of the incident light is λ, the following equation is generally satisfied. Known.
d (sin θm ± sin θi) = mλ (m = 0, ± 1,...)
Here, the zero-order diffracted light (direct light) has relatively little fine defect information. For this reason, it is necessary to detect a diffracted light of an order larger in absolute value than the 0th order diffracted light. Accordingly, as shown in FIG. 1, the fourth to sixth order diffracted light is incident on the lens 12 here. Diffracted light L02 from the repetitive pattern of the sample 30 interferes with each other and passes through the lens 12, whereby a diffracted light pattern (Fourier pattern) depending on the repetitive period is formed on the Fourier transform plane.

  As can be seen from the above equation, the diffraction order m and the diffraction angle θm vary depending on the pitch d of the repetitive pattern. Further, in the example of FIG. 1, diffracted light of 4th to 6th order is made incident on the lens 12, but the lower order (1st to 3rd order) can be inspected with higher sensitivity or higher. In some cases, the order can be examined with higher sensitivity. Therefore, as shown in FIG. 2, the light receiving systems such as the DMD 13 and the photodetector 17 are provided so as to be rotatable around the inspection region O of the sample 30. That is, the light receiving system including the DMD 13 and the photodetector 17 is provided so that the angle with respect to the sample 30 can be changed. Thereby, the order of the diffracted light to be received can be selected, and the sample 30 can be inspected with higher sensitivity. In FIG. 2, for example, the illumination light L01 emitted from the light source 11 may be bent by a mirror or the like to irradiate the sample 30 so that the light receiving system and the light source 11 do not interfere with each other.

  A DMD 13 is disposed on the optical Fourier transform plane for the pattern of the sample 30. That is, the DMD 13 is disposed at the pupil position of the light receiving system. Accordingly, a diffracted light pattern based on the repetitive pattern of the sample 30 is formed on the DMD 13. The DMD 13 has a configuration in which a large number of micromirror surfaces (micromirrors) are arranged in a plane. As the DMD 13, for example, a product manufactured by Texas Instruments Incorporated can be used. Each micromirror corresponds to a pixel. The DMD 13 is used as a reflection mirror that can control on / off of each micromirror at a high speed for each pixel. The state in which the micromirrors of the DMD 13 are controlled so that the reflected light is incident on the lens 14 is the on state, and the state in which the micromirrors are controlled so that the reflected light is not incident on the lens 14 is the off state. Therefore, when the micromirror is on, the diffracted light from the sample 30 is reflected in the direction of incidence on the lens 14. On the other hand, when the micromirror is off, the diffracted light from the sample 30 is reflected in a direction not incident on the lens 14.

  The diffracted light L03 reflected to the lens 14 side by the DMD 13 enters the lens 14 and is collected on the mirror 15. The light L04 reflected by the mirror 15 passes through the lens 16 and enters the photodetector 17. The photodetector 17 receives the light reflected by the DMD 13 and converts it into an electrical signal. The photodetector 17 is arranged at a position conjugate with the DMD 13. That is, the DMD 13 and the photodetector 17 are both arranged at the pupil position of the light receiving system. For example, a one-dimensional NMOS line sensor is preferably used as the photodetector 17.

  As described above, in the present embodiment, the pattern formed on the sample 30 is a line and space pattern. For this reason, the diffracted lights of a plurality of orders due to the pattern of the sample 30 each travel in a specific direction. The pixels of the photodetector 17 are arranged in a direction in which a plurality of orders of diffracted light from the pattern of the sample 30 are emitted. Further, the pixels of the DMD 13 and the pixels of the photodetector 17 are arranged to correspond to each other. That is, a certain order of diffracted light is reflected by a specific pixel of the DMD 13 and detected by a specific pixel of the photodetector 17. By measuring changes in the intensity of the diffracted light of a plurality of orders detected by the photodetector 17, the unevenness inspection is performed. For example, the pattern line width unevenness is inspected based on the difference between the diffracted light intensity from the reference pattern serving as a reference and the measured diffracted light intensity from the pattern of the sample 30. Thus, by arranging the line sensors in the direction in which the diffracted light is emitted, the number of light receiving pixels can be reduced, so that the inspection speed can be increased. Note that an area sensor using a two-dimensional CCD element or the like can be used as the photodetector 17.

  On the other hand, when a defect or foreign matter inspection is performed, the DMD 13 pixel at the position where the diffracted light from the pattern of the sample 30 is projected is turned off. Thereby, the diffracted light due to the pattern of the sample 30 does not enter the photodetector 17. For this reason, when there is a defect other than the pattern, foreign matter, or the like, the scattered light due to the defect or the like is reflected in the direction of the lens 14 by the pixel of the DMD 13 in the on state. Therefore, the scattered light due to the defect or the like is detected by the photodetector 17, and the defect or the like is inspected.

  A signal corresponding to the light received by the photodetector 17 is supplied to the processing device 20. FIG. 3 schematically shows the configuration of the processing apparatus 20. As illustrated in FIG. 3, the processing device 20 includes a scan control unit 21, a DMD control unit 22, a defect determination unit 23, a filter matrix selection unit 24, a calculation unit 25, and a nonuniformity determination unit 26. The scan control unit 21 controls the relative position between the stage on which the sample 30 is placed and the light emitted from the light source 11. The DMD control unit 22 switches on / off of each pixel of the DMD 13. The defect determination unit 23 determines the presence or absence of a defect based on the optical signal received by the photodetector 17 when inspecting a defect or a foreign object.

  In the filter matrix selection unit 24, a plurality of filter matrices for weighting each order of diffracted light are set. The filter matrix selection unit 24 selects an optimal filter matrix based on the optical signal from the photodetector 17. For example, when unevenness is detected, a filter matrix having a large coefficient is selected to weight the diffracted light of the order having a large intensity change with respect to the line width. Further, when one of the diffracted lights incident on the photodetector 17 is too strong and becomes saturated, the coefficient corresponding to the signal from the pixel of the photodetector 17 corresponding to the diffracted light is zero. Can be selected. As a result, the light receiving range can be expanded, and unevenness can be detected with higher sensitivity. The calculation unit 25 performs calculation processing using the filter matrix selected by the filter matrix selection unit 24. The unevenness determination unit 26 determines unevenness of the sample 30 based on the signal weighted by the calculation unit 25.

  Here, a method for inspecting the sample 30 using the above-described inspection apparatus 10 will be described. As described above, the inspection apparatus 10 according to the present embodiment realizes the inspection of the unevenness of the pattern formed on the sample 30 and the inspection of defects or foreign matters with a single apparatus. First, a method for inspecting pattern unevenness of the sample 30 will be described. The unevenness detection method according to the present invention is a feature extraction of a Fourier pattern.

First, the filter matrix is set first. A plurality of filter matrices can be set. The filter matrix setting method will be described separately for (1) when there is a sample wafer with a CD (critical dimension), and (2) when there is no sample wafer with a CD.
(1) When there is a sample wafer on which a CD is shaken First, a sample wafer exposed by slightly changing the dose (exposure amount) between shots is prepared. If a positive resist is formed on the wafer, the pattern line width after development is changed by changing the dose.

  Then, the entire surface of the sample wafer is scanned, and data on the diffracted light intensity is captured. At this time, all the pixels of the DMD 13 are turned on. Then, dies having different pattern line widths are designated and the patterns are compared. When the difference between these diffracted light intensities is taken, the difference becomes large with a specific order of diffracted light. Therefore, the unevenness inspection can be performed with high sensitivity by monitoring the intensity change of the diffracted light of this order. A filter matrix is set for weighting data from the pixels of the photodetector 17 on which the diffracted light of this order is incident. That is, the filter matrix that emphasizes the feature of the pattern line width error is automatically determined.

  When the pattern line width changes, the intensity of diffracted light of a certain order may become large or strong, or it may become weak. Therefore, a positive or negative coefficient is applied to the diffracted light having such a large change so as to emphasize the change. For example, if the fourth-order diffracted light intensity does not change even when the pattern line width is changed, the coefficient for the fourth-order diffracted light is set to zero. When the fifth-order diffracted light intensity changes greatly when the pattern line width is changed, the fifth-order diffracted light is multiplied by a large coefficient corresponding thereto. Thereby, a light reception range can be expanded and inspection sensitivity can be improved.

(2) When there is no sample wafer on which the CD is shaken Create an intensity map of diffracted light from each order of diffracted light. That is, the intensity distribution of the diffracted light from the sample 30 received by each pixel of the photodetector 17 is obtained. Furthermore, the abnormal region and the normal region are manually detected by using the sum and difference between the intensity maps of the diffracted lights as supplementary information. That is, the region where the diffracted light intensity is not changed compared to the other observation regions of the sample 30 is determined as a normal region, and the changing region is determined as an abnormal region. Then, as described above, a filter matrix that automatically emphasizes the features of the abnormal region is set automatically.

  After determining the filter matrix as described above, the actual sample 30 is inspected for unevenness. Specifically, first, the entire surface of the sample 30 and the reference wafer is scanned, and the respective diffracted light patterns are captured. Then, the difference between the diffracted light intensity of the sample 30 and the diffracted light intensity of the reference wafer is obtained. Thereafter, arithmetic processing is performed using the filter matrix selected by the filter matrix selection unit 24 of the processing device 20 to emphasize features to be detected. Then, in the unevenness determination unit 26, a part having a large difference in diffracted light intensity from the reference, a singular point, or the like is determined as an abnormal part. As described above, in the present invention, since the diffracted light intensities of the reference wafer and the sample 30 are compared, the influence of the alignment error is small compared with the conventional Die to Die and Die to Database inspection methods.

  In the case of an actual semiconductor wafer, there are a peripheral circuit portion and a repeated pattern region which is an inspection target region. Therefore, after scanning the entire surface of the semiconductor wafer and before performing the filtering process, it is possible to separate the peripheral circuit portion and the inspection target region using a projection or a histogram. Further, when taking in the diffracted light pattern of the reference wafer, the intensity of the diffracted light of a specific order may be too strong and the corresponding pixel of the photodetector 17 may be saturated. In this case, the corresponding pixel of the DMD 13 can be turned off, and the coefficient of the filter matrix can be set to zero. In this case, when the sample 30 is inspected, the unevenness inspection of the sample 30 is started while the DMD 13 pixel is kept in the OFF state. In addition, when measuring the reference diffracted light pattern, the sensitivity of the photodetector 17 may be changed so as not to be saturated, and the diffracted light pattern of the sample 30 may be measured in this state.

  A pixel of the DMD 13 on which a plurality of orders of diffracted light is incident on the photodetector 17 to determine orders of diffracted light having a large intensity change due to unevenness, and orders of orders other than the orders of diffracted light enter. May be turned off.

  Thus, according to the present invention, the variation in the diffracted light intensity caused by the unevenness is large, and the unevenness is inspected using the diffracted light of the order with high sensitivity. For this reason, a very sensitive unevenness inspection can be performed. In addition, since the filter matrix can apply a large coefficient to the diffracted light intensity of a specific order, the sensitivity can be further improved. Furthermore, the pixel of DMD 13 corresponding to the pixel whose intensity of diffracted light is strong and the output of photodetector 17 is saturated can be turned off. Thereby, the dynamic range can be expanded. Note that the coefficient of the filter matrix for the output from the pixel of the photodetector 17 corresponding to the pixel of the DMD 13 in the off state may be zero.

  Next, a method for inspecting defects, foreign matters and the like using the inspection apparatus 10 will be described. The defect inspection method according to the present invention is a dark field scattered light detection method. First, a wafer having no defect or the like is illuminated from the light source 11 substantially vertically. The light diffracted by the wafer pattern and reflected by the DMD 13 is received by the photodetector 17. At this time, the pixel of the DMD 13 on which the diffracted light from the repeated pattern of the wafer is incident is turned off. That is, the pixels of the photodetector 17 in the portion where the strong diffracted light from the repetitive pattern of the wafer is incident are masked by the DMD pixels in the off state. That is, the DMD 13 is controlled to function as a spatial filter that blocks the pixels on which the diffracted light from the pattern of the sample 30 is incident. Specifically, the pixel where the diffracted light from the pattern of the sample 30 is incident is controlled so that the reflected light is not incident on the lens 14, and the other pixels are controlled so that the reflected light is incident on the lens 14. To do. Therefore, the diffracted light from the normal pattern of the wafer having no defect is not detected by the photodetector 17.

  Then, the sample 30 is illuminated substantially vertically from the light source 11 in the same manner while the pixels of the DMD 13 on which the diffracted light from the normal pattern is incident are in the OFF state. The entire surface of the sample 30 is scanned, and a map of the sum of the intensities of the light received by the pixels of the photodetector 17 not masked by the off-state pixels of the DMD 13 is obtained. When there is a pattern defect or foreign matter on the sample 30, the light scattered from the defect or the like is scattered at an angle shifted from the diffracted light from the pattern. For this reason, scattered light from a defect or the like is received by the photodetector 17. Therefore, a portion having a high signal intensity is determined as a pattern defect or a foreign object. As described above, after the entire surface of the semiconductor wafer is scanned, the peripheral circuit portion and the inspection target region can be separated using a projection or a histogram.

  As described above, according to the present invention, it is possible to realize inspection of pattern unevenness and inspection of defects or foreign matters with a single inspection apparatus. Further, by controlling on / off of the DMD 13 arranged at the pupil position of the light receiving system, the dynamic range can be expanded, and the inspection accuracy can be improved. The present invention is applicable to an appearance inspection apparatus for inspecting a semiconductor wafer having a repetitive pattern, a semiconductor memory photomask, a liquid crystal display panel, and the like.

  In the above description, the case where the pattern line width unevenness is detected has been described. However, the present invention is not limited to this. For example, by examining the change in the diffracted light intensity with a pattern formed in advance, and selecting a filter matrix having a large coefficient corresponding to the diffracted light of the order with a large intensity change, the film thickness of the resist formed on the substrate, It is also possible to determine the type of unevenness such as a profile change.

  In the above-described embodiment, the DMD 13 is disposed on the Fourier transform plane for the pattern of the sample 30. However, the present invention is not limited to this. For example, a liquid crystal optical switch that can easily control the direction of the reflected light can be used.

It is a figure showing composition of inspection device 10 concerning an embodiment. It is a figure which shows a state when the light-receiving system of the inspection apparatus 10 which concerns on embodiment is moved. It is a block diagram which shows the structure of the processing apparatus 20 which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inspection apparatus 11 Light source 12, 14, 16 Lens 13 DMD
DESCRIPTION OF SYMBOLS 15 Mirror 17 Optical detector 20 Processing apparatus 21 Scan control part 22 DMD control part 23 Defect determination part 24 Filter matrix selection part 25 Calculation part 26 Unevenness determination part 30 Sample L01 Illumination light L02, L03, L04 Diffracted light

Claims (16)

An inspection apparatus for inspecting a pattern formed on a sample,
A light source for illuminating the sample with illumination light;
A digital micromirror device (DMD) disposed on an optical Fourier transform plane for the pattern of the sample and reflecting diffracted or scattered light from the sample;
A photodetector disposed at a position conjugate with the DMD and receiving light reflected by the DMD;
An inspection apparatus comprising: The photodetector receives a plurality of orders of diffracted light,
The inspection apparatus according to claim 1, wherein pixels that receive light differ depending on the orders of the plurality of diffracted lights. When inspecting the unevenness of the pattern of the sample,
The inspection apparatus according to claim 2, wherein a pixel of the DMD to which a diffracted light of a higher intensity among the plurality of orders of diffracted light is incident is in an off state. When inspecting the unevenness of the pattern of the sample,
3. The pixel of the DMD to which a diffracted light of an order other than a diffracted light having a large intensity change due to unevenness among the plurality of orders of diffracted light is in an off state. 3. The inspection apparatus according to 3.   The diffracted light of the plurality of orders received by the photodetector is set with a different weighting coefficient depending on the order so as to emphasize the feature of unevenness of the pattern of the sample. Item 5. The inspection device according to any one of Items 2 to 4.   The inspection apparatus according to claim 5, further comprising a plurality of filter matrices each having a different weighting coefficient set for each of the plurality of orders of diffracted light received by the photodetector.   The inspection apparatus according to claim 1, wherein an angle of the light receiving system including the DMD and the photodetector with respect to the sample can be changed so that the order of the diffracted light incident on the photodetector can be changed. When inspecting the pattern defect of the previous sample,
The inspection apparatus according to claim 1, wherein a pixel irradiated with diffracted light from the sample pattern of the DMD is in an off state. An inspection method for inspecting a pattern formed on a sample,
Illuminating the sample with illumination light;
The diffracted light or scattered light from the sample is reflected by a digital micromirror device (DMD) disposed on an optical Fourier transform surface with respect to the pattern of the sample,
An inspection method in which the light reflected by the DMD is received by a photodetector arranged at a position conjugate with the DMD. The photodetector receives a plurality of orders of diffracted light,
The inspection method according to claim 9, wherein light is received by different pixels according to the orders of the plurality of diffracted lights.   11. When inspecting the unevenness of the pattern of the sample, the pixel of the DMD to which the diffracted light of the higher intensity among the diffracted lights of the plurality of orders enters is turned off. Inspection method described in 1.   When inspecting the unevenness of the pattern of the sample, the DMD pixel to which the diffracted light of the order other than the diffracted light having the large intensity change due to the unevenness among the diffracted lights of the plurality of orders is turned off The inspection method according to claim 10 or 11, wherein the state is set.   The diffracted light of the plurality of orders received by the photodetector is set with a different weighting coefficient depending on the order so as to emphasize the feature of unevenness of the pattern of the sample. The inspection method according to item 1.   The inspection method according to claim 13, wherein the intensity change of the diffracted light is emphasized using a different weighting coefficient for each of the plurality of orders of diffracted light received by the photodetector.   The inspection method according to claim 9, wherein a position of a light receiving system including the DMD and the photodetector with respect to the sample is changed, and an order of diffracted light incident on the photodetector is changed.   16. When inspecting a defect of a pattern of a previous sample, a pixel irradiated with diffracted light from the sample pattern of the DMD is turned off. Inspection method described in 1.

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