WO2019188296A1 - Image generating method - Google Patents
Image generating method Download PDFInfo
- Publication number
- WO2019188296A1 WO2019188296A1 PCT/JP2019/010283 JP2019010283W WO2019188296A1 WO 2019188296 A1 WO2019188296 A1 WO 2019188296A1 JP 2019010283 W JP2019010283 W JP 2019010283W WO 2019188296 A1 WO2019188296 A1 WO 2019188296A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- image generation
- area
- image
- pattern
- sample stage
- Prior art date
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/20—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials
- G01N23/203—Measuring back scattering
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/2206—Combination of two or more measurements, at least one measurement being that of secondary emission, e.g. combination of secondary electron [SE] measurement and back-scattered electron [BSE] measurement
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
- G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/30—Determination of transform parameters for the alignment of images, i.e. image registration
- G06T7/33—Determination of transform parameters for the alignment of images, i.e. image registration using feature-based methods
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/70—Determining position or orientation of objects or cameras
Definitions
- the present invention relates to an image generation method applicable to a pattern inspection apparatus that performs pattern inspection using pattern design data.
- Optical pattern inspection equipment using a die-to-die comparison method is used for pattern inspection of wafers in the manufacturing process of semiconductor integrated circuits or pattern inspection of photomasks for pattern formation.
- This die-to-die comparison method is a method of detecting defects by comparing images obtained from the same position of a semiconductor device called a die to be inspected and the adjacent die.
- a method called die-to-database comparison is used for inspection of a photomask called a reticle in which no adjacent die exists.
- This method is a method in which the mask data is converted into an image to replace the image of the proximity die used in the die-to-die comparison method, and the same inspection as described above is performed.
- the mask data is data obtained by applying photomask correction to the design data.
- the corner round of the pattern actually formed on the wafer is detected as a defect.
- corner rounds are not detected as defects in the pre-processing in which a corner round is given to the image converted from the mask data with a smoothing filter.
- the corner round by this pre-processing is not equal to the corner round of each pattern formed on the wafer, so that the corner round may not be detected as a defect. Therefore, if the allowable pattern deformation amount is set so as to ignore this difference, there is a problem in that minute defects existing other than corners cannot be detected.
- Repeated defects are defined as defects that occur repeatedly in all dies on a wafer due to a photomask defect or the like. Repeated defects occur in both the die to be inspected and the adjacent die to be compared, and cannot be detected by die-to-die comparison. Therefore, there is a need for wafer inspection using a die-to-database comparison method.
- the position of the pattern is determined using the SEM image of the pattern and the pattern on the design data of the pattern. Has been identified. That is, by performing pattern matching between the SEM image and the pattern on the design data, the position of the pattern on the image can be specified.
- patterns of the same shape are repeatedly arranged in the field of view, it is difficult to associate individual patterns on the image with corresponding patterns on the design data. As a result, it is difficult to specify the position of the pattern on the image by pattern matching.
- this error is referred to as a movement error. Due to the existence of this movement error, it is difficult to accurately specify the position of the pattern on the image. In particular, it is difficult to specify the position of the pattern on the image with sub-nanometer order or nanometer order accuracy.
- the present invention provides an image generation method capable of accurately specifying the position of a pattern on an image.
- an image generation method using a scanning electron microscope wherein a characteristic pattern at the shortest distance from a preset inspection region is determined using design data of a pattern formed on a sample, Determining a reference position which is a position of the determined characteristic pattern, setting a plurality of image generation areas including at least the reference position and the inspection area so that two adjacent image generation areas overlap, and Each time the sample stage is sequentially moved to the plurality of image generation regions in the direction from the position toward the inspection region, and the sample stage is moved to any of the plurality of image generation regions, the image of the image generation region is changed. Generating and calculating a movement error of the sample stage using at least the image, and based on the movement error, a current position of the sample stage is calculated. Corrects the information, the image generating method for generating an image of the inspection area is provided.
- the plurality of image generation areas are a minimum number of image generation areas that can connect the reference position and the inspection area.
- the step of calculating the movement error of the sample stage includes a step of calculating a positional deviation between patterns appearing in both two images of two adjacent image generation regions.
- the step of calculating the movement error of the sample stage further includes a step of calculating a positional deviation between the characteristic pattern on the image and a corresponding pattern on the design data.
- the image of the image generation area includes an image of a first area in the image generation area and an image of a second area in the image generation area, and the second area is another adjacent image. It overlaps with the first region of the generation region.
- the position information of the inspection area on the image substantially matches the position information of the inspection area on the design data. To do. Therefore, the position of the pattern on the image can be specified with sub-nanometer order accuracy or nanometer order accuracy.
- FIG. 1 is a schematic diagram showing an embodiment of a pattern inspection apparatus provided with a scanning electron microscope.
- the pattern inspection apparatus includes a scanning electron microscope 100 and a computer 150 that controls the operation of the scanning electron microscope.
- the scanning electron microscope 100 includes an electron gun 111 that emits an electron beam composed of primary electrons (charged particles), a focusing lens 112 that focuses the electron beam emitted from the electron gun 111, and an X deflector that deflects the electron beam in the X direction. 113, a Y deflector 114 that deflects the electron beam in the Y direction, and an objective lens 115 that focuses the electron beam on a wafer 124 that is a sample.
- the focusing lens 112 and the objective lens 115 are connected to a lens control device 116, and the operations of the focusing lens 112 and the objective lens 115 are controlled by the lens control device 116.
- This lens control device 116 is connected to a computer 150.
- the X deflector 113 and the Y deflector 114 are connected to a deflection control device 117, and the deflection operations of the X deflector 113 and the Y deflector 114 are controlled by the deflection control device 117.
- This deflection control device 117 is also connected to the computer 150 in the same manner.
- the secondary electron detector 130 and the backscattered electron detector 131 are connected to the image acquisition device 118.
- the image acquisition device 118 is configured to convert the output signals of the secondary electron detector 130 and the backscattered electron detector 131 into an image. This image acquisition device 118 is similarly connected to the computer 150.
- the sample stage 121 arranged in the sample chamber 120 is connected to a stage control device 122, and the position of the sample stage 121 is controlled by the stage control device 122.
- This stage control device 122 is connected to a computer 150.
- a wafer transfer device 140 for placing the wafer 124 on the sample stage 121 in the sample chamber 120 is also connected to the computer 150.
- the computer 150 includes a storage device 162 in which a design database 161 is stored, an input device 163 such as a keyboard and a mouse, and a display device 164 having a screen for displaying images and a graphical user interface (GUI).
- GUI graphical user interface
- the electron beam emitted from the electron gun 111 is focused by the focusing lens 112, then focused by the objective lens 115 while being deflected by the X deflector 113 and the Y deflector 114, and irradiated onto the surface of the wafer 124.
- the wafer 124 is irradiated with primary electrons of an electron beam, secondary electrons and reflected electrons are emitted from the wafer 124. Secondary electrons are detected by the secondary electron detector 130, and reflected electrons are detected by the reflected electron detector 131.
- the detected secondary electron signal and reflected electron signal are input to the image acquisition device 118 and converted into image data.
- the image data is transmitted to the computer 150, and the image of the wafer 124 is displayed on the display device 164 of the computer 150.
- the design data of the wafer 124 (including design information such as pattern dimensions and pattern positions) is stored in the storage device 162 in advance.
- a design database 161 is constructed in the storage device 162.
- the design data of the wafer 124 is stored in advance in the design database 161.
- the computer 150 can read the design data of the wafer 124 from the design database 161 stored in the storage device 162.
- FIG. 2 is a schematic diagram showing an example of a repetitive pattern formed on the wafer 124.
- the repeating pattern 201 has substantially the same shape and is regularly arranged.
- the repetitive pattern 201 is a hole pattern.
- Reference numeral 200 represents a pattern area where the repeated pattern 201 is formed, and a space exists outside the pattern area 200.
- the inspection area 203 that is the target area is set in the pattern area 200. In one example, the inspection area 203 is set by the user operating the input device 163 shown in FIG.
- the inspection area 203 is located in the pattern area 200 and is smaller than the pattern area 200. Only the repeated pattern 201 exists in the inspection area 203, and there is no characteristic pattern that can identify the position of the repeated pattern 201 in the inspection area 203.
- the reference position for specifying the position of the repeated pattern in the inspection area 203 is determined as follows. First, the computer 150 searches for a characteristic pattern existing around the inspection area 203 by using the design data used to create the pattern on the wafer 124.
- the characteristic pattern includes not only a pattern having a characteristic shape but also a pattern having a characteristic position.
- An example of a pattern having a characteristic shape is a pattern having a shape different from the repeated pattern 201.
- An example of the pattern whose position is characteristic is a pattern that can specify the position.
- the four repeated patterns 201A, 201B, 201C, and 201D that form the four corners of the pattern region 200 are patterns whose positions are characteristic.
- FIG. 3 is a diagram illustrating distances d1, d2, d3, and d4 from the inspection region 203 to the characteristic patterns 201A, 201B, 201C, and 201D.
- the computer 150 determines the shortest distance among the calculated distances d1, d2, d3, and d4. As can be seen from FIG. 3, the distance d1 is the shortest distance.
- the computer 150 determines a characteristic pattern 201A that is at the shortest distance d1 from the inspection area 203. Further, the computer 150 determines a reference position 210 that is the position of the determined characteristic pattern 201A.
- FIG. 4 is a diagram showing a reference position 210 determined from the characteristic pattern 201A.
- FIG. 5 is a flowchart for determining the reference position 210.
- the computer 150 searches for characteristic patterns 201A, 201B, 201C, and 201D existing around the inspection region 203 using the design data (see FIG. 2).
- the computer 150 calculates distances from the inspection region 203 to the plurality of characteristic patterns 201A, 201B, 201C, and 201D using the design data (see FIG. 3).
- step 3 the computer 150 determines the shortest distance d1 among the calculated distances d1, d2, d3, d4.
- step 4 the computer 150 determines a characteristic pattern 201 ⁇ / b> A that is at the shortest distance d ⁇ b> 1 from the inspection area 203.
- step 5 the computer 150 determines a reference position 210 that is the position of the determined characteristic pattern 201A (see FIG. 4).
- the computer 150 sets a plurality of image generation areas 221, 222, 223, and 224 including at least the reference position 210 and the inspection area 203 so that two adjacent image generation areas overlap.
- Each image generation area corresponds to a field of view (FOV).
- the image generation area is a rectangular area defined by a dimension in the X direction and a dimension in the Y direction perpendicular to the X direction.
- the computer 150 can change the size (size) and position of the image generation areas 221, 222, 223, and 224.
- the sample stage 121 on which the wafer 124 is placed is sequentially moved to a plurality of image generation regions 221, 222, 223, and 224.
- the number of image generation regions is a minimum.
- at least one of the plurality of image generation areas to be set is the size of the maximum field of view of the scanning electron microscope 100 in the X or Y direction, or each image generation area It is preferable to have a dimension corresponding to the remaining distance in the X direction or the Y direction from the outer end of the inspection region 203 to the inspection region 203. In the example illustrated in FIG.
- the dimensions of the first image generation region 221 in the X direction and the Y direction correspond to the dimensions of the maximum field of view of the scanning electron microscope 100 in the X direction and the Y direction.
- the dimension in the X direction of the second image generation area 222 corresponds to the dimension in the X direction of the maximum field of view of the scanning electron microscope 100, and the dimension in the Y direction of the image generation area 222 is inspected from the outer edge of the image generation area 222. This is a dimension corresponding to the remaining distance in the Y direction up to the region 203.
- a region where two adjacent image generation regions overlap (hereinafter referred to as a superimposed region) is indicated by hatching. That is, the end of each image generation area overlaps the end of another adjacent image generation area.
- the size of each overlapping region is set as appropriate.
- the image generation areas 221, 222, 223, and 224 are connected in a line from the reference position 210 to the inspection area 203, with some of them overlapping.
- the set image generation areas 221, 222, 223, and 224 are the minimum number of image generation areas that can connect the reference position 210 and the inspection area 203. In the present embodiment, four image generation areas are set. However, if the image generation areas are connected from the reference position 210 to the inspection area 203, only two image generation areas may be set.
- the width of each of the plurality of image generation areas 221, 222, 223, and 224 is smaller than the distance between the reference position 210 and the inspection area 203.
- the image generation region 221 including the reference position 210 is referred to as a first image generation region
- the image generation region 224 including the inspection region 203 is referred to as a fourth image generation region
- the first image generation region 221 and the fourth image generation region 221 The image generation areas 222 and 223 located between the image generation area 224 and the image generation area 224 are referred to as a second image generation area and a third image generation area, respectively.
- the computer 150 issues a command to the stage control device 122 to sequentially move the sample stage 121 to the plurality of image generation regions 221, 222, 223, and 224.
- the direction in which the sample stage 121 is moved is a direction from the reference position 210 toward the inspection region 203.
- the sample stage 121 is moved in the order of the image generation areas 221, 222, 223, and 224.
- the movement of the sample stage 121 is defined as an operation in which the sample stage 121 moves the wafer (sample) in a direction toward the set target position.
- the computer 150 issues a command to the scanning electron microscope 100 to generate an image of the image generation region. Specifically, when the sample stage 121 moves to the first image generation region 221, the scanning electron microscope 100 generates an image of the first image generation region 221 on the wafer 124. Next, when the sample stage 121 moves to the second image generation area 222, the scanning electron microscope 100 generates an image of the second image generation area 222 of the wafer 124. Similarly, when the sample stage 121 moves to the next image generation area, the scanning electron microscope 100 generates an image of the image generation area. The scanning electron microscope 100 may generate an entire image of each image generation area. However, in order to reduce the image generation time, in the present embodiment, the first area and the second area in each image generation area. Only the image of is generated.
- FIG. 7 is a diagram showing the first region 221a and the second region 221b in the first image generation region 221.
- the first area 221 a is an area including the reference position 210
- the second area 221 b is an area overlapping with the second image generation area 222.
- the sample stage 121 moves from the initial position to the first image generation area 221.
- the target movement position of the sample stage 121 is a position on the design data corresponding to the reference position 210.
- the scanning electron microscope 100 generates an image of the first area 221 a and an image of the second area 221 b in the first image generation area 221 of the wafer 124.
- the computer 150 acquires the image of the first area 221a and the image of the second area 221b from the scanning electron microscope 100. Then, the computer 150 executes pattern matching between the pattern on the image of the first region 221a and the corresponding pattern on the design data. This pattern matching is alignment (alignment) between the pattern in the first image generation region 221 and the corresponding pattern on the design data.
- FIG. 8 is a schematic diagram showing a state in which pattern matching is executed between the pattern on the image of the first area 221a in the first image generation area 221 and the corresponding pattern on the design data. Since the first area 221a includes the reference position 210, a characteristic pattern 201A at the reference position 210 appears in the image of the first area 221a. Therefore, the computer 150 can align the repeated pattern 201 (including the characteristic pattern 201A) on the image of the first region 221a with the corresponding pattern 300 on the design data.
- the computer 150 causes the image (that is, the first image generation area 221) until the characteristic pattern 201 ⁇ / b> A and the other repeated pattern 201 match the corresponding pattern 300 on the design data.
- the image of the first area 221a and the image of the second area 221b in the image generation area 221 are moved.
- the moving distance and moving direction of the image in the first image generation area 221 at this time are the movement of the sample stage 121 that occurs when the sample stage 121 moves from the initial position to the first image generation area 221 (that is, the reference position 210). It corresponds to the error.
- the movement error of the sample stage 121 corresponds to a deviation of the position after the movement of the sample stage 121 from the movement target position.
- the movement error of the sample stage 121 corresponds to a positional deviation between the characteristic pattern 201A on the image and the corresponding pattern 300 on the design data. Therefore, the computer 150 can obtain the movement error of the sample stage 121 by calculating the positional deviation between the characteristic pattern 201A on the image and the corresponding pattern 300 on the design data.
- the computer 150 stores a movement error including the movement distance and the movement direction of the image in the first image generation area 221 in the storage device 162.
- the computer 150 corrects the current position information of the sample stage 121 based on the movement error of the sample stage 121. By correcting the position information, the position information of the sample stage 121 matches the position information on the design data.
- the computer 150 issues a command to the stage controller 122 to move the sample stage 121 from the first image generation area 221 to the second image generation area 222.
- the target movement position of the sample stage 121 is a position on the design data corresponding to the center of the second image generation region 222.
- FIG. 9 is a diagram showing the first region 222a and the second region 222b in the second image generation region 222.
- the first area 222a in the second image generation area 222 is an area that overlaps the second area 221b in the first image generation area 221, and the second area 222b in the second image generation area 222 is the third image generation. This is an area overlapping with the area 223.
- the computer 150 acquires the image of the first area 222 a and the image of the second area 222 b from the scanning electron microscope 100. Then, the computer 150 performs pattern matching between the pattern on the image of the second area 221b in the first image generation area 221 and the pattern on the image of the first area 222a in the second image generation area 222. To do.
- This pattern matching is alignment (alignment) between the pattern in the first image generation area 221 and the pattern in the second image generation area 222.
- FIG. 10 shows pattern matching between the pattern 201a on the image of the second area 221b in the first image generation area 221 and the pattern 201b on the image of the first area 222a in the second image generation area 222. It is a schematic diagram which shows a mode that is doing.
- the pattern 201 a on the image of the second region 221 b and the pattern 201 b on the image of the first region 222 a are the same pattern existing on the wafer 124. In other words, the same pattern appears in both of the two images in the two adjacent image generation regions 221 and 222.
- a pattern appearing in both of these two images is in an overlapping region of two adjacent image generation regions.
- the patterns 201a and 201b are created based on patterns having the same shape on the design data, but the shapes of the patterns 201a and 201b are slightly different as shown in FIG. Due to the difference in shape, the luminance profiles of the patterns 201a and 201b are also different.
- a luminance profile is a distribution of luminance along a line segment that traverses the pattern.
- the computer 150 can perform pattern matching between the pattern 201a and the pattern 201b based on the shape or luminance profile between patterns. As a result, the computer 150 can align the pattern 201b on the image in the first area 222a with the pattern 201a on the image in the second area 221b.
- the computer 150 determines that the image in the second image generation area 222 (that is, the second image generation area) until the pattern 201b on the image in the first area 222a matches the corresponding pattern 201a on the image in the second area 221b.
- the image of the first region 222a and the image of the second region 222b) in 222 are moved.
- the moving distance and moving direction of the image in the second image generation area 222 at this time are the movement errors of the sample stage 121 that occur when the sample stage 121 moves from the first image generation area 221 to the second image generation area 222. It corresponds to.
- the movement error of the sample stage 121 corresponds to a positional deviation between the pattern on the image in the first image generation area 221 and the pattern on the image in the second image generation area 222. Therefore, the computer 150 calculates the displacement between the pattern on the image of the first image generation area 221 and the pattern on the image of the second image generation area 222, thereby obtaining the movement error of the sample stage 121. be able to.
- the computer 150 stores a movement error including the movement distance and the movement direction of the image in the second image generation area 222 in the storage device 162.
- the computer 150 corrects the current position information of the sample stage 121 based on the movement error of the sample stage 121. By correcting the position information, the position information of the sample stage 121 matches the position information on the design data.
- the sample stage 121 is moved from the second image generation area 222 to the third image generation area 223.
- the movement target position of the sample stage 121 is a position on the design data corresponding to the center of the third image generation region 223.
- the scanning electron microscope 100 generates images of the first region 223a and the second region 223b in the third image generation region 223.
- the computer 150 acquires images of the first area 223 a and the second area 223 b from the scanning electron microscope 100. Then, the computer 150 performs pattern matching between the pattern on the image of the second area 222b in the second image generation area 222 and the pattern on the image of the first area 223a in the third image generation area 223. .
- the computer 150 calculates a movement error of the sample stage 121 that occurs when the sample stage 121 moves from the second image generation region 222 to the third image generation region 223, and obtains the current position information of the sample stage 121. The correction is made based on the movement error of the sample stage 121.
- the sample stage 121 is moved from the third image generation area 223 to the fourth image generation area 224.
- the movement target position of the sample stage 121 is a position on the design data corresponding to the center of the fourth image generation region 224.
- the scanning electron microscope 100 generates an image of the first region 224a in the fourth image generation region 224.
- the computer 150 acquires an image of the first region 224a from the scanning electron microscope 100. Then, the computer 150 performs pattern matching between the pattern on the image of the second area 223b in the third image generation area 222 and the pattern on the image of the first area 224a in the fourth image generation area 224. .
- the computer 150 calculates a movement error of the sample stage 121 that occurs when the sample stage 121 moves from the third image generation region 223 to the fourth image generation region 224, and obtains the current position information of the sample stage 121. The correction is made based on the movement error of the sample stage 121.
- the scanning electron microscope 100 generates an image of the inspection area 203, and the computer 150 acquires the image of the inspection area 203 from the scanning electron microscope 100.
- the computer 150 uses the image of the inspection area 203 to perform inspection such as pattern defect inspection or pattern measurement.
- the position information of the inspection area 203 on the image is substantially the same as the position information of the inspection area 203 on the design data.
- the computer 150 can calculate the position of each pattern in the inspection region 203 based on the corrected position information of the sample stage 121. According to this embodiment, it is possible to specify the position of each pattern in the inspection region 203 with sub-nanometer order or nanometer order accuracy. Furthermore, since the sample stage 121 moves along the shortest route from the reference position 210 to the inspection area 203, the pattern inspection in the inspection area 203 can be executed promptly.
- FIG. 13 and FIG. 14 are flowcharts for explaining the process of specifying the position of the repetitive pattern in the inspection area 203 based on the reference position 210.
- a plurality of image generation areas 221, 222, 223, and 224 including at least the reference position 210 and the inspection area (target area) 203 are set so that two adjacent image generation areas overlap (see FIG. 6).
- the sample stage 121 is moved to the first image generation region 221 (more specifically, the reference position 210).
- images of the first area 221a and the second area 221b in the first image generation area 221 are generated (see FIG. 7).
- step 4 pattern matching is executed between the pattern on the image of the first region 221a and the corresponding pattern on the design data.
- step 5 the current position information of the sample stage 121 is corrected based on the movement error of the sample stage 121 obtained from the pattern matching result.
- step 6 an initial value of 2 is set to “n” representing the number of the image generation area.
- step 7 it is determined whether “n” is a set upper limit. The setting upper limit corresponds to the number of the plurality of image generation areas set in step 1 above.
- step 8 the sample stage 121 is moved to the nth image generation region.
- step 9 images of the first area and the second area in the nth image generation area are generated.
- step 10 pattern matching is performed between the pattern on the image of the second area in the n ⁇ 1th image generation area and the pattern on the image of the first area in the nth image generation area.
- step 11 the current position information of the sample stage 121 is corrected based on the movement error of the sample stage 121 obtained from the pattern matching result.
- step 12 1 is added to n.
- step 7 if “n” is the upper limit, the sample stage 121 is moved to the nth image generation region in step 13.
- step 14 an image of the first area in the nth image generation area is generated.
- step 15 pattern matching is performed between the pattern on the image of the second area in the n ⁇ 1th image generation area and the pattern on the image of the first area in the nth image generation area.
- step 16 the current position information of the sample stage 121 is corrected based on the movement error of the sample stage 121 obtained from the pattern matching result.
- step 17 an image of the inspection area 203 is generated.
- step 18 inspection such as pattern defect inspection or pattern measurement is performed using the image of the inspection region 203.
- the present invention can be used in an image generation method applicable to a pattern inspection apparatus that performs pattern inspection using pattern design data.
Landscapes
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Immunology (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Pathology (AREA)
- Health & Medical Sciences (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Theoretical Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Image Analysis (AREA)
Abstract
In this image generating method: a reference position (210), which is a position (201A) of a characteristic pattern, is determined; a plurality of image generating regions (221, 222, 223, 224) including at least the reference position (210) and an inspection region (203) are set in such a way that two adjacent image generating regions overlap one another; a specimen stage (121) is moved sequentially to the plurality of image generating regions (221, 222, 223, 224); each time the specimen stage (121) is moved to any of the plurality of image generating regions (221, 222, 223, 224), an image of the image generating region is generated, and a movement error of the specimen stage (121) is calculated using at least the image; and current position information of the specimen stage (121) is adjusted on the basis of the movement error to generate an image of the inspection region (203).
Description
本発明は、パターンの設計データを用いてパターン検査を行うパターン検査装置に適用可能な画像生成方法に関する。
The present invention relates to an image generation method applicable to a pattern inspection apparatus that performs pattern inspection using pattern design data.
半導体集積回路の製造工程におけるウェーハのパターン検査、あるいはそのパターン形成用のホトマスクのパターン検査には、ダイ・ツー・ダイ(die to die)比較方法を用いた光学式パターン検査装置が使われている。このダイ・ツー・ダイ比較方法は、検査対象のダイと呼ばれる半導体デバイスとその近接ダイの同じ位置から得られる画像どうしを比較することで欠陥を検出する方法である。
Optical pattern inspection equipment using a die-to-die comparison method is used for pattern inspection of wafers in the manufacturing process of semiconductor integrated circuits or pattern inspection of photomasks for pattern formation. . This die-to-die comparison method is a method of detecting defects by comparing images obtained from the same position of a semiconductor device called a die to be inspected and the adjacent die.
一方、近接ダイの存在しないレチクルと呼ばれるホトマスクの検査には、ダイ・ツー・データベース(die to database)比較と呼ばれる方法が使用されている。この方法は、マスクデータを画像に変換してダイ・ツー・ダイ比較方法で用いた近接ダイの画像の代わりとし、前述同様の検査をする方法である。マスクデータとは設計データにホトマスク用の補正を施して得られるデータである。
On the other hand, a method called die-to-database comparison is used for inspection of a photomask called a reticle in which no adjacent die exists. This method is a method in which the mask data is converted into an image to replace the image of the proximity die used in the die-to-die comparison method, and the same inspection as described above is performed. The mask data is data obtained by applying photomask correction to the design data.
しかし、ダイ・ツー・データベース比較方法をウェーハ検査に使用すると、実際にウェーハに形成されたパターンのコーナーラウンドが欠陥として検出される。ホトマスクの検査では、マスクデータから変換された画像にスムージングフィルタでコーナーラウンドをもたせる前処理でコーナーラウンドを欠陥として検出しないようにしている。しかしながら、ウェーハ検査では、この前処理によるコーナーラウンドは、ウェーハに形成されたそれぞれのパターンのコーナーラウンドに等しくないので、コーナーラウンドを欠陥として検出しないようにできないことがある。そこで、この違いを無視するように許容パターン変形量を設定すると、コーナー以外に存在する微小欠陥を検出できないという問題が発生している。
However, when the die-to-database comparison method is used for wafer inspection, the corner round of the pattern actually formed on the wafer is detected as a defect. In the inspection of the photomask, corner rounds are not detected as defects in the pre-processing in which a corner round is given to the image converted from the mask data with a smoothing filter. However, in the wafer inspection, the corner round by this pre-processing is not equal to the corner round of each pattern formed on the wafer, so that the corner round may not be detected as a defect. Therefore, if the allowable pattern deformation amount is set so as to ignore this difference, there is a problem in that minute defects existing other than corners cannot be detected.
半導体集積回路生産での問題に注目すると、ゴミなどに起因するランダム欠陥よりも繰り返し発生する欠陥が重要視されている。繰り返し発生する欠陥(システマティック欠陥)とは、ホトマスク不良などを原因としてウェーハ上の全ダイにおいて繰り返し発生する欠陥と定義される。繰り返し発生する欠陥は検査対象のダイおよびその比較対象の近接ダイの両方に発生しているため、ダイ・ツー・ダイ比較では検出できない。ゆえに、ダイ・ツー・データベース比較方式でのウェーハ検査が必要とされている。
Focusing on problems in semiconductor integrated circuit production, defects that occur repeatedly rather than random defects caused by dust are regarded as important. Repeated defects (systematic defects) are defined as defects that occur repeatedly in all dies on a wafer due to a photomask defect or the like. Repeated defects occur in both the die to be inspected and the adjacent die to be compared, and cannot be detected by die-to-die comparison. Therefore, there is a need for wafer inspection using a die-to-database comparison method.
システマティック欠陥を対象としたダイ・ツー・データベース比較方式では、ウェーハ上の欠陥検出やパターン検査をする場合、パターンのSEM画像と、そのパターンの設計データ上のパターンとを用いて、そのパターンの位置を特定している。すなわち、SEM画像と設計データ上のパターンとの間でパターンマッチングを実行することにより、画像上のパターンの位置が特定できる。しかしながら、同じ形状のパターンが視野内に繰り返し配列されている場合、画像上の個別のパターンを、設計データ上の対応するパターンに関連付けることは困難である。結果として、パターンマッチングでは画像上のパターンの位置を特定することは困難である。
In the die-to-database comparison method for systematic defects, when performing defect detection or pattern inspection on a wafer, the position of the pattern is determined using the SEM image of the pattern and the pattern on the design data of the pattern. Has been identified. That is, by performing pattern matching between the SEM image and the pattern on the design data, the position of the pattern on the image can be specified. However, when patterns of the same shape are repeatedly arranged in the field of view, it is difficult to associate individual patterns on the image with corresponding patterns on the design data. As a result, it is difficult to specify the position of the pattern on the image by pattern matching.
加えて、ウェーハを載せた試料ステージを目標位置に移動させたとき、目標位置と試料ステージの実際の位置との間にはある程度の誤差がある(以下、この誤差を移動誤差という)。この移動誤差の存在のために、画像上のパターンの位置を正確に特定することは難しい。特に、画像上のパターンの位置を、サブナノメートルオーダーまたはナノメートルオーダーの精度で特定することは困難である。
In addition, when the sample stage on which the wafer is placed is moved to the target position, there is a certain amount of error between the target position and the actual position of the sample stage (hereinafter, this error is referred to as a movement error). Due to the existence of this movement error, it is difficult to accurately specify the position of the pattern on the image. In particular, it is difficult to specify the position of the pattern on the image with sub-nanometer order or nanometer order accuracy.
そこで、本発明は、画像上のパターンの位置を正確に特定することができる画像生成方法を提供する。
Therefore, the present invention provides an image generation method capable of accurately specifying the position of a pattern on an image.
一態様では、走査電子顕微鏡を用いた画像生成方法であって、試料に形成されたパターンの設計データを用いて予め設定された検査領域から最も短い距離にある特徴的なパターンを決定し、前記決定された特徴的なパターンの位置である基準位置を決定し、前記基準位置および前記検査領域を少なくとも含む複数の画像生成領域を、隣接する2つの画像生成領域が重なり合うように設定し、前記基準位置から前記検査領域に向かう方向に、試料ステージを前記複数の画像生成領域に順次移動させ、前記試料ステージを前記複数の画像生成領域のいずれかに移動させるたびに、その画像生成領域の画像を生成し、かつ少なくとも前記画像を用いて前記試料ステージの移動誤差を算出し、前記移動誤差に基づいて、前記試料ステージの現在の位置情報を補正し、前記検査領域の画像を生成する画像生成方法が提供される。
In one aspect, an image generation method using a scanning electron microscope, wherein a characteristic pattern at the shortest distance from a preset inspection region is determined using design data of a pattern formed on a sample, Determining a reference position which is a position of the determined characteristic pattern, setting a plurality of image generation areas including at least the reference position and the inspection area so that two adjacent image generation areas overlap, and Each time the sample stage is sequentially moved to the plurality of image generation regions in the direction from the position toward the inspection region, and the sample stage is moved to any of the plurality of image generation regions, the image of the image generation region is changed. Generating and calculating a movement error of the sample stage using at least the image, and based on the movement error, a current position of the sample stage is calculated. Corrects the information, the image generating method for generating an image of the inspection area is provided.
一態様では、前記複数の画像生成領域は、前記基準位置と前記検査領域とをつなぐことができる最小の数の複数の画像生成領域である。
一態様では、前記試料ステージの移動誤差を算出する工程は、隣接する2つの画像生成領域の2つの画像の両方に現れるパターン間の位置ずれを算出する工程を含む。
一態様では、前記試料ステージの移動誤差を算出する工程は、画像上の前記特徴的なパターンと、設計データ上の対応するパターンとの位置ずれを算出する工程をさらに含む。
一態様では、前記画像生成領域の画像は、前記画像生成領域内の第1領域の画像と、前記画像生成領域内の第2領域の画像を含み、前記第2領域は、隣接する他の画像生成領域の第1領域と重なり合っている。 In one aspect, the plurality of image generation areas are a minimum number of image generation areas that can connect the reference position and the inspection area.
In one aspect, the step of calculating the movement error of the sample stage includes a step of calculating a positional deviation between patterns appearing in both two images of two adjacent image generation regions.
In one aspect, the step of calculating the movement error of the sample stage further includes a step of calculating a positional deviation between the characteristic pattern on the image and a corresponding pattern on the design data.
In one aspect, the image of the image generation area includes an image of a first area in the image generation area and an image of a second area in the image generation area, and the second area is another adjacent image. It overlaps with the first region of the generation region.
一態様では、前記試料ステージの移動誤差を算出する工程は、隣接する2つの画像生成領域の2つの画像の両方に現れるパターン間の位置ずれを算出する工程を含む。
一態様では、前記試料ステージの移動誤差を算出する工程は、画像上の前記特徴的なパターンと、設計データ上の対応するパターンとの位置ずれを算出する工程をさらに含む。
一態様では、前記画像生成領域の画像は、前記画像生成領域内の第1領域の画像と、前記画像生成領域内の第2領域の画像を含み、前記第2領域は、隣接する他の画像生成領域の第1領域と重なり合っている。 In one aspect, the plurality of image generation areas are a minimum number of image generation areas that can connect the reference position and the inspection area.
In one aspect, the step of calculating the movement error of the sample stage includes a step of calculating a positional deviation between patterns appearing in both two images of two adjacent image generation regions.
In one aspect, the step of calculating the movement error of the sample stage further includes a step of calculating a positional deviation between the characteristic pattern on the image and a corresponding pattern on the design data.
In one aspect, the image of the image generation area includes an image of a first area in the image generation area and an image of a second area in the image generation area, and the second area is another adjacent image. It overlaps with the first region of the generation region.
上記態様によれば、試料ステージが移動するたびに試料ステージの現在の位置情報が補正されるので、画像上の検査領域の位置情報は、設計データ上の検査領域の位置情報に実質的に一致する。したがって、画像上のパターンの位置をサブナノメートルオーダーまたはナノメートルオーダーの精度で特定することができる。
According to the above aspect, since the current position information of the sample stage is corrected each time the sample stage moves, the position information of the inspection area on the image substantially matches the position information of the inspection area on the design data. To do. Therefore, the position of the pattern on the image can be specified with sub-nanometer order accuracy or nanometer order accuracy.
以下、本発明の実施形態について図面を参照して説明する。
図1は、走査電子顕微鏡を備えたパターン検査装置の一実施形態を示す模式図である。図1に示すように、パターン検査装置は、走査電子顕微鏡100と、走査電子顕微鏡の動作を制御するコンピュータ150とを備えている。走査電子顕微鏡100は、一次電子(荷電粒子)からなる電子ビームを発する電子銃111と、電子銃111から放出された電子ビームを集束する集束レンズ112、電子ビームをX方向に偏向するX偏向器113、電子ビームをY方向に偏向するY偏向器114、電子ビームを試料であるウェーハ124にフォーカスさせる対物レンズ115を有する。 Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing an embodiment of a pattern inspection apparatus provided with a scanning electron microscope. As shown in FIG. 1, the pattern inspection apparatus includes ascanning electron microscope 100 and a computer 150 that controls the operation of the scanning electron microscope. The scanning electron microscope 100 includes an electron gun 111 that emits an electron beam composed of primary electrons (charged particles), a focusing lens 112 that focuses the electron beam emitted from the electron gun 111, and an X deflector that deflects the electron beam in the X direction. 113, a Y deflector 114 that deflects the electron beam in the Y direction, and an objective lens 115 that focuses the electron beam on a wafer 124 that is a sample.
図1は、走査電子顕微鏡を備えたパターン検査装置の一実施形態を示す模式図である。図1に示すように、パターン検査装置は、走査電子顕微鏡100と、走査電子顕微鏡の動作を制御するコンピュータ150とを備えている。走査電子顕微鏡100は、一次電子(荷電粒子)からなる電子ビームを発する電子銃111と、電子銃111から放出された電子ビームを集束する集束レンズ112、電子ビームをX方向に偏向するX偏向器113、電子ビームをY方向に偏向するY偏向器114、電子ビームを試料であるウェーハ124にフォーカスさせる対物レンズ115を有する。 Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing an embodiment of a pattern inspection apparatus provided with a scanning electron microscope. As shown in FIG. 1, the pattern inspection apparatus includes a
集束レンズ112および対物レンズ115はレンズ制御装置116に接続され、集束レンズ112および対物レンズ115の動作はレンズ制御装置116によって制御される。このレンズ制御装置116はコンピュータ150に接続されている。X偏向器113、Y偏向器114は、偏向制御装置117に接続されており、X偏向器113、Y偏向器114の偏向動作は偏向制御装置117によって制御される。この偏向制御装置117も同様にコンピュータ150に接続されている。二次電子検出器130と反射電子検出器131は画像取得装置118に接続されている。画像取得装置118は二次電子検出器130と反射電子検出器131の出力信号を画像に変換するように構成される。この画像取得装置118も同様にコンピュータ150に接続されている。
The focusing lens 112 and the objective lens 115 are connected to a lens control device 116, and the operations of the focusing lens 112 and the objective lens 115 are controlled by the lens control device 116. This lens control device 116 is connected to a computer 150. The X deflector 113 and the Y deflector 114 are connected to a deflection control device 117, and the deflection operations of the X deflector 113 and the Y deflector 114 are controlled by the deflection control device 117. This deflection control device 117 is also connected to the computer 150 in the same manner. The secondary electron detector 130 and the backscattered electron detector 131 are connected to the image acquisition device 118. The image acquisition device 118 is configured to convert the output signals of the secondary electron detector 130 and the backscattered electron detector 131 into an image. This image acquisition device 118 is similarly connected to the computer 150.
試料チャンバー120内に配置される試料ステージ121は、ステージ制御装置122に接続されており、試料ステージ121の位置はステージ制御装置122によって制御される。このステージ制御装置122はコンピュータ150に接続されている。
The sample stage 121 arranged in the sample chamber 120 is connected to a stage control device 122, and the position of the sample stage 121 is controlled by the stage control device 122. This stage control device 122 is connected to a computer 150.
ウェーハ124を、試料チャンバー120内の試料ステージ121に載置するためのウェーハ搬送装置140も同様にコンピュータ150に接続されている。コンピュータ150は、設計データベース161が格納された記憶装置162、およびキーボード、マウス等の入力装置163、画像やグラフィカルユーザーインターフェイス(GUI)を表示する画面を備えた表示装置164を備えている。
A wafer transfer device 140 for placing the wafer 124 on the sample stage 121 in the sample chamber 120 is also connected to the computer 150. The computer 150 includes a storage device 162 in which a design database 161 is stored, an input device 163 such as a keyboard and a mouse, and a display device 164 having a screen for displaying images and a graphical user interface (GUI).
電子銃111から放出された電子ビームは集束レンズ112で集束された後に、X偏向器113、Y偏向器114で偏向されつつ対物レンズ115により集束されてウェーハ124の表面に照射される。ウェーハ124に電子ビームの一次電子が照射されると、ウェーハ124からは二次電子および反射電子が放出される。二次電子は二次電子検出器130により検出され、反射電子は反射電子検出器131により検出される。検出された二次電子の信号、および反射電子の信号は、画像取得装置118に入力され画像データに変換される。画像データはコンピュータ150に送信され、ウェーハ124の画像はコンピュータ150の表示装置164上に表示される。
The electron beam emitted from the electron gun 111 is focused by the focusing lens 112, then focused by the objective lens 115 while being deflected by the X deflector 113 and the Y deflector 114, and irradiated onto the surface of the wafer 124. When the wafer 124 is irradiated with primary electrons of an electron beam, secondary electrons and reflected electrons are emitted from the wafer 124. Secondary electrons are detected by the secondary electron detector 130, and reflected electrons are detected by the reflected electron detector 131. The detected secondary electron signal and reflected electron signal are input to the image acquisition device 118 and converted into image data. The image data is transmitted to the computer 150, and the image of the wafer 124 is displayed on the display device 164 of the computer 150.
ウェーハ124の設計データ(パターンの寸法、パターンの位置などの設計情報などを含む)は、記憶装置162に予め記憶されている。記憶装置162には、設計データベース161が構築されている。ウェーハ124の設計データは、設計データベース161内に予め格納される。コンピュータ150は、記憶装置162に格納されている設計データベース161からウェーハ124の設計データを読み出すことが可能である。
The design data of the wafer 124 (including design information such as pattern dimensions and pattern positions) is stored in the storage device 162 in advance. A design database 161 is constructed in the storage device 162. The design data of the wafer 124 is stored in advance in the design database 161. The computer 150 can read the design data of the wafer 124 from the design database 161 stored in the storage device 162.
図2は、ウェーハ124上に形成されている繰り返しパターンの一例を示す模式図である。繰り返しパターン201は、実質的に同じ形状を有し、かつ規則的に配列されている。図2に示す例では、繰り返しパターン201はホールパターンである。符号200は、繰り返しパターン201が形成されているパターン領域を表しており、このパターン領域200の外側にはスペースが存在している。目標領域である検査領域203は、パターン領域200内に設定される。一例では、ユーザーが図1に示す入力装置163を操作することによって検査領域203を設定する。検査領域203は、パターン領域200内に位置しており、かつパターン領域200に比べて小さい。検査領域203内には繰り返しパターン201のみが存在し、検査領域203内の繰り返しパターン201の位置を特定できるような特徴的なパターンは存在しない。
FIG. 2 is a schematic diagram showing an example of a repetitive pattern formed on the wafer 124. The repeating pattern 201 has substantially the same shape and is regularly arranged. In the example shown in FIG. 2, the repetitive pattern 201 is a hole pattern. Reference numeral 200 represents a pattern area where the repeated pattern 201 is formed, and a space exists outside the pattern area 200. The inspection area 203 that is the target area is set in the pattern area 200. In one example, the inspection area 203 is set by the user operating the input device 163 shown in FIG. The inspection area 203 is located in the pattern area 200 and is smaller than the pattern area 200. Only the repeated pattern 201 exists in the inspection area 203, and there is no characteristic pattern that can identify the position of the repeated pattern 201 in the inspection area 203.
本実施形態では、検査領域203内の繰り返しパターンの位置を特定するための基準位置を、次のようにして決定する。まず、コンピュータ150は、検査領域203の周辺に存在する特徴的なパターンを、ウェーハ124上のパターンの作成に用いられた設計データを用いて探索する。特徴的なパターンには、パターンの形状が特徴的であるもののみならず、パターンの位置が特徴的であるものも含まれる。形状が特徴的であるパターンの一例は、繰り返しパターン201とは異なる形状を持つパターンである。位置が特徴的であるパターンの一例は、位置を特定することができるパターンである。図2に示す例では、パターン領域200の4つの角を構成する4つの繰り返しパターン201A,201B,201C,201Dは、位置が特徴的なパターンである。
In this embodiment, the reference position for specifying the position of the repeated pattern in the inspection area 203 is determined as follows. First, the computer 150 searches for a characteristic pattern existing around the inspection area 203 by using the design data used to create the pattern on the wafer 124. The characteristic pattern includes not only a pattern having a characteristic shape but also a pattern having a characteristic position. An example of a pattern having a characteristic shape is a pattern having a shape different from the repeated pattern 201. An example of the pattern whose position is characteristic is a pattern that can specify the position. In the example illustrated in FIG. 2, the four repeated patterns 201A, 201B, 201C, and 201D that form the four corners of the pattern region 200 are patterns whose positions are characteristic.
次に、コンピュータ150は、繰り返しパターン201の設計データを用いて、検査領域203から複数の特徴的なパターン201A,201B,201C,201Dまでの距離を算出する。図3は、検査領域203から特徴的なパターン201A,201B,201C,201Dまでの距離d1,d2,d3,d4を示す図である。
Next, the computer 150 calculates the distances from the inspection region 203 to the plurality of characteristic patterns 201A, 201B, 201C, and 201D using the design data of the repeated pattern 201. FIG. 3 is a diagram illustrating distances d1, d2, d3, and d4 from the inspection region 203 to the characteristic patterns 201A, 201B, 201C, and 201D.
コンピュータ150は、算出された距離d1,d2,d3,d4のうち、最も短い距離を決定する。図3から分かるように、距離d1が最も短い距離である。コンピュータ150は、検査領域203から最も短い距離d1にある特徴的なパターン201Aを決定する。さらに、コンピュータ150は、決定された特徴的なパターン201Aの位置である基準位置210を決定する。図4は、特徴的なパターン201Aから定められた基準位置210を示す図である。
The computer 150 determines the shortest distance among the calculated distances d1, d2, d3, and d4. As can be seen from FIG. 3, the distance d1 is the shortest distance. The computer 150 determines a characteristic pattern 201A that is at the shortest distance d1 from the inspection area 203. Further, the computer 150 determines a reference position 210 that is the position of the determined characteristic pattern 201A. FIG. 4 is a diagram showing a reference position 210 determined from the characteristic pattern 201A.
図5は、上記基準位置210を決定するためのフローチャートである。ステップ1では、コンピュータ150は、設計データを用いて、検査領域203の周辺に存在する特徴的なパターン201A,201B,201C,201Dを探索する(図2参照)。ステップ2では、コンピュータ150は、設計データを用いて、検査領域203から複数の特徴的なパターン201A,201B,201C,201Dまでの距離を算出する(図3参照)。
FIG. 5 is a flowchart for determining the reference position 210. In step 1, the computer 150 searches for characteristic patterns 201A, 201B, 201C, and 201D existing around the inspection region 203 using the design data (see FIG. 2). In step 2, the computer 150 calculates distances from the inspection region 203 to the plurality of characteristic patterns 201A, 201B, 201C, and 201D using the design data (see FIG. 3).
ステップ3では、コンピュータ150は、算出された距離d1,d2,d3,d4のうち、最も短い距離d1を決定する。ステップ4では、コンピュータ150は、検査領域203から最も短い距離d1にある特徴的なパターン201Aを決定する。ステップ5では、コンピュータ150は、決定された特徴的なパターン201Aの位置である基準位置210を決定する(図4参照)。
In step 3, the computer 150 determines the shortest distance d1 among the calculated distances d1, d2, d3, d4. In step 4, the computer 150 determines a characteristic pattern 201 </ b> A that is at the shortest distance d <b> 1 from the inspection area 203. In step 5, the computer 150 determines a reference position 210 that is the position of the determined characteristic pattern 201A (see FIG. 4).
次に、検査領域203内の繰り返しパターンの位置を基準位置210に基づいて特定する工程について説明する。図6に示すように、コンピュータ150は、基準位置210および検査領域203を少なくとも含む複数の画像生成領域221,222,223,224を、隣接する2つの画像生成領域が重なり合うように設定する。各画像生成領域は、視野(Field of viewまたはFOV)に相当する。画像生成領域は、X方向の寸法と、X方向に垂直なY方向の寸法から定義される矩形状の領域である。コンピュータ150は、画像生成領域221,222,223,224の大きさ(寸法)および位置を変えることができる。
Next, a process of specifying the position of the repetitive pattern in the inspection area 203 based on the reference position 210 will be described. As illustrated in FIG. 6, the computer 150 sets a plurality of image generation areas 221, 222, 223, and 224 including at least the reference position 210 and the inspection area 203 so that two adjacent image generation areas overlap. Each image generation area corresponds to a field of view (FOV). The image generation area is a rectangular area defined by a dimension in the X direction and a dimension in the Y direction perpendicular to the X direction. The computer 150 can change the size (size) and position of the image generation areas 221, 222, 223, and 224.
後述するように、ウェーハ124を載せた試料ステージ121は、複数の画像生成領域221,222,223,224に順次移動される。試料ステージ121の移動回数を少なくするために、画像生成領域の数は最小であることが好ましい。最小の数の画像生成領域を達成するために、設定される複数の画像生成領域のうちの少なくとも1つは、走査電子顕微鏡100の最大視野のX方向またはY方向の寸法、または各画像生成領域の外端から検査領域203までのX方向またはY方向の残距離に相当する寸法を有することが好ましい。図6に示す例では、一番目の画像生成領域221のX方向およびY方向の寸法は、走査電子顕微鏡100の最大視野のX方向およびY方向の寸法に相当する。二番目の画像生成領域222のX方向の寸法は、走査電子顕微鏡100の最大視野のX方向の寸法に相当し、画像生成領域222のY方向の寸法は、画像生成領域222の外端から検査領域203までのY方向の残距離に相当する寸法である。このように各画像生成領域の大きさを最適化することで、試料ステージ121は基準位置210から検査領域203まで最短の時間で移動することができる。
As will be described later, the sample stage 121 on which the wafer 124 is placed is sequentially moved to a plurality of image generation regions 221, 222, 223, and 224. In order to reduce the number of movements of the sample stage 121, it is preferable that the number of image generation regions is a minimum. In order to achieve the minimum number of image generation areas, at least one of the plurality of image generation areas to be set is the size of the maximum field of view of the scanning electron microscope 100 in the X or Y direction, or each image generation area It is preferable to have a dimension corresponding to the remaining distance in the X direction or the Y direction from the outer end of the inspection region 203 to the inspection region 203. In the example illustrated in FIG. 6, the dimensions of the first image generation region 221 in the X direction and the Y direction correspond to the dimensions of the maximum field of view of the scanning electron microscope 100 in the X direction and the Y direction. The dimension in the X direction of the second image generation area 222 corresponds to the dimension in the X direction of the maximum field of view of the scanning electron microscope 100, and the dimension in the Y direction of the image generation area 222 is inspected from the outer edge of the image generation area 222. This is a dimension corresponding to the remaining distance in the Y direction up to the region 203. Thus, by optimizing the size of each image generation region, the sample stage 121 can move from the reference position 210 to the inspection region 203 in the shortest time.
図6において、隣接する2つの画像生成領域が重なり合う領域(以下、重畳領域という)は、ハッチングで示されている。すなわち、各画像生成領域の端部は、隣接する他の画像生成領域の端部と重なっている。各重畳領域の大きさは、適宜設定される。画像生成領域221,222,223,224は、その一部が重なり合いながら、基準位置210から検査領域203まで一列につながっている。設定される画像生成領域221,222,223,224は、基準位置210と検査領域203とをつなぐことができる最小の数の複数の画像生成領域である。本実施形態では、4つの画像生成領域が設定されているが、基準位置210から検査領域203まで画像生成領域がつながっていれば、2つの画像生成領域のみが設定されてもよい。複数の画像生成領域221,222,223,224のそれぞれの幅は、基準位置210と検査領域203との距離よりも小さい。
In FIG. 6, a region where two adjacent image generation regions overlap (hereinafter referred to as a superimposed region) is indicated by hatching. That is, the end of each image generation area overlaps the end of another adjacent image generation area. The size of each overlapping region is set as appropriate. The image generation areas 221, 222, 223, and 224 are connected in a line from the reference position 210 to the inspection area 203, with some of them overlapping. The set image generation areas 221, 222, 223, and 224 are the minimum number of image generation areas that can connect the reference position 210 and the inspection area 203. In the present embodiment, four image generation areas are set. However, if the image generation areas are connected from the reference position 210 to the inspection area 203, only two image generation areas may be set. The width of each of the plurality of image generation areas 221, 222, 223, and 224 is smaller than the distance between the reference position 210 and the inspection area 203.
以下の説明では、基準位置210を含む画像生成領域221を第1画像生成領域と称し、検査領域203を含む画像生成領域224を第4画像生成領域と称し、第1画像生成領域221と第4画像生成領域224との間に位置する画像生成領域222,223を、それぞれ第2画像生成領域および第3画像生成領域と称する。
In the following description, the image generation region 221 including the reference position 210 is referred to as a first image generation region, the image generation region 224 including the inspection region 203 is referred to as a fourth image generation region, and the first image generation region 221 and the fourth image generation region 221 The image generation areas 222 and 223 located between the image generation area 224 and the image generation area 224 are referred to as a second image generation area and a third image generation area, respectively.
コンピュータ150は、ステージ制御装置122に指令を発して試料ステージ121を複数の画像生成領域221,222,223,224に順次移動させる。試料ステージ121を移動させる方向は、基準位置210から検査領域203に向かう方向である。図6に示す例では、試料ステージ121は、画像生成領域221,222,223,224の順に移動される。本明細書では、試料ステージ121の移動は、試料ステージ121がウェーハ(試料)を、設定された目標位置に向かう方向に移動させる動作として定義される。
The computer 150 issues a command to the stage control device 122 to sequentially move the sample stage 121 to the plurality of image generation regions 221, 222, 223, and 224. The direction in which the sample stage 121 is moved is a direction from the reference position 210 toward the inspection region 203. In the example shown in FIG. 6, the sample stage 121 is moved in the order of the image generation areas 221, 222, 223, and 224. In this specification, the movement of the sample stage 121 is defined as an operation in which the sample stage 121 moves the wafer (sample) in a direction toward the set target position.
コンピュータ150は、試料ステージ121が各画像生成領域に移動するたびに、走査電子顕微鏡100に指令を発し、その画像生成領域の画像を生成させる。具体的には、試料ステージ121が第1画像生成領域221に移動すると、走査電子顕微鏡100は、ウェーハ124の第1画像生成領域221の画像を生成する。次に、試料ステージ121が第2画像生成領域222に移動すると、走査電子顕微鏡100は、ウェーハ124の第2画像生成領域222の画像を生成する。同様に、試料ステージ121が次の画像生成領域に移動すると、走査電子顕微鏡100は、その画像生成領域の画像を生成する。走査電子顕微鏡100は、各画像生成領域の全体の画像を生成してもよいが、画像の生成時間を短縮するために、本実施形態では、各画像生成領域内の第1領域と第2領域の画像のみを生成する。
Each time the sample stage 121 moves to each image generation region, the computer 150 issues a command to the scanning electron microscope 100 to generate an image of the image generation region. Specifically, when the sample stage 121 moves to the first image generation region 221, the scanning electron microscope 100 generates an image of the first image generation region 221 on the wafer 124. Next, when the sample stage 121 moves to the second image generation area 222, the scanning electron microscope 100 generates an image of the second image generation area 222 of the wafer 124. Similarly, when the sample stage 121 moves to the next image generation area, the scanning electron microscope 100 generates an image of the image generation area. The scanning electron microscope 100 may generate an entire image of each image generation area. However, in order to reduce the image generation time, in the present embodiment, the first area and the second area in each image generation area. Only the image of is generated.
図7は、第1画像生成領域221内の第1領域221aと第2領域221bを示す図である。第1領域221aは、基準位置210を含む領域であり、第2領域221bは、第2画像生成領域222と重なり合う領域である。最初に、試料ステージ121は、初期位置から第1画像生成領域221に移動する。試料ステージ121の移動目標位置は、基準位置210に対応する設計データ上の位置である。試料ステージ121が第1画像生成領域221に移動すると、走査電子顕微鏡100は、ウェーハ124の第1画像生成領域221内の第1領域221aの画像と第2領域221bの画像を生成する。
FIG. 7 is a diagram showing the first region 221a and the second region 221b in the first image generation region 221. As shown in FIG. The first area 221 a is an area including the reference position 210, and the second area 221 b is an area overlapping with the second image generation area 222. First, the sample stage 121 moves from the initial position to the first image generation area 221. The target movement position of the sample stage 121 is a position on the design data corresponding to the reference position 210. When the sample stage 121 moves to the first image generation area 221, the scanning electron microscope 100 generates an image of the first area 221 a and an image of the second area 221 b in the first image generation area 221 of the wafer 124.
コンピュータ150は、第1領域221aの画像と第2領域221bの画像を走査電子顕微鏡100から取得する。そして、コンピュータ150は、第1領域221aの画像上のパターンと、設計データ上の対応するパターンとの間でパターンマッチングを実行する。このパターンマッチングは、第1画像生成領域221内のパターンと、設計データ上の対応するパターンとの間の位置合わせ(アライメント)である。
The computer 150 acquires the image of the first area 221a and the image of the second area 221b from the scanning electron microscope 100. Then, the computer 150 executes pattern matching between the pattern on the image of the first region 221a and the corresponding pattern on the design data. This pattern matching is alignment (alignment) between the pattern in the first image generation region 221 and the corresponding pattern on the design data.
図8は、第1画像生成領域221内の第1領域221aの画像上のパターンと、設計データ上の対応するパターンとの間でパターンマッチングを実行している様子を示す模式図である。第1領域221aは基準位置210を含むので、第1領域221aの画像には、基準位置210にある特徴的なパターン201Aが現れる。したがって、コンピュータ150は、第1領域221aの画像上の繰り返しパターン201(特徴的なパターン201Aを含む)を、設計データ上の対応するパターン300にそれぞれ位置合わせすることができる。
FIG. 8 is a schematic diagram showing a state in which pattern matching is executed between the pattern on the image of the first area 221a in the first image generation area 221 and the corresponding pattern on the design data. Since the first area 221a includes the reference position 210, a characteristic pattern 201A at the reference position 210 appears in the image of the first area 221a. Therefore, the computer 150 can align the repeated pattern 201 (including the characteristic pattern 201A) on the image of the first region 221a with the corresponding pattern 300 on the design data.
図8に示すように、コンピュータ150は、特徴的なパターン201Aおよび他の繰り返しパターン201が、設計データ上の対応するパターン300に一致するまで、第1画像生成領域221の画像(すなわち、第1画像生成領域221内の第1領域221aの画像と第2領域221bの画像)を移動させる。このときの第1画像生成領域221の画像の移動距離および移動方向は、試料ステージ121が初期位置から第1画像生成領域221(すなわち基準位置210)まで移動するときに生じた試料ステージ121の移動誤差に相当する。試料ステージ121の移動誤差は、試料ステージ121の移動後の位置の、移動目標位置からの偏差に相当する。より具体的には、試料ステージ121の移動誤差は、画像上の特徴的なパターン201Aと、設計データ上の対応するパターン300との間の位置ずれに相当する。したがって、コンピュータ150は、画像上の特徴的なパターン201Aと、設計データ上の対応するパターン300との間の位置ずれを算出することで、試料ステージ121の移動誤差を求めることができる。
As shown in FIG. 8, the computer 150 causes the image (that is, the first image generation area 221) until the characteristic pattern 201 </ b> A and the other repeated pattern 201 match the corresponding pattern 300 on the design data. The image of the first area 221a and the image of the second area 221b in the image generation area 221 are moved. The moving distance and moving direction of the image in the first image generation area 221 at this time are the movement of the sample stage 121 that occurs when the sample stage 121 moves from the initial position to the first image generation area 221 (that is, the reference position 210). It corresponds to the error. The movement error of the sample stage 121 corresponds to a deviation of the position after the movement of the sample stage 121 from the movement target position. More specifically, the movement error of the sample stage 121 corresponds to a positional deviation between the characteristic pattern 201A on the image and the corresponding pattern 300 on the design data. Therefore, the computer 150 can obtain the movement error of the sample stage 121 by calculating the positional deviation between the characteristic pattern 201A on the image and the corresponding pattern 300 on the design data.
コンピュータ150は、第1画像生成領域221の画像の移動距離および移動方向からなる移動誤差を記憶装置162内に保存する。コンピュータ150は、試料ステージ121の現在の位置情報を、試料ステージ121の移動誤差に基づいて補正する。この位置情報の補正により、試料ステージ121の位置情報は、設計データ上の位置情報に一致する。
The computer 150 stores a movement error including the movement distance and the movement direction of the image in the first image generation area 221 in the storage device 162. The computer 150 corrects the current position information of the sample stage 121 based on the movement error of the sample stage 121. By correcting the position information, the position information of the sample stage 121 matches the position information on the design data.
次に、コンピュータ150は、ステージ制御装置122に指令を発して試料ステージ121を第1画像生成領域221から第2画像生成領域222に移動させる。試料ステージ121の移動目標位置は、第2画像生成領域222の中心に対応する設計データ上の位置である。試料ステージ121が第2画像生成領域222に移動すると、走査電子顕微鏡100は、ウェーハ124の第2画像生成領域222内の第1領域と第2領域の画像を生成する。
Next, the computer 150 issues a command to the stage controller 122 to move the sample stage 121 from the first image generation area 221 to the second image generation area 222. The target movement position of the sample stage 121 is a position on the design data corresponding to the center of the second image generation region 222. When the sample stage 121 moves to the second image generation area 222, the scanning electron microscope 100 generates images of the first area and the second area in the second image generation area 222 of the wafer 124.
図9は、第2画像生成領域222内の第1領域222aと第2領域222bを示す図である。第2画像生成領域222内の第1領域222aは、第1画像生成領域221内の第2領域221bと重なり合う領域であり、第2画像生成領域222内の第2領域222bは、第3画像生成領域223と重なり合う領域である。コンピュータ150は、第1領域222aの画像と第2領域222bの画像を走査電子顕微鏡100から取得する。そして、コンピュータ150は、第1画像生成領域221内の第2領域221bの画像上のパターンと、第2画像生成領域222内の第1領域222aの画像上のパターンとの間でパターンマッチングを実行する。このパターンマッチングは、第1画像生成領域221内のパターンと、第2画像生成領域222内のパターンとの間の位置合わせ(アライメント)である。
FIG. 9 is a diagram showing the first region 222a and the second region 222b in the second image generation region 222. The first area 222a in the second image generation area 222 is an area that overlaps the second area 221b in the first image generation area 221, and the second area 222b in the second image generation area 222 is the third image generation. This is an area overlapping with the area 223. The computer 150 acquires the image of the first area 222 a and the image of the second area 222 b from the scanning electron microscope 100. Then, the computer 150 performs pattern matching between the pattern on the image of the second area 221b in the first image generation area 221 and the pattern on the image of the first area 222a in the second image generation area 222. To do. This pattern matching is alignment (alignment) between the pattern in the first image generation area 221 and the pattern in the second image generation area 222.
図10は、第1画像生成領域221内の第2領域221bの画像上のパターン201aと、第2画像生成領域222内の第1領域222aの画像上のパターン201bとの間でパターンマッチングを実行している様子を示す模式図である。第2領域221bの画像上のパターン201aと、第1領域222aの画像上のパターン201bは、ウェーハ124上に存在する同じパターンである。言い換えれば、隣接する2つの画像生成領域221,222の2つの画像の両方に、同じパターンが現れている。これら2つの画像の両方に現れるパターンは、隣接する2つの画像生成領域の重なり合う領域内にある。
FIG. 10 shows pattern matching between the pattern 201a on the image of the second area 221b in the first image generation area 221 and the pattern 201b on the image of the first area 222a in the second image generation area 222. It is a schematic diagram which shows a mode that is doing. The pattern 201 a on the image of the second region 221 b and the pattern 201 b on the image of the first region 222 a are the same pattern existing on the wafer 124. In other words, the same pattern appears in both of the two images in the two adjacent image generation regions 221 and 222. A pattern appearing in both of these two images is in an overlapping region of two adjacent image generation regions.
パターン201a,201bは、設計データ上の同じ形状のパターンに基づいて作成されたものであるが、図10に示すように、パターン201a,201bの1つ1つの形状は僅かに異なっている。この形状の相違に起因して、パターン201a,201bの1つ1つの輝度プロファイルも異なっている。輝度プロファイルは、パターンを横切る線分に沿った輝度の分布である。コンピュータ150は、パターン間の形状または輝度プロファイルに基づいて、パターン201aとパターン201bとの間でパターンマッチングをすることができる。結果として、コンピュータ150は、第1領域222aの画像上のパターン201bを、第2領域221bの画像上のパターン201aにそれぞれ位置合わせすることができる。
The patterns 201a and 201b are created based on patterns having the same shape on the design data, but the shapes of the patterns 201a and 201b are slightly different as shown in FIG. Due to the difference in shape, the luminance profiles of the patterns 201a and 201b are also different. A luminance profile is a distribution of luminance along a line segment that traverses the pattern. The computer 150 can perform pattern matching between the pattern 201a and the pattern 201b based on the shape or luminance profile between patterns. As a result, the computer 150 can align the pattern 201b on the image in the first area 222a with the pattern 201a on the image in the second area 221b.
コンピュータ150は、第1領域222aの画像上のパターン201bが、第2領域221bの画像上の対応するパターン201aにそれぞれ一致するまで、第2画像生成領域222の画像(すなわち、第2画像生成領域222内の第1領域222aの画像と第2領域222bの画像)を移動させる。このときの第2画像生成領域222の画像の移動距離および移動方向は、試料ステージ121が、第1画像生成領域221から第2画像生成領域222まで移動したときに生じた試料ステージ121の移動誤差に相当する。より具体的には、試料ステージ121の移動誤差は、第1画像生成領域221の画像上のパターンと、第2画像生成領域222の画像上のパターンとの間の位置ずれに相当する。したがって、コンピュータ150は、第1画像生成領域221の画像上のパターンと、第2画像生成領域222の画像上のパターンとの間の位置ずれを算出することで、試料ステージ121の移動誤差を求めることができる。
The computer 150 determines that the image in the second image generation area 222 (that is, the second image generation area) until the pattern 201b on the image in the first area 222a matches the corresponding pattern 201a on the image in the second area 221b. The image of the first region 222a and the image of the second region 222b) in 222 are moved. The moving distance and moving direction of the image in the second image generation area 222 at this time are the movement errors of the sample stage 121 that occur when the sample stage 121 moves from the first image generation area 221 to the second image generation area 222. It corresponds to. More specifically, the movement error of the sample stage 121 corresponds to a positional deviation between the pattern on the image in the first image generation area 221 and the pattern on the image in the second image generation area 222. Therefore, the computer 150 calculates the displacement between the pattern on the image of the first image generation area 221 and the pattern on the image of the second image generation area 222, thereby obtaining the movement error of the sample stage 121. be able to.
コンピュータ150は、第2画像生成領域222の画像の移動距離および移動方向からなる移動誤差を記憶装置162内に保存する。コンピュータ150は、試料ステージ121の現在の位置情報を、試料ステージ121の移動誤差に基づいて補正する。この位置情報の補正により、試料ステージ121の位置情報は、設計データ上の位置情報に一致する。
The computer 150 stores a movement error including the movement distance and the movement direction of the image in the second image generation area 222 in the storage device 162. The computer 150 corrects the current position information of the sample stage 121 based on the movement error of the sample stage 121. By correcting the position information, the position information of the sample stage 121 matches the position information on the design data.
同様にして、図11に示すように、試料ステージ121を第2画像生成領域222から第3画像生成領域223に移動させる。試料ステージ121の移動目標位置は、第3画像生成領域223の中心に対応する設計データ上の位置である。走査電子顕微鏡100は、第3画像生成領域223内の第1領域223aおよび第2領域223bの画像を生成する。コンピュータ150は、第1領域223aおよび第2領域223bの画像を走査電子顕微鏡100から取得する。そして、コンピュータ150は、第2画像生成領域222内の第2領域222bの画像上のパターンと、第3画像生成領域223内の第1領域223aの画像上のパターンとの間でパターンマッチングを行う。パターンマッチングにより、第2画像生成領域222内のパターンと第3画像生成領域223内のパターンとの位置合わせ(アライメント)が達成される。さらに、コンピュータ150は、試料ステージ121が、第2画像生成領域222から第3画像生成領域223まで移動したときに生じた試料ステージ121の移動誤差を算出し、試料ステージ121の現在の位置情報を、試料ステージ121の移動誤差に基づいて補正する。
Similarly, as shown in FIG. 11, the sample stage 121 is moved from the second image generation area 222 to the third image generation area 223. The movement target position of the sample stage 121 is a position on the design data corresponding to the center of the third image generation region 223. The scanning electron microscope 100 generates images of the first region 223a and the second region 223b in the third image generation region 223. The computer 150 acquires images of the first area 223 a and the second area 223 b from the scanning electron microscope 100. Then, the computer 150 performs pattern matching between the pattern on the image of the second area 222b in the second image generation area 222 and the pattern on the image of the first area 223a in the third image generation area 223. . By pattern matching, alignment (alignment) between the pattern in the second image generation area 222 and the pattern in the third image generation area 223 is achieved. Further, the computer 150 calculates a movement error of the sample stage 121 that occurs when the sample stage 121 moves from the second image generation region 222 to the third image generation region 223, and obtains the current position information of the sample stage 121. The correction is made based on the movement error of the sample stage 121.
同様にして、図12に示すように、試料ステージ121を第3画像生成領域223から第4画像生成領域224に移動させる。試料ステージ121の移動目標位置は、第4画像生成領域224の中心に対応する設計データ上の位置である。走査電子顕微鏡100は、第4画像生成領域224内の第1領域224aの画像を生成する。コンピュータ150は、第1領域224aの画像を走査電子顕微鏡100から取得する。そして、コンピュータ150は、第3画像生成領域222内の第2領域223bの画像上のパターンと、第4画像生成領域224内の第1領域224aの画像上のパターンとの間でパターンマッチングを行う。パターンマッチングにより、第3画像生成領域223内のパターンと第4画像生成領域224内のパターンとの位置合わせ(アライメント)が達成される。さらに、コンピュータ150は、試料ステージ121が、第3画像生成領域223から第4画像生成領域224まで移動したときに生じた試料ステージ121の移動誤差を算出し、試料ステージ121の現在の位置情報を、試料ステージ121の移動誤差に基づいて補正する。走査電子顕微鏡100は、検査領域203の画像を生成し、コンピュータ150は、検査領域203の画像を走査電子顕微鏡100から取得する。コンピュータ150は、検査領域203の画像を用いてパターンの欠陥検査またはパターンの測定などの検査を実行する。
Similarly, as shown in FIG. 12, the sample stage 121 is moved from the third image generation area 223 to the fourth image generation area 224. The movement target position of the sample stage 121 is a position on the design data corresponding to the center of the fourth image generation region 224. The scanning electron microscope 100 generates an image of the first region 224a in the fourth image generation region 224. The computer 150 acquires an image of the first region 224a from the scanning electron microscope 100. Then, the computer 150 performs pattern matching between the pattern on the image of the second area 223b in the third image generation area 222 and the pattern on the image of the first area 224a in the fourth image generation area 224. . By pattern matching, alignment (alignment) between the pattern in the third image generation region 223 and the pattern in the fourth image generation region 224 is achieved. Further, the computer 150 calculates a movement error of the sample stage 121 that occurs when the sample stage 121 moves from the third image generation region 223 to the fourth image generation region 224, and obtains the current position information of the sample stage 121. The correction is made based on the movement error of the sample stage 121. The scanning electron microscope 100 generates an image of the inspection area 203, and the computer 150 acquires the image of the inspection area 203 from the scanning electron microscope 100. The computer 150 uses the image of the inspection area 203 to perform inspection such as pattern defect inspection or pattern measurement.
上述したように、試料ステージ121が移動するたびに試料ステージ121の現在の位置情報が補正されるので、画像上の検査領域203の位置情報は、設計データ上の検査領域203の位置情報に実質的に一致する。コンピュータ150は、試料ステージ121の補正された位置情報に基づいて、検査領域203内の個々のパターンの位置を算出することができる。本実施形態によれば、検査領域203内の個々のパターンの位置を、サブナノメートルオーダーまたはナノメートルオーダーの精度で特定することが可能である。さらに、基準位置210から検査領域203まで最短のルートで試料ステージ121が移動するので、速やかに検査領域203内のパターン検査を実行することができる。
As described above, since the current position information of the sample stage 121 is corrected each time the sample stage 121 moves, the position information of the inspection area 203 on the image is substantially the same as the position information of the inspection area 203 on the design data. Match. The computer 150 can calculate the position of each pattern in the inspection region 203 based on the corrected position information of the sample stage 121. According to this embodiment, it is possible to specify the position of each pattern in the inspection region 203 with sub-nanometer order or nanometer order accuracy. Furthermore, since the sample stage 121 moves along the shortest route from the reference position 210 to the inspection area 203, the pattern inspection in the inspection area 203 can be executed promptly.
図13および図14は、検査領域203内の繰り返しパターンの位置を基準位置210に基づいて特定する工程を説明するフローチャートである。ステップ1では、基準位置210および検査領域(目標領域)203を少なくとも含む複数の画像生成領域221,222,223,224を、隣接する2つの画像生成領域が重なり合うように設定する(図6参照)。ステップ2では、試料ステージ121を第1画像生成領域221(より具体的には基準位置210)に移動させる。ステップ3では、第1画像生成領域221内の第1領域221aと第2領域221bの画像が生成される(図7参照)。
FIG. 13 and FIG. 14 are flowcharts for explaining the process of specifying the position of the repetitive pattern in the inspection area 203 based on the reference position 210. In step 1, a plurality of image generation areas 221, 222, 223, and 224 including at least the reference position 210 and the inspection area (target area) 203 are set so that two adjacent image generation areas overlap (see FIG. 6). . In step 2, the sample stage 121 is moved to the first image generation region 221 (more specifically, the reference position 210). In step 3, images of the first area 221a and the second area 221b in the first image generation area 221 are generated (see FIG. 7).
ステップ4では、第1領域221aの画像上のパターンと、設計データ上の対応するパターンとの間でパターンマッチングが実行される。ステップ5では、パターンマッチングの結果から得られた試料ステージ121の移動誤差に基づいて、試料ステージ121の現在の位置情報が補正される。ステップ6では、画像生成領域の番号を表す“n”に、初期値である2が設定される。ステップ7では、“n”が設定上限か否かが判断される。設定上限は、上記ステップ1で設定された複数の画像生成領域の数に相当する。
In step 4, pattern matching is executed between the pattern on the image of the first region 221a and the corresponding pattern on the design data. In step 5, the current position information of the sample stage 121 is corrected based on the movement error of the sample stage 121 obtained from the pattern matching result. In step 6, an initial value of 2 is set to “n” representing the number of the image generation area. In step 7, it is determined whether “n” is a set upper limit. The setting upper limit corresponds to the number of the plurality of image generation areas set in step 1 above.
“n”が設定上限でない場合は、ステップ8において、試料ステージ121を第n画像生成領域に移動させる。ステップ9では、第n画像生成領域内の第1領域および第2領域の画像が生成される。ステップ10では、第n-1画像生成領域内の第2領域の画像上のパターンと、第n画像生成領域内の第1領域の画像上のパターンとの間でパターンマッチングが実行される。ステップ11では、パターンマッチングの結果から得られた試料ステージ121の移動誤差に基づいて、試料ステージ121の現在の位置情報が補正される。ステップ12では、nに1が加算される。
If “n” is not the set upper limit, in step 8, the sample stage 121 is moved to the nth image generation region. In step 9, images of the first area and the second area in the nth image generation area are generated. In step 10, pattern matching is performed between the pattern on the image of the second area in the n−1th image generation area and the pattern on the image of the first area in the nth image generation area. In step 11, the current position information of the sample stage 121 is corrected based on the movement error of the sample stage 121 obtained from the pattern matching result. In step 12, 1 is added to n.
上記ステップ7において、“n”が設定上限である場合は、ステップ13において、試料ステージ121を第n画像生成領域に移動させる。ステップ14では、第n画像生成領域内の第1領域の画像が生成される。ステップ15では、第n-1画像生成領域内の第2領域の画像上のパターンと、第n画像生成領域内の第1領域の画像上のパターンとの間でパターンマッチングが実行される。ステップ16では、パターンマッチングの結果から得られた試料ステージ121の移動誤差に基づいて、試料ステージ121の現在の位置情報が補正される。ステップ17では、検査領域203の画像が生成される。ステップ18では、検査領域203の画像を用いてパターンの欠陥検査またはパターンの測定などの検査が実行される。
In step 7, if “n” is the upper limit, the sample stage 121 is moved to the nth image generation region in step 13. In step 14, an image of the first area in the nth image generation area is generated. In step 15, pattern matching is performed between the pattern on the image of the second area in the n−1th image generation area and the pattern on the image of the first area in the nth image generation area. In step 16, the current position information of the sample stage 121 is corrected based on the movement error of the sample stage 121 obtained from the pattern matching result. In step 17, an image of the inspection area 203 is generated. In step 18, inspection such as pattern defect inspection or pattern measurement is performed using the image of the inspection region 203.
上述した実施形態は、本発明が属する技術分野における通常の知識を有する者が本発明を実施できることを目的として記載されたものである。上記実施形態の種々の変形例は、当業者であれば当然になしうることであり、本発明の技術的思想は他の実施形態にも適用しうる。したがって、本発明は、記載された実施形態に限定されることはなく、特許請求の範囲によって定義される技術的思想に従った最も広い範囲に解釈されるものである。
The above-described embodiments are described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.
本発明は、パターンの設計データを用いてパターン検査を行うパターン検査装置に適用可能な画像生成方法に利用可能である。
The present invention can be used in an image generation method applicable to a pattern inspection apparatus that performs pattern inspection using pattern design data.
100 走査電子顕微鏡
111 電子銃
112 集束レンズ
113 X偏向器
114 Y偏向器
115 対物レンズ
116 レンズ制御装置
117 偏向制御装置
118 画像取得装置
120 試料チャンバー
121 試料ステージ
122 ステージ制御装置
124 ウェーハ
130 二次電子検出器
131 反射電子検出器
140 ウェーハ搬送装置
150 コンピュータ
161 設計データベース
162 記憶装置
163 入力装置
164 表示装置
201 繰り返しパターン
201A 特徴的なパターン
203 検査領域
210 基準位置
221,222,223,224 画像生成領域 DESCRIPTION OFSYMBOLS 100 Scanning electron microscope 111 Electron gun 112 Focusing lens 113 X deflector 114 Y deflector 115 Objective lens 116 Lens control device 117 Deflection control device 118 Image acquisition device 120 Sample chamber 121 Sample stage 122 Stage control device 124 Wafer 130 Secondary electron detection Device 131 Backscattered electron detector 140 Wafer transfer device 150 Computer 161 Design database 162 Storage device 163 Input device 164 Display device 201 Repetitive pattern 201A Characteristic pattern 203 Inspection area 210 Reference positions 221, 222, 223, and 224 Image generation area
111 電子銃
112 集束レンズ
113 X偏向器
114 Y偏向器
115 対物レンズ
116 レンズ制御装置
117 偏向制御装置
118 画像取得装置
120 試料チャンバー
121 試料ステージ
122 ステージ制御装置
124 ウェーハ
130 二次電子検出器
131 反射電子検出器
140 ウェーハ搬送装置
150 コンピュータ
161 設計データベース
162 記憶装置
163 入力装置
164 表示装置
201 繰り返しパターン
201A 特徴的なパターン
203 検査領域
210 基準位置
221,222,223,224 画像生成領域 DESCRIPTION OF
Claims (5)
- 走査電子顕微鏡を用いた画像生成方法であって、
試料に形成されたパターンの設計データを用いて予め設定された検査領域から最も短い距離にある特徴的なパターンを決定し、
前記決定された特徴的なパターンの位置である基準位置を決定し、
前記基準位置および前記検査領域を少なくとも含む複数の画像生成領域を、隣接する2つの画像生成領域が重なり合うように設定し、
前記基準位置から前記検査領域に向かう方向に、試料ステージを前記複数の画像生成領域に順次移動させ、
前記試料ステージを前記複数の画像生成領域のいずれかに移動させるたびに、その画像生成領域の画像を生成し、かつ少なくとも前記画像を用いて前記試料ステージの移動誤差を算出し、
前記移動誤差に基づいて、前記試料ステージの現在の位置情報を補正し、
前記検査領域の画像を生成する画像生成方法。 An image generation method using a scanning electron microscope,
Using the design data of the pattern formed on the sample, determine the characteristic pattern at the shortest distance from the preset inspection area,
Determining a reference position which is the position of the determined characteristic pattern;
A plurality of image generation areas including at least the reference position and the inspection area are set so that two adjacent image generation areas overlap;
In a direction from the reference position toward the inspection area, sequentially move the sample stage to the plurality of image generation areas,
Each time the sample stage is moved to one of the plurality of image generation areas, an image of the image generation area is generated, and at least the movement error of the sample stage is calculated using the image,
Based on the movement error, correct the current position information of the sample stage,
An image generation method for generating an image of the inspection area. - 前記複数の画像生成領域は、前記基準位置と前記検査領域とをつなぐことができる最小の数の複数の画像生成領域である、請求項1に記載の画像生成方法。 The image generation method according to claim 1, wherein the plurality of image generation areas are a minimum number of the plurality of image generation areas that can connect the reference position and the inspection area.
- 前記試料ステージの移動誤差を算出する工程は、隣接する2つの画像生成領域の2つの画像の両方に現れるパターン間の位置ずれを算出する工程を含む、請求項1または2に記載の画像生成方法。 The image generation method according to claim 1, wherein the step of calculating the movement error of the sample stage includes a step of calculating a positional deviation between patterns appearing in both of two images in two adjacent image generation regions. .
- 前記試料ステージの移動誤差を算出する工程は、画像上の前記特徴的なパターンと、設計データ上の対応するパターンとの位置ずれを算出する工程をさらに含む、請求項3に記載の画像生成方法。 The image generation method according to claim 3, wherein the step of calculating the movement error of the sample stage further includes a step of calculating a positional deviation between the characteristic pattern on the image and a corresponding pattern on the design data. .
- 前記画像生成領域の画像は、前記画像生成領域内の第1領域の画像と、前記画像生成領域内の第2領域の画像を含み、
前記第2領域は、隣接する他の画像生成領域の第1領域と重なり合っている、請求項1乃至4のいずれか一項に記載の画像生成方法。 The image of the image generation area includes an image of a first area in the image generation area and an image of a second area in the image generation area,
5. The image generation method according to claim 1, wherein the second area overlaps a first area of another adjacent image generation area. 6.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2018068263A JP2019178949A (en) | 2018-03-30 | 2018-03-30 | Image generation method |
JP2018-068263 | 2018-03-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2019188296A1 true WO2019188296A1 (en) | 2019-10-03 |
Family
ID=68061447
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2019/010283 WO2019188296A1 (en) | 2018-03-30 | 2019-03-13 | Image generating method |
Country Status (3)
Country | Link |
---|---|
JP (1) | JP2019178949A (en) |
TW (1) | TW202001235A (en) |
WO (1) | WO2019188296A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN111651660B (en) * | 2020-05-28 | 2023-05-02 | 拾音智能科技有限公司 | Method for cross-media retrieval of difficult samples |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000251824A (en) * | 1999-03-01 | 2000-09-14 | Fujitsu Ltd | Electron beam apparatus and stage movement positioning method thereof |
US20110202896A1 (en) * | 2010-02-16 | 2011-08-18 | Deca Technologies Inc. | Adaptive patterning for panelized packaging |
JP2017009434A (en) * | 2015-06-22 | 2017-01-12 | アズビル株式会社 | Image inspection device and image inspection method |
-
2018
- 2018-03-30 JP JP2018068263A patent/JP2019178949A/en active Pending
-
2019
- 2019-03-13 WO PCT/JP2019/010283 patent/WO2019188296A1/en active Application Filing
- 2019-03-22 TW TW108110073A patent/TW202001235A/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000251824A (en) * | 1999-03-01 | 2000-09-14 | Fujitsu Ltd | Electron beam apparatus and stage movement positioning method thereof |
US20110202896A1 (en) * | 2010-02-16 | 2011-08-18 | Deca Technologies Inc. | Adaptive patterning for panelized packaging |
JP2017009434A (en) * | 2015-06-22 | 2017-01-12 | アズビル株式会社 | Image inspection device and image inspection method |
Also Published As
Publication number | Publication date |
---|---|
TW202001235A (en) | 2020-01-01 |
JP2019178949A (en) | 2019-10-17 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5276854B2 (en) | Pattern generation apparatus and pattern shape evaluation apparatus | |
US8295584B2 (en) | Pattern measurement methods and pattern measurement equipment | |
KR101828124B1 (en) | Pattern evaluation method and pattern evaluation device | |
US8507856B2 (en) | Pattern measuring method and pattern measuring device | |
JP5030906B2 (en) | Panorama image synthesis method and apparatus using scanning charged particle microscope | |
JP2008147143A (en) | Imaging recipe generation method and measurement recipe generation method in sem device or sem system, and sem device or sem system | |
KR20170093931A (en) | Pattern measurement apparatus and flaw inspection apparatus | |
JP2019011972A (en) | Pattern edge detection method | |
KR102446053B1 (en) | Charged particle beam device | |
US11468555B2 (en) | Method and apparatus for generating a correction line indicating relationship between deviation of an edge of a wafer pattern from an edge of a reference pattern and space width of the reference pattern, and a computer-readable recording medium | |
WO2019188296A1 (en) | Image generating method | |
JP5868462B2 (en) | Pattern shape evaluation device | |
JP6632863B2 (en) | Electron beam diameter control method and electron beam diameter control device for electron beam inspection / length measurement device, and electron beam inspection / length measurement device | |
US20210343497A1 (en) | Multi-beam inspection methods and systems | |
JP5596812B2 (en) | Pattern generation apparatus and pattern shape evaluation apparatus | |
JP6001945B2 (en) | Pattern measuring apparatus and method | |
JP7303155B2 (en) | Pattern measurement method | |
TWI853181B (en) | Method and system for calibrating a scanning electron microscope | |
JP5463334B2 (en) | Pattern measuring method and pattern measuring apparatus | |
KR20210144796A (en) | How to create an image | |
JP2013178877A (en) | Charged particle beam device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 19775292 Country of ref document: EP Kind code of ref document: A1 |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 19775292 Country of ref document: EP Kind code of ref document: A1 |