JP4634478B2 - Sample inspection apparatus and sample inspection method - Google Patents

Description

  The present invention relates to inspection of a pattern of a sample, and more particularly to inspection of a defect of a very small pattern such as a photomask, a wafer, or a liquid crystal substrate used when manufacturing a semiconductor element or a liquid crystal display (LCD).

  As represented by a 1 gigabit class DRAM, a pattern constituting a large scale integrated circuit (LSI) is going to be on the order of submicron to nanometer. One of the major causes of a decrease in yield in the manufacture of LSI is a defect of a photomask used when an ultrafine pattern is exposed and transferred onto a semiconductor wafer by a photolithography technique. In particular, with the miniaturization of the pattern dimensions of LSIs formed on semiconductor wafers, the dimensions that must be detected as pattern defects have become extremely small. For this reason, an apparatus for inspecting such a defect has been developed.

  On the other hand, with the development of multimedia, LCDs are becoming larger in size of the liquid crystal substrate to 500 mm × 600 mm or more, and patterns such as TFTs formed on the liquid crystal substrate are being miniaturized. Therefore, it is required to inspect a very small pattern defect over a wide range. For this reason, there is an urgent need to develop a sample inspection apparatus for efficiently inspecting defects of a photomask used in manufacturing such a large area LCD pattern and a large area LCD in a short time.

With conventional devices, a sensor for acquiring an image of a sample generates a false image that appears to have a minute pattern due to cosmic rays or electrical noise inside the sensor. There is no problem. Therefore, there is a technique for removing the influence of cosmic rays by installing a sensor for detecting the collision of cosmic rays with the sensor (see Patent Document 1), but the apparatus configuration is large and the configuration is complicated, There is a problem that the influence of noise generated inside the sensor remains.
JP-A-5-312955

(1) The present invention resides in accurate pattern inspection of a sample.
(2) Further, the present invention resides in a pattern inspection that can eliminate a false image of a measurement image that occurs temporarily.

(1) A sample inspection apparatus according to an embodiment of the present invention includes a measurement image generation unit that generates a measurement image by measuring a pattern of a sample;
A difference value between a first pixel in the measurement image and a second pixel adjacent to the first pixel is obtained , and a difference value between the first pixel and the second pixel is obtained. It is determined whether or not a predetermined value is exceeded. As a result of the determination, if the difference value exceeds the predetermined value and the determination of the difference value has not been performed before, the measurement image generation unit is provided with a region of the measurement image. A measurement image pixel difference calculation unit that outputs an instruction to re-measure and generate a second measurement image ;
With
The measurement image generation unit receives the instruction, remeasures the region of the measurement image, and generates a second measurement image,
The sample inspection apparatus further includes:
As a result of determination by the measurement image pixel difference calculation unit, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the 2 A comparison unit that compares the second measurement image with the reference image is provided .
(2) Moreover, the sample inspection apparatus according to the embodiment of the present invention includes a measurement image generation unit that generates a measurement image by measuring a pattern of the sample;
A difference image between the measurement image and the reference image is obtained, a difference value between the first pixel in the difference image and a second pixel adjacent to the first pixel is obtained , and further, the first pixel and the second image are obtained. It is determined whether or not the difference value between the pixels exceeds a predetermined value. As a result of the determination, when the difference value exceeds the predetermined value and the determination of the difference value has not been performed before, the measurement image A difference image pixel difference calculation unit that outputs an instruction to re-measure the region of the measurement image to the generation unit to generate a second measurement image ;
With
The measurement image generation unit receives the instruction, remeasures the region of the measurement image, and generates a second measurement image,
The sample inspection apparatus further includes:
As a result of determination by the difference image pixel difference calculation unit, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the 2 A comparison unit that compares the second measurement image with the reference image is provided .
(3) Moreover, the sample inspection method of the embodiment of the present invention generates a measurement image by measuring a pattern of the sample ,
The difference value between the first pixel in the measurement image and the second pixel adjacent to the first pixel is obtained, and the difference value between the first pixel and the second pixel is a predetermined value. If the difference value exceeds a predetermined value as a result of the determination, and the determination of the difference value has not been performed before, the region of the measurement image is remeasured and the second time Outputs instructions to generate a measurement image,
In response to the instruction, re-measure the area of the measurement image to generate a second measurement image,
As a result of the determination, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the second measurement image and the reference image are compared. Compare the image .
(4) Moreover, the sample inspection method according to the embodiment of the present invention generates a measurement image by measuring a pattern of the sample,
A difference image between the measurement image and the reference image is obtained, a difference value between a first pixel in the difference image and a second pixel adjacent to the first pixel is obtained, and the first pixel and the second pixel are obtained. It is determined whether or not the difference value between the pixel and the pixel exceeds a predetermined value. As a result of the determination, when the difference value exceeds the predetermined value and the difference value has not been previously determined, the measurement is performed. Outputs an instruction to remeasure the area of the image and generate a second measurement image,
In response to the instruction, re-measure the area of the measurement image to generate a second measurement image,
As a result of the determination, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the second measurement image and the reference image are compared. Compare the image .

Hereinafter, the details of the present invention will be described with reference to embodiments.
FIG. 1 is a block diagram illustrating a sample inspection apparatus and a sample inspection method according to an embodiment of the present invention. The sample inspection apparatus 10 inspects a pattern 12 of a sample such as a photomask, a wafer, or a liquid crystal substrate. The sample inspection apparatus 10 inspects the pattern 12 of the sample by eliminating the influence of the false image of the measurement image that is temporarily generated by radiation such as cosmic rays or electrical noise inside the sensor. is there. The sample inspection apparatus 10 measures the transmitted light and reflected light of the pattern 12 of the sample with the measurement image generation unit 14 and generates one or both of the transmitted image and the reflected image. The sample inspection apparatus 10 processes the design data 20 of the pattern of the sample by the reference image generation unit 22 and generates a reference image similar to the measurement image.

  The pixel difference calculation unit 30 includes a measurement image pixel difference calculation unit 32, a difference image pixel difference calculation unit 34, or both. The measurement image pixel difference calculation unit 32 measures the difference value of the difference in output value between adjacent pixels, that is, the amount of inclination, for the measurement image created by the measurement image generation unit 14, and whether the difference value exceeds a predetermined value. Ask for no. The difference image pixel difference calculation unit 34 measures the difference value of the difference between the output values between adjacent pixels for the difference image obtained by obtaining the difference value between the output values of the measurement image and the reference image, and calculates the difference value. Is determined whether or not exceeds a predetermined value. Here, the standard image is a reference image created by the reference image generation unit 22, or a measurement image created by the measurement image generation unit 14, for example, an image obtained by filtering the reflection image with respect to a transmission image to be inspected or an inspection. This is an image used as a reference including an image obtained by applying a filtering process to a transmission image with respect to a reflection image of an object, or an identical pattern at a different location on the same sample.

  Both the measurement image pixel difference calculation unit 32 and the difference image pixel difference calculation unit 34 issue an instruction to the measurement image generation unit 14 when the difference in output value between adjacent pixels exceeds a predetermined value. Upon receipt of the instruction, the measurement image generation unit 14 measures the pattern of the region including these pixels again to obtain the measurement image again. Since the false image of the measurement image due to cosmic rays, electrical noise, or the like is generated due to temporary influence, the false image can be eliminated by measuring again.

  The sample inspection apparatus 10 includes a comparison unit 24. The pixel difference calculation unit 30 compares the measurement image from which the false image is excluded and the reference image, and determines that the defect is a defect when the difference exceeds a predetermined value. Perform pattern inspection. The comparison unit 24 uses the reference image generated by the reference image generation unit 22 as a standard image, performs a D-DB comparison with the measurement image from which the false image is excluded, or on the same sample generated by the measurement image generation unit 14 A measurement image from which the same pattern at different locations is imaged and the false image is eliminated is used as a reference image, and a DD comparison is made with the measurement image from which the false image is eliminated.

(Sample inspection equipment)
FIG. 2 is a conceptual diagram showing the internal configuration of the sample inspection apparatus 10. The sample inspection apparatus 10 inspects a pattern defect of the sample 100 using a substrate such as a mask or a wafer as the sample 100. The sample inspection apparatus 10 includes an optical image acquisition unit 110, a control system circuit 150, and the like. The optical image acquisition unit 110 includes an autoloader 112, an illuminating device 114 that generates transmitted illumination light, an illuminating device 1140 that generates reflected illumination light, an XYθ table 116, an XYθ motor 118, a laser length measurement system 120, and a magnifying optical device. A system 122, a piezo element 124, a CCD that receives transmitted light and reflected light, a light receiving unit 126 such as a TDI or a photodiode array, a sensor circuit 128, and the like are provided. In the control system circuit 150, a CPU 152 serving as a control computer is connected to a mass storage device 156, a memory device 158, a display device 160, a printing device 162, an autoloader control circuit 170, a table control circuit via a bus 154 serving as a data transmission path. 172, an autofocus control circuit 174, a development circuit 176, a reference circuit 178, a comparison circuit 180, a position circuit 182 and the like.

  The pixel difference calculation unit 30 may be provided in the sensor circuit 128 or the comparison circuit 180 or may be connected to the sensor circuit 128 or the comparison circuit 180. The development circuit 176, the reference circuit 178, the comparison circuit 180, and the position circuit 182 are connected to each other as shown in FIG.

  The measurement image generation unit 14 in FIG. 1 can be configured by the optical image acquisition unit 110 in FIG. The reference image generation unit 22 can be configured by a development circuit 176 and a reference circuit 178. The comparison unit 24 can be configured by the comparison circuit 180. In FIG. 2, description of components other than those necessary for describing the present embodiment is omitted. The sample inspection apparatus 10 usually includes other necessary configurations.

(Operation of optical image acquisition unit)
The sample 100 is automatically transported from the autoloader 112 driven by the autoloader control circuit 170 and placed on the XYθ table 116. The sample 100 is irradiated with light from above by the illumination device 114. Further, the sample 100 is irradiated with light from below by the illumination device 1140. Below the sample 100, an magnifying optical system 122, a light receiving unit 126, and a sensor circuit 128 are arranged. The light transmitted through or reflected by the sample 100 such as an exposure mask forms an optical image on the light receiving unit 126 via the magnifying optical system 122. The autofocus control circuit 174 controls the piezo element 124 in order to absorb the deflection of the sample 100 and the fluctuation of the XYθ table 116 in the Z-axis direction (perpendicular to the X-axis and the Y-axis). Align.

  FIG. 3 is a diagram for explaining a measurement image acquisition procedure. The inspection area of the sample 100 is virtually divided by the scan width W in the Y-axis direction. That is, the inspection area is virtually divided into a plurality of strip-like stripes 102 having a scan width W. Further, the XYθ table 116 is controlled so that the divided stripes 102 are continuously scanned. The XYθ table 116 moves along the X axis, and the measurement image is acquired as the stripe 102. In FIG. 3, the stripe 102 has a rectangular shape having a scan width W in the Y-axis direction and a longitudinal direction having a length in the X-axis direction. The light transmitted through the sample 100 or the light reflected by the sample 100 enters the light receiving unit 126 through the magnifying optical system 122. On the light receiving unit 126, a part of a strip-shaped region of a virtually divided pattern as shown in FIG. 3 is formed as an enlarged optical image. Images with a scan width W as shown in FIG. 3 are continuously received. After acquiring the image in the first stripe 102, the light receiving unit 126 continuously inputs the image of the scan width W while moving the image in the second stripe 102 in the opposite direction. The scan width W is about 2048 pixels, for example. When acquiring the image in the third stripe 102, the image is acquired while moving in the direction opposite to the direction in which the image in the second stripe 102 is acquired, that is, in the direction in which the image in the first stripe 102 is acquired. To do.

  The XYθ table 116 is driven by the table control circuit 172 under the control of the CPU 152. It can be moved by a drive system such as a three-axis (XY-θ) motor 118 driven in the X-axis direction, Y-axis direction, and θ-direction. For example, step motors can be used as these X motor, Y motor, and θ motor. The movement position of the XYθ table 116 is measured by the laser length measurement system 120 and supplied to the position circuit 182. The optical image received by the light receiving unit 126 becomes electronic data of a measurement image by the sensor circuit 128. The optical image of the sample 100 output from the sensor circuit 128 is sent to the comparison circuit 180 together with data indicating the position of the sample 100 on the XYθ table 116 output from the position circuit 182.

(Reference image generation)
The design data 20 used when forming the pattern of the sample 100 is stored in the mass storage device 156. The design data 20 is input from the mass storage device 156 to the expansion circuit 176 by the CPU 152. As a design data development process, the development circuit 176 converts the design data of the sample 100 into binary or multivalued original image data, and the original image data is sent to the reference circuit 178. The reference circuit 178 performs an appropriate filter process on the original image data to generate a reference image. It can be said that the measurement image obtained from the sensor circuit 128 is in a state in which the filter is activated by the resolution characteristic of the magnifying optical system 122, the aperture effect of the light receiving unit 126, and the like. In this state, since there is a difference between the measurement image and the original image data on the design side, the original image data on the design side is filtered by the reference circuit 178 so that the measurement image can be matched.

  The measurement image pixel difference calculation unit 32 obtains the difference value of the difference between the output values between adjacent pixels of the measurement image, and when the difference value exceeds a predetermined value, measures the region including these pixels again and compares them. Find the target measurement image. The difference image pixel difference calculation unit 34 measures the difference value of the difference between the output values of adjacent pixels for the difference image obtained by calculating the difference between the output values of the measurement image and the reference image, and the difference value is a predetermined value. Judge whether or not it exceeds. If so, the measurement image generation unit 14 is instructed to measure the region including these pixels again. The reference image for obtaining the difference value is a reference image generated by the reference circuit, or a transmission image obtained by capturing the same pattern at different locations on the sample with respect to the transmission image, or an image obtained by filtering the reflection image at the same location, In addition, a reflection image obtained by capturing the same pattern on the sample with respect to the reflection image, or an image obtained by filtering the transmission image can be used.

  The sample 100 on the XYθ table 116 is automatically discharged by the autoloader control circuit 170 after the inspection is completed. Note that the optical image is, for example, 8-bit unsigned data, and expresses the brightness gradation of each pixel.

(Re-acquisition of measurement image)
The pixel difference calculation unit 30 obtains a difference value between adjacent pixels in the X direction, the Y direction, or both directions of the measurement image, or obtains a difference value between adjacent pixels in the X direction, the Y direction, or both directions of the difference image. The inclination between the pixels in the direction, the Y direction, or both directions is calculated and compared with a predetermined value set in advance. When an inclination exceeding a predetermined value is measured, the same stripe is acquired again without proceeding with acquisition of the next stripe. As a result, a measurement image that is not affected by a temporary false image can be acquired, and high-sensitivity inspection can be performed.

(First embodiment)
FIG. 4 shows two pixels A and B adjacent to each other in the X direction of the measurement image 16 and three adjacent pixels C, D, and E. Pixels A and B in FIG. 4 have pixel values a and b, respectively. The pixel value has a luminance of 0 to 255 gradations, for example. For example, the pixel value can be defined as the darkest in the 0th gradation and the brightest in the 255th gradation. The X direction may be the Y direction or another direction. The light receiving unit 126 used here may be a time delay integration sensor using two or more line sensors each including two or more pixels.

  When the absolute value of the difference value (b−a) exceeds the predetermined value Z (| b−a |> Z) with respect to the pixel values a and b of the two pixels A and B, the pixel value a or b is A false image that is not an optical image of the pattern is determined, and a stripe image including the pixels A and B is acquired again. That is, if the absolute value of the difference value (b−a) exceeds a predetermined inclination amount, it is determined as a false image. Thereby, the false image by temporary influences, such as a cosmic ray, can be excluded. As the predetermined value Z, for example, a value of about Z = 100 is used.

  FIG. 5 is a flowchart illustrating the inspection method according to the first embodiment. First, the sample inspection apparatus 10 is initialized and, for example, a flag flag is set to 0 (step S1). Next, the measurement image generator 14 creates a measurement image 16 (step S2). It is checked whether or not the difference value between adjacent pixels in the measurement image 16 is equal to or smaller than a predetermined value Z (step S3). When the difference value between the pixels is equal to or smaller than the predetermined value Z, a normal pattern defect inspection is performed (step S6). When the difference value between adjacent pixels is equal to or greater than the predetermined value Z, the value of the flag flag indicating whether or not the process of step S3 has been performed on the same pixel before is checked. When the flag flag is 1, since the process of step S3 has already been performed for the same pixel, a normal pattern defect inspection is performed (step S6). When the flag flag is 0, the process of step S3 has not yet been performed for the same pixel. Therefore, in order to generate the measurement image 16 again, the flag flag is set to 1, and the process proceeds to the measurement image generation process (step S5).

  Since false images such as cosmic rays are due to temporary influences, the influence of false images such as cosmic rays can be eliminated by measuring the same pixel again in this way. These inspections are performed on all the pixels of the measurement image, or, if necessary, pixels that require particularly high precision, or pixels that have a high probability of generating a false image.

(Second Embodiment)
FIG. 6 shows pixel values (vertical axis) with respect to adjacent pixels (horizontal axis) in the X direction, and in particular, pixel values of brightness of three pixels C, D, and E adjacent in the X direction in FIG. That is, output data c, d, and e are shown. The X direction may be the Y direction or another direction. With respect to the pixel values c, d, e of the three pixels C, D, E, the black portions (c <th (v ) And e <th (v)) or a white value (c> th (w) and e> th (w)) equal to or greater than a predetermined value th (w), and a difference value that is a difference between the pixel values c and e. When it is determined that the absolute value of (ce) is a flat region (| ce− <z) that is equal to or smaller than the predetermined value z, the pixel value d of the center pixel D and the pixel values c of both ends, or e When the absolute value of the difference value (dc) or (ed), which is the difference between the two values, exceeds a predetermined value Z1 (| dc |> Z1 or | ed−> Z1), the pixel value d is determined to be a false image that is not an optical image of the pattern, and an image of a stripe including the pixel D is obtained again for inspection.

  As a result, the pattern inspection of the sample can be performed without being affected by a false image due to a temporary influence such as cosmic rays in a flat region. Each predetermined value typically has a value of about th (v) = 60, th (w) = 230, z = 5, and Z1 = 10. As described above, the false image inspection using three pixels has been described. However, if the number of pixels is increased, the processing becomes complicated, but the accuracy can be further improved.

(Third embodiment)
FIG. 7 is a flowchart showing a procedure for inspecting a false image using a difference image between a measurement image and a reference image instead of the measurement image 16 of FIG. As shown in FIG. 7, after the measurement image is collected (step S2), a reference image is generated from the transferred design data (step S31) to generate a reference image, or a reference image serving as a reference is obtained from the measurement image. Select (step S32). A difference image is generated by taking a difference in pixel value between the measurement image to be inspected and the reference image obtained in step S32 (step S33). Similar to the first or second embodiment, for adjacent two or three pixels, it is determined whether the difference value between the pixels is equal to or smaller than a predetermined value Z2 (step S34). When the value is equal to or smaller than the predetermined value Z2, the process proceeds to a normal defect inspection process (step S6). When the value is equal to or greater than the predetermined value Z2, it is estimated that the influence of a false image such as cosmic rays is performed, and processing similar to the flowchart of FIG. 5 is performed (steps S4 and S5). In this way, by acquiring the stripe image again, even if there is an arbitrary pattern in the measurement pattern data, it is possible to perform the inspection without being influenced by the false image due to the influence of cosmic rays or the like.

(Fourth embodiment)
FIG. 8 is a flowchart for processing similar to that of FIG. 7 for the difference image between the measurement image of the transmitted light and the measurement image of the reflected light. As shown in FIG. 8, a transmission measurement image and a reflection measurement image are collected (step S21). Thereafter, the reflection measurement image is subjected to appropriate filter processing such as pixel value inversion, and a reference image similar to the transmission image is generated (step S311). Next, a difference image is generated by taking a difference in pixel value between the transmission measurement image and the reference image obtained in step S311 (step S312). Similar to the first to third embodiments, for adjacent two or three pixels, it is determined whether the difference value between the pixels is equal to or smaller than a predetermined value Z3 (step S313). If the value is equal to or smaller than the predetermined value Z3, the process proceeds to a normal defect inspection process (step S6). If the value is equal to or greater than the predetermined value Z3, it is estimated that the influence of a false image such as cosmic rays is performed, and the same processing as the flowchart of FIG. 5 or 7 is performed (steps S4 and S5). Note that a reference image similar to the reflection measurement image may be created by performing an appropriate filtering process on the transmission measurement image, and a difference image between the reference image and the reflection measurement image may be created.

(Fifth embodiment)
In FIG. 9, the horizontal axis indicates the position of the X-axis pixel, and the vertical axis indicates the position of the Y-axis pixel. FIG. 9 shows nine pixels adjacent to the intersection of the X1 to X3 axes and the Y1 to Y3 axes of the measurement image 16. In FIG. 10, the horizontal axis indicates the position of the Y-axis pixel, and the vertical axis indicates the pixel value. FIG. 10 shows pixel values of three adjacent pixels with respect to the X1 axis (thick broken line), the X2 axis (fine broken line), and the X3 axis (one-point broken line), and three pixels on the Y1 axis (X1Y1, X2Y1, X3Y1). Of the pixel values (x1y1, x2y1, x3y1), the slope components of the pixel values (x1y2, x2y2, x3y2) of the Y2 axis three pixels (X1Y2, X2Y2, X3Y2), and the Y3 axis three pixels (X1Y3, The gradient components of the pixel values (x1y3, x2y3, x3y3) of X2Y3, X3Y3) are shown. As a result, the difference between the pixel value x2y2 of the center pixel X2Y2 and the pixel value of the adjacent pixel X2Y1 or X2Y3 on the X2 axis becomes the pixel value of the center pixel X1Y2 on the X1 axis and the pixel values X1Y1 or X1Y3 on both ends. If the difference value is larger than the predetermined value Z4 by more than the difference value between the pixel value of the center pixel X3Y2 of the X3 axis and the pixels X3Y1 or X3Y3 at both ends, it is determined as noise due to the influence of cosmic rays, The pixel stripe image is acquired again. That is, the measurement image pixel difference calculation unit, when the difference between the difference value between two adjacent pixels of the measurement image or the difference image and the difference value between the pixels adjacent to each pixel exceeds a predetermined value, The pattern of the area to be included is measured again.

  Thereby, it is possible to perform the pattern inspection without being affected by the false image of the measurement image due to the influence of cosmic rays or the like. As the predetermined value Z4, a value of about Z4 = 20 is typically used. In particular, when cosmic rays are incident substantially parallel to the sensor surface, a linear false image is generated in the measurement image. Therefore, by measuring adjacent pixel values in a plurality of directions of two or more different directions, it is possible to detect a false image due to cosmic rays more accurately. Moreover, the angle which a several direction cross | intersects may be orthogonal or may be another angle. The light receiving unit 126 used here may be a time delay integration sensor using two or more line sensors each including three or more pixels.

  The embodiments have been described above with reference to specific examples. As shown in these embodiments, a false image due to radiation such as cosmic rays incident on the sensor or electrical noise generated inside the sensor is detected, and a stripe including the false image is reexamined to detect the false image. Pseudo defects can be suppressed and inspection with high detection sensitivity can be performed. The inspection in these embodiments is performed for all the pixels of the measurement image, or, if necessary, only pixels that require particularly high precision, or only pixels that have a high probability of generating false images. You can go.

  In the above description, what is described as “to part”, “to circuit” or “to process” and “to step” can be configured by a computer-operable program. Or you may make it implement by not only the program used as software but the combination of hardware and software. Alternatively, a combination with firmware may be used. Alternatively, a combination of these may be realized. When configured by a program, the program is recorded on a recording medium such as a magnetic disk device, a magnetic tape device, an FD, or a ROM (Read Only Memory).

  The present invention is not limited to these specific examples. In each embodiment, the inspection position is scanned by moving the XYθ table 116. However, the XYθ table 116 may be fixed and other optical systems may be moved. That is, relative movement may be performed. In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. In addition, all sample inspection apparatuses that include the elements of the present invention and whose design can be appropriately changed by those skilled in the art are included in the scope of the present invention.

It is a block diagram for demonstrating the sample inspection apparatus and sample inspection method in embodiment. It is a conceptual diagram which shows the internal structure of the sample inspection apparatus in embodiment. It is a figure for demonstrating the acquisition procedure of a measurement image. It is a figure which shows the adjacent pixel of a measurement image. It is a flowchart which takes the difference value between the pixels of a measurement image, and detects a false image. It is a figure which shows the pixel value of the adjacent pixel of a measurement image. It is a flowchart which takes the difference value between the pixels of the difference image of a measurement image and a reference image, and detects a false image. It is a flowchart which takes the difference value between the pixels of the difference image of a transmission measurement image and a reflection measurement image, and detects a false image. It is a figure which shows the adjacent pixel of the X direction of a measurement image, and a Y direction. It is a figure which shows the change of the pixel value of the adjacent pixel of the X direction of a measurement image, and a Y direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sample inspection apparatus 12 ... Sample pattern 14 ... Measurement image generation part 16 ... Measurement image 20 ... Sample pattern design data 22 ... Reference image generation part 24 ... Comparison unit 30 ... Pixel difference calculation unit 32 ... Measurement image pixel difference calculation unit 34 ... Difference image pixel difference calculation unit 100 ··· Sample 102 · · Stripe 110 · · Optical image acquisition unit 112 · · Autoloader 114・ ・ Transmission illumination device 1140 ・ Reflection illumination device 116 ・ ・ XYθ table 118 ・ ・ XYθ motor 120 ・ ・ Laser measurement system 122 ・ ・ Magnification optical system 124 ・ ・ Piezo element 126 ・ ・ Light receiving unit (sensor)
128..Sensor circuit 150..Control system circuit 152..CPU
154 ·· Bus 156 · · Mass storage device 158 · · Memory device 160 · · Display device 162 · · Printing device 170 · · Autoloader control circuit 172 · · Table control circuit 174 · · Autofocus control circuit 176 · · Expansion circuit 178 .. Reference circuit 180 .. Comparison circuit 182 .. Position circuit

Claims (8)

A measurement image generator for measuring a pattern of the sample to generate a measurement image;
A difference value between a first pixel in the measurement image and a second pixel adjacent to the first pixel is obtained , and a difference value between the first pixel and the second pixel is obtained. It is determined whether or not a predetermined value is exceeded. As a result of the determination, if the difference value exceeds the predetermined value and the determination of the difference value has not been performed before, the measurement image generation unit is provided with a region of the measurement image. A measurement image pixel difference calculation unit that outputs an instruction to re-measure and generate a second measurement image ;
With
The measurement image generation unit receives the instruction, remeasures the region of the measurement image, and generates a second measurement image,
The sample inspection apparatus further includes:
As a result of determination by the measurement image pixel difference calculation unit, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the 2 A sample inspection apparatus comprising a comparison unit for comparing a second measurement image with the reference image . The sample inspection apparatus according to claim 1,
The measurement image pixel difference calculation unit obtains a difference value between two pixels at both ends and a difference value between two pixels at the center and the end of three adjacent pixels centered on the first pixel in the measurement image , and calculates 2 at both ends. A sample inspection apparatus that outputs the instruction when a difference value between pixels is smaller than a predetermined value and a difference value between two pixels at the center and the end exceeds a predetermined value. The sample inspection apparatus according to claim 1,
Measuring image pixel difference calculating unit includes: the first pixel in the measurement image, the first pixel and the difference values for between the second pixel adjacent to the first direction, the first When the difference in the difference value between the third pixel adjacent to the pixel in the second direction and the fourth pixel adjacent to the second pixel in the second direction exceeds a predetermined value , Sample inspection device that outputs instructions . A measurement image generator for measuring a pattern of the sample to generate a measurement image;
A difference image between the measurement image and the reference image is obtained, a difference value between the first pixel in the difference image and a second pixel adjacent to the first pixel is obtained , and further, the first pixel and the second image are obtained. It is determined whether or not the difference value between the pixels exceeds a predetermined value. As a result of the determination, when the difference value exceeds the predetermined value and the determination of the difference value has not been performed before, the measurement image A difference image pixel difference calculation unit that outputs an instruction to re-measure the region of the measurement image to the generation unit to generate a second measurement image ;
With
The measurement image generation unit receives the instruction, remeasures the region of the measurement image, and generates a second measurement image,
The sample inspection apparatus further includes:
As a result of determination by the difference image pixel difference calculation unit, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the 2 A sample inspection apparatus comprising a comparison unit for comparing a second measurement image with the reference image . The sample inspection apparatus according to claim 4, wherein
The difference image pixel difference calculation unit obtains a difference value between two pixels at both ends and a difference value between two pixels at the center and the end of three adjacent pixels centered on the first pixel in the difference image . A sample inspection apparatus that outputs the instruction when a difference value between pixels is smaller than a predetermined value and a difference value between two pixels at the center and the end exceeds a predetermined value. The sample inspection apparatus according to claim 4, wherein
The difference image pixel difference calculating unit includes: the first pixel in the difference image, the difference values for between the first pixel and the second pixel adjacent to the first direction, the first When the difference in the difference value between the third pixel adjacent to the pixel in the second direction and the fourth pixel adjacent to the second pixel in the second direction exceeds a predetermined value , Sample inspection device that outputs instructions . Measure the pattern of the sample to generate a measurement image ,
The difference value between the first pixel in the measurement image and the second pixel adjacent to the first pixel is obtained, and the difference value between the first pixel and the second pixel is a predetermined value. If the difference value exceeds a predetermined value as a result of the determination, and the determination of the difference value has not been performed before, the region of the measurement image is remeasured and the second time Outputs instructions to generate a measurement image,
In response to the instruction, re-measure the area of the measurement image to generate a second measurement image,
As a result of the determination, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the second measurement image and the reference image are compared. A sample inspection method that compares images . Measure the pattern of the sample to generate a measurement image,
A difference image between the measurement image and the reference image is obtained, a difference value between a first pixel in the difference image and a second pixel adjacent to the first pixel is obtained, and the first pixel and the second pixel are obtained. It is determined whether or not the difference value between the pixel and the pixel exceeds a predetermined value. As a result of the determination, when the difference value exceeds the predetermined value and the difference value has not been previously determined, the measurement is performed. Outputs an instruction to remeasure the area of the image and generate a second measurement image,
In response to the instruction, re-measure the area of the measurement image to generate a second measurement image,
As a result of the determination, when the difference value does not exceed a predetermined value, the measurement image is compared with a reference image, and when the difference value exceeds a predetermined value, the second measurement image and the reference image are compared. A sample inspection method that compares images .

Images