JP2011232070A - Measuring method and inspection device for recess depth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method and an inspection device for recess depth with which the recess depth can be detected with high accuracy.SOLUTION: In a measuring method of recess depth including an image obtaining step S1 of obtaining images in which the recess D of a target W to be measured are shown with shading by irradiating light substantially orthogonal to the object W to be measured in which the recess D is formed and making shading in the circumference of the recess D, a calculating step S5 is included in which the recess depth is calculated based on a gradation value substantially from the center of the portion (recess image D') corresponding to the recess D of the images towards the circumference.

Description

  The present invention relates to a recess depth measuring method and an inspection apparatus for measuring the depth of a recess formed in an object to be measured from an image. In particular, the present invention relates to a recess depth measuring method and an inspection apparatus suitable for inspecting the depth of a recess formed in a silicon substrate.

  Conventionally, a method for measuring the depth of a recess formed in a measurement object from the image has been devised. This type of measurement method is described in Patent Document 1 and Patent Document 2, for example.

  According to the method for measuring the depth of the recess described in Patent Document 1, an image of a portion including the recess of the measurement object is obtained using a digital camera with a card-type hard disk, and then the outside of the recess is removed from the image by a personal computer (Personal Computer). A method is described in which the diameter is extracted and the recess depth is detected based on the correlation between the outer diameter and depth of the recess. Thereby, it can detect in a short time and low cost compared with the case where a recessed part depth is directly measured using a gauge, a laser displacement meter, etc.

  In addition, the method for measuring the depth of the recess described in Patent Document 2 acquires an image of a portion including the probe contact trace (recess) of the semiconductor device (measurement object) using a CCD camera (Charge Coupled Device Camera). After transferring to the image processing unit, the image processing unit extracts the recess information such as the area, size and density of the probe contact trace (recess) from the image, and the recess information and the depth of the probe contact trace (recess depth). And a method of detecting the depth of the probe contact trace (recess depth) based on the correlation with the depth). Thereby, the depth of the recess can be detected easily and in a short time.

Japanese Patent Laid-Open No. 10-2221028 JP 2001-345358 A

  However, the method for measuring the depth of the recess described in Patent Document 1 and Patent Document 2 extracts the recess information such as the outer diameter and area of the recess from the images, and collates the recess information with the correlation with the recess depth. Since the corresponding recess depth is detected, there is a problem that the recess depth becomes the same when the outer diameter, the area, etc. of the recess are the same.

  Therefore, in order to solve the above problems, the problem is that when detecting the depth of the recess from the image of the measurement object in which the recess is formed, even when the outer diameter, area, etc. of the recess are the same, An object of the present invention is to provide a method and an inspection device for measuring the depth of a recess that can detect the difference in depth between the respective recesses.

  In order to solve the above-mentioned problem, the method for measuring the depth of the recess according to the present invention causes the measurement object to be irradiated with light in a direction substantially orthogonal to the measurement object on which the recess is formed, thereby causing a shadow on the periphery of the recess. In this state, the method for measuring the depth of the concave portion has an image acquisition step of acquiring an image in which the concave portion of the measurement object is displayed in gray, and a gradation from a substantially center to a peripheral portion of the portion corresponding to the concave portion of the image. A calculation step for calculating the recess depth based on the value is provided.

  According to the present invention, in the calculation step, the depth of the concave portion is calculated based on a gradation value from approximately the center to the peripheral edge of the portion corresponding to the concave portion of the shaded image, thereby corresponding to the concave portion of the image. Even if the outer diameter, area, etc. of the portion to be processed are the same, the gradation values from the substantially center to the periphery of the portion corresponding to the concave portion of the image are different from each other. Can detect differences in depth.

  Here, the gray-scaled image is preferably expressed by a gradation value of 16 or more gradations, and may be expressed by 256 gradations or 65,536 gradations. It may be expressed as This is because the accuracy of the recess depth can be improved as the number of gradations increases.

  The grayscale image may be gray scale or RGB full color (Red, Green, Blue Full Color).

  One aspect of the present invention is characterized in that, in the calculation step, the recess depth is set to a maximum value calculated in at least two different directions from a substantial center of a portion corresponding to the recess of the image. .

  According to the present invention, the calculated value calculated in one direction from the approximate center of the portion corresponding to the concave portion of the image is improperly smaller than the actually measured value of the concave depth due to the presence of foreign matter. Even if it is, the calculated value calculated for the other direction is adopted as the recessed portion depth without adopting the calculated value as the recessed portion depth, so that the calculated value of the calculating step deviates from the actually measured value. The reliability of the calculation process can be ensured.

  The depth of the recess may be calculated for each of two directions orthogonal to each other, may be calculated for each of two directions opposite to each other, or may be calculated in three directions, four directions, five directions, or six different from each other. Each direction may be calculated. This is because if the calculation directions of the calculation steps are close, all calculated values may deviate from the actually measured values.

  One aspect of the present invention is characterized in that a correction step for correcting the depth of the recess in the calculation step so as to approach the actual measurement value based on a correlation with the actual measurement value is provided. According to the present invention, the depth of the recess in the calculation step can be made closer to the actual measurement value.

  The inspection apparatus according to the present invention includes a positioning unit provided with a mounting unit on which a measurement object having a concave portion can be mounted, and a counter unit that is opposed to the mounting unit described above with a predetermined interval. An inspection apparatus comprising: an illuminating unit that irradiates light toward the placement unit of the positioning unit; and an imaging unit that captures a light and shaded image by photographing the placement unit side of the positioning unit. A calculation means for executing at least the calculation step of the method for measuring a recess depth according to any one of claims 1 to 3 is provided for the image.

  According to the present invention, when the measurement object having a recess is placed on the placement part of the positioning unit, the light of the illumination unit irradiates the surface of the measurement object from substantially directly above the measurement object. In addition, the imaging means captures the image of the surface of the measurement object from approximately right above the measurement object and obtains an image displayed with shading, and the calculation means measures the depth of the recess with respect to the shading displayed image. Since at least the calculation step of the method is executed, the depth of the recess of the measurement object can be detected in a short time without contact.

  Here, the imaging means is, for example, a digital camera (Digital Camera), a digital video camera (Digital Video Camera), or a CCD camera (Charge Coupled Devices Camera).

  In addition, it is preferable that the image displayed in light and shade is represented by the gradation or brightness of the image with gradations of 16 gradations or more, and may be represented with 256 gradations or with 65,536 gradations. May be.

  The grayscale image may be gray scale or RGB full color (Red, Green, Blue Full Color).

  One aspect of the present invention is characterized by comprising transfer means capable of transferring the grayscale displayed image from the imaging means to the calculation means. According to the present invention, it is possible to move the shaded image easily and in a short time compared to the case where the shaded image is moved from the imaging unit to the computing unit via the recording medium.

  Here, the transfer unit may be configured to transfer the grayscale image by electrically or optically connecting the imaging unit and the calculation unit by an electric wire or an optical fiber, The image displayed in grayscale may be transferred from the imaging unit to the calculation unit by wireless, infrared, laser, or the like.

  As described above, according to the present invention, the recess depth is calculated on the basis of the gradation value from the approximate center to the periphery of the portion corresponding to the recess of the shaded image. An excellent effect that it can be detected can be achieved.

It is process drawing of the measuring method of the recessed part depth of embodiment which concerns on this invention. It is a schematic perspective view which shows typically the inspection apparatus of embodiment which concerns on this invention. It is a partial expanded longitudinal cross-sectional view which shows typically the recessed part formed in the measuring object. It is an image figure which shows typically the state which image | photographed the surface of the measuring object of FIG. 5 is a gradation change graph showing an example in which the gradation value of each pixel is measured along the center line V in FIG. 4. It is an image figure which shows typically the state which binarized FIG. It is explanatory drawing which shows the identification method of the center position of a recessed part image. It is explanatory drawing which shows the calculation method of the calculated value of a recessed part depth. It is an enlarged longitudinal cross-sectional view which shows an example of a recessed part typically. FIG. 10 is a partially enlarged view of FIG. 9. It is explanatory drawing which shows the calculation direction of a recessed part depth. It is a scatter diagram which shows the correlation of the measured value of a recessed part depth, and a calculated value.

[Measurement method of recess depth]
First, with reference to FIG. 1, a method for measuring a recess depth according to an embodiment of the present invention will be described. FIG. 1 is a process diagram of a method for measuring a recess depth. As shown in FIG. 1, the method for measuring the depth of the recess includes an image acquisition step S <b> 1 for acquiring an image of a measurement object on which a recess is formed, and a portion corresponding to the recess from the image (hereinafter referred to as a recess image). .)), An image processing step S3 for correcting the concave image, a maximum gradation acquisition step S4 for detecting the maximum gradation value of the concave image, and the calculated value of the concave depth. In this method, the calculation step S5 to be calculated and the correction step S6 to correct the calculation value of the calculation step S5 are sequentially executed.

  In the image acquisition step S1, as shown in FIG. 2, the measurement object W is irradiated with light Light that is substantially orthogonal to the surface of the measurement object W, and the light irradiation range S is applied to the surface of the measurement object W. In this state, the inner part of the light irradiation range S is photographed by the camera 130 (imaging means) from a position facing the surface of the measurement object W, and an image displayed in grayscale is acquired.

  The image acquired by this image acquisition step S1 is gray scale (monochrome halftone), and the luminance or brightness of each pixel of the image is displayed in shades of 256 gradations. The 256 gradations represent black to white with gradation values from 0 to 255. Further, the number of pixels of the image is not limited, but it is preferable that the recessed image in the image has at least 20 pixels. This is because if the number of pixels in the concave image is small, the accuracy of the calculated value of the concave depth is lowered. In the present embodiment, the number of pixels of the concave image is set in a range from 20 pixels to 90 pixels.

  The image format of the image is not limited. For example, bitmap (BMP: Bit Map), JPEG (Joint Photographic Group), GIF (Graphic Interchange Format), or TIFF (TIFF: Tagged ImageFlame). ).

  Here, FIG. 3 is a partially enlarged longitudinal sectional view schematically showing a recess formed in the measurement object, and FIG. 4 is an image diagram schematically showing a state where the surface of the measurement object in FIG. 3 is photographed. FIG. 5 is a gradation change graph showing an example in which the gradation value of each pixel is measured along the center line V of FIG.

  As shown in FIGS. 3 and 4, when the concave portion D is formed on the measurement object W, the concave portion image D ′ corresponding to the concave portion D of the image is photographed as an annular shadow. This shadow is generally elliptical. The recessed portion image D ′ has an annular dark portion and a bright portion inside the annular shape. Further, the outer side of the recessed portion image D ′ in the image is a bright portion.

  The inner and outer portions of the recessed portion image D ′ are bright portions because the peak at the substantially center where the gradation value in FIG. 5 is increasing is the lowest position DL, which is the lowest position of the recessed portion D in FIG. 5 corresponds to the flat part Ws of the measuring object W in FIG. 3, and these two positions are substantially horizontal, that is, This is because, when the tilt angle is approximately 0 °, the amount of light in the direction component (upward in FIG. 3) perpendicular to the surface of the measurement object W in the reflected light is increased.

  Further, as shown in FIG. 5, the annular dark portion of the recess image D ′ is more specifically increased after the gradation value is gradually decreased from the inside toward the outside. This is because the light quantity of the direction component (upward in FIG. 3) orthogonal to the surface of the measurement object W among the reflected light of the measurement object W increases or decreases depending on the inclination angle of each position. Therefore, it can be seen that the increase / decrease in the gradation value of the concave image D ′ corresponds to the inclination angle gradually.

  In the recessed part image extracting step S2, a binarized image is created by binarizing the image displayed in the light and shade obtained in the image obtaining step S1, and a portion corresponding to the recessed part image is selected from the binarized image. After that, the binarization process is canceled and the recessed portion image displayed in a shaded manner is acquired. This binarization processing is to convert the gradation value of each pixel of the grayscale display image to black if it is smaller than a predetermined threshold value, to convert it to white if it is larger than the predetermined threshold value, and to convert it into two gradations of black and white. As shown in FIG. 6, since the binarized concave image is displayed as an elliptical black ring, specifically, a black ring portion is extracted from the binarized image. Thereby, a recessed part image can be easily extracted from an image.

  In the image processing step S3, a smoothing process is performed on the concave image extracted in the concave image extraction step S2. This smoothing process is to remove the noise on the concave image using filters and reduce the fine gradation change to smooth the gradation change of the concave image. This filter is, for example, an average value filter (mediate filter) or a median filter (median filter). Further, in addition to the smoothing process, a general edge enhancement filter or the like may be used to correct defocusing or blurring of the concave image.

  In the maximum gradation acquisition step S4, the maximum gradation value Vmax and the position (X_Vmax, Y_Vmax) of the recess image D ′ are acquired. As shown in FIG. 7, first, the vertical axis py passing through the position where the horizontal width p of the concave image D ′ is divided into two half lengths p / 2 and the vertical width q of the concave image D ′ are two half. The position where the horizontal axis qx passing through the position divided into the length q / 2 intersects is specified as the center position C of the recessed portion image D ′.

  Next, the maximum value of the gradation values of each pixel in the central position C and its vicinity is acquired as the maximum gradation value Vmax, and the pixel position of the maximum gradation value Vmax is obtained as the position of the maximum gradation value ( X_Vmax, Y_Vmax). In this case, when there are a plurality of pixels having the maximum gradation value, the pixel having the shortest distance from the position of these pixels to the center position C is selected as the maximum gradation value. Select as a pixel. This is because the center position C of the recessed image D ′ tends to correspond to the pixel position of the maximum gradation value (see FIGS. 4 and 5).

  In the calculation step S5, the calculated value Depth of the recess depth is calculated using the maximum gradation value Vmax acquired in the maximum gradation acquisition step S4 and its position (X_Vmax, Y_Vmax). FIG. 8 is an explanatory diagram showing a calculation method of the calculated value of the recess depth. As shown in FIG. 8, the position (X_Vmax, Y_Vmax) of the maximum gradation value of the recess image is set to i = 0, the peripheral position of the recess image is set to i = w, and the interval between i = 0 and i = w is set. Assuming that Dep (i) is the amount of increase in the depth direction at an arbitrary position i, the calculated depth Depth of the concave portion is each position from the position of the maximum gradation value to the peripheral position of the concave image (i = 0 to w). The amount of increase in the depth direction corresponding to (Dep (1) to Dep (w)) can be added together.

  Here, the amount of increase in the depth direction corresponding to the arbitrary position i is Dep (i), the inclination angle of the tangent at the position of the concave portion corresponding to the arbitrary position i is θi, and the arbitrary position i and When the distance to the adjacent position i + 1 is Δi, the relational expression (2) is established.

  The relational expression (2) can be modified to obtain the depth increase amount Dep (i) at an arbitrary position i. The increase amount Dep (i) in the depth direction approximates to tan θi · Δi.

  When this equation (3) is substituted into the above equation (1), equation (4) is derived.

  Here, as shown in FIGS. 9 and 10, when the concave portion D is irradiated with light Light in a direction substantially perpendicular to the flat portion Ws of the measurement object W (downward in FIGS. 9 and 10), the concave portion D is obtained. At a position i that is a predetermined distance away from the lowest position DL, light is reflected in a predetermined direction. This reflected light is Ri, the vertical component (upward in FIG. 10) of this reflected light Ri is Riv, the tangent at this position i is t, and the inclination angle formed by this tangent t and the horizontal line h is θi. Then, the angle formed between the vertical component Riv of the reflected light and the tangent t is 90−θi because the angle formed between the vertical component Riv of the reflected light and the horizontal line h is 90 °.

  If the normal line orthogonal to the tangent line t is n, the angle between the normal component n and the normal line n of the reflected light is 90 °, and the angle between the normal line n and the tangent line t is 90 °. By subtracting an angle 90-θi formed by the vertical component Riv and the tangent t, θi is obtained.

  At this time, the angle θi formed between the vertical component Riv of the reflected light and the normal line n is an incident angle, and the angle formed between the reflected light Ri and the normal line n is a reflection angle. Therefore, the incident angle and the reflection angle are equal to each other. Is applied, the angle between the reflected light Ri and the normal n is θi. Therefore, the angle formed by the reflected light Ri and the vertical component Riv of the reflected light is 2θi.

  Accordingly, the relational expression (5) is established from the reflected light Ri, the vertical component Riv of the reflected light, and the angle 2θi formed by the reflected light Ri and the vertical component Riv of the reflected light.

  The relational expression (5) can be transformed into the expression (6).

  When this equation (6) is divided by 2, the inclination angle θi at an arbitrary position i can be obtained.

  When this equation (7) is substituted into the above equation (4), the following equation (8) is derived.

  Here, the light amount of the reflected light Ri at an arbitrary position i is the same as the light amount of the reflected light R0 at the lowest position DL of the recess D, and the light amount of the reflected light R0 is set as the maximum gradation value Vmax of the recess image D ′. You can get it.

  Further, the light amount of the vertical component Riv of the reflected light at an arbitrary position i can be acquired as the gradation value V (i) at the position of the concave image D ′ corresponding to the arbitrary position i of the concave part D.

  By substituting these equations (9) and (10) into the above equation (8), the following equation (11) is derived. Note that, from this equation (11), the inclination angle θi at an arbitrary position i of the recess D is equal to the gradation value V (i) at the position of the recess image D ′ corresponding to the arbitrary position i of the recess D and the recess image D. It can be seen that the calculation is performed using the ratio of 'to the maximum gradation value Vmax.

  Using the above equation (11), the calculated depth Depth of the recess is calculated. At this time, the maximum gradation value Vmax is the maximum gradation value Vmax acquired in the maximum gradation acquisition step S4, and the gradation value V (i) is the concave image D ′ acquired in the maximum gradation acquisition step S4. This is the gradation value of each pixel from the position of the maximum gradation value to the peripheral position. Note that the distance Δi is set to 1 assuming that calculation is performed pixel by pixel from the position of the maximum gradation value of the concave image D ′ to the peripheral position.

  As shown in FIG. 11, in this case, the calculated depth Depth of the concave portion is calculated for each of four different directions from the position of the maximum gradation value of the concave portion image D ′ to the peripheral position. In the illustrated example, the calculated values Depth (1), Depth (2), Depth (3), and Depth (4) of the four recess depths are calculated in the four directions of up, down, left, and right.

  Next, the calculated value Depth (1), Depth (2), Depth (3), Depth (4) of these four recess depths is set to the calculated value Depth of the recess depth in the recess image D ′. Select as (max).

  Finally, in the correction step S6, the calculated depth Depth (max) of the recess is corrected so as to approach the actual measurement value using the correlation with the actual measurement value. Specifically, as shown in FIG. 12, with respect to a plurality of recesses formed on the measurement object W, the horizontal axis indicates the actual measurement values actually measured using an instrument capable of measuring the recess depth, such as a confocal microscope. Taking (X axis), plotting (dotting points) on the vertical axis (Y axis) with the calculated value of the recess depth calculated in the above calculation step S5, creating a scatter diagram and drawing a regression line. An inclination a and an intercept b of the regression line are obtained, and a correlation formula (12) between the measured value Depth (act) and the calculated value Depth (max) of the recess depth is obtained.

  Using this correlation formula (12), the calculated value Depth (max) of the recess depth is corrected to obtain the corrected value Depth (amd) of the recess depth. The correction value Depth (amd) of the recess depth approximates to the actually measured value Depth (act) of the recess depth. For this reason, the calculated depth Depth (max) of the recess depth can be made closer to the actually measured value Depth (act).

  As described above, in the method for measuring the recess depth of the present embodiment, the calculated value Depth of the recess depth based on the gradation value from the coordinate position of the maximum gradation value of the recess image D ′ to the peripheral position in the calculation step S5. Since the gradation value of each pixel from the position of the maximum gradation value to the peripheral position is different even if the outer diameter, area, etc. of the recessed portion image D ′ are the same, the recessed portion image D ′ is calculated. Compared to the case where the depth of the recess is obtained from the correlation between the outer diameter and the area of ', the depth of the recess can be detected with high accuracy.

  In addition, the equation (11) used in the calculation step S5 indicates that the inclination angle θi at the arbitrary position i of the concave portion D is the gradation value V (i) at the position of the concave image D ′ corresponding to the arbitrary position i of the concave portion D. And the maximum gradation value Vmax of the recessed portion image D ′ is calculated, and therefore the calculated value of the recessed portion depth can be hardly affected by the brightness of the light light at the time of image acquisition. The reliability of the calculated value can be guaranteed.

  Further, in the calculation step S5, the calculated depth Depth (max) of the concave portion is the maximum value calculated in each of four different directions from the position of the maximum gradation value of the concave portion image D ′ to the peripheral position. The calculated value of the recessed portion depth calculated based on the gradation error of the recessed portion image D ′ caused by a foreign substance or the like can be automatically excluded, and the reliability of the calculated recessed portion depth can be further ensured.

[Inspection equipment]
Next, an inspection apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic perspective view schematically showing the inspection apparatus of the present embodiment. As shown in FIG. 2, the inspection apparatus 100 is disposed to face the XY stage 110 (positioning means) and the placement unit 111 of the XY stage 110 with a predetermined interval therebetween. It has an illumination device 120 (illuminating means), a camera 130 (imaging means) and a magnifying glass 140, and a personal computer 150 (calculating means) electrically connected to the camera 130.

  The XY stage 110 includes a flat placement portion 111 on which a measurement object W can be placed, such as a silicon substrate. The placement portion 111 is driven by a driving mechanism (not shown) in the front-rear direction and the left-right direction (see FIG. 2 is configured to be movable in the A direction and the B direction. Thereby, the measuring object W can be positioned.

  The illumination device 120 irradiates the mounting portion 111 with light that is substantially orthogonal to the mounting portion 111 of the XY stage 110, and the light source thereof is, for example, an LED (Light Emitting). Diode: light emitting diode). The camera 130 is configured to take a picture of the placement unit side of the XY stage 110 and acquire a grayscale image expressed in 256 gradations, and is a CCD camera, for example. The magnifying mirror 140 is configured to be able to magnify an incident image at a predetermined magnification, and is a microscope, for example. The personal computer 150 sequentially executes the concave portion image extraction step S2, the image processing step S3, the maximum gradation acquisition step S4, the calculation step S5, and the correction step S6 of the concave portion measurement method, and the concave portion depth calculated thereby. This is a device for judging whether the correction value Depth (amd) is good or not based on a predetermined threshold value.

  A magnifying glass 140 is connected to the photographing side (XY stage side in FIG. 2) of the camera 130, and the camera 130 acquires an image magnified by the magnifying glass 140. A lighting device 120 is connected to the side of the magnifier 140. The camera 130 and the personal computer 150 are electrically connected via a copper wire 160 (transfer means), and are configured to sequentially transfer images from the camera 130 to the personal computer 150.

  The recess depth measuring apparatus 100 configured as described above measures when the measurement object W is placed on the placing section 111 of the XY stage 110 and then irradiated with the light light from the lighting device 120. A light irradiation range S is formed on the surface of the object W, and in this state, when the image is taken by the camera 130, an image of an inner part of the light irradiation range S of the surface of the measurement object W is acquired. The image is transferred from the camera 130 to the personal computer 150.

  In the inspection apparatus 100 according to this embodiment, the concave portion image extraction step S2, the image processing step S3, and the maximum gradation acquisition step in the method of measuring the concave portion depth with respect to the image of the measurement object W using the personal computer 150. S4, the calculation step S5, and the correction step S6 are sequentially executed, and the quality of the calculated correction value Depth (amd) of the recess depth is determined based on a predetermined threshold value. This can be done in time, and thus product costs can be reduced.

  Further, the camera 130 and the personal computer 150 are electrically connected via the copper wire 160, and are configured to sequentially transfer images from the camera 130 to the personal computer 150. Compared to moving an image from the camera 130 to the personal computer 150 via a storage medium such as a digital versatile disc) or a flash memory, the image can be moved easily and in a short time. The speed of appearance inspection can be increased.

  It should be noted that the method for measuring the recess depth and the inspection apparatus according to the present embodiment are not limited to the illustrated examples described above, and various modifications can be made without departing from the scope of the present invention. is there. For example, the grayscale image acquired by the image acquisition step S1 of the concave depth measurement method of the present embodiment is expressed with 256 gradations, but may be 16 gradations or 65,536 gradations. .

  Further, the grayscale image acquired in the image acquisition step S1 of the concave depth measurement method of the present embodiment is grayscale, but may be RGB full color.

  Note that, in the calculation step S5 of the method for measuring the recess depth of the present embodiment, the calculated value Depth of the recess depth is calculated pixel by pixel from the position of the maximum gradation value of the recess image D ′ to the peripheral position. The calculation may be performed while skipping an arbitrary number of pixels, such as every other pixel or every two pixels.

  In the inspection apparatus of the present embodiment, the camera 130 and the personal computer 150 are electrically connected by the copper wire 160. However, it is only necessary to transfer an image from the camera 130 to the personal computer 150. The camera 130 and the personal computer 150 are connected by an optical fiber. They may be connected, or may be configured to transfer images from the camera 130 to the personal computer 150 by wireless, laser, infrared, or the like.

S1 ... Image acquisition step, S2 ... Concave image extraction step, S3 ... Image processing step, S4 ... Maximum gradation acquisition step, S5 ... Calculation step, S6 ... Correction step, W ... Measurement object, Ws ... Flat part, D ... Concave part, DL ... lowest position, D '... concave image, S ... light irradiation range, V ... center line, Vmax ... maximum gradation value, (X_Vmax, Y_Vmax) ... coordinates of maximum gradation value, p ... horizontal length, p / 2 ... Half length of horizontal width, py ... Vertical axis, q ... Vertical length, q / 2 ... Half length of vertical width, qx ... Horizontal axis, C ... Center position, i ... Arbitrary pixel, Dep (i ) ... Increase in depth direction, .theta.i ... tilt angle, .DELTA.i ... distance, R0, Ri ... reflected light, Riv ... vertical component of reflected light, t ... tangent, h ... horizontal line, n ... normal, Depth, Depth ( 1), Depth (2), Depth (3), Depth (4), Depth (max) ... concave Calculated value of depth, a ... slope, b ... intercept, Depth (act) ... measured value of recess depth, Depth (amd) ... corrected value of recess depth, 100 ... inspection device, 110 ... XY stage 111, placement unit, 120, illumination device, 130, camera, 140, magnifier, 150, personal computer, 160, copper wire, Light, light, A, B, direction

Claims (5)

  An image obtained by irradiating the measurement object with light in a direction substantially orthogonal to the measurement object on which the concave portion is formed and causing a shadow on the periphery of the concave portion is obtained in a shaded display. A method of measuring a depth of a recess having an image acquisition step, comprising a calculation step of calculating the depth of a recess based on a gradation value from approximately the center to the periphery of a portion corresponding to the recess of the image. A method for measuring the depth of the recess.   2. The concave portion depth according to claim 1, wherein in the calculating step, the concave portion depth is set to a maximum value calculated from at least two directions different from each other from a substantial center of a portion corresponding to the concave portion of the image. Measuring method.   3. The recess depth according to claim 1, further comprising a correction step of correcting the recess depth in the calculation step so as to approach the actual measurement value based on a correlation with the actual measurement value. Measuring method.   Positioning means provided with a placement portion on which a measurement object having a recess formed thereon can be placed, and a placement section that is opposed to the placement portion described above of the positioning means, with a predetermined interval between them. An inspection apparatus comprising: an illuminating unit that irradiates light toward the mounting unit; and an imaging unit that captures the image of the mounting unit side of the positioning unit and acquires a gray-scaled image. An inspection apparatus comprising: a calculation unit that executes at least the calculation step of the method for measuring a recess depth according to any one of claims 1 to 3.   The inspection apparatus according to claim 4, further comprising transfer means capable of transferring the grayscale image from the imaging means to the calculation means.