JP6697328B2 - Wafer detecting method for detecting outer peripheral position of wafer and processing apparatus capable of detecting outer peripheral position of wafer - Google Patents

Description

  The present invention relates to a wafer detection method for detecting the outer peripheral position of a wafer and a processing apparatus capable of detecting the outer peripheral position of the wafer.

  In grinding a wafer in a semiconductor manufacturing process, for example, when a wafer whose outer peripheral portion is rounded and chamfered is ground and thinned, the outer peripheral portion of the wafer is formed in a sharp edge shape toward the outer peripheral portion. Then, the sharp edge causes the strength of the outer periphery of the wafer to decrease, which causes a problem that the wafer is likely to be broken when an impact is applied to the outer periphery of the wafer, that is, a so-called sharp edge of the wafer. In order to prevent wafer cracking due to this sharp edge, before grinding and thinning the wafer, the chamfered portion on the outer periphery of the wafer is trimmed into a circular shape by cutting and removed, so that the sharpened edge on the wafer after thinning There is a wafer processing method for preventing the formation (for example, refer to Patent Document 1).

  In addition, there is an apparatus for performing a removal process on a wafer with a cutting blade as described in Patent Document 1 (see, for example, Patent Document 2). In such an apparatus, in order to prevent foreign matter from adhering to the wafer, for example, the wafer is processed while being held by a holding unit having an annular holding surface that holds only the outer peripheral portion of the back surface of the wafer. ..

  Then, the position where the cutting blade is cut into the wafer is determined by detecting the outer peripheral edge from a captured image formed by capturing an image of the outer peripheral edge region of the wafer by the image capturing unit, as disclosed in Patent Document 3, for example. Therefore, a position radially inward from the outer peripheral edge of the wafer detected from this captured image is cut by a cutting blade in the circumferential direction.

JP, 2000-173961, A JP, 2005-023239, A JP, 2013-084755, A

  However, if the amount of light at the time of imaging the wafer or the image processing of the formed captured image is not appropriate, a position different from the actual outer peripheral edge position may be detected as the outer peripheral edge of the wafer. Therefore, when detecting the outer peripheral edge position of the wafer, there is a problem of reducing the risk of detecting a position different from the actual outer peripheral edge position as the outer peripheral edge of the wafer.

  The present invention for solving the above problems, a holding table having a holding surface for holding the wafer, a light irradiator for irradiating the wafer held by the holding table with light, and a wafer held by the holding table. An image pickup means having a camera for picking up an image to form a picked-up image, and a wafer detection method for detecting the outer peripheral position of the wafer using an apparatus provided with, a holding step of holding the wafer on the holding table, After performing the holding step, the wafer held by the holding table is irradiated with light amounts of a plurality of layers from the light irradiator and is imaged by the camera to form a plurality of imaged images including the outer peripheral edge of the wafer. Binarization for forming a binarized image by performing the forming step and the picked-up image forming step, and then binarizing the picked-up images picked up for each of the light amounts of the plurality of layers at slice levels of the plurality of layers. Step, a wafer outer peripheral position detecting step of detecting and recording the boundary between white pixels and black pixels in the binarized image formed in the binarizing step as a coordinate position of the outer peripheral edge of the wafer, and the wafer outer peripheral position The wafer detection method comprises: a light amount slice level setting step of setting, as optimum values, a light amount and a slice level at coordinate positions where the position coordinates recorded in the detection step are most dense.

  When the light amount and the slice level at the coordinate position where the position coordinates recorded in the wafer outer peripheral position detection step are most dense reach each of a plurality of layers, the light amount slice level is set with the median value of each of the plurality of layers as an optimum value. It is preferable to set in steps.

  Further, the present invention for solving the above-mentioned problems is held by a holding table having a holding surface for holding a wafer, a light irradiator for irradiating the wafer held by the holding table with light, and the holding table. A processing apparatus comprising: an image pickup unit having a camera for picking up an image of a wafer and forming a picked-up image; a processing unit for processing a wafer held by the holding table; and a control unit for controlling at least the processing unit. Therefore, the control means irradiates the wafer held by the holding table with light amounts of a plurality of layers from the light irradiator and forms a plurality of picked-up images including the outer peripheral edge of the wafer formed by picking up an image with the camera. A picked-up image forming unit, a binarization processing unit that binarizes the picked-up images formed for each of the light amounts of a plurality of layers at slice levels of a plurality of layers to form a binarized image, and the binarization The boundary between the white pixel and the black pixel in the binarized image formed by the processing unit is detected as a coordinate position of the outer peripheral edge of the wafer and is recorded as a wafer outer peripheral position detection unit, and is recorded by the wafer outer peripheral position detection unit. The processing apparatus includes: a light amount slice level setting unit that sets a light amount and a slice level at coordinate positions where position coordinates are most densely set as optimum values.

  When the light quantity and the slice level at the coordinate position where the position coordinates recorded by the wafer outer circumference position detection section are most concentrated reach each of a plurality of layers, the light quantity slice level is set with the respective median values of the plurality of layers as the optimum values. It is preferable to set in part.

  A wafer detection method according to the present invention is a method for forming a captured image in which a wafer held by a holding table is irradiated with a plurality of levels of light from a light irradiator and a camera captures an image to form a plurality of captured images including an outer peripheral edge of the wafer. After performing the step and the captured image forming step, a binarizing step of forming a binarized image by binarizing the captured images captured for each of the light amounts of the plurality of layers at slice levels of a plurality of layers, respectively. After performing the wafer outer peripheral position detection step of detecting and recording the boundary between the white pixel and the black pixel in the binarized image formed as the coordinate position of the outer peripheral edge of the wafer, the wafer outer peripheral position detection step By performing the light amount slice level setting step of setting the light amount and the slice level of the coordinate position where the position coordinates recorded in the most densely as the optimum value, it is possible to obtain the optimum light amount obtained in the light amount slice level setting step. It is possible to binarize the image of the wafer at the optimum slice level obtained in the step of imaging the wafer with the camera and setting the slice level of the light quantity, and detect the position different from the actual outer edge position as the outer edge of the wafer. It is possible to reduce the risk of being lost.

It is sectional drawing which shows the state which hold | maintains a wafer by the holding table in a holding step. It is sectional drawing which shows the state which is imaging the wafer by the imaging means. FIG. 6 is a plan view showing a plurality of picked-up images having different irradiation light amounts including the outer peripheral edge of the wafer formed by the camera and formed by the picked-up image forming unit, in an overlapping manner. It is explanatory drawing which binarizes a plurality of picked-up images formed by a picked-up image forming unit with different irradiation light amounts including the outer peripheral edge of the wafer at slice levels of a plurality of layers to form a binarized image. It is explanatory drawing which shows the binarized image divided into the white pixel and the black pixel and displayed on the virtual output screen in a wafer outer peripheral position detection step. It is the plot figure which detected the coordinate position of the outer peripheral edge of the wafer in the wafer outer peripheral position detection step, and plotted it on the X-axis Y-axis coordinate system. It is explanatory drawing which shows the binarized image divided and displayed into the white pixel and the black pixel on the virtual output screen in a wafer outer peripheral position detection step. It is the plot figure which detected the coordinate position of the outer peripheral edge of the wafer in the wafer outer peripheral position detection step, and plotted it on the X-axis Y-axis coordinate system. It is explanatory drawing which binarizes the picked-up image containing the outer peripheral edge of the wafer imaged by the optimal irradiation light quantity by the optimal slice level, and forms a binarized image. It is explanatory drawing which shows the state which divided the binarized image binarized by the optimal slice level into the white pixel and the black pixel, and was displayed on a virtual output screen. It is sectional drawing which shows the state which trims the outer periphery of a wafer with a processing means.

  Hereinafter, a method of detecting the outer peripheral position of the wafer by using the processing apparatus 1 according to the present invention will be described.

1 Setting of Optimum Conditions (1) Holding Step The wafer W shown in FIG. 1 is a disk-shaped semiconductor wafer (for example, a silicon wafer), and its surface Wa has a device region Wa1 and an outer peripheral region surrounding the device region Wa1. Wa2 and are provided. The device region Wa1 is divided into a plurality of regions by the planned dividing lines S arranged in a grid pattern, and devices D such as ICs are formed in the respective regions. The outer peripheral edge Wd of the wafer W is chamfered to have a substantially arcuate cross section.

  The processing apparatus 1 shown in FIG. 1 is an apparatus that performs a cutting process on the wafer W and that can detect the outer peripheral position of the wafer W. The holding table 30 which is provided in the processing apparatus 1 and holds the wafer W shown in FIG. 1 by suction is formed on the outer periphery of the table body 300 so that an annular holding portion 301 projects in the + Z direction. A recess is formed in the center so as to be surrounded. The upper surface of the annular holding portion 301 is an annular holding surface 301a that sucks and holds the outer peripheral portion of the back surface Wb of the wafer W placed on the holding table 30. An annular groove or a suction hole (not shown) is formed in the annular holding surface 301a, and the suction source 302 communicates with the annular groove or the suction hole. The holding table 30 can rotate at least about the Z-axis direction.

  In the holding step, after the wafer W is positioned so that the center of the wafer W is located at the rotation center of the holding table 30, the wafer W is placed on the annular holding surface 301a of the holding table 30 so that the front surface Wa of the wafer W faces upward. To do. Then, a suction source (not shown) communicating with the annular holding surface 301a is operated to suck the outer peripheral portion of the back surface Wb of the wafer W on the annular holding surface 301a of the holding table 30 to suck and hold the wafer W.

(2) Imaging Image Forming Step The imaging means 2 shown in FIG. 2 included in the processing apparatus 1 includes a light irradiator 20 that irradiates the wafer W held by the holding table 30 with light, and a wafer W held by the holding table 30. And a camera 21 that captures the image and forms a captured image. The light irradiator 20 can adjust the amount of light emitted from the light source 200 (for example, an LED or a xenon lamp) by the voltage adjuster 201. An optical fiber 202 is connected to the light irradiator 20, and the light emitted from the light source 200 reaches the inside of the camera 21 through the inside of the optical fiber 202. The camera 21 includes a case 210 that is shielded from external light, and a half mirror 211 that is disposed in the case 210 and reflects light emitted from the light irradiator 20 and incident through the optical fiber 202 downward to change its direction. And an objective lens 212 disposed below the half mirror 211 to receive the light reflected by the half mirror 211, and an image sensor 213 disposed above the half mirror 211. The half mirror 211 has a function of guiding the light emitted from the light irradiator 20 and incident through the optical fiber 202 to the wafer W, and a function of transmitting the reflected light from the wafer W and guiding it to the image sensor 213. .. The optical axis of the objective lens 212 is orthogonal to the front surface Wa of the wafer W held by the holding table 30. The image sensor 213 receives the reflected light from the wafer W and outputs a corresponding image. The image pickup means 2 may be vertically movable and movable in the horizontal plane direction. The camera 21 is connected to a control unit 9 including a CPU and a storage element such as a memory.

  In the captured image forming step, as shown in FIG. 2, the wafer W is positioned below the camera 21 so that the outer peripheral edge Wd of the wafer W is set within the imaging region of the camera 21. In that state, when the predetermined voltage adjusted by the voltage adjuster 201 is applied to the light source 200, the light source 200 emits light of a light amount corresponding to the applied voltage. The light emitted from the light source 200 passes through the optical fiber 202, is reflected by the half mirror 211, and is irradiated onto the wafer W via the objective lens 212. Then, the reflected light from the wafer W is condensed by the objective lens 212 and focused on the image sensor 213, so that the camera 21 forms a captured image including the outer peripheral edge Wd of the wafer W.

  The control unit 9 includes a picked-up image forming section 90 that forms a plurality of picked-up images including the outer peripheral edge Wd of the wafer picked up by the camera 21 by irradiating the light amounts of a plurality of layers, and the picked-up image forming section 90 has a voltage. The voltage applied to the light source 200 is adjusted by the adjuster 201, and the irradiation light amount of the light irradiator 20 with respect to the wafer W is changed by 1% from 1% to 100%, for example, as shown in FIG. Accordingly, a captured image G1, a captured image G2, ..., A captured image Gk, ..., A captured image Gm (m is 100 in the present embodiment) including the outer peripheral edge Wd of the wafer W and having different irradiation light amounts are formed. To do. In FIG. 3, the formed captured image G1, captured image G2, ... Captured image Gk, ... Note that the image pickup image G1, the image pickup image G2, ..., The image pickup image Gk, ..., The image pickup for forming the image pickup image Gm is performed by fixing the height position of the camera 21 and the position on the X-axis Y-axis plane. To do. In the formed 100 captured images G1, captured images G2, ..., Captured image Gk, ..., Captured image Gm, a part of the outer peripheral edge of the wafer W and the background portion (the annular holding surface of the holding table 30) are shown. (A part of 301a) is displayed. The captured image G1, the captured image G2, ..., The captured image Gk ..., The captured image Gm are transferred from the camera 21 to the captured image forming unit 90 of the control unit 9.

(3) Binarization Step As shown in FIG. 2, the control means 9 binarizes the picked-up images formed for each of the light amounts of the plurality of layers at slice levels of the plurality of layers to form a binarized image. The binarization processing unit 91 is provided. The picked-up image G1, the picked-up image G2, ..., The picked-up image Gk, ..., The picked-up image Gm shown in FIG. 3 formed by the picked-up image forming unit 90 are transferred to the binarization processing unit 91.

The binarization processing unit 91 sets the captured image G1, the captured image G2, ..., The captured image Gk, ..., The captured image Gm captured for each of the light amounts of the plurality of layers to the slice level (threshold) of the plurality of layers. And binarize each to form a plurality of binarized images. That is, the binarization processing unit 91, for example, a plurality of captured images G1, captured images G2, ... For example, a pixel having a luminance value lower than the slice level is set to 0, and a pixel having a luminance value higher than the slice level is set to 255, and the image is converted into a binary image. As shown in FIG. 4, with respect to the captured image G1, the value of the binarized slice level is changed by 1 in the range of 0 to 255, and the binarization processing is performed using each slice level as a reference. The binarized images G1 ₀ , G1 _1, ..., G1 _j , ... Binary image G1 _n (n is 255) are formed. In the binarized image G1 ₀ , the binarized image G1 ₁ ..., The binarized image G1 _j , ... The binarized image G1 _n , the pixels having the brightness value less than the set slice level are imaged. Pixels having a brightness value equal to or higher than the set slice level are displayed in white in the image. The binarization processing unit 91 performs the same processing on the captured images G2 to Gm having different light amounts. In this way, a total of 25,600 binarized images are formed by forming 256 binarized images for each captured image.

(4) Wafer outer peripheral position detection step As shown in FIG. 2, the control means 9 sets the coordinates of the outer peripheral edge of the wafer at the boundary between the white pixel and the black pixel in the binarized image formed by the binarization processing unit 91. A wafer outer peripheral position detection unit 92 for detecting and recording the position is provided. Wafer peripheral position detector 92 is divided, for example, a binary image G1 ₀ for the captured image G1, as shown in FIG. 5, for example, a white pixel and a black pixel on the virtual output screen B of resolution 1600 × 1200 Then, the coordinates (x, y) on the X-axis and Y-axis plane of the boundary between the white pixel and the black pixel are detected as the coordinate position of the outer peripheral edge Wd of the wafer W. Then, each detected coordinate is plotted and recorded as a black dot on the X-axis Y-axis coordinate system shown in FIG. As shown in FIG. 6, each detected coordinate is plotted in an arc shape that approximates the arc of the wafer W on the X-axis Y-axis coordinate system.

Similarly, from the remaining 255 binarized images G1 ₁ , G1 _2, ..., G1 _j , ... Binarized image G1 _{n with} respect to the captured image G1 shown in FIG. The coordinate position is detected, and each acquired coordinate is further plotted and recorded on the X-axis and Y-axis coordinate system shown in FIG. Thus, the wafer outer peripheral position detection unit 92 determines the coordinate position of the outer peripheral edge Wd of the wafer W based on the 256 binarized images G1 ₀ to G1 _n with respect to the captured image G1 as the X-axis and Y-axis coordinates. A plot diagram E1 plotted on the system is created.

  Further, the wafer outer peripheral position detection unit 92 also plots each of the 256 binarized images for the remaining captured images G2 to Gm in the same manner as creating the plot E1 for the captured image G1. Plot it on the diagram. Therefore, in the present embodiment, the wafer outer peripheral position detection unit 92 creates a total of 100 plot diagrams in which the coordinate positions of the outer peripheral edge Wd of the wafer W are plotted in the X-axis Y-axis coordinate system.

  The wafer outer peripheral position detection step may be performed as follows, for example, in addition to the above-described steps. First, all the binarized images acquired in the binarization step are transmitted from the binarization processing unit 91 shown in FIG. 2 to the wafer outer peripheral position detection unit 92 provided in the control means 9.

Wafer outer peripheral position detector 92, for example a binary image G1 ₀ for the captured image G1 shown in FIG. 4, as shown in FIG. 7, for example, a white pixel and black in a virtual output screen B of resolution 1600 × 1200 It is divided into pixels and displayed. Further, on the virtual output screen B, sets the straight line L3 shown by the broken line extending in the X axis direction is a Y-coordinate is constant, the boundaries and the broken line between the white pixel and black pixel of the binarized image G1 ₀ area The coordinates of the intersection (x, y) with L3 are detected as the coordinate position of the outer peripheral edge Wd of the wafer W, and as shown in FIG. 8, one acquired coordinate is plotted on the X-axis Y-axis coordinate system ( (Black dots in FIG. 8) are recorded.

Similarly, the wafer outer peripheral position detection unit 92 determines that each of the remaining 255 binarized images G1 ₁ , G1 _2, ..., G1 _j , ... _Binarized image G1 _n for the captured image G1 is binarized. The coordinates of the intersection (x, y) of the boundary between the white pixel and the black pixel in the digitized image area and the broken line L3 are respectively detected as the coordinate position of the outer peripheral edge Wd of the wafer W, and shown in FIG. In this way, each acquired coordinate is further plotted and recorded on the X-axis Y-axis coordinate system. That is, each one point on the same Y coordinate in the binarized image G1 ₁ to the binarized image G1 _n is plotted and stored. Then, the wafer outer peripheral position detection unit 92 determines the coordinate position of the outer peripheral edge Wd of the wafer W based on the 256 binarized images G1 ₀ to G1 _n with respect to the captured image G1 in the X-axis and Y-axis coordinate systems. A plot diagram F1 plotted in FIG. As shown in FIG. 8, on the X-axis Y-axis coordinate system of the plot F1, 256 coordinates detected on the same Y coordinate are linearly plotted in the X-axis direction. A straight line extending in the Y-axis direction having a constant X coordinate is set on the virtual output screen B, and white in each binarized image region in the binarized image G1 ₀ to the binarized image G1 _n . The intersections (x, y) of the boundary between the pixel and the black pixel and the straight line extending parallel to the Y-axis direction may be plotted and stored.

  Further, the wafer outer peripheral position detection unit 92 also determines the coordinate position of the outer peripheral edge Wd of the wafer W for the binarized images of the captured images G2 to Gm in the X-axis Y-axis coordinate system, as in the case of creating the plot F1. Create a plot that is plotted in. Therefore, in the present embodiment, the wafer outer peripheral position detection unit 92 creates a total of 100 plot diagrams in which the coordinate positions of the outer peripheral edge Wd of the wafer W are plotted in the X-axis Y-axis coordinate system.

(5) Light amount slice level setting step As shown in FIG. 2, the control means 9 sets the light amount and the slice level at the coordinate position where the position coordinates recorded by the wafer outer peripheral position detection unit 92 are most dense as an optimum value. A light quantity slice level setting unit 93 is provided. First, a total of 100 plot diagrams including the plot diagram E1 shown in FIG. 6 is transferred from the wafer outer peripheral position detection unit 92 to the light quantity slice level setting unit 93. The light quantity slice level setting unit 93 specifies, for example, the coordinates at which the position coordinates indicated by the black dots in the plot E1 shown in FIG. 6 are most dense, and the binary values used when plotting the coordinates within this region. The binarized image is specified from the binarized image G1 ₀ to the binarized image G1 _n . Further, the light quantity slice level setting unit 93 specifies the slice level when the specified binarized image is formed from the specified binarized image. For example, when the identified binarized image is one G1 _j (for example, j is 140), the identified slice level is also the slice level j (for example, slice level 140), but the identified binary value is When there are three binarized images such as the binarized image G1 _j−1 , the binarized image G1 _j , and the binarized image G1 _{j + 1} , the specified slice level is also the slice level (j−1), The slice level is j, the slice level (j + 1), that is, the slice level 139, the slice level 140, and the slice level 141.

  The light quantity slice level setting unit 93 similarly specifies the slice level for the remaining 99 plot diagrams. For example, when there is only one slice level j (for example, slice level 140) specified from all plots, the slice level 140 is determined as the optimum value. The slice level specified from all the plots extends across three, such as slice level (j−1), slice level j, and slice level (j + 1), that is, slice level 139, slice level 140, and slice level 141. In this case, the value having the middle value among the three slice levels, that is, the slice level 140 that is the median value is finally determined as the optimum value.

After determining the slice level 140 as the optimum value, the light quantity slice level setting unit 93 determines the optimum value of the irradiation light quantity for the wafer W from the light irradiator 20 shown in FIG. For example, 100 plot diagrams including the plot diagram E1 are each converted into a plot diagram composed only of plots based on the binarized image formed at the slice level 140. Further, the converted plots are displayed by superimposing them on the same plane with the X-axis and the Y-axis of the respective plots aligned with each other, and output, for example, to create a biplot. The light intensity slice level setting unit 93 specifies, for example, a region where the position coordinates are most dense from the biplot diagram, and the binarized image used when plotting each coordinate in this region is 100 binary images. It is specified from the binarized image G1 ₁₄₀ , the binarized image G2 ₁₄₀ , ..., The binarized image Gm ₁₄₀ . Further, the light quantity slice level setting unit 93 specifies the captured image of the specified binarized image before binarization from the specified binarized image. For example, when only one specified captured image is taken and the one is imaged with the irradiation light amount of 55%, the optimum irradiation light amount of the specified light irradiator 20 with respect to the wafer W is also 55%. Becomes For example, when there are three specified captured images and these three images are respectively captured with the irradiation light amounts of 54%, 55%, and 56%, the value is the middle among the three irradiation light amounts. The value, that is, the irradiation light amount of 55% which is the median value is finally determined as the optimum value. It should be noted that instead of the 100 total plots in which the coordinate position of the outer peripheral edge Wd of the wafer W including the plot E1 shown in FIG. 6 is plotted in the X-axis Y-axis coordinate system, the total including the plot F1 shown in FIG. The optimal values of the slice level and the irradiation light amount may be determined in the same manner as described above using the 100 plots. In this case, a part of the outer peripheral edge in the binarized image may be used, so that the time required for the process of obtaining the optimum condition can be shortened.

2 After performing the detection of the outer peripheral position of the wafer and the wafer processing light quantity slice level setting step, the light quantity slice level setting unit 93 finally uses the slice level 140 and the irradiation light quantity 55% determined as optimum values, A cutting process for trimming the wafer W into a circular shape is performed by the processing device 1.

  First, as shown in FIG. 2, the wafer W is positioned below the camera 21 so that the outer peripheral edge Wd of the wafer W is set within the imaging area of the camera 21. Then, the control unit 9 reads the optimum condition stored in the light quantity slice level setting unit 93, adjusts the voltage applied to the light source 200 by the voltage adjuster 201, and emits light from the light irradiator 20 at an irradiation light quantity of 55%. The wafer W is irradiated to form a captured image G55 including the outer peripheral edge Wd of the wafer W shown in FIG.

The formed captured image G55 is transferred from the camera 21 shown in FIG. 2 to the control unit 9 and binarized by the binarization processing unit 91 of the control unit 9 at the slice level 140, so that the binary image shown in FIG. A binarized image G55 ₁₄₀ is formed. The binarized image G55 ₁₄₀ is transferred from the binarization processing unit 91 to the wafer outer peripheral position detection unit 92, and the wafer outer peripheral position detection unit 92 displays the binarized image G55 ₁₄₀ as shown in FIG. Each pixel is displayed by dividing it into white pixels and black pixels on a virtual output screen B of × 1200, and each coordinate on the X-axis Y-axis plane of the boundary between the white pixels and the black pixels in the binarized image G55 ₁₄₀ area. (X, y) are successively detected as coordinate positions of the outer peripheral edge Wd of the wafer W.

  Thus, in the stage of setting the optimum conditions, the conditions of the light amount and slice level for surely detecting the outer peripheral edge of the wafer W are obtained, and under the conditions, the wafer W to be actually processed is imaged. By detecting the outer peripheral edge Wd, it is possible to reduce the risk of detecting a position different from the actual outer peripheral edge position as the outer peripheral edge Wd of the wafer W.

After the wafer outer peripheral position detection unit 92 detects the coordinate position of the outer peripheral edge Wd of the wafer W, the wafer W held on the holding table 30 is positioned immediately below the processing means 6 provided in the processing apparatus 1 shown in FIG. Be done. As shown in FIG. 11, the processing means 6 for processing the wafer W held on the holding table 30 is a cutting means, and has a spindle 60 whose axial direction is the Y-axis direction, and a motor 62 which rotationally drives the spindle 60. The cutting blade 63 is attached to the tip of the spindle 60, and the cutting blade 63 also rotates at high speed as the motor 62 drives the spindle 60 to rotate. Further, the processing means 6 is moved in the Y-axis direction on the basis of the coordinate position of the outer peripheral edge Wd of the wafer W detected by the wafer outer peripheral position detecting section 92 from the binarized image G55 _140, and the detected outer peripheral edge Wd of the wafer W is detected. The cutting blade 63 is positioned at a position radially inward of the cutting blade 63. For example, the cutting blade 63 is positioned such that about ⅔ of the end surface of the cutting blade 63 contacts the outer peripheral region Wa2 of the wafer W including the outer peripheral edge Wd of the wafer W.

  Then, the motor 62 rotates the spindle 60 at a high speed in the counterclockwise direction when viewed from the + Y direction side, thereby rotating the blade 63 fixed to the spindle 60 at a high speed in the counterclockwise direction when viewed from the + Y direction side. Further, the processing means 6 descends in the −Z direction, and the cutting blade 63 is cut from the front surface Wa of the wafer W by a predetermined depth. The cutting depth of the cutting blade 63 is determined, for example, based on the grinding amount of the wafer W in the grinding process performed after the trimming process of the wafer W. After the cutting blade 63 is cut and fed to a predetermined height position, the holding table 30 is continuously rotated at high speed in the clockwise direction when viewed from the + Y direction side, and the holding table 30 is viewed in the counterclockwise direction when viewed from the + Z direction side. By rotating the wafer W by 360 degrees, the entire outer peripheral edge Wd of the wafer W is cut and trimmed. For other wafers W, the outer peripheral edge Wd is detected and trimmed under the same set conditions.

  Thus, at the stage of setting the optimum conditions, the conditions of the light amount and the slice level for surely detecting the outer peripheral edge Wd of the wafer W are obtained, and under that condition, the wafer W to be actually processed is imaged. Since the outer peripheral edge Wd is detected and the blade 63 is cut based on the position, the desired position can be cut.

  The wafer detection method for detecting the outer peripheral position of the wafer according to the present invention is not limited to the above embodiment. For example, the light amount of the light with which the wafer W is irradiated and the slice level hierarchy at the time of binarization are not limited to the example of the present embodiment.

1: processing device 30: holding table 300: table body 301: annular holding portion 301a: annular holding surface 302: suction source 2: imaging means 20: light irradiator 200: light source 201: voltage adjuster 202: optical fiber 21: camera 210 : Case 211: Half mirror 212: Objective lens 213: Imaging device 6: Processing means 60: Spindle 62: Motor 63: Cutting blade 9: Control means 90: Captured image forming section 91: Binarization processing section 92: Wafer outer peripheral position Detection unit 93: Light intensity slice level setting unit W: Wafer Wa: Front surface of wafer Wb: Back surface of wafer Wa1: Device area Wa2: Outer peripheral area S: Divided line D: Device Wd: Outer peripheral edge

Claims (4)

A holding table having a holding surface for holding the wafer; a light irradiator for irradiating the wafer held by the holding table with light; and a camera for imaging the wafer held by the holding table and forming a picked-up image. A method of detecting a wafer, which detects an outer peripheral position of a wafer by using an apparatus including the image pickup means,
A holding step of holding the wafer on the holding table;
After performing the holding step, the wafer held by the holding table is irradiated with light amounts of a plurality of layers from the light irradiator and is imaged by the camera to form a plurality of imaged images including the outer peripheral edge of the wafer. A forming step,
After performing the captured image forming step, a binarization step of forming a binarized image by binarizing the captured images captured for each of the light amounts of a plurality of layers at slice levels of a plurality of layers, respectively.
A wafer outer peripheral position detecting step of detecting and recording a boundary between a white pixel and a black pixel in the binarized image formed in the binarizing step as a coordinate position of an outer peripheral edge of the wafer,
A wafer detection method comprising: a light quantity slice level setting step of setting a light quantity at a coordinate position where the position coordinates recorded in the wafer outer peripheral position detection step are most dense and a slice level as optimum values.   When the light amount and the slice level at the coordinate position where the position coordinates recorded in the wafer outer peripheral position detection step are most dense reach each of a plurality of layers, the light amount slice level is set with the median value of each of the plurality of layers as an optimum value. The method for detecting a wafer according to claim 1, wherein the method is set in steps. A holding table having a holding surface for holding the wafer; a light irradiator for irradiating the wafer held by the holding table with light; and a camera for imaging the wafer held by the holding table and forming a picked-up image. And a processing unit that processes the wafer held by the holding table, and a control unit that controls at least the processing unit.
The control means is
A picked-up image forming unit that forms a plurality of picked-up images including the outer peripheral edge of the wafer formed by irradiating the wafers held by the holding table with light quantities of a plurality of layers from the light irradiator and picked up by the camera,
A binarization processing unit that binarizes the captured images formed for each of the light amounts of a plurality of layers at slice levels of a plurality of layers to form a binarized image,
A wafer outer peripheral position detection unit that detects and records a boundary between a white pixel and a black pixel in the binarized image formed by the binarization processing unit as a coordinate position of an outer peripheral edge of the wafer,
A processing apparatus comprising: a light amount slice level setting unit that sets a light amount at a coordinate position where the position coordinates recorded by the wafer outer peripheral position detection unit are most dense and a slice level as optimum values.   When the light quantity and the slice level at the coordinate position where the position coordinates recorded by the wafer outer circumference position detection section are most concentrated reach each of a plurality of layers, the light quantity slice level is set with the respective median values of the plurality of layers as the optimum values. The wafer processing apparatus according to claim 3, wherein the wafer processing apparatus is set by a unit.

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