JP2017219364A - Wafer detection method for detecting peripheral position of wafer and processing device capable of detecting peripheral position of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a position that actually is not a peripheral edge position from being detected as a peripheral edge when detecting the peripheral edge position of a wafer.SOLUTION: Provided is a wafer detection method comprising: a step for holding a wafer W with a table 30; an imaged image formation step for irradiating the wafer W held by the table 30 with a quantity of light in a plurality of layers from a light irradiator 20 and imaging it with a camera 21, and forming a plurality of imaged images that include a peripheral edge Wd of the wafer W; a binarization step for binarizing each of imaged images having been imaged for each light quantity in the plurality of layers at a slice level in a plurality of layers and forming a binary image; a peripheral wafer position detection step for detecting a boundary between a white pixel and a black pixel in the binary image formed in the binarization step as the coordinate position of peripheral edge Wd of the wafer W; and a light quantity slice level setting step for setting the light quantity and slice level at a coordinate position where there is the largest mass of position coordinates recorded in the peripheral wafer position detection step as optimum values.SELECTED DRAWING: Figure 2

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 chamfered is rounded and thinned, the outer peripheral portion of the wafer is formed in a sharp edge shape toward the outer peripheral portion. Further, since the strength of the outer periphery of the wafer is lowered due to the sharp edge, there is a problem that the wafer is easily broken when an impact is applied to the outer periphery of the wafer, that is, a so-called sharp edge problem of the wafer. In order to prevent the wafer from being cracked by this sharp edge, the chamfered portion of the outer periphery of the wafer is trimmed and removed into a circular shape by cutting or the like before grinding and thinning the wafer, so that the sharpened edge is removed from the thinned wafer. There is a wafer processing method that prevents the wafer from being formed (see, for example, Patent Document 1).

  Further, there is an apparatus for performing removal processing as described in Patent Document 1 on a wafer with a cutting blade (see, for example, Patent Document 2). In such an apparatus, in order to prevent foreign matters 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. .

  The position at which the cutting blade is cut into the wafer is determined by detecting the outer periphery from the captured image formed by imaging the outer periphery region of the wafer with the imaging means, as disclosed in Patent Document 3, for example. A position radially inward from the outer peripheral edge of the wafer detected from the captured image is cut in the circumferential direction by a cutting blade.

JP 2000-173961 A Japanese Patent Laying-Open No. 2015-023239 JP2013-084755A

  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 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 possibility 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 includes a holding table having a holding surface for holding a wafer, a light irradiator for irradiating light to the wafer held by the holding table, and a wafer held by the holding table. A wafer detection method for detecting an outer peripheral position of a wafer using an apparatus provided with an imaging means having a camera for imaging and forming a captured image, the holding step for holding the wafer on the holding table; After carrying out the holding step, a captured image that irradiates the wafer held by the holding table with a plurality of levels of light from the light irradiator and picks up images with the camera to form a plurality of picked-up images including the outer peripheral edge of the wafer After performing the formation step and the captured image formation step, the captured image captured for each light quantity of the plurality of layers is binarized at each slice level of the plurality of layers. A binarization step for forming a binarized image, and a wafer outer periphery for detecting and recording a boundary between a white pixel and a black pixel in the binarized image formed in the binarization step as a coordinate position of the outer peripheral edge of the wafer A wafer detection method comprising: a position detection step; and a light quantity slice level setting step for setting the light quantity and slice level of coordinate positions where the position coordinates recorded in the wafer outer periphery position detection step are most densely set as optimum values. is there.

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

  In addition, the present invention for solving the above problems is a holding table having a holding surface for holding a wafer, a light irradiator for irradiating light to the wafer held by the holding table, and the holding table. A processing apparatus comprising: an imaging unit having a camera that images a wafer and forms a captured image; 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 unit forms a plurality of captured images including the outer peripheral edge of the wafer formed by irradiating the wafer held by the holding table with a plurality of levels of light from the light irradiator and imaging the wafer. A binarization processing unit that binarizes the captured image formed for each light quantity of a plurality of layers at a slice level of the plurality of layers to form a binarized image, and the binarization A wafer outer periphery position detection unit that detects and records a boundary between white pixels and black pixels in the binarized image formed by the processing unit as a coordinate position of the outer periphery of the wafer, and recorded by the wafer outer periphery position detection unit The processing apparatus includes a light amount slice level setting unit that sets the light amount and the slice level at the coordinate positions where the position coordinates are most dense as optimum values.

  When the light quantity and slice level at the coordinate position where the position coordinates recorded by the wafer outer peripheral position detection section are most densely reach a plurality of layers, the light intensity slice level is set with the median value of the plurality of layers as the optimum value. It is preferable to set in parts.

  In the wafer detection method according to the present invention, a plurality of captured images including the outer peripheral edge of the wafer are formed by irradiating the wafer held by the holding table with a plurality of levels of light from the light irradiator and imaging with the camera. And a binarization step of binarizing a captured image captured for each light quantity of a plurality of hierarchies at a slice level of the plurality of hierarchies to form a binarized image after performing the step and the captured image forming step, After performing the wafer outer periphery position detecting step for detecting and recording the boundary position between the white pixel and the black pixel in the binarized image formed in the binarizing step as the coordinate position of the outer periphery of the wafer, the wafer outer periphery position detecting step The light intensity slice level setting step for setting the light intensity and slice level at the coordinate position where the position coordinates recorded in the Therefore, it is possible to image the wafer with the optimal light amount obtained at the light intensity slice level setting step and binarize the image captured at the optimal slice level obtained at the light intensity slice level setting step. The risk of detecting a position different from the actual outer peripheral edge position as the outer peripheral edge of the wafer can be reduced.

It is sectional drawing which shows the state which hold | maintains a wafer with a holding table in a holding step. It is sectional drawing which shows the state which is imaging the wafer with an imaging means. It is a top view which overlaps and shows the some picked-up image of the irradiation light quantity difference including the outer periphery of the wafer formed with the camera and formed in the picked-up image formation part. It is explanatory drawing which binarizes each of the some captured image with the irradiation light quantity difference including the outer periphery of the wafer formed in the captured image formation part by the slice level of a some hierarchy, and forms a binarized image. It is explanatory drawing which shows the binarized image displayed by dividing | segmenting into a white pixel and a black pixel on the virtual output screen in a wafer outer periphery position detection step. It is the plot figure which detected the coordinate position of the outer periphery of a wafer in the wafer outer periphery position detection step, and plotted it on the X-axis Y-axis coordinate system. It is explanatory drawing which shows the binarized image displayed by dividing | segmenting into a white pixel and a black pixel on the virtual output screen in a wafer outer periphery position detection step. It is the plot figure which detected the coordinate position of the outer periphery of a wafer in the wafer outer periphery 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 periphery of the wafer imaged with 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 | segmented and displayed the binarized image binarized by the optimal slice level on the virtual output screen into the white pixel and the black pixel. It is sectional drawing which shows the state which trims the outer periphery of a wafer with a process means.

  Below, the method to detect the outer periphery position of a wafer using the processing apparatus 1 which concerns on this invention is demonstrated.

1 Setting of Optimum Conditions (1) Holding Step A wafer W shown in FIG. 1 is a disk-shaped semiconductor wafer (for example, a silicon wafer), and a surface area Wa includes a device area Wa1 and an outer peripheral area surrounding the device area Wa1. Wa2 is provided. The device region Wa1 is divided into a plurality of regions by the planned division lines S arranged in a lattice pattern, and a device D such as an IC is formed in each region. The outer peripheral edge Wd of the wafer W is chamfered and has a substantially arcuate cross section.

  A processing apparatus 1 shown in FIG. 1 is an apparatus that performs a cutting process on a wafer W and can detect an outer peripheral position of the wafer W. A holding table 30 provided in the processing apparatus 1 for sucking and holding the wafer W shown in FIG. 1 is formed on the outer periphery of the table main body 300 so that an annular holding portion 301 protrudes in the + Z direction. A recess is formed at the center so as to be surrounded. The upper surface of the annular holding portion 301 is an annular holding surface 301 a 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 suction hole (not shown) is formed in the annular holding surface 301a, and a suction source 302 is in communication with the annular groove or suction hole. Note that the holding table 30 is rotatable about at least the Z-axis direction.

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

(2) Captured Image Forming Step The imaging means 2 shown in FIG. 2 provided in the processing apparatus 1 includes a light irradiator 20 that irradiates light onto the wafer W held by the holding table 30, and the wafer W held by the holding table 30. And at least a camera 21 that forms a captured image. The light irradiator 20 can adjust the amount of light emitted from a light source 200 (for example, an LED or a xenon lamp) by a voltage regulator 201. An optical fiber 202 is connected to the light irradiator 20, and light emitted from the light source 200 reaches the inside of the camera 21 through the optical fiber 202. The camera 21 includes a case 210 in which external light is shielded, and a half mirror 211 that is disposed in the case 210 and reflects the light emitted from the light irradiator 20 and incident through the optical fiber 202 downward to change the direction. An objective lens 212 that is disposed below the half mirror 211 and receives 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 light emitted from the light irradiator 20 and incident through the optical fiber 202 to the wafer W, and a function of transmitting 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 surface Wa of the wafer W held on the holding table 30. The image sensor 213 receives the reflected light from the wafer W and outputs a corresponding image. Note that the imaging unit 2 may move up and down and may move in the horizontal plane direction. The camera 21 is connected to a control means 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 falls within the imaging region of the camera 21. In this state, when a predetermined voltage adjusted by the voltage regulator 201 is applied to the light source 200, the light source 200 emits light having 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 through the objective lens 212. Then, the reflected light from the wafer W is collected by the objective lens 212 and formed on the image sensor 213, whereby a captured image including the outer peripheral edge Wd of the wafer W is formed by the camera 21.

  The control unit 9 includes a captured image forming unit 90 that forms a plurality of captured images including the outer peripheral edge Wd of the wafer imaged by the camera 21 by irradiating a plurality of levels of light. The voltage applied to the light source 200 is adjusted by the adjuster 201, and the amount of light applied to the wafer W of the light irradiator 20 is changed by 1% from 1% to 100%, for example, as shown in FIG. , A picked-up image G1, a picked-up image G2,..., A picked-up image Gk,..., A picked-up image Gm (m is 100 in this embodiment). To do. In FIG. 3, the formed captured image G1, the captured image G2,..., The captured image Gk. In addition, the imaging for forming the captured image G1, the captured image G2,..., The captured image Gk, and the captured image Gm is performed by fixing the height position of the camera 21 and the position on the X-axis Y-axis plane. Do. A total of 100 formed captured images G1, captured image G2,... Captured image Gk..., Captured image Gm include a part of the outer peripheral edge of wafer W and a background portion (annular holding surface of holding table 30). 301a) is displayed. The captured image G1, the captured image G2,..., The captured image Gk..., And 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 captured images formed for the light amounts of the plurality of hierarchies at the slice levels of the plurality of hierarchies to form a binarized image. A binarization processing unit 91 is provided. The captured image G1, the captured image G2,..., The captured image Gk..., And the captured image Gm, which are formed by the captured image forming unit 90 and shown in FIG.

The binarization processing unit 91 converts the picked-up image G1, the picked-up image G2,..., The picked-up image Gk,. Respectively to form a plurality of binarized images. That is, the binarization processing unit 91, for example, displays a plurality of captured images G1, captured images G2,... Captured images Gk,. 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, which is converted into a binary image. As shown in FIG. 4, the binarized slice level value is changed by 1 in the range of 0 to 255 for the captured image G1, and binarization processing is performed on the basis of each slice level. Binary images G1 ₀ , G1 ₁ ..., G1 _j ,..., And binary images 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 is a pixel having a luminance value less than the set slice level. The pixel having a luminance value equal to or higher than the set slice level is 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, 256 binarized images are formed for each captured image, so that a total of 25600 binarized images are formed.

(4) Wafer Perimeter Position Detection Step As shown in FIG. 2, the control means 9 determines the boundary between the white pixel and the black pixel in the binarized image formed by the binarization processing unit 91 as the coordinates of the outer peripheral edge of the wafer. A wafer outer peripheral position detecting unit 92 that detects and records 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 The coordinates (x, y) on the X-axis / 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, the detected coordinates are plotted and recorded as black dots on the X-axis Y-axis coordinate system shown in FIG. As shown in FIG. 6, the detected coordinates are plotted in an arc shape that approximates the arc of the wafer W on the X-axis and 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. In this way, 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 the plot E1 is created for the captured image G1. Plot it in the figure. Therefore, in the present embodiment, the wafer outer peripheral position detection unit 92 creates a total of 100 plots 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 detecting step may be performed as follows, for example, in addition to being performed as described above. 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 Divided into pixels for display. 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 ( The black dots in FIG. 8) are recorded.

Similarly, the wafer outer peripheral position detection unit 92 also uses the remaining 255 binarized images G1 ₁ , G1 ₂ ..., G1 _j ,... From the binarized image G1 _{n with} respect to the captured image G1. The coordinates of the intersection (x, y) between the boundary between the white pixel and the black pixel in the converted image region and the broken line L3 are detected as coordinate positions of the outer peripheral edge Wd of the wafer W, respectively, and are shown in FIG. As described above, the acquired coordinates are 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 a total of 256 binarized images G1 ₀ to G1 _n with respect to the captured image G1 in the X-axis Y-axis coordinate system. A plot diagram F1 plotted in FIG. As shown in FIG. 8, on the X-axis Y-axis coordinate system of the plot diagram F1, 256 coordinates detected on the same Y-coordinate are plotted linearly in the X-axis direction. A straight line extending in the Y-axis direction with a constant X coordinate is set on the virtual output screen B, and the white in each binarized image area in the binarized images G1 ₀ to G1 _n is set. The intersection (x, y) between the boundary between the pixel and the black pixel and a straight line extending in parallel with the Y-axis direction may be plotted and stored.

  Further, the wafer outer peripheral position detection unit 92 also uses the coordinate position of the outer peripheral edge Wd of the wafer W as the X-axis and Y-axis coordinate system for the binarized images with respect to the captured images G2 to Gm, as in the case of creating the plot F1. Create a plot diagram plotted in. Therefore, in the present embodiment, the wafer outer peripheral position detection unit 92 creates a total of 100 plots 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 quantity slice level setting step As shown in FIG. 2, the control means 9 sets the light quantity and slice level at the coordinate position where the position coordinates recorded by the wafer outer periphery position detector 92 are most dense as the optimum values. A light amount slice level setting unit 93 is provided. First, a total of 100 plots including the plot E1 shown in FIG. 6 are transferred from the wafer outer periphery 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 where the position coordinates indicated by the black dots are most dense in the plot diagram E1 shown in FIG. 6, and the binary value used when plotting the coordinates in this region. The binarized image is specified from the binarized image G1 ₀ to the binarized image G1 _n . Furthermore, 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 specified binarized image is one G1 _j (for example, j is 140), the specified slice level is also the slice level j (for example, slice level 140). When there are three binarized images such as binarized image G1 _j−1 , binarized image G1 _j , binarized image G1 _{j + 1} , the specified slice level is also slice level (j−1), Slice level j, slice level (j + 1), that is, slice level 139, slice level 140, and slice level 141 are obtained.

  The light amount slice level setting unit 93 specifies slice levels in the same manner for the remaining 99 plots. For example, when the slice level specified from all the plot diagrams becomes one slice level j (for example, slice level 140), the slice level 140 is determined as the optimum value. The slice levels specified from all plot diagrams span three levels: slice level (j−1), slice level j, 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 amount slice level setting unit 93 determines the optimum value of the irradiation light amount from the light irradiator 20 shown in FIG. For example, 100 plot diagrams including the plot diagram E1 are converted into plot diagrams each including only a plot based on the binarized image formed at the slice level 140, respectively. Further, the converted plot diagrams are displayed with the X-axis and Y-axis in the respective plot diagrams coincident with each other and output on the same plane, for example, a bi-plot diagram is created. The light quantity slice level setting unit 93 specifies, for example, an area where position coordinates are most dense from the biplot diagram, and uses the binarized image used when plotting the coordinates in this area as 100 binary images. The binarized image G1 ₁₄₀ , the binarized image G2 ₁₄₀ ,..., And the binarized image Gm ₁₄₀ are specified. Furthermore, the light quantity slice level setting unit 93 specifies a captured image before binarization of the specified binarized image from the specified binarized image. For example, when there is only one identified captured image and this one is captured with an irradiation light amount of 55%, the optimum irradiation light amount for the wafer W of the specified light irradiator 20 is also 55%. It becomes. For example, when there are three specified captured images, and these three images are 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 median value of the irradiation light quantity of 55% is finally determined as the optimum value. 6 includes the plot diagram F1 shown in FIG. 8 instead of the plot diagram of 100 diagrams in which the coordinate position of the outer peripheral edge Wd of the wafer W including the plot diagram E1 shown in FIG. 6 is plotted in the X-axis Y-axis coordinate system. The optimum values of the slice level and the irradiation light amount may be determined using the plot diagram of FIG. In this case, since a part of the outer peripheral edge in the binarized image may be used, the time required for the process for obtaining the optimum condition can be shortened.

2 Detection of wafer outer peripheral position and processing of wafer After performing the light amount slice level setting step, the light amount slice level setting unit 93 finally determines the optimum value as the slice level 140 and the irradiation light amount 55%, Cutting processing for trimming the wafer W into a circular shape is performed by the processing apparatus 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 falls within the imaging region 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 with an irradiation light quantity of 55%. Irradiation is performed on the wafer W, and a captured image G55 including the outer peripheral edge Wd of the wafer W shown in FIG. 9 is formed.

The formed captured image G55 is transferred from the camera 21 shown in FIG. 2 to the control unit 9, and binarized at the slice level 140 by the binarization processing unit 91 of the control unit 9, whereby the binary image shown in FIG. A valued image G55 ₁₄₀ is formed. Two to the value processing unit 91 to the wafer peripheral position detector 92 binary image _{G55 140} are transferred, the wafer peripheral position detector 92, the binarized image _{G55 140,} as shown in FIG. 10, for example resolution 1600 Each of the coordinates on the X-axis Y-axis plane of the boundary between the white pixel and the black pixel in the binarized image G55 ₁₄₀ region is displayed by being divided into white pixels and black pixels on the × 1200 virtual output screen B. (X, y) are successively detected as the coordinate position of the outer peripheral edge Wd of the wafer W.

  In this way, at the stage of setting the optimum conditions, the light quantity and slice level conditions for reliably detecting the outer periphery of the wafer W are obtained, and the wafer W to be actually processed is imaged under those conditions. By detecting the outer peripheral edge Wd, the possibility of detecting a position different from the actual outer peripheral edge position as the outer peripheral edge Wd of the wafer W can be reduced.

After the coordinate position of the outer peripheral edge Wd of the wafer W is detected by the wafer outer peripheral position detector 92, 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. It is 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 a spindle 60 whose axial direction is the Y-axis direction, and a motor 62 that rotationally drives the spindle 60, The cutting blade 63 attached to the tip of the spindle 60 is provided, and the cutting blade 63 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 with reference to the coordinate position of the outer peripheral edge Wd of the wafer W detected by the wafer outer peripheral position detection unit 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 on the radially inner side by a predetermined distance. For example, the cutting blade 63 is positioned so that about 2/3 of the end face of the cutting blade 63 contacts the outer peripheral area Wa2 of the wafer W including the outer peripheral edge Wd of the wafer W.

  Next, the motor 62 rotates the spindle 60 at a high speed in the counterclockwise direction when viewed from the + Y direction side, whereby the blade 63 fixed to the spindle 60 is rotated 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 surface Wa of the wafer W by a predetermined depth. The cutting depth of the cutting blade 63 is determined based on, for example, 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 has been cut and fed to a predetermined height position, the holding blade 30 is kept rotating 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. The entire outer periphery Wd of the wafer W is cut and trimmed by rotating 360 degrees. 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 light quantity and slice level conditions for reliably detecting the outer peripheral edge Wd of the wafer W are obtained, and the wafer W to be actually processed is imaged under those conditions. Since the outer peripheral edge Wd is detected and the blade 63 is cut using the position as a reference, a 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 amount of light applied to the wafer W and the slice level hierarchy at the time of binarization are not limited to the example of this embodiment.

1: Processing device 30: Holding table 300: Table body 301: Annular holding part 301a: Annular holding surface 302: Suction source 2: Imaging means 20: Light irradiator 200: Light source 201: Voltage regulator 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 part 91: Binarization processing part 92: Wafer outer peripheral position Detection unit 93: Light quantity slice level setting unit W: Wafer Wa: Wafer surface Wb: Wafer back surface Wa1: Device region Wa2: Peripheral region S: Divided line D: Device Wd: Outer periphery

Claims (4)

A holding table having a holding surface for holding the wafer; a light irradiator for irradiating light to the wafer held by the holding table; and a camera for imaging the wafer held by the holding table and forming a picked-up image. A wafer detection method for detecting the outer peripheral position of the wafer using an apparatus equipped with an imaging means,
A holding step for holding the wafer on the holding table;
After carrying out the holding step, a captured image that irradiates the wafer held by the holding table with a plurality of levels of light from the light irradiator and picks up images with the camera to form a plurality of picked-up images including the outer peripheral edge of the wafer Forming step;
After performing the captured image forming step, a binarization step of binarizing the captured image captured for each light quantity of a plurality of layers at a slice level of the plurality of layers to form a binarized image;
A wafer outer peripheral position detecting step for 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 the outer peripheral edge of the wafer;
A wafer detection method comprising: a light amount slice level setting step for setting the light amount and slice level at coordinate positions where the position coordinates recorded in the wafer outer peripheral position detection step are most densely set as optimum values.   When the light quantity and slice level at the coordinate position where the position coordinates recorded in the wafer outer peripheral position detection step are most densely reach a plurality of layers, the light intensity slice level setting is made with the median value of the plurality of layers as the optimum value. The wafer detection method according to claim 1, wherein the wafer detection method is set in steps. A holding table having a holding surface for holding the wafer; a light irradiator for irradiating light to the wafer held by the holding table; and a camera for imaging the wafer held by the holding table and forming a picked-up image. A processing apparatus comprising: the imaging means; a processing means for processing the wafer held by the holding table; and a control means for controlling at least the processing means,
The control means includes
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 wafer held by the holding table with a plurality of levels of light from the light irradiator and picked up by the camera;
A binarization processing unit that binarizes the captured images formed for each light quantity of a plurality of layers at a slice level of the 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 the outer peripheral edge of the wafer;
A processing apparatus comprising: a light amount slice level setting unit that sets the light amount and slice level at coordinate positions where the position coordinates recorded by the wafer outer periphery position detection unit are most densely set as optimum values.   When the light quantity and slice level at the coordinate position where the position coordinates recorded by the wafer outer peripheral position detection section are most densely reach a plurality of layers, the light intensity slice level is set with the median value of the plurality of layers as the optimum value. The wafer processing apparatus according to claim 3, which is set by a unit.

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