JP5215159B2 - Alignment mechanism, grinding apparatus, alignment method and grinding method - Google Patents

Description

  The present invention relates to a positioning mechanism, a grinding apparatus, a positioning method, and a grinding method for adjusting the position of a semiconductor wafer when grinding the semiconductor wafer.

  A semiconductor chip on which a device such as an IC or LSI is formed is indispensable for downsizing various electronic devices. In this semiconductor chip, the surface of a semiconductor wafer as a substantially disk-shaped workpiece is divided into a plurality of rectangular areas by grid-like divided division lines (streets), and devices are formed in each divided rectangular area, and then divided. Manufactured by dividing a rectangular region along a line.

  In such a semiconductor chip manufacturing process, the semiconductor wafer is divided into a predetermined thickness by grinding the back surface on the opposite side of the device surface on which the device is formed prior to the division. By thinning the semiconductor wafer, the heat dissipation is improved in addition to the reduction in size and weight of the electronic device. However, the thinned semiconductor wafer has a problem that the rigidity is lowered as compared with the semiconductor wafer before thinning, and warpage is generated and the conveyance risk is high.

  Therefore, in order to solve this problem, only the region corresponding to the device formation region on which the device is to be formed on the back surface of the semiconductor wafer is ground to form a concave shape, and a reinforcing protrusion is formed in the outer peripheral region of the device region. doing. The rigidity of the semiconductor wafer is ensured by the reinforcing convex portions, and warpage and transport risk are reduced. Thus, the reinforcement convex part is removed from the semiconductor wafer in which the reinforcement convex part was formed before the dicing process.

  Generally, in order to remove the reinforcing convex portion, grinding is performed by vertical axis surface grinding, and the removal amount of the reinforcing convex portion is ground while being monitored by a contact sensor. This contact sensor detects the amount of removal by bringing a contactor into contact with the upper surface of the reinforcing convex portion of the semiconductor wafer held by the rotating chuck table.

Conventionally, as a positioning mechanism for aligning a semiconductor wafer with a chuck table when removing a reinforcing convex portion, the center position of the semiconductor wafer is calculated from image data, and the center of the semiconductor wafer is aligned with the center of the chuck table. The thing is known (refer patent document 1). This conventional alignment mechanism images the outer peripheral edge of a semiconductor wafer and calculates the center position of the semiconductor wafer from the captured image data. The alignment mechanism calculates the amount of variation up to the center of the chuck table from the calculated center of the semiconductor wafer as a base point, and aligns the center of the semiconductor wafer with the center of the chuck table.
JP 2007-19379 A

  By the way, the center of the semiconductor wafer and the center of the inner periphery defined by the inner peripheral edge of the reinforcing convex portion (hereinafter referred to as the inner peripheral edge center) do not necessarily coincide with each other. This is because there is a case where the deviation occurs due to an error or there is a case where the inner peripheral edge center of the reinforcing convex portion is intentionally removed from the center of the semiconductor wafer when the reinforcing convex portion is formed. As described above, since the outer periphery of the semiconductor wafer and the inner periphery of the reinforcing convex portion are eccentric, in a grinding apparatus having a conventional alignment mechanism, the contact of the contact sensor is arranged around the reinforcing convex portion. In order to keep the contact in the direction, it is necessary to bring the contact into contact with the vicinity of the outer periphery of the reinforcing convex portion.

  However, since there are orientation flats and notches on the outer periphery of the semiconductor wafer, the contact cannot be contacted near the outer periphery of the reinforcing convex portion, and the contact is brought into contact with the inner periphery of the reinforcing convex portion. In some cases, the contact may come off from the upper surface of the reinforcing convex portion during grinding of the reinforcing convex portion. Therefore, the conventional alignment mechanism has a problem that it is difficult to perform alignment so that the contact does not come off from the reinforcing convex portion.

  The present invention has been made in view of the above points, and in a work in which a reinforcing convex portion is formed in a disk-shaped outer peripheral region, the contact of the contact sensor is not removed from the reinforcing convex portion. An object of the present invention is to provide an alignment mechanism, a grinding apparatus, an alignment method, and a grinding method.

  The alignment mechanism of the present invention has a device formation region where a device is formed on the front surface and an outer peripheral region around the device formation region, and removes a region corresponding to the device formation region on the back surface. An inner peripheral edge position data acquisition unit for acquiring position data of an inner peripheral edge of the reinforcing convex part of the workpiece formed so that a reinforcing convex part protrudes from an area corresponding to the outer peripheral area, and the reinforcing convex An inner peripheral edge center position data calculation unit that calculates position data of the inner peripheral edge center indicating the center of the inner periphery defined in the inner peripheral edge of the reinforcing convex portion based on the position data of the inner peripheral edge of the portion A holding surface center position data storage unit that stores position data of the holding surface center indicating the center of the holding surface of the holding table that holds the workpiece, position data of the inner peripheral edge center, and a position of the holding surface center Based on data There are, as well as aligning the inner peripheral edge portion around the holding surface center, characterized in that the workpiece and a position mating mounting portion is placed on the holding surface.

  The alignment method of the present invention has a device formation region where a device is formed on the front surface and an outer peripheral region around the device formation region, and removes a region corresponding to the device formation region on the back surface, Obtaining position data of the inner peripheral edge portion of the reinforcing convex portion from a work formed such that the reinforcing convex portion protrudes from a region corresponding to the outer peripheral region; and Based on the position data, calculating the position data of the inner peripheral edge center indicating the center of the inner peripheral edge defined at the inner peripheral edge of the reinforcing convex portion; and a holding table for holding the work stored in advance Based on the position data of the holding surface center indicating the center of the holding surface and the position data of the inner peripheral edge center, the center of the inner peripheral edge portion is aligned with the center of the holding surface, and the work is placed on the holding surface. Characterized by a step of.

  According to these configurations, the position data of the center of the inner peripheral edge of the convex portion for reinforcing the workpiece is calculated, the position data of the calculated center of the inner peripheral edge and the position data of the center of the holding surface of the stored holding surface; Since the workpiece is placed on the holding surface based on the above, the center of the inner peripheral edge of the reinforcing convex portion of the workpiece can be aligned with the holding surface center of the holding table. Further, when this positioning mechanism is used in, for example, a grinding apparatus, the center of the inner peripheral edge of the reinforcing convex portion of the workpiece can be aligned with the center of the holding surface of the holding table. By contacting the contact sensor of the contact type sensor with the upper surface near the inner periphery of the inner surface, the contact can be continuously made in the circumferential direction, and the reinforcement protrusion can be accurately monitored while monitoring the removal amount of the reinforcement protrusion. The part can be ground.

  According to the alignment mechanism of the present invention, the temporary placement table that is rotatable in a state where the workpiece is temporarily placed is provided, and the inner peripheral edge position data acquisition unit rotates the temporary placement table to perform the reinforcement. Position data of the inner peripheral edge portion of the convex portion for use is acquired.

  Further, according to the alignment mechanism of the present invention, the inner peripheral edge center position data calculation unit extracts three points from the position data of the inner peripheral edge of the reinforcing convex portion, and points A, B, C The intersection of the vertical bisector connecting the point A and the point B with the vertical bisector connecting the point A and the point C is the center of the inner peripheral edge. Is calculated as position data.

  Further, according to the alignment mechanism of the present invention, the inner peripheral edge position data acquisition unit images the inner peripheral edge of the reinforcing convex portion, and the image data obtained by the imaging is used as the reinforcing convex portion. It is acquired as position data of the inner peripheral edge.

  The grinding apparatus according to the present invention includes the above positioning mechanism and a grinding mechanism that grinds the reinforcing convex portion of the workpiece in a state where the center of the inner peripheral edge is aligned with the center of the holding surface. Yes.

  Further, the grinding method of the present invention includes the steps of the alignment method described above, and the step of grinding the reinforcing convex portion of the workpiece in a state where the center of the inner peripheral edge is aligned with the center of the holding surface. doing.

  In addition, according to the grinding apparatus of the present invention, the grinding device has a mounting surface on which the ground workpiece on which the reinforcing convex portion has been ground by the grinding mechanism is placed, and for spinner cleaning the ground workpiece. A spinner cleaning table, a cleaning mounting portion for mounting the ground workpiece on the mounting surface of the spinner cleaning table from a holding surface of the holding table, and a mounting surface center indicating the center of the mounting surface A mounting surface center position data storage unit for storing position data, and the inner peripheral edge position data acquisition unit includes the outer peripheral edge part of the reinforcing convex part together with the position data of the inner peripheral part of the reinforcing convex part. The inner peripheral edge center position data calculation unit indicates the center of the workpiece based on the position data of the outer peripheral edge of the reinforcing convex portion together with the position data of the inner peripheral edge center. Position of workpiece center And the cleaning mounting portion aligns the workpiece center with the placement surface center based on the workpiece center position data and the placement surface center position data, and The work is placed on the mounting surface.

  According to the present invention, in the workpiece in which the reinforcing convex portion is formed in the disk-shaped outer peripheral region, the center of the inner peripheral edge of the reinforcing convex portion can be aligned with the center of the holding table.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, before describing the alignment mechanism according to the embodiment of the present invention, a semiconductor wafer to be processed will be briefly described. FIG. 1 is an external perspective view of a semiconductor wafer before processing according to the first embodiment of the present invention, wherein (a) shows the front surface of the semiconductor wafer and (b) shows the back surface of the semiconductor wafer.

  As shown in FIG. 1A, the unprocessed semiconductor wafer W is formed in a substantially disc shape, and is partitioned into a plurality of regions by unillustrated division lines arranged in a lattice pattern on the surface. A device 95 such as an IC or LSI is formed in the center of the semiconductor wafer W in each region partitioned by the division lines. In addition, the surface of the semiconductor wafer W is divided into a device formation region 96 in which the device 95 located in the central portion is formed and an outer peripheral region 97 located around the device formation region 96. In the outer peripheral region 97, a notch 90 indicating a crystal orientation is formed.

  As shown in FIG. 1B, the back surface of the semiconductor wafer W has a region corresponding to the device formation region 96 removed, and a region corresponding to the outer peripheral region 97 protrudes in an annular shape to form a reinforcing convex portion 98. Yes. As described above, the recess 99 is formed on the back surface of the semiconductor wafer W, and only the device forming region 96 is thinned. The semiconductor wafer W in which the concave portion 99 is formed is accommodated in the cassette 2 (see FIG. 2) and is carried into the grinding apparatus 1.

  In the present embodiment, a semiconductor wafer W such as a silicon wafer will be described as an example of a workpiece. However, the present invention is not limited to this configuration, and the semiconductor product package, ceramic, glass, sapphire, silicon Substrate, various electrical components, and various processing materials that require micron order accuracy may be used as the workpiece. Further, the reinforcing convex portion 98 is not limited to the one formed in an annular shape, and may be any one that reinforces the warp and strength of the workpiece, and may be formed in an arc shape, for example.

  Next, an example in which the alignment mechanism according to the first embodiment of the present invention is applied to a grinding apparatus will be described with reference to FIGS. FIG. 2 is an external perspective view of the grinding apparatus according to the first embodiment of the present invention. FIG. 3 is a partially enlarged view of the grinding apparatus according to the first embodiment of the present invention.

  Note that the grinding apparatus according to the present embodiment is for removing the reinforcing convex portions formed on the outer peripheral edge portion of the back surface of the semiconductor wafer before the dicing step in order to reduce warpage and conveyance risk. Further, in the following description, an example in which the alignment mechanism is applied to a grinding apparatus will be described. However, not only the grinding apparatus but also the center of the inner periphery of the reinforcing peripheral portion of the semiconductor wafer (hereinafter referred to as the inner peripheral edge). It is also possible to apply to a processing apparatus that performs position alignment (with the center of the part).

  As shown in FIG. 2, the grinding device 1 carries in a semiconductor wafer W before processing, a loading / unloading unit 4 for unloading the semiconductor wafer W after processing, and a semiconductor wafer W loaded from the loading / unloading unit 4. The reinforcing convex portion 98 is composed of a convex portion removing unit 5 that grinds and removes the reinforcing convex portion 98. The carry-in / carry-out unit 4 has a rectangular parallelepiped base 11, and the base 11 is provided with a pair of cassette placement portions 12 and 13 on which the cassettes 2 and 3 are placed so as to protrude forward from the front surface 11a. It has been.

  The cassette mounting unit 12 functions as a carry-in port, and the cassette 2 in which the unprocessed semiconductor wafer W is stored is mounted. The cassette mounting portion 13 functions as a carry-out port, and the cassette 3 in which the processed semiconductor wafer W is accommodated is mounted. On the upper surface of the base 11, a carry-in / carry-out arm 14 is provided so as to face the cassette mounting parts 12, 13, and the temporary placement part is adjacent to the carry-in / carry-out arm 14 at one corner on the convex part removal unit 5 side. 15. Spinner cleaning units 16 are provided at the other corners, respectively. In addition, on the upper surface of the base 11, a wafer supply unit 17 and a wafer recovery unit 18 are provided between the temporary placement unit 15 and the spinner cleaning unit 16. Furthermore, a control unit 19 that performs overall control of the loading / unloading unit 4 is provided inside the base 11.

  The carry-in / carry-out arm 14 includes a multi-node link mechanism 21 having a wide driving area, and a suction holding unit 22 that is provided at the tip of the multi-node link mechanism 21 and holds the semiconductor wafer W by suction. The suction holding portion 22 is formed in a disk shape having a smaller diameter than the inner peripheral edge portion of the reinforcing convex portion 98 of the semiconductor wafer W, and holds the concave portion 99 of the semiconductor wafer W by suction. The carry-in / carry-out arm 14 drives the multi-joint link mechanism 21 to place the semiconductor wafer W accommodated in the carry-in cassette 2 on the temporary placement unit 15 and from the spinner cleaning unit 16 into the carry-out cassette 3. The semiconductor wafer W is accommodated in

  As illustrated in FIG. 3, the temporary placement unit 15 includes a temporary placement table 24 on which the semiconductor wafer W is temporarily placed by the loading / unloading arm 14, and an imaging unit 25 that images the semiconductor wafer W temporarily placed on the temporary placement table 24. And have. The imaging unit 25 is provided above the base 11 via the support member 26 and images the upper surface of the semiconductor wafer W temporarily placed on the temporary placement table 24. The imaging unit 25 is configured to be movable in the radial direction of the temporary placement table 24, and thereby the imaging position in the radial direction of the semiconductor wafer W is adjusted. The temporary placement table 24 is rotated by a rotation driving mechanism (not shown), and the imaging position in the circumferential direction of the semiconductor wafer W is adjusted by driving the rotation driving mechanism.

  The position of the semiconductor wafer W temporarily placed on the temporary placement table 24 is adjusted so that the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W are included in the imaging range, and the image is taken by the imaging unit 25. . Image data captured by the imaging unit 25 is output to the control unit 19. In this way, since the inner peripheral edge and the outer peripheral edge can be simultaneously imaged by one imaging unit 25, it is possible to reduce the number of components and the number of imaging.

  The wafer supply unit 17 is provided with a pivot shaft 31 extending in the vertical direction, an extendable arm 32 supported on the upper end of the pivot shaft 31, and a suction for holding the semiconductor wafer W by suction. Holding part 33. The suction holding portion 33 is formed in a disk shape having a smaller diameter than the inner peripheral edge portion of the reinforcing convex portion 98 of the semiconductor wafer W, and holds the concave portion 99 of the semiconductor wafer W by suction. The rotation shaft 31 is configured to be movable up and down, back and forth, and rotatable, and the extendable arm 32 is configured to be extendable and contractable in the extending direction. The suction holding portion 33 is adjusted in position in the horizontal plane by the forward / backward movement and rotation of the rotation shaft 31 and the expansion / contraction of the telescopic arm 32, and is adjusted in the height direction by the vertical movement of the rotation shaft 31.

  The wafer supply unit 17 is driven and controlled by the control unit 19, and the control unit 19 adjusts the vertical movement amount, the front-rear movement amount, the rotation amount, and the expansion / contraction amount of the telescopic arm 32. Is done. Then, the wafer supply unit 17 is controlled by the control unit 19 to suck and hold the semiconductor wafer W from the temporary placement table 24, and supplies the semiconductor wafer W to the chuck table 52. At this time, the center of the inner peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W is aligned with the center of the holding surface 56 of the chuck table 52 of the convex portion removing unit 5 (hereinafter referred to as the holding surface center). ing.

  The wafer collection unit 18 has substantially the same configuration as the wafer supply unit 17 except that the suction holding unit 37 is formed to have a larger diameter than the suction holding unit 33 of the wafer supply unit 17. The wafer recovery unit 18 is controlled by the control unit 19 to suck and hold the semiconductor wafer W from the chuck table 52 and recover it, and places it on the spinner cleaning table 41 of the spinner cleaning unit 16. At this time, alignment is performed so that the center of the semiconductor wafer W (hereinafter referred to as the wafer center) coincides with the center of the mounting surface 42 (hereinafter referred to as the mounting surface center) of the spinner cleaning table 41 of the spinner cleaning unit 16. Has been.

  Returning to FIG. 2, the spinner cleaning unit 16 includes a spinner cleaning table 41 on which the processed semiconductor wafer W is placed. The spinner cleaning table 41 has a disk shape and has a mounting surface 42 on which the semiconductor wafer W is mounted. At the center of the mounting surface 42, a suction surface 42a is formed in a circular shape by a porous ceramic material. The suction surface 42a is connected to a suction source (not shown) disposed in the base 11 and holds the semiconductor wafer W by suction.

  When the processed semiconductor wafer W is placed on the spinner cleaning table 41, the semiconductor wafer W is accommodated in the base 11 through the opening 43 by the lowering of the spinner cleaning table 41. The semiconductor wafer W accommodated in the base 11 is cleaned by being sprayed with cleaning water while being rotated at a high speed. Thereafter, the jet of cleaning water is stopped in a state where the semiconductor wafer W is rotated at a high speed, and the semiconductor wafer W is dried.

  The control unit 19 performs imaging processing of the semiconductor wafer W by the imaging unit 25, calculation processing of the inner peripheral edge center and the wafer center of the semiconductor wafer W, alignment processing of the semiconductor wafer W with respect to the chuck table 52 and the spinner cleaning table 41, and the like. Execute the process. Further, the control unit 19 stores an orthogonal plane coordinate system (see FIGS. 6 and 8) used for the alignment process together with a control program for each process.

  In addition, the control part 19 calculates the data in RAM (Random Access Memory) according to various programs, such as a control program in ROM (Read Only Memory), and CPU (Central Processing Unit) incorporated in the inside, and the carrying in / out unit 4 Each process is executed in cooperation with each part. Details of imaging processing of the semiconductor wafer W, calculation processing of the inner peripheral edge center and the wafer center of the semiconductor wafer W, and alignment processing of the semiconductor wafer W with respect to the chuck table 52 and the spinner cleaning table 41 will be described later.

  The convex portion removing unit 5 is configured to relatively rotate the rough grinding unit 45 and the finish grinding unit 46 and the chuck table 52 holding the semiconductor wafer W to grind the reinforcing convex portion 98 of the semiconductor wafer W. . The convex portion removal unit 5 has a rectangular parallelepiped base 51, and the carry-in / out unit 4 is connected to the front surface of the base 51. A turntable 53 on which three chuck tables 52 are arranged is provided on the upper surface of the base 51, and a column portion 54 is erected on the rear side of the turntable 53.

  The turntable 53 is formed in a large-diameter disk shape, and three chuck tables 52 are arranged on the upper surface at intervals of 120 degrees in the circumferential direction. The turntable 53 is connected to a rotation drive mechanism (not shown), and is intermittently rotated at intervals of 120 degrees in the D1 direction by the rotation drive mechanism. As a result, the three chuck tables 52 are provided at a transfer position where the semiconductor wafer W is transferred between the wafer supply unit 17 and the wafer recovery unit 18, a rough grinding position where the semiconductor wafer W is opposed to the rough grinding unit 45, and finish grinding. The unit 46 is moved between finish grinding positions where the semiconductor wafer W is opposed to the unit 46.

  The chuck table 52 has a disc shape and has a holding surface 56 on which the semiconductor wafer W is held (see FIG. 3). At the center portion of the holding surface 56, a suction surface 56a is formed in a circular shape by a porous ceramic material. The suction surface 56 a is connected to a suction source (not shown) disposed in the base 51 and holds the semiconductor wafer W by suction. The chuck table 52 is connected to a rotation driving mechanism (not shown), and is rotated while the semiconductor wafer W is held on the holding surface 56 by the rotation driving mechanism.

  On the upper surface of the base 51, a contact sensor 58 is provided in the vicinity of the rough grinding position and the finish grinding position of the turntable 53. This contact sensor 58 has two contacts 61, 62, one contact 61 being in contact with the upper surface of the reinforcing convex portion 98 of the semiconductor wafer W, and the other contact 62 being the upper surface of the chuck table 52. Is touching. The grinding depth is controlled from the difference in height between the two contactors 61 and 62. Further, the contact 61 is in contact with the inner side of the upper surface of the reinforcing convex portion 98 of the semiconductor wafer W so as to avoid the notch 90 (see FIGS. 7C and 7D).

  The support portion 54 is formed in a base shape with a pair of slopes as viewed from above, and grinding unit moving mechanisms 64 and 65 for moving the rough grinding unit 45 and the finish grinding unit 46 above the chuck table 52 on the pair of slopes. Is provided. The grinding unit moving mechanism 64 moves in the R1 direction with respect to the support 54 by a ball screw type moving mechanism, and moves in the vertical direction with respect to the R axis table 67 with a ball screw type moving mechanism. And a Z-axis table 71. A rough grinding unit 45 is supported on the Z-axis table 71 via a support portion 74 attached to the front surface. Further, the grinding unit moving mechanism 65 has the same configuration as the grinding unit moving mechanism 64, and the finish grinding unit 46 is supported.

  The rough grinding unit 45 has a grinding wheel 73 that is detachably attached to the lower end of a spindle (not shown). The grinding wheel 73 is constituted by a diamond grinding stone in which diamond abrasive grains are hardened with a binder such as a metal bond or a resin bond. The grinding wheel 73 is formed in a thin cylindrical shape and has a ring-shaped grinding surface. The finish grinding unit 46 has the same configuration as that of the rough grinding unit 45, but a grinding wheel 73 having a fine grain size is used.

  The rough grinding unit 45 is positioned in the radial direction of the grinding wheel 73 with respect to the semiconductor wafer W by the grinding unit moving mechanism 64, and in the Z-axis direction while monitoring the grinding amount of the reinforcing convex portion 98 by the contact sensor 58. It is fed by grinding.

  Here, with reference to FIG. 4, the imaging process of the semiconductor wafer by the imaging unit will be described. FIG. 4 is an explanatory diagram of the imaging process of the semiconductor wafer by the imaging unit.

  As shown in FIG. 4A, in an initial state where the semiconductor wafer W is not temporarily placed on the temporary placement table 24, the imaging unit 25 is located at a retracted position on the radially outer side of the temporary placement table 24. From this state, as shown in FIG. 4B, when the semiconductor wafer W held by the carry-in / out arm 14 is temporarily placed on the upper surface of the temporary placement table 24, the imaging unit 25 moves the outer peripheral portion of the semiconductor wafer W. Move to the imaging position for imaging.

  When the imaging unit 25 moves to the imaging position, the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W are included in the imaging range of the imaging unit 25 as shown in FIG. The imaging unit 25 images the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W, and the captured image data is output to the control unit 19. When imaging by the imaging unit 25 is completed, the imaging unit 25 moves to the retracted position and enters an initial state.

  With reference to FIG. 5, the calculation process of the center of the inner peripheral edge of the semiconductor wafer and the center of the wafer by the control unit will be described. FIG. 5 shows image data captured by the imaging unit. In the following description, an example in which the center of the inner peripheral edge of the semiconductor wafer W and the center of the wafer do not match will be described for convenience.

  The image data output to the control unit 19 is subjected to edge detection processing by the control unit 19 to obtain curves indicating the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W. When the curves of the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W are obtained, the coordinates of the points A, B, and C are arbitrarily extracted from the curve of the inner peripheral edge. The coordinates of points D, E, and F are arbitrarily extracted from the curve.

  The intersection 75 of the bisector perpendicular to the line connecting the points A and B and the bisector perpendicular to the line connecting the points A and C is the center of the inner peripheral edge of the semiconductor wafer W. Is calculated as On the other hand, the intersection point 76 of the bisector perpendicular to the line connecting the points D and E and the bisector perpendicular to the line connecting the points D and F is calculated as the wafer center of the semiconductor wafer W. Is done.

  In this embodiment, after detecting the curves of the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98, three points are detected. However, the curves of the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 are detected. It is good also as a structure which detects 3 points | pieces directly, without detecting. Thereby, it is possible to reduce the detection processing amount and improve the calculation speed.

  With reference to FIG. 6, the alignment process of the semiconductor wafer with respect to the chuck table will be described. FIG. 6 is an explanatory diagram of the alignment process of the semiconductor wafer with respect to the chuck table.

  As shown in FIG. 6, the control unit 19 has an orthogonal plane coordinate system composed of an X axis and a Y axis. In this orthogonal plane coordinate system, coordinates of the holding surface center of the chuck table 52 stored in advance are stored. 79, the coordinate 77 of the center of the inner peripheral edge of the semiconductor wafer W, and the coordinate 78 of the wafer center are set. Based on the difference between the coordinates 79 of the holding surface center of the chuck table 52 and the coordinates 77 of the center of the inner peripheral edge of the semiconductor wafer W by the control unit 19, the amount of movement of the rotation axis 31 of the wafer supply unit 17 in the front-rear direction. And the amount of rotation and the amount of expansion / contraction of the telescopic arm 32 are calculated.

  From the state where the wafer supply unit 17 is located above the temporary placement table 24, the rotation shaft 31 is moved downward, and the semiconductor wafer W before processing is sucked and held by the suction holding unit 33 and moved up. Next, the wafer supply unit 17 drives the rotation shaft 31 according to the movement amount and the rotation amount of the rotation shaft 31 in the front-rear direction calculated by the control unit 19. Next, the wafer supply unit 17 drives the expansion / contraction arm 32 according to the expansion / contraction amount of the expansion / contraction arm 32 calculated by the control unit 19 to position the semiconductor wafer W above the chuck table 52. Next, the wafer supply unit 17 lowers the rotation shaft 31 to release the suction of the suction holding unit 33. In this way, the semiconductor wafer W is placed on the chuck table 52 with the center of the inner peripheral edge aligned with the center of the holding surface.

  With this configuration, when the center of the inner peripheral edge of the semiconductor wafer W is accurately aligned with the center of the holding surface of the chuck table 52, the contact 61 of the contact sensor 58 is placed on the upper surface of the reinforcing convex portion 98 of the semiconductor wafer W. It is possible to make continuous contact along the circumferential direction. Specifically, as shown in FIG. 7A, the contact 61 is in contact with the inner side of the upper surface of the reinforcing convex portion 98 so as to avoid the notch 90, so that the chuck table 52 is centered on the holding surface. If the centers of the inner peripheral edges of the semiconductor wafer W do not coincide with each other, the contact 61 will be disengaged from the upper surface of the reinforcing convex portion 98 when the chuck table 52 rotates as shown in FIG.

  However, as shown in FIG. 7C, if the center of the inner peripheral edge of the semiconductor wafer W coincides with the center of the holding surface of the chuck table 52 as in the present embodiment shown in FIG. Even if the chuck table 52 rotates while the contact 61 is in contact with the inner side of the upper surface of the reinforcing convex portion 98, the contact 61 does not come off the upper surface of the reinforcing convex portion 98. Therefore, the contact 61 of the contact sensor 58 is brought into contact with the upper surface of the reinforcing convex portion 98 of the semiconductor wafer W, and the reinforcing convex portion 98 is accurately ground while monitoring the removal amount of the reinforcing convex portion 98. Is possible.

  With reference to FIG. 8, the alignment process of the semiconductor wafer with respect to the spinner cleaning table will be described. FIG. 8 is an explanatory diagram of the alignment process of the semiconductor wafer with respect to the spinner cleaning table.

  As shown in FIG. 8, the control unit 19 has an orthogonal plane coordinate system composed of an X axis and a Y axis, and the orthogonal plane coordinate system includes a center of the placement surface of the spinner cleaning table 41 stored in advance. The coordinates 80 and the wafer center coordinates 78 of the semiconductor wafer W are set. The wafer center coordinates 78 of the semiconductor wafer W at this time are not coordinates in the state where the semiconductor wafer W is placed on the temporary placement table 24, but in a state where the semiconductor wafer W is placed on the chuck table 52. The coordinates are shown. That is, the coordinates after moving the wafer center coordinates 78 of the semiconductor wafer W in FIG. 6 by the amount of movement when the semiconductor wafer W is moved from the temporary placement table 24 to the chuck table 52 are shown.

  Then, based on the difference between the coordinate 80 of the mounting surface center of the spinner cleaning table 41 and the coordinate 78 of the wafer center of the semiconductor wafer W by the control unit 19, the amount of movement in the front-rear direction of the rotation shaft 31 of the wafer recovery unit 18. And the amount of rotation and the amount of expansion / contraction of the telescopic arm 32 are calculated. Similar to the wafer supply unit 17, the wafer recovery unit 18 is controlled according to the calculation result of the control unit 19, and the wafer center of the semiconductor wafer W is aligned with the mounting surface center of the spinner cleaning table 41 so that the spinner cleaning table 41. Placed on.

  As described above, when the center of the processed semiconductor wafer W is accurately aligned with the center of the mounting surface of the spinner cleaning table 41, the semiconductor wafer W is eccentrically rotated at a high speed with respect to the spinner cleaning table 41. There is no. Further, when the semiconductor wafer W is placed on the spinner cleaning table 41, the suction surface 42a is not exposed, and the suction of the cleaning water to the suction source through the exposed suction surface 42a is suppressed. .

  With reference to FIG. 9, the flow of the grinding operation by the grinding apparatus will be described. FIG. 9 is an operation flow of the grinding operation by the grinding apparatus.

  As shown in FIG. 9, the semiconductor wafer W before processing is taken out from the cassette 2 by the loading / unloading arm 14 and temporarily placed on the temporary placement table 24 (step S01). Next, the semiconductor wafer W is imaged by the imaging unit 25, and the captured image data is output to the control unit 19 (step S02). Next, based on the image data input by the control unit 19, the inner peripheral edge center of the semiconductor wafer W and the coordinates of the wafer center are calculated (step S03).

  Next, based on the calculated coordinates of the center of the inner periphery of the semiconductor wafer W and the coordinates of the center of the holding surface of the chuck table 52 stored in advance, the center of the inner periphery of the semiconductor wafer W is chucked by the wafer supply unit 17. The semiconductor wafer W is placed on the chuck table 52 so as to coincide with the center of the holding surface 52 (step S04). Next, the turntable 53 is rotated 120 degrees, the semiconductor wafer W placed on the chuck table 52 is moved to the rough grinding position, and the roughing unit 45 rough-grinds the reinforcing convex portion 98 of the semiconductor wafer W. (Step S05). Next, the turntable 53 is further rotated by 120 degrees, the semiconductor wafer W placed on the chuck table 52 is moved to the finish grinding position, and the reinforcing convex portion 98 of the semiconductor wafer W is finish ground by the finish grinding unit 46. (Step S06).

  Next, the turntable 53 is rotated 120 degrees and the semiconductor wafer W placed on the chuck table 52 is moved to the wafer replacement position (step S07). Next, based on the calculated coordinates of the wafer center of the semiconductor wafer W and the coordinates of the center of the mounting surface of the spinner cleaning table 41 stored in advance, the wafer recovery unit 18 moves the wafer center of the semiconductor wafer W to the spinner cleaning table 41. The semiconductor wafer W is placed on the spinner cleaning table 41 so as to coincide with the center of the placement surface (step S08). Next, the semiconductor wafer W is spinner cleaned on the spinner cleaning table 41 (step S09), and the semiconductor wafer W after cleaning is stored in the cassette 2 from the spinner cleaning table 41 by the loading / unloading arm.

  As described above, according to the alignment mechanism according to the present embodiment, the coordinates of the center of the inner peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W are calculated, and the calculated coordinates of the center of the inner peripheral edge are stored. Since the semiconductor wafer W is placed on the chuck table 52 based on the coordinates of the holding surface center of the chuck table 52, the inner peripheral edge center of the semiconductor wafer W is accurately aligned with the holding surface center of the chuck table 52. It becomes possible to do.

  Next, a second embodiment of the present invention will be described. The alignment mechanism according to the second embodiment of the present invention is different from the alignment mechanism according to the first embodiment described above only in that an image is captured while the semiconductor wafer is held on the wafer supply unit. Therefore, only the differences will be particularly described. FIG. 10 is a partially enlarged view of the wafer supply unit according to the second embodiment of the present invention.

  As shown in FIG. 10, the wafer supply unit 90 includes a holding mechanism 81 instead of the suction holding unit 33 described in the first embodiment. The holding mechanism 81 includes three holding rollers 82 that hold the outer peripheral edge of the semiconductor wafer W, and a roller moving unit 83 that moves each holding roller 82 in the radial direction. The roller moving portion 83 is supported at the tip of the telescopic arm 91 via the flange portion 84, and the rotation plate 85 rotatably provided on the flange portion 84 and the rotation of the rotation plate 85 are linearly moved. It has three links 86 and a support plate 87 which are converted into the above and transmitted to each holding roller 82.

  Each holding roller 82 has an outer peripheral surface in contact with the semiconductor wafer W formed in a V shape by two upper and lower tapered surfaces. The outer peripheral surface of the holding roller 82 is formed of a low friction material such as a fluororesin. The support plate 87 has a disk shape whose outer shape is larger than that of the semiconductor wafer W, and is formed with three long holes 87a extending in the radial direction at equal intervals in the circumferential direction. In the elongated hole 87a, a support shaft (not shown) protruding from the upper surface of the holding roller 82 is inserted from below to restrict the moving direction of the holding roller 82 in the radial direction.

  Each link 86 is a linear plate member, and one end is rotatably connected to the support shaft of the holding roller 82 and the other end is rotatably connected to the rotation plate 85. The rotating plate 85 has a disk part 85a and three arm parts 85b extending from the disk part 85a in the radial direction at equal intervals in the circumferential direction. The disk portion 85a is rotatably supported by the flange portion 84, and the tip of each arm portion 85b is rotatably connected to each link 86. The rotation plate 85 is connected to a drive unit (not shown) and is rotated by driving of the drive unit.

  In the initial state where the holding mechanism 81 does not hold the semiconductor wafer W, the arm portion 85b of the rotation plate 85 and the link 86 are in a straight line, and the holding roller 82 is positioned radially outward. When the rotation plate 85 is rotated from this initial state, the rotation of the rotation plate 85 is converted into a linear movement by the long hole 87a of the link 86 and the support plate 87, and the holding roller 82 moves radially inward. Thus, the semiconductor wafer W can be held.

  Further, an imaging unit 89 is provided on the upper surface of the support plate 87, and imaging can be performed with the semiconductor wafer W held by the holding mechanism 81 by the imaging unit 89. In addition, a long hole 87b for the imaging unit 89 is formed in the support plate 87, and the imaging position of the imaging unit 89 can be adjusted by the long hole 87b.

  As described above, according to the alignment mechanism according to the present embodiment, since the imaging unit 89 is provided in the wafer supply unit 90, the semiconductor wafer W can be supplied to the chuck table 52 while imaging. Therefore, it is possible to increase the supply speed of the semiconductor wafer W to the chuck table 52 in the grinding apparatus 1.

  In each of the above-described embodiments, the imaging convexities 98 of the semiconductor wafer W are imaged by the imaging units 25 and 89, and arbitrary three points are extracted from the image data of the reinforcing convexity 98 and detected. Although configured, it is not limited to this configuration. Any configuration that detects any three points from the inner peripheral edge and the outer peripheral edge of the semiconductor wafer W may be used, and an optical detection may be employed. For example, as shown in FIG. 11, by using a reflective photosensor 92 in which a light emitting element 93 and a light receiving element 94 are arranged side by side, from the inner peripheral edge and the outer peripheral edge of the reinforcing convex portion 98 of the semiconductor wafer W. Any three points are detected.

  In each of the above embodiments, the movement of the wafer supply units 17 and 90 is controlled to align the center of the inner peripheral edge of the semiconductor wafer W with the wafer center of the chuck table 52. It is not limited. As long as the configuration is such that the center of the inner peripheral edge of the semiconductor wafer W is calculated and aligned based on the center of the inner peripheral edge and the wafer center of the chuck table 52 stored in advance in the control unit 19. Also good. For example, the position may be adjusted on the temporary placement table 24 or the chuck table 52.

  In each of the above-described embodiments, the inner peripheral edge and the outer peripheral edge of the semiconductor wafer W are simultaneously imaged, but may be separately imaged. Further, if the amount of eccentricity between the center of the inner periphery of the semiconductor wafer W and the center of the wafer is small, only the inner periphery of the semiconductor wafer W is imaged and the center of the inner periphery of the semiconductor wafer W and the center of the wafer are calculated. Good.

  In each of the above-described embodiments, only one location is imaged and the center of the inner peripheral edge of the semiconductor wafer W and the wafer center are calculated. However, a plurality of locations may be imaged. Thereby, since the inner peripheral edge center and the wafer center of the semiconductor wafer W are calculated based on the image data picked up at a plurality of places, the calculation accuracy can be improved.

  In each of the above embodiments, the control unit 19 detects any three points of the inner and outer peripheral edges of the semiconductor wafer W to calculate the inner peripheral edge center and the wafer center of the semiconductor wafer W. However, it is not limited to this configuration. Any calculation method may be used as long as the center of the inner peripheral edge of the semiconductor wafer W can be calculated. For example, two points are detected from the curves of the inner peripheral edge and the outer peripheral edge obtained from the image data, and the intersections of the normals to the curves from the two points are defined as the inner peripheral edge center and the wafer center of the semiconductor wafer W, respectively. It is also possible to do.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  As described above, the present invention can accurately align the center of the inner peripheral edge of the reinforcing convex portion with the center of the holding table in the workpiece in which the reinforcing convex portion is formed in the disk-shaped outer peripheral region. It has an effect and is particularly useful for a positioning mechanism, a grinding apparatus, a positioning method and a grinding method for grinding a semiconductor wafer.

It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is an external appearance perspective view of the semiconductor wafer before a process. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is an external appearance perspective view of a grinding device. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is the elements on larger scale of a grinding device. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is explanatory drawing of the imaging process of the semiconductor wafer by an imaging part. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is the image data imaged by the imaging part. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is explanatory drawing of the alignment process of the semiconductor wafer with respect to a chuck table. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is a figure which shows the detection state by a contact-type sensor. It is a figure which shows 1st Embodiment of the grinding device which concerns on this invention, and is explanatory drawing of the alignment process of the semiconductor wafer with respect to a spinner cleaning table. It is a figure showing a 1st embodiment of a grinding device concerning the present invention, and is an operation flow of grinding operation by a grinding device. It is a figure which shows 2nd Embodiment of the grinding device which concerns on this invention, and is the elements on larger scale of a wafer supply part. It is a figure which shows the modification of the grinding apparatus which concerns on this invention.

Explanation of symbols

1 Grinding equipment 4 Loading / unloading unit (positioning mechanism)
5 Convex removal unit (grinding mechanism)
15 Temporary placement section 16 Spinner cleaning section 17 Wafer supply section (positioning placement section)
18 Wafer recovery unit (mounting unit for cleaning)
19 control unit (inner peripheral edge position data acquisition unit, inner peripheral edge center position data calculation unit, holding surface center position data storage unit, alignment mounting unit, mounting surface center position data storage unit, cleaning mounting unit)
24 Temporary placement table 25 Imaging unit (inner peripheral edge position data acquisition unit)
Reference Signs List 31 Rotating shaft 32 Telescopic arm 41 Spinner cleaning table 42 Placement surface 42a Suction surface 45 Rough grinding unit 46 Grinding unit 52 Chuck table (holding table)
DESCRIPTION OF SYMBOLS 56 Holding surface 56a Adsorption surface 58 Contact sensor 61, 62 Contactor 73 Grinding wheel 96 Device formation area 97 Outer periphery area 98 Reinforcement convex part W Semiconductor wafer (workpiece)

Claims (8)

A device forming region where a device is formed on the front surface and an outer peripheral region around the device forming region; removing a region corresponding to the device forming region on the back surface; from a region corresponding to the outer peripheral region on the back surface An inner peripheral edge position data acquisition unit for acquiring position data of the inner peripheral edge of the reinforcing convex part of the workpiece formed so that the reinforcing convex part protrudes;
Based on the position data of the inner peripheral edge portion of the reinforcing convex portion, the inner peripheral edge center that calculates the position data of the inner peripheral edge center indicating the center of the inner periphery defined in the inner peripheral edge portion of the reinforcing convex portion A position data calculation unit;
A holding surface center position data storage unit that stores position data of the holding surface center indicating the center of the holding surface of the holding table that holds the workpiece;
Based on the position data of the center of the inner periphery and the position data of the center of the holding surface, the center of the inner periphery is aligned with the center of the holding surface, and the positioning is performed to place the workpiece on the holding surface. An alignment mechanism comprising a mounting portion. A temporary placement table capable of rotating in a state where the workpiece is temporarily placed;
The alignment mechanism according to claim 1, wherein the inner peripheral edge position data acquisition unit acquires position data of an inner peripheral edge of the reinforcing convex portion by rotating the temporary placement table.   The inner peripheral edge center position data calculation unit extracts the three points from the position data of the inner peripheral edge of the reinforcing convex portion, and sets the points A, B, and C as the points A, B, and C. The intersection of the perpendicular bisector of the line segment connecting the line A and the perpendicular bisector of the line segment connecting the points A and C is calculated as position data of the center of the inner peripheral edge. Item 3. The alignment mechanism according to item 1 or 2.   The inner peripheral edge position data acquisition unit images the inner peripheral edge of the reinforcing convex part, and acquires image data obtained by imaging as position data of the inner peripheral edge of the reinforcing convex part. The alignment mechanism according to any one of claims 1 to 3, wherein the alignment mechanism is characterized.   5. The positioning mechanism according to claim 1, and a grinding mechanism that grinds the reinforcing convex portion of the workpiece in a state in which the center of the inner peripheral edge is aligned with the center of the holding surface. Grinding equipment. A spinner cleaning table for performing spinner cleaning of the ground workpiece, the mounting surface having a ground workpiece on which the reinforcing convex portion is ground by the grinding mechanism;
A cleaning mounting section for mounting the ground workpiece from a holding surface of the holding table on a mounting surface of the spinner cleaning table;
A placement surface center position data storage unit that stores placement surface center position data indicating the center of the placement surface;
The inner peripheral edge position data acquisition unit acquires the position data of the outer peripheral edge of the reinforcing convex part together with the position data of the inner peripheral edge of the reinforcing convex part,
The inner peripheral edge center position data calculation unit calculates the position data of the work center indicating the center of the work based on the position data of the outer peripheral edge of the reinforcing convex portion together with the position data of the inner peripheral edge center. And
The cleaning mounting portion aligns the workpiece center with the placement surface center based on the workpiece center position data and the placement surface center position data, and the workpiece is placed on the placement surface. The grinding apparatus according to claim 5, wherein the grinding apparatus is mounted on the grinding machine. A device forming region where a device is formed on the front surface and an outer peripheral region around the device forming region; removing a region corresponding to the device forming region on the back surface; from a region corresponding to the outer peripheral region on the back surface Obtaining position data of the inner peripheral edge of the reinforcing convex portion from a workpiece formed so that the reinforcing convex portion protrudes;
Based on the position data of the inner peripheral edge portion of the reinforcing convex portion, calculating position data of the inner peripheral edge center indicating the center of the inner periphery defined in the inner peripheral edge portion of the reinforcing convex portion;
Based on the position data of the holding surface center indicating the center of the holding surface of the holding table that holds the workpiece stored in advance and the position data of the inner peripheral edge center, the inner peripheral edge center is aligned with the holding surface center. And a step of placing the workpiece on the holding surface.   Each step of the alignment method according to claim 7, and a step of grinding the reinforcing convex portion of the workpiece in a state where the center of the inner peripheral edge is aligned with the center of the holding surface. Grinding method.

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