JP2008124292A - Wafer positioning jig of processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jig for appropriately adjusting a wafer position with respect to a holding surface of a chuck table and facilitating an operation of correctly shifting the center of the wafer from the center of a recess formed on the rear face (the center of rotation of the chuck table) by a desired amount of eccentricity. <P>SOLUTION: The jig 90 detachably mounted on a table part 36 of the chuck table includes an annular frame 93 movably fitted over in an arbitrarily radial direction of the table part 36 and having a wafer fitting hole 91a into which the wafer 1 mounted on the chuck table 30 can be fitted in this state, and a screw 94 and a nut 95 for adjusting the position of the frame 93 and detachably fixing the frame 93 to the table part 36. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wafer position adjusting jig of a processing apparatus suitable for positioning a wafer on a chuck table such as a grinding apparatus.

  A semiconductor chip of a device used for various electronic devices generally has a rectangular rectangular area defined by dividing lines called streets on the surface of a disk-shaped semiconductor wafer, and an electronic circuit is formed on the surface of these areas. Then, it is manufactured by a method in which the back surface is ground and thinned and divided along the street. By the way, downsizing and thinning of electronic devices in recent years are remarkable, and accordingly, a semiconductor chip is required to be thinner, which means that it is necessary to make the semiconductor wafer thinner than before.

  However, when the semiconductor wafer is thinned, the rigidity is lowered, so that there is a problem that handling in the subsequent process becomes difficult or breakage is likely to occur. Therefore, at the time of back surface grinding, only the portion corresponding to the circular device formation region on which the semiconductor chip is formed on the surface is ground and thinned to the required thickness, and at the same time, the surrounding annular peripheral region is relatively By leaving it as a thick reinforcing portion, the above-mentioned problem due to thinning is prevented from occurring. Techniques for forming the concave portion on the back surface with the outer peripheral portion being thick as described above are disclosed in, for example, Patent Documents 1 and 2.

  In order to form a recess on the back surface of such a wafer, a grindstone was formed in an annular shape while rotating the wafer while adsorbing and holding the wafer with the back surface exposed on a rotatable chuck table. There is a method of pressing a cup-shaped grindstone tool against the work surface. In this method, the diameter of the grindstone is approximately equal to the radius of the semiconductor wafer (equal to the radius of the diameter of the recess to be formed), the cutting edge passes through the rotation center of the wafer, and the outer peripheral edge of the cutting edge is outside the recess. By facing the wafer so as to pass through the periphery, only the portion corresponding to the device formation region is ground, leaving the outer peripheral portion.

JP 2004-281551 A JP 2005-123425 A

  By the way, on the outer peripheral edge of the semiconductor wafer, as a mark indicating the crystal orientation of the semiconductor, a V-shaped notch called a notch or a part of the outer peripheral edge called an orientation flat is cut linearly along the tangential direction. What was formed is formed. When the concave portion is formed on the back surface as described above, it is necessary to avoid the crystal orientation mark in order to ensure the strength of the wafer. Therefore, the concave portion is eccentric with respect to the wafer. Actually, the center of the recess is located on the opposite side of the crystal orientation mark with respect to the center of the wafer, and the width of the outer peripheral portion where the original thickness remains and becomes the annular protrusion is around the crystal orientation mark. The position at 180 ° from the crystal orientation mark is the smallest.

  Since the recess formed on the back surface of the wafer is concentric with the rotation center of the rotating chuck table, it is necessary to decenter the wafer with respect to the rotation center of the chuck table in order to decenter the recess with respect to the wafer as described above. There is. However, it is difficult to position the wafer at a position corresponding to the eccentric amount (deviation amount) of the recess set with respect to the chuck table, and the wafer is supplied to the chuck table by an automatic conveyance mechanism. In the processing equipment for back grinding, the automation has been hindered.

  Therefore, according to the present invention, the position of the wafer with respect to the holding surface of the chuck table can be adjusted appropriately, whereby the center of the wafer can be accurately adjusted from the center of the recess formed on the back surface (the center of rotation of the chuck table) to a desired amount of eccentricity. It is an object of the present invention to provide a wafer position adjusting jig for a processing apparatus that can facilitate the operation of shifting to a position.

  The present invention includes a circular frame having a circular wafer holding surface that has a diameter larger than that of a disk-shaped wafer having a device formed on the surface thereof, and sucks and holds the wafer. A wafer holding means to be rotated, a processing wheel provided with an annular processing member provided in a state where the processing surface faces the wafer holding surface of the wafer holding means in parallel, the processing wheel is rotated, and the wafer holding means In order to position a holding position of a wafer, which is provided in a processing apparatus having a processing wheel driving means for pressing a processing member against a processing surface of the held wafer and is held in close contact with the wafer holding surface of the wafer holding means The wafer position adjusting jig is fitted to the circular frame of the wafer holding means so as to be movable along an arbitrary radial direction of the wafer holding surface. In this state, an annular frame having a wafer fitting hole into which a wafer placed on the wafer holding surface can be fitted, a radial position of the frame with respect to the frame body, and a frame body And a frame position adjusting / fixing means for detachably fixing the frame.

  According to the wafer position adjusting jig of the present invention, the frame is fitted into the frame body of the wafer holding means, and the wafer placed on the wafer holding surface is fitted into the wafer fitting hole of the frame. By adjusting the position by moving the frame in the radial direction (the direction along the wafer holding surface) by the position adjustment fixing means, the wafer moves integrally with the frame and the radial position is adjusted in the same direction. After the wafer is positioned with respect to the wafer holding surface, the frame is fixed to the frame body by the frame position adjustment fixing means, whereby the wafer is fixed to the frame body, that is, the wafer holding means. By adjusting the position of the frame, the center of the wafer can be accurately displaced with respect to the rotation center of the holding means. Therefore, it is extremely useful as wafer positioning when forming an eccentric recess on the back surface of the wafer while avoiding the crystal orientation mark. . After the positioning of the wafer is completed, the wafer can be sucked and held on the wafer holding surface, the jig can be removed from the wafer holding means, and the back surface of the wafer can be processed by the processing wheel.

  The frame position adjusting / fixing means according to the present invention preferably includes an elastic mechanism that elastically contacts the frame with the frame of the holding means. According to this aspect, even when there is a variation in the outer diameter of the frame of the wafer holding means into which the frame is fitted, the elastic mechanism absorbs the variation, and the wafer position with respect to the rotation center of the wafer holding means is kept constant. can do.

  According to the present invention, the position of the wafer relative to the holding surface of the holding means such as the chuck table can be adjusted as appropriate, so that the center of the wafer is separated from the center of the recess formed on the back surface (rotation center of the chuck table). There is an effect that the operation of accurately shifting the desired amount of eccentricity can be facilitated.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Semiconductor Wafer Reference numeral 1 in FIG. 1 shows an example of a disk-shaped semiconductor wafer (hereinafter abbreviated as a wafer) whose back surface is ground and thinned by a grinding apparatus according to an embodiment. The wafer 1 is a silicon wafer or the like, and the thickness before processing is, for example, about 800 μm. A plurality of rectangular semiconductor chips (devices) 3 are partitioned on the surface of the wafer 1 by grid-like division lines 2. An electronic circuit (not shown) such as an IC or an LSI is formed on the surface of the semiconductor chip 3.

  The plurality of semiconductor chips 3 are formed in a substantially circular device formation region 4 concentric with the wafer 1. The device forming region 4 occupies most of the wafer 1, and the outer peripheral portion of the wafer around the device forming region 4 is an annular outer peripheral region 5 in which the semiconductor chip 3 is not formed. A V-shaped notch 6a indicating the crystal orientation of the semiconductor is formed at a predetermined location on the peripheral surface of the wafer 1. This notch 6 a is formed in the outer peripheral surplus region 5. The wafer 1 is finally cut and divided along the planned division line 2 and separated into a plurality of semiconductor chips 3. The grinding technique according to the present embodiment thins the region by grinding only the region corresponding to the device formation region 4 on the back surface of the wafer 1 before the semiconductor chip 3 is singulated. This is a method of forming a recess.

  When the wafer 1 is ground on the back surface, a protective tape 7 is attached to the surface on which the electronic circuit is formed as shown in FIG. 1 for the purpose of protecting the electronic circuit. The protective tape 7 has a structure in which an adhesive of about 5 to 20 μm is applied to one side of a soft resin base sheet such as polyolefin having a thickness of about 70 to 200 μm, and the adhesive is applied to the back surface of the wafer 1. It is pasted together.

[2] Configuration of Wafer Grinding Device Next, the wafer grinding device of one embodiment will be described.
FIG. 2 shows the entire wafer grinding apparatus 10, and the wafer grinding apparatus 10 includes a rectangular parallelepiped base 11 whose upper surface is horizontal. In FIG. 2, the longitudinal direction of the base 11, the horizontal width direction perpendicular to the longitudinal direction, and the vertical direction are indicated by a Y direction, an X direction, and a Z direction, respectively. At one end in the Y direction of the base 11, a pair of columns 12 and 13 are erected in the X direction (here, the left and right direction). On the base 11, a processing area 11A for grinding the wafer is provided on the side of the columns 12 and 13 in the Y direction, and the wafer before processing is supplied to the processing area 11A on the side opposite to the columns 12 and 13, In addition, an attachment / detachment area 11B for collecting the processed wafer is provided.

  In the processing area 11A, a disk-shaped turntable 20 whose rotation axis is parallel to the Z direction and whose upper surface is horizontal is rotatably provided. The turntable 20 is rotated in the direction of arrow R by a rotation drive mechanism (not shown). A plurality of disk-shaped chuck tables 30 whose rotation axis is parallel to the Z direction and whose upper surface is horizontal are arranged on the outer periphery of the turntable 20 so as to be rotatable at equal intervals in the circumferential direction. .

  These chuck tables 30 are of a generally known vacuum chuck type, and suck and hold a wafer placed on the upper surface. As shown in FIGS. 3 and 4, each chuck table 30 in this case has a configuration in which a circular adsorption area 32 made of a porous ceramic material is provided at the center of the upper surface of a disk-shaped frame 31. . An annular upper surface 31a of the frame 31 is formed around the suction area 32, and the upper surface 31a and the upper surface 32a of the suction area 32 are both horizontal and flat on the same plane (chuck table upper surface 30A). There is no. Each chuck table 30 is independently rotated or rotated in one direction or both directions by a rotation drive mechanism (not shown) provided in the turntable 20, and revolves when the turntable 20 rotates. It becomes a state.

  As shown in FIG. 2, in the state where two chuck tables 30 are arranged in the X direction on the columns 12 and 13 side, the rough grinding unit 40 </ b> A is disposed immediately above the chuck table 30 in order from the upstream side in the rotation direction of the turntable 20. And a finish grinding unit 40B. Each chuck table 30 is intermittently rotated by the turntable 20 so that the rough grinding position below the rough grinding unit 40A, the finish grinding position below the finish grinding unit 40B, and the attachment / detachment closest to the attachment / detachment area 11B. Each of the three positions is positioned.

  The rough grinding unit 40A and the finish grinding unit 40B are respectively attached to columns (rough grinding side column 12 and finish grinding side column 13). The mounting structures of the rough grinding unit 40A and the finish grinding unit 40B with respect to the columns 12 and 13 are the same and are symmetrical in the X direction. Hereinafter, the mounting structure will be described with reference to FIGS. 2 and 5 (rough grinding side mounting structure).

  The front surfaces 12a and 13a facing the processing area 11A of the columns 12 and 13 are perpendicular to the top surface of the base 11, but the back side (anti-removable area) from the center in the X direction toward the end. 11B side) and is formed on a tapered surface that is inclined obliquely at a predetermined angle. The horizontal direction, that is, the taper direction, of the tapered surface 12a of the column 12 on the rough grinding side is set to a plane parallel to a line connecting the rotation center of the chuck table 30 and the rotation center of the turntable 20 positioned at the rough grinding position. Yes. On the other hand, the taper direction of the tapered surface 13a of the column 13 on the finish grinding side is set to a surface parallel to a line connecting the rotation center of the chuck table 30 and the rotation center of the turntable 20 positioned at the finish grinding position. . An X-axis slider 55 is attached to each of the tapered surfaces 12 a and 13 a via an X-axis feed mechanism 50, and a Z-axis slider 65 is attached to the X-axis slider 55 via a Z-axis feed mechanism 60. ing.

  The X-axis feed mechanism 50 includes a pair of upper and lower guide rails 51 fixed to the tapered surfaces 12a and 13a, and screws (not shown) that are arranged between the guide rails 51 and screwed into and penetrate the X-axis slider 55. It is comprised from the rod and the motor 53 which rotates this screw rod forward / reversely. Both the guide rail 51 and the threaded rod extend in parallel with the taper direction of the tapered surfaces 12 a and 13 a, and the X-axis slider 55 is slidably mounted on the guide rail 51. The X-axis slider 55 is adapted to reciprocate along the guide rail 51 as the power of the screw rod rotated by the motor 53 is transmitted. The reciprocating direction of the X-axis slider 55 is parallel to the extending direction of the guide rail 51, that is, the taper direction of the tapered surfaces 12a and 13a.

  The front surface of the X-axis slider 55 is a surface along the X / Z direction, and a Z-axis feed mechanism 60 is provided on the front surface. The Z-axis feed mechanism 60 has a configuration in which the feed direction of the X-axis feed mechanism 50 is changed to the Z direction, and a pair of left and right guide rails 61 extending in the Z direction fixed to the front surface of the X axis slider 55; A screw rod 62 that extends between the guide rails 61 and extends in the Z direction that is threadedly engaged with the Z-axis slider 65 and a motor 63 that rotates the screw rod 62 forward and backward. The Z-axis slider 65 is slidably mounted on the guide rail 61 and is moved up and down along the guide rail 61 by the power of the screw rod 62 rotated by the motor 63.

  A rough grinding unit 40A shown in FIG. 3 is fixed to the Z-axis slider 65 attached to the rough grinding side column 12. The finish grinding shown in FIG. 4 is attached to the Z axis slider 65 attached to the finish grinding side column 13. The unit 40B is fixed. The grinding units 40A and 40B have the same configuration, and a cylindrical spindle housing 41 whose axial direction extends in the Z direction, and a spindle shaft 42 coaxially and rotatably supported in the spindle housing 41. The motor 43 is fixed to the upper end of the spindle housing 41 and rotationally drives the spindle shaft 42, and the disk-shaped flange 44 is coaxially fixed to the lower end of the spindle shaft 42.

  The difference between the rough grinding unit 40 </ b> A and the finish grinding unit 40 </ b> B resides in a grindstone wheel attached to the flange 44. That is, a rough grinding wheel 45 is attached to the rough grinding unit 40A, and a finish grinding wheel 46 is attached to the finish grinding unit 40B. These grindstone wheels 45 and 46 also have the same basic configuration, and as shown in FIGS. 3 and 4, the entire circumference of the outer peripheral portion of the lower end surface is formed on the lower end surface of the annular frame 47 having a conical bottom surface. A plurality of grinding wheels for rough grinding (a grinding wheel 45a on the rough grinding wheel wheel 45 side and a grinding wheel 46a on the finish grinding wheel wheel 46 side) are annularly arranged and fixed. Each grindstone wheel 45, 46 is detachably attached to the flange 44 by means of screws 47 or the like.

  As each of the grindstones 45a and 46a, for example, a vitreous sintered material called vitrified mixed with diamond abrasive grains and fired is used. The difference between the rough grinding wheel 45 and the finishing grinding wheel 46 is in the grain size of each grinding wheel 45a, 46a, strictly the grain size of the abrasive grains contained in the grinding wheel. As the rough grinding wheel 45a, for example, those containing # 320 to # 400 abrasive grains are used, and as the finishing grindstone 46a, for example, those containing # 2000 to # 8000 abrasive grains are used. Each grindstone 45a, 46a is formed in the cyclic | annular form of the same diameter, The width | variety is constant with 2-4 mm, for example.

  In each of the grinding wheel 45, 46, the outer diameter of each of the grinding wheels 45a, 46a is a substantially effective grinding diameter. The grinding outer diameter is the same for each of the grinding wheels 45a, 46a, and the radius of the wafer 1 is the same. Set to be equivalent. Strictly speaking, the device of the wafer 1 in which the cutting edge, which is the lower end surface of the grindstones 45a, 46a, passes over the center of the rotating chuck table 30, and the outer peripheral edge of the cutting edge is adsorbed and held by the chuck table 30. 6 passes through the outer peripheral edge of the formation region 4 (the boundary between the device formation region 4 and the outer peripheral surplus region 5), and only the region corresponding to the device formation region 4 is ground, so that the recess 8 shown in FIG. It is set so that it can be formed. That is, as a matter of course, the outer diameters of the grindstones 45 a and 46 a are the same as the radius of the recess 8 to be formed on the back surface of the wafer 1. In addition, as for the grindstone 46a for finishing, when it is desired to finish-grind the inner peripheral side surface 5a (see FIG. 6B) of the concave portion 8 formed, the outer diameter of the grindstone 46a is set to a dimension capable of that.

  In the rough grinding unit 40A, the rotation center of the rough grinding wheel 45 (the axis of the spindle shaft 42) is directly above the line connecting the rotation center of the chuck table 30 positioned at the rough grinding position and the rotation center of the turntable 20. The position is set so as to exist. The coarse grinding unit 40A is reciprocated along the taper direction of the taper surface 12a of the column 12 together with the Z-axis slider 65 by the X-axis direction feed mechanism 50. Therefore, during the reciprocal movement, the rotation center of the rough grinding wheel 45 reciprocates directly above the line connecting the rotation center of the chuck table 30 positioned at the rough grinding position and the rotation center of the turntable 20. It is like that. Hereinafter, since the reciprocating direction is the direction between the axes of the chuck table 30 and the turntable 20, it is referred to as an “interaxial direction”.

  The position setting is the same on the side of the finish grinding unit 40B. The rotation center of the finish grinding wheel 44 of the finish grinding unit 40B is the rotation center of the chuck table 30 and the rotation center of the turntable 20 positioned at the finish grinding position. When the finish grinding unit 40B reciprocates along the taper direction of the taper surface 13a of the column 13 together with the Z-axis slider 65 and the X-axis slider 55, a finish grinding wheel is provided. The rotation center 46 is reciprocally moved along the direction of the line, that is, the direction between the axes, directly above the line connecting the rotation center of the chuck table 30 and the rotation center of the turntable 20 positioned at the finish grinding position. It has become.

  As shown in FIG. 2, a thickness measurement gauge 25 for measuring the thickness of the wafer on the chuck table 30 positioned at the rough grinding position and the finish grinding position is disposed on the base 11. As shown in FIGS. 3A and 4A, these thickness measurement gauges 25 are constituted by a combination of a reference side height gauge 26 and a wafer side height gauge 27. The reference height gauge 26 detects the height position of the chuck table upper surface 30A by contacting the upper end 31a of the frame 31 of the chuck table 30 where the tip of the swinging reference probe 26a is not covered with the wafer.

  The wafer-side height gauge 27 detects the height position of the upper surface of the wafer when the tip of the oscillating variable probe 27 a contacts the upper surface of the wafer held by the chuck table 30, that is, the surface to be processed. According to the thickness measurement gauge 25, the thickness of the wafer is measured based on the value obtained by subtracting the measurement value of the reference height gauge 26 from the measurement value of the wafer height gauge 27. If the wafer is ground to the target thickness: t1, the original thickness: t2 is first measured before grinding, and (t2-t1) is taken as the grinding amount. The wafer thickness measurement point where the variation probe 27a of the wafer side height gauge 27 contacts is the outer peripheral edge of the wafer 1 (outside the device formation region 4) as shown by the broken lines in FIGS. 3 (a) and 4 (a). The outer peripheral part close to the (periphery) is suitable.

The above is the configuration related to the processing area 11A on the base 11, and the detachable area 11B will be described with reference to FIG.
In the center of the detachable area 11B, a two-bar link pickup robot 70 that moves up and down is installed. Around the pickup robot 70, a supply cassette 71, an alignment table 72, a supply arm 73, a recovery arm 74, a spinner type cleaning device 75, and a recovery cassette 76 are arranged counterclockwise as viewed from above. ing.

  The cassette 71, the alignment table 72, and the supply arm 73 are means for supplying the wafer to the chuck table 30. The collection arm 74, the cleaning device 75, and the cassette 76 collect the wafer after the back surface grinding from the chuck table 30. It is a means for moving to the next process. The cassettes 71 and 76 accommodate a plurality of wafers in a horizontal posture and in a stacked state at a constant interval in the vertical direction, and are set at predetermined positions on the base 11.

  When one wafer is taken out from the supply cassette 71 by the pick-up robot 70, the wafer is placed on the alignment table 72 with the back side to which the protective tape 7 is not attached facing upward. It is determined at a certain position. Next, the wafer is picked up from the alignment table 72 by the supply arm 73 and placed on the chuck table 30 waiting at the attachment / detachment position.

  On the other hand, the back surface is ground by each of the grinding units 40A and 40B, and the wafer on the chuck table 30 positioned at the attachment / detachment position is taken up by the recovery arm 74, transferred to the cleaning device 75, washed with water and dried. The wafer cleaned by the cleaning device 75 is transferred and stored in the collection cassette 76 by the pickup robot 70.

  The positioning table 72 includes a central rotary table 72a and a plurality of pins 72b that are arranged radially around the rotary table 72a and advance and retract with respect to the center of the rotary table 72a. The wafer 1 is placed on the rotary table 72a by the pickup robot 70 with the back side facing up. When a plurality of pins 72b that have been retreated to the periphery move to the rotary table 72a, the wafer 1 is pushed by the pins 72b and is turned on the rotary table. The position on 72a is adjusted and positioned at a predetermined position.

  A crystal orientation sensor 72c for detecting a crystal orientation mark (notch 6a in the example of FIG. 1) formed on the wafer 1 is disposed on a predetermined position around the alignment table 72 on the base 11. . As the crystal orientation sensor 72c, a transmission type or reflection type optical sensor composed of a combination of a light emitting part and a light receiving part is suitably used. The notch 6a of the wafer 1 is detected by the crystal orientation sensor 72c by the rotation of the rotary table 72a to which the wafer 1 is sucked and fixed, and the rotary table 72a at the detection position or at a position further rotated by a predetermined angle from the detection position. Stops rotating. The stop position is a position where the wafer 1 is picked up by the supply arm 73.

  The wafer picking position from the turntable 72a is transferred from the supply arm 73 to the chuck table 30 at the attachment / detachment position, and then the turntable 20 is rotated to position the wafer 1 at the rough grinding position and the finish grinding position. At this time, in each of these grinding positions, as described later, it is set at a position where the recess 8 can be accurately formed on the back surface of the wafer while avoiding the notch 6a, and is always in a fixed direction.

[3] Wafer Position Adjustment Jig Next, the wafer position adjustment jig according to the present invention will be described with reference to FIGS.
First, as shown in FIG. 9, the frame 31 of the disk-shaped chuck table 30 shown here is formed with a flange 33 having a thickness of about half of the entire thickness at the lower part of the outer peripheral surface. The chuck table 30 is fixed to a chuck table base (not shown) that is rotationally driven. Fixing to the chuck table base is performed by screwing screws 35 through a plurality of screw through holes 34 formed through the flange portion 33 in the thickness direction into the chuck table base and fastening them.

  The suction area 32 of the chuck table 30 is provided in an upper table portion 36 having an outer diameter smaller than that of the flange portion 33 of the frame 31, and in this case, is divided into four concentric areas. That is, the three annular areas 32B, 32C, and 32D are partitioned from the central area 32A toward the periphery by the high-density partition portion 32b that is porous. The frame body 31 is formed with a plurality of air suction passages 37 such as grooves communicating with the lower surfaces of the areas 32A to 32D, and further communicated with the air suction passages 37 and connected to an air suction device such as a compressor. A communication passage 38 is partially formed.

  Each of the areas 32A to 32D has an outer diameter corresponding to the size of the wafer 1 such as 100 mm, 125 mm, 150 mm, and 200 mm in order from the center side. When the wafer 1 is sucked and held, the wafer 1 is placed substantially concentrically on the upper surface 32a of the suction area 32, but depending on the size, it is not covered by the wafer 1 (the minimum central area 32A is There is an area, and air suction can be stopped in the area.

  A wafer position adjusting jig (hereinafter, abbreviated as a jig) 90 according to this embodiment is detachably mounted on the table portion 36 of the chuck table 30. The jig 90 includes a frame 93 having an annular side portion 92 projecting downward from an outer peripheral edge portion of an annular flat plate portion 91 having a constant width, a screw 94 for fixing the frame 93 to the table portion 36, and And a nut 95. The hole 91a on the inner side of the flat plate portion 91 is a wafer fitting hole, and the diameter (the inner diameter of the flat plate portion 91) is substantially the same as the outer diameter of the wafer 1 to be processed. The dimensions are set so that they do not move when fitted. Further, the inner diameter of the side portion 92 of the frame 93 is set slightly larger than the outer diameter of the table portion 36, and the height of the side portion 92 (the amount of protrusion from the flat plate portion 91) is greater than the height of the table portion 36. Is set too small.

  As shown in FIG. 9, the frame 93 has the table portion 36 fitted inside the side portion 92 facing downward, and the flat plate portion 91 is placed on the upper surface of the table portion 36, that is, the chuck table upper surface 30 </ b> A. Set to In this state, since the inner diameter of the side portion 92 is slightly larger than the outer diameter of the table portion 36, the frame 93 can move in the radial direction by the amount of the gap generated between the two. Then, the wafer 1 placed on the upper surface of the table portion 36 is fitted into the fitting hole 91a, moved in the radial direction together with the frame 93, and the position in the radial direction is adjusted. As shown in FIG. 7, the side portion 92 of the frame 93 is formed with a notch 92 a that escapes from the interference of the screw 35 that fixes the chuck table 30 to the chuck table base so that the frame 93 can be normally mounted. . The frame 93 is for positioning the wafer 1, and is therefore formed of a material having sufficient strength that is difficult to deform. Examples of the material include metals, ceramics, and reinforced plastics.

  The screw 94 is a worm screw, and is screwed from the outside into a radially extending screw hole 92b formed through a plurality of portions (three in this case) equally divided in the circumferential direction of the side portion 92 and attached to the screw 94. A nut 95 regulates the screwing amount and is fixed to the frame 93. A seat surface 92c of a nut 94 parallel to the tangential direction is formed around the screw hole 92b on the outer peripheral surface of the side portion 92. The tip of the screw 94 is brought into contact with the outer peripheral surface of the table portion 36, whereby the radial position of the frame 93, that is, the jig 90 is positioned.

  The screw 94 in this case may be an ordinary screw, but it is more preferable if it has an elastic mechanism in which the tip surface that contacts the outer peripheral surface of the table portion 36 elastically contacts. It is easy to configure the elastic mechanism by providing an elastic member such as rubber at the tip of the screw 94. In addition, a plunger or the like that constantly urges a ball disposed at the tip by a compression spring such as a coil spring in the tip direction is also preferably employed.

  The flat plate portion 91 is formed with a plurality of confirmation holes 91b that allow the outer periphery of the table portion 36 to be visually confirmed from above with the frame 93 set on the chuck table 30. In this case, the confirmation hole 91b is arranged at an intermediate point between the screw holes 92b and is formed in a long hole shape extending in the tangential direction.

[4] Operation of Wafer Grinding Device The above is the configuration of the wafer grinding device 10 and the jig 90 for positioning the wafer 1 on the chuck table 30. Next, the wafer grinding device 10 grinds the back surface of the wafer 1. The operation of forming the recess 8 will be described.

(A) Processing cycle of wafer grinding apparatus First, the wafer 1 accommodated in the supply cassette 71 is placed on the rotary table 72a of the alignment table 72 with the back side facing up by the pickup robot 70. Then, the alignment table 72 is operated to position the wafer 1 at the picking position. Subsequently, the wafer 1 is placed by the supply arm 73 on the chuck table 30 that stands by at the attachment / detachment position and is operated in vacuum with the back side facing up.

  In the wafer 1, the protective tape 7 adhered to the front surface is in close contact with the chuck table upper surface 30 </ b> A (the upper surface 32 a of the suction area 32), and is sucked and held on the upper surface 30 </ b> A with the back surface exposed.

  Next, the turntable 20 rotates in the direction of the arrow R in FIG. 2, and the chuck table 30 holding the wafer 1 stops at the rough grinding position below the rough grinding unit 40A. At this time, the next chuck table 30 is positioned at the attachment / detachment position, and the wafer 1 to be ground next is set on the chuck table 30 as described above.

  The thickness measuring gauge 25 is set as described above with respect to the wafer 1 positioned at the rough grinding position so that the thickness of the wafer 1 can be measured. Then, the rough grinding unit 40A above the wafer 1 positioned at the rough grinding position is appropriately moved in the inter-axis direction by the X-axis feed mechanism 50, and the recess 8 is formed in the horizontal position of the rough grinding wheel 45. Position it where possible.

  After the coarse grinding wheel 45 is positioned in the horizontal direction with respect to the wafer 1, the wafer 1 is rotated in one direction by rotating the chuck table 30 and the coarse grinding wheel 45 is rotated at a high speed to thereby rotate the coarse grinding unit 40A. The wheel 45 is lowered by the Z-axis feed mechanism 60, and the grindstone 45 a of the rough grinding grindstone wheel 45 is pressed against the back surface of the wafer 1.

  As a result, only the region corresponding to the device formation region 5 is ground on the back surface of the wafer 1, and the grinding region becomes the concave portion 8 as shown in FIG. 6, and the outer peripheral surplus region 5 around the concave portion 8 has the original thickness. Is formed on the annular convex portion 5A. The recess 8 is formed by back grinding while the thickness of the device forming region 4 where the recess 8 is formed is measured by the thickness measuring gauge 25 one by one. In the rough grinding, the device formation region 4 is thinned to, for example, about 200 to 100 μm or about 50 μm, but in any case, the device forming region 4 is ground to a thickness that is, for example, about 20 to 40 μm thicker than the finished thickness.

  When the device formation area 4 reaches the target thickness in the rough grinding, the lowering of the rough grinding wheel 45 by the Z-axis feed mechanism 60 is stopped, and the rough grinding wheel 45 is rotated as it is for a certain period of time. The rough grinding is finished by raising 40A. In the wafer 1 after the rough grinding, as shown in FIG. 6A, grinding striations 9 a having a shape in which a large number of arcs are radially drawn from the center remain on the bottom surface 4 a of the recess 8. This grinding striation 9a is a trajectory of crushing processing by abrasive grains in the grindstone 45a, and is a mechanical damage layer including microcracks and the like. This mechanical damage layer is removed by the next finish grinding, but a new grinding streak 9b is formed in the finish grinding (see FIG. 4A).

  The wafer 1 that has been subjected to the rough grinding is transferred to a finish grinding position below the finish grinding unit 40B by rotating the turntable 20 in the R direction. The wafer 1 previously held on the chuck table 30 at the attachment / detachment position is transferred to the rough grinding position, and the wafer 1 is subjected to the rough grinding in parallel with the preceding finish grinding. Further, the wafer 1 to be processed next is set on the chuck table 30 moved to the attachment / detachment position.

  After the wafer 1 is positioned at the finish grinding position, the finish grinding unit 40B is appropriately moved in the inter-axis direction by the X-axis feed mechanism 50, and the horizontal direction of the finish grinding wheel 46 is performed in the same manner as in the rough grinding. The position is positioned at a recess forming position corresponding to the recess 8 formed by rough grinding. Also here, the recess forming position is on the outer peripheral side of the turntable 20 with respect to the rotation center of the wafer 1.

  Next, the wafer 1 is rotated in one direction by rotating the chuck table 30 and the finish grinding wheel 40 of the finish grinding unit 40B is rotated at a high speed, and the finish grinding unit 40B is lowered by the Z-axis feed mechanism 60, and the grinding wheel is rotated. 46a is pressed against the bottom surface 4a of the recess 8 formed on the back surface of the wafer 1, and the bottom surface 4a is ground. Also during the finish grinding, the thickness of the wafer 1 is measured while being measured by the thickness measuring gauge 25.

  As a result, the bottom surface 4a of the recess 8 is ground by the grindstone 46a for finish grinding. The amount of finish grinding is until the device formation region 4 reaches the thickness of the target semiconductor chip 3, and when the grinding is performed to that thickness, the lowering of the finish grinding wheel 46 by the Z-axis feed mechanism 60 is stopped and fixed. After the finish grinding wheel 46 is rotated as it is, the finish grinding unit 40B is raised to finish the finish grinding. As described above, when finishing grinding the inner peripheral side surface 5a of the annular convex portion 5A at the time of finish grinding, the outer diameter of the grindstone 46a is set to a dimension capable of this.

  Here, examples of suitable operating conditions for rough grinding and finish grinding will be given. In both the coarse grinding unit 40A and the finish grinding unit 40B, the rotational speed of the grinding wheel 45, 46 is 3000 to 5000 RPM, and the rotational speed of the chuck table 30 is 100 to 300 RPM. The lowering speed, which is the processing feed rate of the rough grinding unit 40A, is 3 to 5 μm / second, and the lowering speed of the finish grinding unit 40B is 0.3 to 1 μm / second.

  When both finish grinding and rough grinding, which have been performed in parallel, are completed, the turntable 20 is rotated in the R direction, and the wafer 1 after finish grinding is transferred to the attachment / detachment position. As a result, the subsequent wafer 1 is transferred to the rough grinding position and the finish grinding position, respectively. The wafer 1 on the chuck table 30 positioned at the attachment / detachment position is transferred to the cleaning device 75 by the recovery arm 74, and is washed and dried. The wafer 1 cleaned by the cleaning device 75 is transferred and accommodated in the collection cassette 76 by the pickup robot 70.

  The above is a cycle in which only the device forming region 4 on the back surface side of one wafer 1 is thinned to the thickness of the semiconductor chip 3 and at the same time the recess 8 is formed on the back surface. According to the wafer grinding apparatus 10 of the present embodiment, while the turntable 20 is intermittently rotated as described above, rough grinding is performed on the wafer 1 at the rough grinding position, and finish grinding is performed at the finish grinding position. By carrying out in parallel, the grinding process of the several wafer 1 is performed efficiently.

[5] Operation of Wafer Position Adjustment Jig Next, the usage method and operation of the jig 90 of this embodiment will be described. The jig 90 is used before the wafer grinding apparatus 10 that operates as described above is actually operated, and the wafer 90 is moved from the supply arm 73 to a fixed position with respect to the chuck table 30 located at the attachment / detachment position. The transfer position is adjusted in advance and determined by the following simulation operation so that 1 is transferred.

  First, the jig 90 is mounted on the table portion 36 of the chuck table 30, and the radial position (horizontal position) of the frame 93 with respect to the table portion 36 is set to a position where the recess 8 is formed at an appropriate position on the back surface of the wafer. Adjust and secure with screws 94. To adjust the position of the frame 93, first, the frame 93 is fitted into the table portion 36, the position of the frame 93 is roughly determined while looking at the outer peripheral edge of the table portion 36 visually recognized from the confirmation hole 91b, and the screw 94 is attached to the table portion 36. Tighten until contact and temporarily fix. Next, the screwing amount of the screw 94 is adjusted to finally determine the position of the frame 93, and a nut 95 is fastened to the screw 94 to fix the frame 93.

  From this state, as a simulated operation, the wafer 1 is transferred from the supply arm 73 onto the chuck table 30, and at this time, the wafer 1 does not hang on the inner peripheral portion of the flat plate portion 91 of the frame 93 and fits in the fitting hole 91 a. It is confirmed whether or not. When the wafer 1 is fitted into the fitting hole 91a, there is no need to change the setting of the apparatus, the jig 90 is removed from the chuck table 30, and the actual operation is started. On the other hand, when the transfer position to the chuck table 30 is deviated from the fitting hole 91a, it is determined that the device setting needs to be changed, and the supply arm 73 is stopped from the stop position on the chuck table 30 or from the rotary table 72a. Is adjusted, and the amount of movement of the pin 72b of the alignment table 72 is adjusted.

  The position of the wafer 1 positioned in this way corresponds to the position where the concave portion 8 is formed at the rough grinding position and the finish grinding position. The concave portion 8 formed on the back surface of the wafer is an area corresponding to the device forming area 4 and is adjusted to a circular area avoiding the notch 6a, as shown by the arc line 1a in FIG. The concave portion 8 formed on the back surface of the wafer is eccentric with respect to the wafer 1, and the center of the concave portion 8 is slightly shifted to the opposite side to the notch 6a by 180 °. Accordingly, the width of the annular convex portion 5A having the original thickness formed around the concave portion 8 by the formation of the concave portion 8 is widest in the vicinity of the notch 6a, and, for example, 2 to 3 mm is secured at a position farthest from the notch 6a. It will be the narrowest. Therefore, the wafer 1 should be positioned with the center of rotation shifted from the center of rotation of the chuck table 30 toward the notch 6a, and the position of the jig 90 is adjusted in advance based on the amount of shift.

  Incidentally, the wafer 1 shown in FIG. 1 and the like is provided with a notch 6a as a mark indicating the crystal orientation, but an orientation flat 6b shown in FIG. 10 may be adopted as the crystal orientation mark. In the wafer 1 on which such an orientation flat 6b is formed, a concave portion 8 is formed in a portion drawn by the arc line 1b that retreats from the arc line 1a while avoiding the orientation flat 6b.

  In the wafer 1 in which the orientation flat 6b is formed, the concave portion 8 formed is smaller than in the case where the notch 6a is formed, and the width of the annular convex portion 5A is, for example, about twice (for example, 4 to 4) in the vicinity of the orientation flat 6b. About 8 mm). That is, in the vicinity of the orientation flat 6b, it is desired to secure the width of the annular convex portion 5A of at least 2 to 3 mm from the portion that is most receding from the center in the radial direction. It will shift in the radial direction. In order to achieve this, the jig 90 shifts a distance corresponding to the amount the orientation flat 6b is retracted in the horizontal direction from the position where the rotation center of the chuck table 30 and the center of the wafer 1 are matched. Become.

  For example, when the diameter of the wafer 1 is 150 mm, the retraction amount by the orientation flat 6b is 10 mm, and the width of the annular convex portion 5A is 3 mm, the diameter of the concave portion 8 is 134 mm, the center of the concave portion 8 and the rotation of the chuck table 30 The wafer 1 is placed on the table unit 36 so that the centers coincide. In the present embodiment, the position of the wafer 1 relative to the chuck table 30 can be easily determined by using the jig 90 at the attachment / detachment position. In the wafer grinding apparatus 10 of the present embodiment, there are three chuck tables 30, and the wafer 1 is placed on a fixed position by a jig 90 on each chuck table 30.

  Thus, in an apparatus provided with a plurality of chuck tables 30, there may be variations in the outer diameter of the table portion 36 on which the jig 90 is mounted. Therefore, it is preferable that the screw 94 for adjusting the position of the frame 93 to the table portion 36 and fixing it is provided with an elastic mechanism in which the tip surface that contacts the outer peripheral surface of the table portion 36 elastically contacts. It is easy to configure the elastic mechanism by providing an elastic member such as rubber at the tip of the screw 94. In addition, a plunger or the like that constantly urges a ball disposed at the tip by a compression spring such as a coil spring in the tip direction is also preferably employed. If the elastic mechanism is added to the screw 94 in this way, even if the outer diameter of the table portion 36 varies, the elastic mechanism absorbs the variation, and the position of the wafer 1 relative to any chuck table 30 is determined. Can be constant.

[6] Application to Polishing Apparatus The above embodiment is an example in which the wafer position adjusting jig 90 according to the present invention is applied to the wafer grinding apparatus 10. This wafer position adjusting jig 90 is shown in FIG. The present invention can also be applied to a wafer polishing apparatus as shown. In FIG. 11, the same components as those in FIG. 2 are denoted by the same reference numerals, and will be described briefly.

  The wafer polishing apparatus 14 is for polishing and finishing the back surface of the wafer 1 ground by the grinding apparatus 10, and one column 12 is provided, and a polishing unit 80 can be moved up and down on the column 12. It is attached to. The polishing unit 60 has the same configuration as the grinding unit 30 and includes a spindle housing 31, a motor 33, and the like, and a polishing tool 81 is attached to the flange of the spindle shaft. The polishing tool 81 is made of a polishing cloth impregnated with metal oxide abrasive such as silica and polishes the bottom surface 4a of the recess 8 of the wafer 1 after finish grinding, whereby the grinding striation 9b disappears and the bottom surface 4a Is finished to a mirror surface.

  A table base 17 is provided in the processing area 11 </ b> A of the base 11 so as to be movable in the Y direction, and a rotary chuck table 30 is mounted on the table base 17. One end of bellows-shaped covers 19A and 19B is attached to both ends of the table base 17 in the moving direction. The other ends of these covers 19A and 19B are the column 12 and the inner wall surface of the pit 18 facing the column 12, respectively. Are attached to each. These covers 19 </ b> A and 19 </ b> B cover the moving path of the table base 17 and prevent the polishing dust and the like from falling on the moving path, and expand and contract as the table base 17 moves.

  In this polishing apparatus 14, the wafer 1 attracted and held by the chuck table 30 moves between the attachment / detachment position near the attachment / detachment area 11 </ b> B and the processing position below the polishing unit 80 as the table base 17 moves in the Y direction. Between them. The wafer 1 is transferred from the supply arm 73 to the chuck table 30 at the attachment / detachment position with the back surface on which the concave portion 8 is formed facing upward, held and held, and then moved to the processing position for polishing. The bottom surface 4 a of the recess 8 is polished by the unit 60. Then, the wafer 1 that has been polished and positioned at the attachment / detachment position is transported to the cleaning device 75 by the recovery arm 74 and cleaned in the same manner as in the above embodiment, and further transferred into the recovery cassette 76 by the pickup robot 70. , Housed.

  The wafer position adjusting jig 90 is also mounted on the chuck table 30 of the polishing apparatus 14 in the same manner as described for the grinding apparatus 10 so that the wafer 1 can be positioned with respect to the chuck table 30. .

It is the (a) perspective view and the (b) side view which show the structure of the wafer by which back surface grinding is carried out by one Embodiment of this invention, and a recessed part is formed. 1 is a perspective view of a wafer grinding apparatus according to an embodiment of the present invention. It is the (a) perspective view and (b) side view which show the rough grinding unit with which the apparatus is equipped. It is (a) perspective view and (b) side view which show the finish grinding unit with which the apparatus is equipped. It is a top view which shows the attachment structure and recessed part formation position of the grinding unit by the side of rough grinding of the apparatus. It is the (a) perspective view and (b) sectional view of a wafer in which a crevice was formed in the back. It is a perspective view which shows the state with which the wafer position adjustment jig which concerns on one Embodiment was mounted | worn with the chuck table. It is a top view of the wafer position adjustment jig. It is sectional drawing of the state in which the wafer position adjustment jig was mounted | worn with the chuck table. It is a wafer back surface figure which shows the area | region of the recessed part formed in a wafer back surface. 1 is a perspective view of a polishing apparatus to which a wafer position adjusting jig of one embodiment can be applied.

Explanation of symbols

1 ... Semiconductor wafer 3 ... Semiconductor chip (device)
4 ... Device forming region 8 ... Concave portion 10 ... Wafer grinding device (processing device)
14 ... Wafer polishing processing device (processing device)
30 ... chuck table (wafer holding means)
30A ... chuck table upper surface 36 ... table portion 40A ... rough grinding unit 40B ... finish grinding unit 45 ... rough grinding wheel (working wheel)
45a, 46a ... Grinding wheel (working member)
46 ... Finishing grinding wheel (processing wheel)
90 ... Wafer position adjusting jig 91a ... Wafer fitting hole 93 ... Frame 94 ... Screw (Frame position adjusting and fixing means)
95 ... Screw (Frame position adjustment fixing means)

Claims (2)

A wafer having a larger diameter than a disk-shaped wafer having a device formed on its surface and having a circular frame body having a circular wafer holding surface for sucking and holding the wafer and rotated around an axis by a rotary drive mechanism Holding means;
A processing wheel provided with an annular processing member provided in a state where the processing surface faces the wafer holding surface of the wafer holding means in parallel;
The processing apparatus includes a processing wheel driving unit that rotates the processing wheel and presses the processing member against a processing surface of the wafer held by the wafer holding unit,
A wafer position adjusting jig for positioning a wafer holding position held in close contact with the wafer holding surface of the wafer holding means;
Wafer fitting that is fitted into the frame of the wafer holding means so as to be movable along an arbitrary radial direction of the wafer holding surface, and in which the wafer placed on the wafer holding surface can be fitted. An annular frame with holes;
A wafer position adjusting jig for a processing apparatus, comprising: a frame position adjusting / fixing means that adjusts a position of the frame in the radial direction with respect to the frame and detachably fixes the frame to the frame.   2. The wafer position adjusting jig for a processing apparatus according to claim 1, wherein the frame position adjusting and fixing means includes an elastic mechanism for elastically contacting the frame with the frame body of the holding means. Ingredients.

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