JP6157229B2 - Grinding apparatus and grinding method - Google Patents

Description

  The present invention relates to a grinding apparatus and a grinding method provided with a plurality of chuck tables.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. A dividing line is cut by a cutting device and divided into individual device chips, and the divided device chips are widely used in various electronic devices such as mobile phones and personal computers.

  A grinding apparatus that grinds the back surface of a workpiece such as a wafer is a grinding machine in which a chuck table for holding a wafer and a grinding wheel to which a grinding wheel for grinding the wafer held on the chuck table is fixed are rotatably mounted. A unit, and the wafer can be ground to a desired thickness with high accuracy.

  In general, for grinding workpieces such as wafers, the work held on a chuck table (holding table) in a rough grinding unit with a rough grinding wheel and a finish grinding unit with a finish grinding wheel. Rough grinding and finish grinding are performed with the object positioned. A coarse grinding wheel having a coarse grain size is fixed to the coarse grinding wheel, and a finishing grinding wheel having a fine grain size is fixed to the finish grinding wheel.

  Since rough grinding and finish grinding are performed sequentially on the work piece, usually a plurality of chuck tables are rotatably mounted on the turn table so that the turn table can be rotated along the work attachment / detachment area and the work area. It is arranged.

  In the grinding machine, after replacing the grinding wheel or chuck table, so-called self-grinding is performed in which the chuck table is ground with the grinding wheel so that the grinding surface of the grinding wheel and the holding surface of the chuck table are formed in parallel. ing.

  During grinding of the workpiece, the thickness of the workpiece is ground while detecting the thickness of the workpiece from the height position of the upper surface of the chuck table and the height position of the upper surface of the workpiece. (For example, refer to JP 2001-009716 A and JP 2001-001261 A).

JP 2001-009716 A JP 2001-001261 A

  In order to grind a plurality of workpieces respectively held on a plurality of chuck tables to a predetermined thickness, it is necessary to make the holding surface heights of the plurality of chuck tables uniform. Therefore, even if it is desired to perform self-grinding for only one chuck table, it is necessary to perform self-grinding to other chuck tables so that the holding surface heights of the plurality of chuck tables are uniform, and the chuck does not require self-grinding. There was a problem that the chuck table was replaced more frequently by cutting the table.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a grinding apparatus capable of reducing the replacement frequency of the chuck table and a grinding method using the grinding apparatus.

According to the present invention, a turntable that is rotatably disposed along a workpiece attaching / detaching region and a processing region, and is rotatably disposed on the turntable and sequentially moved to the processing region to hold the workpiece. A plurality of chuck tables each having a holding surface, a grinding means including a grinding wheel disposed facing the holding surface of the chuck table positioned in the processing region, and the chuck positioned in the processing region Thickness detection means for detecting the thickness of the workpiece held on the chuck table from the upper surface height position of the table and the upper surface height position of the workpiece held on the chuck table positioned in the machining area When, a grinding method for grinding a workpiece with a grinding apparatus provided with a height position adjusting means for adjusting the height position of each of the chuck table, a plurality of tea in the machining area A chuck table grinding step of positioning the first chuck table of the cuff table and grinding the first chuck table with the grinding means so that the holding surface of the first chuck table and the grinding surface of the grinding wheel are parallel to each other; After the chuck table grinding step, the chuck table is lifted by the height position adjusting means in the first chuck table by the height position of the first chuck table reduced by grinding in the chuck table grinding step. After performing the height position changing step and the chuck table height position changing step, the holding step for holding the workpiece by the first chuck table, and the holding by the first chuck table positioned in the processing region While the thickness of the processed workpiece is detected by the thickness detecting means, the workpiece is removed by the grinding means. Grinding method which comprises a grinding step of grinding, it is provided.

  Since the grinding apparatus of the present invention includes the height position adjusting means for adjusting the height position of the chuck table, when self-grinding is performed only on one chuck table, the height is cut by the self-grinding. Since the position of the chuck table can be raised to the original height by the position adjustment means, it is not necessary to perform self-grinding for other chuck tables, and the chuck table can be replaced more frequently by cutting unnecessary chuck tables. The replacement frequency of the chuck table can be reduced without speeding up.

It is a perspective view of the grinding device concerning an embodiment. It is a partially broken perspective view of the chuck table mounting structure provided with the height position adjusting means. It is a partially broken side view of the grinding apparatus shown in FIG. It is explanatory drawing of a height position adjustment means. It is a partial cross section side view which shows a chuck table grinding step. It is a partial cross section side view which shows a holding | maintenance step. It is a partial cross section side view which shows a grinding step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a grinding apparatus 2 according to an embodiment of the present invention is shown. Reference numeral 4 denotes a base of the grinding apparatus 2, and two columns 6 a and 6 b are vertically provided behind the base 4.

  A pair of guide rails (only one is shown) 8 extending in the vertical direction is fixed to the column 6a. A rough grinding unit 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The rough grinding unit 10 is attached to a moving base 12 whose housing 20 moves up and down along a pair of guide rails 8.

  The rough grinding unit 10 includes a housing 20, a spindle 21 (see FIG. 3) rotatably accommodated in the housing 20, a servo motor 22 that rotationally drives the spindle 21, and a wheel mount fixed to the tip of the spindle 21. 23 and a grinding wheel 24 detachably attached to the wheel mount 23. The grinding wheel 24 is configured by a plurality of grinding wheels 26 fixed in an annular shape on the outer periphery of the lower end portion of the annular base 25.

  The rough grinding unit 10 includes a rough grinding unit moving mechanism 18 including a ball screw 14 and a pulse motor 16 that move the rough grinding unit 10 up and down along a pair of guide rails 8. When the pulse motor 16 is pulse-driven, the ball screw 14 rotates and the moving base 12 is moved in the vertical direction.

  A pair of guide rails (only one is shown) 48 extending in the vertical direction are also fixed to the other column 6b. A finish grinding unit 28 is mounted along the pair of guide rails 48 so as to be movable in the vertical direction.

  The finish grinding unit 28 is attached to a moving base (not shown) whose housing 36 moves up and down along a pair of guide rails 48. The finish grinding unit 28 includes a housing 36, a spindle (not shown) rotatably accommodated in the housing 36, a servo motor 38 that rotationally drives the spindle, and a grinding wheel 42 for finish grinding fixed to the tip of the spindle. A grinding wheel 40 is included.

  The finish grinding unit 28 includes a finish grinding unit moving mechanism 34 including a ball screw 30 and a pulse motor 32 that move the finish grinding unit 28 in the vertical direction along a pair of guide rails 48. When the pulse motor 32 is driven, the ball screw 30 rotates and the finish grinding unit 28 is moved in the vertical direction.

  The grinding device 2 includes a turntable 44 disposed so as to be substantially flush with the upper surface of the base 4 on the front side of the columns 6a and 6b. The turntable 44 is formed in a relatively large-diameter disk shape, and is rotated in a direction indicated by an arrow 45 by a rotation drive mechanism (not shown).

  On the turntable 44, three chuck tables (holding tables) 46 are disposed so as to be rotatable in a horizontal plane while being spaced apart from each other by 120 ° in the circumferential direction. The chuck table 46 has a suction holding portion formed in a disk shape by a porous ceramic material, and sucks and holds the wafer placed on the holding surface of the suction holding portion by operating a vacuum suction means.

  The three chuck tables 46 arranged on the turntable 44 have a wafer carry-in / out area (wafer attach / detach area) A, a rough grinding area B, a finish grinding area C, as the turntable 44 rotates appropriately. And sequentially moved to the wafer carry-in / carry-out area A.

  A front portion of the base 4 includes a wafer cassette 50, a wafer transfer robot 54 having a hand 52, a positioning table 56 having a plurality of positioning pins 58, a wafer carry-in mechanism (loading arm) 60, and a wafer carry-out mechanism (an unloader). Loading arm) 62, a spinner cleaning device 64 that cleans and spin-drys the ground wafer, and a storage cassette 66 that stores the ground wafer that has been cleaned and spin-dried by the spinner cleaning device 64.

  The spinner cleaning device 64 is equipped with a spinner table 68 having a diameter smaller than that of the semiconductor wafer 11 that rotates while sucking and holding the ground semiconductor wafer 11. Reference numeral 70 denotes a cover of the spinner cleaning device 64.

  Adjacent to the chuck table 46 positioned in the rough grinding region B, a first thickness detection unit (first height gauge) 72 is disposed on the base 4, and the chuck table 46 positioned in the finish grinding region C. A second thickness detection unit (second height gauge) 74 is disposed on the base 4 adjacent to the base 4.

  The first thickness detection unit 72 includes a chuck table upper surface height position detection needle 72a and a workpiece upper surface height position detection needle 72b. Similarly, the second thickness detection unit 74 includes a chuck table upper surface height position detection needle 74a and a workpiece upper surface height position detection needle 74b.

  Referring to FIG. 2, a partially broken perspective view of the support structure for the chuck table 46 provided with the height position adjusting means 90 according to the embodiment of the present invention is shown. FIG. 3 is a partially cutaway side view of the grinding apparatus 2 shown in FIG.

  As shown in FIG. 2, the chuck table 46 includes a suction holding portion 49 formed in a disk shape from a porous ceramic material, and a metal frame 47 surrounding the suction holding portion 49. An annular flange 51 is formed integrally with the frame 47. The chuck table 46 is connected to a motor 78 and is driven to rotate by the motor 78. The holding surface which is the upper surface of the suction holding portion 49 is formed flush with the upper surface of the metal frame 47.

  As shown in FIG. 3, the turntable 44 includes a turntable base 44a and a turntable cover 44b, and the chuck table 46 projects upward from an opening 53 formed in the turntable cover 44b.

  Referring to FIG. 2 again, the annular flange 51 is formed with three through holes that are 120 degrees apart from each other in the circumferential direction. Bolts 80 are inserted into the through holes formed in the flange 51, and the front ends of the bolts 80 are engaged with one end portions of the rods 84 inserted into the through holes 83 formed in the turntable base 44. . The rod 84 has a screw hole, and a male screw 89 formed on the output shaft 88 of the pulse motor 86 is screwed into the screw hole.

  A height position adjusting means (movable support portion) 90 is configured by a connection structure of the pulse motor 86, the rod 84, and the bolt 80. Other through-hole portions not visible in FIG. 2 are also supported by similar height position adjusting means (movable support portions) 90. That is, the chuck table 46 of the present embodiment is supported by the three height position adjusting means 90 that are 120 degrees apart from each other in the circumferential direction so that the height position can be adjusted.

  The pulse motor 86 is fixed to the turntable base 44a by a bracket (not shown). When the pulse motor 86 is driven, the male screw 89 is rotated to move the bolt 80 constituting the height position adjusting means 90 in the vertical direction, and the height position of the holding surface of the chuck table 46 is adjusted.

  Referring to FIG. 3, the turntable base 44 a of the turntable 44 is mounted on the motor 92 and is rotated by the motor 92. The suction holding unit 49 of the chuck table 46 is connected to a vacuum suction source via a tube 94, and a suction force is generated in the suction holding unit 49 by the vacuum suction source. The pulse motor 86 constituting each height position adjusting means 90 is connected to the control means 100 and controlled by the control means 100.

  Next, a method for adjusting the holding surface of the chuck table 46 using the height position adjusting means 90 will be described with reference to the schematic diagram of FIG. The chuck table 46 is provided with height position adjusting means 90 at three points (A axis, B axis, C axis) separated from each other by 120 degrees in the circumferential direction. Reference numeral 96 denotes a rotation locus of the grinding wheel 24, and 98 denotes a grinding area by the grinding wheel 24, respectively.

  As shown in FIG. 5, the suction holding portion 49 of the chuck table 46 is formed in a slight mountain shape with the rotation shaft 46a of the chuck table 46 as the apex, and when the diameter of the suction holding portion 49 is 10 cm, the holding surface The difference in height between the central portion and the peripheral portion of 49a is formed to be about 10 to 20 μm.

  Since the holding surface 49a is formed in a mountain shape, the chuck table 46 is disposed such that the central axis 46a is slightly inclined from the vertical direction. Accordingly, when both the chuck table 46 and the grinding wheel 24 rotate counterclockwise in FIG. 4, the grinding region 98 of the grinding wheel 24 is limited to the range from the center of the chuck table 46 to the outer periphery.

  Referring again to FIG. 4, the grinding shape of the workpiece can be adjusted to the middle convex / center concave shape by changing the height position of only the A axis. The grinding shape of the workpiece can be adjusted to a biconvex / biconcave shape by changing the height position of only the C axis. Further, by changing the height position of the three axes A, B, and C by the same amount, the height position of the holding surface of the chuck table 46 can be adjusted without changing the grinding shape of the workpiece.

  Hereinafter, the adjustment of the height position of the holding surface 49a of the chuck table 46 of the grinding apparatus 2 configured as described above will be described. When the grinding apparatus 2 in which the three chuck tables 46 are mounted on the turntable 44 is newly installed in a factory or the like, in order to grind the wafers 11 respectively held by the plurality of chuck tables 46 to a predetermined thickness, The holding surface heights of the plurality of chuck tables 46 need to be made uniform.

  Therefore, self-grinding is performed on each chuck table 46 by grinding each chuck table 46 with the grinding wheel 24 and forming the grinding surface of the grinding wheel 24 and the holding surface of the chuck table 46 in parallel.

  Self-grinding using the grinding wheel 24 will be described with reference to FIG. Note that self-grinding may be performed by attaching a grinding wheel dedicated to self-grinding.

  In self-grinding, the chuck table 46 is rotated in the direction of arrow a while the chuck table upper surface height position detection needle 72a of the first thickness detection unit 72 is in contact with the holding surface 49a of the chuck table 46, and the grinding wheel 24 is ground. The grindstone 26 is brought into contact with the holding surface 49 a of the suction holding portion 49 and the grinding wheel 24 is rotated in the direction of the arrow b, whereby the suction holding portion 49 of the chuck table 46 is ground together with the frame body 47. The grinding surface and the holding surface 49 a of the chuck table 46 are formed in parallel.

  When the grinding apparatus is installed, this self-grinding is performed on the three chuck tables 46 so that the heights of the holding surfaces 49a of the three chuck tables 46 are made uniform. The detection of the height position of the holding surface 49 a is performed by the chuck table upper surface height position detection needle 72 a of the first thickness detection unit 72.

  Therefore, during the grinding of a workpiece such as a wafer, the height positions of the holding surfaces 49a of the three chuck tables 46 are maintained at the same height. When it is necessary to replace one chuck table 46 after grinding the workpiece for a long time, the chuck table is replaced with a new chuck table 46.

  When the chuck table 46 is replaced with a new chuck table as described above, self-grinding is performed on the replaced chuck table so that the grinding surface of the grinding wheel 24 and the holding surface 49a of the chuck table 46 are formed in parallel.

  During the self-grinding, self-grinding is performed while the chuck table upper surface height position detection needle 72a of the first thickness grinding unit 72 is in contact with the holding surface 49a of the chuck table 46.

  As a result, the height cut by self-grinding is determined, so that the holding surface 49a of the chuck table 46 is operated by the height position adjusting means 90 at the same time as the A-axis, B-axis, and C-axis shown in FIG. To raise.

  As a result, the height position of the holding surface 49a of the replaced chuck table 46 is the same as the height position of the holding surfaces 49a of the other two chuck tables 46, so that the workpiece is ground in this state. can do.

  As described above, according to the grinding apparatus 2 of the present embodiment, the height position adjusting means 90 for adjusting the height position of the chuck table 46 is provided. When implemented on the table, the height position of the chuck table 46 that has been cut by self-grinding can be raised.

  Accordingly, it is not necessary to perform self-grinding to the other chuck table 46, and the chuck table replacement frequency can be reduced without cutting the unnecessary chuck table without increasing the chuck table replacement frequency.

  The self-grinding of the replaced chuck table 46 is performed, and the chuck table 46 is raised by the height position adjusting means 90 by the height position of the chuck table 46 reduced by grinding by self-grinding, and the holding surface 49a is moved to another position. Then, the holding step of sucking and holding the wafer 11 by the suction holding portion 49 of the chuck table 46 is performed as shown in FIG. The front surface of the wafer 11 is protected by a surface protection tape 13, and the back surface of the wafer 11 is exposed.

  After carrying out the holding step, the turntable 44 is rotated 120 degrees in the direction of the arrow 45 to position the chuck table 46 holding the wafer 11 in the rough grinding region B. Then, as shown in FIG. 7, while rotating the chuck table 46 holding the wafer 11 in the direction of arrow a at 300 rpm, for example, the grinding wheel 24 is rotated in the same direction as the chuck table 46, that is, in the direction of arrow b at 6000 rpm, for example. At the same time, the rough grinding unit moving mechanism 18 is operated to bring the grinding wheel 26 for rough grinding into contact with the back surface of the wafer 11.

  Then, the grinding wheel 24 is moved downward at a predetermined grinding feed speed, and the wafer 11 is roughly ground while pressing the wafer 11 with the grinding wheel 26. In this rough grinding, the chuck table upper surface height position detection needle 72 a of the first thickness detection unit 72 is brought into contact with the holding surface 49 a of the chuck table 46, and the workpiece upper surface height position detection needle 72 b is placed on the rear surface of the wafer 11. Grinding is performed while abutting, and the wafer 11 is roughly ground to a desired thickness.

  After the rough grinding is completed, the turntable 44 is further rotated 120 degrees in the direction of the arrow 45 to position the rough ground wafer 11 in the finish grinding region C. Then, finish grinding of the wafer 11 by the finish grinding unit 28 is performed.

  During this finish grinding, the chuck table upper surface height position detection needle 74 a of the second thickness detection unit 74 is brought into contact with the holding surface 49 a of the chuck table 46, and the workpiece upper surface height position detection needle 74 b is moved to the wafer 11. Finish grinding is performed while contacting the back surface to finish the wafer 11 to a desired thickness.

2 Grinding device 10 Rough grinding unit 24 Rough grinding wheel 28 Finish grinding unit 40 Finish grinding wheel 44 Turntable 46 Chuck table 49 Suction holding portion 49a Holding surface 72 First thickness grinding unit 74 Second thickness grinding unit 80 Bolt 84 Rod 86 Pulse Motor 90 Height position adjusting means (movable support part)

Claims (1)

A workpiece attachment / detachment region, a turntable rotatably disposed along the processing region, and a holding surface that is rotatably disposed on the turntable and is sequentially moved to the processing region to hold the workpiece. Grinding means including a plurality of chuck tables, a grinding wheel disposed facing the holding surface of the chuck table positioned in the processing region, and an upper surface height of the chuck table positioned in the processing region Thickness detecting means for detecting the thickness of the workpiece held on the chuck table from the position and the upper surface height position of the workpiece held on the chuck table positioned in the machining area; and each chuck A height position adjusting means for adjusting the height position of the table, and a grinding method for grinding a workpiece with a grinding apparatus comprising:
The first chuck table of the plurality of chuck tables is positioned in the processing region, and the first chuck table is ground by the grinding means so that the holding surface of the first chuck table and the grinding surface of the grinding wheel are parallel to each other. The chuck table grinding step,
After performing the chuck table grinding step, the height of the chuck table is raised by the height position adjusting means in the first chuck table by the height position of the first chuck table reduced by grinding in the chuck table grinding step. Position change step,
A holding step for holding the workpiece on the first chuck table after performing the chuck table height position changing step;
A grinding step of grinding the workpiece by the grinding means while detecting the thickness of the workpiece held by the first chuck table positioned in the machining area by the thickness detecting means;
A grinding method comprising:

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