JP4408311B2 - Method for correcting chuck table in grinding apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to modified how the chuck table in the grinding apparatus having a plurality of chuck table for holding a workpiece.
[0002]
[Prior art]
As is well known to those skilled in the art, in the semiconductor device manufacturing process, the surface of the semiconductor wafer is ground in order to form a substantially disc-shaped semiconductor wafer to a predetermined thickness. Such a surface grinding apparatus for grinding the surface of a semiconductor wafer is provided with a plurality of chuck tables for holding a semiconductor wafer as a workpiece, the plurality of chuck tables, and each chuck table at a predetermined grinding position. And a grinding unit provided with a grinding wheel for grinding the semiconductor wafer disposed at the grinding position and held on the chuck table. In such a grinding apparatus having a plurality of chuck tables, the heights of the plurality of chuck tables are made uniform in order to grind the semiconductor wafer held on the plurality of chuck tables to a predetermined thickness. Need to be prepared.
[0003]
In order to make the height of each chuck table uniform, the surface of each chuck table is ground and corrected by a grinding wheel of a grinding unit provided in the grinding apparatus itself. The chuck table is ground by, for example, controlling all the feed means for adjusting the cutting depth of the grinding wheel and moving all the chucks mounted on the turntable by moving the grinding unit including the grinding wheel to a predetermined feed position. It is implemented for the table. For example, when a pulse motor is used as a drive source, the feed means is controlled by controlling the number of drive pulses, and when a linear scale is provided, feedback control is performed.
[0004]
[Problems to be solved by the invention]
Thus, in the above-mentioned correction of the chuck table, even if the control of the number of driving pulses and the feedback control are performed with high accuracy, the grinding wheel wears out. For example, all chucks within an error range of 5 μm or less. In order to make the height of the table uniform, it is necessary to make fine adjustments while actually measuring the grinding results. This adjustment work requires a great deal of time and labor, and requires a skilled technique. In addition, the correction of the chuck table is performed a relatively large number of times, such as when the grinding machine is manufactured, when it is installed in the customer's factory, and during maintenance. There is a problem that the rate decreases and the productivity deteriorates.
[0005]
The present invention has been made in view of the above circumstances, the principal technical problem, provides a modified how the chuck table in the grinding apparatus capable of uniformly corrected in a short time the height of the plurality of chuck table There is to do.
[0006]
[Means for Solving the Problems]
In order to solve the above main technical problem, according to the present invention, a plurality of chuck tables for holding a workpiece, and a turntable in which the plurality of chuck tables are arranged and each chuck table is positioned at a predetermined grinding position. And a grinding unit provided with a grinding wheel for grinding a work piece disposed at the grinding position and held on the chuck table, the height of each chuck table in a grinding apparatus comprising: A chuck table correction method,
A height measuring step for measuring the height of each chuck table;
Of the measurement values obtained by the height measurement step, a reference value setting step with the lowest value as a reference value;
Grinding a surface of a chuck table other than the chuck table for which the reference value has been set by the grinding unit until the reference value is reached while measuring the height thereof.
A method of correcting a chuck table in a grinding apparatus is provided.
[0007]
The chuck table is composed of a suction holding chuck, and its suction area is formed by a porous ceramic disk. It is desirable that the cooling liquid be ejected from the suction area in the grinding step.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the modifications how the chuck table in the constructed grinding apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0010]
Shows a perspective view of a surface grinding apparatus for carrying out the modifications how the chuck table according to the invention in FIG.
The grinding device includes a device housing 2 having a substantially rectangular parallelepiped shape. A stationary support plate 4 is erected on the upper right end of the device housing 2 in FIG. Two pairs of guide rails 6 and 6 and guide rails 8 and 8 extending in the vertical direction are provided on the inner surface of the stationary support plate 4. A rough grinding unit 10 is mounted on one of the guide rails 6 and 6 so as to be movable in the vertical direction, and a finish grinding unit 12 is mounted on the other guide rails 8 and 8 so as to be movable in the vertical direction.
[0011]
The rough grinding unit 10 includes a unit housing 101, a grinding wheel 102 that is rotatably attached to the lower end of the unit housing 101 and is rotated in the direction indicated by an arrow 10a by a rotation driving mechanism 100, and a support that is attached to the unit housing 101. A block 103 and a moving base 105 attached to the support block 103 by a plurality of mounting bolts 104 are provided. The movable base 105 is provided with guided rails 106 and 106, and by fitting the guided rails 106 and 106 to the guide rails 6 and 6 provided on the stationary support plate 4, The rough grinding unit 10 is supported so as to be movable in the vertical direction. The rough grinding unit 10 in the illustrated form includes a feed mechanism 11 that moves the moving base 105 along the guide rails 6 and 6 to adjust the cutting depth of the grinding wheel 102. As shown in FIG. 2, the feed mechanism 11 is provided with a male screw rod 111 disposed in a vertical direction parallel to the outer surface of the stationary support plate 4, and a male screw rod 111 mounted on the rear side of the stationary support plate 4. A pulse motor 112, a bearing block 113 that is mounted on the upper portion of the outer surface of the stationary support plate 4 and rotatably supports the lower end of the male screw rod 111, and is mounted on the moving base 105 and screwed with the male screw rod 111. The rough threading unit 10 is moved up and down by driving the male thread rod 111 forward and backward by a pulse motor 112. The stationary support plate 4 has a long hole that allows the female screw block 114 to move. In the illustrated embodiment, a grinding wheel movement amount detection means 13 for detecting the movement amount of the rough grinding unit 10, that is, the grinding wheel 102 is provided. The grinding wheel movement amount detecting means 13 is a detection unit for detecting a detected line of the linear scale 131 attached to the female screw block 114 and a linear scale 131 which is arranged in parallel to the male screw rod 111 and fixed to the stationary support plate 4. And a container 132. The detector 132 may be a well-known photoelectric detector, and generates a pulse signal in response to detection of the detected lines of the linear scale 131 (for example, formed at intervals of 1 μm). To the control means.
[0012]
Returning to FIG. 1, the description of the finish grinding unit 12 is the same as that of the rough grinding unit 10. The finish grinding unit 12 is rotatably mounted at the lower end of the unit housing 121 and the unit housing 121 by the rotary drive mechanism 120. A grinding wheel 122 rotated in the direction indicated by, a support block 123 attached to the unit housing 121, and a moving base 125 attached to the support block 123 by a plurality of mounting bolts 124. Guided rails 126, 126 are provided on the moving base 125, and the guided rails 126, 126 are movably fitted to the guide rails 8, 8 provided on the stationary support plate 4. The finish grinding unit 12 is supported so as to be movable in the vertical direction. The finish grinding unit 12 in the form shown in the figure includes a feed mechanism 14 that moves the moving base 125 along the guide rails 8 and 8 and adjusts the cutting depth of the grinding wheel 122. The feed mechanism 14 has substantially the same configuration as the feed means 11. In the illustrated embodiment, the grinding wheel movement amount detecting means for detecting the movement amount of the finish grinding unit 12, that is, the grinding wheel 112 is provided. This grinding wheel movement amount detection means has substantially the same configuration as the grinding wheel movement amount detection means 13 for detecting the movement amount of the rough grinding unit 10.
[0013]
The grinding device in the illustrated embodiment includes a turntable 20 disposed so as to be substantially flush with the upper surface of the device housing 2 on the front side of the stationary support plate 4. The turntable 20 is formed in a relatively large-diameter disk shape, and is appropriately rotated in the direction indicated by the arrow 20a by a rotation drive mechanism (not shown). In the illustrated embodiment, four chuck tables 22 are arranged on the turntable 20 so as to be rotatable in a horizontal plane with a phase angle of 90 degrees. The chuck table 22 uses, for example, a suction holding chuck that holds the workpiece on the upper surface of the suction region 221 by suction means as described in JP-A-61-182838. It is rotated in the direction indicated by the arrow 22a by the rotation drive mechanism. The suction area 221 of the chuck table 22 is formed by a porous ceramic board. In this way, the four chuck tables 22 arranged on the turntable 20 have a workpiece carry-in area A, a rough grinding area B, a finish grinding area C, and a work piece by appropriately rotating the turntable 20. It is sequentially moved to the object carry-out area D.
[0014]
The illustrated grinding apparatus includes a first cassette 24 that is disposed on the workpiece carry-in area A side and stocks a semiconductor wafer that is a workpiece before grinding, and is disposed on the workpiece carry-out area D side for grinding. A second cassette 26 for stocking a semiconductor wafer, which is a workpiece to be processed, a workpiece mounting portion 28 provided between the first cassette 24 and the workpiece carry-in area A, and a second The cleaning means 30 disposed between the cassette 24 and the workpiece unloading area D and the semiconductor wafer, which is the workpiece stored in the first cassette 24, are carried out to the workpiece mounting portion 28. At the same time, the workpiece conveying means 32 for conveying the semiconductor wafer cleaned by the cleaning means 30 to the second cassette 26 and the semiconductor wafer placed on the workpiece placing portion 28 in the workpiece carry-in area A. Carry on the positioned chuck table 22 A workpiece carrying-in means 34 for carrying out and a workpiece carrying-out means 36 for carrying the semiconductor wafer after grinding mounted on the chuck table 22 positioned in the workpiece carrying-out area D to the cleaning means 30. It has.
[0015]
Next, the processing operation of the above-described grinding apparatus will be briefly described.
The pre-grinding semiconductor wafer accommodated in the first cassette 24 is transported by the up-and-down motion and the back-and-forth motion of the workpiece transport means 32 and is placed on the workpiece placing portion 28. The semiconductor wafer placed on the workpiece placing portion 28 is placed on the chuck table 22 positioned in the workpiece carrying-in area A by the turning operation of the workpiece carrying-in means 34. The semiconductor wafer placed on the chuck table 22 is sucked and held on the chuck table 22 by an air intake means (not shown). Then, the turntable 20 is rotated 90 degrees in the direction indicated by the arrow 20a by a rotation drive mechanism (not shown), and the chuck table 22 on which the semiconductor wafer is placed is positioned in the rough grinding region B.
[0016]
When the chuck table 22 on which the semiconductor wafer is placed is positioned in the rough grinding region B, the chuck table 22 is rotated in the direction indicated by the arrow 22a by a rotation drive mechanism (not shown), while the grinding wheel 102 of the rough grinding unit 10 is indicated by the arrow 10a. The semiconductor wafer on the chuck table 22 is subjected to rough grinding by being lowered by a predetermined amount by the feed mechanism 11 while being rotated in the direction. During this time, the semiconductor wafer before grinding is placed on the next chuck table 22 positioned in the workpiece carry-in area A as described above. Next, the turntable 20 is rotated 90 degrees in the direction indicated by the arrow 20a, and the chuck table 22 on which the semiconductor wafer subjected to rough grinding is placed is positioned in the finish grinding region C. At this time, the next chuck table 22 on which the semiconductor wafer is placed in the workpiece carry-in area A is positioned in the rough grinding area B, and the next next chuck table 22 is positioned in the workpiece carry-in area A. .
[0017]
In this way, the semiconductor wafer placed on the chuck table 22 positioned in the finish grinding region C and the rough grinding region B and subjected to the rough grinding and the semiconductor wafer before the rough grinding are the finish grinding unit 12 and The rough grinding unit 10 performs finish grinding and rough grinding. Next, the turntable 20 is rotated 90 degrees in the direction indicated by the arrow 20a, and the chuck table 22 on which the semiconductor wafer subjected to finish grinding is placed is positioned in the workpiece unloading area D. The chuck table 22 on which the semiconductor wafer subjected to rough grinding in the rough grinding region B is placed is in the finish grinding region C, and the chuck table on which the semiconductor wafer before grinding is placed in the workpiece carry-in region A. 22 is moved to the rough grinding zone B, respectively.
[0018]
The chuck table 22 positioned in the workpiece unloading area D releases the suction holding of the semiconductor wafer subjected to the finish grinding here. Then, the semiconductor wafer subjected to finish grinding on the chuck table 22 positioned in the workpiece unloading area D is conveyed to the cleaning unit 30 by the workpiece unloading unit 36 and cleaned there. The semiconductor wafer 11 cleaned by the cleaning unit 30 is stored in a predetermined position of the second cassette 24 by the workpiece transfer unit 32.
[0019]
The grinding apparatus configured as described above includes a height gauge 40 for detecting the height of the chuck table 22 as shown in FIG. The height gauge 40 detects the height of the chuck table 22 positioned in the rough grinding area B in the illustrated embodiment, and sends the detection signal to the control means 50. The control means 50 includes a central processing unit (CPU) that performs arithmetic processing according to a control program, a read-only memory (ROM) that stores a control program, and a readable / writable random access memory (RAM) that stores arithmetic results and the like. . The control means 50 configured as described above receives detection signals from the height gauge 40, the detector 132 of the grinding wheel movement amount detection means 13, the chuck table correction switch 51, and the like, and sends the control signals to the pulse motor 112 and the above. A control signal is output to the rotation drive mechanism of the turntable 20 and the chuck table 22, and a detected value from the height gauge 40 is output to the display means 52. The control means 50 also outputs control signals to the cleaning means 30, the workpiece conveying means 32, the workpiece carrying-in means 34, and the workpiece carrying-out means 36.
[0020]
Next, a chuck table correcting method for uniformly aligning the heights of the four chuck tables 22 arranged on the turntable 20 in the above-described grinding apparatus will be described.
First, when the chuck table correction switch 51 is turned on, the four chuck tables 22 arranged on the turntable 20 are sequentially positioned in the rough grinding area B and their heights are measured by the height gauge 40. The measurement result is sent to the control unit 50, temporarily stored in the RAM of the control unit 50, and displayed on the display unit 52.
Next, the control unit 50 sets the lowest value among the measured values of the four chuck tables 22 as a reference value and displays it on the display unit 52. The operator may set the lowest value among the measured values of the four chuck tables 22 displayed on the display means 52 as the reference value.
When the reference value is set in this manner, the chuck table 20 other than the chuck table (the chuck table having the lowest height) for which the reference value is set is sequentially positioned in the rough grinding area B, and the rough grinding unit 10 is The surface of the chuck table is ground until it reaches the reference value while operating and measuring the height of the chuck table with the height gauge 40. At this time, clogging of the porous ceramic disk can be prevented by using the suction means of the chuck table 22 to eject the cooling liquid from the suction region 221 formed by the porous ceramic disk and grinding the surface of the chuck table. Is desirable.
In addition, since the surface of the chuck table may not appear at the time of manufacturing the grinding apparatus, it is necessary to grind the surface of all the chuck tables and perform flattening before performing the correction work according to the present invention. .
As described above, the chuck tables other than the lowest height chuck table set as the reference value are ground until they reach the reference value, so that the heights of the four chuck tables 22 can be aligned with the reference value. it can. That is, chuck tables other than the chuck table having the lowest reference value are ground until the reference value is reached while measuring the height of the chuck table with the height gauge 40, so that the grinding wheel of the grinding unit is worn out. However, each chuck table can be uniformly corrected, and the error range can be within 5 μm. Further, when the correction time of the chuck table is compared, in the case of a grinding apparatus having four chuck tables, the conventional correction method takes about 16 hours, whereas the correction method according to the present invention requires 2 hours. It became about.
[0021]
The correction operation can be controlled by the control means 50.
That is, when the chuck table correction switch 51 is turned on, the control means 50 sets the lowest value as a reference value based on the measurement signal from the height gauge 40, and sets a chuck table other than the chuck table set as the reference value. The turntable 20 is controlled to move to the rough grinding area B. Then, the control means 50 operates the rough grinding unit 10 to grind the surface of the chuck table positioned in the rough grinding region B, and when the measurement signal from the height gauge 40 reaches a reference value, the rough grinding unit 10 operates. To stop. By controlling in this way, the chuck table can be automatically corrected.
[0022]
As mentioned above, although the example which applied this invention to the illustrated grinding apparatus was shown, this invention is not limited only to the illustrated grinding apparatus, For example, the grinding apparatus provided with three chuck tables, and the grinding unit are 1 The present invention can be widely applied to a single grinding apparatus.
[0023]
【The invention's effect】
Modify how the chuck table in the grinding apparatus according to the present invention has been constituted as described above, the following beneficial operational effects are obtained.
[0024]
That is, according to the present invention, measurement is performed using the heights of a plurality of chuck tables arranged on the turntable, and the surface of the other chuck table is set to the height of the chuck table having the lowest value as a reference value. Grinding is performed by the grinding unit until the above reference value is reached while measuring the thickness, so that even if the grinding wheel wears out, each chuck table can be corrected uniformly and compared with the conventional chuck table correction method. Thus, the correction time can be greatly shortened. Therefore, the operating rate of the grinding apparatus is remarkably improved, and the productivity can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a surface grinding apparatus to which the present invention is applied.
FIG. 2 is a side view of the main part of the surface grinding apparatus shown in FIG.
FIG. 3 is a schematic configuration diagram of a control circuit provided in the surface grinding apparatus shown in FIG. 1;
[Explanation of symbols]
2: Device housing 4: Stationary support plate 4
6: guide rail 8: guide rail 10: rough grinding unit 101: unit housing 102: grinding wheel 103: support block 105: moving base 106: guided rail 11: feed mechanism 111: male screw rod 112: pulse motor 113: bearing Block 13: Grinding wheel movement detection means 131: Linear scale 132: Detector 12: Finish grinding unit 121: Unit housing 122: Grinding wheel 123: Support block 125: Moving base 126: Guided rail 14: Feed mechanism 20: Turntable 22: Chuck table 24: First cassette 26: Second cassette 28: Workpiece placement unit 30: Cleaning means 32: Workpiece conveying means 34: Workpiece carrying means 36: Workpiece carrying out Means 40: Height gauge 50: Control means

Claims (2)

A plurality of chuck tables for holding a workpiece, a turn table for disposing the plurality of chuck tables and positioning each chuck table at a predetermined grinding position, and being disposed at the grinding position and held by the chuck table A chuck table correction method for aligning the height of each chuck table in a grinding apparatus comprising a grinding unit having a grinding wheel for grinding a workpiece.
A height measuring step for measuring the height of each chuck table;
Of the measurement values obtained by the height measurement step, a reference value setting step with the lowest value as a reference value;
Grinding a surface of a chuck table other than the chuck table for which the reference value has been set by the grinding unit until the reference value is reached while measuring the height thereof.
A method for correcting a chuck table in a grinding apparatus.   2. The correction of the chuck table in the grinding apparatus according to claim 1, wherein the chuck table is constituted by an adsorption holding chuck, and the suction area is formed by a porous ceramic disk, and in the grinding step, cooling liquid is ejected from the suction area. Method.

Images