JPH11198008A - Surface grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To register an accurate basic position of a grinding wheel by registering the basic position automatically. SOLUTION: According to the method of registering a basic position of a straight cup grinding wheel 64, the straight cup grinding wheel 64 is to be moved toward a chuck table 52 by controlling a grinding wheel feeding device with a CPU. When the straight cup grinding wheel 64 comes in contact with the chuck table 52, the chuck table 52 is displaced to the axial direction by being pushed by the straight cup grinding wheel 64, therefore electric signals are outputted from a piezoelectric element 114. The position of the straight cup grinding wheel 64 when the detection signals are outputted is registered in a RAM of the CPU as a basic position. The movement of the cup straight cup grinding wheel 64 is stopped by controlling the grinding wheel feeding device simultaneously with the output of the electric signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface grinding device, and more particularly to a surface grinding device for grinding a back surface of a semiconductor wafer in a semiconductor wafer (work) manufacturing process.

[0002]

2. Description of the Related Art A surface grinding apparatus for grinding a back surface of a semiconductor wafer is provided with a chuck table and a grinding wheel. The chuck table suction-holds the surface of the wafer and presses the grinding wheel against the back surface of the wafer. At the same time, the back surface of the wafer is ground by rotating the chuck table and the grinding wheel.

In such a surface grinding apparatus, a reference (zero point) position of a grinding wheel is registered in advance before grinding, and a feed amount of the grinding wheel is set based on the reference position.
The amount of grinding is controlled. In the conventional reference position registration method, a worker manually fine-feeds a grinding wheel toward a chuck table, and registers a position where the grinding wheel is visually confirmed to be in contact with the chuck table as a reference position. .

[0004]

However, the conventional surface grinding apparatus has a drawback that the registration of the reference position is performed manually, which is troublesome. In addition, in the manual registration method, there is a case where the position where the grinding wheel contacts the chuck table cannot be accurately detected, and thus there is a disadvantage that an accurate reference position cannot be registered.

The present invention has been made in view of such circumstances, and provides a surface grinding apparatus capable of registering an accurate reference position by automatically registering a reference position of a grinding wheel. Aim.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a grinding apparatus main body, a chuck table provided on the grinding apparatus main body and holding a work, and pressed against the work held on the chuck table. Grinding wheel for grinding the workpiece, grinding wheel feeding means for moving the grinding wheel forward and backward with respect to the chuck table, position detecting means for detecting the moving position of the grinding wheel, and axial displacement of the chuck table provided on the chuck table By controlling the displacement detecting means for detecting the position of the grinding wheel and the grinding wheel feeding means to move the grinding wheel toward the chuck table, the grinding wheel is brought into contact with the chuck table, and the grinding is performed when the detection signal is output from the displacement detecting means. The position of the grindstone is registered as a reference position, and when a detection signal is output from the displacement detecting means, the grindstone feeding means is controlled. To is characterized in that it consists of a control means for stopping the movement of the grinding wheel.

According to the reference position registration method by the surface grinding device of the first aspect, the control means controls the grinding wheel feeding means to move the grinding wheel toward the chuck table, and the grinding wheel contacts the chuck table. Then, since the chuck table is displaced in the axial direction, a detection signal is output from the displacement detection means, and the position of the grinding wheel at the time when the detection signal is output is registered as a reference position. Thus, according to the present invention, the registration of the reference position of the grinding wheel can be automatically performed, so that the accurate reference position can be registered.
Further, according to the present invention, since the movement of the grinding wheel is stopped at the same time that the detection signal is output from the displacement detecting unit, it is possible to prevent the chuck table, the grinding wheel, and the grinding wheel feeding unit from being damaged.

According to the second aspect of the present invention, since a piezoelectric element is used as the displacement detecting means, even a small axial displacement of the chuck table can be detected. Therefore, an accurate reference position can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the surface grinding apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a surface grinding apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view. As shown in FIG. 1, a cassette storage stage 1 is provided on a main body 12 of a surface grinding apparatus 10.
4, alignment stage 16, rough grinding stage 18,
A finish grinding stage 20 and a cleaning stage 22 are provided.

Two cassettes 24, 24 are detachably set on the cassette storage stage 14, and a large number of wafers 26 shown by dotted lines in FIG. ing. The wafers 26 are held one by one by a transfer robot 28 installed between the cassettes 24 and are sequentially transferred to the alignment stage 16 which is the next step.

The robot 28 is a general-purpose industrial robot, and is composed of a horseshoe-shaped arm 30 for holding the wafer 26 by suction, and three links 32, 34, 36 and the like. At the tip of the arm 30, suction pads 31, 31 for sucking the wafer 26 are provided. The base end of the arm 30 is rotatably supported by a link 32 about an axis, and can be rotated about the axis by a driving force from a motor (not shown). Link 3
2 is rotatably connected to the link 34 via a shaft 38, and can rotate around the shaft 38 by a driving force from a motor (not shown). The link 34 is rotatably connected to the link 36 via a shaft 40, and can rotate around the shaft 40 by a driving force from a motor (not shown). Further, the link 36 is connected to the motor 44 via the shaft 42.
Of the motor 44
Can be rotated about the shaft 42. Therefore, according to the robot 28, the operation of the arm 30 and the three links 32, 34, 36 is controlled by the respective motors, so that the wafer 26 stored in the cassette 24 is taken out and transferred to the alignment stage 16. can do. The cassette 2
4 and 24 are mounted on the elevator devices 46 and 46, and the elevator devices 46 and 46 are driven to drive the cassettes 24 and 46.
By adjusting the height position of the robot 24, the robot 28 can take out the wafers 26 stored on a predetermined shelf of the cassette 24 without moving the robot 28 up and down. It should be noted that the robot 28 may be provided with an elevating mechanism so that the elevator device is not required.

The alignment stage 16 is a stage for positioning the wafer 26 transferred from the cassette 24 at a predetermined position, and mainly includes an arm 48, a position sensor (not shown), a moving mechanism (not shown), and It is composed of a CPU (not shown) for overall control. The arm 48 is provided with suction pads 49, 49 for sucking the wafer 26 at the tip thereof.
At 9, the wafer 26 transferred from the cassette 24 is held by suction. Wafer 26 held by arm 48
The position is detected by the position sensor, and the amount of deviation from a predetermined position (the amount of deviation of the center of the wafer 26 from the suction position of the transfer arm 50) is calculated by the CPU.
The CPU controls the moving mechanism based on the displacement amount, so that the center of the wafer 26 is positioned so that the wafer 26 is located at a position matching the suction position of the transfer arm 50 (the position of the suction pad 51 in FIG. 2). Move 50. Thus, the alignment of the wafer 26 ends.

After the aligned wafer 26 is sucked and held on the suction pad 51 of the arm 50 described above,
It is conveyed toward the chuck table 52 of the coarse grinding stage 18. That is, the base end of the arm 50 is
4 is connected to an output shaft (not shown) of a motor 56.
From the alignment stage 16 to the coarse grinding stage 18. The motor 56 moves the arm 50 within a range between a position where the suction pad 51 of the arm 50 matches the center of the wafer 26 aligned by the alignment stage 16 and a position where the suction pad 51 matches the center of the chuck table 52. It is controlled by a CPU (not shown) so as to reciprocate.

On the other hand, a plurality of air nozzles 58, 5 are provided between the alignment stage 16 and the coarse grinding stage 18.
8 are provided. These air nozzles 58, 58
Are attached to the upper surface (suction surface) of the chuck table 52, and are connected to an air pump (not shown) built in the main body 12. The air pump is controlled so as to be driven immediately before the wafer 26 is attracted to the chuck table 52, whereby dust adhering to the suction surface (surface) of the wafer 26 or the upper surface of the chuck table 52 is removed by the air nozzle 58, 58 ... can be blown off by compressed air or high-pressure air. Further, it may be blown off with water instead of air. When blowing off with compressed air, air or water is simultaneously blown up from the chuck table.

The thickness of the wafer 26 sucked and held on the chuck table 52 is measured by two thickness measuring gauges 60 and 62. That is, the thickness measurement gauge 6
0 contacts the upper surface (back surface) of the wafer 26 and the thickness measurement gauge 62 contacts the upper surface of the chuck table 52. The CPU (not shown) connected to the gauges 60 and 62 outputs data (height data from a predetermined reference position) output from the gauges 60 and 62.
The thickness of the wafer 26 is calculated by calculating the difference.

The wafer 26 whose thickness has been calculated is roughly ground by the cup-type grindstone 64 of the rough grinding stage 18. The cup-shaped grindstone 64 is connected to an output shaft (not shown) of a motor 66 as shown in FIG.
Is attached to a grindstone feeder (grindstone feed means) 70 via a support casing 68 of the above. The grindstone feeder 70 moves the cup-shaped grindstone 64 up and down together with the motor 66.
4 is pressed against the back surface of the wafer 26. Thereby, the back surface grinding is performed. The amount of downward movement of the cup-shaped grindstone 64, that is, the amount of grinding by the cup-shaped grindstone 64, is controlled based on the reference (zero point) position of the cup-shaped grindstone 64 registered in advance and the thickness of the wafer 26. The reference position registration method will be described later.

The wafer 26 coarsely ground by the coarse grinding stage 18 is sucked by the suction pad 73 of the arm 72 shown in FIG. Then, the wafer 26 is transferred to the chuck table 74 of the finish grinding stage 20 by the swing operation of the arm 72. That is, the base end of the arm 72 is connected to an output shaft (not shown) of a motor 78 via a shaft 76, and the forward rotation of the motor 78 moves the wafer 26 from the rough grinding stage 18 to the finish grinding stage 20. Can be transported. The motor 78 is
The arm 72 is reciprocally oscillated within a range between a position where the tip center 72A of the arm 72 matches the center of the wafer 26 ground by the coarse grinding stage 18 and a position where the tip center 72A matches the center of the chuck table 74. Is controlled by a CPU (not shown). Also, arm 7
The second motor 78 and the motor 56 of the arm 50 described above are connected to the wafer 26 held by the arms 78 and 50 of each other.
However, the drive is controlled at the shortest timing that does not cause interference during transport. Thereby, the wafer 26 is efficiently transferred from the alignment stage 16 to the coarse grinding stage 18 and from the coarse grinding stage 18 to the finish grinding stage 20.

On the other hand, between the rough grinding stage 18 and the finish grinding stage 20, a plurality of air nozzles 80, 80 are provided.
... are provided. These air nozzles 80, 80 ...
Is attached to the upper surface (suction surface) of the chuck table 74 and is connected to an air pump (not shown) built in the main body 12. Air pump for wafer 2
6 is controlled to be driven immediately before the chuck 6 is attracted to the chuck table 74. Thus, dust and the like adhering to the suction surface (front surface) of the wafer 26 and the upper surface of the chuck table 74 can be blown off by the compressed air from the air nozzles 80.

The thickness of the wafer 26 held by suction on the chuck table 74 is measured by two thickness measuring gauges 82 and 84. That is, the thickness measurement gauge 8
2 is brought into contact with the upper surface (back surface) of the wafer 26, and the thickness measurement gauge 84 is brought into contact with the upper surface of the chuck table 74. The CPU (not shown) connected to these gauges 82 and 84 outputs data (height data from a predetermined reference position) output from each gauge 82 and 84.
The thickness of the wafer 26 is calculated by calculating the difference.

The wafer 26 whose thickness has been calculated is finish-ground by the cup-shaped grindstone 86 of the finish grinding stage 20. As shown in FIG.
It is connected to an output shaft (not shown) of the motor 88, and is attached to a grindstone feeder (grindstone feed means) 92 via a support casing 90 of the motor 88. The grindstone feeding device 92 moves the cup-shaped grindstone 86 up and down together with the motor 88, and the downward movement pushes the cup-shaped grindstone 86 against the back surface of the wafer 26. Thereby, the back surface grinding is performed. The amount of downward movement of the cup-shaped grindstone 86, that is, the amount of grinding by the cup-shaped grindstone 86, is controlled based on the reference (zero point) position of the cup-shaped grindstone 86 registered in advance and the thickness of the wafer 26. The reference position registration method will be described later.

The wafer 26 finish-ground by the finish grinding stage 20 is separated from the wafer 26 by a cup-shaped grindstone 86.
Is retracted and then sucked by the suction pad 95 of the arm 94 shown in FIG. Then, the wafer 26 is moved by the swing operation of the arm 94 so that the sink 96 of the cleaning stage 22 is moved.
And is washed by the washing water stored in the sink 96.

The base end of the arm 94 is connected to an output shaft (not shown) of the motor 100 via a shaft 98. The wafer 26 is driven by the forward rotation of the motor 100.
From the finish grinding stage 20 to the cleaning stage 22. The motor 100 is provided with an arm 7 at the center of the wafer 26 ground by the finish grinding stage 20.
A CPU (not shown) controls the arm 96 to reciprocate in a range between a position where the second suction pad 95 matches and a position where the suction pad 95 matches the center of the sink 96. Also, the motor 100 of the arm 94
The drive of the motor 78 of the arm 72 described above is controlled at the shortest timing at which the wafers 26 held by the arms 94 and 72 do not interfere during transfer. Thus, the wafer 26 is efficiently transferred from the rough grinding stage 18 to the finish grinding stage 20 and from the finish grinding stage 20 to the cleaning stage 22.

The wafer 2 cleaned in the cleaning stage 22
6 is sucked and held by the robot 28. Then, after the suction by the arm 94 is released, the robot 28 conveys the wafer from the cleaning stage 22 to the cassette storage stage 14 and stores it on a predetermined shelf of a predetermined cassette 24. The above is the flow of the wafer processing step by the surface grinding apparatus 10 of the present embodiment.

Next, a method of registering the reference positions of the cup-shaped grindstones 64 and 86 by the surface grinding apparatus 10 will be described. Since the reference position registration method of the cup-type grindstones 64 and 86 is the same, only the reference position registration method of the cup-type grindstone 64 will be described here, and the description of the reference position registration method of the cup-type grindstone 86 will be omitted. First, a configuration required to register the reference position will be described with reference to FIG. As shown in the figure, a rotating shaft 102 of the chuck table 52 is provided on the lower surface of the chuck table 52, and the rotating shaft 102 has an output shaft 10 of a motor 104.
6 are connected. Therefore, the chuck table 5
2 is rotated in the direction of the arrow in the figure by the driving force of the motor 104. The rotating shaft 102 of the chuck table 52
Is inserted through a hollow portion 109 of a housing 108 installed on the main body 12, and the bearing 1 is inserted into the hollow portion 109.
It is rotatably supported via 10, 110. The chuck table 52 is rotatably supported by the housing 108 via a bearing 112.

Incidentally, the housing 108 is mounted on the main body 12 via a plurality of piezoelectric elements 114,114. The piezoelectric element 114 is mounted such that an electromotive force is generated when the piezoelectric element 114 is distorted by an axial force of the chuck table 52 indicated by an arrow A in the figure. These piezoelectric elements 114 are connected to a CPU 116 shown in FIG. 4, and the CPU 116 registers a reference position based on an electric signal output from the piezoelectric element 114.

Next, a reference position registration method by the CPU 116 will be described with reference to FIGS. First,
The cup-type grindstone 64 is moved toward the chuck table 52 by controlling the grindstone feeding device 70. When the cup-shaped grindstone 64 contacts the chuck table 52, the chuck table 52 is pushed by the cup-shaped grindstone 64 and is displaced in the axial direction, so that an electric signal is output from the piezoelectric element 114,
The position of the cup-shaped grindstone 64 output from the position sensor 120 when the electric signal is output is registered in the RAM 118 of the CPU 116 as a reference position. Then, simultaneously with the output of the electric signal, the grindstone feeding device 70 is controlled to stop the movement of the cup-shaped grindstone 64.

Thus, according to the reference position registration method, the reference position of the cup-shaped grindstone 64 can be registered automatically, so that an accurate reference position can be registered. Further, according to the present invention, since the movement of the cup-type grindstone 64 is stopped at the same time as the output of the electric signal from the piezoelectric element 114, it is possible to prevent the chuck table 52, the cup-type grindstone 64, and the grindstone feeding device 70 from being damaged. it can.

When the reference position of the cup-shaped grindstone 64 is registered as described above, the grinding of the wafer 26 by the cup-shaped grindstone 64 is started. In this case, the CPU 116 controls the grindstone feeder 70 based on the registered reference position and the movement position information of the cup-shaped grindstone 64 output from the position sensor 120 to grind the wafer 26 by a predetermined grinding allowance. I do.

In this embodiment, the piezoelectric element 114
Is provided between the housing 108 and the main body 12, but is not limited thereto, and may be provided at a connecting portion between the chuck table 52 and the rotating shaft 102 and a connecting portion between the rotating shaft 102 and the output shaft 106 of the motor 104. May be provided. That is, if it is a position for detecting the axial displacement of the chuck table 52,
The mounting position does not matter.

In this embodiment, an example in which the present invention is applied to a surface grinding apparatus for grinding the back surface of a wafer has been described. However, the present invention is not limited to this, and the present invention may be applied to other surface grinding apparatuses for workpieces.

[0031]

As described above, according to the surface grinding apparatus of the present invention, the reference position of the grinding wheel can be automatically registered, and the accurate reference position can be registered. Further, according to the present invention, since the detection signal is output from the displacement detection means and the movement of the grinding wheel is stopped by controlling the grinding wheel feeding means, it is possible to prevent the chuck table, the grinding wheel, and the grinding wheel feeding means from being damaged. Can be.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a surface grinding apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of the surface grinding apparatus shown in FIG. 1;

FIG. 3 is a longitudinal sectional view showing the vicinity of a chuck table showing a mounting structure of a piezoelectric element.

FIG. 4 is a block diagram showing a control system of the surface grinding device shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Surface grinding apparatus 12 ... Main body 14 ... Cassette storage stage 16 ... Alignment stage 18 ... Rough grinding stage 20 ... Finish grinding stage 22 ... Cleaning stage 26 ... Wafer 52, 74 ... Chuck table 114 ... Piezoelectric element 116 ... CPU

Claims (2)

[Claims] 1. A grinding device body, a chuck table provided on the grinding device body and holding a work, a grinding wheel pressed against the work held on the chuck table to grind the work, and a grinding wheel mounted on the chuck table. Grinding wheel feeding means for moving forward and backward, position detecting means for detecting the moving position of the grinding wheel, displacement detecting means provided on the chuck table for detecting the axial displacement of the chuck table, and grinding by controlling the grinding wheel feeding means. By moving the grinding wheel toward the chuck table, the grinding wheel is brought into contact with the chuck table and the position of the grinding wheel when the detection signal is output from the displacement detecting means is registered as a reference position, and detected from the displacement detecting means. Control means for stopping the movement of the grinding wheel by controlling the wheel feeding means when the signal is output; Surface grinding apparatus according to claim Rukoto. 2. A surface grinding apparatus according to claim 1, wherein said displacement detecting means is a piezoelectric element provided between said grinding apparatus main body and said chuck table.