JP2945110B2 - Carrier fixed position stop method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lapping apparatus for grinding a substrate for producing a semiconductor wafer, a hard disk or the like, and more particularly to a method for stopping a carrier at a fixed position.

(Prior Art) Conventionally, in this type of lapping apparatus, an upper and lower platen rotated by a variable speed motor, a sun gear and an internal gear rotated by a servomotor, and a carrier meshed with the sun gear and the internal gear are used. Prepared, after the worker holds the substrate of the workpiece on the carrier,
The substrate was ground with upper and lower platens for pressing. When the grinding is completed, the operator removes the substrate from the carrier and holds the new substrate on the carrier to perform the grinding.

(Problems to be Solved by the Invention) However, in the above-mentioned lapping apparatus, since the supply and recovery of the substrate must be performed manually, there is a case where the replacement takes time and the work time for grinding is delayed.
In order to solve this drawback, a method of automatically supplying and collecting the above-mentioned substrates without using humans by using a robot or an automatic exchanger may be considered.However, in the above method, the robot or the automatic exchanger uses the substrate as a carrier. In order to supply or recover the carrier, it is necessary to stop the carrier at a fixed position, and there is a problem that it is necessary to improve the stopping accuracy.

The present invention has been made in view of the above problems, and has as its object to provide a fixed position stopping method of a carrier that can accurately stop a carrier holding a substrate at a fixed position and improve stopping accuracy. I do.

(Means for Solving the Problems) In the present invention, there is provided at least two carriers which hold a workpiece and rotate by a predetermined drive system, and pressurize the workpiece held by the carrier. In a lapping apparatus for grinding with a platen, the drive system is driven and controlled according to the rotation speed of the platen to rotate the carrier, and when the grinding of the workpiece is completed, the platen and the drive system are ground. Drive control at a lower speed to detect one of the carriers, detect the moving distance of the carrier from the detection position, and when the moving distance of the carrier reaches a predetermined position, stop the movement of the carrier, When detecting the next carrier, the carrier is rotated by synchronizing the rotation speeds of the platen and the drive system.

(Operation) After the grinding of the workpiece is completed, the carrier is detected, and the moving distance of the carrier is detected. When the moving distance reaches a predetermined position, the carrier is stopped.

Therefore, the carrier can be accurately stopped at a fixed position.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a main part configuration diagram showing an example of a double side wrapping device according to the present invention, and FIG. 2 is a plan view showing an upper part of a lower platen shown in FIG. In the figure, an upper platen 11 is supported by an up-and-down cylinder (not shown), comes into contact with and separates from a lower platen 13 described later, and rotates in the direction of arrow A by a variable speed motor described later. A grindstone 12 is attached to the lower surface of the upper stool 11 and rotates in conjunction with the upper stool 11.

The lower platen 13 is rotated in the direction of arrow B by a variable speed motor. A grinding wheel 14 is attached to the upper surface of the lower stool 13 and rotates in conjunction with the lower stool 13. Further, a plurality of substrates 16 held by a plurality of carriers 15 are mounted on the upper part of the grindstone 14.

In the embodiment, five carriers 15 are arranged at equal intervals of 72 °, and the outer peripheral portion of the carrier 15 is meshed with the ungear 17 and the internal gear 18. The sun gear 17 and the internal gear 18 are independently rotated in the direction of arrow B by a servo motor described later, and the carrier 15 rotates and revolves in the direction of arrow B by this rotation.

Therefore, when grinding the substrate 16, the upper platen 11 is lowered, the substrate 16 is pinched by the grindstones 12 and 14, and the upper platen 11 and the lower platen 13
Rotate in opposite directions, and at the same time
15 rotates by the rotation of the sun gear 17 and the internal gear 18 while revolving in the same direction as the lower surface plate 13. As a result, the substrate 16 held by the carrier 15 is
The rotations of the carriers 1 and 13 and the movements of the carrier 15 in four directions of rotation and rotation are given, and the upper and lower surfaces of the substrate 16 are ground, and predetermined lapping eyes (streak-shaped eyes) are formed on the surface.

An optical sensor 19 is provided at a predetermined position above the carrier 15 and the internal gear 18. The optical sensor 19 is a reflection-type photoelectric switch focused on the tooth portion of the carrier 15, and the carrier 15 at the predetermined position after the grinding is completed.
Detect teeth. The detection point C is a point where the teeth of the internal gear 18 are not detected as shown in FIG. 3, and when the carrier 15 revolves after the grinding is completed and reaches the detection point C, the optical sensor 19 is turned on. Control circuit (CP
U) Output to 20 (see FIG. 1).

The CPU 20 has a counter function in a control circuit for controlling the grinding operation, and excites each of the relay circuits Ry1 to Ry8 in accordance with the counted grinding operation, thereby setting a switch to be described later.
On / off control of R1y to Ry8 is performed. That is, in the state of the grinding start, the relay circuits Ry1, Ry4, and Ry6 are excited, and when the end of the grinding is detected from the counted grinding time, the relay circuits Ry2, Ry4, and Ry6 are excited, In the state where the detection signal of the ON state is taken from the optical sensor 19 after the grinding is completed, the relay circuits Ry3, Ry4,
When Ry6 and Ry8 are excited and the lower platen 13, sun gear 17 and internal gear 18 are synchronized, the relay circuit
Ry2, Ry5, Ry7, Ry8 are excited.

FIG. 4 is a block diagram of a motor drive system according to the present invention. In the figure, the rotation speed setting circuits 22 to 24 are circuits for setting the rotation speed of the variable speed motor 21 that rotates the upper and lower platens 11 and 13 in each of the above-described states, and the rotation speed setting circuits 29 and 30 , A circuit for setting the rotation speed of a servo motor 28 for rotating the sun gear 17, and the rotation speed setting circuits 35 and 36 are circuits for setting the rotation speed of the servo motor 34 for rotating the internal gear 18. is there.

The rotation speed setting circuit 22 controls the rotation speed (60
[Rpm]), and a rotation speed setting circuit 23 sets a reference voltage corresponding to the rotation speed at the time of low speed after the grinding and the synchronization (6 [rpm]), and sets the rotation speed. The circuit 24 sets a reference voltage corresponding to the rotation speed (0.6 [rpm]) at the very low speed after the detection of the carrier position. The set reference voltage is output to the lamp circuit 25 via the switches Ry1 to Ry3. The switches Ry1 to Ry3 are turned on by the excitation of the above-described relay circuits Ry1 to Ry3, respectively.

The ramp circuit 25 is an integrator, and the rotation speed setting circuits 22 to 24
The rising and falling voltages corresponding to the reference voltage set in step (1) are connected to the drive unit 26,
The data is output to the ratio setting circuit 31 and the ratio setting circuit 37 in a linearly inclined manner (see FIGS. 5 and 6).

The switch Ry9 is turned on at the time of normal operation such as grinding, and is turned off only when a relay circuit Ry9 described later is excited.

The drive unit 26 includes a reference voltage from the ramp circuit 25 and a variable speed motor 21 which is detected and fed back by the speed detection unit 27 attached to the output shaft of the variable speed motor 21.
The rotation speed (indicated by the voltage value) of the motor
21 is driven at the set rotation speed.

The rotation speed setting circuit 29 sets the voltage during normal grinding, and the rotation speed setting circuit 30 sets the voltage during tuning.
The set voltage is supplied to the ratio setting circuit 31 via switches Ry4 and Ry5.
Is output to The switches Ry4 and Ry5 are turned on by the excitation of the above-described relay circuits Ry4 and Ry5, respectively.

The ratio setting circuit 31 is a circuit in which a ratio for outputting a reference voltage to the drive unit 32 is set.The ratio to the reference voltage taken from the rotation speed setting circuit 29 or 30 and the reference voltage from the ramp circuit 25 Sets the reference voltage to be output to the drive unit 32.

The drive unit 32 takes in the reference voltage from the ratio setting circuit 31 and drives the motor 28 at the set rotation speed.

The rotation speed setting circuit 35 sets a voltage for normal grinding, and the rotation speed setting circuit 36 sets a voltage for tuning.
The set voltage is supplied to the ratio setting circuit 37 via switches Ry6 and Ry7.
Is output to The switches Ry6 and Ry7 are turned on by the excitation of the above-described relay circuits Ry6 and Ry7, respectively.

The ratio setting circuit 37 is a circuit in which a ratio for outputting a reference voltage to the drive unit 38 is set.The ratio to the reference voltage taken from the rotation speed setting circuit 35 or 36, the reference voltage from the ramp circuit 25, Sets the reference voltage to be output to the drive unit 38.

The drive unit 38 takes in the reference voltage from the ratio setting circuit 37 and drives the motor 34 at the set rotation speed.

Rotational position detectors (PG) 33, 39 such as resolvers or encoders are attached to the output shafts of the servomotors 28, 34, respectively, and indicate the rotational positions (indicated by the number of pulses) of the servomotors 28, 34. Outputs a pulse signal,
For accuracy, for example, a value obtained by ORing both outputs is output to the preset counter 40 via the switch Ry8.
The switch Ry8 is a switch for starting counting that is turned on by the excitation of the above-described relay circuit Ry8.

The reason why the PG is attached to the output shafts of the servomotors 28 and 34 is that the carrier 15 is stopped at a fixed position by the sun gear.
The rotation of the carrier 15 revolving around the sun gear 17 is S, the sun gear ratio is ZS, and the internal gear rotation is I. , Internal gear ratio
Assuming that ZI, {(S × ZS) + (I × ZI)} / (ZS + ZI) (1) Further, the number of the pulse signals can be arbitrarily set depending on the device to be used. In the embodiment, it is assumed that 1000 pulses are output for one rotation of the sun gear 17 or the internal gear 18.

The pulse signal from the PG 33 or 39 is input to the preset counter circuit 40. Here, when the pulse signal is input to the PG 33, the preset value stored in the memory or the like is fetched, the counting of the pulse signal is started, and the count value is counted. Is a line stop command counter that excites the relay circuit Ry9 to stop the carrier at a predetermined position when the preset value matches the preset value. Here, the number of revolutions of carrier 15 is 0.19
7 [rpm], the stop angle of carrier 15 is 90 ° (see Fig. 2)
Then, the preset value x of the counter is as follows: x = (90 ° / 360 °) × 1000 [plus] × S (2) where S is expressed by the following equation (1): {0.197 [rpm] × (ZS
+ ZI) − (I × ZI)｝ / ZS, x in equation (2) is: x = (90 （/ 360 ゜) × 1000 [plus] × ｛0.197 [rp
m] × (ZS + ZI) − (I × ZI)｝ / ZS.

Next, the operation of stopping the carrier at a fixed position according to the present invention will be described with reference to FIGS. 5 and 6. FIG.

First, when an instruction to grind a substrate is issued, the CPU 20 excites the relay circuits Ry1, Ry4, Ry6 to turn on the switches Ry1, Ry4, Ry6 and counts the grinding time. Further, the preset counter 40 turns on the switch Ry9.

The reference voltage from the rotation speed setting circuit 22 is the switch Ry
1, output to the drive unit 26 via the ramp circuit 25 and the switch Ry9, and to the drive units 32 and 38 via the ratio setting circuits 31 and 37. Each drive unit 26, 32, 38
Drives the respective motors in accordance with the set rotational speeds, sets the platens 11 and 13 to 60 [rpm], and sets the sun gear 17 to 26
[Rpm], the internal gear 18 is rotated at a constant speed of 18 [rpm].

When the CPU 20 detects the completion of grinding, the relay circuit R
The switches Ry2, Ry4, and Ry6 are turned on by exciting y2, Ry4, and Ry6, and the optical sensor 19 detects the carrier 15. Further, as shown in FIG. 5, the rotation speed is reduced obliquely linearly by the reference voltage that is output linearly from the ramp circuit 25, and the surface plates 11, 13, the sun gear 17, and the internal gear 18 are respectively moved. 6 [rpm], 2.6 [rpm], 1.8 [r.
pm].

When the optical sensor 19 detects the carrier 15, the CPU 20 excites the relay circuits Ry3, Ry4, Ry6, and switches Ry3, Ry
4. Turn on Ry6 and set the platens 11,13, sun gear 17, and internal gear 18 to 0.6 [rpm] and 0.26 [rp, respectively.
m] and 0.18 [rpm]. At the same time, the relay circuit Ry8 is excited to turn on the switch Ry8, and the preset counter 40 counts the moving distance of the carrier 15 after the carrier detection.

When the count reaches a predetermined count value (fixed position), the preset counter 40 excites the relay circuit Ry9, turns off the switch Ry9, and instantaneously stops the motors 21, 28, and 34. Thus, the surface plates 11, 13, the sun gear 17, and the internal gear 18 stop at that position, and accordingly, the carrier 15 can also stop at the fixed position.

In order to stop one carrier at a fixed position and then stop the next carrier at a fixed position, a relay circuit Ry is required so that the lapping eyes formed on the surface of the substrate are not disturbed.
2. Energize Ry5, Ry7, turn on switches Ry2, Ry5, Ry7, and rotate platens 11, 13, sun gear 17, and internal gear 18 in synchronization with the same speed of 6 [rpm]. . Then, the optical sensor 19 detects the next carrier 15.

When the optical sensor 19 detects the carrier 15, the relay circuit Ry
When the switch 8 is turned on, the switch Ry8 is turned on, the relay circuit Ry3 is switched to the fine speed setting (0.6 [rpm]), and the preset counter 40 counts the moving distance of the carrier 15 after the carrier is detected. As shown in FIG. 6, the reference voltage is output linearly as shown in FIG.
When the rotation speed decreases linearly and the count value reaches the preset value, the preset counter 40 sets the relay circuit Ry.
9 to excite switch 9
Stop 1,28,34. As a result, the surface plates 11, 13, the sun gear 17, and the internal gear 18 stop at that position, and the carrier 15 also stops at the fixed position.

In addition, since the installation position of the robot and the automatic exchange with respect to the wrapping machine may be different depending on the installation conditions and the like, the preset value of the preset counter is determined by how many times the optical sensor stops after the optical sensor is turned on. It is desirable to actually set the preset value to a predetermined value and stop the carrier, and then calculate the angle of the deviation from the above-described formula of the carrier revolution to determine how many pulses should be corrected.

Therefore, in this embodiment, when the optical sensor detects the carrier after the grinding of the substrate, the rotation speed of the platen, sun gear, and internal gear is rotated at a fine speed of 1/50 to 1/100 of the grinding, and the carrier is rotated. Is reached, the surface plate, sun gear,
Since the internal gear is stopped instantaneously, the carrier can be accurately stopped at a fixed position.

(Effects of the Invention) As described above, the present invention has at least two carriers that hold a workpiece and rotate by a predetermined drive system, and presses the workpiece held by the carrier. In a lapping apparatus for grinding with a surface plate, the carrier is rotated by controlling the drive system in accordance with the rotation speed of the surface plate, and when the grinding of the workpiece is completed, the surface plate and the drive system are ground. When one of the carriers is detected by driving control at a lower speed than at the time, the moving distance of the carrier from the detection position is detected, and when the moving distance of the carrier reaches a predetermined position, the movement of the carrier is stopped. When detecting the next carrier, the carrier is rotated by synchronizing the rotation speeds of the platen and the drive system, so that the carrier holding the substrate is accurately stopped at a fixed position. Stopping accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing an example of a double side wrapping device according to the present invention, FIG. 2 is a plan view showing an upper part of a lower platen shown in FIG. 1, and FIG. Enlarged view, fourth
FIG. 5 is a block diagram of a motor drive system according to the present invention, FIG.
FIG. 6 is a diagram showing a change in the rotation speed of the carrier. 11,13… Surface plate, 12, 14… Whetstone, 15… Carrier, 16…
... board, 17 ... sun gear, 18 ... internal gear, 19
…… Optical sensor, 20… Control circuit (CPU), 21,28,34 ……
Motors, 22 to 24, 29, 30, 35, 36 ... Rotation speed setting circuit, 25
…… Lamp circuit, 26,32,38 drive unit, 40 …… Preset counter.

Claims (1)

(57) [Claims] 1. A lapping device for holding a workpiece and rotating at least two carriers by a predetermined drive system, wherein the lapping apparatus grinds the workpiece held by the carrier with a surface plate that presses the carrier. The carrier is rotated by controlling the drive system according to the rotation speed of the surface plate, and when the grinding of the workpiece is completed, the carrier and the carrier are controlled by driving the surface plate and the drive system at a lower speed than during grinding. And detecting the movement distance of the carrier from the detection position, and when the movement distance of the carrier reaches a predetermined position, stops the movement of the carrier and detects the next carrier. And rotating the carrier by synchronizing the rotation speeds of the platen and the drive system.