JPH09155731A - High-flatness polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the polishing of high parallelism and high flatness by eliminating a moment generated by the working resistance of a workpiece and a polishing board and uniformizing a working pressure applied to a workpiece over the whole surface of a worked surface. SOLUTION: This device has a second guide roller 8 in the opposite position to a first guide roller 7 for rotating a workpiece supporting body 5, the first guide roller 7 has a load cell 9 for detecting force applied in the direction of the tangential line of a polishing board 4, and the second guide roller 8 has an actuator 10. This device is also provided with a control part 20 for driving the actuator 10 so as to make a moment acting on the workpiece supporting body 5 zero on the basis of the detection signal of the load cell 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for highly parallel and highly flat substrates such as semiconductor wafer substrates, glass substrates for optical components, and composite substrates.

[0002]

2. Description of the Related Art FIG. 4 (a) is a top view showing a conventional polishing apparatus, and FIG. 4 (b) is a front view of the same. That is, a polishing platen 4 that rotates by mounting a polisher or a wrap that holds abrasive grains, a workpiece support 5 that supports a workpiece, and a first pair of guide rollers that rotate the workpiece support 5. 7
The workpiece is supported by the workpiece support 5 with respect to the polishing platen 4 while performing relative movement while pressing the workpiece.

However, the following several measures have been considered in order to process the conventional substrate to have high parallelism and high flatness. First, as the rotation 1 of the workpiece at the first point, the workpiece is rotated at the same rotation number as the rotation number of the polishing platen 4. By doing so, the relative speed of the polishing platen 4 and the work piece is the same in all directions of the work piece in the rotation center of the work piece and in the direction thereof (direction perpendicular to the radius of the polishing platen 4). Experimentally, the processing speed in polishing is said to be proportional to this relative speed and the pressing force, and by doing so, the same processing speed is achieved over the entire surface of the workpiece, and high parallelism is realized.

Considering the locus of the workpiece on the polishing platen 4 as a second point, the circumference of the polishing platen 4 passing through the center of the workpiece and the circumference passing through the periphery of the polishing platen 4 are regarded as the workpieces for the same processing time. Contact time is different. Due to this effect, the center part of the workpiece is processed into a convex shape. To eliminate this effect, in general,
As the swing 2 of the workpiece, the polishing platen 4 is reciprocally moved in the radial direction while rotating the workpiece.

The third point is the frictional force 3 caused by polishing, which is determined by the relative speed between the workpiece and the polishing platen 4, the frictional force generated by pressing them, and the distance from the support point of the workpiece and the polishing platen 4. It is a problem of the inclination of the workpiece due to the generated moment. In general, the polisher mounted on the polishing platen 4 exhibits non-linear elasticity with respect to pressing, so that if such an inclination occurs, a large pressing is generated in the peripheral portion against others. As a result, the processing speed of the peripheral portion is increased, and the center portion of the polished substrate becomes convex. In order to prevent this, a method of making the supporting point as close as possible to the polishing platen 4 and reducing the moment is considered.

[0006]

Even if the support points are lowered as much as possible at the third point while taking the measures for the above first and second points, the moment can be reduced to 0 by reducing the moment. You cannot do it.

The present invention has been made in view of the above circumstances, and it is possible to remove the moment generated by the processing resistance between the workpiece and the polishing surface plate generated during polishing, and the processing pressure applied to the workpiece is applied to the entire processing surface. High parallelism,
An object of the present invention is to provide a polishing apparatus that can perform polishing with high flatness.

[0008]

In order to achieve the above object, a high flatness polishing apparatus of the present invention is provided with a polishing platen for holding abrasive grains or a lap for rotating a polishing platen and a process for supporting a workpiece. A polishing device comprising a workpiece support and a first pair of guide rollers for rotating the workpiece support, further comprising a second pair of guides at a position facing the first guide roller with the workpiece support interposed therebetween. And a first pair of guide rollers having a force detector for detecting a force applied in a tangential direction of the polishing surface plate, and a second pair of guide rollers having an actuator. It is characterized by comprising a control unit for driving the actuator so that the moment acting on the workpiece support is made zero based on the detection signal.

The high flatness polishing apparatus of the present invention has gap detectors at two different heights instead of the force detector,
A control unit for driving the actuator so that the workpiece support is erected on the polishing platen on the basis of the two gap detectors and the clearance detection signal of the workpiece support is provided. .

Further, the high flatness polishing apparatus of the present invention comprises a polishing platen for holding abrasive grains, a polishing platen for rotating, a work support for supporting a work, and a work support for rotating the work support. A polishing device comprising a pair of guide rollers and a casing surrounding a polishing platen, further comprising a second pair of guide rollers at a position facing the first pair of guide rollers with a workpiece support interposed therebetween. A shaft having a fulcrum on a support fixed to the casing, having an arm rotatable at the fulcrum, and rotatably restraining the pair of first and second guide rollers at both ends of the arm. It is characterized by having.

Therefore, according to the present invention, a fixed ratio of force to the resistance force due to the frictional force applied to the supporting point is applied as a reverse moment to a specific distance from the polishing platen different from the supporting point, so that this moment is applied. Remove. For the load of reverse moment, first of all, the situation of moment is monitored, and at the point where the height is different from the supporting point, the external force according to the force is applied to cancel the moment, and secondly, the lever is used. In this method, a part of the force applied to the supporting point is applied so as to cancel the reverse moment.

By applying a reverse moment, the moment force applied to the machined surface of the workpiece can be removed, whereby the polisher is uniformly deformed over the entire contact portion between the machined surface and the polisher, and a uniform load is generated. By applying a uniform load to the machined surface in this manner, the same machining speed can be realized over the entire machined surface, and polishing with high flatness can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of the present invention, in which a moment due to machining resistance is monitored by a load cell or a gap sensor, and an inverse moment is generated by an actuator. That is, a polishing surface plate 4 that rotates by mounting a polisher or a wrap that holds abrasive grains, a workpiece support 5 that supports a workpiece 6, and a first pair of guides that rotate the workpiece support 5. It consists of a roller 7 and a workpiece support 5
A second pair of guide rollers 8 is provided at a position opposed to the first guide roller 7 with the first pair of guide rollers 7 interposed therebetween, and the first pair of guide rollers 7 detects the force applied in the tangential direction of the polishing surface plate 4. A load cell (force detector) 9 is provided, and a second pair of guide rollers 8 has an actuator 10 so that the moment acting on the workpiece support 5 is made zero based on the detection signal of the load cell 9. A control unit 20 that drives the actuator 10 is provided. Reference numeral 14 is a gap sensor (gap detector).

That is, FIG. 2 shows a type in which a frictional force applied to a support point is monitored and an inverse moment is applied.
The support is performed by the first guide roller 7, and the workpiece support 5 is rotated at the same number of revolutions as the polishing platen 4 by correcting and rotating the guide roller 7 by a motor. However, here, the guide roller 7 may be naturally rotated by the frictional force between the workpiece 6 and the polishing platen 4 without performing the corrective rotation. A load cell 9 is provided near the fulcrum of the guide roller 7 to measure the machining resistance in the radial direction with respect to the polishing platen 4. Here, as a method for monitoring the moment, instead of the load cell 9, the gap sensors 14 are provided at two different heights, and the two gap sensors 14 are provided.
Alternatively, the control unit 20 may be configured to drive the actuator 10 so that the workpiece support 5 is erected on the polishing surface plate 4 based on the clearance detection signal of the workpiece support 5.
That is, the inclination due to the moment may be measured, and the inclinations of the workpiece support 5 are measured by providing the electrostatic capacitance type gap sensors 14 at the upper and lower portions. On the other hand, a second guide roller 8 is installed at a height twice that of the guide roller 7 and the polishing platen 4 so as to oppose the guide roller 7.
The guide roller 8 is fixed via an actuator 10 as shown in the figure. In this case, in actual machining, a half of the measured frictional force is applied to the second guide roller 8 to generate a reverse moment and the moment applied to the machined surface can be removed.

FIG. 2 is a front view showing another embodiment of the present invention, in which a part of the counterforce applied to the first guide roller is transmitted to the second guide roller to control the moment. That is, a polishing surface plate 4 that rotates by mounting a polisher or a lap that holds abrasive grains, a workpiece support 5 that supports a workpiece 6, and a first 1 that rotates the workpiece support 5
A pair of guide rollers 7 and a case 30 surrounding the polishing platen 4.
And a fulcrum support portion 16 fixed to the casing 30 having a second pair of guide rollers 8 at a position facing the first pair of guide rollers 7 with the workpiece support 5 interposed therebetween. Has a fulcrum 12 and an arm 11 rotatable at the fulcrum 12, and the first 1 is attached to both ends of the arm 11.
The pair of guide rollers 7 and the second pair of guide rollers 8 are configured to have a shaft 17 that freely rotatably restrains them.

FIG. 2 shows another method of applying a reverse moment. The guide roller 7 that supports the frictional force generated in the workpiece 6 is attached to the arm 11 that freely rotates about a fulcrum 12 as shown in the figure. Also in this case, the guide roller 7 is forcibly rotated by the motor. A second guide roller 8 is provided at the other end of this arm 11. During the polishing process, the workpiece support 5 pushes the first guide roller 7 due to the frictional force. Part of this force is the arm 11
And is transmitted to the second guide roller 8 via the second guide roller 8 to generate a reverse moment with respect to the workpiece support 5. Axis 17 is arm 1
The tip end of 1 and the guide roller 7 are rotatably restrained.

In the above, as a method of applying a load to the polishing work, the case of static load is described, but of course, these can also be applied to the case of forced load by pneumatic pressure, hydraulic pressure or the like. For example, if the upper part of the workpiece support shown in FIG. 1 is pressed through an air bag, a water bag, etc., it is possible to avoid receiving a force from the pressing part in the direction parallel to the polishing platen and control the moment. be able to. FIG.
Is to monitor the moment with a strain gauge and to control the moment with an actuator. That is, the strain gauge (strain gauge) 13 attached to the shaft to which the pressure 15 is applied measures the load and strain in the direction perpendicular to the pressure axis due to the frictional force, and the actuator 10 is guided by the lower guide roller 7 so as to cancel it. The moment is canceled by pressing through. In the figure, the same parts are designated by the same reference numerals and the description thereof is omitted.

[0018]

As described above, according to the present invention, an inverse moment is actively applied to a machining resistance generated between a workpiece and a polishing surface plate during polishing and a moment generated between supporting points of the workpiece resistance. By applying a uniform processing pressure over the entire surface to be processed, it is possible to realize a high flatness, for example, a polishing process within 1 μm.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a front view showing another embodiment of the present invention.

FIG. 3 is a front view showing another example of another embodiment of the present invention.

FIG. 4A is a top view showing a conventional polishing apparatus, and FIG.
FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotation of a work piece, 2 ... Oscillation of a work piece, 3 ... Friction force by polishing, 4 ... Polishing platen, 5 ... Work piece support, 6 ... Work piece, 7 ... First guide roller, 8 ... Second guide roller, 9 ... Load cell, 10 ... Actuator, 11 ... Arm, 12 ... Support point, 13 ... Strain gauge (strain gauge), 14 ... Gap sensor, 15 ... Pressurization, 16 ... Support point support section, 17 ... Shaft , 20 ... Control unit.

Claims (3)

[Claims] 1. A polishing platen which is equipped with a polisher or a lap for holding abrasive grains and rotates, a workpiece support for supporting a workpiece, and a first pair of guide rollers for rotating the workpiece support. The polishing apparatus further includes a second pair of guide rollers at a position facing the first guide roller with the workpiece support interposed therebetween.
The pair of guide rollers has a force detector for detecting the force applied in the tangential direction of the polishing surface plate, and the second pair of guide rollers has an actuator, and the workpiece is processed based on the detection signal of the force detector. A high flatness polishing apparatus comprising a control unit for driving the actuator so that a moment acting on a support is made zero. 2. The high flatness polishing apparatus according to claim 1, wherein a gap detector is provided at two different heights instead of the force detector, and the gap between the two gap detectors and the workpiece support is provided. A high flatness polishing apparatus comprising a control unit that drives the actuator so that the workpiece support stands upright on a polishing platen based on a detection signal. 3. A polishing platen which is equipped with a polisher or a lap for holding abrasive grains and rotates, a workpiece support for supporting a workpiece, a first pair of guide rollers for rotating the workpiece support, and polishing. A polishing device comprising a casing surrounding a surface plate, further comprising a second pair of guide rollers at a position facing the first pair of guide rollers with the workpiece support interposed therebetween, and fixed to the casing. A high plane having a fulcrum on a supporting portion, an arm rotatable at the fulcrum, and shafts for rotatably restraining the pair of first and second guide rollers at both ends of the arm. Degree polishing equipment.