JP3189246B2 - High flatness polishing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for polishing a substrate having high parallelism and high flatness, such as a semiconductor wafer substrate, a glass substrate for optical components, and a composite substrate.

[0002]

2. Description of the Related Art FIG. 4A is a top view showing a conventional polishing apparatus, and FIG. 4B is a front view thereof. That is, a polishing platen 4 that rotates by mounting a polisher or wrap holding 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 processed by causing the workpiece to move relative to the polishing platen 4 while pressing the workpiece with the workpiece support 5.

However, in order to process a substrate with high parallelism and high flatness, the following several measures have been considered. First, as the first rotation 1 of the workpiece, the workpiece is rotated at the same rotation speed as that of the polishing platen 4. By doing so, the relative speed of the polishing platen 4 and the workpiece throughout the workpiece becomes the same as the relative speed at the rotation center of the workpiece and its direction (perpendicular to the radius of the polishing table 4). The processing speed in polishing is experimentally considered to be proportional to the relative speed and the pressing force. By doing so, the same processing speed is achieved over the entire surface of the workpiece, and high parallelism is realized.

Considering the trajectory of the workpiece on the polishing table 4 as a second point, the circumference of the polishing table 4 passing through the center of the workpiece and the circumference passing through the peripheral portion are different from those of the workpiece for the same processing time. Contact time is different. Due to this effect, the central portion of the workpiece is processed into a convex shape. To eliminate this effect, generally,
As the swing 2 of the workpiece, the polishing platen 4 is reciprocated in the radial direction while rotating the workpiece.

The third point is that the frictional force 3 due to polishing is determined by the relative speed between the workpiece and the polishing platen 4, the frictional force generated by pressing them, and the distance between 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. Generally, the polisher mounted on the polishing platen 4 exhibits a non-linear elasticity with respect to pressing, so that if such a tilt occurs, a large pressing will occur in the peripheral portion against others. As a result, the processing speed of the peripheral portion increases, and the central portion of the polished substrate becomes convex. In order to prevent this, a method has been considered in which the support point is brought as close as possible to the polishing platen 4 to reduce the moment.

[0006]

Even if the above first and second measures are taken and the support point is lowered as much as possible at the third point, it is possible to reduce the moment to zero by only reducing the moment. I can't.

The present invention has been made in view of the above circumstances, and can eliminate a moment generated by a processing resistance between a workpiece and a polishing platen generated during polishing, and can reduce a processing pressure applied to the workpiece to the entire processing surface. High parallelism,
An object of the present invention is to provide a polishing apparatus capable of performing polishing with high flatness.

[0008]

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

The high flatness polishing apparatus of the present invention has gap detectors at two different heights instead of the force detectors.
And a control unit for driving the actuator so that the workpiece support stands upright on the polishing platen based on the two gap detectors and a clearance detection signal of the workpiece support. .

[0010] The high flatness polishing apparatus of the present invention further comprises a polisher or lap for holding abrasive grains, a rotating polishing platen, a workpiece support for supporting the workpiece, and a second rotating workpiece support. In a polishing apparatus comprising a pair of guide rollers and a casing surrounding a polishing platen, a second pair of guide rollers is further provided at a position opposed to the first pair of guide rollers with a workpiece support interposed therebetween. A shaft having a fulcrum at a support portion fixed to the casing, having a rotatable arm at the fulcrum, and restraining the first and second pair of guide rollers at both ends of the arm in a freely rotatable manner. It is characterized by having.

Therefore, in the present invention, the moment is applied by applying a fixed ratio of force to the resistive force caused by the frictional force applied to the support point as a reverse moment at a specific distance from the polishing platen different from the support point. Remove. The method of counter-moment loading is to monitor the moment situation first, and to apply an external force corresponding to the force at a point different in height from the support point to cancel the moment. Second, use a lever or the like. In this method, a part of the force applied to the support point is applied so as to cancel the reverse moment.

By applying a reverse moment, the moment force applied to the work surface of the workpiece can be eliminated, whereby the polisher is uniformly deformed over the entire contact area between the work surface and the polisher, and a uniform load is generated. By applying a uniform load to the processing surface in this manner, an equal processing speed can be realized over the entire processing surface, and high flatness polishing 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, wherein a moment due to machining resistance is monitored by a load cell or a gap sensor, and a reverse moment is generated by an actuator. That is, a polishing platen 4 that rotates by mounting a polisher or wrap that holds abrasive grains, a workpiece support 5 that supports a workpiece 6, and a first pair of guides that rotates the workpiece support 5. A roller 7 and a workpiece support 5
And a second pair of guide rollers 8 at a position opposed to the first guide roller 7 with the first pair of guide rollers 7 therebetween. The first pair of guide rollers 7 detects a force applied in a tangential direction of the polishing platen 4. It has a load cell (force detector) 9 and the second pair of guide rollers 8 has an actuator 10 so that the moment acting on the workpiece support 5 based on the detection signal of the load cell 9 is made zero. A control unit 20 for driving the actuator 10 is provided. Reference numeral 14 denotes 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 a reverse moment is applied.
The support is performed by a first guide roller 7, and the workpiece support 5 is rotated at the same rotation speed as the polishing platen 4 by correcting and rotating the guide roller 7 by a motor. However, the guide roller 7 may be rotated spontaneously by the frictional force between the workpiece 6 and the polishing platen 4 without performing the correction rotation. A load cell 9 is provided near the fulcrum of the guide roller 7 to measure the processing resistance in the radial direction with respect to the polishing platen 4. Here, as a method of monitoring the moment, instead of the load cell 9, the gap sensors 14 are provided at two places having different heights, and the two gap sensors 14 are provided.
And a control unit 20 that drives the actuator 10 so that the workpiece support 5 stands upright on the polishing platen 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 inclination of the workpiece support 5 is measured by providing two upper and lower capacitance type gap sensors 14. On the other hand, a second guide roller 8 is installed at a height twice as high as the guide roller 7 and the polishing platen 4 so as to be opposite to the guide roller 7.
The guide roller 8 is fixed via an actuator 10 as shown in the figure. In this case, in the actual machining, a half of the measured frictional force is applied to the second guide roller 8 to generate a reverse moment and remove the moment applied to the machining surface.

FIG. 2 is a front view showing another embodiment of the present invention, in which a part of the opposing force applied to the first guide roller is transmitted to the second guide roller to control the moment. That is, a polishing platen 4 that rotates by mounting a polisher or wrap 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 casing 30 surrounding the polishing platen 4
And 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, and a fulcrum support portion 16 fixed to the casing 30. A fulcrum 12, and a rotatable arm 11 at the fulcrum 12.
A pair of guide rollers 7 and a second pair of guide rollers 8 are constituted by shafts 17 for freely rotating.

FIG. 2 shows another method of applying a reverse moment. The guide roller 7 for supporting the frictional force generated on the workpiece 6 is attached to an 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 the arm 11. During the polishing, the workpiece support 5 pushes the first guide roller 7 by the frictional force. Part of this force is arm 11
To the second guide roller 8, where a reverse moment is generated with respect to the workpiece support 5. Axis 17 is arm 1
1 and the guide roller 7 are rotatably restrained.

In the above, the method of applying a load to the polished workpiece has been described for the case of a static load. However, these methods can naturally be applied to the case of a forced load by pneumatic pressure, hydraulic pressure or the like. For example, if the upper portion of the workpiece support shown in FIG. 1 is pressurized via an airbag, a water bag, or the like, it is possible to avoid receiving a force in the direction parallel to the polishing platen from the pressurizing portion and control the moment. be able to. FIG.
Is to monitor the moment by a strain gauge and control the moment by an actuator. That is, the load and strain in the vertical direction of the pressure axis due to frictional force are measured by a strain gauge (strain gauge) 13 or the like attached to the axis to which the pressure 15 has been added, and the actuator 10 is actuated by the lower guide roller 7 so as to cancel the load. The moment is negated by pressing through the. In the drawings, the same portions are denoted by the same reference numerals and description thereof will be omitted.

[0018]

As described above, according to the present invention, a reverse moment is actively applied to the machining resistance generated between the workpiece and the polishing platen generated during polishing and the moment generated between the supporting points thereof. Polishing with high flatness, for example, within 1 μm, can be realized by applying a uniform processing pressure over the entire processing surface.

[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 workpiece, 2 ... swing of a workpiece, 3 ... frictional force by polishing, 4 ... polishing platen, 5 ... workpiece support, 6 ... workpiece, 7 ... first guide roller, 8 ... Second guide roller, 9 load cell, 10 actuator, 11 arm, 12 fulcrum, 13 strain gauge (strain gauge), 14 gap sensor, 15 pressurization, 16 fulcrum support, 17 shaft , 20 ... Control unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-299739 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24B 37/00-37/04 H01L 21 / 304 622

Claims (3)

(57) [Claims] 1. A polishing platen that rotates with a polisher or wrap holding abrasive grains, a workpiece support that supports a workpiece, and a first pair of guide rollers that rotates 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 a force applied in a tangential direction of the polishing platen, and the second pair of guide rollers has an actuator, and the workpiece is formed based on a 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 the support is reduced to zero. 2. The high flatness polishing apparatus according to claim 1, wherein a gap detector is provided at two places having different heights in place of the force detector, and a clearance between the two gap detectors and the workpiece support. A high flatness polishing apparatus, comprising: a control unit that drives the actuator so that a workpiece support stands upright on a polishing platen based on a detection signal. 3. A polishing platen that rotates with a polisher or wrap holding abrasive grains, a workpiece support that supports a workpiece, a first pair of guide rollers that rotate the workpiece support, and polishing. A polishing apparatus comprising a casing surrounding the surface plate, further comprising a second pair of guide rollers at a position opposed to the first pair of guide rollers with the workpiece support interposed therebetween, and fixed to the casing. A high plane having a fulcrum at the supporting portion, a rotatable arm at the fulcrum, and a shaft at both ends of the arm for freely restraining the first and second pair of guide rollers. Degree polishing equipment.