JPH07201788A - Semiconductor grinder - Google Patents

Abstract

PURPOSE:To grind the surface of a wafer at an even grind rate by using a grinding system in which an expandable elastic body covered with abrasive cloth is rotated on a different axis from that of the wafer that is rotating independently. CONSTITUTION:A semiconductor grinder comprises a rotating mechanism (2-5) that fixedly supports a workpiece 1 having fine irregularities at its surface, and a drive mechanism (6-8) for rotating a grinding tool 11 that includes an expandable elastic body 10 covered with abrasive cloth 9. The axes of rotation of the two mechanisms are not coincident with each other. The elastic body 10 can be expanded toward the workpiece by introducing liquid through a rotary joint into the hollow of the grinding spindle 6 fixed to a slider 14, which is movable horizontally. The slider 14 is connected to an X-slide table 16, and its movement is numerically controlled by a control box 19 for an AC servomotor 18 connected directly with a ball screw 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor polishing apparatus for flattening a wiring step generated in a wiring process in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a polishing process for flattening a wiring step of a semiconductor is performed by placing a silicon wafer 21 having a wiring step of a workpiece on a chuck 22 equipped with a pressing mechanism. Surface plate 2 that is fixed and has a rotation mechanism
It was carried out by applying a constant load to a polisher 24 made of a polishing cloth such as foamed polyurethane attached to No. 3 and supplying a polishing agent such as pH-adjusted colloidal silica.

[0003]

The silicon wafer 21 subjected to the wiring is warped because of the different linear expansion coefficients of silicon, the wiring material, and the insulating film material. In addition, the flatness of the back surface of the device surface is deteriorated in the processing history as compared with the unprocessed one. Therefore, when the device surface is to be restricted to a flat surface, the chuck 22 cannot be used as a reference in the above-described polishing apparatus, and therefore the silicon wafer 21 is pressed against the polisher 24. However, in this case, the pressure distribution in the wafer surface becomes non-uniform, so that the polishing rate also becomes non-uniform, and over-polishing or under-polishing portions are generated, which easily causes defects. Therefore, an object of the present invention is to provide a polishing apparatus capable of processing the surface of a wafer at a uniform polishing rate.

[0004]

In order to achieve the above object, a polishing apparatus of the present invention is configured such that a polishing tool having a polisher mounted on an elastic body having an internal pressure and a silicon wafer to be added are rotated respectively. Moreover, the position of the rotating shaft is displaced.

[0005]

With this structure, the polisher of the polishing tool is pressed against the silicon wafer to be processed at a constant pressure.
Further, since the positions of the respective rotary shafts are deviated, the relative motion with the polisher 24 occurs on the surface of the silicon wafer 21 due to the rotation of the respective shafts.

Further, since the axial shift amount can be varied during processing, the polishing shaft can be moved in accordance with the polishing rate distribution to process the central portion or outer peripheral portion of the wafer 21. Further, by rotating each axis at high speed, the relative speed is increased and the wafer 21 having irregularities due to the generated dynamic pressure is used.
It is possible to lower the adhesion of the polisher 24 so that the polisher or the polishing agent acts only on the convex portions of the wafer.

As a result, it becomes possible to polish and flatten the semiconductor.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a silicon wafer to be processed, which has a device such as wiring on its upper surface and has fine irregularities. The silicon wafer 1 is adsorbed or fixed to the chuck 3 attached to the end of the work rotating spindle 2 with a wax. The rotary spindle 2 is rotated by a motor 5 via a timing belt 4. On the other hand, on the side of the polishing tool, the polishing spindle 6 is rotated by the motor 8 via the belt 7. The shaft of the polishing spindle 6 is hollow, and a polishing tool 11 in which a polisher 9 is attached to an elastic body 10 is attached to the end portion on the work side.
A rotary joint 12 is attached to the other end of the elastic body so that the elastic body can be deformed toward the work by injecting fluid from the rotary joint 12 side. Fluid is 0.1 to 2 kgf with pressure gauge 13.
It is set to a predetermined pressure of / cm ² . The polishing spindle 6 and the motor 8 are fixed on a slider 14 and can be moved up and down by an air cylinder 15. Further, the slider 14 is attached to the X-axis slide table 16, and the movement amount of the AC servo motor 18 directly connected to the ball screw 17 can be numerically controlled by the control box 19.

In this state, polisher 9 is added to 60-3600.
rpm, the silicon wafer 1 is rotated at 60 to 3600 rpm, and pH-adjusted colloidal silica or cerium oxide is supplied as an abrasive to perform polishing. In particular, as the number of rotations is increased, the dynamic pressure generated by the fine unevenness of the wafer is increased, the convex portions are easily removed selectively, and the flattening is promoted. As described above, the flattening process of the semiconductor wafer can be performed.

[0011]

According to the semiconductor polishing apparatus of the present invention, the polisher attached as described above is pressed against the silicon wafer to be processed by an elastic body having an inward pressure with a constant pressure to rotate the silicon wafer to be processed. Since the polishing is also rotated, the polisher can perform flattening polishing at a uniform polishing rate within the wafer surface without being affected by the shape of the silicon wafer to be processed such as warpage.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a semiconductor polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of a conventional polishing apparatus

[Explanation of symbols]

 1 Silicon wafer 9 Polisher 10 Elastic body

Claims (3)

[Claims] 1. A mechanism for fixing and rotating a workpiece to which fine processing is applied to form irregularities and a mechanism for rotating a polishing tool having a polishing cloth attached to the surface of an elastic body having internal pressure. And a semiconductor polishing apparatus in which the respective rotation axes are displaced. 2. The semiconductor polishing apparatus according to claim 1, wherein the distance between the rotating shafts can be varied by numerical control during processing. 3. The tool and the work piece are rotated at a high speed, and the polishing cloth is caused to act on the work piece in a state of being in contact with the work piece by a dynamic pressure generated by the relative movement of the tool and the work piece. The semiconductor polishing apparatus described.