JPH10277928A - Polishing equipment - Google Patents

Abstract

(57) Abstract: A polishing apparatus capable of uniformly polishing the entire surface of a semiconductor wafer. A semiconductor wafer (3) is placed on a flexible sheet (1).
6) and air pressure through the backing pad (8), a ring plate (17) is provided outside the wafer (3), and the wafer polishing surface (4) is provided by a ring plate height adjusting mechanism (18). And the height of the ring lower surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus used in a step of mechanically flattening the surface of a semiconductor wafer in a semiconductor manufacturing process, and more particularly to a polishing apparatus excellent in characteristics for uniformly polishing the entire surface of a semiconductor wafer. About.

[0002]

2. Description of the Related Art As a conventional polishing apparatus, for example,
As described in JP-A-91058, a method has been used in which a semiconductor wafer is held on a rigid holding plate having good flatness and a surface of a polishing pad attached to a surface plate having good flatness is slid.

[0003]

The prior art described above is based on the idea that the flatness of the semiconductor wafer can be achieved by improving the flatness of the surfaces of the holding plate and the surface plate.
However, in sliding polishing between a polishing pad and a semiconductor wafer under a condition where a large load is applied, since the polishing pad in contact with the wafer is compressed, the polishing pad in which the end of the wafer is not compressed and deformed is used. Since the wafer moves while hitting the surface, there is a problem that the peripheral portion of the wafer is polished more than the central portion (so-called peripheral sag occurs).

An object of the present invention is to provide a polishing apparatus suitable for uniformly polishing the entire surface of a semiconductor wafer.

[0005]

As a first method for achieving the above object, in a semiconductor wafer holding structure, air pressure is applied by an air jet to a polishing pad outside a wafer and near a wafer end. It is. By compressing the polishing pad near the wafer edge by the air pressure near the wafer edge and adjusting the height of the polishing pad to the height of the portion where the wafer is in contact, non-uniform polishing of the wafer peripheral portion does not occur.

As a second method for achieving the above object, in a wafer holding structure, a ring is provided outside a wafer, and the height of the ring is adjusted so that the lower surface of the ring and the wafer polishing surface are at the same height. Provide a mechanism. Since the height of the wafer polishing surface and the lower surface of the ring are aligned, uneven polishing of the wafer peripheral portion does not occur.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic view of the entire polishing apparatus to which the first embodiment is applied. FIG. 2 is a vertical sectional view showing the wafer holding structure in an enlarged manner in the thickness direction. A polishing pad 2 is stuck on a disk-shaped flat platen 1.
A polishing liquid is caused to flow on the polishing pad 2. The semiconductor wafer 3 is mounted on the wafer holder 5 such that the surface 4 to be polished contacts the polishing pad 2. The wafer holder 5 has an air flow path 6, and has a structure in which a rigid flat surface 7 having good flatness applies a load to the back surface of the wafer 3 with the backing pad 8 interposed therebetween. A ring-shaped air nozzle 9 is provided near the outside of the wafer 3 and applies air pressure to the polishing pad 2 by an air jet. As the backing pad, for example, a polyurethane sheet or a rubber sheet having a thickness of about 0.5 mm is used. The elastic strength of the material is not more than half the elastic strength of the polishing pad.

As the polishing pad 2, foamed polyurethane, nylon or the like having a thickness of about 1 mm is used. It is desirable to provide a groove or a hole on the surface of the polishing pad 2 so that the polishing liquid is easily held on the polishing pad 2. The wafer holder 5 swings on the platen 1 while pressing the wafer 3 against the polishing pad 2 while applying a load 10 (arrow) 11 and further rotates 12
I do. The platen also rotates 13.

As a result, the polishing surface 4 of the wafer 3 moves while being rubbed against the surface of the polishing pad 2 and is polished. As shown in FIG. 2, the polishing pad 2 in contact with the wafer 3 is compressed by the pressing load, and the polishing pad 2 is also compressed by air pressure near the outer edge of the wafer.
Is compressed and the surface of the polishing pad 2 is substantially flat, so that the entire surface of the wafer can be uniformly polished without being affected by the edge of the wafer.

[0010] Instead of the air nozzle, an air chamber for applying air pressure to the polishing pad surface may be provided near the wafer.

A second embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a vertical cross-sectional view of the wafer holding structure portion enlarged in the thickness direction. The wafer holder 5 has an air passage 14
, And an air chamber 15, and a structure for applying a load to the wafer 3 via the flexible sheet 16 and the backing pad 8. A ring plate 17 is provided outside the wafer 3. Height adjustment mechanism 1 utilizing air pressure on sheet 16 at the outer periphery of wafer
8 is provided so that the height of the lower surface of the ring plate 17 can be adjusted to match the wafer polishing surface 4. A retainer ring 19 is provided near the outside of the wafer 3. There is also a component 20 for attaching the sheet 16 to the wafer holder 5 and fixing the position of the ring plate 17. By matching the height of the lower surface of the ring plate 17 with the height of the wafer polishing surface 4, the entire surface of the wafer can be uniformly polished without the influence of the wafer edge.

The flexible sheet 16 and the backing pad 8 absorb the influence of foreign matter between the wafer 3 and the backing pad 8 and the influence of variations in the thickness of the wafer 3, and apply the entire surface of the wafer to the polishing pad 2 with a uniform pressure. Since the pressing is performed, the entire surface of the wafer is uniformly polished. The same effect can be obtained even when a gel-like soft material or liquid is sealed in the air chamber 15.

A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a vertical sectional view showing the wafer holding structure in an enlarged manner in the thickness direction. The wafer holder 5 has an air passage 14
, And an air chamber 15, which is configured to apply a load to the wafer 3 via the flexible sheet 21 and the backing pad 8. The sheet 21 has a pot-like shape, and is attached to the wafer holder 5 by attaching parts 22.

A pressing component 23 is provided outside the wafer 3, and a height adjusting mechanism 24 using air pressure is provided. The lower surface 25 of the pressing component 23 and the wafer polishing surface 4 have the same height. It can be adjusted.
By matching the height of the lower surface 25 of the pressing component 23 with the height of the wafer polishing surface 4, the entire surface of the wafer can be uniformly polished without the influence of the wafer edge.

[0015]

According to the present invention, the influence of the edge of the wafer can be eliminated, the pressure of pressing against the polishing pad against the wafer can be made uniform over the entire surface of the wafer, and the polishing rate over the entire surface of the wafer can be made uniform. Become. Therefore, there is an effect that the defect rate at the time of manufacturing a semiconductor is reduced, and a highly reliable and highly integrated semiconductor device can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view of a polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of a wafer holding structure of the polishing apparatus according to the first embodiment of the present invention.

FIG. 3 is an enlarged vertical sectional view of a wafer holding structure of a polishing apparatus according to a second embodiment of the present invention.

FIG. 4 is an enlarged vertical sectional view of a wafer holding structure of a polishing apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Surface plate, 2 ... Polishing pad, 3 ... Semiconductor wafer, 4 ... Polishing surface, 5 ... Wafer holder, 6 ... Air flow path, 7 ... Rigid surface, 8 ... Backing pad, 9 ... Air nozzle, 10 ... Load , 11 ... swing, 12, 13 ... rotation, 14 ... air flow path,
15 ... air chamber, 16 ... seat, 17 ... ring plate, 18 ...
Height adjusting mechanism, 19: retainer ring, 20: fixed component, 21: seat, 22: mounting component, 23: pressing component, 24: height adjusting mechanism, 25: lower surface of the pressing component.

Claims (1)

[Claims] A semiconductor wafer attached to a wafer holder;
In the polishing apparatus for polishing the polishing surface of the semiconductor wafer by moving while pressing the polishing surface of the semiconductor wafer against the surface of the sheet-like polishing pad adhered to the surface plate, the polishing pad near the semiconductor wafer is pressed by air pressure. A polishing apparatus having a compression mechanism.