JP2628308B2 - Pressurizing head for flat polishing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a planar polishing apparatus for precisely polishing one side of a thin work such as a semiconductor wafer, wherein the work adhered to a mounting block is formed by removing the work from the block. The present invention relates to a pressurizing head for pressing against a surface plate through the pressurized head.

2. Description of the Related Art In a conventionally known planar polishing apparatus of this type, a mounting block to which a work is adhered is directly attached to a lower surface of a pressing head, and the pressing head rotates the work via the mounting block. And pressed against it.

However, during the processing of the work, heat is generated at the interface between the surface plate and the work due to friction between the work surface and the work, so that the surface plate, the mounting block, and the pressure head are variously thermally deformed, and it is difficult for a uniform pressing force to act on the work. As a result, there is a disadvantage that the polishing accuracy is reduced.

Therefore, a cooling chamber is defined inside the surface plate and the pressure head, and polishing is performed while supplying cooling water to the cooling room, thereby preventing a temperature rise of the surface plate, the pressure head, the mounting block, and the like. In order to prevent such thermal deformation, it has been proposed (for example, Japanese Utility Model Publication No. 60-2117).
However, even with such a cooling method, it is difficult to completely prevent the above-mentioned thermal deformation, and in fact, it has not been possible to obtain a sufficient effect. Moreover, if it is attempted to completely prevent thermal deformation by such a cooling method, not only the structure becomes complicated, but also the temperature control of the cooling water is inevitably complicated.

[Problems to be Solved by the Invention] An object of the present invention is to compensate for thermal deformation of a surface plate, a pressure head, a mounting block, etc., so that a pressure from a pressure head is always uniformly applied to a work. Therefore, the object is to improve the polishing accuracy.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a method in which a flexible pad is attached to a mounting surface for mounting a mounting block to which a work is to be attached. In the pressure head in which the mounting block is detachable, the pad has a ring shape, and the center of the width of the pad substantially coincides with the center of each of the workpieces attached to the mounting block in a ring shape. It is characterized in that it is bonded to the mounting surface.

[Operation] The work adhered to the mounting block is pressed against the upper surface of the platen by a pressure head via a pad, and is polished by the rotating platen.

Here, even if the surface plate, the pressure head, and the mounting block are thermally deformed due to heat generated during processing, the pressing force from the pressure head is not only reliably transmitted to the mounting block via the pad, but also The small relative displacement between the members due to the thermal deformation is absorbed by the pad, and the work is pressed against the surface plate with a uniform force.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a body of a plane polishing apparatus,
In the body 10, a surface plate 11 is connected to a driving source (not shown) and is rotatably supported, and a plurality of pressure heads 12 are supported by an air cylinder 13 so as to be vertically movable. A mounting block 15 is removably attached to the lower surface of the mounting plate 15 via flexible pads 14, and a work 16 adhered to the lower surface of the mounting block 15 is pressed against the surface plate 11 by the pressing head 12. Is polished.

The pad 14 absorbs a small relative displacement between the members when the platen 11, the pressure head 12, the mounting block 15 and the like are thermally deformed due to heat generated during polishing, and the pressure from the pressure head 12 is applied. Is maintained so as to act uniformly on the work 16 and is made of a flexible material such as felt, polyurethane, and a plurality of O-rings. As shown in FIGS. 2 and 3, the pad 14 is formed in a ring shape, and is adhered to the lower surface of the pressure head 12 concentrically with the pressure head 12. At this time, in order to apply the pressing force of the pressure head 12 to each work 16 as uniformly as possible, as shown in FIG. It is desirable to bond the pads 14 in such a positional relationship as to be on the center 14a of the width 14.

In the planar polishing apparatus having the above configuration, the work 16 adhered to the mounting block 15 is
Is pressed against the upper surface of the surface plate 11 via the pad 14,
Polishing is performed by the rotating surface plate 11.

Here, the surface plate 11 and the pressure head 12,
Even when the temperature of the mounting block 15 and the like rises and they are thermally deformed, the pressing force from the pressure head 12 is not only reliably transmitted to the mounting block 15 via the pad 14, but also each Small relative displacement between members is absorbed by the pad 14, and the work 16
It will be pushed to 11. Therefore, the polishing accuracy is improved, and the polishing accuracy does not decrease due to the thermal deformation.

A water cooling jacket may be provided on both or one of the surface plate 11 and the pressurizing head 12, and polishing may be performed while supplying cooling water to the jacket. By using together, the effect of the present invention can be further enhanced.

 Next, an experimental example of the present invention will be described.

Using a planar polishing apparatus as shown in FIGS. 1 to 3,
A pressure test was performed on 100 workpieces each with and without the pad 14 attached to the pressure head 12, and variations in the thickness of each workpiece were measured. In this measurement, the thickness of the work was measured at five points indicated by crosses in FIG. 6 using a dial gauge or a thickness gauge, and the difference in thickness between the thinnest part and the thickest part was obtained. This difference is expressed as a thickness variation. The measurement results are shown in FIG. 4 (when a pad is used) and FIG. 5 (when a pad is not used).

The diameter of the pressure head and the mounting block used in this experiment were 18 inches, and the work was a 6-inch silicon wafer.

These experimental results show that the use of the pad maintains the flatness of the work and improves the processing accuracy.

[Effects of the Invention] As described above, according to the present invention, a flexible pad is adhered to the lower surface of the pressure head, and the mounting block is attached via the pad. The small relative displacement accompanying the thermal deformation of the mounting block or the like is absorbed by the pad, and the pressing force from the pressure head can be uniformly applied to the work.

Moreover, since it is only necessary to bond the flexible pad to the pressure head, the configuration, control, maintenance, management, and the like are remarkably simpler than in a case where the heat deformation is prevented by a water cooling method.

In addition, since the pad is formed in a ring shape and the center of the width thereof is made to substantially coincide with the center of each work adhered to the mounting block in a ring shape, a case where a plate-shaped pad is used Compared to the above, not only can the heat generated during processing be prevented from being transmitted to the pressure head due to its excellent heat insulation properties, but also the effect of uneven load due to thermal deformation and vibration of the mounting block due to its excellent buffering properties And effectively apply the pressure of the pressure head to the entire surface of the mounting block.Furthermore, the pressure from the pressure head is applied to each work located on the center of the pad width. There are advantages such as being able to work evenly.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part thereof, FIG. 3 is a bottom view of a pressure head, and FIGS. FIG. 6 is a bottom view of the work showing parallelism measurement points. 12… Pressure head, 14… Pad, 15… Mounting block, 16… Work.

Claims (1)

(57) [Claims] 1. A pressure head in which a flexible pad is adhered to a mounting surface for mounting a mounting block to which a workpiece is to be attached, and the mounting block is detachable via the pad. Wherein the center of the width of the pad and the center of each of the workpieces attached to the mounting block in a ring shape substantially adhere to the mounting surface. Pressure head for polishing equipment.