JPH0569666B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wrapping device.

A wrapping device for semiconductor wafers is also disclosed in Japanese Patent Publication No. 14146/1983, and has the structure shown in FIG.

In this structure, a buff (abrasive cloth, therefore water-absorbing) is placed on the top surface of the rotating rotary polishing disk 1.
2 is attached. A plurality of wafers 3, which are objects to be wrapped, are held on the lower surface of a disc-shaped holder 4.

This holder 4 is fixed to the lower end of the support shaft 5. The support shaft 5 is attached to a support body 7 via a bearing 6. A load W is applied to the support body 7 by the weight 8.
Added. As a result, the lower surface (principal surface) of the wafer 3 is pressed against the rotary polishing disk 1 and is lapped (polished). The wafer 3 is circumferentially regulated by a ring-shaped retainer 10 and is in contact with the holder 4 via a pad 9. In addition, a vacuum hole 11 is provided in the holder part on the back side of the pad 9.
is perforated, and the wafer 3 is also held by vacuum.

Incidentally, in recent years, as wafers have become larger in diameter, requirements for processing accuracy (parallelism, etc.) have become very strict, and it has become impossible for the above-mentioned conventional apparatuses to meet these requirements. In this conventional apparatus, the sag in the peripheral portion of the wafer 3 is large. There are also problems such as large wafer thickness variations (TTV).

The main causes of these problems are (1) non-uniformity of the load coming from the polishing mechanism, and (2) variation in the moisture content within the wafer holding pad 9, which is thought to be the cause of the load applied to the wafer. This is thought to be caused by non-uniformity at the points.

The former problem has been solved by a method for which the present applicant has recently applied for a patent, but no good solution to the latter problem has been proposed yet. In other words, the load variation at each point within the wafer is caused by variation in the moisture content of the pad material, which has water absorption properties. To be more specific, the moisture content of the pad 9, which is considered to be uniform when the wafer 3 is held by the holder 4, becomes extremely low near the vacuum hole 11 due to the vacuum suction operation of the wafer 3. At the same time, experiments have shown that during polishing, a large amount of water (containing abrasive) is contained between the interface between pad 9 and wafer 3 and inside the pad, resulting in non-uniformity, as shown in Figure 2. Ta.

The present invention has been made to solve the above problem, and its purpose is to uniformize the distribution of the load applied from the holder to the wafer over the entire surface of the wafer, thereby reducing variations in the polishing margin due to variations in the load. However, it is an object of the present invention to provide a wrapping device that can provide wafers with good parallelism and no sag.

In order to achieve such an object, the wrapping device of the present invention has a holder facing the polishing disk surface hold the object to be polished through a water-absorbing pad, and a wrapping device is provided on the pad so as to penetrate through the holder. The object to be polished is attracted to the holding surface of the pad by the suction effect of the vacuum holes, and the ring-shaped retainer provided on the holder restricts the circumference of the object to be polished, and a load is applied to the holder. A lapping device for polishing a polished surface of an object to be polished while pressing it against a polishing disk surface, wherein the vacuum holes are opened in the circumferential direction near the periphery of the holding surface of the pad and inside the periphery. It is something.

The present invention will be explained below with reference to Examples.

FIG. 3 is a sectional view schematically showing a wrapping device according to an embodiment of the present invention. In the same figure, 1
2 is a buff (polishing cloth) glued to the top surface of the polishing disk; 3 is a semiconductor wafer to be polished; 4 is a rotating polishing disk whose top surface is the polishing surface; A disc-shaped holder, 5 a support shaft for supporting the holder, 6 a bearing for rotatably attaching the support shaft 5 to a support 7, 7 a support, and 8 a support 7
9 is a pad that holds the holder 4 and the wafer 3 in close contact with each other; 10 is a retainer that positions the wafer and prevents the wafer from coming out; 11 is a vacuum hole that complements the adhesion of the pad 9; be. Vacuum holes 11 are formed in the pad 9 so as to penetrate the holder 4, near the periphery of the semiconductor wafer holding surface of the pad 9, and inside thereof (i.e.
As in the past, two or more rows are provided in the circumferential direction at positions slightly closer to the periphery than between the center and the periphery of the semiconductor wafer holding surface.
This vacuum hole 11 supplements the adhesion of the pad 9 as described above, and its adsorption action allows it to suck in the polishing liquid that enters during polishing.

As described above, according to the wrapping apparatus of this embodiment, a plurality of vacuum holes 11 are provided in two rows in the circumferential direction in the vicinity of the periphery of the semiconductor wafer holding surface of the pad 9 and inside the periphery, so that the wrapping device can be easily polished. Most of the polishing liquid that enters from the outer circumferential side of the pad 9 is sucked into the vacuum hole 11 opened near the periphery of the semiconductor wafer holding surface, and what is not sucked in is opened inside. It will be sucked into the vacuum hole 11.

In other words, the vacuum hole 11 formed near the periphery of the pad 9 acts like a breakwater against the polishing liquid that enters the inside of the pad 9.

Therefore, if polishing is performed using such a wrapping device, the water content in the pad 9 will be small, and the pressure applied to the semiconductor wafer will be uniform. As a result, variations in the thickness of the wafer due to polishing are small, and the occurrence of sagging at the periphery of the wafer is also reduced, making it possible to perform high-quality wrapping.

Note that the present invention is not limited to the above embodiments.
That is, the vacuum holes may be formed using a porous material.

Furthermore, the present invention enables wrapping of objects other than semiconductor wafers with high precision and without any defects.

As described above, according to the wrapping device of the present invention, uniform wrapping is possible, and wrapping with high parallelism without sagging can be performed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a conventional wrapping device, FIG. 2 is a sectional view showing the state of pads in the conventional wrapping device, and FIG. 3 is a sectional view showing the main parts of a wrapping device according to an embodiment of the present invention. FIG. DESCRIPTION OF SYMBOLS 1...Rotary polisher, 2...Buff, 3...Wafer, 4...Holder, 5...Spindle, 6...Bearing, 7
...Support, 8...Weight, 9...Pad, 1
0...Retainer, 11...Vacuum hole.

Claims (1)

[Claims] 1. The object to be polished is held on a holder facing the surface of the polishing disk via a water-absorbing pad, and the object to be polished is held by the adsorption action of vacuum holes formed in the pad so as to penetrate through the holder. is attracted to the holding surface of the pad, the circumference of the object to be polished is regulated by a ring-shaped retainer provided on the holder, and the object to be polished is fixed by applying a load to the holder. A lapping device for polishing a polishing surface while pressing it against the surface of the polishing disk, characterized in that the vacuum holes are opened in the circumferential direction near the periphery of the holding surface of the pad and inside the same. Wrapping device.