JPS6317589B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a precision processing method for ultra-thin parts with a thickness of 100 μm or less, and is capable of obtaining adhesive strength and adhesive accuracy for a long time without using wax at all. Moreover, since no waxes are used at all, it is possible to reduce the burden of processes such as melting and heating removal of wax and post-washing, so that the function can be fully satisfied. In the conventional single-sided wrapping and polishing method, the fixing strength is maintained by interposing wax between the base substrate and the workpiece (workpiece), but if there is a large amount of wax, the fixing force can be maintained. This causes variations in the thickness of the wax layer, and if the amount of wax is extremely reduced, the fixing force is weakened. In addition, there is a limit to the selection of waxes because if the melting point is too high, workability will be poor, and there is also a restriction on spreading the wax thinly.In general, waxes with a low melting point mainly composed of paraffin etc. are used at the expense of strength. The reality is that
Furthermore, it is difficult to completely eliminate impurities when refining wax, and due to the non-uniformity of the wax layer and the non-uniformity of the thermal stress distribution between the workpiece and the wax, it is difficult to uniformize the wax layer with high precision. It was very difficult.

As the size of the workpiece increases, especially when mass production is taken into account, variations in the wax layer of 3 to 5 μm inevitably occur, and this was considered to be the limit. As described above, when there is variation in the wax layer, the wrapping and polishing thickness accuracy of the workpiece is linearly affected by the variation, and the thickness accuracy of the workpiece becomes extremely poor.

One way to eliminate the negative effects of using wax is to use vacuum vacuum adsorption without using wax at all, but especially when it comes to thin objects, the stress may be uneven between the adsorbed and non-adsorbed parts. This generally results in a suction pattern on the polished surface, resulting in extremely poor flatness.

Furthermore, as another method, a substrate that is not usually a sintered body,
For example, a method of temporary adhesion by applying water on a glass substrate or a metal substrate has been considered for some time, but in this case, the adhesive strength varies depending on the amount of water interposed between the workpiece and the substrate. Moreover, as time passes, moisture evaporates, resulting in a bond close to optical bonding, but the adhesive strength deteriorates.

The object of the present invention is to propose a processing method that can eliminate these problems, completely eliminate the influence of the adhesive layer, and obtain sufficient adhesive strength.

In order to achieve the above objective, the substrate for adhering the workpiece is made of a sintered body with high porosity, water adhesion is adopted for adhering the workpiece, and water is impregnated inside the pores of the substrate. By keeping the amount of interposition between the workpiece and the substrate almost constant, and at the same time applying oil sealing around the workpiece, it is possible to maintain adhesive strength over a long period of time without decreasing the strength due to water evaporation.

A sintered body with high porosity is used as the substrate used in the present invention, and the sintered body is a mixture of raw material powder mainly composed of Al ₂ O ₃ or SiC or WC and metal powder and a binder such as Co or Ni. Filled and in an electro-reducing atmosphere
A porous substrate is formed by heating and sintering at 850°C to 1500°C.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing the state of adhesion between a thin wafer and a substrate according to an embodiment of the present invention, and FIG. 2 is a partially detailed view thereof.

1 is a workpiece, 2 is a substrate, 3 is water, and 4 is sealing oil.

First, the bonding surface of the substrate 2 is previously mirror-finished for 0.1 seconds or less, and water 3 is impregnated into the substrate before bonding. Since the inside has a porous composition, when water is added, the water penetrates into the inside due to capillary action. At least the adhesive surface of the workpiece 1 is mirror-finished, and the bonding surface with the substrate 2 is filled with water. If there is too much moisture on the surface of the substrate 2, the adhesive strength will be poor, so the moisture on the surface of the substrate 2 is evaporated by forced drying or natural drying over time, and the work 1 is bonded with the moisture in the porous areas. This increases the bond strength. Once the bonding strength has increased to a certain extent, the outer periphery can be sealed with low viscosity silicone oil 4, etc. to prevent moisture from evaporating between the workpiece 1 and the substrate 2, so that the bonding strength can be maintained sufficiently. Fixation of the workpiece can be achieved. In the case of silicone oil 4, it is effective in terms of high temperature chemical resistance. By using the sealing oil 4 in combination, the surface tension can be maintained due to the moisture impregnated inside the substrate even after a long period of time, and the adhesive strength can be maintained.

As described above, according to the present invention, by water-bonding a porous substrate, it is possible to eliminate the adverse effects of the adhesive and to achieve uniform thickness accuracy of the workpiece, and further, by sealing with oil, it is possible to bond the workpiece with water. Since the strength can be maintained, extremely high precision processing can be achieved especially when wrapping and polishing ultra-thin wafers of 100 μm or less.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the bonding between the thin wafer and the substrate.
FIG. 2 is a detailed view of a portion thereof. 1...Workpiece, 2...Substrate, 3...Water, 4...Sealing oil.

Claims (1)

[Claims] 1. In ultra-precision one-sided wrapping or polishing of ultra-thin parts with a thickness of approximately 100 μm or less made of crystal, glass, ceramic, silicon, ferrite, etc., porous Al ₂ O ₃ is used as a substrate to bond the workpiece. The workpiece is bonded to the substrate using a sintered body of SiC, SiC, WC, metal, etc., the bonding surface of which has been mirror-finished in advance, using the surface tension of water, and the workpiece is sealed with an oil film or the like. A part processing method characterized by performing processing such as wrapping or polishing after fixing the part to the substrate.