JPH0691523A - Work method for substrate - Google Patents

Abstract

PURPOSE:To reduce a difference in thickness of the work surface of a substrate by applying an adhesive on the surface reverse to the work surface of the substrate so that it has a desired thickness distribution, sticking it on a holding member under the thickness difference, and polishing the work surface, in the work of silicon wafers, etc. CONSTITUTION:When the surface reverse to the work surface of a substrate 5 is coated with an adhesive 5a, stuck on a substrate holding member 3, and polished by a rotary polishing surface plate 1, the adhesive is applied so that it may be distributed at a desired thickness, and the surface is stuck on the holding member 3 under the thickness difference distribution. Thus, because the adhesive is applied before polishing so that the thickness distribution may become that required for the work surface after the working has been completed, the flatness of the surface can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a substrate, and more particularly to a method of processing a substrate which can minimize the thickness difference distribution after polishing.

[0002]

2. Description of the Related Art Conventionally, as a means for fixing a substrate when processing a substrate such as a silicon wafer, an adhesion method using a spray method or a spin coating method is generally used. That is, as shown in FIG. 2, a polishing surface 1a on a rotary polishing platen 1 rotatably supported by a rotary shaft 2
A substrate holding member 3 which has a supporting surface 3a facing the polishing surface 1a and is rotatable by a rotating shaft 4 is disposed on the upper part of the substrate so as to be able to move up and down, and the substrate 5 is bonded to the bonding surface 5a with an adhesive. Is applied and adhered to the supporting surface 3a, or an adhesive is applied to the supporting surface 3a to adhere the adhering surface 5a of the substrate 5. At this time, in the case of the spray method, a predetermined spray is used to spray the substrate. On the other hand, in the case of the spin coating method, the adhesive is dropped on the support surface 3a or the adhesion surface 5a and then rotated and diffused by centrifugal force to reduce the adhesive thickness.

As an improved technique of these, for example, as disclosed in Japanese Examined Patent Publication No. 61-47665, an adhesive is horizontally held on a supporting surface and heated and condensed to lower its upper surface level. A precision processing method of adhering the substrate to the upper surface of the adhesive in the state has also been proposed.

[0004]

However, in any of the above-mentioned conventional bonding methods, the substrate 5 is bonded to the substrate holding member 3a having excellent flatness, the substrate anti-machined surface shape is corrected to a flat surface, and the machined surface is processed. This is a method of processing so as to be as close to the plane as possible, but there is a drawback that the error from the plane of the processed surface shape at the end of the processing directly becomes the substrate thickness difference.

For example, in the case of the mechanochemical polishing method which is often used for polishing a substrate at the present time, the edge portion of the substrate under a high processing pressure is better shaved and the surface shape becomes convex (for example, Toshiro Karaki). It is reported as "Wet mechanochemical polishing technology for Si wafers (machinery and tools, August 1984 issue, P.38-46)". Further, regarding the processing temperature distribution, a high temperature is well processed, for example, when the temperature of the central portion of the substrate is high, the central portion is well processed to have a concave shape (for example, Takao Nakamura et al. "Mirror finish of silicon wafer ( (2nd report) -Temperature distribution and flatness of polished surface of silicon wafer- (Refer to Japan Society for Precision Engineering, 56/6/1990, P.88-93) ”).

Normally, the substrate thickness distribution when the back surface of the processed surface of the substrate, that is, the non-processed surface, is planarly corrected, the distribution of the thickness of the substrate is It depends on the parallelism with the surface (more precisely, the parallelism of the regression surface of the machined surface when the non-machined surface is straightened to the anti-machined surface). It is extremely difficult to reduce the difference in substrate thickness due to the difference between the surface-corrected shape and the processed surface shape at the end of processing.

The present invention has been made in order to solve the problems of the conventional method as described above, and reduces the difference in substrate thickness caused by the difference between the processed surface shape at the end of processing and the non-processed surface corrected shape. An object of the present invention is to provide a method of processing a substrate that can be processed.

[0008]

SUMMARY OF THE INVENTION The present invention is a method for polishing a processed surface of a substrate held by a substrate holding member via an adhesive, in which a desired thickness difference of the adhesive is applied to the non-processed surface of the substrate. A method for processing a substrate is characterized in that the substrate is applied so as to have a distribution, and then the thickness difference distribution is held and adhered and fixed to the substrate holding member, and then the processed surface of the substrate is polished.

[0009]

[Operation] According to the present invention, the thickness distribution of the adhesive applied to the substrate holding member is applied in advance so that the thickness distribution required for the processed surface at the end of processing is applied, and then the substrate is unprocessed. Since the surfaces are bonded and processed, a substrate having a high flatness surface can be realized. That is, the adhesive should be applied in a convex shape if the processed surface has a convex shape, or in a concave shape if the processed surface has a concave shape. For example, it is possible to significantly reduce the difference in substrate thickness after processing.

Incidentally, the distribution of the difference in the substrate thickness after processing is reduced as the shape of the bonding surface of the adhesive is controlled in more detail. In addition, when the substrate is pressed against the substrate holding member to be bonded at the time of bonding, the thickness of the adhesive may change slightly depending on the type of the adhesive, but this must be regarded as an error. Therefore, if the degree of change in the thickness of the adhesive to be used is known from experience, it is possible to reduce the error by adjusting the adhesive during application.

[0011]

EXAMPLE After applying the present invention to a semiconductor silicon wafer, the parallelism on both sides of the semiconductor silicon wafer was set to 0 by a well-adjusted polishing machine.
It was processed to have a size of 3 μm or less. The polishing allowance at this time is about 20 μm. The results of the implementation at that time are shown in Figs. 1 (a) and 1 (b) together with the conventional method. That is, FIG. 1 (a)
Shows the difference in thickness (μm) after processing with respect to the difference in initial thickness (μm) before processing. Further, FIG. 1 (b) shows the difference in thickness (μm) after processing with respect to the flatness (μm) in the adhesive state at the end of processing, and the polishing allowance was 5
Processing pressure of 0.05kgf / cm ² to 1kg from μm to 40μm
It was obtained by changing the flatness after processing by changing to f / cm ² . As is clear from these figures, the variation in thickness difference according to the method of the present invention is smaller than that according to the conventional method.

Although the above embodiment has been described with respect to polishing, the present invention is not limited to this.
Other processing methods such as etching and grinding may be used.
Further, although the description has been given assuming that the adhesive is applied to the substrate, it is needless to say that similar effects can be obtained even when the adhesive is applied to the substrate holding member side.

[0013]

As described above, according to the present invention, the shape of the non-machined surface during machining is made closer to the machined surface, so that the distribution of the difference in thickness of the substrate after machining can be reduced.

[Brief description of drawings]

FIG. 1A is a characteristic diagram showing a post-processing thickness difference with respect to an initial thickness difference, and FIG. 1B is a characteristic diagram showing a post-processing thickness difference with respect to flatness in an adhesive state at the end of processing.

FIG. 2 is a side view showing an outline of a conventional polishing apparatus.

[Explanation of symbols]

 1 rotary polishing surface plate 2 rotary shaft 3 substrate holding member 4 rotary shaft 5 substrate

Claims (1)

[Claims] 1. A method for polishing a processed surface of a substrate held by a substrate holding member via an adhesive, wherein an adhesive is applied to a non-processed surface of the substrate so as to have a desired thickness difference distribution, Next, a method for processing a substrate, which comprises bonding and fixing the thickness difference distribution to the substrate holding member and then polishing the processed surface of the substrate.