CN113211337B

CN113211337B - Preparation method of polishing disk for polishing superhard substrate sheet and precision polishing method

Info

Publication number: CN113211337B
Application number: CN202110538166.9A
Authority: CN
Inventors: 李祥彪; 仲崇贵
Original assignee: Nantong University
Current assignee: Nantong University
Priority date: 2021-05-18
Filing date: 2021-05-18
Publication date: 2023-04-07
Anticipated expiration: 2041-05-18
Also published as: CN113211337A

Abstract

The invention relates to a preparation method of a polishing disk for polishing a superhard substrate sheet and a precision polishing method, belonging to the substrate processing technology. The invention provides a preparation method of a novel polishing disk for polishing a substrate, which is characterized in that a multi-layer composite polishing disk is used for precisely polishing the substrate, compared with the traditional substrate polishing process, the process flow is greatly simplified, the substrate polishing disk with a better surface type is obtained, the polished substrate has small average thickness difference and low bending warpage. The method has simple process and easy operation.

Description

Preparation method of polishing disk for polishing superhard substrate sheet and precision polishing method

Technical Field

The invention relates to the technical field of substrate polishing, in particular to a preparation method and a precise polishing method of a polishing disk for polishing a superhard substrate sheet.

Background

The substrate slice is an important basic material in the semiconductor industry, and the general preparation process comprises the steps of growing a crystal by a gas phase or liquid phase method, then carrying out processes such as cutting, grinding, polishing, chemical mechanical polishing and the like on the crystal, and cleaning and packaging to obtain the box-opening ready-to-use substrate slice for epitaxy. The requirements of the epitaxial process of the substrate slice on the substrate slice include no damage and no scratch on the surface, smaller thickness difference, smaller bending warpage and better surface flatness.

The two parts of the growth technique of the crystal and the cutting and processing technique of the substrate sheet, which is the guarantee and basis of the production of electronic components, are indispensable for the final shaping and use of the substrate sheet. To perfectly achieve the excellent properties of the substrate material, the wafer is required to be very smooth and flat, have no defects on the surface, and have no damage on the sub-surface. Such requirements can only be fulfilled with the support of advanced processes and efficient processing techniques, which are therefore of central importance for the application of the substrate sheet.

Due to the increasing demands on the application of substrate sheets, the increasing demands on their use, and the decreasing manufacturing costs, conventional mechanical lapping and polishing techniques have been an obstacle to the widespread use of superhard substrate materials, represented by silicon carbide gallium nitride. Can not adapt to and meet the production requirements of modern semiconductor components, and limits the development of the third generation semiconductor industry to a certain extent.

In the conventional processing process of the substrate material, long-time grinding and polishing are needed, which inevitably brings processing stress to the substrate sheet, so that the surface shape of the substrate sheet is deteriorated, and the bending warp degree is increased. Particularly, the chemical mechanical polishing process is a long chemical mechanical polishing process in the later period, and the chemical mechanical polishing process has the function of removing surface damage caused by the mechanical polishing process and obtaining surface roughness of an atomic level. However, the time of the general chemical mechanical polishing process is longer than 4 hours, which greatly increases the processing stress in the substrate, so that the surface type is poor and the epitaxial process requirements are difficult to meet. This is particularly the case for large size substrate sheets. As is well known, the integration of integrated circuit components has grown exponentially according to moore's law, and the pursuit of lower cost requires the fabrication of larger sized substrate pieces. The long polishing process not only reduces the rate of good product of the substrate piece, but also increases the cost of the product.

In the traditional processing technology, the grinding, the fine grinding and the polishing of the substrate sheet are all discrete procedures, and the integration level is low. And the mixing action of the substrate slice, the grinding disc and the grinding material is performed in each process. Not only is time and labor consuming, but also the cost is increased, and the processing quality of the processed substrate slice is difficult to control and guarantee.

Disclosure of Invention

In order to solve the problems, the invention provides a polishing disk preparation method and a precision polishing method for polishing a superhard substrate sheet.

In order to solve the technical problems, the invention adopts the technical scheme that:

the preparation method of the polishing disk for polishing the superhard substrate slice comprises the following steps:

step 1, preparing a polishing disc blank;

step 1.1, selecting grinding materials with the first particle size, auxiliary grinding powder with the same particle size and bonding materials, fully mixing the grinding materials with the first particle size and the auxiliary grinding powder with the same particle size, injecting the mixture into a mold, and carrying out pressure molding on the mixed powder to form a first layer of polishing disk blank.

And step 1.2, selecting the grinding material with the second particle size, the auxiliary grinding powder with the same particle size and the bonding material, fully mixing, injecting into the same mold, and carrying out pressure forming on the mixed powder again to form a second layer polishing disk blank.

And step 1.3, selecting grinding materials with a third particle size, auxiliary grinding powder with the same particle size and bonding materials, fully mixing, injecting the mixture into the same mold, and carrying out pressure forming on the mixed powder again to form a third layer of polishing disk blank.

Step 1.4, sequentially stacking a first layer of polishing disk blank, a second layer of polishing disk blank and a third layer of polishing disk blank to form a three-layer composite polishing disk blank;

step 2, pressurizing and molding the composite polishing disk blank processed in the step 1 again, and sintering at high temperature to obtain a composite polishing disk;

and 3, fixing the composite polishing disc processed in the step 2 on a grinding support.

Further, the first particle size is smaller than the size of the second particle size, and the second particle size is smaller than the size of the third particle size. Specifically, the first particle size is 1 micron, the second particle size is 3 microns, and the third particle size is 6 microns.

Further, step 1 further comprises: and 1.5, repeating the steps 1.1-1.4 to obtain the multiple three-layer composite polishing disk blank.

Further, the auxiliary grinding powder includes, but is not limited to, one or more of aluminum oxide, silicon carbide, boron carbide, and silicon dioxide.

Further, the abrasive is sixty percent by volume of diamond, the auxiliary abrasive powder is ten percent by volume of alumina, the particle size of the alumina in the same layer is the same as that of the diamond, and the bonding material is a polyester material.

Further, the thicknesses of the third layer of grinding disc blank, the second layer of grinding disc blank and the first layer of grinding disc polishing disc are respectively 100 microns, 50 microns and 30 microns.

A method of precision polishing a superhard substrate wafer comprising the steps of:

step 1, selecting composite polishing disks with different diameters according to the material quality, the removal amount and the surface processing quality of a polished substrate sheet, and replacing a conventional metal or polyester grinding disk with the composite polishing disk on general polishing equipment;

step 2, polishing the substrate slice, wherein only pure water is continuously sprayed without spraying polishing liquid in the whole polishing process;

and 3, taking down the substrate sheet to finish one-time polishing after the set polishing time is finished.

The invention has the following beneficial effects:

the invention provides a method for preparing a polishing disk for polishing a superhard substrate and a precision polishing method. The method has simple process and easy operation. Not only greatly reduces the mechanical polishing time of the substrate, but also saves the cost.

Drawings

FIG. 1 is a flow chart of the operation of the present invention.

FIG. 2 is a schematic view of a composite polishing pad:

FIG. 3 is a white light interferometer test result of a sample polished according to an embodiment of the present invention.

Wherein, 1, diamonds with different grain diameters, 2, alumina with different grain diameters, and 3, silicon dioxide with different grain diameters.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to specific examples. The following examples are illustrative only and are not to be construed as limiting the invention.

In view of the above difficulties in the prior art, the present invention provides a method for manufacturing a polishing disk for polishing a superhard substrate sheet, as shown in fig. 1, by using a multi-layer composite polishing disk to precisely polish a substrate sheet, which greatly simplifies the process flow compared with the conventional substrate sheet polishing process, and obtains a substrate polishing sheet with a better surface type, wherein the polished substrate sheet has a small average thickness difference and a low bending warpage.

The three-inch superhard silicon carbide substrate slice is subjected to precision mechanical polishing by adopting the three-layer composite polishing disk, the abrasive of the three-layer polishing disk is formed by mixing, ball-milling and sintering polyester materials, wherein the abrasive comprises sixty percent of diamond with the volume ratio of 1 micrometer, 3 micrometer and 6 micrometer and ten percent of alumina with the same particle size, and the thicknesses of the three-layer polishing disk from large to small are respectively 100 micrometers, 50 micrometers and 30 micrometers. And the polished silicon carbide substrate with a better surface type is obtained, and the polished substrate has small average thickness difference and low bending warpage.

As shown in FIG. 2, the abrasive in the three-layer polishing disk adopts diamonds 1 with different grain sizes, the auxiliary abrasive adopts alumina 2 with different grain sizes and silica 3 with different grain sizes, and the grain sizes of the diamonds, the alumina and the silica in the same layer are the same.

The obtained three-inch silicon carbide substrate wafer has a good surface type detected by a white light interferometer, the surface roughness Ra is 1.46nm, and the Rq is 1.89nm.

Therefore, the invention provides a novel method for preparing the polishing disk for polishing the substrate slice, the substrate slice is precisely polished by using the multi-layer composite polishing disk, compared with the traditional substrate slice polishing process, the process flow is greatly simplified, and the substrate polishing slice with a better surface type is obtained, as shown in figure 3, the polished substrate slice has small average thickness difference and low bending warpage.

In the description herein, references to "an embodiment," "a specific embodiment," "some embodiments," or the like, mean that a particular feature, material, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment. Furthermore, the particular features, materials, structures, or characteristics described may be combined in any suitable manner in any one or more embodiments.

While embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. The preparation method of the polishing disk for polishing the superhard substrate slice is characterized by comprising the following steps:

step 1, preparing a polishing disc blank;

step 1.1, selecting grinding materials with a first particle size, auxiliary grinding powder with the same particle size and a bonding material, fully mixing the grinding materials with the first particle size and the auxiliary grinding powder with the same particle size, injecting the mixture into a mold, and performing pressure forming on the mixed powder to form a first layer of polishing disc blank;

step 1.2, selecting abrasive materials with a second particle size, auxiliary grinding powder with the same particle size and bonding materials, fully mixing the abrasive materials and the auxiliary grinding powder with the same particle size, injecting the mixture into the same mold, and carrying out pressure forming on the mixed powder again to form a second layer of polishing disk blank;

step 1.3, selecting grinding materials with a third particle size, auxiliary grinding powder with the same particle size and bonding materials, fully mixing, injecting the mixture into the same mold, and carrying out pressure forming on the mixed powder again to form a third layer of polishing disk blank;

step 3, fixing the composite polishing disc processed in the step 2 on a grinding support;

in the above steps, the abrasive is sixty volume percent of diamond, the auxiliary abrasive powder is ten volume percent of alumina, the particle size of alumina in the same layer is the same as that of diamond, and the bonding material is a polyester material.

2. The method of manufacturing a polishing pad for polishing a superhard substrate sheet according to claim 1, wherein the first grain size is smaller than the second grain size, and the second grain size is smaller than the third grain size.

3. The method of manufacturing a polishing pad for polishing a superhard substrate wafer as claimed in claim 1, wherein the step 1 further comprises: and 1.5, repeating the steps 1.1-1.4 to obtain the multiple three-layer composite polishing disk blank.

4. A superhard substrate sheet precision polishing method, wherein the polishing method is based on a method of manufacturing a polishing pad for polishing a superhard substrate sheet as claimed in claim 1, the polishing method comprising the steps of:

step 1, selecting composite polishing disks with different diameters according to the material quality, the removal amount and the surface processing quality of a polished substrate slice, and replacing a conventional metal or polyester grinding disk with the composite polishing disk on general polishing equipment;

and 3, taking down the substrate piece after the set polishing time is finished, and finishing one-time polishing.