A chemical polishing fixture

Abstract

The present invention discloses a chemical polishing fixture. The fixture is integrally cylindrical, and a rectangular groove, a reserved wafer-taking port, an annular groove and a rod-shaped groove are arranged on the circular surface at the top of the cylinder. The rectangular groove is arranged in the central area of the circular surface at the top, is rectangular, and is used for placing the wafer or thin film to be polished. A reserved wafer-taking port communicated with it is respectively arranged at each of the four corners of the rectangular groove. At least one closed-loop annular groove is arranged in a concentric and radial manner in the edge interval between the rectangular groove and the circular surface at the top. At least one rod-shaped groove is arranged radially at a position pointing from the edge of the circular surface at the top to the center of the rectangular groove, and its length can cover the four annular grooves. The present invention can ensure the polishing uniformity of the surface of the polishing material, and is convenient for removing and cleaning the material, with simple operation. At the same time, it can solve the problem of the adverse effect on the substrate surface caused by the pollution introduced by wax in traditional chemical polishing.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor material epitaxy, and relates to a chemical polishing fixture and its use, and particularly relates to a chemical polishing fixture for realizing chemical polishing of cadmium zinc telluride substrate wafers or mercury cadmium telluride thin films. Background Art

[0002] In the process of preparing mercury cadmium telluride infrared focal plane detectors, the surface quality of cadmium zinc telluride substrates and mercury cadmium telluride thin films is the basis for developing long-wave infrared focal plane detectors. To meet the development requirements of infrared focal plane devices, improving the surface processing level of cadmium zinc telluride substrates and mercury cadmium telluride thin films is an important direction for the development of detector materials.

[0003] The chemical polishing process is the last step in processing cadmium zinc telluride substrates / mercury cadmium telluride thin films. It uses the corrosiveness of chemical solutions to remove the damage caused by mechanical polishing, so as to obtain a bright, flat, and damage-free surface of cadmium zinc telluride substrates and mercury cadmium telluride thin films. The process level of chemical polishing directly affects the performance of the detector.

[0004] Traditional chemical polishing requires bonding the object to be polished, "cadmium zinc telluride substrate / mercury cadmium telluride thin film", to a glass substrate with wax, and then buckling the glass disk on a handle and manually inverting it onto a polishing pad for chemical polishing. In this method, during the polishing process, wax contamination will be introduced, affecting the surface quality of the liquid phase epitaxial thin film and the device performance. At the same time, both the glass substrate and the wafer are planar structures without a drainage device. If the polishing liquid that has not participated in the chemical reaction does not leave the material surface in time, the polishing liquid is likely to accumulate in the edge area of the material, causing over-corrosion of the material in this area and affecting the surface polishing uniformity of the cadmium zinc telluride substrate / mercury cadmium telluride thin film. Summary of the Invention

[0005] In order to solve the problems existing in the traditional chemical polishing process, such as the introduction of wax contamination and uneven polishing, the present invention provides a chemical polishing fixture and its use.

[0006] The chemical polishing fixture of the present invention is generally cylindrical, and a rectangular groove, a reserved wafer-taking opening, an annular groove, and a rod-shaped groove are provided on the circular surface at the top of the cylinder; the rectangular groove is arranged in the central area of the circular surface at the top, in a rectangular shape, for placing the wafer or thin film to be polished. The planar size of the rectangular groove is slightly larger than the planar size of the wafer or thin film to be polished, and the depression depth of the rectangular groove is slightly smaller than the thickness of the wafer or thin film; a reserved wafer-taking opening communicating therewith is respectively arranged at the four corners of the rectangular groove, for enabling a wafer-taking tool (such as tweezers) to push out the wafer or thin film to be polished from the lower part through the reserved wafer-taking opening. The depth of the reserved wafer-taking opening is slightly deeper than the depth of the rectangular groove to prevent the four corners of the wafer or thin film to be polished from colliding with the optical polishing fixture and chipping, and at the same time it is also convenient for subsequent wafer-taking; at least one closed-loop annular groove is arranged in a concentric and radial manner in the edge interval between the rectangular groove and the circular surface at the top, and the depth of the annular groove is the same as the depth of the rectangular groove; at least one rod-shaped groove is arranged radially from the edge of the circular surface at the top to the center of the rectangular groove, and its length can cover the four annular grooves, and its depth is the same as that of the annular groove; the rectangular groove and the rod-shaped groove can play roles such as facilitating the flow of the chemical polishing liquid during the polishing process, making it evenly distributed on the surface of the wafer or thin film to be polished, so as to achieve a good and uniform polishing effect, etc.

[0007] Preferably, the material of the chemical polishing fixture is polytetrafluoroethylene.

[0008] By means of the technical solution of the present invention, problems such as the adverse effects caused by wax-introduced pollution on the surface of the substrate and thin film in traditional chemical polishing, uneven polishing, edge chipping, and wafer dropping can be solved.

[0009] The working principle of the present invention:

[0010] When the chemical polishing fixture of the present invention performs surface polishing on the polishing material, first drop 2 drops of methanol into the rectangular groove, place the substrate / thin film to be polished in the rectangular groove, gently push the wafer or thin film to be polished to make it evenly contact with the surface of the rectangular groove, and use the van der Waals force of the liquid to adsorb the substrate / thin film in the rectangular groove so that it will not fall off. Then place the fixture on the polishing pad of the chemical polishing machine to perform circular motion and swinging motion. The annular grooves on the surface of the fixture enable the polishing liquid to have better fluidity during chemical polishing. The excess polishing liquid leaves the material surface in time through the annular groove and the rod-shaped groove, avoiding over-corrosion phenomenon and ensuring polishing uniformity. The design of the reserved openings at the four corners of the fixture facilitates the wafer-taking tool to overcome the van der Waals force between the water and the substrate / thin film and easily take the wafer, solving problems such as edge chipping, cracking, and wafer dropping during the wafer-taking process, and at the same time also avoiding damage to the material surface caused by chipping due to impact during the polishing process.

[0011] The beneficial effects of the present invention:

[0012] By means of the chemical polishing fixture provided by the present invention, four problems existing in the traditional chemical polishing process are solved. When using this fixture for chemical polishing, the wafer or thin film to be polished is adsorbed on the fixture by the van der Waals force of the liquid, realizing a wax-free process and avoiding wax pollution; the introduction of the drainage groove avoids the over-corrosion phenomenon caused by the accumulation of chemical polishing liquid on the material surface; the circular design at the four corners avoids the hard contact between the material corners and the fixture, solving the problems of edge chipping and cracking; the design of the wafer-taking reserved wafer-taking opening makes the wafer-loading and wafer-taking in the chemical polishing process fast and convenient, improving production efficiency. Description of the Drawings

[0013] Figure 1 It is a top view of the chemical polishing fixture according to an embodiment of the present invention.

[0014] Wherein: 1 - chemical polishing fixture; 2 - rectangular groove; 3 - reserved wafer-taking opening; 4 - annular groove; 5 - rod-shaped groove. Detailed Embodiments

[0015] In order to solve the four problems existing in the traditional chemical polishing process, the present invention provides a chemical polishing fixture. The following further details the present invention in conjunction with the drawings and embodiments.

[0016] According to an embodiment of the present invention, a chemical polishing fixture is provided, as Figure 1 shown, including a rectangular groove 2, a reserved wafer-taking opening 3, an annular groove 4, and a rod-shaped groove 5. The following details each part:

[0017] A coaxial rectangular groove 2 is provided at the center of the fixture 1 for placing the wafer or thin film to be chemically polished;

[0018] Circular reserved wafer-taking openings 3 communicating therewith are respectively provided at the four corners of the rectangular groove 2 to prevent chipping of the four corners of the wafer or thin film to be polished when colliding with the fixture and facilitate subsequent wafer-taking; four annular grooves 4 are provided in the middle of the rectangular groove 2 of the fixture 1 from the rectangular groove 2 to the edge position, which is conducive to the flow of the chemical polishing liquid during the polishing process, enabling it to be evenly distributed on the surface of the wafer or thin film to be polished, achieving a good and uniform polishing effect; four rod-shaped grooves are provided in the direction from the edge of the fixture 1 to the midpoints of the four sides of the central rectangle. These four rod-shaped grooves form a 90° angle with each other, which is conducive to the circulating flow of the polishing liquid.

[0019] Specifically, the planar dimension of the central rectangular groove 2 of the fixture 1 is slightly larger than the planar dimension of the wafer or thin film to be polished. The planar dimension of the rectangular groove is designed and modified according to the size requirements of the wafer or thin film to be polished. The depth of the rectangular groove 2 is slightly less than the thickness of the wafer or thin film to be polished, so as to form a certain pressure on the surface of the wafer or thin film to be polished and achieve a better polishing effect under a slight pressure.

[0020] Specifically, reserved wafer-taking openings 3 are respectively arranged at four corners of the rectangular groove 2, for enabling a wafer-taking tool (such as tweezers) to push out a wafer or a thin film to be polished from the lower part through the reserved wafer-taking openings. The depth of the reserved wafer-taking openings 3 is slightly deeper than the depth of the rectangular groove.

[0021] Specifically, the depths of the annular groove 4 and the rod-shaped groove 5 provided on the fixture 1 are the same as that of the rectangular groove 2.

[0022] Specifically, the material of the fixture 1 is polytetrafluoroethylene. Using polytetrafluoroethylene as the processing material, while having high physical stability and chemical stability such as corrosion resistance, it also has good mechanical strength and plasticity.

[0023] For a chemical polishing fixture provided by the present invention, 1-2 ml of methanol solution is dropped into the central rectangular groove with a dropper, and a cadmium zinc telluride substrate / cadmium mercury telluride thin film is gently placed in the rectangular groove, and the fixture is slightly shaken to make the methanol evenly distributed at the bottom of the wafer or thin film to be polished. It is adsorbed on the fixture by the van der Waals force of the liquid, which can avoid the pollution of wax in the traditional chemical polishing process and effectively improve the problem of uneven polishing on the surface of the material. The wafer or thin film to be polished is placed in the rectangular groove, and the reserved wafer-taking openings at the four corners facilitate the insertion of tweezers to conveniently remove the wafer or thin film after chemical polishing. At the same time, the four corners that are easily damaged during the polishing process are protected, effectively avoiding damage to the surface of the substrate / thin film caused by chipping due to impact. The purpose of setting the four annular grooves and the four rod-shaped grooves is to enable the liquid to have better fluidity during chemical polishing when the fixture rotates. Since during the polishing process, the fixture with the wafer or thin film to be polished makes a circular motion on the polishing pad, and the polishing liquid flows out towards the outside of the fixture under the action of centrifugal force, the annular grooves and the rod-shaped grooves provide a smooth outflow channel for it, ensuring that the chemical polishing liquid can evenly contact the surface of the wafer or thin film to be polished during chemical polishing, and avoiding the over-corrosion phenomenon caused by the residual of excess chemical polishing liquid.

[0024] The above are only embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A chemical polishing fixture, characterized in that: The chemical polishing fixture is integrally cylindrical, and a rectangular groove, a reserved wafer-taking opening, an annular groove and a rod-shaped groove are arranged on the circular surface at the top of the cylinder; The rectangular groove is arranged in the central area of the circular surface at the top for placing the wafer or thin film to be polished; A reserved wafer-taking opening communicating therewith is respectively arranged at the four corners of the rectangular groove; Four closed-loop annular grooves are arranged in a concentric and radial manner in the edge interval between the rectangular groove and the circular surface at the top; Four rod-shaped grooves are arranged radially at the midpoints of the four sides of the rectangle pointing from the edge of the circular surface at the top to the center of the rectangular groove. The four rod-shaped grooves are at an angle of 90° to each other, and their lengths can cover the three outer annular grooves; The depths of the reserved wafer-taking opening, the annular groove, the rectangular groove and the rod-shaped groove are the same; The material of the chemical polishing fixture is polytetrafluoroethylene.

2. The chemical polishing fixture according to claim 1, characterized in that: The planar dimension of the rectangular groove is slightly larger than the planar dimension of the wafer or thin film to be polished, and its recessed depth is slightly smaller than the thickness of the wafer or thin film.

3. The chemical polishing fixture according to claim 1, characterized in that: The reserved wafer-taking opening is circular.

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