Chemical mechanical composite processing method for silicon carbide surface

Abstract

First, a grinding / polishing tool (1) containing a composite active metal and abrasive grains, and silicon carbide (2) are attached to the machine base of a grinding / polishing device, respectively, and then the silicon carbide (2) is pressed against the surface of the grinding / polishing tool (1) by the action of an external force. Finally, the grinding / polishing tool (1) rotating at high speed and the silicon carbide (2) are caused to move relative to each other, generating high-speed friction and inducing a chemical reaction between the active metal and silicon carbide (2). Furthermore, the reaction layer is removed by the mechanical action between the abrasive grains and silicon carbide (2), thereby forming a processing form of a chemical-mechanical composite cycle, and this is a method for chemical mechanical composite machining of silicon carbide surfaces, which realizes grinding and polishing of the surface of the silicon carbide (2).

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-precision machining, and particularly to a chemical mechanical composite machining method for the surface of silicon carbide.

Background Art

[0002] As a third-generation semiconductor material, silicon carbide (SiC) has excellent physical properties such as a wide bandgap, high thermal conductivity, good thermal stability, and high saturation drift velocity, and is widely applied in fields such as high frequency, high temperature, radiation, and optoelectronics. The industrial application of silicon carbide has very high requirements for its surface quality. At the same time, due to the very high hardness and chemical inertness of silicon carbide, it is difficult to process, and these characteristics hinder its wide application in the industrial field.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Currently, the processing steps of single-crystalline SiC mainly include wire saw cutting, grinding, and chemical mechanical polishing. Chemical mechanical polishing is the last step in silicon carbide processing. Under the action of appropriate pressure, polishing liquid is added, and the surface of the silicon carbide wafer is polished by a polishing pad. However, the polishing liquid during processing is easy to pollute the environment. At the same time, there are problems such as low removal rate, requiring many steps and a large amount of processing time.

[0005] Patent Document 1 (Patent Publication No. CN101966689B) discloses a method for surface polishing the carbon surface of a large-diameter 4H-SiC wafer. The acidic polishing liquid provided in this patent improves the surface polishing effect of a single-crystal wafer, but there are problems such as low polishing efficiency, too long polishing time, and easy contamination of the polishing liquid.

[0006] Patent Document 2 (Patent Publication No. CN109702639B) discloses a method for polishing a SiC single-crystal wafer. This patent grinds and polishes a SiC single-crystal wafer using an aqueous grinding liquid and a polishing liquid, but there are still problems such as low removal efficiency and long processing time, and the grinding liquid and polishing liquid used are also easy to pollute the environment.

[0007] Patent Document 3 (Patent Publication No. CN108949036B) discloses a method for polishing a silicon carbide crystal. This patent has improved the polishing speed and effect to a certain extent, but the improvement effect is limited. There are still problems such as low polishing efficiency, too long polishing time, and easy contamination of the polishing liquid.

[0008] An object of the present invention is to provide a chemical mechanical composite processing method for the silicon carbide surface that solves the conventional problems such as low processing efficiency of silicon carbide, large damage to the silicon carbide surface and subsurface, and environmental pollution of the polishing liquid.

Means for Solving the Problems

[0009] To achieve the above object, the solution of the present invention is as follows: First, a grinding and polishing tool containing a composite active metal and abrasive grains and silicon carbide are respectively attached to the machine base of a grinding and polishing device. Then, under the action of an external force, silicon carbide is pressed against the surface of the grinding and polishing tool. Finally, the grinding and polishing tool rotating at high speed and silicon carbide are relatively moved to generate high-speed friction, thereby forming a chemical-mechanical composite cycle processing mode to realize the grinding and polishing of the surface of silicon carbide. This step includes the process of the chemical-mechanical composite cycle, in which the active metal on the grinding and polishing tool and the surface of silicon carbide undergo a chemical reaction due to friction induction to generate a chemical reaction layer. Then, the chemical reaction layer is scraped off by the mechanical action of the abrasive grains to expose a new surface of silicon carbide, causing a chemical reaction again to generate a chemical reaction layer, which is then mechanically scraped off again by the abrasive grains. By such a cycle action, it is a chemical-mechanical composite processing method for the surface of silicon carbide to form the processing mode of the chemical-mechanical composite cycle.

[0010] The grinding and polishing tool is formed by hot pressing and sintering an active metal and abrasive grains at a volume ratio of 7:1 to 1:1.

[0011] The active metal is a metal that reacts chemically with the C plane of silicon carbide or the Si plane of silicon carbide.

[0012] The active metal that reacts chemically with the C plane of silicon carbide includes one or more of iron, cobalt, nickel, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tungsten, aluminum, and niobium. The generated chemical reaction layer includes at least one of metal silicide, metal carbide, Si, and C.

[0013] The active metal that reacts chemically with the Si plane of silicon carbide includes one or more of cobalt, nickel, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tungsten, aluminum, and niobium. The generated chemical reaction layer includes at least one of metal silicide, metal carbide, Si, and C.

[0014] The active metal is one or a combination of a plurality of metal simple substances and metal alloys.

[0015] The abrasive grains include one or a combination of a plurality of aluminum oxide, cubic boron nitride, diamond, silicon nitride, and silicon carbide.

[0016] The high-speed friction is dry friction or wet friction. The gas atmosphere of the high-speed friction is at least one of an air atmosphere, a lean atmosphere, and an inert gas atmosphere. The temperature of the high-speed friction is room temperature or high temperature. The speed of the high-speed friction is 1 to 50 m / s. The pressure of the high-speed friction is 0.1 to 1 Mpa.

[0017] The grinding and polishing equipment includes a high-speed surface plate whose spindle is driven to rotate by a rotation mechanism, and a linear motion stage that is driven to move up and down by a transmission mechanism. The grinding and polishing tool is attached to the spindle of the high-speed surface plate, and the silicon carbide is attached to the jig of the linear motion stage.

[0018] The chemical mechanical composite processing method for the surface of silicon carbide according to the present invention adopts a method of removing silicon carbide by combining a metal friction-induced chemical reaction and a mechanical scraping action. The active metal chemically reacts with silicon carbide under the conditions of high-speed friction to generate a soft chemical reaction layer (such as metal silicide, metal carbide, Si, and C), and further, the generated chemical reaction layer is scraped off by the mechanical scraping action of the abrasive grains, realizing high-quality and high-efficiency removal of silicon carbide.

Effects of the Invention

[0019] The chemical mechanical composite processing method for the surface of silicon carbide of the present invention has the following beneficial effects: 1. By combining chemical reaction and mechanical removal, a silicon carbide surface without damage can be obtained, and the degree of damage is much smaller than that of grinding. 2. The removal efficiency of silicon carbide of the present invention is much higher than that of chemical mechanical polishing. 3. The present invention effectively avoids the problem of waste liquid pollution in the grinding and polishing processes.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Embodiments for Carrying out the Invention

[0021] Hereinafter, in order to further explain the technical solution of the present invention, the present invention will be described in detail with specific embodiments.

[0022] A chemical mechanical composite processing method for the surface of silicon carbide. As shown in Figure 1, first, a grinding and polishing tool 1 containing a composite active metal and abrasive grains and silicon carbide 2 are respectively attached to the machine base of the grinding and polishing equipment. Then, under the action of an external force, the silicon carbide 2 is pressed against the surface of the grinding and polishing tool 1. Finally, the grinding and polishing tool 1 rotating at high speed and the silicon carbide 2 are relatively moved, and further high-speed friction is generated to form a processing form of a chemical-mechanical composite cycle, including steps of realizing grinding or polishing of the surface of silicon carbide. The process of the chemical-mechanical composite cycle is that the active metal on the grinding and polishing tool 1 and the surface of the silicon carbide 2 undergo a chemical reaction by friction induction to generate a chemical reaction layer 3. Then, the chemical reaction layer 3 is scraped off by the mechanical action of the abrasive grains, exposing the surface of the new silicon carbide 2, causing a chemical reaction again to generate the chemical reaction layer 3, and then being mechanically scraped off again by the abrasive grains. By such a cycle action, a processing form of a chemical-mechanical composite cycle is formed.

[0023] The grinding and polishing tool 1 is formed by hot pressing and sintering an active metal and abrasive grains at a volume ratio of 7:1 to 1:1.

[0024] The active metal is a metal that reacts chemically with the C plane of the silicon carbide 2 or the Si plane of the silicon carbide 2.

[0025] The reactive metal that chemically reacts with the C-plane of silicon carbide 2 includes one or more of iron, cobalt, nickel, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tungsten, aluminum, and niobium. When the gas atmosphere of high-speed friction is an inert gas atmosphere, the generated chemical reaction layer contains metal silicide and C, or metal carbide and Si, or metal carbide and metal silicide. When the gas atmosphere of high-speed friction contains oxygen gas, the generated chemical reaction layer further contains silicon dioxide.

[0026] The reactive metal that chemically reacts with the Si-plane of silicon carbide 2 includes one or more of cobalt, nickel, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tungsten, aluminum, and niobium. When the gas atmosphere of high-speed friction is an inert gas atmosphere, the generated chemical reaction layer contains metal silicide and C, or metal carbide and Si, or metal carbide and metal silicide. When the gas atmosphere of high-speed friction contains oxygen gas, the generated chemical reaction layer further contains silicon dioxide.

[0027] The reactive metal is one or a combination of a plurality of a single metal and a metal alloy.

[0028] The abrasive grains include one or a combination of a plurality of aluminum oxide, cubic boron nitride, diamond, silicon nitride, and silicon carbide.

[0029] High-speed friction is dry friction or wet friction. The gas atmosphere of high-speed friction is at least one of an air atmosphere, a lean atmosphere, and an inert gas atmosphere. The temperature of high-speed friction is room temperature or high temperature. The speed of high-speed friction is 1 to 50 m / s. The pressure of high-speed friction is 0.1 to 1 Mpa.

[0030] As shown in Fig. 2, the grinding and polishing equipment includes a high-speed surface plate in which a spindle 101 is driven to rotate by a rotation mechanism, and a linear motion stage that is mounted above the high-speed surface plate and is driven to move up and down by a transmission mechanism. The grinding and polishing tool 1 is attached to the spindle 101 of the high-speed surface plate, and the silicon carbide 2 is attached to the jig 102 of the linear motion stage. The grinding and polishing equipment is a device well-known in the industry.

[0031] In Example 1, a chemical mechanical composite processing method for the surface of silicon carbide, comprising: Step 1 of preparing a grinding and polishing tool, first uniformly mixing iron powder and brown corundum (the main component is alumina) at a volume ratio of 3:2, then sieving through a 100-mesh sieve, and then hot pressing and sintering the obtained mixture. In a vacuum hot pressing sintering machine, the temperature is raised to 300 °C at a heating rate of 3 °C / min, then the temperature is raised to 900 °C at a heating rate of 5 °C / min, then held for 30 min, and finally cooled in the furnace to room temperature for sintering and forming to obtain a grinding and polishing tool; Step 2 of, after attaching the grinding and polishing tool, attaching the grinding and polishing tool to the spindle of the high-speed surface plate of the grinding and polishing equipment, and attaching the silicon carbide to be ground and polished to the jig of the linear motion stage; and Step 3 of, finally, by driving the linear motion stage, pressing the silicon carbide against the surface of the grinding and polishing tool, causing the high-speed rotating grinding and polishing tool and the silicon carbide to move relative to each other, and further generating high-speed friction to form a processing mode of a chemical-mechanical composite cycle to realize grinding and polishing of the surface of the silicon carbide.

[0032] In this example, the high-speed friction is dry friction performed at room temperature in an air atmosphere. The speed of the high-speed friction is 10 m / s, the pressure is 0.2 Mpa, and the time is 10 min.

[0033] In this embodiment, during the chemical-mechanical composite cycle process, iron powder in the grinding and polishing tool and the C plane of silicon carbide undergo a chemical reaction due to frictional induction, generating a chemical reaction layer containing FeSi, C, and SiO2. Next, the chemical reaction layer is scraped off by the mechanical action of abrasive brown corundum, exposing the surface of the new silicon carbide, causing a chemical reaction again to generate a chemical reaction layer, and then being mechanically scraped off again by the abrasive grains. Through such a cyclic action, the processing form of the chemical-mechanical composite cycle is formed.

[0034] In Example 2, a chemical-mechanical composite processing method for the surface of silicon carbide, comprising: Step 1 of preparing a grinding and polishing tool, first uniformly mixing nickel powder and white corundum (the main component is alumina) at a volume ratio of 3:1, then sieving through a 100-mesh sieve, and then hot-pressing and sintering the obtained mixture. In a vacuum hot-pressing sintering machine, the temperature is raised to 300 °C at a heating rate of 3 °C / min, then raised to 900 °C at a heating rate of 5 °C / min, then held for 30 min, and finally furnace-cooled to room temperature to obtain a sintered and formed grinding and polishing tool; Step 2 of attaching the grinding and polishing tool, after attaching the grinding and polishing tool, attaching the grinding and polishing tool to the spindle of the high-speed surface plate of the grinding and polishing equipment, and attaching the silicon carbide to be ground and polished to the fixture of the linear stage; and finally, by driving the linear stage, pressing the silicon carbide against the surface of the grinding and polishing tool, making the high-speed rotating grinding and polishing tool and the silicon carbide move relative to each other, and further generating high-speed friction to form the processing form of the chemical-mechanical composite cycle and realize the grinding and polishing of the surface of silicon carbide, which is Step 3 of the grinding and polishing process.

[0035] In this embodiment, the high-speed friction is dry friction carried out at room temperature in an atmospheric environment. The speed of the high-speed friction is 2 m / s, the pressure is 0.4 Mpa, and the time is 25 min.

[0036] In this embodiment, the process of the chemical-mechanical composite cycle is that nickel powder in the grinding and polishing tool reacts chemically with the C surface and Si surface of silicon carbide due to frictional induction to generate a chemical reaction layer containing Ni2Si, C, and SiO2. Next, the chemical reaction layer is scraped off by the mechanical action of the abrasive white alumina, exposing the surface of the new silicon carbide, causing a chemical reaction again to generate a chemical reaction layer, and then being mechanically scraped off again by the abrasive grains. Such a cyclic action forms the processing mode of the chemical-mechanical composite cycle.

[0037] The chemical-mechanical composite processing method for the surface of silicon carbide according to the present invention has the following beneficial effects: 1. By combining chemical reaction and mechanical removal, a damage-free surface of silicon carbide can be obtained, and the degree of damage is much smaller than that of grinding; 2. The removal efficiency of silicon carbide according to the present invention is much higher than that of chemical-mechanical polishing; 3. The present invention effectively avoids the problem of waste liquid pollution in the grinding and polishing processes.

[0038] The above embodiments and drawings do not limit the product form and specifications of the present invention. Those skilled in the art can make appropriate changes or modifications without departing from the scope of the claims of the present invention.

Explanation of Reference Signs

[0039] 1 Grinding and polishing tool, 2 Silicon carbide, 3 Chemical reaction layer, 101 Spindle, 102 Fixture

Claims

1. First, attach a grinding and polishing tool containing a composite active metal and abrasive grains and silicon carbide to the machine base of a grinding and polishing device respectively. Then, press the silicon carbide against the surface of the grinding and polishing tool by the action of an external force. Finally, make the grinding and polishing tool rotating at high speed and the silicon carbide move relative to each other, generating high-speed friction, causing a chemical reaction between the active metal and the silicon carbide, and further removing the chemical reaction layer by mechanical action to form a processing pattern of a chemical-mechanical composite cycle and realize grinding or polishing of the surface of silicon carbide, including the steps of The process of the chemical-mechanical composite cycle includes the steps that the surfaces of the active metal and the silicon carbide in the grinding and polishing tool undergo a chemical reaction due to friction to generate a chemical reaction layer, and then the chemical reaction layer is scraped off by the mechanical action of the abrasive grains, exposing the surface of the new silicon carbide, causing a chemical reaction again to generate a chemical reaction layer, and further being mechanically scraped off again by the abrasive grains. The grinding and polishing tool is formed by hot press sintering an active metal and abrasive grains at a volume ratio of 7:1 to 1:

1. The active metal is a metal that reacts with the terminal atoms on the C plane of silicon carbide or the Si plane of silicon carbide. The high-speed friction is dry friction or wet friction. The gas atmosphere of the high-speed friction is at least one of an air atmosphere, a lean atmosphere, and an inert gas atmosphere. The temperature of the high-speed friction is room temperature or high temperature. The speed of the high-speed friction is 1 to 50 m / s. The pressure of the high-speed friction is 0.1 to 1 MPa. A chemical-mechanical composite processing method for the surface of silicon carbide is characterized by the above.

2. The active metal that reacts with the C plane of silicon carbide includes one or more of iron, cobalt, nickel, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tungsten, aluminum, and niobium. The chemical-mechanical composite processing method for the surface of silicon carbide according to Claim 1 is characterized by this.

3. The active metal that reacts with the Si plane of silicon carbide includes one or more of cobalt, nickel, manganese, chromium, titanium, vanadium, zirconium, molybdenum, tungsten, aluminum, and niobium. The chemical-mechanical composite processing method for the surface of silicon carbide according to Claim 1 is characterized by this.

4. The method for chemically and mechanically composite machining the silicon carbide surface according to claim 1, wherein the active metal is one or a combination of a plurality of metal simple substances and metal alloys.

5. The method for chemically and mechanically composite machining the silicon carbide surface according to claim 1, wherein the abrasive grains include one or a combination of a plurality of aluminum oxide, cubic boron nitride, diamond, silicon nitride, and silicon carbide.

6. The method for chemically and mechanically composite machining the silicon carbide surface according to claim 1, wherein the grinding and polishing equipment includes a high-speed surface plate whose spindle is driven to rotate by a rotation mechanism and a linear motion stage that is driven to move up and down by a transmission mechanism, the grinding and polishing tool is attached to the spindle of the high-speed surface plate, and the silicon carbide is attached to the jig of the linear motion stage.

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