SiC epitaxial wafer growing device and method

Abstract

The invention relates to the technical field of semiconductor processing, in particular to a SiC epitaxial wafer growing device and method.The SiC epitaxial wafer growing method is characterized in that a supporting structure capable of containing a baffle is additionally arranged on the lower surface of an upper half-moon structure, a silicon carbide substrate is placed on a wafer carrying disc, and before epitaxial growth, the baffle is placed on the supporting structure and located above the wafer carrying disc; in the epitaxial growth process of the silicon carbide substrate, external current is introduced into the supporting structure so that the baffle can be heated, 3C-SiC deposition and particle generation can be inhibited, after multiple times of epitaxial growth, the baffle is moved out of the reaction chamber and cleaned, and reuse is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor processing technology, and in particular to a SiC epitaxial wafer growth device and method. Background Art

[0002] The third-generation semiconductor silicon carbide (SiC) has the advantages of high breakdown field strength, high electron saturation drift rate, high thermal conductivity, high temperature resistance and radiation resistance. In recent years, SiC epitaxial wafers have been used to prepare power electronic devices and high-frequency devices, and are widely used in important fields such as new energy vehicles, rail transportation, 5G communications, photovoltaic power generation, and smart grids. At present, the mainstream method used in the industry to prepare SiC epitaxial wafers is chemical vapor deposition, which has the advantages of strong process controllability and good stability. The most commonly used equipment for large-scale production of SiC epitaxial wafers in the industry is horizontal monolithic SiC epitaxial equipment. Its advantage is that the thickness uniformity and doping concentration uniformity of SiC epitaxial wafers are good, but the disadvantage is that the surface of SiC epitaxial wafers is prone to fatal defects such as falling objects. This is because the temperature of the lower surface of the upper half of the moon above the SiC epitaxial wafer is relatively low, and the process gas is easy to grow and deposit on the lower surface of the upper half of the moon to form loose particles mainly composed of 3C-SiC crystal type, and gradually increase with the accumulation of growth thickness, and finally fall on the surface of the SiC epitaxial wafer to form falling object defects. Dropped objects are fatal defects of SiC epitaxial wafers. Not only will they cause device failure, but they will also induce other types of fatal defects such as triangle defects, resulting in a serious reduction in product yield.

[0003] In order to reduce the number and frequency of falling objects, the usual method is to break the vacuum in the reaction chamber, take out the upper half of the moon structure, polish and purge the lower surface of the upper half of the moon structure, and then put it back into the reaction chamber and restore the vacuum state of the reaction chamber. The above method is very time-consuming and labor-intensive, with high maintenance costs and seriously reduces production efficiency. Plating TaC film on the lower surface of the upper half of the moon structure can slow down the generation of SiC particles to a certain extent, but the preparation cost of TaC is high and the processing process is complicated, resulting in excessively high related production costs.

[0004] Therefore, the industry needs to develop new methods and devices to effectively reduce drop defects and improve the quality and yield of silicon carbide epitaxial wafers. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a SiC epitaxial wafer growth device and method to solve the problem of drop defects formed on the surface of SiC epitaxial wafers in the prior art.

[0006] A SiC epitaxial wafer growth device comprises a device body, wherein an upper half-moon structure and a lower half-moon structure are arranged in the device body, a reaction chamber is formed between the upper half-moon structure and the lower half-moon structure, a rotatable wafer carrier is arranged on the lower half-moon structure, a baffle assembly is connected to the upper half-moon structure, the baffle assembly comprises a supporting structure fixed to the lower end of the upper half-moon structure and electrically heated, and a baffle placed on the supporting structure, the supporting structure is used to heat the baffle, and the baffle is located above the wafer carrier.

[0007] Specifically, the lower half-moon structure is also provided with an air suspension device that rotates pneumatically, and the wafer carrier is placed on the air suspension device.

[0008] Specifically, the support structure includes two electric heating brackets and conductive terminals connected to the upper ends of the electric heating brackets.

[0009] Specifically, the lower end of the baffle is arranged at a slot for clamping the electric heating bracket.

[0010] Specifically, the SiC epitaxial wafer growth device also includes a robot for sending the wafer carrier and the baffle into or out of the reaction chamber.

[0011] A SiC epitaxial wafer growth method, using the SiC epitaxial wafer growth device, comprises the following steps: S1 moves a wafer carrier plate containing a silicon carbide substrate into a reaction chamber; S2 moves the baffle to the supporting structure; S3: introducing reaction gas into the reaction chamber and starting to increase the temperature, so that the silicon carbide substrate rotates, and the silicon carbide substrate starts epitaxial growth in the reaction chamber, and at the same time, a heating current is introduced into the support structure to increase the temperature of the baffle; S4 epitaxial growth is completed, the reaction gas is stopped from being introduced into the reaction chamber and the temperature is lowered, the silicon carbide substrate stops rotating, and the heating current stops being introduced into the support structure; S5: moving the wafer carrier out of the reaction chamber and taking out the grown silicon carbide epitaxial wafer.

[0012] Specifically, in step S3, the reaction gas is a combination of a carbon source gas (e.g., ethylene), a silicon source gas (e.g., trichlorosilane), a carrier gas (e.g., hydrogen), and a doping gas (e.g., nitrogen and trimethylaluminum), the temperature of the reaction chamber (13) is increased to 1450-1700° C., and the temperature of the baffle (22) is increased to above 1400° C.; In step S4, the temperature of the reaction chamber is lowered to below 200°C.

[0013] Specifically, after completing step S5, the following steps are also included: S6 After several epitaxial growths, the baffle is removed from the reaction chamber and cleaned for reuse.

[0014] Beneficial effects of the present invention: The SiC epitaxial wafer growth device and method of the present invention add a support structure for placing a baffle at the lower surface of the upper half-moon structure, place the silicon carbide substrate on a wafer carrier, and before epitaxial growth, place the baffle on the support structure, and the baffle is located above the wafer carrier; during the epitaxial growth of the silicon carbide substrate, an external current is passed through the support structure to heat the baffle, thereby inhibiting the deposition and particle generation of 3C-SiC; after several epitaxial growths, the baffle is removed from the reaction chamber and cleaned for reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 An exploded view of the SiC epitaxial wafer growth device of the present application; Figure 2 This is a schematic diagram of the structure of the SiC epitaxial wafer growth device of the present application; Figure 3 This is a schematic diagram of the structure of the baffle assembly and the manipulator of the present application.

[0016] The reference numerals are: device body 10 , upper half-moon structure 11 , lower half-moon structure 12 , reaction chamber 13 , wafer carrier 14 , baffle assembly 20 , support structure 21 , baffle 22 , air suspension device 15 , electric heating bracket 211 , conductive terminal 212 , card slot 221 , robot arm 30 , silicon carbide substrate 40 . DETAILED DESCRIPTION

[0017] The present invention provides a SiC epitaxial wafer growth device and method. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0018] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0019] like Figures 1 to 3As shown, this embodiment discloses a SiC epitaxial wafer growth device, including a device body 10, in which an upper half-moon structure 11 and a lower half-moon structure 12 are provided, a reaction chamber 13 is formed between the upper half-moon structure 11 and the lower half-moon structure 12, a rotatable wafer carrier 14 is provided on the lower half-moon structure 12, the upper half-moon structure 11 is connected to a baffle assembly 20, the baffle assembly 20 includes a support structure 21 fixed to the lower end of the upper half-moon structure 11 and powered to generate heat, and a baffle 22 placed on the support structure 21, the support structure 21 is used to heat the baffle 22, and the baffle 22 is located above the wafer carrier 14.

[0020] The SiC epitaxial wafer growth device of the present embodiment adds a support structure 21 on which a baffle 22 can be placed at the lower surface of the upper half-moon structure 11, and the silicon carbide substrate 40 is placed on the wafer carrier 14. Before epitaxial growth, the baffle 22 is placed on the support structure 21, and the baffle 22 is located above the wafer carrier 14; during the epitaxial growth of the silicon carbide substrate 40, an external current is passed through the support structure 21 to heat the baffle 22, thereby inhibiting the deposition and particle generation of 3C-SiC. After several epitaxial growths, the baffle 22 is removed from the reaction chamber 13 and cleaned for reuse.

[0021] It should be noted that the greater the heating current of the support structure 21, the less likely it is that silicon carbide deposition particles will be generated on the surface of the baffle 22, and therefore the cleaning frequency of the baffle 22 will be lower. However, an increase in the heating current will lead to an increase in the thermal budget, so in actual production, comprehensive consideration is required.

[0022] For further information, please refer to Figure 1 and Figure 2 In this embodiment, the lower half-moon structure 12 is also provided with an air suspension device 15 that rotates pneumatically. The wafer carrier 14 is placed on the air suspension device 15. The left side of the reaction chamber 13 is the air inlet. The central air suspension device 15 is blown and rotated by hydrogen or argon gas, thereby driving the silicon carbide substrate 40 on the wafer carrier 14 to rotate. The wafer carrier 14 is made of graphite material. The graphite material has excellent high temperature resistance, thermal conductivity and chemical stability, and can provide a stable thermal field environment for silicon carbide epitaxial growth.

[0023] As a preferred embodiment, the support structure 21 of this embodiment includes two electric heating brackets 211 and a conductive terminal 212 connected to the upper end of the electric heating bracket 211. The conductive terminal 212 is a bent structure, one end of which can extend out of the reaction chamber 13 and is connected to an electronic control device through a wire. The electronic control device provides a heating current to the electric heating bracket 211, and the size of the heating current is controllable.

[0024] For further information, please refer to Figure 3In this embodiment, the lower end of the baffle 22 is arranged at a slot 221 for clamping the electric heating bracket 211. After the baffle 22 is placed, the electric heating bracket 211 is clamped by the slot 221, which can prevent the baffle 22 from falling, and the structure is ingenious.

[0025] In addition, the SiC epitaxial wafer growth device also includes a robot 30 for sending the wafer carrier 14 and the baffle 22 into or out of the reaction chamber 13. The robot 30 can send the wafer carrier 14 and the baffle 22 into or out of the reaction chamber 13 to improve production efficiency.

[0026] This embodiment also discloses a SiC epitaxial wafer growth method, comprising the following steps: S1 uses the robot 30 to move the wafer carrier 14 with the silicon carbide substrate 40 into the reaction chamber 13; S2 uses the robot 30 to move the baffle 22 to the support structure 21; S3: introducing a reaction gas into the reaction chamber 13 and starting to raise the temperature to 1450-1700° C. The reaction gas is a combination of ethylene, trichlorosilane and trimethylaluminum. After the gas suspension device 15 is ventilated, the silicon carbide substrate 40 is rotated, and the silicon carbide substrate 40 begins to grow epitaxially in the reaction chamber 13. At the same time, a heating current is introduced into the support structure 21, so that the baffle 22 is heated to above 1400° C.; S4 epitaxial growth is finished, the reaction gas is stopped from being introduced into the reaction chamber 13 and the temperature is lowered to below 200° C., the gas suspension device 15 stops ventilating to stop the rotation of the silicon carbide substrate 40, and the heating current is stopped from being introduced into the support structure 21; S5: Using the robot 30, the wafer carrier 14 is moved out of the reaction chamber 13, and the grown silicon carbide epitaxial wafer is taken out; S6 After several epitaxial growths, the baffle plate 22 is removed from the reaction chamber 13, and the baffle plate 22 is cleaned by polishing, blowing, etc., so as to be used again.

[0027] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A SiC epitaxial wafer growth device, comprising a device body (10), wherein an upper half-moon structure (11) and a lower half-moon structure (12) are provided in the device body (10), a reaction chamber (13) is formed between the upper half-moon structure (11) and the lower half-moon structure (12), and a rotatable wafer carrier (14) is provided on the lower half-moon structure (12), characterized in that: The upper half-moon structure (11) is connected to a baffle assembly (20), the baffle assembly (20) comprising a support structure (21) fixed to the lower end of the upper half-moon structure (11) and electrically heated, and a baffle (22) placed on the support structure (21), the support structure (21) being used to heat the baffle (22), and the baffle (22) being located above the wafer carrier (14).

2. A SiC epitaxial wafer growth device according to claim 1, characterized in that: The lower half-moon structure (12) is also provided with an air suspension device (15) that rotates pneumatically, and the wafer carrier (14) is placed on the air suspension device (15).

3. The SiC epitaxial wafer growth device according to claim 1, characterized in that: The support structure (21) comprises two electric heating supports (211) and a conductive terminal (212) connected to the upper ends of the electric heating supports (211).

4. A SiC epitaxial wafer growth device according to claim 3, characterized in that: The lower end of the baffle (22) is arranged in a clamping groove (221) for clamping the electric heating bracket (211).

5. The SiC epitaxial wafer growth device according to claim 1, characterized in that: The SiC epitaxial wafer growth device also includes a robot (30) for sending the wafer carrier (14) and the baffle (22) into or out of the reaction chamber (13).

6. A method for growing a SiC epitaxial wafer, using the SiC epitaxial wafer growing apparatus according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: moving a wafer carrier (14) carrying a silicon carbide substrate (40) into a reaction chamber (13); S2 moves the baffle (22) to the support structure (21); S3: introducing a reaction gas into the reaction chamber (13) and starting to increase the temperature, so that the silicon carbide substrate (40) rotates, and the silicon carbide substrate (40) starts epitaxial growth in the reaction chamber (13), while simultaneously passing a heating current through the support structure (21) to increase the temperature of the baffle (22); S4 epitaxial growth is completed, reaction gas is stopped from being introduced into the reaction chamber (13) and the temperature is lowered, the silicon carbide substrate (40) stops rotating, and the heating current is stopped from being introduced into the support structure (21); S5: moving the wafer carrier (14) out of the reaction chamber (13) and taking out the grown silicon carbide epitaxial wafer.

7. A SiC epitaxial wafer growth method according to claim 6, characterized in that: In step S3, the reaction gas is a combination of carbon source gas, silicon source gas, carrier gas and doping gas, the temperature of the reaction chamber (13) is increased to 1450-1700° C., and the temperature of the baffle (22) is increased to above 1400° C.; In step S4, the temperature of the reaction chamber (13) is lowered to below 200°C.

8. A SiC epitaxial wafer growth method according to claim 6, characterized in that: After completing step S5, the following steps are further included: S6 After several epitaxial growths, the baffle (22) is removed from the reaction chamber (13) and the baffle (22) is cleaned for reuse.

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