Epitaxial growth process of silicon carbide substrate

Abstract

The invention discloses an epitaxial growth process of a silicon carbide substrate. The epitaxial growth process comprises the following steps: etching the silicon carbide substrate placed in a reaction chamber; etching gas hydrogen is introduced into the reaction cavity, and the etching temperature is 1750-1800 DEG C; growing a buffer layer on the etched silicon carbide substrate; in the growth of the buffer layer, carbon source gas, silicon source gas and auxiliary gas are introduced into the reaction cavity, the flow of the carbon source gas is 15-35 sccm, the flow of the silicon source gas is 45-65 sccm, and the flow of the auxiliary gas is 8-14 sccm; alternately growing a first epitaxial layer and a second epitaxial layer on the buffer layer; the method has the advantages that growth of epitaxial layers of different parameter types can be achieved on the premise of the same technology, the technological process is simple, the production time is short, and the production efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to an epitaxial growth process for silicon carbide substrates. Background Technology

[0002] Silicon carbide epitaxy is a widely used fabrication method in the semiconductor field. The epitaxial process involves growing a new single-crystal layer on a single-crystal substrate along its original crystal axis; this newly grown single-crystal layer is the epitaxial layer. Unlike silicon device fabrication, almost all silicon carbide power electronic device fabrications are implemented on homogeneous 4H-SiC epitaxial layers. Multilayer silicon carbide epitaxial layers with different doping methods have various applications, including power amplifiers, RF amplifiers, high-frequency switches, optoelectronic devices, sensors, and photovoltaic cells. Research shows that silicon carbide devices, compared to traditional silicon-based devices, possess better voltage and high-temperature resistance, higher switching frequencies, and superior device parameters. However, traditional CVD growth furnaces still present many unresolved problems in developing multilayer epitaxial processes.

[0003] Traditional processes for preparing multilayer epitaxial layers with different doping are complex, require overcoming numerous problems, are inefficient, and are costly. Therefore, it is necessary to develop an efficient and low-cost epitaxial growth process for silicon carbide substrates. After searching, no technical solution identical to this invention was found. Summary of the Invention

[0004] The main technical problem solved by this invention is to provide a high-efficiency and low-cost epitaxial growth process for silicon carbide substrates, thereby solving one or more of the problems in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention adopts a technical solution as follows: an epitaxial growth process for silicon carbide substrates, the innovation of which is that it includes the following steps:

[0006] 1) Etch the silicon carbide substrate placed in the reaction chamber; introduce hydrogen as an etching gas into the reaction chamber, and etch at a temperature of 1750-1800℃;

[0007] 2) A buffer layer is grown on the etched silicon carbide substrate; during the growth of the buffer layer, carbon source gas, silicon source gas and auxiliary gas are introduced into the reaction chamber, with the flow rate of carbon source gas being 15-35 sccm, the flow rate of silicon source gas being 45-65 sccm, and the flow rate of auxiliary gas being 8-14 sccm.

[0008] 3) The first epitaxial layer and the second epitaxial layer are alternately grown on the buffer layer;

[0009] The first epitaxial layer includes an X-type epitaxial layer. During the growth of the X-type epitaxial layer, carbon source gas, silicon source gas, and auxiliary gas are also introduced into the reaction chamber. The carbon / silicon ratio of the carbon source gas to the silicon source gas is 0.9-1.1, and the flow rate of the X-type auxiliary gas is 45-50 sccm.

[0010] The second epitaxial layer includes a Y-type epitaxial layer. During the growth of the Y-type epitaxial layer, carbon source gas, silicon source gas, and auxiliary gas are also introduced into the reaction chamber. The carbon / silicon ratio of the carbon source gas to the silicon source gas is 2.5-3.2, and the flow rate of the Y-type doped gas is 0.5-2 sccm.

[0011] The buffer layer, the first epitaxial layer, and the second epitaxial layer are grown in the reaction chamber. After the second epitaxial layer is grown, the silicon carbide substrate is transferred to the buffer chamber, and the reaction chamber is cleaned. The first epitaxial layer continues to grow on the silicon carbide substrate transferred from the buffer chamber to the cleaned reaction chamber. The buffer chamber and the reaction chamber belong to the same epitaxial growth equipment.

[0012] In some implementations, the thickness of the buffer layer is 1.4-1.5 μm.

[0013] In some implementations, the thickness of the first epitaxial layer is 3-10 μm.

[0014] In some implementations, the thickness of the second epitaxial layer is 4-5 μm.

[0015] In some implementations, a purification gas is introduced into the buffer chamber when the silicon carbide substrate is transferred into the buffer chamber.

[0016] The beneficial effects of this invention are: this technical solution can achieve the growth of epitaxial layers with different parameters under the premise of the same process, the process flow is simple, the production time is short, and the production efficiency is high. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The embodiments of the present invention include:

[0019] An epitaxial growth process for a silicon carbide substrate includes the following steps:

[0020] 1) Etch the silicon carbide substrate placed in the reaction chamber; introduce hydrogen as an etching gas into the reaction chamber, and etch at a temperature of 1750-1800℃;

[0021] 2) A buffer layer is grown on the etched silicon carbide substrate; during the growth of the buffer layer, carbon source gas, silicon source gas and auxiliary gas are introduced into the reaction chamber, with the flow rate of carbon source gas being 15-35 sccm, the flow rate of silicon source gas being 45-65 sccm, and the flow rate of auxiliary gas being 8-14 sccm.

[0022] 3) The first epitaxial layer and the second epitaxial layer are alternately grown on the buffer layer;

[0023] The first epitaxial layer includes an X-type epitaxial layer. During the growth of the X-type epitaxial layer, carbon source gas, silicon source gas, and auxiliary gas are also introduced into the reaction chamber. The carbon / silicon ratio of the carbon source gas to the silicon source gas is 0.9-1.1, and the flow rate of the X-type auxiliary gas is 45-50 sccm.

[0024] The second epitaxial layer includes a Y-type epitaxial layer. During the growth of the Y-type epitaxial layer, carbon source gas, silicon source gas, and auxiliary gas are also introduced into the reaction chamber. The carbon / silicon ratio of the carbon source gas to the silicon source gas is 2.5-3.2, and the flow rate of the Y-type doped gas is 0.5-2 sccm.

[0025] The buffer layer, the first epitaxial layer, and the second epitaxial layer are grown in the reaction chamber. After the second epitaxial layer is grown, the silicon carbide substrate is transferred to the buffer chamber, and the reaction chamber is cleaned. The first epitaxial layer continues to grow on the silicon carbide substrate transferred from the buffer chamber to the cleaned reaction chamber. The buffer chamber and the reaction chamber belong to the same epitaxial growth equipment.

[0026] In this embodiment, the thickness of the buffer layer is 1.4-1.5 μm.

[0027] In this embodiment, the thickness of the first epitaxial layer is 3-10 μm.

[0028] In this embodiment, the thickness of the second epitaxial layer is 4-5 μm.

[0029] In this embodiment, a purification gas is introduced into the buffer chamber when the silicon carbide substrate is transferred into the buffer chamber.

[0030] The beneficial effects of this invention are: this technical solution can achieve the growth of epitaxial layers with different parameters under the premise of the same process, the process flow is simple, the production time is short, and the production efficiency is high.

[0031] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An epitaxial growth process for a silicon carbide substrate, characterized in that: Includes the following steps: 1) Etch the silicon carbide substrate placed in the reaction chamber; introduce hydrogen as an etching gas into the reaction chamber, and etch at a temperature of 1750-1800℃. 2) A buffer layer is grown on the etched silicon carbide substrate; during the growth of the buffer layer, carbon source gas, silicon source gas and auxiliary gas are introduced into the reaction chamber, with the flow rate of carbon source gas being 15-35 sccm, the flow rate of silicon source gas being 45-65 sccm, and the flow rate of auxiliary gas being 8-14 sccm. 3) The first epitaxial layer and the second epitaxial layer are alternately grown on the buffer layer; The first epitaxial layer includes an X-type epitaxial layer. During the growth of the X-type epitaxial layer, carbon source gas, silicon source gas, and auxiliary gas are also introduced into the reaction chamber. The carbon / silicon ratio of the carbon source gas to the silicon source gas is 0.9-1.1, and the flow rate of the X-type auxiliary gas is 45-50 sccm. The second epitaxial layer includes a Y-type epitaxial layer. During the growth of the Y-type epitaxial layer, carbon source gas, silicon source gas, and auxiliary gas are also introduced into the reaction chamber. The carbon / silicon ratio of the carbon source gas to the silicon source gas is 2.5-3.2, and the flow rate of the Y-type doped gas is 0.5-2 sccm. The buffer layer, the first epitaxial layer, and the second epitaxial layer are grown in the reaction chamber. After the second epitaxial layer is grown, the silicon carbide substrate is transferred to the buffer chamber, and the reaction chamber is cleaned. The first epitaxial layer continues to grow on the silicon carbide substrate transferred from the buffer chamber to the cleaned reaction chamber. The buffer chamber and the reaction chamber belong to the same epitaxial growth equipment.

2. The epitaxial growth process for a silicon carbide substrate according to claim 1, characterized in that: The thickness of the buffer layer is 1.4-1.5 μm.

3. The epitaxial growth process for a silicon carbide substrate according to claim 1, characterized in that: The thickness of the first epitaxial layer is 3-10 μm.

4. The epitaxial growth process for a silicon carbide substrate according to claim 1, characterized in that: The thickness of the second epitaxial layer is 4-5 μm.

5. The epitaxial growth process for a silicon carbide substrate according to claim 1, characterized in that: When the silicon carbide substrate is transferred into the buffer chamber, a purification gas is introduced into the buffer chamber.