Method for growing buffer layer of silicon carbide epitaxial material

Abstract

The invention discloses a method for growing a buffer layer of a silicon carbide epitaxial material. The comprises the following steps: switching between low C/Si ratio and high C/Si ratio at the end of the growth of a low-speed buffer layer, and quickly finishing the switching in a short time so as to quickly improve the C/Si ratio. By adopting the optimized process switching process between the buffer layer and the epitaxial layer, the carbon-silicon ratio (C/Si) is kept stable along with time in the switching process of low-speed buffer layer growth and high-speed epitaxial layer growth, and the carbon source flow and the silicon source flow adopted in the low-speed epitaxial stage are very low, so the increasing requirement of the C/Si ratio can be met by relatively small carbon source flow amplification, defects and stress introduced in the speed switching process from low speed to high speed are reduced, the defect density of the epitaxial material is reduced, and the growth of the high-quality silicon carbide epitaxial material is realized.

Description

technical field [0001] The invention relates to a buffer layer growth method for epitaxial materials, in particular to a buffer layer growth method for silicon carbide epitaxial materials. Background technique [0002] At present, the third-generation wide-bandgap semiconductor materials represented by silicon carbide (SiC) have the advantages of wide band gap, high thermal conductivity, high breakdown strength, high electron saturation drift velocity, high hardness, etc., and also have strong chemical properties. Stability makes silicon carbide have many advantages in application, especially suitable for high power, high temperature and high frequency applications. [0003] The SiC device structure must be realized by epitaxy. At the same time, the performance advantages of SiC materials are particularly significant at high voltages, so it is necessary to grow thick layers of homoepitaxial growth. However, with the increase in the thickness of the epitaxial layer and the c...

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Problems solved by technology

However, with the increase in the thickness of the epitaxial layer and the complexity of the multilayer structure, the defects in the epitaxial layer will also increase, which will greatly affect the semiconductor performance in terms of withstand voltage and mobility, and ultimately affect the finished product of the power semiconductor device. Serious impact on rate and performance

The substrate for SiC epitaxial materials is generally an off-axis substrate, and the SiC substrate itself has crystal defects during the growth process, and off-axis cutting is also easy to introduce new defects.

During the epitaxial growth process, substrate surface defects will extend to the epitaxial layer and be easily amplified, directly affecting the performance of chips and devices

However, the epitaxial layer (drift layer) of the existing power electronic devices is a low-doped thick-layer epitaxial material, which adopts a high-speed epitaxial process with a high C / Si ratio at the inlet end, which is prone to unstable C / Si ratio and doping in the buffer layer. The case of low efficiency

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