Method for preparing base-region graded doped silicon carbide thin film epitaxy layer

Abstract

The invention relates to a method for preparing a base-region graded doped silicon carbide thin film epitaxy layer. The method comprises the steps that 1, a silicon carbide substrate is placed in a reaction chamber of silicon carbide CVD equipment, and the reaction chamber is vacuated; 2, H2 is introduced into the reaction chamber till the air pressure of the reaction chamber reaches 100 mbar, the air pressure of the reaction chamber is kept constant, the flow of H2 is gradually increased to 60 L / min, and gas continues to be introduced into the reaction chamber; 3, a high-frequency coil induction heater RF is started, the power of the heater is gradually increased, and when the temperature of the reaction chamber gradually rises to 1,400 DEG C, in-situ etching is carried out; and 4, when the temperature of the reaction chamber reaches 1,580 DEG C to 1,600 DEG C, the temperature and pressure are kept constant, the flow of an Al source is set, C3H8 and SiH4 are introduced into the reaction chamber, and the P-type graded doped silicon carbide thin film epitaxy layer is slowly grown by gradually adjusting the flow of the Al source introduced into the reaction chamber. According to the method, the CVD equipment of silicon carbide is utilized, the silicon carbide epitaxy layer with the controllable longitudinal doping concentration gradient is prepared, and the requirement for preparation of the gradient low-doped epitaxy layer is met.

Description

technical field [0001] The invention relates to the technical field of semiconductor device manufacturing, in particular to an epitaxy preparation method of a base region graded doped silicon carbide thin film. Background technique [0002] Silicon carbide has the advantages of wide band gap, high thermal conductivity, high breakdown strength, high electron saturation drift speed, high hardness, etc., and also has strong chemical stability. These excellent physical and electrical properties make silicon carbide have many advantages in applications. The band gap enables the intrinsic carrier of silicon carbide to maintain a low concentration at high temperature, so it can work at very high temperature. The high breakdown field strength allows silicon carbide to withstand high electric field strengths, which makes silicon carbide useful for making high-voltage, high-power semiconductor devices. High thermal conductivity makes silicon carbide have good heat dissipation, which...

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Problems solved by technology

However, due to the high bond strength of silicon carbide, the doping in the device manufacturing process cannot use the diffusion process, and can only be controlled by epitaxy and high-temperature ion implantation.

High-temperature ion implantation will cause a lot of lattice damage and form a large number of lattice defects, which are difficult to completely eliminate even with annealing, seriously affecting the performance of the device, and the efficiency of ion implantation is very low, so it is not suitable for large-area doping

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