P-type heavily-doped silicon carbide film extension preparation method

Abstract

The invention discloses a P-type heavily-doped silicon carbide film extension preparation method, which mainly solves the problem that in the prior art, high-quality heavy doping of silicon carbide cannot be realized. The method comprises the following steps that: a silicon carbide underlay is firstly placed into a reaction chamber; the reaction chamber is heated in the hydrogen stream, and after the temperature reaches 1,400 DEG C, propane (C3H8) is added into the hydrogen stream; after the temperature reaches 1,580 DEG C, in-situ etching is performed on the underlay for 10 to 30 minutes; then the temperature of the reaction chamber is maintained at 1,580 DEG C, the air pressure is maintained at 100mbar, silane (SiH4) with a flow rate of 15 to 24 mL/min, C3H8 with a flow rate of 5 to 10 mL/min and trimethyl aluminium with a flow rate of 3.2*10<minus 5 mol/min) are added into the hydrogen stream of 20L/min to grow an extension layer; after the growth is completed, the extension layer is cooled in the hydrogen stream; and finally, argon is charged into the reaction chamber to the normal pressure. The doping concentration of the prepared silicon carbide extension layer is 4*1019cm<-3> to 4.6*1019cm<-3>, the doping is uniform, the surface is smooth, and the prepared silicon carbide extension layer can be used for producing a silicon carbide device.

Description

technical field [0001] The invention belongs to the technical field of semiconductor device manufacture, and in particular relates to a method for preparing a P-type heavily doped silicon carbide epitaxial layer by using the existing MOCVD growth process of silicon carbide material. Background technique [0002] Silicon carbide materials have good physical and electrical properties, and have extremely important application prospects in high-temperature, high-voltage, high-frequency, and radiation-resistant electronic devices. [0003] Silicon carbide is a wide bandgap semiconductor, and the intrinsic carrier can still maintain a low concentration at high temperature, so it can work at very high temperature. In the case of no avalanche breakdown, the maximum electric field strength that silicon carbide can withstand is more than 8 times that of silicon materials, which makes silicon carbide can be used to make high-voltage, high-power semiconductor devices, such as PiN diodes...

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Problems solved by technology

[0007] Li Zheyang et al.'s patent "Method for Epitaxial Growth of Highly Doped Silicon Carbide", proposed a high-doped semiconductor epitaxial growth process method, but under the given process conditions, the grown epitaxial layer concentration is 1× 10 18 cm -3 Around, some semiconductor devices, such as the emission region of BJT, need to use heavily doped epitaxial layer, the concentration should be 1×10 19 cm -3 Above, the above method cannot meet the requirements of preparing these devices, so it is necessary to study new process conditions to achieve a higher concentration of epitaxial layer doping

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