4h-sic metal-semiconductor field-effect transistor with stepped buffer layer structure

Abstract

The invention discloses a 4H-SiC metal semiconductor field effect transistor with a step buffer layer structure. The 4H-SiC metal semiconductor field effect transistor comprises a 4H-SiC semi-insulating substrate, a P-type buffer layer and an N-type channel layer from the bottom to the top. The two sides of the N-type channel layer are respectively provided with a source electrode cap layer and a drain electrode cap layer. The surface of the source electrode cap layer and the drain electrode cap layer is respectively provided with a source electrode and a drain electrode. A gate electrode is formed on one side which is arranged above the N-type channel layer and close to the source electrode cap layer. A concave gate source drift region is formed between the gate electrode and the source electrode cap layer. A concave gate drain drift region is formed between the gate electrode and the drain electrode cap layer. The position, which is arranged on the upper end surface of the P-type buffer layer and close to the source electrode cap layer, is provided with a groove. One side, which is arranged in the groove and close to the drain electrode cap layer, is provided with two steps. The 4H-SiC metal semiconductor field effect transistor with the step buffer layer structure has advantages of being stable in breakdown voltage and high in output drain electrode current.

Description

technical field [0001] The invention relates to the technical field of field effect transistors, in particular to a 4H-SiC metal semiconductor field effect transistor with a ladder buffer layer structure. Background technique [0002] SiC materials have outstanding material and electrical properties such as wide band gap, high breakdown electric field, high saturated electron migration velocity, and high thermal conductivity, making them suitable for high-frequency and high-power device applications, especially high temperature, high voltage, aerospace, satellite, etc. It has great potential in high-frequency high-power device applications in harsh environments. In SiC allomorphs, the electron mobility of 4H-SiC with hexagonal close-packed wurtzite structure is nearly three times that of 6H-SiC, so 4H-SiC materials are used in high-frequency and high-power devices, especially in metal-semiconductor fields. Effect transistor (MESFET) occupies a major position in the applicat...

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Problems solved by technology

[0004] Compared with the double recessed structure, although the breakdown voltage of the above-mentioned recessed source / drain drift region 4H-SiC MESFET is increased due to the reduction of the thickness of the drift region between the gate and drain, the saturation leakage current is not improved

And in practice, the process of reactive ion etching (RIE) will form lattice damage on the surface of the drift region of the device, resulting in a decrease in the effective mobility of carriers in the N-type channel layer, thereby reducing the drain current. In terms of current output characteristics manifested as a degradation of the saturation current

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