Field effect transistor with gamma gate and recessed buffer layer and its preparation method

Abstract

The invention belongs to the technical field of field effect transistors and provides a field effect transistor equipped with a gamma-gate and a recessed buffer layer and a preparation method thereof, wherein the field effect transistor has a wide channel and a deep recess and is increased in output current and breakdown voltage and improved in frequency characteristic. An employed technical scheme is that a 4F-SiC semi-insulated substrate, a P-type buffer layer, an N-type channel layer are arranged from top to bottom; a source electrode cap layer and a drain electrode cap layer are arranged on both sides of the N-type channel layer respectively; the surface of the source electrode cap layer and the surface of the drain electrode cap layer are provided with a source electrode and a drain electrode respectively; a stepped gate electrode is disposed on a side, close to the source electrode cap layer, of the middle of the N-type channel layer; a left channel and a right channel are formed between both sides of the N-type channel layer and the gate electrode respectively; the low gate surface of the gate electrode is flush with the surface of the N-type channel layer; and a groove is disposed on the P-type buffer layer right under the low gate surface of the gate electrode.

Description

technical field [0001] The invention belongs to the technical field of field effect transistors, in particular to a field effect transistor with a Γ gate and a recessed buffer layer and a preparation method thereof. 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 t...

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Problems solved by technology

[0004] Although the breakdown voltage of the 4H-SiC MESFET with the double-recessed structure is increased due to the fact that half the length of the source side of the gate is recessed into the N-type channel layer, the saturation leakage current has not been substantially 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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