4H-SiC metal semiconductor field effect transistor having double high gates

Abstract

The invention relates to a 4H-SiC metal semiconductor field effect transistor having double high gates. 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 which are arranged from the bottom to the top in turn. The two sides of the N-type channel layer are respectively provided with a source cap layer and a drain cap layer. The surfaces of the source cap layer and the drain cap layer are respectively provided with a source electrode and a drain electrode. A gate electrode is formed on one side which is close to the source cap layer and arranged above the N-type channel layer. A left channel concave region, a right channel concave region and a middle channel concave region are formed at the left side, the right side and the middle of the N-type channel by the gate electrode. A left high gate region and a right high gate region are formed between the surface of the channel and the gate electrode. The advantages of the 4H-SiC metal semiconductor field effect transistor are that drain current is enhanced, breakdown voltage is enabled and the frequency characteristics are improved.

Description

technical field [0001] The invention belongs to the technical field of field effect transistors, in particular to a 4H-SiC metal semiconductor field effect transistor with double high gates. 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 application. [0003]...

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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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