4H-SiC metal semiconductor field effect transistor with P-type doped region and recessed buffer layer

Abstract

The invention relates to the technical field of field effect transistors, and discloses a 4H-SiC metal semiconductor field effect transistor with a P-type doped region and a recessed buffer layer. The field effect transistor comprises a 4H-SiC semi-insulating substrate, a P-type buffer layer and an N-type channel layer from bottom to top, the surface of the N-type channel layer is provided with a source electrode cap layer and a drain electrode cap layer, a source electrode and a drain electrode are arranged on the surface of the source electrode cap layer and the surface of the drain electrode cap layer respectively, a gate electrode is formed on the side, close to the source electrode cap layer, of the upper surface of the N-type channel, a concave gate-drain drift region is formed between the gate electrode and the drain electrode cap layer, a gate-source drift region is formed between the gate electrode and the source electrode cap layer, the surface of the concavegate-drain drift region is provided with a P-type doped region close to a gate corner, and the P-type buffer layer below the gate-source drift region is recessed downwards to form a recessed buffer layer. The field effect transistor has the advantages that the breakdown voltage is greatly improved, and the drain output current is stable.

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 P-type doped region and a recessed buffer layer. Background technique [0002] Silicon carbide (SiC), as a third-generation new semiconductor material, exhibits excellent characteristics in many aspects, for example, it has 2-4×10 6 The high breakdown electric field of V / cm, the wide forbidden band of 3.3eV, the high thermal conductivity of 3.5W / (cm K) and the 2.7×10 7 cm / s high electron saturation velocity and other excellent characteristics. Among the many isomorphs of SiC, 4H-SiC has high electron saturation velocity and high electron mobility (the electron mobility of 4H-SiC is about twice that of 6H-SiC), and the ionization energy of its donor impurities Relatively small and low anisotropy, its overall performance is the most superior. Therefore, in radio frequency microwave power devices, 4H-SiC...

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Problems solved by technology

Although compared with the traditional results, the saturation drain current and frequency of the double-recessed 4H-SiC MESFET have been greatly improved, but its breakdown voltage is much lower than that of the traditional structure.

This is an unavoidable problem that needs to be balanced in power devices: a wide channel brings a large saturated drain current, but at the same time it also reduces the effective resistance of the channel, resulting in a deterioration of the breakdown voltage

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