Normally-closed GaN-based MOSFET structure with high threshold voltage and high conduction performance and fabrication method thereof

Abstract

The invention relates to the technical field of semiconductor, in particular to a normally-closed GaN-based MOSFET structure with a high threshold voltage and high conduction performance and a fabrication method thereof. The fabrication method of the normally-closed GaN-based MOSFET structure with the high threshold voltage and high conduction performance comprises the following steps of firstly,providing a required substrate, sequentially and epitaxially growing a stress buffer layer, a GaN buffer layer, an AIN thin layer and an AlGaN thin layer on the substrate, and reserving the AlN thin layer and the AlGaN thin layer on a grid region by etching to obtain a substrate for epitaxy of a selection region; secondly, sequentially selecting a regional epitaxial GaN channel layer, a AIN insertion layer and a AIGaN barrier layer on the substrate to form a groove structure; and finally, depositing a grid dielectric layer, covering grid metal on a groove channel grid dielectric layer, and covering two ends of the grid with metal to form a source and a drain. By the fabrication method, the threshold voltage and the grid region mobility can be effectively improved, the channel resistance isreduced, and the conduction performance of the GaN MOSFET device is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, and more specifically, to a normally-off GaN-based MOSFET structure with high threshold voltage and high conduction performance and a preparation method thereof. Background technique [0002] As a representative of the third-generation wide-bandgap semiconductor materials, GaN materials have superior properties such as large bandgap width, high breakdown electric field strength, large saturated electron drift velocity, and high thermal conductivity. GaN-based power switching devices usually use two-dimensional electron gas with high concentration and high mobility at the interface of AlGaN / GaN heterostructure to work, so that the device has the advantages of small on-resistance and fast switching speed, and is very suitable for making high-power, high-frequency , High temperature power electronic devices. [0003] In the field of power electronics applications, in order to ensure the fail...

AI Technical Summary

Problems solved by technology

Completely removing the AlGaN layer in the gate area can increase the threshold voltage of the device, but it also brings problems such as low gate mobility, large on-resistance, and high interface state density.

Thinning the AlGaN layer in the gate region can alleviate this problem. However, due to the existence of the thin layer of AlGaN, there is a certain concentration of two-dimensional electron gas in the gate region, which makes the threshold voltage of the device smaller.

In addition, traditional thin barrier layer devices use methods such as etching to remove the AlGaN layer in the gate region. This method cannot achieve precise controllability of the thickness of the thin barrier layer, and will inevitably introduce lattice damage in the gate region.

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