Gallium nitride normally-off device with mixed gate electrode structure and preparation method of gallium nitride normally-off device

Abstract

The invention discloses a gallium nitride normally-off device with a mixed gate electrode structure and a preparation method of the gallium nitride normally-off device. The gallium nitride normally-off device comprises a buffer layer, a GaN channel layer, an AlGaN layer and a P-GaN cap layer which are sequentially arranged on a substrate layer, two ohmic electrodes which are arranged on the AlGaN layer, gate dielectric layers which are arranged on the P-GaN cap layer and on the two sides of the P-GaN cap layer, a passivation layer which is arranged on the AlGaN layer between the ohmic electrode and the gate dielectric layer on the two sides of the P-GaN cap layer, and a gate electrode which is arranged on the gate dielectric layer and filled in the groove of the gate dielectric layer. The gate electrode on the gate dielectric layer on the P-GaN cap layer and the gate electrodes filled in the plurality of grooves form a mixed gate structure of an MIS gate electrode structure and a Schottky gate electrode structure; and the gate electrodes on the gate dielectric layers on the two sides of the P-GaN cap layer and the gate dielectric layers on the two sides of the P-GaN cap layer form a field plate structure. The threshold voltage of the gate electrode of the device is improved, the switching frequency of the device is improved, and meanwhile the long-term reliability of the gate electrode of the device is improved.

Description

technical field [0001] The invention belongs to the technical field of semiconductor power devices, and in particular relates to a gallium nitride normally-off device with a mixed gate electrode structure and a preparation method thereof. Background technique [0002] Wide-bandgap semiconductor materials represented by gallium nitride (GaN) have a high critical breakdown electric field, which can achieve lower capacitance and on-resistance at the same breakdown voltage, and are recognized as next-generation power device materials. Therefore, the development of gallium nitride (GaN) power devices to replace traditional silicon (Si)-based devices is a key means to improve power utilization efficiency and alleviate the energy crisis, and is expected to play a pivotal role in emerging markets. As a representative device of gallium nitride (GaN), a high electron mobility transistor (HEMT) based on an AlGaN / GaN epitaxial structure, due to its unique high mobility two-dimensional e...

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Problems solved by technology

[0004] However, at present, the threshold voltage of the gate electrode of the P-GaN cap layer high electron mobility transistor (HEMT) is maintained at about 2V, which cannot meet the requirements for the threshold voltage of the gate electrode in actual operation.

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