Enhanced AlGaN/GaN MOS(Metal Oxide Semiconductor)-HEMT(High Electron Mobility Transistor) device structure

Abstract

The invention provides an enhanced AlGaN / GaN MOS(Metal Oxide Semiconductor)-HEMT(High Electron Mobility Transistor) device structure. The structure comprises an Al2O3 substrate, a first intrinsic GaNbuffer layer, a second intrinsic GaN buffer layer, a GaN substrate layer, an AlGaN barrier layer and a GaN cap layer, wherein the first intrinsic GaN buffer layer, the second intrinsic GaN buffer layer, the GaN substrate layer, the AlGaN barrier layer and the GaN cap layer are sequentially stacked on the Al2O3 substrate, the GaN cap layer to the GaN substrate layer are etched to form a left sourceregion and a right drain region, metalized ohmic contact protruding out of a surface of the device is formed on surfaces of the left source region and the right drain region, a gate oxide layer is formed in a gate region corresponding to the GaN cap layer and the ohmic contact surface, and gate metal is formed on a surface of the gate oxide layer. The invention also provides a preparation methodof the device structure. The structure is advantaged in that reliability of the device can be improved, surface density and a channel driving current of the 2DEG can be improved, the gate leakage current of the device can be reduced, the preparation method can be compatible with the mainstream compound semiconductor process, the substrate quality is good, process repeatability is high, and large-scale manufacturing is easy.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to an enhanced AlGaN / GaN MOS-HEMT device structure and a preparation method thereof. Background technique [0002] The traditional semiconductor materials represented by silicon (Si) and gallium arsenide (GaAs) have gradually failed to meet the development of modern electronic technology under the requirements of radiation resistance, high temperature, high voltage and high power. Wide bandgap semiconductor GaN electronic devices can be used in high temperature, high voltage, high frequency and harsh environments, such as radar and wireless communication base stations and satellite communications. Due to its wide band gap, high breakdown voltage, high electron saturation drift velocity, excellent electrical and optical properties, and good chemical stability, GaN is favored in high-frequency, high-power, high-temperature electronic devices. The wide application of GaN device...

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Problems solved by technology

[0004] The inventors of the present invention have found through research that, from the perspective of the process technology of substrate material preparation, it is currently limited by the dislocation of GaN single crystals grown by heteroepitaxial technology using sapphire and silicon carbide (SiC) as substrates. The density is high, the performance is not satisfactory, the DC current gain of GaN HBT is still relatively small, and the process is not very stable; from the perspective of device design and application, the traditional GaN-based HEMT is a depletion type (normally on type), but power electronic equipment should adopt enhanced type (normally closed type), because this can greatly reduce the difficulty of integrated circuit design by offsetting the negative polarity power supply

[0005] In addition, although the industry has made a lot of efforts to improve the device structure of the enhancement mode AlGaN / GaN HEMT, in the practical application of power conversion, the threshold voltage of the enhancement mode HEMT device has not been significantly increased.

However, the conventional AlGaN / GaN HEMT has its inherent technical defects, such as its etching rate is not easy to control, the commonly used concave gate HEMT device is difficult to manufacture, the process repeatability is poor, and the uniformity of the threshold voltage is not good.

At the same time, the damage to the sample surface by physical etching significantly affects the device performance. For the use of fluorine ion implantation or plasma treatment, it usually causes damage and generates defects in the semiconductor material, thereby reducing the carrier mobility. These are currently Technical Problems Existing in Conventional AlGaN / GaN HEMT Structure Design

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