Al2O3/AlN/GaN/AlN MOS-HEMT device and manufacturing method thereof

Abstract

The invention discloses an Al2O3 / AlN / GaN / AlN MOS-HEMT device and a manufacturing method thereof. The Al2O3 / AlN / GaN / AlN MOS-HEMT device comprises an AlN buffer layer 7, a GaN channel layer 6 and an AlN barrier layer 5 which are formed on an AlN monocrystalline substrate 8 in sequence, an Al2O3 grid medium layer 4, a source electrode 1 and a drain electrode 3 which are formed on the AlN barrier layer 5 as well as a grid electrode 2 formed on the Al2O3 grid medium layer 4. The Al2O3 / AlN / GaN / AlN MOS-HEMT device is characterized in that the traditional sapphire substrate is replaced by the AlN monocrystalline substrate and the self heating effect of the device can be reduced by using the high heat conductivity property of the AlN material. The traditional semi-insulated GaN epitaxial layer is replaced by the AlN buffer layer with high resistance and only the GaN channel layer is left, thereby parasitic heat conductivity and leakage current of the GaN epitaxial layer can be greatly reduced. In addition, the formed AlN / GaN / AlN quantum well structure further improves the binding force of two-dimensional electron gas in the channel, and thereby the current collapse effect can be reduced.

Description

technical field [0001] The present invention relates to electronic component technology, specifically refers to an Al 2 o 3 / AlN / GaN / AlN MOS-HEMT devices, which can be used in high-temperature, high-frequency, high-power applications, high-power switches, and digital circuits. Background technique [0002] Due to its wide application in high-power, high-frequency and high-temperature amplifiers, AlGaN / GaN heterojunction high electron mobility transistors (HEMTs) have become a research hotspot in the semiconductor field over the past decade. However, with the shrinking of the device size, a series of problems such as current collapse, self-heating effect, leakage current and short channel effect seriously restrict the further development of the device. In order to obtain higher power HEMT devices, some variants based on the AlGaN / GaN structure have been proposed. For example, in 2004, W. Lanfort of the State University of New York and others proposed the AlGaN / InGaN / GaN het...

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Problems solved by technology

However, there are also some problems with the sapphire substrate: first, the lattice mismatch and thermal stress mismatch between the sapphire substrate and the epitaxial layer will generate a large number of defects in the epitaxial layer, and at the same time cause difficulties for subsequent device processing; and the sapphire substrate The poor thermal conductivity (about 0.35W / cmK) will cause the self-heating effect of the HEMT device under high current operation and affect the device performance

The use of semi-insulating GaN buffer layer is easy to cause many problems: first, the current collapse effect under radio frequency working conditions reduces the microwave output power, which is mainly caused by surface traps and GaN body traps capturing hot electrons in the channel; secondly, semi-insulating GaN buffer The layer introduces parasitic current, which reduces the performance of the device, and in severe cases, the HEMT device cannot be pinched off

However, this structure still has great disadvantages. First, the self-heating effect is obvious, which is mainly due to the poor thermal conductivity of the sapphire substrate; The leakage current of the layer seriously affects the performance of the device; the third is the current collapse effect during high-voltage operation, which is mainly caused by the hot electron overflow channel formed by the two-dimensional electron gas under the acceleration of the high electric field being captured by the trap in the buffer layer

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