GaN device based on component-gradient GaN MISFET and preparing method thereof

Abstract

The present invention discloses a GaN device based on component-gradual-changed GaN MISFET and its processing method. The device includes substrate (1), buffer layer (2), intrinsic GaN layer (3), AlN isolating layer (4) and source (7), drain (8), gate (9), in which component-gradual-changed AlGaN layer (5) and AlN cap layer (6) are orderly set on the AlN isolating layer. The process of the device includes: the GaN or AlN buffer layer are orderly extended on sapphire or silicon carbide substrate; the intrinsic GaN layer is deposited; the AlN isolating layer is deposited; the component-gradual-changed AlGaN is deposited; the AlN cap layer is deposited; two sides of the AlN cap layer on top and parts of two sides of component-gradual-changed AlGaN layer are separately etched to form a step structure which is high in central and low in two sides; ohmic contacts of the source and the drain and metal contact of the gate are separately made on different steps of the structure. The present invention has low drain current and high gate voltage, and can be used to process high power microwave devices.

Description

technical field [0001] The invention belongs to the technical field of microelectronics, and relates to a semiconductor device structure and a manufacturing method, in particular to a GaN device based on a composition gradient GaN MISFET and a preparation method, which can be used in the manufacture of high-power GaN devices. Background technique [0002] In recent years, the third-generation wide-bandgap semiconductor materials represented by SiC and GaN have large bandgap width, high critical field strength, high thermal conductivity, high carrier saturation rate, and high concentration of two-dimensional electron gas at the heterojunction interface. Its excellent characteristics have attracted widespread attention from people. In theory, high electron mobility transistor HEMT, heterojunction bipolar transistor HBT, light-emitting diode LED, laser diode LD and other devices made of these materials will have excellent performance that cannot be compared with existing device...

AI Technical Summary

Problems solved by technology

[0003] Existing GaN power devices mostly use Si 3 N 4 and SiO 2 The two materials are used as the cap layer of the device to form two structures of MISFET or MOSFET. However, since these two materials cannot be grown with GaN material once, but must be grown separately, the structure still has a high surface state. and defects, so that the leakage current of the device is high; at the same time, these two materials are mostly polycrystalline structures, resulting in poor withstand voltage characteristics of the device, which cannot give full play to the characteristics of high breakdown voltage of GaN materials, and it is difficult to further improve the power density of the device In addition, because the AlGaN layer of the existing planar structure GaN MISFET is usually doped with a high Al composition, there is a contradiction between the improvement of the Al composition and the manufacture of ohmic contacts, that is, in order to obtain a higher two-dimensional electron gas concentration, it is required Increase the Al composition, and in order to make a better ohmic contact, the Al composition should not be too high

Take the research of Arulkumaran et al. as an example, see Journal of Vacuum Science&Technology B: Microelectronics and NanometerStructures, March 2003, Volume21, Issue2, pp.888-894, the Al composition of the AlGaN layer is as high as 43%, and the ohmic contact of the device at this time It is difficult to manufacture, which seriously restricts the improvement of device performance

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