Method for preparing normally-off HEMT device through novel heterostructure magnesium diffusion

Abstract

The invention discloses a method for preparing a normally-off HEMT device through novel heterostructure magnesium diffusion. The method comprises the following steps: growing an AlN material on the Si-based GaN epitaxial wafer through an atomic layer deposition technology; performing photoetching to prepare a gate window, depositing magnesium metal in a gate region by adopting a thermal evaporation and stripping process, carrying out thermal annealing to realize p-type doping of an AlN material, carrying out surface magnesium oxidation in an air atmosphere to realize a magnesium oxide passivation layer, and preparing a source electrode, a drain electrode and a gate electrode to obtain the normally-closed HEMT device. According to the method, the magnesium diffusion AlN / GaN heterostructureis novel, AlN is used as a barrier layer, the concentration of two-dimensional electron gas is increased, the saturation current of a device is increased, p-type doping of an AlN material is achieved,and the problem that a high-Al-component compound semiconductor is difficult to dope is solved. The method is a novel method for realizing the normally-off HEMT device through heterostructure doping,and has important significance for realizing the high-performance normally-off HEMT device.

Description

technical field [0001] The invention belongs to the technical field of semiconductor devices, and in particular relates to a method for preparing a normally-off HEMT device by diffusion of magnesium with a novel heterogeneous structure. Background technique [0002] With the continuous application and development of power radio frequency devices, normally-off HEMT devices have become a research hotspot in this field. [0003] At present, the mainstream normally-off device heterostructure is mainly AlGaN / GaN. At the same time, there are very few studies on the p-type thermal doping of AlGaN materials in this heterostructure. At present, only a few have realized the p-type thermal diffusion doping of AlGaN materials. , but it has a greater impact on the saturation current, resulting in a lower saturation output current, which in turn affects the overall performance of the device. [0004] CN109888013A discloses an enhanced GaN-based HEMT device prepared by doping magnesium an...

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Problems solved by technology

[0003] At present, the mainstream normally-off device heterostructure is mainly AlGaN / GaN. At the same time, there are very few studies on the p-type thermal doping of AlGaN materials in this heterostructure. At present, only a few have realized the p-type thermal diffusion doping of AlGaN materials. , but it has a greater impact on the saturation current, resulting in a lower saturation output current, which in turn affects the overall performance of the device

[0004] CN109888013A discloses an enhanced GaN-based HEMT device prepared by doping magnesium and its preparation method, but in this thermal diffusion method, the general AlGaN / GaN heterostructure is only doped, and for AlN with higher Al composition There is almost no material doping, and the needs for normally-off HEMT devices that achieve large saturated output currents cannot be well met

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