阅读说明：本技术 纳米孔栅极掺杂制备的常关型hemt器件及制备方法 (Normally-off HEMT device prepared by doping nano-hole gate and preparation method ) 是由 李国强 万利军 孙佩椰 阙显沣 姚书南 于 2019-11-13 设计创作，主要内容包括：本发明公开了一种纳米孔栅极掺杂制备的常关型HEMT器件及制备方法,所述器件包括从下到上依次排布的硅衬底、GaN外延层和AlGaN势垒层,AlGaN势垒层上表面具有纳米孔栅结构,纳米孔栅结构掺杂有金属镁,形成p型AlGaN层,AlGaN势垒层上表面的两端接触有源极和漏极,p型AlGaN层的上表面接触有栅极。本发明利用感应耦合等离子体刻蚀机(ICP)对光刻制备的纳米栅电极接触窗口区域进行刻蚀处理形成纳米栅结构,通过掺杂来实现常关型GaN HEMT器件。该制备方法对于抑制电流衰减,实现大饱和电流常关型GaN HEMT器件有重要意义。(The invention discloses a normally-closed HEMT device prepared by doping a nanopore gate and a preparation method thereof. The method utilizes an inductively coupled plasma etcher (ICP) to etch a contact window area of the nano gate electrode prepared by photoetching to form a nano gate structure, and realizes the normally-off GaN HEMT device by doping. The preparation method has important significance for restraining current attenuation and realizing the large saturation current normally-off GaN HEMT device.)

1. The normally-closed HEMT device prepared by doping the nanopore gate is characterized by comprising a silicon substrate, a GaN epitaxial layer and an AlGaN barrier layer which are sequentially arranged from bottom to top, wherein the upper surface of the AlGaN barrier layer is provided with a nanopore gate structure, the nanopore gate structure is doped with metal magnesium to form a p-type AlGaN layer, two ends of the upper surface of the AlGaN barrier layer are contacted with a source electrode and a drain electrode, and the upper surface of the p-type AlGaN layer is contacted with a gate electrode.

2. A method of fabricating the normally-off HEMT device of claim 1 by nanoporous gate doping comprising the steps of:

(1) photoetching the AlGaN barrier layer to prepare a nano-pore gate electrode photoetching contact window area to obtain a device containing the nano-pore gate electrode photoetching contact window;

(2) etching the nano-pore gate electrode photoetching contact window area in the step (1) to prepare an etched nano-pore contact window area, and obtaining an etched device;

(3) evaporating metal magnesium in the etched nano-hole contact window area to obtain a device containing metal magnesium;

(4) stripping the unexposed photoresist on the device containing the metal and the magnesium in the step (3) to obtain a stripped device;

(5) carrying out thermal doping treatment on the device subjected to the stripping treatment in the step (4) to prepare a P-type AlGaN doping layer so as to obtain the device subjected to the thermal doping treatment;

(6) and (5) photoetching an AlGaN barrier layer in the device subjected to the thermal doping treatment in the step (5), and then preparing a source electrode, a drain electrode and a gate electrode to obtain the normally-off GaN HEMT device prepared by doping the nanopore gate electrode.

3. The method for preparing a normally-off HEMT device by doping the nanopore gate according to claim 2, wherein the etching in the step (2) is ICP etching.

4. The method for preparing a normally-off HEMT device by doping the nanopore gate according to claim 2, wherein the etching time in the step (2) is 3-20 s.

5. The method for preparing a normally-off HEMT device by nanopore gate doping according to claim 2, wherein said magnesium metal of step (3) has a thickness of 10-50 nm.

6. The method for preparing a normally-off HEMT device according to claim 2, wherein said evaporation in step (3) comprises electron beam evaporation.

7. The method for preparing a normally-off HEMT device according to claim 2, wherein the temperature of the thermal doping in step (5) is 200-1000 ℃.

8. The method for preparing a normally-off HEMT device according to claim 2, wherein the thermal doping in step (5) is performed for a time of 0.5-100 min.

Technical Field

The invention belongs to the technical field of semiconductor devices, and particularly relates to a normally-off HEMT device prepared by doping a nanopore gate and a preparation method thereof.

Background

In the fields of microwave power amplifiers and low-noise power amplifiers, the normally-off HEMT device does not need negative voltage control, so that the complexity and the cost of a circuit are greatly reduced. The market is also favored in the field of high power switches by virtue of their circuit safety.

The most mature method in the current method for preparing the normally-off HEMT device is mainly realized by reducing the thickness of the barrier layer, wherein the thickness of the barrier layer right below the grid is mainly reduced, the polarization effect at the position can be further weakened by reducing the thickness of the barrier layer below the grid, and the concentration of two-dimensional electron gas is reduced to enable the device to reach the off state. The method can improve the high-frequency performance of the HEMT device and reduce the short-channel effect of the device. However, the method has high requirements on etching precision, and poor stability and repeatability of the process, so that the controllability of the threshold voltage of the device is poor, and in addition, the performance of the device is seriously influenced by the damage caused by etching, so that serious grid leakage and low saturation current are caused.

CN109888013A discloses a magnesium-doped enhanced GaN-based HEMT device and a preparation method thereof, but the method still has the problem that the doping concentration is too high and too deep to cause the damage of channel two-dimensional electron gas, thereby influencing the saturation current of the device and causing the obvious reduction of the saturation current.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a normally-off HEMT device prepared by doping a nano-hole grid and a preparation method thereof. Etching the surface of the AlGaN barrier layer in the etched nanopore gate region by ICP (inductively coupled plasma) to form a nanopore gate structure, and annealing magnesium under a high-temperature condition by filling metal magnesium in a subsequent nanopore to realize magnesium diffusion to form p-type doping of an AlGaN material, thereby finally realizing the preparation of a normally-off HEMT (high Electron mobility transistor) device.

The invention provides a normally-closed HEMT device prepared by doping a nanopore gate, which comprises a silicon substrate, a GaN epitaxial layer and an AlGaN barrier layer which are sequentially arranged from bottom to top, wherein the upper surface of the AlGaN barrier layer is provided with a nanopore gate structure, the nanopore gate structure is doped with metal magnesium to form a p-type AlGaN layer, two ends of the upper surface of the AlGaN barrier layer are contacted with a source electrode and a drain electrode, and the upper surface of the p-type AlGaN layer is contacted with a gate electrode.

The invention also provides a method for preparing the normally-off HEMT device by doping the nano-hole grid, which comprises the following steps:

(1) photoetching the AlGaN barrier layer to prepare a nano-pore gate electrode photoetching contact window area to obtain a device containing the nano-pore gate electrode photoetching contact window;

(2) etching the nano-pore gate electrode photoetching contact window area in the step (1) to prepare an etched nano-pore contact window area, and obtaining an etched device;

(3) evaporating metal magnesium in the etched nano-hole contact window area to obtain a device containing metal magnesium;

(4) stripping the unexposed photoresist on the device containing the metal and the magnesium in the step (3) to obtain a stripped device;

(5) carrying out thermal doping treatment on the device subjected to the stripping treatment in the step (4) to prepare a P-type AlGaN doping layer so as to obtain the device subjected to the thermal doping treatment;

(6) and (5) photoetching an AlGaN barrier layer in the doped device in the step (5), and then preparing a source electrode, a drain electrode and a gate electrode to obtain the normally-off GaN HEMT device prepared by doping the nanopore gate.

Preferably, the etching in the step (2) is ICP etching.

Preferably, the etching time of the step (2) is 3-20 s.

Preferably, the thickness of the metal magnesium in the step (3) is 10-50 nm.

Preferably, the evaporation manner in step (3) includes electron beam evaporation.

Preferably, the temperature of the thermal doping in the step (5) is 200-1000 ℃.

Preferably, the time for thermal doping in step (5) is 0.5-100 min.

Compared with the prior art, the invention has the following beneficial effects and advantages:

the method utilizes an inductively coupled plasma etcher (ICP) to carry out etching treatment on the surface of the AlGaN barrier layer in the etching nanopore gate region to form a nanopore gate structure, and realizes the normally-off HEMT device by thermal doping of metal magnesium. The preparation method provided has important significance for inhibiting current attenuation and realizing a large saturation current normally-off GaN HEMT device.

Drawings

Fig. 1 is a schematic structural diagram of a normally-off HEMT device prepared by doping a nanopore gate according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for manufacturing a normally-off HEMT device by nanopore gate doping according to the present invention;

FIG. 3 is a device transfer curve test chart provided in example 1 of the present invention;

in the figure: 1-a silicon substrate; 2-GaN epitaxial layer; a 3-AlGaN barrier layer; 4-photoresist; 5-metallic magnesium; a 6-p type AlGaN layer; a 7-source electrode; 8-a drain electrode; 9-grid electrode.

Detailed Description

The following description of the embodiments of the present invention is provided in connection with the accompanying drawings and examples, but the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art.