System and method for self-stopping recessed gate-enhanced hemt devices by photo-assisted etching

Abstract

The invention discloses a method for achieving a concave grating-enhanced HEMT device through photo-assisted etching self-stopping. The method comprises the steps as follows: an etched sample is provided; a patterned mask is arranged on the surface of the etched sample to expose an etched surface; the etched surface of the etched sample is directly exposed in an etching solution and the etched surface is at least irradiated by an etching ray, so that the etching solution etches the etched sample on the etched surface, and meanwhile, an etched product which can stably exist in the etching solution is formed; and when a groove structure corresponding to a required concave gating structure is etched on the etched sample, the generated etched product is enough to passivate the etched surface for etching self-stopping. According to the method, an enhanced HEMT can be effectively achieved, the method has the characteristics of being simple in process, high in repeatability, small in etching damage, simple in equipment and low in cost, the etching self-stopping is carried out and massive production is easy to implement.

Description

technical field [0001] The invention relates to an enhanced HEMT device, in particular to a method for realizing a concave grid enhanced HEMT device by self-stopping of photo-assisted etching. Background technique [0002] HEMT devices are made by making full use of the two-dimensional electron gas formed by the heterojunction structure of semiconductors. Compared with III-VI (such as AlGaAs / GaAs HEMT devices), III-nitride semiconductors are due to piezoelectric polarization and spontaneous Due to the polarization effect, a high-concentration two-dimensional electron gas can be formed on a heterostructure (such as AlGaN / GaN). Therefore, in HEMT devices made of group III nitrides, the barrier layer generally does not need to be doped. Group III nitrides have the characteristics of large band gap, high saturated electron drift velocity, high critical breakdown electric field and strong radiation resistance, which can meet the requirements of higher power and higher power devi...

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Problems solved by technology

For example, the world's first enhancement mode HEMT device is realized by using a thinner barrier layer. This method does not use an etching process, so the damage caused is small, but due to the thinner barrier layer, the saturation of the device The current is small; the P-type capping layer does not require an etching process, but a more serious interface state is generated, which affects the stability of the device; F plasma treatment can also realize an enhanced HEMT device, and does not require etching, but the F plasma The barrier layer is also etched during the implantation process, resulting in a decrease in device performance

In the formation process of the existing concave gate structure, the barrier layer under the gate is mainly realized by plasma (mainly chlorine-based plasma) etching method, and the barrier layer of a general HEMT device is only 20-30nm. Therefore, the etching of the concave gate still faces problems such as the control of the etching thickness and the repair of the etching damage. The process of forming the concave grid structure by the etching process is difficult to control and the repeatability is poor.

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