Abstract Full recess architecture for GaN based High Electron Mobility Transistor (HEMT) enables high mobility and high density of electrons to be conserved without compromising on voltage threshold. To obtain such architecture, standard RIE plasma etching processes are not suitable due to electrical degradation effects and to the lack of well controlled etch depth. To address these limitations, several Atomic Layer Etching (ALE) processes have been developed in the past. In this work, we study an atomic layer etching (ALE) of GaN based on cyclic steps composed of O2 plasma followed by BCl3 plasma. XPS analysis of the GaN's top surface after each step of the O2-BCl3 process enabled to propose an etching mechanism and to track nitrogen depletion. The cyclic process conserves the surface stoichiometry. Finally, this cyclic process has been validated on patterns, showing a good morphology, a good etch depth control and a slightly lower electrical degradation compared to standard RIE process.

中文翻译：

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使用自限循环方法对功率器件应用进行选择性 GaN 蚀刻工艺的 XPS 研究

摘要 基于 GaN 的高电子迁移率晶体管 (HEMT) 的全凹陷结构能够在不影响电压阈值的情况下保存高迁移率和高密度的电子。为了获得这样的结构，标准的 RIE 等离子体蚀刻工艺由于电退化效应和缺乏良好控制的蚀刻深度而不适合。为了解决这些限制，过去已经开发了几种原子层蚀刻 (ALE) 工艺。在这项工作中，我们研究了基于由 O2 等离子体和 BCl3 等离子体组成的循环步骤的 GaN 原子层蚀刻 (ALE)。在 O2-BCl3 工艺的每个步骤之后，对 GaN 顶部表面的 XPS 分析能够提出蚀刻机制并跟踪氮消耗。循环过程保留了表面化学计量。最后，