During the last few years and with the commercialization of the gallium nitride based high electron mobility transistor, research effort on gallium nitride has been strongly increasing. Besides activities regarding lateral devices like the gallium nitride high electron mobility transistor, progress in the growth of native gallium nitride substrates encourages the development of vertical devices. In particular, for power electronics above 600 V, vertical architecture shows superior performance compared to lateral devices. This makes the vertical approach interesting for the use in traction inverters in the rising market of e-mobility. A key aspect in the fabrication of most vertical devices is the formation and optimization of trenches in the semiconductor. In this work, the fabrication of 1.5–$2\mu \mathrm{m}$ deep, crystal plane oriented trenches in gallium nitride with lateral dimension as small as $1\mu \mathrm{m}$ is demonstrated. The trenches were produced by means of plasma etching based on sulfur hexafluoride and argon as well as a subsequent wet etching step in tetramethylammonium hydroxide and potassium hydroxide. By accurately aligning the trenches along the $\left[\overline{1}010\right]$- and $\left[1\overline{2}10\right]$-directions, the authors were able to evaluate the wet etching behavior of the respective crystal planes and achieved smooth vertical sidewalls.

中文翻译：

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使用SF6 + Ar干法刻蚀和湿法刻蚀后处理在氮化镓中制造晶面定向沟槽

在过去的几年中，并且随着基于氮化镓的高电子迁移率晶体管的商业化，对氮化镓的研究工作一直在大力增加。除了与诸如氮化镓高电子迁移率晶体管之类的横向器件有关的活动之外，天然氮化镓衬底生长的进步也促进了垂直器件的发展。特别是，对于600 V以上的功率电子设备，垂直结构比横向设备具有更高的性能。这使得垂直方法对于在不断增长的电动汽车市场中的牵引逆变器中的使用很有趣。大多数垂直器件制造中的一个关键方面是半导体中沟槽的形成和优化。在这项工作中，制作1.5 –$2\mu \mathrm{米}$ 氮化镓中晶面取向的深沟槽，横向尺寸小至 $\mathrm{1个}\mu \mathrm{米}$被证明。通过基于六氟化硫和氩气的等离子体蚀刻以及随后的在氢氧化四甲铵和氢氧化钾中的湿法蚀刻步骤来产生沟槽。通过沿沟槽精确对准沟槽$\left[\overline{\mathrm{1个}}010\right]$-和 $\left[\mathrm{1个}\overline{2}10\right]$方向，作者能够评估各个晶面的湿法刻蚀行为，并获得了光滑的垂直侧壁。