Study of dry etched N-polar (Al)GaN surfaces obtained by inductively coupled plasma etching
Study of dry etched N-polar (Al)GaN surfaces obtained by inductively coupled plasma etching
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DOI：
10.3389/fphy.2022.1042998
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
X. Ge;Xue-Jie Yin;Qiaoyu Zeng;Qiquan Feng;Xiaohui Wang;Quantong Li;Zhitao Chen;Chengguo Li
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文献类型：
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作者：
X. Ge;Xue-Jie Yin;Qiaoyu Zeng;Qiquan Feng;Xiaohui Wang;Quantong Li;Zhitao Chen;Chengguo Li
我们报道了基于Cl的电感耦合等离子体刻蚀N-极性Al（Ga）N层从层转移。发现蚀刻后的N极表面在空气中暴露短时间后出现碎片，而蚀刻后的Al/Ga极表面干净光滑。在空气中暴露几个小时后，碎片可以在N-极性Al 0.4Ga 0.6N表面上完全自行消失，但即使在1个月后仍然保留在N-极性GaN表面上。表面化学分析结果表明，碎片是在蚀刻过程中产生的Cl相关的副产物的结果。在电感耦合等离子体刻蚀后，副产物Al（Ga）Clx及其衍生物被认为覆盖在N极性表面上，并显著增加了刻蚀表面的粗糙度。碎片的形成和消失分别归因于Al（Ga）Clx在空气中吸收水分时形成的Al（Ga）Clx·6 H2O晶体和其在N极性表面上的自发分解。在工艺中添加O2/SF6有助于去除Al（Ga）Clx副产物，但代价是表面粗糙化/蚀刻速率降低。在合理的刻蚀速率（≤ 150 nm/min）下，通过刻蚀后的附加清洗工艺，成功地获得了均匀、光滑的N极性GaN表面，其均方根表面粗糙度为0.5-0.6 nm。研究结果可为高性能N极性GaN器件的制备提供有价值的指导。
We report the Cl-based inductively coupled plasma etching of N-polar Al(Ga)N layers obtained from layer transfer. It is found that debris appeared on the etched N-polar surface after exposing in air for a short period whereas the etched Al-/Ga-polar surface was clean and smooth. The debris can be completely self-vanished on the N-polar Al0.4Ga0.6N surface after exposing in air for a few hours but still remained on the N-polar GaN surface even after over 1 month. The surface chemical analysis results suggested that the debris is the result of Cl-related byproduct generated during the etching process. Byproducts like Al(Ga)Clx and its derivatives are believed to cover on the N-polar surface after the inductively coupled plasma etching and increase the etched surface roughness significantly. The formation and disappearance of debris are attributed to the formation of Al(Ga)Clx⋅ 6H2O crystals when Al(Ga)Clx absorbs moisture in the air and its spontaneous decomposition on the N-polar surface, respectively. Adding O2/SF6 in the process helps remove Al(Ga)Clx byproducts but at the cost of roughened surface/reduced etch rate. With an additional cleaning process after etching, an uniform and smooth N-polar GaN surface with a low root-mean-square surface roughness of 0.5–0.6 nm has been successfully obtained at a reasonable etch rate (∼150 nm/min). The results can provide valuable guidance for the fabrication of high-performance N-polar GaN devices.