The addition of CHF3 to Cl2/Ar inductively coupled plasmas operating at low dc self-biases (<100 V, corresponding to incident ion energies <125 eV) leads to etch selectivity for Ga2O3 over (Al0.18Ga0.82)2O3 of >30, with a maximum value of 55. By sharp contrast, without CHF3, the etching is nonselective over a large range of source and rf chuck powers. We focused on low ion energy conditions that would be required for device fabrication. This result has a direct application to selective removal of Ga2O3 contact layers to expose underlying (Al0.18Ga0.82)2O3 donor layers in high-electron-mobility transistor structures. It is expected that formation of nonvolatile AlF3 species helps produce this selectivity. X-ray photoelectron spectroscopy does detect F residues on the etched surface for the Cl2/Ar/ CHF3 plasma chemistry.

中文翻译：

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(Al0.18Ga0.82)2O3/ Ga2O3 异质结构的选择性和非选择性等离子体蚀刻

将 CHF3 添加到在低直流自偏压（<100V，对应于入射离子能量<125eV）下运行的 Cl2/Ar 电感耦合等离子体中，导致 Ga2O3 的蚀刻选择性超过 (Al0.18Ga0.82)2O3 ＞30，最大值为55。形成鲜明对比的是，在没有CHF 3 的情况下，蚀刻在大范围的源和射频卡盘功率上是非选择性的。我们专注于器件制造所需的低离子能量条件。该结果可直接应用于选择性去除 Ga2O3 接触层，以暴露高电子迁移率晶体管结构中下面的 (Al0.18Ga0.82)2O3 施主层。预计非挥发性 AlF3 物质的形成有助于产生这种选择性。X 射线光电子能谱确实可以检测 Cl2/Ar/CHF3 等离子体化学蚀刻表面上的 F 残留物。