A material etching system was developed by combining beam electron injection from a direct current hollow cathode (HC) electron source with the downstream reactive environment of a remote CF₄/O₂ low temperature plasma. The energy of the injected beam electrons is controlled using an acceleration electrode biased positively relative to the HC argon discharge. For an acceleration voltage greater than the ionization potential of Ar, the extracted primary electrons can produce a secondary plasma in the process chamber. The authors characterized the properties of the secondary plasma by performing Langmuir probe measurements of the electron energy probability function (EEPF) 2.5 cm below the extraction ring. The data indicate the existence of two major groups of electrons, including electrons with a primary beam electron energy that varies as the acceleration voltage is varied along with low energy electrons produced by ionization of the Ar gas atoms in the process chamber by the injected beam electrons. When combining the HC Ar beam electron with a remote CF₄/O₂ electron cyclotron wave resonance plasma, the EEPF of both the low energy plasma electron and beam electron components decreases. Additionally, the authors studied surface etching of Si₃N₄ and polycrystalline Si (poly-Si) thin films as a function of process parameters, including the acceleration voltage (0–70 V), discharge current of the HC discharge (1–2 A), pressure (2–100 mTorr), source to substrate distance (2.5–5 cm), and feed gas composition (with or without CF₄/O₂). The direction of the incident beam electrons was perpendicular to the surface. Si₃N₄ and polycrystalline silicon etching are seen and indicate an electron-neutral synergy effect. Little to no remote plasma spontaneous etching was observed for the conditions used in this study, and the etching is confined to the substrate area irradiated by the injected beam electrons. The electron etched Si₃N₄ surface etching rate profile distribution is confined within a ∼30 mm diameter circle, which is slightly broader than the area for which poly-Si etching is seen, and coincides closely with the spatial profile of beam electrons as determined by the Langmuir probe measurements. The magnitude of the poly-Si etching rate is by a factor of two times smaller than the Si₃N₄ etching rate. The authors discuss possible explanations of the data and the role of surface charging.

中文翻译：

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从空心阴极等离子体向下游反应环境中注入电子束：表征次级等离子体的产生以及Si3N4和Si蚀刻

通过将来自直流空心阴极（HC）电子源的束流电子注入与远程CF ₄ / O ₂的下游反应环境相结合，开发了一种材料蚀刻系统。低温等离子体。使用相对于HC氩气放电呈正偏的加速电极控制注入的电子束的能量。对于大于Ar的电离电势的加速电压，提取的一次电子可以在处理室中产生二次等离子体。作者通过对提取环下方2.5 cm处的电子能量概率函数（EEPF）进行Langmuir探针测量来表征次级等离子体的特性。数据表明存在两个主要的电子组，包括具有电子束电子能量的电子，该电子束电子随着加速电压的变化而变化，以及通过注入的电子束使处理室内的Ar气体原子电离而产生的低能电子。 。₄ / O ₂电子回旋波共振等离子体，低能等离子体电子和束电子的EEPF均降低。此外，作者研究了Si ₃ N ₄和多晶Si（poly-Si）薄膜的表面蚀刻与工艺参数的关系，这些工艺参数包括加速电压（0–70 V），HC放电的放电电流（1-2）。 A），压力（2–100 mTorr），源到基板的距离（2.5–5 cm）和进料气成分（有或没有CF ₄ / O ₂）。入射束电子的方向垂直于表面。硅₃ N ₄看到了多晶硅和多晶硅蚀刻，并表明了电子中性的协同效应。对于本研究中使用的条件，几乎没有观察到远程等离子体自发蚀刻，并且蚀刻限于注入的电子束辐照的基板区域。电子刻蚀的Si ₃ N ₄表面刻蚀速率分布分布被限制在直径约30 mm的圆内，该范围略宽于可以看到的多晶硅刻蚀区域，并且与所确定的电子束的空间分布非常吻合由Langmuir探针测量。多晶硅蚀刻速率的大小是Si ₃ N _4的两倍小蚀刻速率。作者讨论了有关数据和表面电荷作用的可能解释。