Our interest in introducing oxygen and/or nitrogen atoms in CH₄/H₂/Ar plasma mixtures by means of organic precursors in the place of CH₄ or by partly substituting O₂ or N₂O for H₂ and thereby controlling carbon deposition and surface passivation when etching HgCdTe under low substrate bias conditions is investigated in this study. Using in situ ellipsometry, in situ x-ray photoelectron spectroscopy, atomic force microscopy, and secondary electron microscopy (SEM), we show that nitromethane as a precursor and N₂O substitution are attractive alternatives for the following: the absence of deposition although no bias is applied, equivalent postetch surface composition, and comparable performances in terms of etch rate and surface roughness for the latter. Such an approach could provide the soft dry etching conditions needed to reduce the pixel pitch of HgCdTe infrared photovoltaic detectors. The mechanisms that allow suppressing carbon deposition upon O₂ or N₂O substitution in CH₄/H₂/Ar plasmas are studied by combining plasma diagnostics (optical emission spectroscopy, actinometry, and ion flux measurements) and surface characterizations. First, using Si as a reference substrate, it is shown that deposition is suppressed whenever the O₂ and N₂O flow rate is half and twice that of CH₄, respectively. Moreover, the study reveals that oxygen is the true etch reactant controlling the competition between film growth and etching in both substituted processes, whereas incorporation of nitrogen in the film upon N₂O substitution favors its etching kinetics simultaneously. Second, on HgCdTe, deposition of a hydrocarbonitride film is observed at a low N₂O/CH₄ ratio (∼0.6). SEM and SEM-energy dispersive x-ray spectroscopy imaging suggest that the film nucleates and grows preferentially on regions where the Cd removal mechanisms happen to be less efficient. At a high N₂O/CH₄ ratio (∼4), oxidation of the HgCdTe surface is observed.

中文翻译：

---

研究有机前体和等离子体混合物可在碳氢基感应耦合等离子体中蚀刻HgCdTe时控制碳钝化

我们的兴趣是通过有机前驱物代替CH ₄或通过用O ₂或N ₂ O部分代替H ₂从而在CH ₄ / H ₂ / Ar等离子体混合物中引入氧和/或氮原子，从而控制碳沉积和本研究研究了在低衬底偏置条件下蚀刻HgCdTe时的表面钝化。使用原位椭偏仪，原位X射线光电子能谱，原子力显微镜和二次电子显微镜（SEM），我们显示了硝基甲烷作为前体和N ₂O替代是用于以下方面的有吸引力的替代方案：尽管没有施加偏压但没有沉积，等同的蚀刻后表面组成以及就后者的蚀刻速率和表面粗糙度而言可比的性能。这种方法可以提供减少HgCdTe红外光电探测器像素间距所需的软干蚀刻条件。通过结合等离子体诊断（光学发射光谱，光化法和离子通量测量）和表面表征，研究了在CH ₄ / H ₂ / Ar等离子体中抑制O ₂或N ₂ O取代时碳沉积的机理。首先，使用Si作为参考衬底，表明每当O被抑制时，沉积被抑制。₂和N ₂ O的流速分别是CH _4的一半和两倍。此外，研究表明，氧是控制两种生长过程中膜生长与腐蚀之间竞争的真正腐蚀反应物，而氮在N ₂ O置换后在膜中的掺入同时有利于其腐蚀动力学。其次，在HgCdTe上，以低N ₂ O / CH ₄比（〜0.6）观察到碳氮化物膜的沉积。SEM和SEM能量色散X射线光谱成像表明，该膜在Cd去除机理效率较低的区域优先成核并生长。高N ₂ O / CH ₄ 比率（〜4），观察到HgCdTe表面的氧化。