The role of gas phase reactions, electron impact, and collisional energy transfer processes relevant to plasma etching of polysilicon with H2 and Cl2

Abstract

Plasma etching of silicon with H2 and Cl2 was simulated with mixtures of H2, Cl2, and SiCl4. The gas phase chemistry was elucidated by varying power and pressure. The cross sections for production of H (3p2P) atoms were probed through the emission response to pressure variations. Addition of rare gases to a hydrogen plasma identified qualitatively major energy transfer paths between the rare gas metastables and the H2/H system. We conclude that dissociation of hydrogen molecules and excitation of hydrogen atoms are separate electron impact collisional events that constitute the main excitation route in a hydrogen plasma. We find further that the role of metastable H atoms in the 2s2S state at 10.19 eV is minor, and that the direct dissociative excitation in a single electron impact at 16.57 eV is insignificant. The occurrence of state specific collisional energy exchange has limiting consequences for any actinometric method.

Effects of Chlorine on Aluminum Refining: A Review and an <i>Ab Initio</i> Molecular Dynamics Study

“…It has been found that the purge gas mixed with little chlorine gas is much more effective than pure ones [11,12]. Although hydrogen can be removed from aluminum melts by such techniques, the understanding of hydrogen solubility and diffusion is far from enough [13], and mechanism that chlorine gas used in degassing for complete hydrogen removal is still on considerable debate [12].…”

Determination of atomic hydrogen density in non-thermal hydrogen plasmas via emission actinometry

“…It is reasonable to neglect the two-step excitation process for the excitation of Ar (4p) via metastable Ar (4s) [19]. The predictive cascades and contribution of metastable H (2s) atoms to the production of H (n = 3) are both negligible.…”

Plasma Triggered Grain Coalescence for Self-Assembly of 3D Nanostructures

“…Plasma surface reaction, which enables controllable heat generation, is one of the approaches for triggering grain coalescence and controlling the coalescence performance [14–16]. Specifically, numerous plasma etching systems exhibit localized heat generation in the area of plasma/surface interaction [17–22]. The plasmochemical reactions in these plasma etching systems are exothermic and able to thermally stimulate a wide range of physical processes and chemical reactions [21, 22].…”