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Comparison of plasma properties in normal and multiple holes hollow cathode RF PECVD and their utility in a-SiNx:H thin film deposition
摘要： Conventional and multiple-hole hollow cathode (MHHC) showerhead electrodes of an RF capacitively coupled plasma (CCP) source were experimentally studied to investigate their capability of plasma generation and suitability of plasma application like PECVD. The plasma characteristics of the CCPs were critically examined for the PECVD plasmas produced by various showerhead configurations. The optimum performance in terms of high-density plasma generation and high emission intensity of excited species was observed for the operation using MHHC discharge. The MHHC discharge is characterized by an anode glow and a strong low-frequency fluctuation in the range of ~ a few kHz that is measured by the Langmuir probe (LP). The LP measurements in a broad pressure range revealed the scenario of hollow cathode discharge characterized by the enhanced electron temperature and the highest plasma density around 120 mTorr. It is realized that the bulk plasma intrusion inside the hole of the electrodes of the showerhead and the enhanced ionization in the plasma sheath regions of each hole facilitated the generation of high-density plasmas when the hole diameter is slightly bigger than twice or thrice the sheath length. The effectiveness of MHHC PECVD for high rate and low-temperature deposition of a-SiNx:H thin films is realized.
关键词： Hollow cathode discharge,Plasma instability,Silicon nitride film,RF Plasma source
更新于2025-09-10 09:29:36
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Investigation of moments-based transport models applied to plasma waves and the Dyakonov–Shur instability
摘要： Transport models based on balance equations with different degrees of numerical complexity can be derived from the Boltzmann transport equation (BTE). In this paper two different drift-diffusion models based on the first two moments of the BTE as well as two hydrodynamic models based on four moments are derived and analyzed for their accuracy in the THz frequency range with emphasis on the generation of plasma waves. To this end, they are compared to the BTE in the small-signal regime under homogeneous bulk conditions where harmonic waves were assumed, which reveals that the hydrodynamic models provide a higher accuracy. It is also shown that the anisotropy of the distribution function must be taken into account in the closure relations. This leads to convective derivatives in the balance equations, which are very difficult to treat by numerical means in the case of semiconductor devices and are neglected in commercial TCAD suites. But without them a meaningful simulation of the Dyakonov–Shur plasma instability will not be possible.
关键词： Boltzmann transport equation,THz,drift-diffusion,plasma instability,hydrodynamic
更新于2025-09-04 15:30:14