The effects of process conditions on the plasma characteristic in radio-frequency capacitively coupled SiH₄/NH₃/N₂ plasmas: Two-dimensional simulations

A two-dimensional (2D) fluid model is presented to study the behavior of silicon plasma mixed with SiH₄, N₂, and NH₃ in radio-frequency capacitively coupled plasma (CCP) reactor. The plasma-wall interaction (including the deposition) is modeled by using surface reaction coefficients. In the present paper we try to identify, by numerical simulations, the effect of variations of the process parameters on the plasma properties. It is found from our simulations that by increasing the gas pressure and the discharge gap, the electron density profile shape changes continuously from an edge-high to a center-high, thus the thin films become more uniform. Moreover, as the N₂/NH₃ ratio increases from 6/13 to 10/9, the hydrogen content can be significantly decreased, without decreasing significantly the electron density.