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Poster Session I

4:30 pm – 6:30 pm, Tuesday October 14 Session DT4 COEX, Lobby E
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Experimental Characterization of Plasma Instabilities in Moderate-Pressure Capacitively Coupled Plasmas Using Laser-Collision Induced Fluorescence

Poster 83
Presenter: Brian Z Bentz (Sandia National Laboratories)
Authors: Omar Alsaeed (North Carolina State University), Cameron Wagoner (North Carolina State University), Amanda Lietz (North Carolina State University)

Self-organization in radiofrequency plasmas remains a persistent challenge for achieving spatially uniform processing in semiconductor manufacturing. This work presents an experimental investigation of spatiotemporal instabilities in symmetric, planar capacitively coupled plasmas (CCPs) operated at moderate pressures (0.1–10 Torr) in electropositive gases (He, Ar, N₂). Using laser-collision induced fluorescence (LCIF) and phase-resolved optical emission spectroscopy (PROES), we measure the electron density and temporal growth rates of emergent unstable modes. The diagnostics provide complementary views into the electron dynamics that lead to pattern formation. We compare our measurements to recent theoretical predictions based on a fluid electron model incorporating thermoelectric energy transport, with a focus on assessing the stability boundary and dynamics as a function of discharge gap, gas pressure, and chemistry. The results reveal trends consistent with the predicted dependence of instability on transport coefficients and support ongoing efforts to determine the dominant mechanisms responsible for self-organization in CCPs and inductively coupled plasmas (ICPs). These measurements also provide important validation data for modeling efforts aimed at predictive control of plasma uniformity in industrial systems.

Funding acknowledgement

Work supported by Lam Research Corporation, U.S. DOE Early Career Research Program Award DE-SC0025621, and by Sandia National Laboratories' Plasma Research Facility, funded by the U.S. Department of Energy Office of Fusion Energy Sciences. Sandia is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

POSTERS (97)