Estimations of secondary electron emission coefficients of Si, SiO₂, and polyimide electrodes in dual-frequency capacitively coupled discharge

Abstract

In a dual-frequency capacitively coupled Ar plasma, the secondary electron emission (SSE) coefficients were estimated using 2D fluid model and experiments. The electron density was measured in the plasma chamber with the upper and lower electrodes of Si. The electron density was calculated by changing the SEE coefficient. The SEE coefficient of the Si electrode was estimated to be 0.06 so that the electron density of the 2D fluid model was close to that of the experimental result. Next, the electron density was measured in the chamber of the lower electrode covered with SiO2 and polyimide and the SEE coefficients were estimated by comparing experiments and 2D fluid model. The SEE coefficients of the SiO2 and the polyimide were estimated to be 0.24 and 0.22, respectively. Moreover, The SEE coefficients of SiO2 was almost the same in the range between 300 and 500 W of the lower electrode power.

Comparison of distributions of etching rate and calculated plasma parameters in dual-frequency capacitively coupled plasma

“…The CF 4 molecular also reacts with the solid surface and disappears, but the CF 4 density in the chamber was kept constant by setting the CF 4 gas pressure constant. [19][20][21]…”

“…We evaluated the secondary electron emission coefficient by simulations of dual-frequency excited plasmas. [19][20][21] In this paper, the in-plane distribution of Si and SiO 2 etching rates, and the distributions of the radical species densities in the plasma were compared. The etching rates of both Si and SiO 2 increased around the wafer edge, and the Si etching rate was distributed uniformly without the power supply of the lower electrode (bias voltage).…”