Hollow electrode enhanced RF glow plasma for the fast deposition of microcrystalline silicon

Abstract

A hollow electrode enhanced RF glow plasma excitation technique has been newly developed. In this technique, the reactor is divided into a capacitively-coupled RF glow discharge space and a processing space by counter electrode, which has a hollow structure and is placed between RF electrode and substrate. Hollow electrode discharge is induced inside this hollow structure. The application of this discharge type for semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition of hydrogenated microcrystalline silicon (μc-Si) thin films. It is found that high crystallinity, photo sensitivity and maximum deposition rate of 4.9 nm/s can be achieved at the plasma excitation frequency of 13.56 MHz. Properties of this plasma are investigated by observation of the plasma emission pattern viewed through the window, optical emission spectral analysis and the plasma potential. Plasmas generated inside the new apparatus is compared to those of normal capacitively-coupled RF plasmas. In our apparatus, high intensity plasma emission is observed near and inside the hollow structure attached to the counter electrode. The spectral and plasma potential analysis showed that both the intensity of SiH* and the plasma potential of our plasma are higher than that of normal capacitively-coupled plasma.