Hollow Electrode Enhanced RF Glow Plasma Generation and its Application to the Fast Deposition of Microcrystalline Silicon Films

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 the counter electrode, which includes a hollow structure and is placed between a RF electrode and the substrate. After introducing hydrogen gas into the chamber and applying RF power to the electrode, high intensity plasma emission is observed near and inside the hollow structure attached to the counter electrode. By using hollow RF electrode excitation in addition to the hollow counter electrode technique, it is found that plasma emission is further enhanced. The application of these discharge types for semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition (PECVD) of hydrogenated microcrystalline silicon thin films. High crystallinity, photo-sensitivity and a maximum deposition rate of 4.9nm/s can all be achieved at a plasma excitation frequency of 13.56MHz and a temperature of 300°C. Properties of these plasmas are investigated by observing the plasma emission pattern and optical emission spectrum analysis. It is found that, using additional hollow RF electrode discharge, faster processing of device grade hydrogenated microcrystalline silicon thin films can be achieved under lower RF power compared to hollow counter electrode technique alone.