A. Rawat, R. Awadhani, S. Knott, T. Gilmore, Impedans Ltd, Ireland
The key process drivers in the majority of plasma processes are the ion flux and energy distribution arriving at the wafer substrate. This work reports the direct measurements of ion flux and energy distribution at the wafer position, using a fully automated advanced Retarding Field Energy Analyzer (RFEA), thereby providing deep insight into what happens at the wafer surfaces. These RFEAs accurately measure the uniformity of ion energies and ion flux hitting a surface, time-resolved ion beams, and bias voltage at any position inside a plasma chamber using an array of integrated sensors. Measurements reported highlights the crucial role of energetic ions in plasmas and how they affect the properties of materials deposited in thin-film plasma processing. Sensor application in various commercial plasma tools is presented across a broad range of plasma processing conditions. Particular emphasis is given to plasma-assisted Atomic Layer Deposition (ALD) and Atomic Layer Etching (ALE) processes. Some of the major contributions include discussion on the impact of substrate biasing on the ion energy distribution (IED), impact of ion impingement on the chemical and microstructural properties of thin-films, detection of positive and negative ion beams, effect of plasma gas, chamber pressure, bias power etc.