Distributed elementary ECR microwave plasma sources supplied by solid state generators for production of large area plasmas without scale limitation: Plasma density measurements and comparison with simulation

Abstract

High-density reactive species plasmas uniformly covering large surface areas are required for semiconductor processing. Novel, self-matched plasma sources using microwave solid state generators have been developed for this purpose. The technology applied, based on automatic frequency tuning, allowed to eliminate the impedance matching system. Large surface plasmas have been achieved by using a distribution of elementary sources. Abig campaign of plasma density measurement using a Langmuir probe has allowed to create a database for different plasma conditions for a single source. Thanks to an internally developed software, the density obtained with several sources in various distribution configurations has been simulated. The position and the power of each source have been optimized and the calculations have been validated by experimental measurements. High plasma densities > 10^11 cm^-3 over large areas > 400 mm in diameter with only 13 plasma sources have been achieved with all tested gases. An increase of compactness i.e., increasing the sources number over the same area, allows to have the same plasma surface while increasing the plasma density up to 5×10^11 cm^-3.