Study on Uniform Plasma Generation Mechanism of Electron Cyclotron Resonance Etching Reactor

Abstract

Electron cyclotron resonance (ECR) plasma sources have been used widely in ultra large-scale integration (ULSI) manufacturing processes for many years. ECR plasma sources can generate plasma stably, even at very low pressures below 0.1 Pa, and the plasma’s spatial distribution can be controlled easily using the static magnetic field distribution. Furthermore, the plasma generation region can be located away from the chamber walls, which leads to reduced plasma contamination from the walls. In addition, uniform plasmas can be generated using these sources to achieve uniform plasma processing, which is crucial for large-diameter wafers such as 300 or 450 mm wafers. However, the mechanism for generation of uniform plasma using an ECR plasma source for semiconductor manufacturing is not well understood because of the complexity of the microwave propagation in the plasma. We use a plasma simulation technique to understand the uniform plasma generation mechanism in this work. We have conducted an integrated ECR plasma simulation of an etcher used for semiconductor manufacturing that combines 1) a microwave analysis in magnetized plasma, 2) a plasma generation analysis, and 3) a plasma diffusion analysis. We obtained consistent solutions for each analysis in practical calculation times of a few minutes. Additionally, we verified the simulation results by comparison with experimental plasma density measurements. We then discussed the uniform plasma generation mechanism in the ECR plasma source using simulated results for the microwave distribution in the etching reactor.