Effects of Process on the Coatings for Semiconductor Chamber Components

Plasma sprayed coating has been widely used over decades in semiconductor chamber components. However, due to current plasma spray coatings have high porosity & surface cracks, it caused high on-wafer particles. The cracks and inherent porosity can cause coating damage and peeling during wet cleaning because of chemical attaching the substrate. Because the repeatability of the coating was not good enough, it caused the chamber to chamber matching problem. In this paper, advanced in situ diagnostic tools were used to monitor and measure the process to understand the processing-microstructure-property relationships of coatings and the process fundamental. In-situ coating property sensor (ICP) was applied to monitor the layer by layer stress of the coating

Plasma spraying is a highly complex deposition process with a large number of interrelated variables. Powered materials are injected within the flame where particles are accelerated and melted, or partially melted, before they flatten and solidify onto the substrate (forming lamellae or splats), the coating being built by the layering of splats. Numerous engineering parameters, such as power level, primary plasma gas type and flow rate, auxiliary plasma gas type and flow rate, carrier gas flow rate, spray distance, spray angle, etc. have to be tried empirically and systematically through parameter matrix to determine the optimal parameters. The insight of the intermediate sub-processes and the corresponding mechanisms are largely unknown. In recent years, the development of in situ diagnostic tools has enhanced our ability to understand the processing-microstructure-property relationships of thermal spray coatings. Because the coating develops by successive impingement and inter-bonding among the splats, the particles temperature and velocity in the plasma flame play an important role in the coating properties. DPV 2000 was used to measure the particles state during spraying. The DPV 2000 provides on-line monitoring of individual particle characteristics in plasma spray plumes.