Microstructure and Pore Characteristics of a Double-Layered Pore Structure Powder Filter Fabricated by the WPS Process

Abstract

In order to supply high-purity process gas in the semiconductor manufacturing process, a gas filter is used to remove particles that may be contained in the gas. However, because the gas filters currently in use have simple pore structures, there is a need to increase filtration efficiency through the development of filters with complex pore structures. In this study, a metal powder filter with double-layered pores was manufactured using a Wet Powder Spraying process (WPS) to increase the filtering efficiency of gas filters used in semiconductor manufacturing. The effects of the mixing ratio of spherical-shape and flake-shape powders and the rolling process on the filter’s characteristics were investigated. The filter’s performance, microstructure, and surface roughness were evaluated by measuring porosity and gas permeability. The results showed that as the ratio of flake-shaped powder decreased, the thickness of the coating layer and the porosity of the filter decreased. Additionally, it was observed that as the rolling process progressed, the non-uniform pore structure was oriented parallel to the cross-section of the filter regardless of the mixing ratio. Measurements found that the gas permeability of the uncoated filter support was the highest, and that gas permeability decreased as the proportion of spherical powder increased regardless of the average particle size of the mixed powder. Lower gas permeability was observed in rolled samples. A filtration efficiency of LRV 3 or higher was confirmed.