Effect on Etch Rate and Surface Roughness of Crystal Orientation of Polycrystalline Silicon Used for Consumable Parts of Reactive Ion Etching Equipment

Abstract

Silicon is used for consumable parts in reactive ion etching (RIE) equipment because it generates fewer particles, which decrease the yield, than other materials. Polycrystalline silicon is usually used for top electrodes, especially in high-aspect-ratio RIE, to increase the wafer’s self-bias. In this study, the relationships among the crystal orientation of the polycrystalline silicon used in RIE equipment, grain size, grain boundary length, etch rate, and surface roughness were investigated. The grain size and the etch rate decreased as the percentage of Si(111) in the polycrystalline silicon increased. The grain size and etch rate for 47% Si(111) decreased to 66.4% and 84.7%, respectively, compared with 8% Si(111). Moreover, the grain boundary length and surface roughness increased as the percentage of Si(111) increased. The grain boundary length and surface roughness for 47% Si(111) increased by 1.8 and 19.6 times, respectively, compared with 8% Si(111). Therefore, as the percentage of Si(111) increased, the grain size and etch rate decreased, whereas the grain boundary length and surface roughness increased.