Etching performance improvement on semiconductor silicon wafers with redesigned etching drum

Abstract

Etching process involves various chemical reactions and reflects significantly on the silicon wafer quality. The paper addresses the major problem on wafers during etching that is wafer removal distribution throughout etching drum compartment. The etchant used in this study were the composition of HNO3, HF, and CH3COOH. The etching drum has been redesigned to overcome the lower removal problem at the end of each compartment and to reduce the big disparity in wafer removal distribution. The proposed idea is to install a piece of "circumferential acid resistant PVC wafer" for the remaining empty slot (empty area without wafers) at each end of a compartment. The permanent PVC piece with certain gap at each end is then fabricated for the new drum design. The characteristics of the end wafers are compared with other wafers in the compartment to study the etching difference that leads to this problem. Surface morphology and surface roughness parameters (arithmetic roughness mean; Ra and surface skewness [roughness root mean square]; Rms) using atomic force microscopy (AFM) comparison between old drum design (big wafer gap) and new drum design (smaller gap with additional PVC chip) had been analyzed. The uniformity without lower removal problem at the end compartment is observed in removal distribution graph.