A Method of Controlling Wafer Surface Polarity to Reduce Spacer Particle Contamination

摘要

In general process, there is a polymer removal step by CR-SPM (Caros' acid clean) or STD clean (Standard Clean) after spacer etching. Sometimes the particles are found by KLA scan right after CR/STD clean, but not found after spacer etching. After studying the characteristics of particles, the formation of particles that contained in CR/STD tank are attached on OD area surface. In this report, a whole new in-situ polarity modification concept that changing hydrophobic Si surface to hydrophilic SiO surface by adding a very short O_2 plasma treatment right after spacer etch is presented. The concept is evaluated in bare silicon and TEOS control wafers, and the results reveal that O_2 plasma treatment can avoid particle attachment not only effectively but also efficiently. By the experiment, in-situ five seconds' O_2 plasma is implanted in spacer etching recipe and two products are spilt to test. The WAT (Wafer Acceptance Test) and yield of split are comparable with standard condition.