CONTRIBUTION OF INDIVIDUAL PROCESS STEPS ON PARTICLE CONTAMINATION DURING PLASMA CVD OPERATION

摘要

A method was proposed to determine the occurrence time and the contribution level of particle contamination from individual process steps during plasma-enhanced chemical vapor deposition (PECVD) operation. The proposed method is based on the capability of thermophoresis to shield the wafer from particle deposition. The occurrence time and the contamination level were determined by comparing the number of particles deposited on the wafer at the conditions of with and without applying thermophoresis in the postplasma period. We found that the occurrence time and the contamination level are dependent on the plasma operating condition, i.e. the particle trap behavior. Particle contamination occurs during postplasma at low to intermediate gas flow rate whereas it occurs during plasma operation at high gas flow rate. The level of contamination decreases by increasing gas flow rate then reaches a minimum value and eventually increases again.