# Real-Time Small Exposed Area $SiO_2$ Films Thickness Monitoring in Plasma Etching Using Plasma Impedance Monitoring with Modified Principal Component Analysis

• 장해규 (성균관대학교 나노과학기술학과) ;
• 남재욱 (성균관대학교 화학공학부) ;
• 채희엽 (성균관대학교 나노과학기술학과)
• 발행 : 2013.02.18

#### 초록

Film thickness monitoring with plasma impedance monitoring (PIM) is demonstrated for small area $SiO_2$ RF plasma etching processes in this work. The chamber conditions were monitored by the impedance signal variation from the I-V monitoring system. Moreover, modified principal component analysis (mPCA) was applied to estimate the $SiO_2$ film thickness. For verification, the PIM was compared with optical emission spectroscopy (OES) signals which are widely used in the semiconductor industry. The results indicated that film thickness can be estimated by 1st principal component (PC) and 2nd PC. Film thickness monitoring of small area $SiO_2$ etching was successfully demonstrated with RF plasma harmonic impedance monitoring and mPCA. We believe that this technique can be potentially applied to plasma etching processes as a sensitive process monitoring tool.