In-Situ Detection of Plasma Processing Equipment Using a V-Mask Control Chart.

To improve equipment throughput and device yield, plasma processing equipment should be tightly monitored. A cumulative-sum (CUSUM) control chart is used to monitor off-line process qualities. In this study, a V-mask control chart (VCC) is presented for detecting in-situ process variability. This consisted of a modified cumulative-sum and a V-mask-parameterized belief function. The presented control chart was applied to monitor a radio frequency matching of plasma impedance. Experimental data were measured by using a real-time impedance monitoring system. Detection performance was studied either for the fixed or time-varying VCC parameters. Analysis was more detailed by defining several diagnostic parameters. The detection performance of VCC monitor system was very sensitive to the variations in the design parameters. Optimizing the impact of design parameters considerably improved the detection performance of VCC system. In particular, VCC employing time-varying parameters demonstrated improved detection accuracy. The presented technique can be utilized to monitor other in-situ equipment data. [ABSTRACT FROM AUTHOR]