Establishment of process monitoring for production availability improvement

Stable operation of production facilities and equipment is essential for efficient production. Currently, however changes in equipment operation often cause problems in production processes. To prevent these problems, we studied and developed a system that continuously monitors process states. We first selected equipment parameters that are most likely to affect process characteristics and monitored these parameters. A comparison between the monitored data and the standard process characteristics revealed that the voltage for opening the wafer-cooling gas pressure control valve ("valve opening voltage") was positively correlated with the intra-wafer uniformity of the etching rate. We have developed a system that can indirectly detect changes of the uniformity of the etching rate by continuously monitoring the valve opening voltages.