Paper PS2-WeA3
Time Dependence of Charge-Build-up Voltages in Production Etcher by On-Wafer Real Time Monitoring System

Wednesday, October 22, 2008, 2:20 pm, Room 306

Charge-build-up during plasma etching process is one of crucial issues to realize nano-scale devices. Because gate insulator thickness of such devices is shrunk down to 1nm range, the gate insulator breakdown caused by the charge-build-up is a key issue and has to be solved. To understand the phenomenon of the charge-build-up, it is absolutely necessary to monitor the time dependence of charge-build-up precisely. We have advanced charge-build-up monitoring sensors proposed by Dr.Samukawa. We have monitored etching parameters dependency and aspect ratio dependency in steady status in production etcher and have demonstrated effectiveness of the sensors. However, it was difficult to monitor charge-build-up phenomenon in unsteady status in detail. Therefore, we developed On-Wafer Real Time Monitoring System which can measure the data of charge-build-up voltages at the timing of several micron seconds and can record charge-build-up voltages in processing in production etcher. In general, the recipes in production etchers have several sequential etching steps. Unstable plasma tends to occur especially at the time of chucking wafer electro-statically, turning on-off plasma discharge and switching the etching step. As a result, they induce plasma damages. Therefore, it is important to monitor charge-build-up voltages not only in steady status, but also in unsteady status. In this study, we monitor the time dependence of charge-build-up voltages in processing in production etcher by On-Wafer Real Time Monitoring System and the charge-build-up phenomena in unsteady status will be discussed in detail in the presentation.