Paper PS2-ThM7
On-wafer Real Time Monitoring of Charge-Build-up Voltages during Plasma Etching in Production Equipment

Thursday, October 18, 2007, 10:00 am, Room 607

For requirements of high performance and large scale integration to semiconductor devices, transistor size has been shrunk down to nano-scale regime. Recently, 32nm gate length has been already developed and even 22nm gate length is under studying. As a result, gate insulator thickness of MOSFETs must be thin as less than 1nm in 22nm technology. Consequently, gate oxide breakdown caused by the plasma damage is a significant concern. In addition, extraordinary shape of via hole and etching stop caused by the electron shading effect must be solved to realize high aspect ratio via holes.These issues are attributed to charge-up during plasma etching processes. It is absolutely necessary for solution of them to monitor charge-up phenomena precisely. There are two typical methods to monitor them so far. One is measurement of electrical charge on the blank wafer after processing. The other is charge monitoring by using NVM(Nonvolatile memory). However, both methods dose not function for monitoring them in real time or on the actual patterned wafer. Consequently, the charge-up phenomena during device fabrication plasma etching can not be understood in detail.We succeed to monitor real time charge-up phenomena on the actual patterned wafer by using On-Wafer Monitoring Sensor newly proposed by Dr. Samukawa. In this study, an etcher for production was employed. From data of charge-up quantity under various etching conditions such as gas chemistry, RF power and pressure with various types of On-Wafer Monitoring Sensors, the charge-up phenomena can be revealed and will be reported in the presentation.