CD uniformity improvement and IC process monitoring by wireless sensor technology

Abstract

A new wafer-level wireless temperature sensor technology was developed for in-situ etch process performance monitoring and improvement of critical dimension control in litho process. For plasma etch application, the system is shown to be cost-effective, reliable, and easy to implement within any commercially available plasma chambers. In addition, a new level of process insight along with optimization opportunities can be realized from the system's implementation. For litho application, critical dimension (CD) uniformity control is one of the major challenges for DUV process due to high-temperature sensitivity of 193nm chemically amplified resist in the post-exposure bake (PEB). The PEB step has been traditionally calibrated for optimum across hot plate temperature uniformity at static, steady state by utilizing wired temperature sensor technology. For sub-100nm technology nodes, however, current method is insufficient for tightening CD control. A real time monitor and full thermo-profile study is needed instead. In this paper the new wireless temperature sensor metrology is demonstrated to achieve both temperature uniformity and CD uniformity improvement.