Improvement of High Aspect Ratio Contact Etching Performance by using Real-Time Wafer Temperature Control (1st Report)

—Prototyping of a Basic Equipment and Evaluation of the Temperature Control Effect on Etching Process—

Abstract

Novel wafer-cooling system based on direct expansion phenomenon of coolant has been developed in order to improve etching performance for high-aspect-ratio contact (HARC) process. This system provides effective cooling capability and rapid wafer temperature control. In this study, prototyping of basic equipment was performed and etching performance in HARC process was evaluated. As a result, temperature control speed of 0.6 °C/s was achieved over a 300mm-φ wafer. Furthermore, etching rate and mask selectivity at 100nm-φ, aspect-ratio of 20 HARC sample could be increased by around 6% and 14% respectively without any etching profile deformation by 2-step wafer temperature control from 61°C to 50°C during etching in C₄F₆/Ar/O₂ plasma. It is concluded from the results that this system can improve etching performance for HARC.