Reactive-ion etching of Ge 2Sb 2Te 5 in CF 4/Ar plasma for non-volatile phase-change memories

Abstract

Etching of Ge 2Sb 2Te 5 (GST) is a critical step in the fabrication of chalcogenide random access memories. In this paper, the etch characteristics of GST films were studied with a CF 4/Ar gas mixture using a reactive-ion etching system. We observed a monotonic decrease in etch rate with decreasing CF 4 concentration indicating its importance in defining the material removal rate. Argon, on the other hand, plays an important role in defining the smoothness of the etched surface and sidewall edge acuity. We have studied the importance of gas mixture and RF power on the quality of the etched film. The smoothest surfaces and most vertical sidewalls were achieved using a CF 4/Ar gas mixture ratio of 10/40, a background pressure of 80 mTorr, and power of 200 W.