Improved etch resistance of ZEP 520A in reactive ion etching through heat and ultraviolet light treatment

The authors have developed a treatment process to improve the etch resistance of an electron beam lithography resist (ZEP 520A) to allow direct pattern transfer from the resist into a hard mask using plasma etching without a metal lift-off process. When heated to 90 °C and exposed for 17 min to a dose of approximately 8 mW/cm2 at 248 nm, changes occur in the resist that are observable using infrared spectroscopy. These changes increase the etch resistance of ZEP 520A to a CF4/O2 plasma. This article will document the observed changes in the improved etch resistance of the ZEP 520A electron beam resist.