Increased pattern transfer fidelity of ZEP 520A during reactive ion etching through chemical modifications by additional dosing of the electron beam resist

Abstract

This article describes a postdevelopment, additional electron exposure to enhance the etch selectivity and improve pattern transfer fidelity of an electron beam resist, ZEP 520A, through chemical changes of the resist. After the critical features were patterned and developed, the resist was exposed at 5 kV accelerating voltage to a second dose of electrons ranging from 300 to 300 000 μC/cm2. The etch rate of the resist decreased by approximately 25% in a CHF3 and O2 plasma. More critically, the fidelity of the pattern transfer was improved. Infrared and Raman spectroscopies were used to characterize the resist before and after electron beam exposure for doses up to 3000 μC/cm2. The carbonyl bonding in the polymer showed significant changes after electron beam exposure that can be associated with improvement in the etch performance of this resist.