PULSE-LENGTH STUDIES OF POLYMER ETCHING WITH EXCIMER LASERS: IN SEARCH OF TWO-PHOTON AND SATURATED ABSORPTIONS.

Abstract

Summary form only given. In an effort to better understand the mechanism by which organic polymers are ablatively etched when exposed to high-energy pulses of ultraviolet laser radiation, the etch rate dependence of AZ photoresist, poly(methylmethacrylate), and polyimide on laser fluence and laser pulse length was examined. The temporal length of an excimer laser pulse at 308 nm has been doubled by combining 40-ns pulses. Pulses shorter than 40 ns have been generated within a Xe spark cell, wherein the high fields of the focused laser light result in gas breakdown and subsequent absorption of the trailing edge of the pulse. Measurements with 10-, 40-, and 80-ns pulse lengths are included.