Identification of process parameters for microfabrication with excimer laser

Abstract

The ablation of a polymethyl methacrylate (PMMA) substrate with a 248-nm long-pulsed KrF excimer laser is studied. PMMA is ablated at a laser pulse repetition rate (PRR) of 2, 5, and 10 Hz, and fluence varying from 0.2 to 1 J/cm(2). The coupling effects of multiple shots, PRR, and fluence on the etching depth and topography of PMMA are discussed. It is observed that the etching rate and the ablation depth increase with the increase in fluence. The increase in the ablation depth with fluence is more significant at a higher number of shots. It is also observed that the etching rate decreases with the number of shots for a given fluence. An optimal combination is selected for the fabrication of a 100-mu m-depth microchannel using styrene mask. The current microfabrication technique also demonstrates the use of low-cost masks. (C) 2007 Society of Photo-Optical Instrumentation Engineers.