Removal of Diazonaphthoquinone/Novolak Resist Using UV Laser (266 nm)

This study revealed a promising method for removing positive-tone diazonaphthoquinone/novolak resist. The fourth harmonic of an Nd3+:YAG (Y3Al5O12) pulsed laser (266 nm) was irradiated onto the resist. Resist was removed when laser power exceeded 35 mJ/cm2, and a 250 nm-thick resist was removed with a laser power of 94 mJ/cm2. X-ray Photoelectron Spectroscopy (XPS) proved that 1100 nm-thick resist could be completely removed from a Si surface when it was irradiated almost 700 mJ/cm2. The resist onto three inch Si wafer (45.58 mm2) was removed in two minutes by laser. No damage to the processed Si wafer could be detected by optical microscopic observation. This method is good for environment.