Ultrashort-pulse laser heating of silicon to reduce microstructure adhesion

A technique to remove moisture from microelectronic devices and improve device yield in microelectromechanical systems by reducing microstructure surface adhesion is proposed. Ultrashort-pulse laser radiation is used to create excited carriers in, and consequently desorb water from, silicon microstructures. A theoretical model for ultrashort-pulse laser heating of silicon is presented. Calculated carrier temperatures show significant increases at short time scales, while the lattice temperatures remain almost constant, indicating the possibility for water desorption without significant device healing. A preliminary experiment confirming the feasibility of using the technique to decrease microstructure adhesion is discussed. Copyright (C) 1996 Elsevier Science Ltd.