Douglas A. Sexton

Excimer Laser-Assisted Etching of Silicon Using Chloropentafluoroethane

Abstract : Laser-assisted photothermal chemical reactions have been observed with silicon in a chloropentafluoroethane ambient using a Krypton Fluoride laser at 248 nm. Etching occurs only if the incident fluence exceeds the melt threshold (approx. 0.75 J/sq. cm), and is monitored by the changes in silicon reflectance at 633 nm Aboce the abalation threshold (approx. 2.2J.sq. cm) increased surface roughness is observed. Etch rates approx. 7 A/pulse have been measured using both stylus profilometer and SEM cross-sectional techniques. The etch rate dependence on incident fluence, ambient pressure, doping concentration, crystal orientation and substrate temperature will be presented. This process allows single step patterning of silicon devices in a non-corrosive environment. Keywords: Charge coupled devices; Reprints.