Laser-Enhanced Chemical Etching of Solid Surfaces

The laser-enhanced chemical etching of Si, SiO
2
, Ta, and Te films with halogen-containing gases excited by a pulsed CO
2
laser and a continuous-wave (cw) Ar
⁺
laser has been studied. Detailed measurements of the etch rates as functions of the laser frequency, the laser intensity, and the gas pressure have been performed for some of the gas-solid systems. The enhanced surface reactions have been classified into three categories: those activated by the vibrational excitation of the etchant molecules, those with radicals generated by photodissociation, and those induced by laser excitation of solid substrates. Examples which illustrate the effects of laser radiation on these surface photochemical processes are given. Achievable etch rates and spatial resolutions for the various reaction mechanisms are also examined.