Abstract

Understanding the dynamics of the laser-induced chlorine etching of silicon requires clarification of the mechanisms by which the photons interact more or less concurrently with the reacting gas, the surface adsorbate and the silicon substrate. To clarify the etching mechanism it is generally recognized that it is desirable to separate the relative contributions from: excitation and dissociation of the reacting gas, Maxwell-Boltzmann heating of the substrate, formation of an altered surface, dissociation, formation and desorption of surface products, generation of electron-hole pairs id the subsurface and the stimulation of new quantum mechanical channels for reaction.¹ Although much work has been done on these effects, most of the studies with some exceptions, have not focused on surface characterization and have been carried out at relatively high laser fluences. Hence, the microstructure and composition of the target surfaces have not always been adequately defined. Interpretation of the reaction mechanisms tend to be obscured by thermal effects and the nature, time and energy features of the emitted products have not always been completely resolved. The objective of this work is to clarify some of these issues. The factors of laser fluence and sample doping are specifically addressed. With reference to our system we have chosen one in which there is no etching in the absence of the photon beam, and gas-photon interactions are minimized at the pressures used.

© 1991 Optical Society of America