Power dissipation mechanisms in radio-frequency driven silane discharges: The influence of discharge geometry

Abstract

The influence of chamber geometry on the electron impact dissociation and dissociative excitation processes, in a capacitively coupled radio-frequency (rf) silane discharge, is presented. This is achieved by examining the influence of geometry, in conjunction with other macroscopic parameters, on the concentrations of ground state SiH and electronically excited SiH* radicals, recorded simultaneously by spatially resolved laser induced fluorescence and optical emission spectroscopy. The geometry of the discharge is modified, by changing either the interelectrode distance or the electrode diameters, whereas the electric symmetry of the discharge is monitored by the change of the self-bias direct-current potential of the rf electrode. Our observations indicate that the specific path and power consumption of the generation processes of the two radicals are spatially differentiated and sensitive to geometry variations. Thus, emission and fluorescence spatial intensity profiles are differently influenced. In the case of the modification of interelectrode distance, a redistribution of the energy consumed by each of the radical generating processes has been observed.