Development and evaluation of die materials for use in the growth of silicon ribbons by the inverted ribbon growth process, task 2, LSSA project

Abstract

Silicon sessile drop experiments were performed on a variety of commercially available refractory carbides, nitrides, oxides, and borides to examine the potential of these materials for applications involving either direct contact with molten silicon or as substrates for CVD coatings in the fabrication of dies and crucibles for containing molten silicon. Simultaneous experiments were also conducted with CVD layers of SiC, Si3N4, and SiOxNy. Silicon nitride layers, deposited with NH3:SiH4 ratios ranging from 100:1 down to 5:1, were examined in sessile drop experiments to determine if the layers are degraded as a result of using lower reagent ratios. Preliminary experiments were undertaken on the stability of CVD Si3N4 near the melting point of silicon. Silicon ribbon segments were grown from vitreous carbon dies which had been coated with CVD Si3N4. Depending upon the purity of the die materials, ribbon resistivity values up to 40 Omega cm were obtained