THE MECHANISM OF PLASMA-INDUCED DEPOSITION OF AMORPHOUS-SILICON FROM SILANE

Time-resolved mass spectrometric data show that the concentration of di- and trisilane, which are formed from monosilane under discharge conditions typical for the deposition of high electronic quality amorphous silicon, correlate with the measured deposition rate of a-Si. The data can be quantitatively and self-consistently described by a simple set of consecutive reactions: 1. SiH4 →-SiH2 + H2 2a. SiH2 + SiH4 → Si2H6 2b. SiH2 + Si2H6 → Si3H8 3. Sin H2(n + 1) →n ·a-Si:H+(n+1)H2, n=2,3 The only fitting parameter necessary for an excellent fit of the measured data over a wide range of experimental parameters is the value of the reactive sticking coefficient .for the decomposition of di- and trisilane (reaction 3). The resultant value agrees well with the published data of other authors and with those calculated from the measured deposition rate and Si2H6, concentration. We did not find and physically meaningful way to lit the measured data with the various "SiH3 models" proposed by other authors who assumed that the dominant species responsiblefor the deposition of a-Si: H is the SiH3, radical. For this and some additional reasons mentioned in the present paper. the SiH3 model is in disagreement with available experimental data. © 1990 Plenum Publishing Corporation.