ECR plasma has been used to deposit silicon, silicon germanium, silicon carbides, oxides and nitrides films. In this research, we study the correlation between amorphous silicon growth rate and plasma properties. Optical Emission Spectroscopy (OES), Mass Spectroscopy (MS) and Langmuir Probe are used to perform plasma analysis. We investigate the effect of microwave power, pressure, substrate bias and H2/He dilution on plasma composition. UV/VIS/NIR photospectroscopy is used to measure film thickness and to calculate film growth rate. We find a good correlation between amorphous silicon growth rate and SiH emission intensity.