Causes of small particle growth in silane discharges

Silicon-based particles that grow in a silane radio frequency (RF) discharge are studied by light scattering. Average particle size and the corresponding particle density are measured as functions of silane density, RF voltage, and chamber temperature (T). The particle density is almost independent of T, as is the film growth rate. In contrast, the particle-size growth rate (G) decreases by a large factor as T increases from 300-500degreesK. It is also observed that the few percent of higher silanes that are produced by the discharge cause a major increase in G.