AbstractChemical vapour deposition (CVD) of silicon on various substrates is a well‐known technique in semiconductor technology.An experimental study has been made of the nucleation of silicon on SiO2, and Si3N4, substrates together with a search for rate‐limiting steps in the growth of silicon from silane (SiH4) and chlorosilanes.Analysis of the experimental data shows that the nucleation depends on the concentration of silicon adatoms on the surface, (Si*). After formation of stable nuclei and coalescence of the growing domains, further growth of silicon on silicon proceeds.For the growth of silicon via silane the rate‐limiting reaction could not be indicated exactly; addition of some HCl results in a rapid change of the surface species into SiCl2*, indicating that the rate‐limiting step has to be found at the end of the chain of surface reactions. This conclusion is confirmed by experiments with an input of SiH2Cl2, in which case the SiCl2* surface species predominates. Reduction to silicon is then found to be the rate‐limiting reaction. The reduction or desorption of chlorine probably takes place at specific sites on the surface, such as atomic surface steps where an adsorbed SiCl2, molecule can form a second silicon‐silicon bond.The adsorption of monoatomic hydrogen and chlorine on the silicon surface has been analysed and the conclusion is drawn that these surface species are not present in a sufficient concentration to turn the initial adsorption or the surface diffusion of silicon‐containing compounds into rate‐lim