Kinetics of the many‐stage process of particle nucleation and growth in low‐pressure rf discharge in silane SiH4–Ar is considered. The particle growth is considered in an analytical model as a chain of negative‐ion molecular reactions, stimulated by vibrational excitation. In the framework of this model, a limitation of first generation particle size is explained as well as the strong temperature effect on cluster growth. A theory of critical phenomena of cluster trapping in discharge area has been elaborated to describe the neutral particle selection by size, and the particle concentration increases during a period exceeding the residence time in plasma. Finally, an analytical model of critical phenomena of particle coagulation and its influence on plasma parameters is developed to explain the latest experimental results on supersmall 2–10 nm cluster kinetics. All theoretical results are presented in comparison with corresponding new experimental data and with results of an especially made computer simulation. ©1996 American Institute of Physics.