STUDY ON GROWTH-PROCESSES OF SUBNANOMETER PARTICLES IN EARLY PHASE OFSILANE RF DISCHARGE

Growth processes of particles formed in an early phase of silane RF pl asmas are investigated using the modified Langmuir probe, spectroscopi c and photodetachment methods. From the probe measurements, the partic les are estimated to be on the order of subnanometer size, and they ar e found to nucleate and grow principally around the plasma/sheath boun dary near the RF electrode, where optical emission intensity of SiH ra dicals is high. These spatial profiles are different from those of pos itive and negative ion densities during discharging periods. These res ults suggest that many short-lifetime neutral radicals are necessary f or the nucleation and subsequent growth of a particle. The photodetach ment experiments and scanning electron microscope (SEM) observation al so show that the particles are in the size ranges below about 200 atom s and about 1 nm. Spatial profile measurements of probe currents and n egatively charged particle density obtained by the photodetachment met hod confirm that the mass of the particles around the plasma/sheath bo undary near the RF electrode is large.