Atomic-layer deposition of silicon nitride

Atomic-layer deposition (ALD) of silicon nitride has been investigated by m eans of (1) plasma ALD in which a NH3 plasma is used, (2) catalytic ALD in which NH3 is dissociated by thermal catalytic reaction on a W filament, and (3) temperature-controlled ALD in which only a thermal reaction on the sub strate is employed. The NH3 and the silicon source gases (SiH2 Cl-2 or SiCl 4) were alternately supplied. For all these methods, the film thickness per cycle was saturated at a certain value for a wide range of deposition cond itions. In the catalytic ALD, the selective deposition of silicon nitride o n hydrogen-terminated Si was achieved, but, it was limited to only a thin ( <4 nm) film. In the plasma ALD, selective deposition was hardly achieved du e to the hydrogen atoms generated in the NH3 plasma. The temperature-contro lled ALD succeeded in a selective deposition on Si and a little deposition on SiO2 at relatively large growth cycles due to the high-temperature react ion on the SiO2 surface, i.e., adsorbed Si+SiO2-->2SiO (evaporative).