Phosphorus atomic layer doping in Si using PH₃

Atomic layer doping of P (P-ALD) in Si is investigated using reduced pressure chemical vapor deposition (RPCVD). For P-ALD, PH₃ exposure on Si (100) surface followed by Si cap layer deposition using SiH₄ or Si₂H₆ is performed. P adsorption is suppressed by hydrogen-termination of the Si surface. On the hydrogen-free Si surface, the P adsorption is increasing with increasing PH₃ exposure temperature saturating at temperatures above 600°C. P adsorption is also increasing with increasing PH₃ exposure time. It tends to saturate at long exposure time indicating a self-limitation of the process. By Si deposition using Si ₂H₆, higher P peak concentration and higher P doping level in the Si cap layer is observed compared to those with SiH₄ based Si deposition. For both SiH₄ and Si₂H₆ based capping process lower P segregation is observed by lowering the growth temperature.