Evaluation of Phosphine-Oxygen Diffusion System as a Process for Silicon Integrated Circuit Fabrication

摘要

Experimental conditions for the attainment of sheet resistance with high reproducibility at emitter doping levels have been obtained using the gaseous PH3-O2 process. Under these conditions, the deposition sheet resistance follows an activation energy relationship with temperature (with E = 2.9 eV between 1000 and 1100C), and is independent of background doping and oxygen concentration within pluse or minus 2.3% control limits. At temperatures below 1000C, there is an apparent dependence on both background doping and O2 concentration, and the process appears less saturated than that above 1000C. The two-step process shows that the final diffused sheet resistance and junction depth can be predicted from the deposition sheet resistance. The process has been successfully applied in the fabrication of emitters for integrated NPN transistors with no visible surface damage, and it is fully compatible and simple in operation. (Author)