GAS/SURFACE INTERACTIONS RELEVANT TO CHEMICAL VAPOR DEPOSITION TECHNIQUES.

Abstract

Low Pressure Chemical Vapor Deposition (LPCVD) is widely used to prepare high quality silicon thin films for use in a variety of device applications. The authors have demonstrated that phosphine adsorbs with unity probability on available Si surface sites, and this layer passivates the surface with respect to the subsequent adsorption of silane. These results confirm the suspected mechanism whereby phosphine addition suppresses silicon deposition in the LPCVD process. It was found that diborane is very weakly adsorbed on the Si surface, which is also consistent with its interactions with silane during LPCVD in that it is not observed to disrupt film growth. The known behavior of other dopant species such as arsine agrees with this model, as it's valence structure matches that of phosphine and it produces like effects.