A supersonic molecular beam study of the chemisorption of PH3 on the Si(100) surface

[摘要] The dissociative chemisorption of phosphine, PH3, on the Si(100) surface has been examined with supersonic molecular beam scattering techniques. The effect of phosphorus adatoms, P(a), formed by the dissociative chemisorption of PH3, on the reaction of SiH4 and Si2H6 with Si(100) has also been characterized. All reactions have been examined at substrate temperatures characteristic of steady-state Si thin film growth, i.e. T-s greater than or equal to 450 degrees C. The reaction probability, S-R, for PH3 on Si(100) decreases with increasing substrate temperature and the kinetic energy of the incident molecule, suggesting that chemisorption proceeds via a trapping precursor-mediated dissociation channel. The dependence of PH3 dissociative chemisorption on the fractional coverage of P(a) and H(a) has been deduced under conditions where the desorption of H-2 and P-2 are finite. The dependence of the dissociative chemisorption of both SiH4 and Si2H6 on the coverage of P(a) has also been determined. For reaction conditions under which P(a) is the dominant surface species, the reaction probabilities of PH3, SiH4 and Si2H6 are proportional to the quantity 1 - theta(P)(2), where theta(P) is the fractional coverage of the adsorbed phosphorus atoms. In addition, the presence of phosphorus adatoms has also been found to have a significant influence on the reaction pathway of Si2H6 on Si(100). Our results have been employed to formulate a predictive model for the kinetics of Si thin film growth in presence of PH3(g).

[发布日期] 1995-12-30

[关键词] adatoms;disilane;low index single crystal surfaces;models of surface chemical reactions;molecule solid reactions;phosphine;phosphorus;semiconducting films;semiconducting surfaces;silane;silicon;solid-gas interfaces;surface chemical reaction