Selective epitaxial growth by ultrahigh-vacuum chemical vapor deposition with alternating gas supply of Si2H6 and Cl2

Selective epitaxial growth of Si using a Si3N4 mask has been carried out by ultrahigh-vacuum chemical vapor deposition with an alternating supply of disilane (Si2H6) and chlorine (Cl-2) gases. In the present gas supply method, selectivity of Si to Si3N4 is attained mainly by etching of poly-Si deposited on Si3N4 with Cl-2, while grown film structures depend on the substrate temperature and the total supply of Si2H6 and Cl-2 gases. The passivation effect of chlorine on growing film surfaces dominates at a low growth temperature (600 degreesC). On the other hand, the passivation effect weakens with increasing temperature and thus the epitaxial him thickness is determined by both the growth rate with Si2H6 and the etching rate with Cl-2 on Si.