Selective epitaxial growth by ultrahigh-vacuum chemical vapor deposition with alternating gas supply of Si2H6 and Cl-2

Selective epitaxial growth of Si using a Si3N4 mask has been carried out by ultrahigh-vacuum chemical vapor deposition with an alternating supply of d isilane (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 depos ited on Si3N4 with Cl-2, while grown film structures depend on the substrat e 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 temp erature (600 degreesC). On the other hand, the passivation effect weakens w ith increasing temperature and thus the epitaxial him thickness is determin ed by both the growth rate with Si2H6 and the etching rate with Cl-2 on Si.