Epitaxial Si1−x Gex grown into fine contact hole by ultrahigh-vacuum chemical vapor deposition

An ultrahigh-vacuum chemical vapor deposition technique with disilane (Si2H6) and germane (GeH4) molecular flux is applied to Si1−xGex (x=0–0.15) selective growth into fine contact holes. The growth behavior of epitaxial Si1−xGex layer is influenced by addition of GeH4 with Si2H6 flow rate kept at constant, which is interpreted by estimation of facet growth rates. The growth rates of (311) and (111) facets are drastically decreased by addition of a small amount of GeH4. As a result, in the fine holes, the epitaxial layer height of Si1−xGex is limited by the (311) growth rate and decreased compared with pure Si.