Low Temperature Germanium Growth on Silicon Oxide Using Boron Seed Layer and In Situ Dopant Activation

Low temperature (<350°C) growth of germanium (Ge) on silicon dioxide (SiO 2 ) is demonstrated using a diborane pretreatment technique. Using SiH 4 and B 2 H 6 precursors, Si 1-x B x layers are deposited on Si0 2 to seed the chemical vapor deposition growth of Ge films. In the SiH 4 :B 2 H 6 system, the binary deposition mechanism of the Si 1-x B x film is explained by the "enhancement" model. In situ doping of Ge films is also investigated. In situ boron activation is achieved during the crystallization of the Ge films at 310°C. Device applicability of the doped Ge film growth on oxide is demonstrated in a low temperature (350°C) Si p-channel metal-oxide-semiconductor field-effect transistor, in which the Ge layer is used as a gate electrode. The low temperature Ge growth technique can be used for low thermal budget processes, e.g., monolithic three-dimensional integrated circuits.