Poly-SixGei..x films were fabricated on 500 A of oxide by a novel process. Values for X range from 0.86 to 0.45. This novel process consists of two steps as opposed to the single step polysilicon germanium deposition methods currently used in industry. Ge was deposited by PVD and polysilicon was deposited on top of the germanium by LPCVD in a silane ambient. The films were doped P~ with boron dopant and annealed at 1,000°C for 50 minutes in a nitrogen ambient. Films with 65 and 55% Ge suffered from voids and hillocks and film discontinuity. Films with 20 and 14% Ge were relative smooth compared to the films with a high percentage of Ge. Standard polysilicon films yield a sheet resistance of 59.01 ohm/square while films with 20 and 14% Ge yield values of 44.71 and 41.41 ohm/square respectively
Medina, Jose L.
"Polysilicon-Germanium Films Fabricated by Ge Sputtering,"
Journal of the Microelectronic Engineering Conference: Vol. 11
, Article 10.
Available at: http://scholarworks.rit.edu/ritamec/vol11/iss1/10