Electron-beam assisted physical vapor deposition of polycrystalline silicon films

Polycrystalline silicon films have been deposited on different substrates using conventional e-beam evaporation in a vacuum environment of 2×10-6 Torr with controlled beam current and time of deposition at moderately low temperatures. Bare and thermally oxidized single crystalline polished silicon surfaces, micro-slides of glass and alumina were used as substrates. The deposited film of 2000 Å was analyzed using SEM, PL, EDS and GA-XRD for its polycrystalline nature and grain size. Grain size in the range of 40–60 nm was recorded on all the substrates. PL provided a band gap of 1.16 eV to resemble with polycrystalline silicon. The presence of atomic planes observed in XRD, confirms the polycrystalline nature of the deposited film. A monotonous decrease of sheet resistivity of the deposited film doped with boron with increasing doping temperature has been shown for polycrystalline nature of the film and its device applications. The results indicate the conventional e-beam evaporation method to be a cost effective substitute of CVD and MBD methods for depositing polycrystalline thin films with controlled grain size and density, in the fabrication of devices and sensors. The method has direct relevance for realizing piezoresistive thin films for MEMS devices.