Polycrystalline silicon thin films for MEMS applications

摘要: Abstract Thanks to its interesting mechanical and electrical properties, silicon represents the first candidate as a structural material in Micro Electro Mechanical Systems field. Doped polycrystalline films are generally used, particularly when electrostatically movable structures needed. Here, we investigate effects of doping type well post-deposition thermal treatments on behaviour situ doped deposited by low pressure chemical vapour deposition from mixture silane SiH4 phosphine or diborane. Stress measurements, performed using micro-Raman spectroscopy, related micro fixed–fixed beams determined optical scanning electron microscopy observations. The films, regardless their type, found tensely stressed amorphous solid phase crystallised at 600 °C. tensile stress is reduced becoming compressive crystallization temperature increased. An optimum value, corresponding maximum beam free length, determined. Finally, air-gap thin film transistors (TFTs) these realised. Electrical parameters TFTs (field effect mobility, threshold voltage, subthreshold slope) may be considered good. Particularly value 2.5 V, very for handling devices where power consumption saving crucial.