Temperature effect and stress on microcrystalline silicon thin films deposited under high pressure plasma conditions

An investigation of the effect of the deposition pressure (133.3-1333 Pa) on the mu c-Si:H crystallinity, stress and thermal stability was performed. The films were deposited from SiH4/H-2 discharges under constant power conditions and with constant silane partial pressure. The increase of pressure resulted in an optimum of the deposition rate at 333.3 Pa and an increase of the crystallinity as the pressure is raised from 133.3 to 333.3 Pa. The Raman spectra revealed a shift of the c-Si peak for all films towards lower wave numbers and this shift was much larger for the film deposited at 133.3 Pa. The effect of film stress and local heating in this shift was distinguished by investigating the effect of temperature on the position of the c-Si peak. The stress of the deposited films was found to be tensile for all pressures and much higher for the film deposited at 133.3 Pa. This result is discussed in terms of the deposition conditions pointing out the advantages of working at higher pressures. (c) 2005 Elsevier B.V. All rights reserved.