AVS 45th International Symposium
    Thin Films Division Friday Sessions
       Session TF-FrM

Paper TF-FrM8
Assessment of As-deposited Polycrystalline Silicon Films on Polymer Substrates using ECR-PECVD

Friday, November 6, 1998, 10:40 am, Room 310

Session: Thin Film Deposition from Chemical Precursors
Presenter: S.H. Bae, The Pennsylvania State University
Authors: S.H. Bae, The Pennsylvania State University
S.J. Fonash, The Pennsylvania State University
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As-deposited polycrystalline silicon (poly-Si) films have been successfully grown on polymer substrates at 120 and 200 °C using ECR (Electron Cyclotron Resonance) PECVD. PES (polyethersulfone) and PET (polyethylene terephthalate) substrates have been used in this work. To block diffusion and degassing from the polymer substrates, 1000 Å ECR-PECVD silicon nitrides (refractive index = 1.9) have been coated on the substrates prior to Si film depositions. Then, Si films have been deposited with SiH@sub 4@/H@sub 2@ ECR plasmas. The structural, opto-electric and electrical characteristics of Si films have been assessed by X-ray diffraction, photoluminescence, and electrical conductivity measurements, respectively. X-ray diffractions for 3500 Å Si films grown at 120 and 200 °C have shown (111), (220), (311) and (331) peaks which are the primary diffraction peaks of crystalline Si materials. We have explored the effect of the 13.56 MHz RF substrate bias during growth of Si films. According to X-ray diffraction patterns, low RF substrate bias and high substrate temperature are favorable for high degree of crystallinity of Si films. It is noted that RF substrate bias during ECR plasmas may tailor electrical properties of as-deposited poly-Si films; as the RF substrate bias is applied and increased, conductivities are improved and activation energies are decreased. In photoluminescence spectra of Si films, the intensity of luminescence is enhanced as RF bias is increased. Since intensity of photoluminescence is related to defect density of Si films; the more defects offer the more alternative paths for non-radiative recombination which compete with radiative recombination paths, enhancement of photoluminescence intensity with applying RF bias may mean that degree of defect passivation during Si film growth is controlled by RF substrate bias.