AVS 45th International Symposium
    Thin Films Division Thursday Sessions
       Session TF-ThM

Paper TF-ThM9
Polycrystalline Silicon Films Deposited Directly on Glass by Reactive Magnetron Sputtering Using a Microcrystalline Silicon Nucleation Layer

Thursday, November 5, 1998, 11:00 am, Room 310

Session: Thin Films for Flat Panel Applications
Presenter: D.S. Kim, Samsung Advanced Institute of Technology, Korea
Authors: D.S. Kim, Samsung Advanced Institute of Technology, Korea
J.E. Gerbi, University of Illinois, Urbana-Champaign
J.R. Abelson, University of Illinois, Urbana-Champaign
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We investigate the microstructure of polycrystalline silicon (px-Si) thin films which are deposited directly onto glass substrates using reactive magnetron sputtering in a single-pumpdown, two step growth process. px-Si films are of technological interest as thin film transistors in flat panel displays and as absorber layers in solar cells. In the first step, we deposit a microcrystalline Si (µmc-Si:H) film <20 nm thick by sputtering a Si target in (Ar + H@sub 2@) at 230 °C. The large hydrogen flux produces µmc-Si:H with no detectable interfacial layer of amorphous silicon, due in part to subsurface implantation effects. The substrate temperature is then to 400 °C and px-Si is deposited by sputtering in Ar only. The uc-Si:H acts as a nucleation layer such that the px-Si growth reaches steady-state within 1 grain diameter; in the absence of this nucleation layer, the first 0.3-0.5 µmm of "px-Si" growth at 400 °C is amorphous silicon. We characterize the nucleation, crystallinity, and grain size of the px-Si films using real-time spectroscopic ellipsometry during growth, and using post-deposition TEM, X-ray diffraction, and Raman spectroscopy. By optimizing the growth parameters of the nucleation layer, including hydrogen partial pressure, thickness, and the use of alternating deposition and atomic hydrogen exposure, px-Si films with [110] preferred orientation and grain diameter > 400 Å can easily be obtained. We will also report preliminary electrical characterizations in both the as-deposited and post-hydrogenated states.