Mechanical properties of amorphous and microcrystalline silicon films

• Published in: Thin solid films Vol. 516; no. 16; pp. 5368 - 5375
• Main Authors: Kulikovsky, V., Vorlíček, V., Boháč, P., Stranyánek, M., Čtvrtlík, R., Kurdyumov, A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 30.06.2008; Elsevier Science
• Subjects: a-Si films; Compressive stress; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Elastic modulus; Exact sciences and technology; Hardness; Materials science; Mechanical and acoustical properties; Methods of deposition of films and coatings; film growth and epitaxy; Physical properties of thin films, nonelectronic; Physics; Raman spectra; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Elastic modulus; Raman spectra; Compressive stress; a-Si films; Hardness; Vacuum annealing; Phase transformations; Electron diffraction; Mechanical properties; Raman spectroscopy; Layer thickness; Indentation; Thin films; Cathode sputtering; Physical vapor deposition; Stress effects; Silicon; Sputter deposition; Microstructure; Crystal structure
• DOI: 10.1016/j.tsf.2007.07.047
• ISSN: 0040-6090

Hydrogen-free amorphous silicon (a-Si) films with thickness of 4.5–6.5 μm were prepared by magnetron sputtering of pure silicon. Mechanical properties (hardness, intrinsic stress, elastic modulus), and film structure (Raman spectra, electron diffraction) were investigated in dependence on the substrate bias and temperature. The increasing negative substrate bias or Ar pressure results in simultaneous reducing compressive stress, the film hardness and elastic modulus. Vacuum annealing or deposition of a-Si films at temperatures up to 600 °C saving amorphous character of the films, results in reducing compressive stress and increasing the hardness and elastic modulus. The latter value was always lower than that for monocrystalline Si(111). The crystalline structure (c-Si) starts to be formed at deposition temperature of ∼ 700 °C. The hardness and elastic modulus of c-Si films were very close to monocrystalline Si(111). Phase transformations observed in the samples at indentation depend not only on the load and loading rate but also on the initial phase of silicon. However, the film hardness is not too sensitive to the presence of phase transformations.