Phase and Microstructure Investigations of Boron Nitride Thin Films by Spectroscopic Ellipsometry in the Visible and Infrared Spectral Range

E. Franke, M. Schubert, H. Neumann
Institut für Oberflächenmodifikation
Permoserstraße 15
D-04303 Leipzig
Germany

T.E. Tiwald, D.W.Thompson, J.A. Woollam
University of Nebraska-Lincoln
Center for Microelectronic and Optical Materials Research, and Department of Electrical Engineering
Lincoln, Nebraska 68588

J. Hahn, F. Richter
Technische Universität Chemnitz, Institut für Physik
Technische Physik / Physik fester Körper
D-09107 Chemnitz
Germany

Spectroscopic ellipsometry over the spectral range from 700 cm^-1 to 3000 cm^-1 and from 1.5 eV to 3.5 eV is used to simultaneously determine phase and microstructure of polycrystalline hexagonal and cubic boron nitride thin films deposited by magnetron sputtering on (100) silicon. The results are obtained from a single microstructure-dependent model for both infrared and visible-light thin-film anisotropic dielectric functions. The optical behaviour of high c-BN content thin films is described by an effective medium approximation. We obtained the amount of h-BN within high c-BN content thin films. A thin oriented nucleation layer between the silicon substrate and the high c-BN content layer is demonstrated. The preferential arrangement of the grain c-axis within the h-BN thin films are found to be dependent on the growth parameters. The results from the infrared and visible spectral range ellipsometry model are compared to each other and found to be highly consistent.