Journal of Materials Research

Articles

Characterization of boron nitride thin films prepared from a polymer precursor

V. Z-H. Chana1, J. B. Rothmana2, P. Palladinoa3, L. G. Sneddona4 and R. J. Compostoa5

a1 Laboratory for Research on the Structure of Matter, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104

a2 Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104

a3 Laboratory for Research on the Structure of Matter, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104

a4 Laboratory for Research on the Structure of Matter, and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104

a5 Laboratory for Research on the Structure of Matter, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104

Abstract

Excellent quality boron nitride (BN) thin films on silicon have been produced by a simple procedure involving spincoating solutions of the “single-source” polymeric-precursor polyborazylene, (B3N3H∼4)x, on a silicon substrate, followed by pyrolysis at 900 °C. Rutherford backscattering spectrometry (RBS) indicates that the B/N ratios are 1.37 and 1.09 for conversions carried out in a vacuum oven at 900 and 1250 °C, respectively. Forward recoil spectrometry (FRES) showed that the atomic percent of residual hydrogen is 10 and 9%, respectively. Plain-view and cross-sectional scanning electron microscopy (SEM) studies showed that the samples annealed at 900 °C were clean and uniform in thickness. A thickness of 800 × 1015 atoms/cm2 was determined by ion scattering. Films annealed to 1250 °C likewise showed a continuous unbroken boron nitride layer, but also exhibited morphological features resulting from reactions of the underlying silicon oxide-silicon interface in the substrate. Auger electron spectroscopy and atomic force microscopy showed that the BN coating produced at this higher temperature remained unbroken but had a surface area of ∼15% covered by dimples 2–7 nm in depth. Compared to typical films made by chemical vapor deposition, BN films produced from this “single-source” method have lower hydrogen and carbon concentrations.

(Received July 10 1995)

(Accepted October 10 1995)

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