In situ characterization of cubic boron nitride film growth in the IR spectral region

• Published in: Thin solid films 1998-02, Vol.313 (1-2), p.697-703
• Main Authors: Barth, K.-L, Fukarek, W, Maucher, H.-P, Plass, M.F, Lunk, A
• Format: Article
• Language: English
• Subjects: Cubic boron nitride; In situ diagnostics; Polarized FTIR reflectometry; VIS ellipsometry
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(97)00980-2

Cubic boron nitride (c-BN) layers were deposited by a plasma activated process in a hollow cathode arc deposition device. The deposition process is analyzed by in situ polarized infrared reflection spectroscopy. The s-polarized infrared reflectance spectra of a growing BN film show the structure of the in-plane vibration of sp 2 bonded BN at 1370 cm −1 for film thicknesses greater than 20 nm. At thicknesses greater than 50 nm, the out of plane vibration at 780 cm −1 can be observed also. The signature of the cubic phase can be detected at a thickness of 95 nm. By simulation of the spectra, the damping constant of the c-BN oscillator was estimated to be 170 cm −1, nearly independent of the thickness. The transverse optical mode frequency of the c-BN phonon starts at 1090 cm −1, decreases to a minimum of 1070 cm −1 at a film thickness of 300 nm and increases at higher thicknesses. Up to a film thickness of 300 nm the oscillator strength increases from 5×10 5 cm −2 to 22×10 5 cm −2 and remains constant during further growth. The c-BN layer growth was investigated in situ during the variation of the DC bias voltage. At a bias voltage of −275 V a reflectance feature can be observed at 1360 cm −1 corresponding to the in-plane vibration of sp 2 bonded material.