Session: DP-1 |
Low-Stress, Adherent Cubic Boron Nitride Films with Oxygen Addition |
Abstract # 32 |
Author(s) |
Presenter |
Correspond |
J. Ye; Forschungszentrum Karlsruhe, IMF I, Germany |
X |
X |
S. Ulrich; Forschungszentrum Karlsruhe, IMF I, Germany |
|
|
C. Ziebert; Forschungszentrum Karlsruhe, IMF I, Germany |
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Abstract:
Well-adhered, low-stress cubic boron nitride (c-BN) films were
successfully grown on to silicon substrates by means of controlled addition of
oxygen into the films. The deposition was based on the radio-frequency
magnetron sputtering of a hexagonal boron nitride (h-BN) target, and was
accomplished in a reactive mode using gas mixtures of argon/nitrogen/oxygen at
0.3 Pa pressure, 400 °C growth temperature, and -250 V substrate bias. In the
present study, systematic results are shown with respect to the critical
influences of oxygen partial pressure during deposition upon the stress, cubic
phase fraction, as well as nanohardness of the deposited films. Although the
formation of c-BN was completely hindered at oxygen fractions above 1.5 vol.%
in the gas mixture, there existed only marginal influences on the c-BN
fraction, yet strong impact on the film stress on the other hand, when limiting
the oxygen content within 1 vol.%. Cubic-phase dominated films (containing
70~80 vol.% c-BN) with their compressive stress three times reduced were thus
produced through careful control of oxygen partial pressure, showing an
excellent plastic hardness of almost 60 GPa. For such films, a post-deposition
thermal treatment at 900 °C was found to bring about an additional drastic
stress relaxation leading to an ultimate stress that is almost 10 times lower
than that of as-deposited c-BN films without intentional oxygen addition.
Furthermore, owing to the reduced film stress, adherent, µm-thick c-BN films
were achieved, with an adequate buffer layer, on to silicon substrates.
Note: Requested a Poster Session.