Stress evolution in nanocrystalline diamond films produced by chemical vapor deposition

Abstract

Nanocrystalline diamond films were grown on silicon substrates by microwave plasma enhanced chemical vapor deposition with 1% methane, 2%-10% hydrogen, and argon. High resolution transmission electron microscope images and selected area electron diffraction patterns confirm that the films consist of 10-20 nm sized diamond grains. The residual and intrinsic stresses were investigated using wafer curvature. Intrinsic stresses were always tensile, with higher H 2 concentrations generally leading to higher stresses. Annealing the films in a hydrogen plasma significantly increased these stresses. These hydrogen induced changes also appear to alter stress levels and stress gradients during the growth process itself. Raman spectra revealed subtle changes in the chemical bonding that were correlated with some of the stress variations. These results suggest that grain boundary bonding and hydrogen induced reactions at the grain boundaries can influence the intrinsic stresses in nanocrystalline diamond films.

Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion

“…These columnar secondary structures were formed by the growth and rearrangement of nanosized diamond crystallites resulting from the ultra high-rate nucleation of carbon dimers in plasma. 13,14 The secondary structures in the NCD coatings resulted in increased roughness of the NCD coated titanium compared to the titanium substrate, as listed in Table I. Higher H 2 concentration in the plasma when depositing NCD also resulted in higher roughness values for the NCD-coated titanium, confirming results from 3D surface morphology results obtained from AFM (Fig.…”

“…The formation of NCD on titanium substrates was also suggested by the Raman spectra of each sample shown in Figure 3. All the spectra revealed the typical peaks of NCD reported by others 13, 14. Specifically, the broad peak at 1330 cm −1 observed in all of the NCD‐coated samples was the characteristic peak of diamond which was possibly broadened due to the reduced grain sizes in NCD 15.…”

“…All the spectra revealed the typical peaks of NCD reported by others. 13,14 Specifically, the broad peak at 1330 cm À1 observed in all of the NCD-coated samples was the characteristic peak of diamond which was possibly broadened due to the reduced grain sizes in NCD. 15 Although there have been disputes that the 1330 cm À1 peak originates from the D-band stretching of the large amount of sp 2 carbon at NCD boundaries rather than sp 3 carbon in diamond, the Raman results reported here are consistent with previous results of NCD confirmed by supplementary characterization such as SEM and transmission electron microscopy.…”

“…All of the NCD coatings on titanium showed secondary structures which were composed of nanosized crystals and had three dimensional column shapes with sizes up to 2 μm. These columnar secondary structures were formed by the growth and rearrangement of nanosized diamond crystallites resulting from the ultra high‐rate nucleation of carbon dimers in plasma 13, 14. The secondary structures in the NCD coatings resulted in increased roughness of the NCD coated titanium compared to the titanium substrate, as listed in Table I.…”

Impact of Surface Chemistry on Grain Boundary Induced Intrinsic Stress Evolution during Polycrystalline Thin Film Growth

“…Here, quenching from low temperature should lead to less hydrogen abstraction. This behavior is also nominally consistent with previous experimental evidence which shows that plasma annealing at 800 C decreases the H content at the GB and increases the tensile stress [25]. The trend in Eq.…”