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.

Intrinsic stresses which arise during the chemical vapor deposition (CVD) of diamond were controlled by multistep processing. Film stresses (thermal and intrinsic) were measured with the bending plate method. The thermal stresses are compressive and arise due to the mismatch in thermal expansion coefficient between the film and substrate. The dominant intrinsic stresses are tensile and evolve during the deposition process. These stresses increase with deposition time. An intermediate step consisting of annealing the film when the diamond crystallites are only partially coalesced reduces the intrinsic stress by more than 50%. Annealing at longer growth times (i.e., after complete coalescence) does not produce large reductions in intrinsic stress. Our results are consistent with stress generation due to the formation of nonequilibrium grain boundary structures. The intermediate annealing step does not produce a large, direct stress reduction; instead, it alters the film microstructure in some subtle way which reduces stress generation during subsequent growth.

Raman spectra were measured for a series of Na2O·xZnO·ySiO2 glasses where x=O to 2 and y = 1,2, or 3. The spectra exhibit bands characteristic of sheet‐like and chain‐like strucrural units. Frequency and intensity shifts with ZnO content suggest that Zn2+ is a simple network modifier over this composition range.

Intrinsic stresses in AlN layers grown by metal organic chemical vapor deposition on (0001) sapphire and (111) Si substratesAn elastic/plastic analysis of the intrinsic stresses in chemical vapor deposited diamond films on silicon substrates Residual stress and texture in poly-SiC films grown by low-pressure organometallic chemical-vapor deposition Intrinsic tensile stresses in polycrystalline films are often attributed to the coalescence of neighboring grains during the early stages of film growth, where the energy decrease associated with converting two free surfaces into a grain boundary provides the driving force for creating tensile stress. Several recent models have analyzed this energy trade off to establish relationships between the stress and the surface/interfacial energy driving force, the elastic properties of the film, and the grain size. To investigate these predictions, experiments were conducted with diamond films produced by chemical vapor deposition. A multistep processing procedure was used to produce films with significant variations in the tensile stress, but with essentially identical grain sizes. The experimental results demonstrate that modest changes in the deposition chemistry can lead to significant changes in the resultant tensile stresses. Two general approaches were considered to reconcile this data with existing models of stress evolution. Geometric effects associated with the shape of the growing crystal were evaluated with a finite element model of stress evolution, and variations in the surface/interfacial energy driving force were assessed in terms of both chemical changes in the deposition atmosphere and differences in the crystal growth morphology. These attempts to explain the experimental results were only partially successful, which suggests that other factors probably affect intrinsic tensile stress evolution due to grain boundary formation.

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