J. Priest

Bio: J. Priest is an academic researcher from IBM. The author has contributed to research in topics: Partial pressure & Stress (mechanics). The author has an hindex of 3, co-authored 3 publications receiving 130 citations.

Low-Temperature Properties of Evaporated Lead Films

Abstract: Lead films have been deposited onto room‐temperature substrates having low thermal expansion coefficients and the residual mechanical stresses present in these films have been determined as a function of film thickness and film purity. At room temperature no measurable stress (<5×107 dyn/cm2) was present in any film. At 78° and 4.2°K the stress σ was given by σ=α+β/d, where α is a constant dependent on temperature and d is the film thickness. A model involving surface pinning of dislocations predicts an equation of this form, but the experimental values for the stress were found to be appreciably larger than values calculated on the basis of bulk data. The experimental values were substantiated by superconducting critical temperature measurements on films of various thicknesses. Localized crystalline growth was observed in lead films after cooling to 4°K. The film material around these micron‐size crystals exhibiting five‐ and sixfold rotational symmetry was thinned to the point that physical holes were e...

Stress Anisotropy in Silicon Oxide Films

Abstract: The residual stress in films formed by vacuum sublimation of bulk silicon monoxide has been studied as a function of the angle of incidence of the evaporant. Using a source temperature of 1350–1400°C and a system total pressure of ∼2×10−6 Torr, a pronounced dependence of stress on angle of incidence and a distinct stress anisotropy was observed. The stress in the x direction (i.e., perpendicular to the direction of the evaporant irrespective of substrate orientation) increases from 4×108 dyn/cm2 for normal incidence to 14×108 dyn/cm2 for an incident angle of ∼50° and then decreases to 4×108 dyn/cm2 for an incident angle of 80°. The stress in the y direction (i.e., perpendicular to the x direction) is peaked at ∼30° at a value of 13×108 dyn/cm2 and then decreases to ∼0.5×108 dyn/cm2 at 80°. Films formed at normal incidence are quite stable and not susceptible to the effects of water vapor. However, films formed by depositing at grazing incident angles (>30°) are very unstable and invariably buckle and rupture when exposed to atmospheres of water vapor. Substrate temperature, film thickness, and inert residual gases were found to have little effect on the stress and stability of films deposited at an angle of incidence of 45°. When a lower source temperature (<1200°C) is used and a high partial pressure (10−4 Torr) of water vapor is present during deposition, the resulting highly oxidized films show a compressive stress (∼2×108 dyn/cm2) and very little dependence on the angle of incidence. These films are stable when exposed to higher partial pressures of water vapor.

Intrinsic stress in sputter-deposited thin films

Abstract: A review of the sputtered film stress literature shows that the intrinsic stress can be tensile or compressive depending on the energetics of the deposition process. Modeling studies of film growth and extensive experimental evidence show a direct link between the energetics of the deposition process and film microstructure, which in turn determines the nature and magnitude of the stress. The fundamental quantities are the particle flux and energy striking the condensing film, which are a function of many process parameters such as pressure (discharge voltage), target/sputtering gas mass ratio, cathode shape, bias voltage, and substrate orientation. Tensile stress is generally observed in zone 1-type, porous films and is explained in terms of the grain boundary relaxation model, whereas compressive stress, observed in zone T-type, dense films, is interpreted in terms of the atomic peening mechanism. Modeling of the atomic peening mechanism and experimental data indicate that the normalized moment...

Stresses and deformation processes in thin films on substrates

Abstract: The stresses that develop in thin films on substrates can be detrimental to the reliability of thin film electronic devices. In order to design these devices for improved mechanical reliability, an...

Thin film retardation plate by oblique deposition

Abstract: The birefringent property of obliquely deposited metal oxides was studied with a view to applying it to optical retardation plates. By finding favorable conditions to form transparent films of large retardation and low opacity, we developed homogeneous quarterwave plates with a bilayered structure 60 x 250 mm in size and ~3 microm thick on glass substrates. These retardation plates can work with a normally incident light based on form birefringence caused by the characteristic anisotropic microstructure inside the film. They showed promising optical properties which can compete with the conventional types of retardation plate.

Intrinsic stress in diamond films prepared by microwave plasma CVD

Abstract: The stress in diamond films prepared by microwave plasma CVD was investigated as a function of methane concentration (0.2%–3.0%) and deposition temperature (600–900 °C). Tensile and compressive total (thermal and intrinsic) stress were observed, depending on the deposition conditions. The thermal stress is compressive and relatively constant (0.215–0.275 GPa) over the temperature range investigated. The intrinsic stress is tensile and its origin is interpreted in terms of the grain boundary relaxation model. Calculations indicate a value of 0.84 GPa, using the grain boundary model, which is in fair agreement with the measured value. For the methane series, the tensile intrinsic stress decreases with increasing the methane fraction. The increasing compressive stress is ascribed to increased impurity (hydrogen and nondiamond phase carbon) incorporation with increasing methane fraction. 15N nuclear reaction analysis shows a linear correlation between hydrogen in the film and methane in the supply gas while spectroscopic ellipsometry shows a direct correlation between optically absorbing nondiamond (sp2) carbon incorporation and methane. For the temperature series, the intrinsic tensile stress increases with deposition temperature. The increase is ascribed to decreasing sp2 C incorporation with temperature, as confirmed by spectroscopic ellipsometry measurements.