Deviation Of Film Thickness Research Articles

Flow analysis of a power-law fluid confined in an extrusion die

The one-dimensional equations in cylindrical coordinates governing flow in an arbitrary cross-sectional shape of a cavity and the slot are derived by accounting of the order of magnitude of terms by using scaling arguments and asymptotic techniques. The derived equation is based on an average momentum and mass balance within the cavity. The one-dimensional equations governing flow in a single-cavity die which can be used to predict the geometry of the cavity and the film thickness deviations for given geometry and operating points and thus yield a design strategy for extrusion die optimized for specific applications. The derived one-dimensional governing equations with the exception of coordinates system for extrusion dies are found to be identical to that of Leonard [Polym. Eng. Sci. 25 (9) (1985) 570] and Weinstein and Ruschak [AIChE J. 42 (9) (1996) 2401] who used the shape factor in the different manner and can be reduced to Miller’s [Ind. Eng. Chem. Fundam. 11 (4) (1972) 524] simple model under the certain restrictions.

Determining the Poisson’s ratio of thin film materials using resonant method

In this study, a resonant technique to characterize the Poisson’s ratio of thin film materials is proposed. The diagnostic micromachined cantilevers are fabricated using the thin film to be determined. The Poisson’s ratio of the thin film can be determined after the bending and torsional vibration modes are measured. To obtain cantilevers with prismatic cross section, the micromachined beams were fabricated on the (1 1 1) silicon substrate. The primary advantage of this technique is that the error of Poisson’s ratio due to the deviation of film thickness can be significantly reduced. In application of this technique, the Poisson’s ratio of thermally grown silicon dioxide is measured to be 0.202±0.021.

Effects of gas ring position and mesh introduction on film quality and thickness uniformity

Chromium oxide films were deposited using DC reactive magnetron sputtering system with different gas ring positions. It was found that the film quality was improved, while film thickness deviation over 2′' area of silica wafer increased, as the distance between the target and the gas ring increased. To improve both the film quality and the thickness uniformity, a method of mesh insertion was tried and verified to meet the purpose. Introduction of mesh produced stable plasma and resulted in more uniform and smooth planar film without any contamination from the mesh. These phenomena were explained in terms of gettering and scattering effects of the mesh.

Thickness deviations of films deposited by ion beam assisted deposition under off-normal ion incidence

Abstract Re-sputtering of already deposited material is a side effect of ion bombardment during film growth by ion beam assisted deposition (IBAD). This mostly undesirable effect leads to a reduction in film growth velocity. Because of this dynamic ion etching the actually deposited mass does not correspond to the evaporated mass as determined with a quartz crystal. This loss has to be accounted for by an increase in process time when a particular film thickness is required. The situation may become critical when the ion impact angle deviates from the surface normal, i.e. either when a plane substrate has to be tilted or when curved surfaces have to be coated. In the present study the deviations in film thickness are discussed for offnormal ion incidence IBAD. A mathematical expression is given which describes the dependence of the sputtering yield on the impact angle by fitting to experimentally obtained data. It is applied to calculate the dependence of film thickness deviations on the particle impact angle. As an example for coating components with a curved surface, the data for cylinders and spheres were calculated. Lengthening factors are listed for different IBAD conditions such as sputtering yield and arrival ratio of atoms and ions, which determine the excess in process time or in evaporated material necessary to coat a cylinder homogeneously with a film of a desired thickness.

Optimization of distribution chambers of coating facilities

In order to achieve coated films of constant thicknesses with coating facilities of large width, it is essential to provide well-designed distribution chambers. The present paper discusses a model equation for the flow in distribution chambers, which can be used to predict effectively both the geometry of the distribution chamber which guarantees constant film thickness for a fixed operating point of the coating facility, and the film thickness deviations for given chamber geometries and operating points. Thus, the model equations yield a design strategy for distribution chambers optimized for specific applications. A qualitative analysis of the model clarifies the mechanisms of the flow in distribution chambers. Examples of design calculations illustrate that certain simplications, which are often made by other models used to lay out distribution chambers, may lead to erroneous results.