Extension of the one-dimensional Stoney algorithm to a two-dimensional case
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This article presents the extension of the one-dimensional Stoney algorithm to a two-dimensional case. The proposed extension consists in modifying the method of curvature estimation. The surface profile of the wafer before deposition of the thin film and after its deposition was locally approximated by the quadric. From this quadric, a quadratic form and the first degree surface were separated. An eigenproblem was solved for the matrix of this quadratic form. From eigenvectors a new coordinate system was created in which a new formula of the quadric was found. In this new coordinate system, the two-dimensional problem of estimating the curvature tensor has been solved by solving two independent one-dimensional problems of curvature estimation. Returning to the primary coordinate system, in this primary coordinate system, a solution to the two-dimensional problem was obtained. The article proposed five versions of the two-dimensional Stoney algorithm, with diverse complexity and accuracy. The recommendation for the version of the algorithm that could be practically used was also presented.
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