A numerical model is presented incorporating coating thickness uniformity averaging from the double rotation of a planetary substrate fixture. The model converges on an optimal shadow mask shape much more rapidly than when using simpler empirical models, reducing the number of coating runs required. Detailed knowledge of the coating plume distribution across the planetary is not needed as the model assumes perfect averaging of the planetary motion and incorporates the measured coating flux variation across the mask. Shadow masks are designed using the model in an iterative process. With measured uniformity data from a run without any mask and from a run with a mask of known mask shape, it is shown that the desired uniformity can be obtained in a few iterations. A total thickness variation of less than 0.5 % across a four 333 mm diameter planetary is achieved in an ion beam deposition (IBD) system. Although the method is demonstrated using IBD, it is equally valid for other deposition technologies such as e-beam evaporators with a planetary fixture.
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