Contributed by the Applied Mechanics Division of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS for publication in the ASME JOURNAL OF APPLIED MECHANICS. Manuscript received by the ASME Applied Mechanics Division, September 27, 2001, final revision, May 10, 2004. Associate Editor: N. Triantafyllidis.

Tejeda et al. 1 presented a new exact solution in a recent publication on a plane distortion study of the next generation ion-beam projection lithographic (IPL) masks. An IPL circular mask is supported by a relatively stiff frame and held in a vertical orientation during exposure to the ion beam 2. It is typically made of silicon of 3.0 μm in thickness and of the order of 200 mm in diameter. The problem was modeled as a clamped circular membrane loaded by in-plane gravity, and an exact plane stress solution was derived 1.

The elastic distortions due to gravitational loading are negligible in most engineering...

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