Wafer location integrity in aluminum metallization

Abstract

Aluminum sticking between wafer and clamp ring is unavoidable during metallization. The non-concentric location of the wafer on the clamp ring may result in awkward drop-off after sputtering; resulting in damage to the wafer. An existing hoop lift and clamp ring design to locate the wafer during sputtering was deemed not to adequately meet complete constraint requirements in relation to kinematic positioning principles. A prototype model hoop lift and clamp ring design that met these requirements was fabricated. In a verification experiment, an optical planar displacement sensing method was used to ascertain the location integrity of the two designs via a repeated placement test. The prototype model hoop lift and clamp ring design was shown to exhibit significantly improved levels of location integrity compared with the original design. © 2004 Elsevier B.V. All rights reserved.