LOW STRESS TUNGSTEN VAPOR DEPOSITION

摘要

X-ray masks are typically made by depositing and patterning a layer of heavy metal on a thin supporting membrane. The metal layer must have a relatively low and uniform stress to prevent stress-induced deformation of the pattern. Tungsten films having excellent stress characteristics are produced by employing a continuously operating capacitance-based measurement technique to allow adjustment of the deposition conditions in rapid response to changes in stress of the film being deposited. The stress gradients in the film are further reduced by introducing a gas onto the backside of the membrane as the tungsten is formed on the front side, thereby transferring heat from the membrane as the metal is deposited thereon.