Method of making an oxide structure having a finely calibrated thickness

Abstract

A process of growing silicon oxide to a highly calibrated thickness is provided. In one embodiment, a silicon precursor material is deposited to a first thickness on a substrate, such as a fused glass substrate used for forming microlithography masks. The precursor material is then selectively exposed to ionization and the non-ionized portions of the precursor material are then selectively etched leaving only the implanted portion of the precursor material of the first thickness. The implanted material is then oxidized resulting in an oxide structure having a thickness that is directly correlated to the initial thickness and the coefficient of oxidation. In one embodiment, a selective etch, such as TMAH, is used to remove unimplanted silicon which results in less than one percent etching of the implanted silicon. Hence, the process can be used to form phase shift structures on phase shift photolithography masks wherein the thickness of the phase shift structure can be formed to within a specific tolerance to achieve a desired phase shift of light traveling through the phase shift structure.

Dependencies are inferred from the claim text.