METHOD OF SHAPING A FLEX MASK FOR USE IN UNIFORM OPTICAL COATING BY ION BEAM SPUTTERING

摘要

A method of generating a mask for use in an ion beam sputtering system for coating oxides on a plurality of mirrors located on a rotating platen. The mask reduces non-uniformity of the oxide coating the mirrors in a radial directio n from the platen axis of rotation. The shape of the mask is derived from a test run of the coating thickness on a stationary glass plate having the same area as the platen. Th e resulting coating thickness on the glass plate is measured by an ellipsometer as a function of position. The measured coating thickness is mapped to produce a correspondin g flux pattern. A coating rate map is then determined by dividing coating thickness by coating time. The functional form of the mask is determined in width along a radial distance of the platen. The coating rate for a predetermined radial distance is obtained by adjusting angular width of the mask, which blocks a portion of the flux radially and angularly, until the desired average coating rate is obtained for that radial distance. After all the radial distances or bands have been assigned their desired angular widths, the function form of the mask is determined.