A NEW OPERATING REGIME FOR ELECTROPLATING THE GOLD ABSORBER ON X-RAY MASKS

A new technique for more repeatably and more controllably electroplating gold films for use as the absorber on x-ray masks is presented. Films electroplated from a gold-sulfite based bath containing high concentrations of thallium-based brightener possess low stresses (< 20 MPa) that can be further tailored by varying other plating parameters, such as temperature and current density. Grain size was found to be uniform and on the order of about 2000 Angstrom, suitable for repair via a technique such as focused ion beam HB) milling. With a peak to valley surface roughness of about 330 Angstrom and a low ''nuisance'' defect density, the films were shown to be inspectable down to 0.04 mu m.