Stress control and etching study of W-Re as X-ray mask absorber

Stress control and etching of Tli-Re as X-ray mask absorber was studied. The W-Re film was deposited using an rf magnetron sputtering apparatus with two material targets, The substrates were revolved by themselves and over the W and Re targets to achieve uniform film thickness and stress. When the content ratio of W to Re was 1:1, non-columnar film structure was obtained. The stress repeatability, when the deposited film stress is near zero, was +/- 5 x 10(8) dyn/cm(2). To further control the stress, implantation of Ar ions was carried out with an acceleration voltage of 180 kV. The stress change was 1 x 10(9) dyn/cm(2) compressive at the ion dose of about 6 x 10(15) ions/cm(2). The etching of W-Re was carried out using SF6 and CHF3 gas mixture and a Cr etching mask by applying magnetron reactive ion etching. The etching selectivity between W Re and Cr was over 250 in the CHF3 content below 60%. We applied two-step etching to remove etch-obstructing films on the W Re surface, and fabricated 0.1 mu m lines and spaces of 0.5-mu m-thick W-Re film.