Amorphous refractory compound film material for X-ray mask absorbers

We proposed that the stress of the side walls of an absorber pattern causes the pattern distortion of an X-ray mask. The surfaces of the pattern side walls have a high compressive stress layer because they are easily oxidized in air after absorber pattern etching. This stress becomes a serious problem in proportion to the high degree of pattern integration. To lower the surface oxide layer stress of the film, we developed a TaGe nitride (TaGeN) absorber. The oxide layer stress of TaGeN films becomes lower with increasing the N-2 content in the sputtering gas, and the stress value of Ta0.35Ge0.20N0.45 can be decreased to 1/17 that of TaGe. We fabricated a TaGeN X-ray mask and practically demonstrated that the TaGeN absorber was effective for high image placement accuracy to an X-ray mask having high dense patterns with a 0.1 mu m pattern size.