Characteristics of Ta-based amorphous alloy film for x-ray mask absorbers

We examined Ta-based amorphous alloy films and studied their characteristics for application in an x-ray mask with dimensions of the 0.1 μm design rule. From the viewpoint of x-ray absorption, Ge is a suitable element for a compound with Ta. We found that a Ge inclusion atomic ratio of 20%–30% in a Ta–Ge compound film was suitable with respect to stress control and stress stability. It was possible to adjust the stress of the Ta–Ge film after deposition by annealing it at high temperature while maintaining control as good as 0.56 MPa/ °C. During pattern fabrication by dry etching, it was possible to successfully etch the Ta–Ge film with a single-layer resist using a chroline based plasma, and scale patterns of 0.1 μm were obtained.