Reflective mask blank, reflective mask and methods of producing the mask blank and the mask

摘要

A reflective mask blank has a substrate (11) on which a reflective layer (12) for reflecting exposure light in a short-wavelength region including an extreme ultraviolet region and an absorber layer (16) for absorbing the exposure light are successively formed. The absorber layer (16) has an at least two-layer structure including as a lower layer an exposure light absorbing layer (14) formed by an absorber for the exposure light in the short-wavelength region including the extreme ultraviolet region and as an upper layer a low-reflectivity layer (15) formed by an absorber for inspection light used in inspection of a mask pattern. The upper layer is made of a material containing tantalum (Ta), boron (B), and nitrogen (N). The content of B is 5 at% to 30 at%. The ratio of Ta and N (Ta : N) falls within a range of 8 : 1 to 2 : 7. Alternatively, the reflective mask blank has a substrate on which a multilayer reflective film and an absorber layer are successively formed. In this case, the absorber layer is made of a material containing tantalum (Ta), boron (B), and nitrogen (N). The content of B is 5 at% to 25 at%. The ratio of Ta and N (Ta : N) falls within a range of 8 : 1 to 2 : 7.