Patent ID: 11892768
Assignee: HOYA CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 11:
12. A reflective mask comprising:
a substrate;
a multilayer reflective film provided on the substrate; and
an absorber film provided on the multilayer reflective film and having a patterned absorber pattern,
wherein the absorber film comprises:
a high absorption coefficient element selected from the group consisting of cobalt (Co) and nickel (Ni), and
an element that increases a dry etching rate, and

wherein a lower surface region of the absorber film includes a surface of the absorber film that faces the substrate and an upper surface region of the absorber film includes a surface of the absorber film that faces away from the substrate, and
wherein a concentration (atomic %) of the high absorption coefficient element in the upper surface region is higher than a concentration (atomic %) of the high absorption coefficient element in the lower surface region, and
wherein the absorber film optionally includes both of Co and Ni,
wherein the concentration of the high absorption coefficient element decreases monotonically from the upper surface region to the lower surface region in a depth direction of the absorber film, and
wherein a concentration of the element that increases the dry etching rate increases monotonically from the upper surface region to the lower surface region in the depth direction of the absorber film.