Patent ID: 8431004

Claim:
A method of making a stamper that has a fine uneven surface structure, the method comprising the steps of: (a) providing a base, of which a surface has an aluminum layer including at least 95 mass % of aluminum; (b) anodizing the aluminum layer partially, thereby forming a porous alumina layer with a plurality of recessed portions; and (c) bringing the porous alumina layer into contact with an alumina etchant to expand the recessed portions of the porous alumina layer, wherein a plurality of recessed portions, each having a stepped side surface, are formed on the porous alumina layer by alternately and repeatedly performing the steps (b) and (c) a number of times, wherein one or more of the recessed portions are surrounded with three to six pointed raised portions, and wherein a plurality of saddle portions, which are different from the plurality of raised portions and the plurality of recessed portions, are between the tops of adjacent raised portions, each saddle portion interconnecting the tops of two adjacent raised portions, wherein the each saddle portion having, at the midpoint of the tops of two adjacent raised portions, a smaller height than the raised portions.