Method for producing mold and electrode structure used therefor

A method of fabricating a mold that has an inverted motheye structure in its surface, the inverted motheye structure having a plurality of recessed portions whose two-dimensional size viewed in a direction normal to the surface is not less than 10 nm and less than 500 nm, the method comprising the steps of:

• (a) anodizing a surface of an aluminum film or aluminum base via an electrode that is in contact with the surface, thereby forming a porous alumina layer which has a plurality of very small recessed portions;
• (b) after step (a), allowing the porous alumina layer to be in contact with an etchant, thereby enlarging the plurality of very small recessed portions of the porous alumina layer;
• and
• (c) after step (b), further anodizing the surface via the electrode to grow the plurality of very small recessed portions,
• wherein part of the electrode which is in contact with the surface is made of aluminum whose purity is 99.99 mass % or higher or a metal whose standard electrode potential is lower than that of aluminum.

An electrode structure for use in a method of fabricating a mold that has an inverted motheye structure in its surface, the inverted motheye structure having a plurality of recessed portions whose two-dimensional size viewed in a direction normal to the surface is not less than 10 nm and less than 500 nm, the method comprising the steps of

• (a) anodizing a surface of an aluminum film or aluminum base via an electrode that is in contact with the surface, thereby forming a porous alumina layer which has a plurality of very small recessed portions,
• (b) after step (a), allowing the porous alumina layer to be in contact with an etchant, thereby enlarging the plurality of very small recessed portions of the porous alumina layer, and
• (c) after step (b), further anodizing the surface via the electrode to grow the plurality of very small recessed portions,
• the electrode structure comprising:
• the electrode which has an elevated portion that is made of aluminum or a metal whose standard electrode potential is lower than that of aluminum;
• a mechanism of pressing the elevated portion of the electrode against the surface of the aluminum film or the aluminum base;
• and
• a protection member arranged to surround a perimeter of the elevated portion of the electrode, the protection member being in contact with the surface even when the elevated portion is not in contact with the surface such that a gap between the surface and the elevated portion can be tightly closed.