Mold for cast molding of substrate for information recording medium, method for preparing substrate for information recording medium and method for preparing information recording medium by use thereof.

摘要

A mold (3) for cast molding of a substrate for information recording medium (5) has an uneven preformat pattern, wherein said uneven preformat pattern formed on the mold surface has at least a pattern corresponding to tracking grooves (1) and information pits (2), each information pit portion has a size with a length b in the direction parallel to the pattern of the tracking groove (1) of 2 to 15 mu m and a width a in the direction perpendicular thereto of 1 to 6 mu m and a height c of 300 to 3500 ANGSTROM , and said pit pattern has a pitch which is 1.8-fold or more of said pit length b. A method for preparing a substrate for information recording medium (5) having an uneven preformat uses a mold (3) for cast molding which is characterized in that an uneven preformat pattern corresponding to said uneven preformat formed on the mold surface has at least a pattern corresponding to tracking grooves (1) and information pits (2), each information pit portion (2) has a size with a length b in the direction parallel to the pattern of the tracking groove of 2 to 15 mu m and a width a in the direction perpendicular thereto of 1 to 6 mu m and a height c of 300 to 3500 ANGSTROM , and said pit pattern has a pitch which is 1.8-fold or more of said pit length b. A method for preparing an information recording medium (5) comprises the following steps: the step of preparing a substrate for information recording medium (5) on which uneven preformat with at least tracking grooves (1) and information pits (2) is formed by use of a mold for cast molding (3), said mold for cast molding (3) having an uneven preformat pattern corresponding to said uneven preformat formed on the mold surface, the information pit portion (2) of said uneven preformat pattern having a size of a length b of 2 to 15 mu m and a width a of 1 to 6 mu m and a height c of 300 to 3500 ANGSTROM , and said pit pattern having a pitch which is 1.8-fold or more of said pit length b; and the step of forming a recording layer on said substrate for information recording meidum (2).