| 摘要 |
PROBLEM TO BE SOLVED: To stably form a groove pattern which is thinner than the spot diameter of an exposure beam through a simple process. SOLUTION: A mask layer is formed in double-layered structure by laminating a 1st mask layer 3 and a 2nd mask layer 4 on the surface of a lower layer 2 formed of water-soluble resin on a glass substrate by using photoresist materials and when the groove pattern 11 is formed by exposing the mask layer to a laser beam 8 and developing it, the formed groove pattern 11 is prevented from varying in height owing to repetitive exposure to the edge of the exposure beam. A groove pattern 12 is formed on the lower layer by etching an exposed part of the lower layer 1 by using the mask layer having the fixed-height groove pattern 11 as a mask, so that the groove pattern 12 which has uniform height is precisely formed on a glass original disk 13.
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