| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a master disk of an optical disk in which a land pre-pit(LPP) and its adjacent grooves have a shape not affecting reproduced signals when pits and grooves of different depths are formed on the same master disk by using plasma etching and ashing processes. SOLUTION: The LPP is formed between shallow grooves or between shallow pits with the use of laser having power smaller than that of laser for forming the shallow grooves or shallow pits, and thus the depth of the LPP region and its adjacent groove regions and the depth of the surrounding grooves are made, after passing through the etching and ashing processes, equal.
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