| 摘要 |
PURPOSE:To produce a uniform photomask with good reproducibility for an optical memory element by adding an etching process and a photoresist removing process to a well-known production method. CONSTITUTION:A thin film 2 comprising Cr, Ti, etc., is formed to 300-1000Angstrom thickness on a photomask substrate 1, and further a positive photoresist film 3 is formed thereon to 1000-4000Angstrom thickness and prebaked at about 95 deg.C. Then two Ar laser light beams are condensed to expose the photoresist film 3 in a spiral trace while rotating the substrate once. One laser beam 4 is used to expose format pits 1a and the other laser beam 5 is used to expose guide tracks 1b. After exposing, the photomask is developed, postbasked, and etched till the thin film 2 in the pit part 1a becomes 10-200Angstrom thick. Then, the resist film 3 is removed till the thin film 2 in the guide tracks 1b appears, and the photomask is dry etched till the thin film 2 in the pit part 1a is completely removed and the substrate appears. Then the remaining photoresist is removed by ashing treatment. |
