| 摘要 |
PURPOSE:To produce an optical mask having fine positive type patterns by making combination use of electron beam exposure techniques capable of making fine working and dry etching of good selectivity. CONSTITUTION:A Si light shield film 4 of a sufficient thickness is provided on a glass substrate 5, and positive type resist PBS of a high rate of dry etching but of a high resolving power is spin-coated thereon and is then baked. Desired positive type patterns 1 are created by performing exposure and development. Next, the surface is covered with optical resist 3 of a rate of dry etching smaller than that of PBS, then serrations are greater at the pattern edge. Next, the surface is sputter etched by CF4. If OMR-83 is used for the resist 3, the OMR-83 of the surface is first etched because its rate of etching is 1/15 that of PBS. When PBS exposues, PBS is etched extremely fast and the remained patterns become the negative patterns of OMR-83. When etching is done further, desired fine positive patterns of the film 4 may be readily formed. |
