| 摘要 |
<p>PURPOSE:To obtain the cover for protection of a photomask by providing a thin film having a uniform thickness on a substrate and stripping the film in water to form the thin film, fixing the film in the half-dried state uniformly to a supporting frame and drying the film. CONSTITUTION:The film having no orientability is formed by a casting system using cellulose ester. The cellulose ester dissolves easily in relatively low boiling solvents such as ketone and the finish thickness can be controlled to a prescribed thickness by regulating the soln. concn. and casting thickness. The thickness of 2.8+ or -0.3mum, etc., are used for the protective film. The thin film peels naturally when a smooth glass plate is used for the casting substrate and is immersed into water after the solvent removal. The thin film is supported in the uniformly tensed state to the Al supporting frame by placing the film in the half-dried state directly to the supporting frame and coating a volatile solvent along the contact part of the film and the frame and drying the coating. The thickness of the supporting frame functions as a spacer.</p> |
