| 摘要 |
PURPOSE:To eliminate all the pinholes by forming a light interrupting film on the side of a transparent base, subjecting it to physical washing, forming the next light interrupting film to obtain a photomask blank, and preparing a photomask by using it. CONSTITUTION:Pinholes produced or being produced in the light interrupting film formed on the side of the transparent base are forced to appear on this film by physical washing, such as ultrasonic washing, scrubbing, jet washing, surface fluidization washing, or heat washing, by using a washing liquid, such as pure water, isopropanol or the like alcohols, or other solvents. When the next light interrupting film is formed, the operation is executed while the pinholes produced through the first film are observed and disappearance of them are confirmed. The photomask is prepared by patterning 2 or more light interrupting films from this photomask blank, thus permitting perfect elimination of pinholes. |
