| 摘要 |
PURPOSE:To effect a pattern alignment of a mask even if the step difference of a film thickness may be slight by making use of the interference of a light in the thin film. CONSTITUTION:When a light of wavelength of lambda is projected to a thin film having a thickness d and a defractive rate n, the interference of the light is canceled if 2d=(2k-1/2).lambda/n. cap. When the light with the wavelenght lambda1 is projected to a portion A with the thickness d1 of an oxidization film 2, the portion A is turned to black color, but any interference is not caused in a portion B and the light with the wavelength lambda1 is appeared only. Therefore, a pattern alignment for a mask 4 can be performed. The light having an appropriate wavelength can be obtained by inserting a colored glass before a white light source. According to this construction, the desirable pattern alignment capable of discrimination cna be established by making use of the interference due to a signal color light even if the discrimination of the film surface can not fully made due to the surface step. |
