To obtain a multilevel binary optical device of high accuracy.
The optical device is manufactured by subjecting a substrate on which a photosensitive resist film is formed to multiple exposure by using a plurality of masks, then developing the substrate to form a resist layer having different film thickness in a plurality of levels according to the quantity of exposure light, and etching to form a multilevel binary three-dimensional shape on the substrate. In this method, the process of multiple exposure is carried out in two steps: a step of base exposure to expose the whole region where the three-dimensional shape is to be formed to the quantity (A) of base exposure light, wherein (A) is the quantity of light equal to or larger than the minimum quantity of exposure light which gives almost linear relation between the quantity of exposure light on the resist film and the residual film rate of the resist film after development, and a step of multiple exposure to separately expose the film where the three-dimensional shape is to be formed to the quantity of light (B)-(A), wherein (B) is the quantity of exposure light corresponding to the final residual film residual rate.
TOYAMA KIYOSHI
KONUKI TETSUJI
