Developments of Multilayer Resist Technology for the Halftone Mask

Abstract

When the halftone mask is used in the lithography process in LCD manufacturing, the manufacturing process number is reduced. By the use of the halftone mask, the exposure dose to the resist is adjusted, and three kinds of resist film thickness are produced. However, the resist is exposed in the part in which the sensitivity curve rises. When the exposure dose to the resist fluctuated slightly, the resist film thickness drastically fluctuated. This time, we used two kinds of the resist that have different sensitivities. The lower layer resist has low sensitivity and the upper layer resist has high sensitivity. Though we applied two resists which optimized the bake condition, the horizontal part was not obtained. We thought that the two resists may have mixed. We added a water-soluble intermediate layer film between two resists, and then it became possible to eliminate the variation of the resist film thickness due to the slight variation of the exposure dose.