Benzophenone‐containing methylthiomethyl pendant polyimides as negative acting photoresists

摘要

AbstractFour kinds of benzophenone‐containing polyimides, each of which carries different amount or distribution of methylthiomethyl (MTM) pendant groups, are applied as negative photoresists. Lithographic evaluation of these polyimides shows that PI‐42, the polyimide possessing the most, i.e., three MTM groups in a repeating unit on average, exhibits the highest sensitivity (D g0.5= 129 mJ/cm2), the highest contrast value (γ = 4.3), and the highest resolution capability (1.2‐μm lines and spaces can be resolved in a 1.0 μm thick film). In the air, the photopatterned lines obtained from all these polyimides are thermally stable up to 280°C. Upon treating at 400°C for 30 min, a 8% reduction in the linewidth is observed for the 3.8‐μm line of PI‐42. The optimum developing conditions of each of these title polymers are determined. Contrast curve analysis indicates that this resist system exhibits higher sensitivity at near UV region than at deep UV region. © 1993 Jo