Abstract
Thick resist patterning process using liquid-crystal-display (LCD) matrix exposure is demonstrated. Because LCD panels have sufficient contrast between dark and bright cells only for light with wavelengths of longer than 430 nm, resists sensitive to ultra violet (UV) light cannot be directly patterned. For this reason, multi-layer resist structure of OFPR 800/aluminum/SU-8 is developed. After patterning OFPR 800/aluminum using the LCD matrix exposure by light with a central wavelength of 450 nm, patterns are inversely replicated to SU-8 by a flood exposure of UV light. In the initial research stages, a lot of wrinkles and cracks are formed in the aluminum film by the pre-bake process of OFPR 800. However, no-bake vacuum treatment process is contrived, and the defects of SU-8 caused by the excessive exposure through the aluminum cracks are completely prevented. Stable patterning process of thick SU-8 using LCD matrix exposure is certainly established.
