Photosensitive polynorbornene as a dielectric material for packaging applications

The rapid development of the microelectronics industry creates high demand for low dielectric constant (low-k) materials. Polynorbornene (Avatrel/sup TM/) is a new photodefinable dielectric material developed by the BF Goodrich Company. A type of cationic photoinitiator, onium salts, is used to initiate the crosslinking reaction of epoxide groups. The reaction mechanism of poly(decylnorbornene-co-epoxidenorbornene) was studied. The structure/properties relationships of the polymer film were investigated. Copolymer composition and process conditions affect the properties of the polymer film. A lower epoxidenorbornene content results in lower dielectric constant, lower residual stress, better adhesion, and good photodefinition, but poor multilayer capability. Lower exposure dose, lower post bake temperature and shorter post bake time improve photodefinition.