Low Temperature Curable Photosensitive Dielectric Materials for WLP Applications

Abstract

A negative working photosensitive polyimide (PSPI) for use as a semiconductor surface coating material has been developed. This material has been widely used as a buffer coating to protect electrical circuitry on IC chips in the semiconductor market. We have now developed a new negative working photosensitive polynorbornene (PSPNB) for Wafer Level Packaging (WLP). These cured PSPNB films have very low water absorption and low dielectric constant in addition to high adhesion to a wide range of substrates including SiO2, etc. The polymer has attractive processing properties, such as a low cure temperature, excellent dielectric properties, and desirable mechanical properties, most notably, low residual stress after cure. A discussion of the polymer properties, processing conditions and the results of the adhesion to a wide range of substrates will be presented.