Application for WLP at positive working photosensitive polybenzoxazole

A positive working photosensitive polybenzoxazole (PBO) 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 positive working photosensitive PBO for Wafer Level Packaging (WLP). These cured PBO films have very low water absorption and low dielectric constant in addition to high adhesion to a wide range of substrates including SiO2, etc. Additionally, the patterned profile of the developed and cured film has the desired taper shape, which makes these materials suitable as the interlayer dielectric film for WLP.