Higher reliability for low-temperature curable positive-tone photosensitive dielectric materials

Abstract

Fan-Out Wafer Level Packages (FOWLPs) and Fan-Out Panel Level Packages (FOPLPs) have been proposed for promising candidates of the advanced packages for multifunctional LSI with many I/O (input/output). FOPLP is expected to reduce the cost of FOWLP by improving the productivity per substrate. Dielectric materials for redistribution layers (RDLs) are one of the most important materials for FOPLPs. We have developed the novel low-temperature curable positive-tone photosensitive dielectric materials for high reliability packages and insulating layers for FOPLPs. Dielectric materials mainly focus on two factors for high package reliability. One is insulating layer with high elongation and the suppression of growing a copper oxide layer from copper RDLs during reliability tests. Cured films with compositions based on the above polymer with conventional cross-linkers showed the high elongation property up to 70%. Moreover, the appropriate additive has made the copper oxide layer suppressed to grow during reliability tests. Furthermore, we have also found that strong adhesion has been achieved between dielectric layers and RDLs with fewer voids. This dielectric material is expected to be the key material in contribution efforts to enhance the semiconductor device packaging reliability for FOPLPs.