Reliability of WLP Structures Fabricated with ALX Dielectric Polymer

摘要

For wafer level packaging (WLP) applications, BCB, polyimides, epoxies, and PBO are the predominant spin-on dielectricrnmaterials used for repassivation, redistribution, and stress buffering. Each of these materials has their respective strengths andrnweaknesses in process and in reliability. Asahi Glass Co., LTD has developed a new spin-on dielectric polymer (ALX) designedrnfor WLP applications that provides a unique set of material properties coupled with a low curing temperature. We havernpreviously presented process evaluation and optimization data on ALX polymer material, which showed an application processrnsimilar to BCB with wide process latitude. In this paper we present the results of a study done to evaluate the performance ofrnALX polymers in WLP test structures fabricated at RTI International. Typical solder bumped repassivation and bump-onpolymerrntest structures have been fabricated using ALX and BCB and evaluated through bump shear tests. We have alsornevaluated the adhesion of ALX to typical materials encountered in WLP structures through shear testing free-standing polymerrnstructures.