Controlling Underfill on Die in Multichip Heterogenous Integration With Large Die Height Delta

Intel Ponte Vecchio GPU is one of the most complex systems on chip products ever built. Its Co-embedded multidie interconnect bridge (EMIB) architecture combines EMIB and Foveros technologies and employs dies from different foundries. These dies have different die heights, and the large die height delta results in a unique failure mode, underfill on die (UOD). This article discusses the fundamental mechanism and potential solution paths, including trenches, surface modifications, and a barrier structure. Lab-level proof-of-concepts (POCs) were carried out to understand the effectiveness and implementation challenges of the proposed solutions. It was found that the trench structure provided sufficient process capability at reasonable cost and minimal interaction risk and therefore was selected as the path for high-volume manufacturing (HVM). The key process modulators in the high-volume implementation of trench are also discussed.