Abstract Silver sintering is a promising die attach technology to ensure high thermal reliability. The long-term reliability of SiC device sintered by nano-Ag paste has been evaluated by the high temperature storage (HTS) process at 350 °C in air and vacuum, respectively. Although the SiC chip and direct bonding copper (DBC) substrate could be bonded firmly by the nano-Ag paste after sintering at low temperature, the microstructure and shear strength of sintered die attachment experienced the huge evolution during HTS process. The bondline of die attachment became compact, and some pores grow up and pore distribution became nonuniform after HTS in air. While the densification of bondline was significantly delayed because residual organics inhibited the growth and migration of pores during HTS in vacuum. The shear strength of die attachment first increased then decreased slowly with the increasing of storage time. The fracture surface showed that the Ni(P) layer was oxidized, and the formed NiO layer provided the failure location. The results indicated that the electroless nickel/immersion gold (ENIG) surface of DBC substrate was not the ideal metallization when the sintered die attachment applied at the long-term high temperature.

中文翻译：

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高温应用中用于 SiC 功率器件的银烧结芯片的微观结构和机械演变

摘要 银烧结是一种很有前途的芯片贴装技术，可确保高热可靠性。纳米银浆烧结的 SiC 器件的长期可靠性已通过高温储存 (HTS) 工艺在 350 °C 的空气和真空中分别进行评估。尽管在低温烧结后，碳化硅芯片和直接键合铜（DBC）衬底可以通过纳米银浆牢固地键合，但烧结芯片的微观结构和剪切强度在高温超导工艺过程中经历了巨大的变化。在空气中高温超导后，晶粒附着的粘合层变得致密，部分气孔长大，气孔分布变得不均匀。而由于残余有机物抑制了真空高温超导过程中孔隙的生长和迁移，胶层的致密化显着延迟。模具附着体的剪切强度随着存放时间的增加先增加后缓慢下降。断口显示Ni(P)层被氧化，形成的NiO层提供了失效位置。结果表明，当烧结芯片附着在长期高温下应用时，DBC衬底的化学镀镍/浸金（ENIG）表面不是理想的金属化。