基于3D封装的纳米孪晶Cu互连机理与可靠性

3D封装互连技术是微电子制造中亟需解决的关键技术。本项目旨在系统研究择优取向纳米孪晶Cu（nt-Cu）作为新型凸点下金属化层（UBM）在3D封装互连中的基础科学问题与潜在的应用价值。阐明基于不同择优取向纳米孪晶Cu/钎料之间的界面反应互连机理与取向效应，揭示纳米孪晶Cu/钎料界面金属间化合物（IMC）生长与晶体取向演变规律；阐明利用电流驱动键合（CBD）新方法在纳米孪晶Cu上单向生长择优取向IMC的机理；阐明nt-Cu/Sn基钎料/nt-Cu与nt-Cu/IMC/nt-Cu微互连焊点在电迁移条件下界面IMC生长的极性效应、微观组织与晶体取向演变规律，揭示纳米孪晶界对界面空位的吸收与抑制Kirkendall孔洞形成的机制；评价纳米孪晶Cu UBM/钎料互连结构的力学性能与失效模式，建立基于择优取向纳米孪晶Cu UBM/钎料互连结构在3D封装中的可靠性理论与评估方法。

Three-dimensional (3D) packaging technology is an issue that needs to be addressed urgently in the development of microelectronics manufacturing technology. The present project aims to research the basic scientific issues and potential application value of preferred oriented nanotwinned Cu (nt-Cu) as a new type of under bump metallization (UBM) in the 3D packaging technology. The project will clarify the interfacial reaction mechanism and the orientation effects of nanotwinned Cu/solder during soldering, reveal the growth and crystal orientation evolution of intermetallic compound (IMC) at the nt-Cu/solder interface; clarify the growth mechanism of preferred orientation IMC on nt-Cu using the new current driven bonding (CDB) method, clarify the polarity effect of interfacial IMC, the evolution rule of microstructure and crystal orientation in Cu/Sn-based solder/nt-Cu and nt-Cu/IMC/nt-Cu micro interconnect undergoing electromigration, reveal the mechanism of interfacial vacancy absorption at twins grain boundaries and the mechanism of twins grain boundaries on inhibiting the formation of Kirkendall voids. The project will characterize the mechanical properties of preferential orientated nt-Cu interconnect and reveal its failure mode and mechanism, establish the reliability theory and evaluation method of cross-scale 3D packaging.