次世代三次元積層半導体用 Ag/Sn系多層薄膜電極間接合に関する研究

Abstract

Through-silicon via (TSV) technology for 3D stacking is attracting much attention as a means of alleviating the miniaturization limits on advanced semiconductor devices. Despite a great deal of research, low load (<1 MPa), low temperature (<473 K) and short time (<300 s) solid phase bonding with high heat resistance (>623 K) to prevent the damage of weak low-k dielectric material etc. has not been realized. In this work, we examine a new Ag-Sn thin film bonding system to replace Cu-Cu direct bonding. It is found that Ag/Sn/nano Ag-nano Ag/Sn/Ag thin film bonding systems (especially when the film thickness of the surface Ag is controlled to around 10nm) is a promising approach because 1) it enables low load (<0.4 MPa), low temperature (<453 K) and short time (<300 s) bonding, and 2) the bonded interface has a high heat resistance (>673 K) and joint strength (>29 MPa). It is found that it may be possible to realize an optimal solid phase bonding system for wafer-level 3D-stacking for 3D-IC which can satisfy a hierarchical temperature based bonding method that include TSV formation.