Submicron Cu/Sn Bonding Technology With Transient Ni Diffusion Buffer Layer for 3DIC Application

Abstract

A submicron Cu/Sn bonding with transient Ni buffer layer at 225°C is demonstrated to overcome current 5-µm Cu/Sn physical limitation. The 10-nm Ni layer suppresses immense Cu/Sn interdiffusion during heating step prior to major bonding process. When the temperature is close to the Sn melting point, the Ni layer dissolves and molten Sn gives successful submicrometer Cu/Sn bonding. The excellent mechanical strength and electrical performance of this scheme show the great potential for future and highly dense 3D interconnects.

High-Temperature Mechanical Integrity of Cu-Sn SLID Wafer-Level Bonds

“…[11,[13][14][15][16][17][18] Although these tests were performed to prove the technology for high-temperature applications, the shear strength of the tested samples was all carried out at room temperature. Mechanical integrity at temperature surpassing the melting temperature of Sn has long been predicted, but experimental verification is scarce.…”