Formation of alternating interfacial layers in Au-12Ge/Ni joints

Shih-kang Lin; Ming-yueh Tsai; Ping-chun Tsai; Bo-hsun Hsu

doi:10.1038/srep04557

Formation of alternating interfacial layers in Au-12Ge/Ni joints

Sci Rep. 2014 Apr 2:4:4557. doi: 10.1038/srep04557.

Authors

Shih-kang Lin¹, Ming-yueh Tsai², Ping-chun Tsai², Bo-hsun Hsu²

Affiliations

¹ 1] Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan [2] Promotion Center for Global Materials Research, National Cheng Kung University, Tainan 70101, Taiwan [3] Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan.
² Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan.

Abstract

Au-Ge alloys are promising materials for high-power and high-frequency packaging, and Ni is frequently used as diffusion barriers. This study investigates interfacial reactions in Au-12Ge/Ni joints at 300 °C and 400 °C. For the reactions at 300 °C, typical interfacial morphology was observed and the diffusion path was (Au) + (Ge)/NiGe/Ni5Ge3/Ni. However, an interesting phenomenon--the formation of (Au,Ni,Ge)/NiGe alternating layers - was observed for the reactions at 400 °C. The diffusion path across the interface was liquid/(Au,Ni,Ge)/NiGe/· · ·/(Au,Ni,Ge)/NiGe/Ni2Ge/Ni. The periodic thermodynamic instability at the NiGe/Ni2Ge interface caused the subsequent nucleation of new (Au,Ni,Ge)/NiGe pairs. The thermodynamic foundation and mechanism of formation of the alternating layers are elaborated in this paper.

Publication types

Research Support, Non-U.S. Gov't