Bonding Strength of Cu Sinter Die-Bonding Paste on Ni, Cu, Ag, and Au Surfaces under Pressureless Bonding Process

Dai Ishikawa; Bao Ngoc An; Matthias Mail; Helge Wurst; Benjamin Leyrer; Thomas Blank; Marc Weber; Suguru Ueda; Hideo Nakako; Yuki Kawana

doi:10.5104/jiepeng.13.E19-017-1

Technical Papers

Bonding Strength of Cu Sinter Die-Bonding Paste on Ni, Cu, Ag, and Au Surfaces under Pressureless Bonding Process

Dai Ishikawa, Bao Ngoc An, Matthias Mail, Helge Wurst, Benjamin Leyrer, Thomas Blank, Marc Weber, Suguru Ueda, Hideo Nakako, Yuki Kawana

Author information

Dai Ishikawa
Hitachi Chemical Co., Ltd.
Bao Ngoc An
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology
Matthias Mail
Institute of Nanotechnology, Karlsruhe Institute of Technology
Helge Wurst
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology
Benjamin Leyrer
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology
Thomas Blank
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology
Marc Weber
Institute for Data Processing and Electronics, Karlsruhe Institute of Technology
Suguru Ueda
Hitachi Chemical Co., Ltd.
Hideo Nakako
Hitachi Chemical Co., Ltd.
Yuki Kawana
Hitachi Chemical Co., Ltd.

Keywords: Copper Sinter Die-bonding Paste, Pressureless Sintering, Shear Strength, Diffusion Coefficient, Interdiffusion, Kirkendall Void, Molecular Dynamics Simulation

JOURNAL FREE ACCESS

2020 Volume 13 Pages E19-017-1-E19-017-11

DOI https://doi.org/10.5104/jiepeng.13.E19-017-1

Details

Abstract

Herein we report on a copper (Cu) sinter die bonding paste that sinters under pressureless bonding conditions for power devices operating at high temperatures. The shear strengths of pressureless sintered Cu on four different metallization layers (Ni, Cu, Ag, and Au) were studied by experiment. The sintering behavior of Cu nanoparticles and diffusion coefficients at interfaces between a bulk Cu layer and the metallization layers was also evaluated by molecular dynamics (MD) simulation. After aging (573 K, 8 h), the shear strength of the Cu sintered to the Ni and Cu layers increased, whereas that of Cu sintered to the Ag and Au layers decreased. The interdiffusion at the interfaces between the sintered Cu layer and the Ag or Au layer increased the interfacial porosity of sintered Cu, which decreased the shear strengths in the sintered Cu/Ag and Cu/Au systems. In contrast, the interfacial porosity between the sintered Cu and the Ni or Cu layer hardly changed after aging. MD simulations revealed that Kirkendall voids were promoted by higher interdiffusion coefficients and a higher ratio of intrinsic diffusion coefficients between a bulk Cu layer and an Ag or Au layer. This consequently increased the porosity of Cu sintered near the interfaces.

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