Study on Electromigration Effects and IMC Formation on Cu–Sn Films Due to Current Stress and Temperature

Zhao-Ying Wang,Po-Hsun Wang,Terry Yuan-Fang Chen,Ming-Tzer Lin,Nhat Minh Dang

doi:10.3390/app10248893

Zhao-Ying Wang, Po-Hsun Wang + Show 3 more

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https://doi.org/10.3390/app10248893

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Abstract

In this study, the effects of electromigration on a solder/copper substrate due to temperature and current density stress were investigated. The copper–tin (Cu–Sn) film samples were subjected under a fixed current and various heating conditions (130 °C and 180 °C) and current densities (different cross-sectional areas). The micro-structural changes and intermetallic compound (IMC) formation were observed, and failure phenomena (brittle cracks, voids, bumps, etc.) on the structures of samples were discussed. The results showed that the IMC thickness increased as the temperature and current density increased. Moreover, it was found that the higher the temperature and current density was, the greater the defects that were observed. By adjusting the designs of sample structures, the stress from the current density can be decreased, resulting in reduced failure phenomena, such as signal delay, distortion, and short circuiting after long-term use of the material components. A detailed IMC growth mechanism and defect formation were also closely studied and discussed.

Highlights

Electronic packaging, it is the last process to be done, is an indispensable part of the integrated circuit (IC) industry
Analysis of the sample after fabrication; it appears that no intermetallic compound (IMC) were formed during the sample preparation process and that there was a clear interface between Cu and Sn
The results showed that high temperature and high current density affect the degree of IMC formation

Summary

Introduction

Electronic packaging, it is the last process to be done, is an indispensable part of the integrated circuit (IC) industry. It is responsible for connecting the integrated circuit with other electronic components. It prevents the integrated circuit from being damaged by external forces, avoids chemical erosion and the influence of external noise, and increases the cooling path [1,2,3]. Packaging technology can prevent external forces from destroying the integrated circuit, there will always be unavoidable damage under normal use, such as joule heating damage and metal junction diffusion reaction and corrosion [4,5,6,7,8]. If the current passes through the metal conductor for a long time, overheating could occur, causing deformation, damage between the materials due to different expansion coefficients, and faster electromigration because of the thermal energy

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