Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing
The electromigration behavior of microbumps is inevitably altered under bidirectional currents. Herein, based on a designed test system, the effect of current direction and time proportion of forward current is investigated on Cu Pillar/Ni/Sn-1.8 Ag/Cu microbumps. Under thermo-electric stressing, mi...
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| Format: | Article |
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MDPI AG
2023-01-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/3/1134 |
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| author | Zhiwei Fu Jian Chen Pengfei Zhao Xiaotong Guo Qingzhong Xiao Xing Fu Jian Wang Chao Yang Jile Xu Jia-Yue Yang |
| author_facet | Zhiwei Fu Jian Chen Pengfei Zhao Xiaotong Guo Qingzhong Xiao Xing Fu Jian Wang Chao Yang Jile Xu Jia-Yue Yang |
| author_sort | Zhiwei Fu |
| collection | DOAJ |
| description | The electromigration behavior of microbumps is inevitably altered under bidirectional currents. Herein, based on a designed test system, the effect of current direction and time proportion of forward current is investigated on Cu Pillar/Ni/Sn-1.8 Ag/Cu microbumps. Under thermo-electric stressing, microbumps are found to be susceptible to complete alloying to Cu6Sn5 and Cu3Sn. As a Ni layer prevents the contact of the Cu pillar with the solder, Sn atoms mainly react with the Cu pad, and the growth of Cu<sub>3</sub>Sn is concentrated on the Cu pad sides. With direct current densities of 3.5 × 10<sup>4</sup> A/cm<sup>2</sup> at 125 °C, the dissolution of a Ni layer on the cathode leads to a direct contact reaction between the Cu pillar and the solder, and the consumption of the Cu pillar and the Cu pad shows an obvious polarity difference. However, with a bidirectional current, there is a canceling effect of an atomic electromigration flux. With current densities of 2.5 × 10<sup>4</sup> A/cm<sup>2</sup> at 125 °C, as the time proportion of the forward current approaches 50%, a polarity structural evolution will be hard to detect, and the influence of the chemical flux on Cu-Sn compounds will be more obvious. The mechanical properties of Cu/Sn3.0Ag0.5Cu/Cu are analyzed at 125 °C with direct and bidirectional currents of 1.0 × 10<sup>4</sup> A/cm<sup>2</sup>. Compared with high-temperature stressing, the coupled direct currents significantly reduced the mechanical strength of the interconnects, and the Cu-Sn compound layers on the cathode became the vulnerable spot. While under bidirectional currents, as the canceling effect of the electromigration flux intensifies, the interconnect shear strength gradually increases, and the fracture location is no longer concentrated on the cathode sides. |
| first_indexed | 2024-03-11T09:36:18Z |
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| id | doaj.art-3575a528175047b7883e345a9f720cf0 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T09:36:18Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-3575a528175047b7883e345a9f720cf02023-11-16T17:17:36ZengMDPI AGMaterials1996-19442023-01-01163113410.3390/ma16031134Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current StressingZhiwei Fu0Jian Chen1Pengfei Zhao2Xiaotong Guo3Qingzhong Xiao4Xing Fu5Jian Wang6Chao Yang7Jile Xu8Jia-Yue Yang9School of Energy and Power Engineering, Shandong University, Jinan 250100, ChinaScience and Technology on Reliability Physics and Application of Electronic Component Laboratory, China Electronic Product Reliability and Environmental Testing Research Institute, Guangzhou 510610, ChinaSchool of Microelectronics, Xi’an Jiaotong University, Xi’an 710049, ChinaScience and Technology on Reliability Physics and Application of Electronic Component Laboratory, China Electronic Product Reliability and Environmental Testing Research Institute, Guangzhou 510610, ChinaScience and Technology on Reliability Physics and Application of Electronic Component Laboratory, China Electronic Product Reliability and Environmental Testing Research Institute, Guangzhou 510610, ChinaScience and Technology on Reliability Physics and Application of Electronic Component Laboratory, China Electronic Product Reliability and Environmental Testing Research Institute, Guangzhou 510610, ChinaSchool of Energy and Power Engineering, Shandong University, Jinan 250100, ChinaSchool of Energy and Power Engineering, Shandong University, Jinan 250100, ChinaJiaxing Key Laboratory of Flexible Electronics Based Intelligent Sensing and Advanced Manufacturing Technology, Institute of Flexible Electronics Technology of THU, Jiaxing 314000, ChinaSchool of Energy and Power Engineering, Shandong University, Jinan 250100, ChinaThe electromigration behavior of microbumps is inevitably altered under bidirectional currents. Herein, based on a designed test system, the effect of current direction and time proportion of forward current is investigated on Cu Pillar/Ni/Sn-1.8 Ag/Cu microbumps. Under thermo-electric stressing, microbumps are found to be susceptible to complete alloying to Cu6Sn5 and Cu3Sn. As a Ni layer prevents the contact of the Cu pillar with the solder, Sn atoms mainly react with the Cu pad, and the growth of Cu<sub>3</sub>Sn is concentrated on the Cu pad sides. With direct current densities of 3.5 × 10<sup>4</sup> A/cm<sup>2</sup> at 125 °C, the dissolution of a Ni layer on the cathode leads to a direct contact reaction between the Cu pillar and the solder, and the consumption of the Cu pillar and the Cu pad shows an obvious polarity difference. However, with a bidirectional current, there is a canceling effect of an atomic electromigration flux. With current densities of 2.5 × 10<sup>4</sup> A/cm<sup>2</sup> at 125 °C, as the time proportion of the forward current approaches 50%, a polarity structural evolution will be hard to detect, and the influence of the chemical flux on Cu-Sn compounds will be more obvious. The mechanical properties of Cu/Sn3.0Ag0.5Cu/Cu are analyzed at 125 °C with direct and bidirectional currents of 1.0 × 10<sup>4</sup> A/cm<sup>2</sup>. Compared with high-temperature stressing, the coupled direct currents significantly reduced the mechanical strength of the interconnects, and the Cu-Sn compound layers on the cathode became the vulnerable spot. While under bidirectional currents, as the canceling effect of the electromigration flux intensifies, the interconnect shear strength gradually increases, and the fracture location is no longer concentrated on the cathode sides.https://www.mdpi.com/1996-1944/16/3/1134bidirectional currentmicrobumpselectromigrationCu-Sn compound |
| spellingShingle | Zhiwei Fu Jian Chen Pengfei Zhao Xiaotong Guo Qingzhong Xiao Xing Fu Jian Wang Chao Yang Jile Xu Jia-Yue Yang Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing Materials bidirectional current microbumps electromigration Cu-Sn compound |
| title | Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing |
| title_full | Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing |
| title_fullStr | Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing |
| title_full_unstemmed | Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing |
| title_short | Interfacial Reaction and Electromigration Failure of Cu Pillar/Ni/Sn-Ag/Cu Microbumps under Bidirectional Current Stressing |
| title_sort | interfacial reaction and electromigration failure of cu pillar ni sn ag cu microbumps under bidirectional current stressing |
| topic | bidirectional current microbumps electromigration Cu-Sn compound |
| url | https://www.mdpi.com/1996-1944/16/3/1134 |
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