Fabrication and shear strength analysis of Sn-3.5Ag/Cu-filled TSV for 3D microelectronic packaging

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• 作者：Ashutosh Sharma ; Do-Hyun Jung ; Myong-Hoon Roh ; Jae Pil Jung
• 关键词：through ; Si ; via (TSV) ; electroplating ; electrolyte ; microstructure ; solder ; reflow
• 刊名：Electronic Materials Letters
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：12
• 期：6
• 页码：856-863
• 全文大小：2,049 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Condensed Matter Physics
  Electronics, Microelectronics and Instrumentation
  Optical and Electronic Materials
  Thermodynamics
  Characterization and Evaluation of Materials
  
• 出版者：The Korean Institute of Metals and Materials, co-published with Springer Netherlands
• ISSN：2093-6788
• 卷排序：12

文摘

In this study, lead free Sn-3.5Ag solder bumps have been deposited on Cu-filled through-silicon via (TSV) by electroplating method. The solder bumps are plated using an acidic solution composed of SnSO₄, H₂SO₄, Ag₂SO₄, thiourea and an additive. The current density is varied from −30 to −60 mA/cm2 to obtain the eutectic Sn-3.5Ag solder. The copper is electroplated in TSV using an acidic solution of CuSO₄·5H₂O, H₂SO₄, HCl, and an inhibitor. The bottom-up Cu-filling in TSV is achieved by a 3-step pulse periodic reverse (PPR) electroplating. It has been observed that the eutectic Sn-3.5Ag solder is achieved at a current density of −55 mA/cm2. The solder bumps are further reflowed onto TSV at 260 °C for 20 seconds, and shear strength of the formed Sn-3.5Ag/Cu-filled TSV joint is investigated. The results indicate the formation of Cu₆Sn₅ and Ag₃Sn intermetallic compounds (IMCs) at the joint interface. It is found that with an increase of shear speed from 0.5-10 mm/s, the shear stress initially increases to a maximum, and then decreases beyond shear speed of 10 mm/s through 500 mm/s. It is shown that the ductile fracture mode gradually decreases beyond shear speed of 10 mm/s and disappears completely at 500 mm/s.