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<p>Full intermetallic compound (IMC) interconnects have emerged as a promising die-attach solution for third-generation semiconductor power devices that operate at higher temperatures. This study aims to fabricate Cu/(Cu,Ni)<sub>6</sub>Sn<sub>5</sub>/Cu full IMC interconnects by the current driven bonding (CDB) method with Sn-5Cu-5Ni composite solder to achieve higher reliability. The use of Sn-5Cu-5Ni composite solder reduced the processing time by approximately 1/3 to only 10&#xa0;min, and significantly refined (Cu,Ni)<sub>6</sub>Sn<sub>5</sub> grains from 39.59 to 2.36&#xa0;μm, compared to common pure Sn solder. Even after current stressing (150&#xa0;°C, 1.0 × 10<sup>4</sup>&#xa0;A/cm<sup>2</sup>) for 500&#xa0;h, the interfacial (Cu,Ni)<sub>3</sub>Sn in full (Cu,Ni)<sub>6</sub>Sn<sub>5</sub> IMC interconnect increased by only 0.34&#xa0;µm in thickness, in comparison to 2.92&#xa0;μm for Cu<sub>3</sub>Sn in full Cu<sub>6</sub>Sn<sub>5</sub> IMC interconnect. First-principles calculations indicated that doping Ni increased the diffusion activation energy (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10854_2025_14635_Article_IEq1.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="20" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{Q}}_{\text{a}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mtext>Q</mtext> <mtext>a</mtext> </msub> </math></EquationSource> </InlineEquation>) for Cu atoms diffusing in Cu<sub>6</sub>Sn<sub>5</sub> and Cu<sub>3</sub>Sn, from 1.60 and 1.56&#xa0;eV/atom to 2.08 and 1.68&#xa0;eV/atom, respectively, thereby inhibiting the growth of interfacial (Cu,Ni)<sub>3</sub>Sn. The average shear strength of full (Cu,Ni)<sub>6</sub>Sn<sub>5</sub> IMC interconnects in as-fabricated state was 64.1&#xa0;MPa and remained to be 62.8&#xa0;MPa even after current stressing for 500&#xa0;h, showing an excellent EM resistance. These findings suggest that the CDB method utilizing the composite solder is expected to realize full IMC interconnects with high strength and high EM reliability.</p>

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Microstructure and reliability of full (Cu,Ni)6Sn5 IMC interconnects fabricated by current driven bonding method with Sn-5Cu-5Ni composite solder

  • 期刊论文

  • 发表日期：

    2025年4月1日

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  • P. Liu,
  • J. Ren,
  • M. L. Huang

摘要

Full intermetallic compound (IMC) interconnects have emerged as a promising die-attach solution for third-generation semiconductor power devices that operate at higher temperatures. This study aims to fabricate Cu/(Cu,Ni)6Sn5/Cu full IMC interconnects by the current driven bonding (CDB) method with Sn-5Cu-5Ni composite solder to achieve higher reliability. The use of Sn-5Cu-5Ni composite solder reduced the processing time by approximately 1/3 to only 10 min, and significantly refined (Cu,Ni)6Sn5 grains from 39.59 to 2.36 μm, compared to common pure Sn solder. Even after current stressing (150 °C, 1.0 × 104 A/cm2) for 500 h, the interfacial (Cu,Ni)3Sn in full (Cu,Ni)6Sn5 IMC interconnect increased by only 0.34 µm in thickness, in comparison to 2.92 μm for Cu3Sn in full Cu6Sn5 IMC interconnect. First-principles calculations indicated that doping Ni increased the diffusion activation energy ( \({\text{Q}}_{\text{a}}\) Q a ) for Cu atoms diffusing in Cu6Sn5 and Cu3Sn, from 1.60 and 1.56 eV/atom to 2.08 and 1.68 eV/atom, respectively, thereby inhibiting the growth of interfacial (Cu,Ni)3Sn. The average shear strength of full (Cu,Ni)6Sn5 IMC interconnects in as-fabricated state was 64.1 MPa and remained to be 62.8 MPa even after current stressing for 500 h, showing an excellent EM resistance. These findings suggest that the CDB method utilizing the composite solder is expected to realize full IMC interconnects with high strength and high EM reliability.