We explore a methodology for patterned copper nanoparticle paste for 3D interconnect applications in wafer to wafer (W2W) bonding. A novel fine pitch thermal compression bonding process (sintering) with coated copper nanoparticle paste was developed. Most of the particle size is between 10-30 nm. Lithographically defined stencil printing using photoresist and lift-off was used to apply and pattern the paste. Variations in sintering process parameters, such as: pressure, geometry and ambient atmosphere, were studied. Compared to Sn-Ag-Cu (SAC) microsolder bumps, we achieved better interconnect resistivity after sintering at 260 °C for 10 min, in a 700 mBar hydrogen forming gas (H2/N2) environment. The electrical resistivity was 7.84 ± 1.45 μΩ·cm, which is about 4.6 times that of bulk copper. In addition, metallic nanoparticle interconnect porosity can influence the electrical properties of the interconnect. Consequently, we investigated the porosity effect on conductivity using finite element simulation. A linear relationship between the equivalent conductivity and particle overlapping ratio was found.
Original languageEnglish
Title of host publicationProceedings of the 17th International Conference on Electronic Packaging Technology (ICEPT)
EditorsKeyun Bi, Sheng Liu, Shengjun Zhou
ISBN (Print)978-1-5090-1396-8
Publication statusPublished - 2016
Event17th International Conference on Electronic Packaging Technology - Wuhan, China
Duration: 16 Aug 201619 Aug 2016
Conference number: 17


Conference17th International Conference on Electronic Packaging Technology
Abbreviated titleICEPT

    Research areas

  • Interconnect, 3D packaging, opper nanoparticle paste, low-temperature sintering

ID: 9913344