Abstract
This work presents the synthesis of tin-doped copper nanowires by introducing Sn not only as a catalyst to enhance the reduction of Cu but also as a dopant to grow the tin-doped copper NWs at low temperature (≦ 400 °C). It is believed that tin-doped copper NWs are good candidates for future CMOS interconnect applications because of their good electrical properties. In addition, this work is also focused on the optimization of the thickness of Sn, pretreatment of substrates, temperature, pressure, and the ratio of precursor compositions to obtain the high-density nanowires. The tin-doped copper nanowires (25 μm in length and 50–200 nm in diameter) have been successfully synthesized by chemical vapor deposition (CVD) using the Cu and SnCl2 powders as precursors. The morphology and crystalline structure of the tin-doped copper nanowires were characterized by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM), respectively. Additionally, the mechanism of Cu(Sn) nanowires formation is proposed to be vapor–liquid-solid (VLS) reaction growth. Finally, Cu(Sn) nanowires (NWs) were also synthesized in the via hole to confirm the ability for interconnect application. In electrical properties part, the tin-doped copper NWs exhibit low resistivity (3 μΩ-cm), which is the lowest value reported so far, and maximum current density (3.16×107 A/cm2). It indicates that tin-doped copper NWs exhibit great potential to be future interconnect materials.