Abstract
Here, we demonstrate the fabrication of a Cu-graphene heterostructure interconnect by the direct synthesis of graphene on a Cu interconnect with an enhanced performance. Multilayer graphene films were synthesized on Cu interconnect patterns using a liquid benzene or pyridine source at 400 °C by atmospheric pressure chemical vapor deposition (APCVD). The graphene-capped Cu interconnects showed lower resistivity, higher breakdown current density, and improved reliability compared with those of pure Cu interconnects. In addition, an increase in the carrier density of graphene by doping drastically enhanced the reliability of the graphene-capped interconnect with a mean time to failure of >106 s at 100 °C under a continuous DC stress of 3 MA cm−2. Furthermore, the graphene-capped Cu heterostructure exhibited enhanced electrical properties and reliability even if it was a damascene-patterned structure, which indicates compatibility with practical applications such as next-generation interconnect materials in CMOS back-end-of-line (BEOL).
Highlights
As demand for smaller electronic integrated circuits (IC) continues to increase, the width and pitch of interconnects have shrunk; Cu interconnects suffer from size effects such as surface and grain boundary scatterings[1,2,3]
Optical micrograph and scanning electron microscopy (SEM) images show that the Cu interconnect remained physically intact without any change in surface morphology, because the low-temperature process prevented thermal damage to the Cu (Fig. 1a and Supplementary Fig. 2)
Cu grain size in interconnects was expanded by thermal annealing during the graphene synthesis process, which improved the electrical properties of the Cu interconnect (Supplementary Fig. 2)
Summary
As demand for smaller electronic integrated circuits (IC) continues to increase, the width and pitch of interconnects have shrunk; Cu interconnects suffer from size effects such as surface and grain boundary scatterings[1,2,3]. There persist significant challenges for the fabrication of graphene-capped Cu heterostructure interconnects suitable for practical application Aromatic hydrocarbon molecules such as benzene and pyridine are the most favorable carbon source for the direct synthesis of high-quality graphene film at temperatures as low as 300 °C without additional energetic plasma systems[13,14]. The synthesis of high-quality, continuous undoped and Ndoped graphene films was achieved using benzene[13] and pyridine[14] via an oxygen-free APCVD at 300 °C Using this technique, in this study, we developed graphene-capped Cu heterostructure interconnects by the direct synthesis of graphene on a Cu interconnect at 400 °C, which led to improved performance. We confirmed the compatibility of the graphene-capped Cu heterostructure with a damascene-patterned structure for practical applications
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