Novel Bonding Process Using Ultra-thin Mn for Highly Robust and Reliable Cu/SiO Hybrid Bonding

We propose a new Cu/SiO hybrid bonding process using ultrathin Mn film at the bonding interface. In this process, bonding stability is improved because the bonding interface consists of only Mn. In addition, Mn on SiO forms a MnSiO, which is known as a diffusion barrier for Cu during thermal processing, resulting in improved reliability of interconnects in areas of misalignment. To demonstrate the feasibility of this process, we evaluated the bonding strength of Mn/Mn interface and electrical properties of ultrathin Mn film on SiO layer. Good bonding strength was obtained at heating temperatures of 350°C or more. Moreover, it was confirmed that the resistivity of ultrathin Mn film on SiO layer was increased by heat treatment.