[16a-B10-1~13] 13.4 Si wafer processing /Si based thin film /MEMS/Integration technology

△ [16a-B10-4] Fabrication of Low Resistivity Metal/Ge Contact with Amorphous Zr-Ge-N Interlayer

〇Hayato Okamoto¹, Keisuke Yamamoto², Dong Wang¹, Hiroshi Nakashima² (1.IGSES, Kyushu Univ., 2.KASTEC, Kyushu Univ.)

Keywords:germanium, contact resistance, metal/semiconductor contacts

A metal/Ge contact with ultralow contact resistance is necessary to achieve high-performance Ge n-MOS devices. However, Fermi-level pinning (FLP) phenomenon which pins metal Fermi level near the valence band edge of Ge bandgap, prevent to achieve low contact resistance. We have already reported that sputter deposited ZrN/Ge structure has nitrogen contained amorphous interlayer (a-IL·N) and it alleviate FLP from valence band edge to conduction band side. As a result, ZrN/Ge structure has extremely low electron barrier height. However, its specific contact resistivity was still as high as 6.3×10^-4 Ωcm². In this study, we tried to form metal/a-IL·N/Ge contact with ultralow contact resistivity by replacement of ZrN to lower work function metal. As a result, Ag/a-IL·N/n⁺-Ge structure showed low specific contact resistivity of 7.15×10^-7 Ω·cm² with Ge surface donor concentration of N_D=3.9×10¹⁹ cm^-3.