Copper direct bonding: An innovative 3D interconnect

Abstract

3D technology will be the next step for the development of microelectronic devices. Vertical interconnection is one of the challenging issues. Cu/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> patterned surface might be one of the possible techniques to address it. In this work, direct patterned Cu/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> surfaces bonding at room temperature, atmospheric pressure and ambient air is demonstrated. High alignment and bonding quality is achieved for both Wafer to Wafer (WtW) and Die to Wafer (DtW) bonding. Electrical characterizations of Cu/Cu contacts are presented for multiple contact areas and post bonding annealing temperature. The specific contact resistance is lowered down to ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> =47 mΩ.μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for 3×3μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Cu/Cu contacts on Kelvin structures.