Effects of two-step plasma treatment on Cu and SiO<sub>2</sub> surfaces for 3D bonding applications
Han Kyeol Seo, Sarah Eunkyung Kim, Gahui Kim, Hae Sung Park, Young-Bae Park
Abstract
Cu-to-Cu bonding is necessary for high density, fine-pitch interconnect and high bandwidth in 3D stacking technology. Although various Cu-to-Cu bonding studies have been reported so far, few challenges still are remaining such as atmospheric oxidation of Cu, high bonding temperature and pressure not suitable for mass production. In this study, we evaluated low temperature Cu-to-Cu bonding with two step plasma treatment using Ar and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The effects of Ar and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma treatment on Cu and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> surfaces were investigated especially for Cu/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> hybrid bonding applications. The two-step plasma treatment was produced copper nitride passivation layer to prevent further oxidation of copper in the air. The two-step plasma treated SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> surface showed some nitrogen bonding with Si, but no effects on electrical property.