Room temperature bonding of SiO 2 and SiO 2 by surface activated bonding method using Si ultrathin films

• Published in: Japanese Journal of Applied Physics Vol. 55; no. 2; p. 26503
• Main Authors: Utsumi, Jun, Ide, Kensuke, Ichiyanagi, Yuko
• Format: Journal Article
• Language: English
• Published: 01.02.2016
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.55.026503

Abstract The bonding of metal electrodes and insulator hybrid interfaces is one of the key techniques in three-dimensional integration technology. Metal materials such as Cu or Al are easily directly bonded by surface activated bonding at room temperature, but insulator materials such as SiO 2 or SiN are not. Using only Si ultrathin films, we propose a new bonding technique for SiO 2 /SiO 2 bonding at room temperature. Two SiO 2 surfaces, on which Si thin films were deposited, were contacted in vacuum. We confirmed that the thickness of the layer was about 7 nm by transmission electron microscopy observation and that the layer was non crystalline by electron energy loss spectroscopy analysis. No metal material was found in the bonding interface by energy-dispersive X-ray spectroscopy analysis. The surface energy was about 1 J/m 2 , and the bonding strength was more than 25 MPa. This bonding technique was successfully realized to enable SiO 2 /SiO 2 bonding without a metal adhesion layer.