Room-temperature intermixing for adhesion enhancement of Cu/SiO₂interface by adopting SiO₂surface dope and noble metal catalyzation

Abstract

We demonstrated a novel and simple approach to obtain a reliable Cu/SiO 2 stack. The key is the combination of SiO 2 surface doping with Zn and intermixing acceleration by a noble metal catalyst. Zn was incorporated into the SiO 2 surface by heat treatment of ZnO/SiO 2 stacks. The intermixing layer was formed even when Cu films were deposited at room temperature, and this layer dramatically improved the adhesion between Cu and SiO 2 .

Formation of zinc oxide thin film using supercritical fluids and its application in fabricating a reliable Cu/glass stack

“…In these spectra, Cu, Pt, Si, and their oxides were clearly visible, indicating that an intermixing layer was formed at the Cu/glass interface. Similar formation of intermixing layer was also observed in our previous studies [5,20]. In our previous study, no Zn was detected by XPS in the intermixing layer formed in the Cu/Pt/Zn-doped glass stacks, although a small amount of Zn was obviously observed in Cu films and the intermixing layer by using transmission electron microscopy [21].…”

“…Finally, Cu films were sputtered to a thickness of 50 nm with no intentional substrate heating or cooling. These deposition conditions are our standard for obtaining high adhesion [5]. The adhesion strength was evaluated with a micro-scratch tester (Rhesca CSR-2000) following Japanese Industrial Standard R3255 specifications [16], where the load applied to the horizontally vibrating stylus was increased continuously with the traveling displacement of the stylus.…”

“…6 shows the XPS depth spectra of Cu 2p 1/2 , Cu 3p 1/2 , Zn 2p 1/2 , O 1s, Pt 4f 5/2 , and Pt 4f 7/2 core levels obtained from the Cu/Pt/Zn-doped glass stack fabricated using the SFCD-ZnO films. The analyses were performed from the Cu film to the glass Cu/glass [20] Cu/Pt/Zn-doped glass (using white SFCD-ZnO) Cu/Pt/Zn-doped glass (using brown SFCD-ZnO) 5 8 7 2 1 substrate across the interface. The order of the spectra is the same as that in Fig.…”

“…The key in this process is the combination of Zn doping and noble metal catalyzation, which accelerates atomic intermixing at the Cu/glass interface. For obtaining the Zn-doped glass surface, annealing of the ZnO/glass stack during or after ZnO deposition was effective treatment [5].…”

“…This layer was formed by doping the glass surface with Zn followed by noble metal catalyzation [5], and this intermixing layer significantly improved the adhesion at the Cu/glass interface. The fabrication process is shown in Fig.…”