Abstract
Thermal inkjet technology is in widespread use for color printers. In the roof-shooter thermal inkjet printhead, tantalum is often used as the diffusion barrier between the gold and the conduction layers, Al, Cu, and Al-Cu. This study investigated the contact stabilities of Al/Ta, Cu/Ta, and Al-Cu/Ta systems using the reaction couple technique. The couples were annealed in a furnace at 600°C, 750°C, 900°C, 1000°C, and 1200°C for various lengths of time. One reaction layer, the Al 3 Ta phase, was formed at the interface in the Al/Ta and Al-Cu/Ta couples heat treated at 750°C, 900°C, and 1000°C. No Cu is observed in the Al 3 Ta phase even in the Al-Cu/Ta couples; however, the reaction couples with Al-Cu have slower reaction rates. For the Al/Ta reaction couples annealed at 600°C and Cu/Ta couples annealed at 750°C, 900°C, 1000°C, and 1200°C, no noticeable interfacial reaction was observed. It was concluded that the contacts were very stable and Ta was a very good barrier layer. In addition, phase equilibria studies of the Al-Ta system were carried out. The experimental results indicate that the Al 2 Ta phase was not stable at 850°C and higher. A revised Al-Ta phase diagram was proposed in this study.