The property of Ta as a diffusion barrier is studied for Al/Ta/Si structure. Interfacial reactions of Al(180 nm)/Ta(130 nm)/Si and Al(180 nm)/Ta(24 nm)/Si, in the temperature range 450∼600°C for 30 min, have been investigated. In Al/ Ta(130 nm)/Si system, which is Ta-excess case, Al3Ta is formed at 500°C. At 575°C, TaSi2 is formed at the interface of Ta Si. At 600°C, after Al3Ta decomposes at the interface of Al3Ta TaSi2, free Ta is bonded to TaSi2 with the supply of Si from Si substrate and free Al diffuses through TaSi2, resulting in Al spiking. In Al/Ta(24 nm)/Si system, which is Al-excess case, Al3Ta is formed at 500°C. At the same temperature of 500°C, after Al3Ta decomposes at the interface of Al3Ta/Si, free Ta reacts with Si to form TaSi2 and free Al diffuses to Si substrate, resulting in Al spiking. The results of interfacial reactions can be understood from the calculated Al-Si-Ta ternary phase diagram. It can be concluded that the reaction at Al/Ta should be suppressed to improve the performance of Ta diffusion barrier in Al/Si system.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry