| Title |
Thermal Stability of Ta Diffusion Barriers Deposited by Applying Substrate Bias Voltage |
| Authors |
임재원(Im Jae Won); 배준우(Bae Jun U); (Minoru Isshiki) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Tantalum; Diffusion barrier; Ion beam deposition; Resistivity; Substrate bias voltage; Thermal stability |
| Abstract |
The interfacial reactions of the Cu(100 nm)/Ta(50 nm)/Si structures and their relationship with the microstructure of Ta diffusion barriers are investigated. The Ta films were deposited on Si (100) substrates at various bias voltages ranging from 0 to -200 V. The Ta diffusion barrier which was deposited at the substrate bias voltages of -50 V and -125 V prevented Cu-Si interaction up to 600℃ in flowing purified H₂ for 60 min, whereas the Ta layer with a columnar structure which was deposited at zero bias voltage degraded at 400℃. It was found that a slight resistivity increase of the Cu/Ta(-50 V or -125 V)/Si structures at 650℃ seemed to be due to a Cu agglomeration. To confirm the thermal stability of the Ta diffusion barrier deposited at the substrate bias voltage, a SiO₂ capping layer was used as a suppressor and was deposited on the Cu/Ta(-125 V)/Si structure. As a result, the Cu/Ta(-125 V)/Si structures were stable up to 650℃ without the Cu-Si interaction. Two different reactions of the Cu/Ta(0 V)/Si and the Cu/Ta(-50 V or -125 V)/Si structures concerning the thermal stability were discussed on the basis of the experimental results. |