| 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. |
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| Key Words |
| Tantalum, Diffusion barrier, Ion beam deposition, Resistivity, Substrate bias voltage, Thermal stability |
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