Evaluation of substrate bias effect on Ta-Ni thin film as Cu diffusion barrier

• Main Author: Jiang, Yueyue
• Other Authors: Chen, Zhong
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/15409
• Institution: Nanyang Technological University

This work examines the thin film properties and diffusion barrier performance of magnetron-sputtered Ta-Ni films. The thin films were deposited on Si substrate with varying RF substrate bias, aiming at depositing highly thermally stable amorphous and conductive diffusion barriers for copper metallization in the integrated circuits. Five different substrate bias powers were utilized and the effects on the film properties were evaluated. Structural analysis indicated that all the as-deposited Ta-Ni films indeed had an amorphous structure and were free from highly resistive intermetallic compounds. Thermal stability test was conducted through thermal vacuum annealing at different elevated temperatures, and it was found that all the films in Si/SiO2/Ta-Ni system were stable up to 700oC; while examining Si/SiO2/Ta-Ni/Cu stack films revealed that only the film with 100W substrate bias applied remained its glassy structure up to 700oC. Four-point probes measurements were also conducted to measure the sheet resistance of the films and a lowest resistivity of 211.48 µΩ.cm could be achieved. Increasing the substrate bias decreased the oxygen incorporation, thus reduced the film resistivity, and enhanced the microstructural and thermal stability of the stacked films, markedly improving the barrier performance.