J. Iijima

Growth kinetics and thermal stability of a self-formed barrier layer at Cu-Mn∕SiO2 interface

A thin diffusion barrier was self-formed by annealing at an interface between a Cu-Mn alloy film and a SiO2 substrate. The growth of the barrier layer followed a logarithmic rate law, which represents field-enhanced growth mechanism in the early stage and self-limiting growth behavior in the late stage. The barrier layer was stable at 450 °C for 100 h and at 600 °C for 10 h. The interface diffusivity was estimated from the morphology change of the barrier layer at 600 °C and was found to be smaller than the grain-boundary diffusivity of bulk Cu.

Growth behavior of self-formed barrier at Cu–Mn∕SiO2 interface at 250–450°C

A diffusion barrier layer was self-formed at the interface between Cu–Mn alloy and tetraethylorthosilicate oxide layers at 250–450°C. No interdiffusion occurred across the self-formed barrier layer during annealing at these temperatures up to 100h. The growth of the barrier layer obeyed a logarithmic law and depended on manganese concentration. The barrier thickness could be controlled in the range of 2–8nm.

Resistivity reduction by external oxidation of Cu–Mn alloy films for semiconductor interconnect application

A self-forming barrier process using Cu–Mn alloy has been reported to exhibit excellent reliability for interconnect lines in advanced semiconductor devices. However, Mn increases resistivity. In this work, the authors investigated optimum annealing conditions to remove Mn from the Cu–Mn alloy by forming an external Mn oxide and to reduce resistivity to a level of pure Cu. The results were interpreted by an external oxidation mechanism of Mn atoms.

Cu Alloy Metallization for Self-Forming Barrier Process

A novel Cu-Mn alloy has been developed to self-form a diffusion barrier layer at metal/dielectric interface without depositing a conventional metal barrier layer. The integration results are reviewed first to show its excellent reliability and electrical characteristics. Selection criteria of the alloying element are delineated. The reason why Mn is better than other elements is explained in terms of thermodynamic activity. The impacts of the self-forming barrier process on the BEOL process are discussed

Growth Behavior of Self-Formed Barrier Using Cu-Mn Alloys at 350 to 600oC

Cu-Mn alloys were deposited on plasma TEOS dielectric layer. A diffusion barrier layer was self-formed at the interface during annealing at elevated temperatures. The growth behavior followed a logarithmic rate law at 350 and 450 degC. No interdiffusion occurred between the alloy film and TEOS after annealing at these temperatures for 100 h. At 600 degC, grain-boundary grooving of the alloy film occurred on the barrier interface side. Estimated diffusivity at the alloy/barrier interface was of the same order as grain-boundary diffusivity of Cu