The Self-Annealing Phenomenon in Copper Interconnection

Enhancement of adhesion strength of Cu layer on single and multi-layer dielectric film stack in Cu/low k multi-level interconnects

“…The tensile strength of Cu seed generally decreases with annealing temperature, while its ductility increases [17]. Fig.…”

“…7, it was evident again that stress largely affected the layer properties and adhesion strength of the Cu seed layer [17]. It was noted that the stress of as-deposited single dielectric stack Cu on thin and thick Cu seed was 81.8 and 33.1 MPa at ECP Cu, respectively.…”

Recrystallization of Electrodeposited Copper Thin Films During Annealing

“…It was reported that electrodeposited copper thin films undergo selfannealing-a microstructure evolution process that occurs at room temperature after deposition. [1][2][3][4] During this process the average grain size increases from less than 100 nm to several micrometers in a period of a few hours to a few days after deposition. There was a debate in the literature regarding whether this phenomenon can be described as grain growth, abnormal grain growth, or recrystallization.…”

“…2,3 Self-annealing in copper interconnects was observed to be accompanied by changes in resistivity, texture, roughness, stress, and hardness. [1][2][3][4]10 Among these, resistivity measurements are frequently used to quantify the underlying microstructure evolution because of the relative simplicity. Matthiessen's rule states that the resistivity of a material, q T , can be described by the sum of different contributions, i.e.,…”

High rate of copper electrodeposition from the hexafluorosilicate bath

“…Interest in hexafluorosilicate-based electrolytes for copper electrodeposition was raised again by Hara et al [21,22]. It was shown that electroplated copper layers deposited using these baths have lower electrical resistivity, lower intrinsic stresses and larger grain size, when compared to copper layers deposited from the conventional sulphate electrolyte, even after annealing, which refines grain structure and enhances films conductivity [22].…”