| Summary: | 碩士 === 國立虎尾科技大學 === 材料科學與工程系材料科學與綠色能源工程碩士班 === 107 === Use of self-forming Cu alloy thin film is essential for application in state-of-the-art Cu interconnects due to the high aspect ratio of the trenches/vias. The self-forming Cu alloy thin film can be a barrier to prevent Cu diffusion after annealing the film at an elevated temperature by triggering the alloy element diffusion out of the Cu matrix. Thus, the Cu alloy film can potentially replace the conventional Ta/TaN as the barrier and act as the seed layer for Cu electrochemical deposition. However, Cu alloy films were normally deposited by sputter. The sputter deposition can make the film with a low step coverage. In this study, Cu(Mn) alloy thin film was deposited by electrochemical atomic layer deposition, and properties of the Cu(Mn) alloy films were investigated.
The Cu(Mn) films were deposited by alternating underpotential-deposition (UPD) of Mn and surface-limited redox replacement (SLRR) of Cu for 50 cycles. Through these sequences, concentration of the resultant Cu(Mn) film can be adjusted by controlling the replacing time of SLRR-Cu. After that, the Cu(Mn) alloy films were subjected to evaluate the thermal stability. The experimental results show that UPD-Mn deposited at -800 mV for 60 s followed by SLRR-Cu for 60 s can yield a Cu(Mn) film with a resistivity of 20 μΩ-cm. Further, this study shows that the Mn concentration can be successfully controlled by controlling the time of SLRR-Cu. The low-resistivity Cu(Mn) film has a Mn concentration of 1.72 at.%, and is thermally stable up to 600 °C. The proposed method can be a renewed interest in the microelectronics for Cu interconnections.
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