| Summary: | 博士 === 國立交通大學 === 材料科學與工程系 === 91 === Electroplating (ECP) has been the leading method for Damascene Cu deposition in multilevel interconnection due to its low cost, high throughput and superior gap-filling capability. To achieve defect-free filling in sub-0.2 m trenches/vias, various plating baths and process conditions are investigated in the literatures. Precisely control of Cu ECP is both essential and difficult. Defect-free filling is usually obtained at a rigidly process window. Furthermore the plating chemistries are too complicated to predict and control because they are usually proprietary and they may cleave, decay and co-react during Cu ECP. Further studies are needed to realize the electrochemical behaviors of Cu ECP. In this thesis, polarization, organic additives, post-ECP annealing and pulse current of Cu ECP are studied to optimize the film properties and gap-filling capabilities.
For next technology node, super-low-k dielectrics (k<3) will be adopted in the Cu Damascene process to reduce RC delay of interconnect. However, integrating new materials would face with many process challenges. In particular, low-k dielectrics with porous structure would be mechanically weaker than silicon dioxide. Typically chemical mechanical polishing (CMP) processes will cause sever damage on low-k films. Cu electropolishing (EP) is recently explored as a replacement of Cu-CMP. An applied electric field is substituted for the mechanical force component in CMP to remove excess Cu layers. The stress-free characteristic of Cu EP can handle low-k dielectrics. Furthermore, Cu EP has the advantages of high polishing rate, low waste stream, no abrasive and no scratching. It can produce a clean and scratch-free Cu surface. In this thesis, the electrochemical behaviors and micro-leveling mechanism of Cu EP are studied. Organic acid additives are also used to achieve “super-polishing” in wafer processing.
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