Copper (Cu) is a widely used interconnection material in high density ICs, large area TFT LCDs etc. CMP is a production method used in etching Cu fine lines in ICs. Although plasma etching is widely used in preparing small geometry aluminum and other metal lines, it cannot be used to etch Cu at room temperature due to the low volatility of copper halides. A plasma-based high-rate, room-temperature Cu etch process was invented by Kuo's group. It includes the plasma/Cu reaction followed with a dilute HCl dipping step. This process has been successfully demonstrated on BiCMOS and TFT LCD products. The electromigration (EM) method has been used in the evaluation the reliability of Cu lines. Recently, the authors have reported that copper oxide (CuO_x) is a potential useful passivation material for Cu line. In this study, layer thickness effects of Cu and CuO_x passivation films on the reliability are studied.
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