Xin Ping Qu received the B.S. degree in solid state electronics from Huazhong University of Science and technology in 1993, the M.S. degree from Shanghai institute of Ceramics, Chinese Academy of Science in 1996, and the Ph.D. degree in solid state electronics and microelectronics from Fudan University, Shanghai in 1999. Since 2006, she becomes a professor in the same department. She is currently with the School of microelectronics, Fudan University, Shanghai. Her research interest includes novel interconnect technology, such as non-copper conductor, 3D interconnect technology, CMP and post-CMP cleaning, electroplating, high aspect ratio metal filling, etc. She has published more than 150 papers in the refereed journals and international conferences. She served as program Co- chair or organization Co-chair for many international conferences. She is currently vice director of Chinese CMP user group. She is now IEEE senior member.
Three-dimension (3D) integration with TSV technology has been regarded as a promising way to overcome the limitation of Moore’s law. The conventional physical vapor deposition (PVD) has shown difficulty in depositing the conformal barrier/liner and Cu seed layer in high aspect ratio (HAR) TSV. Other alternative methods such as chemical vapor deposition (CVD) and atomic layer deposition (ALD) are both based on the high-temperature and high-cost process to obtain the conformal film. Electroless deposition (ELD) technology is a robust candidate to replace the PVD in the HAR TSV metallization owing to its advantages of conformal film coverage and low cost. Co has been considered as an excellent liner material because of its better wettability with Cu and lower resistivity than Ta. The application of the ELD pure Co layer in TSV has not been reported. In this presentation, we demonstrated a wet processes flow for HAR TSV metallization. The ELD Co liner and alkaline electroplating deposited Cu seed layer are successfully integrated into a 4 μm×50 μm TSV. The ELD Co film can have a low resistivity of 13.6 μΩ·cm, due to high metallic Co purity of about 99.4%. The Co liner layer with a step coverage of up to 98% is formed on the TiN barrier in the TSV followed by a conformal alkaline Cu seed layer with step coverage of 75%. Finally, the TSV is filled without voids by the acidic Cu electroplating. This work demonstrates the feasibility of the wet processes flow of conformal liner and seed layer in the HAR TSV.