Study of Metallurgical Reactions and Electromigration of 30μm Cu/SnAg/Ni and Cu/SnAg/Cu Microbumps

• Main Authors: Lin, Wan-Hsuan, 林宛萱
• Other Authors: Chen, Chih
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/3yjhkv

碩士 === 國立交通大學 === 工學院加速器光源科技與應用碩士學位學程 === 104 === With intent to satisfy the demand of smaller electric component, the volume of solder continue shrinking. In three-dimensional integrated circuit, the microbump has been adopted to be interconnections between chips. The bump height decrease to 20μm or even lower. In this condition, the solder joint may transform into fully intermetallic compounds (IMCs) joint during electromigration (EM). In this study, we use the SnAg solder bump samples with the dimension of 30μm in width. There are two kinds of under-bump-metallization (UBM) were used: one type is Cu/Sn2.5Ag/Ni/Cu and another is Cu/Sn2.5Ag/Cu. We study the metallurgical reactions at liquid state and solid state. The bumps in the liquid state were reflow at 260°C and the process in the solid state were annealed at 150°C in the oven. In addition, we also conducted EM test in our samples with the current density 8x104 A/cm2. In the reflow and EM process, Cu/Ni system has faster dissolution rate in Copper UBM side than Cu/Cu system. The present of Nickel UBM at the substrate side can facilitate the Copper diffusion from the chip side. The different outcomes have been found in the annealing process. We explain the reasons in each process and also calculate the critical thickness of Copper UBM used in the Cu/Ni system.