Investigation of Asymmetry Hybrid Bonding Using Cu/Sn & Cu/Cu Bonding with Polyimide for 3D Heterogeneous Integration Applications

• Main Authors: Huang, Yen-Jun, 黃諺鈞
• Other Authors: Chen, Kuan-Neng
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/y47qtk

碩士 === 國立交通大學 === 電子研究所 === 105 === Wafer bonding technology plays an important role to pursue small form factor and high performance for 3D integration. However, in order to achieve high density 2.5D/3D integration, the dimension and pitch of micro bumps continue to scale down. It becomes more and more difficult to fill the narrow gaps with underfill material after bonding. Hybrid bonding technique combining metal and polymer can achieve simultaneous formation of electrical interconnection and mechanical support. Photosensitive polymer is used to fill the gaps between the metal lines through the process of lithography. In addition, chemical mechanical polishing or fly cutting process, which is a conventional way of removing the residue on metals, can be skipped and replaced by the development of exposed polymer. Two types of hybrid bonding platforms are successfully developed in this thesis. The first one is “metal first” hybrid bonding combined with solder bonding. Solder may be affected during the curing process of polymer. Thus an asymmetry hybrid bonding structure is proposed to overcome this issue. The second topic is “polymer first” hybrid bonding combined with Cu/Cu bonding. Polyimide is coated and cured on the bottom wafer before metal sputtering to avoid copper oxidation at high temperature. Metal and polymer can be well bonded simultaneously with wide integration flexibility through various polymer to metal thickness ratios. The mechanical strength of bonded structure is substantially improved with the good use of polymer bonding filling in the extra areas between metal lines. Both of the hybrid-bonded structures show good electrical characteristics and pass several reliability tests. With the advantages of dielectric photosensitivity, excellent bonding qualities, high process flexibilities, strong mechanical strength, good electrical performance and high stability after the reliability tests, these two hybrid bonding structures have the outstanding potential to be used in future 3D heterogeneous applications.