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|New Thin Adhesive for High Density 2.5D Heterogeneous Device Integration with Cu-Cu Hybrid Bonding|
|Keywords: Thin Adhesive, 2.5D Heterogeneous Device Integration, Cu-Cu Hybrid Bonding|
|Heterogeneous integration of logic, memory, sensor chips on interposer (2.5D) attract much attentions as a candidate for More-than-Moore technology. For the high performance 2.5D devices, high density integration of chips with narrow space and high density interconnection with small pitch bonding electrode are the key technology. In current bonding technology, solder micro-bumps (>20μm diameter) and non-conductive adhesive are adopted. However, there may be some limitations for high density device integration with these technologies because of protrusion of adhesive around chips, thermal sliding at bonding, and limit of solder micro-bump minimization. Hybrid bonding with small Cu electrode (<10 μm diameter) is a strong candidate for the advanced device integration technology. Our goal is to develop a new adhesive which enables no protrusion, no thermal sliding, no void, and high electrical reliability. A spin coating thin adhesive (0.05-2.5 μm thick) was developed. The new adhesive can be cured at 200˚C. The cured adhesive film has no tackiness and optically flat surface. The adhesive film can be temporally bondable to SiO2 at room temperature. After 200˚C baking the permanent bonding is achieved, and there is no degradation of bonding strength and no void even after 400˚C baking. The leakage current of adhesive is 10–10 A/cm2 at E = 1 MV/cm. For the applicability to chip on wafer process, the adhesive film/Si wafer can be divided to chips by blade dicing without no delamination and no apparent particles. After bonding the adhesive/Si chip to bare Si wafer at room temperature, thermal sliding amount after thermal compression process (250˚C, 10min, 1MPa) was less 1 μm (under detection limit) from optical microscopic measurement. In addition, there was no protrusion of adhesive around the chip corner from SEM. A first trial for hybrid bonding is also shown.|
|Dr. Yasuhisa Kayaba,
Mitsui Chemicals, Inc.