Kang Qiushi, Wang Chenxi, Zhou Shicheng, Li Ge, Lu Tian, Tian Yanhong, He Peng
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.
ACS Appl Mater Interfaces. 2021 Aug 18;13(32):38866-38876. doi: 10.1021/acsami.1c09796. Epub 2021 Jul 28.
Cu/SiO hybrid bonding with planarized dielectric and isolated metal connections can realize ultradense interconnects (e.g., ≤1 μm) by eliminating the microbumps and underfill through the direct bonding of Cu-Cu and SiO-SiO. However, the low-temperature bonding of Cu-Cu (oxide-free surface) and SiO-SiO (hydroxylated surface) is difficult to be compatible in a mechanism. We circumvent this contradiction by constructing a co-hydroxylated functional surface on a Cu/SiO hybrid platform. By combining and optimizing the protocol of Ar/O plasma activation and formic acid solution immersion, an -OH active layer was successfully established on the Cu and SiO surfaces simultaneously, and the increased total surface area provided more adsorption sites for hydroxyl groups. A Cu-Cu interface with sufficient atom diffusion, substantial grain growth, and fewer microvoids was obtained at 200 °C. Notably, the carbon-related interlayer that may degrade the interfacial performance could be effectively inhibited across the optimized SiO-SiO interface even if organic acid was introduced in the protocol. This low-temperature Cu/SiO hybrid bonding via a co-hydroxylated strategy may inspire the development of a memory-centric chip architecture and functional integrated circuits delivering a monolithic-like performance in the future hyperscaling era.
具有平面化电介质和隔离金属连接的铜/二氧化硅混合键合可以通过铜-铜和二氧化硅-二氧化硅的直接键合消除微凸块和底部填充材料，从而实现超密集互连（例如，≤1μm）。然而，铜-铜（无氧化物表面）和二氧化硅-二氧化硅（羟基化表面）的低温键合在机理上难以兼容。我们通过在铜/二氧化硅混合平台上构建共羟基化功能表面来规避这一矛盾。通过结合并优化氩/氧等离子体活化和甲酸溶液浸泡的方案，在铜和二氧化硅表面同时成功建立了-OH活性层，增加的总表面积为羟基提供了更多吸附位点。在200°C下获得了具有足够原子扩散、大量晶粒生长和较少微孔的铜-铜界面。值得注意的是，即使在方案中引入了有机酸，通过优化的二氧化硅-二氧化硅界面也能有效抑制可能降低界面性能的碳相关中间层。这种通过共羟基化策略实现的低温铜/二氧化硅混合键合可能会在未来的超大规模时代激发以存储器为中心的芯片架构和具有类单片性能的功能集成电路的发展。
