Suetsugu Naoki, Iwase Eiji
School of Fundamental Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
Micromachines (Basel). 2023 Feb 18;14(2):475. doi: 10.3390/mi14020475.
This study clarifies the conditions for the bridging and conduction of a gap on a metal interconnect using copper microparticles dispersed with silicon oil. An AC voltage applied to a metal interconnect with a gap covered by a dispersion of metal microparticles traps the metal microparticles in the gap owing to the influence of a dielectrophoretic force on the interconnect, thus forming a metal microparticle chain. The current was tuned independently of the applied voltage by changing the external resistance. An AC voltage of 32 kHz was applied to a 10 µm wide gap on a metal interconnect covered with 3 µm diameter copper microparticles dispersed with silicone oil. Consequently, the copper microparticle chains physically bridged the interconnect and exhibited electrical conductivity at an applied voltage of 14 V or higher and a post-bridging current of 350 mA or lower. It was shown that the copper microparticle chains did not exhibit electrical conductivity at low applied voltages, even if the microparticle chains bridged the gap. A voltage higher than a certain value was required to achieve electrical conductivity, whereas an excessive voltage caused bubble formation and destroyed the bridges. These phenomena were explained based on the applied voltage and reference value of the current after bridging.
本研究阐明了使用分散在硅油中的铜微粒实现金属互连上间隙的桥接和传导的条件。施加到带有由金属微粒分散体覆盖的间隙的金属互连上的交流电压，由于介电泳力对互连的影响，会将金属微粒捕获在间隙中，从而形成金属微粒链。通过改变外部电阻，可独立于施加电压来调节电流。将32kHz的交流电压施加到覆盖有分散在硅油中的直径为3μm的铜微粒的金属互连上的10μm宽间隙上。结果，铜微粒链在物理上桥接了互连，并且在14V或更高的施加电压以及桥接后350mA或更低的电流下表现出导电性。结果表明，即使微粒链桥接了间隙，铜微粒链在低施加电压下也不表现出导电性。需要高于某个值的电压才能实现导电性，而过高的电压会导致气泡形成并破坏桥接。基于施加电压和桥接后电流的参考值对这些现象进行了解释。
