Development of Low Temperature Bonding Technology for Glass and Polymer Substrates in Ambient Air for Future Three-Dimensional MEMS Packaging

在本研究中，在环境类空气条件下，在150℃下实现了Cu、玻璃（包括SiO2和石英）和聚酰亚胺的homo/heterogeneous键合技术。为了同时与这些材料产生良好的粘结性，使用蒸汽辅助表面活化方法创建了兼容的桥接层。在这种情况下，水蒸气被引入到材料的原子清洁表面，它有助于创造粘合剂水性化合物。桥接层的化学结构和厚度仅随单位面积和时间内与表面碰撞的水分子数量而可调，从而使整个表面具有较高的结合能，同时Cu-Cu界面具有良好的导电性。此外，无铜衬底和聚酰亚胺绝缘体的结合也证明了该工艺的高可行性。

In this study, a homo/heterogeneous bonding technology for Cu, glass (including both SiO2 and quartz), and polyimide was realized at 150 oC in ambient air-like condition. In order to create a good bondability to these materials at the same time, a compatible bridging layer was created with the vapor-assisted surface activation method. In this, water vapor was introduced onto the atomically clean surfaces of materials and it helped create the adhesive aqueous compounds. The chemical structure and thickness of the bridging layers are tunable only with the number of water molecules colliding with the surface in unit area and time, which resulted in high binding energy on entire surface and good electric conduction at Cu-Cu interface at the same time. Moreover, a Cu bumpless substrate and a polyimide insulator was bonded to demonstrate high feasibility of this process.