Room temperature and zero pressure high quality oxide direct bonding for 3D self-aligned assembly

To keep up with the pace of decreasing transistor channel length, the demand for smaller pitch size is pushing 3D IC research into new approaches for stacking. As the pitch size decreases, the thickness of interconnection also decreases. During stacking, a small misalignment may lead to poor interconnection or even connection failure. This has led 3D IC research to pursue higher alignment accuracy during stacking. One such stacking approach that is being considered is 3D self-alignment. To facilitate highly accurate alignment it is also important to have good quality immediate bonding that can further reduce chances of misalignment during handling. In this work, we demonstrate a very high quality bonding between two similar dies with oxide capping layer, as well as different cleaning approach and the bonding test.