Method of epitaxial-like wafer bonding at low temperature and bonded structure

摘要

A process for bonding oxide-free silicon substrate pairs and other substrates at low temperature. This process involves modifying the surface of the silicon wafers to create defect regions, for example by plasma-treating the surface to be bonded with a or boron-containing plasmas such as a B₂H₆ plasma. The surface defect regions may also be created by ion implantation, preferably using boron. The surfaces may also be amorphized. The treated surfaces are placed together, thus forming an attached pair at room temperature in ambient air. The bonding energy reaches approximately 400 mJ/m² at room temperature, 900 mJ/m² at 150° C., and 1800 mJ/m² at 250° C. The bulk silicon fracture energy of 2500 mJ/m² was achieved after annealing at 350-400° C. The release of hydrogen from B-H complexes and the subsequent absorption of the hydrogen by the plasma induced modified layers on the bonding surfaces at low temperature is most likely responsible for the enhanced bonding energy.