Hydrophobic low temperature wafer bonding; void formation in the oxide free interface

Paper in proceeding, 2003

The objective is to investigate plasma assisted bonding processes having the potential of forming oxide-free bonded interfaces. Spontaneous low temperature hydrophobic bonding was achieved using a plasma-assisted technique. High surface energy was obtained when bonding two silicon wafers after argon plasma treatment and a subsequent dip in concentrated HF. In contrast hydrogen plasma caused bonding problems while a mix of hydrogen and nitrogen improved the bondability. A particular interest is directed toward the generation of voids as a consequence of storage at room temperature or low temperature annealing. All samples suffer from void generation both after storage at room temperature and after low temperature annealing.