Wafer bonding of GaAs, InP, and Si annealed without hydrogen for advanced device technologies

Low Temperature Wafer Bonding

“…Then, after 24hours at room temperature, surface energy above 1.6J/m² (in fact, non measurable) has been found without any post bonding thermal treatment. In the same way, Roberds et al [2] report that using in-situ plasma activation, 1J/m² could be obtained at room temperature and that the surface energy was even non measurable after 5mn at 100°C. Indeed, using in-situ activation and bonding, a minimum of water should be present at the wafer surface by avoiding even the air moisture to reach the activated surface.…”

“…figure 11). Water and/or -O-H species diffuse through the native oxide and react with silicon to form additional silicon oxide with the following reaction [2]. This mechanism explains also the native oxide increasing as shown on figure 10.…”

“…Therefore, only the bonding energy needs to be improved during the low temperature process. In the first part of this paper, a quick overview presents different bonding process leading to high bonding energy at low temperature [1,2]. Concerning the bonding of thin/ultra-thin oxide layers or the SDB, bubble generation at bonding interface upon post bonding thermal treatments remains one of the main problems [3] (cf.…”