Direct bonding of silicon wafers with the concurrent formation of diffusion layers

An original technique for Si-Si direct bonding combined with impurity diffu sion in a single process is suggested. A dopant (aluminum) source is locate d at the interface. The high-temperature treatment of the polished wafers i n an oxidizing atmosphere results in the diffusion of Al atoms and the form ation of a p-n junction in n-silicon. The presence of aluminum is shown to improve the continuity of the interface. Results obtained are explained wit hin a model whereby the initial contact between the hydrophilic silicon sur faces in a water solution of aluminum nitrate Al(NO3)(3) serves to increase the bonding area of the wafers at room temperature due to the interaction of Al-OH groups with water molecules adsorbed on the surfaces of the wafers . (C) 2001 MAIK "Nauka/Interperiodica".