Chemical Investigations of the GsAs to Borosilicate Glass Wafer Bonded Interface

摘要

Wafer bonding is the process of contacting two flat, smooth, and chemically compatible surfaces to form a bond across the interface. To a large extent, studies of the bonding process have focused on the use of SiO_2 and Si that have been treated to produce hydrophilic surfaces. ~1 In this case, the bond that forms across the interface involves hydrogen bonded H_2O and OH groups at room temperature that evolve during high temperature annealing to covalent Si-O bonds. ~2 The use of doped oxides, such as xB_2O_3 centre dot SiO_2 (BSG), and different semiconductors, such as GaAs, provides even greater flexibility in engineering the properties of the resulting bonded structure. For example, the B_2O_3 content in a borosilicate glass (BSG) controls the viscosity and thermal expansion coefficient (TEC) of the bonding medium. BSG has been investigated in the development of a glass-bonded compliant substrate. ~3 The fabrication of these structures for wafer bonding or compliant substrate applications would be enhanced by a detailed knowledge of the chemistry occurring at the semiconductor-to-BSG wafer bonded interface.The interfacial chemistry of the GaAs-to-BSG coated GaAs bonded wafer pair was probed by multiple internal transmission Fourier transform infrared (MIT-FTIR) spectroscopy. ~2 In this technique, polarized light is introduced into a beveled edge of bonded sample, schematically shown in Fig. 1, transmitted through the bonded interface several times, and detected after exiting the sample. This technique has been used with great success in probing the chemistry of the Si wafer bonded interface. ~2