Interface fracture surface energy of sol-gel bonded silicon wafers by three-point bending
Résumé
To probe the interface of silicon sol-gel bonded wafers we developed in-situ micromechanical bending test coupled with optical microscopy. The silicon wafers were bonded together at room temperature using sol-gel silica and dried at 60 oC and sintered at 600 oC. Beam specimens were cut from the bonded wafers, then notched and tested in three-point bending. During bending the crack opening from a notch and the deviation along the interface was observed with an optical microscope. To quantify the interfacial debonding from considering the experimental results, a simple energy balance allows an apparent inter- facial fracture surface energy to be determined. Experi ments and the determined interfacial surface energies show that the bonding of the silicon wafers depends on the silica sol-gel chemistry and on the temperature of the thermal treatment during the bonding process.