Formation of silicon structures by plasma-activated wafer bonding

A room temperature wafer bonding process based on oxygen plasma treatment o r argon plasma treatment has been studied for surfaces of silicon, silicon dioxide, and crystalline quartz. The surface energy of the bonded samples w as observed at different storage times. Atomic force microscope measurement s, multiple internal reflection infrared spectroscopy, electrical character ization, secondary ion mass spectroscopy, and post-processing steps were pe rformed to evaluate the plasma-treated surfaces and the formed bonded inter faces. Electrical measurements were used to investigate the usefulness of p lasma-bonded interfaces for electronic devices. The bonded interfaces exhib it high surface energies, comparable to what can be achieved with annealing steps in the range of 600-800 degrees C using normal wet chemical activati on before bonding. The high mechanical stability obtained after bonding at room temperature is explained by an increased dynamic in water removal from the bonded interface allowing covalent bonds to be formed. (C) 2000 The El ectrochemical Society.