Plasma assisted room temperature bonding for MST

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 wa s measured after different storage times at room temperature. After 24 h th e bonded interfaces exhibit high surface energies, comparable to what can b e achieved with annealing steps in the range of 600-800 degreesC using norm al wet chemical activation before bonding Subsequent annealing of the bonde d silicon/silicon samples caused substantial generation of voids while void generation did not occur in bonded silicon dioxide/silicon dioxide samples . The void generation is influenced by process parameters such as the chamb er pressure and the coil. The silicon/silicon interfaces formed at room tem perature show electrical properties comparable to those of bonded silicon/s ilicon interfaces formed using wet chemical activation and high temperature annealing. (C) 2001 Elsevier Science B.V. All rights reserved.