Anodic Bonding at Room Temperature

Abstract

Special phosphate glasses (niobium-phosphate glasses) are used for anodic bonding experiments. They are optimized particularly with regard to elevated alkali ion conductivity at room temperature due to high contents of Li or Na ions. The compounds anodically bonded at room temperature show the strength of the breakage of the glass. Only a few seconds up to a few minutes at voltages of maximum 500 V are necessary for bonding. The glasses have a thermal expansion coefficient, which is not fitted to that of silicon. Therefore, stability of the bonded compounds is achieved only at temperature jumps up to 100 K in the case of bulk samples. For higher temperature jumps the probability of breakage increases continuously. It is possible to get thin films of these glasses with ac and dc magnetron sputter techniques for example on silicon. These thin layers are anodically bondable and the compounds with silicon show a higher temperature stability (at least 233 to 473 K).