Simultaneous fabrication of dielectric and electrical joints by wafer bonding

Wafer bonding is a key technology for the fabrication of micro mechanical systems which consist of two or more stacked silicon parts. Among the different bonding methods anodic bonding with an intermediate layer of Pyrex glass offers several advantages concerning the process flexibility and the stability of the bond. To use this technology the sputter deposition process of Pyrex glass was optimized and the anodic bonding process was characterized. A process for a capacitive pressure sensor was designed which included bond frames made out of sputtered glass. The electrical contact from both electrodes to contact pads was realized by lateral and vertical feedthroughs. The later ones were obtained by an Au-Au thermocompression bond which was simultaneously fabricated with the anodic bond.