Fabrication of a hermetic sealing device using low temperature intrinsic-silicon/glass bonding

We propose a novel fabrication methodology for a hermetic sealing device using O₂ plasma-assisted low temperature bonding technique of I-Si and glass. Glass substrates were used as cap and base wafers, while I-Si was selectively applied to the contact surface of the cap wafer as an interlayer. A cavity of above 180 μm in depth was formed in the cap glass by means of wet etching using double layer (photoresist/I-Si) etching mask. I-Si/glass bonding was conducted at 200 °C through the use of I-Si layer-covered glass wafer and bare glass wafer. A tensile test revealed that bonding strength was drastically increased by using O₂ plasma treatment. In addition, scanning acoustic microscope (SAM) observation showed that I-Si/glass bonding was successfully achieved without significant voids. From these results, we believe that the proposed method will be a highly promising technology for future functional hermetic sealing devices.