Wafer-level hermetic packaging technology for MEMS using anodically-bondable LTCC wafer

This paper describes a versatile and reliable wafer-level hermetic packaging technology using an anodically-bondable low temperature cofired ceramic (LTCC) wafer, in which electrical feedthroughs and passive components can be embedded. The hermeticity of vacuum-sealed cavities was confirmed after 3000 cycles of heat shock (-40°C/+150°C, 30 min/30 min) by diaphragm method. The width of seal rings necessary for hermetic sealing of saw-diced chips is 0.1 mm or less. Electrical connection between MEMS on a Si wafer and feedthroughs in the LTCC wafer was established using Sn-containing metal stack simultaneously with anodic bonding. The developed wafer-level hermetic packaging technology is ready for practical applications.