US Patent 7659150 Microshells for multi-level vacuum cavities

Microshells for encapsulation of devices such as MEMS and microelectronics. In an embodiment, the microshells include a planar perforated pre-sealing layer, below which a non-planar sacrificial layer is accessed, and a sealing layer to close the perforation in the pre-sealing layer after the sacrificial material is removed. The sealing layer may include a nonhermetic layer to physically occlude the perforation and a hermetic layer over the nonhermetic occluding layer to seal the perforation as a function of the dimension of the perforation to form cavities having different vacuum levels on the same substrate.