A microsystem enclosure for hermetically sealing and thereby protecting a microsystem located on a substrate from the potentially damaging effects of exposure to moisture, dust, and other external environmental or operating conditions. The enclosure broadly comprises a single-piece hermetic cover structure and a single solder preform. The preform facilitates sealing the cover to the substrate in high-temperature, single-step process so as to create a hermetic cavity wherein the microsystem resides.
 The present invention was developed with support from the U.S. government under Contract No. DE-AC04-01 AL66850 with the U.S. Department of Energy. Accordingly, the U.S. government has certain rights in the present invention.