Improved microelectromechanical systems (MEMS), processes and apparatus using thermocompression bonding are disclosed. For example, process embodiments are disclosed in which wafer-scale as well as die-scale thermocompression bonding is utilized to encapsulate MEMS and/or to provide electrical interconnections with MEMS. Apparatus embodiments include apparatus for performing thermocompression bonding and bonded hybrid structures manufactured in accordance with the process embodiments. Devices having various substrate bonding and/or sealing configurations variously offer the advantage of reduced size, higher manufacturing yields, reduced costs, improved reliability, improved compatibility with existing semiconductor manufacturing process and/or greater versatility of applications.