Semiconductor device assembly method and semiconductor device assembly apparatus

Prepared first are a mounting substrate having, on its principal surface, a plurality of recesses which correspond in plan configuration to a plurality of functional chips, and a flat plate disposed on the mounting substrate and having a plurality of confinement regions formed of openings, each of which exposes one of the recesses and a peripheral portion of the recess and is designed to confine one of the functional chips. Next, the functional chips are put into the respective confinement regions on the mounting substrate. The mounting substrate having the functional chips thereon is then immersed in a fluid together with the flat plate. Subsequently, the flat plate immersed in the fluid is displaced (vibrated) with the mounting substrate fixed, thereby fitting the functional chips into the recesses in the mounting substrate.