Patent ID: 8653642

Claim:
A three dimensional stack of active MEMS devices, the stack comprising: a first substrate, the first substrate having: a mounting surface, an active MEMS device on the mounting surface, a plurality of pads formed on the mounting surface, and a back surface facing away from the mounting surface; a second substrate, the second substrate having: a mounting surface, an active MEMS device on the mounting surface, a plurality of pads formed on the mounting surface, and a back surface facing away from the mounting surface; a third substrate, the third substrate having: a mounting surface, an active MEMS device on the mounting surface, and a plurality of pads formed on the mounting surface, wherein the back surface of the second substrate is abutting and bonded to the back surface of the first substrate, wherein the mounting surface of the second substrate is facing the mounting surface of the third substrate, wherein the pads on the mounting surfaces of the second and third substrates are positioned to overlie each other; and solder joining the pads on the second and third substrates bonding the first and second substrates to the third substrate.