Monolithic integration of MEMS and IC devices

A device comprising:

• a substrate having first and second surfaces;
• integrated circuit (IC) components disposed on the first surface of the substrate;
• a back-end-of-line (BEOL) dielectric disposed on the first surface of the substrate, the BEOL dielectric covering the IC components, wherein the BEOL dielectric comprises
• a plurality of interlevel dielectric (ILD) levels with contacts and interconnect lines for interconnecting the IC components, and
• a pad level on an uppermost ILD level, the pad level comprises IC interconnect pads;
• and
• a micro electromechanical system (MEMS) disposed over a top of the BEOL dielectric with the IC interconnect pads, wherein the MEMS comprises
• a MEMS stack, the MEMS stack is disposed directly on the top of the BEOL dielectric, the MEMS stack having a top MEMS surface and a bottom MEMS surface, wherein the MEMS stack includes
• an active MEMS layer having a top active MEMS layer surface and a bottom active MEMS layer surface,
• a patterned top MEMS electrode disposed on the top active MEMS layer surface, and
• a patterned bottom MEMS electrode disposed on the bottom active MEMS layer surface, and
• IC MEMS contacts, wherein the IC MEMS contacts line IC MEMS contact vias which are disposed at least partially through the active MEMS layer, wherein
• the IC MEMS contact vias extend completely through the MEMS stack to expose top surfaces of the interposer contacts, and
• the IC MEMS contacts directly contact the IC interconnect pads.

A method of forming a device, comprising:

• providing a substrate with first and second surfaces, the substrate is prepared with integrated circuit (IC) components on the first surface of the substrate and a back-end-of-line (BEOL) dielectric formed over the first surface of the substrate with at least one interlevel dielectric (ILD) level with interconnects and contacts coupled to the IC components;
• forming a pad level on an uppermost ILD level, the pad level comprises IC interconnect pads coupled to the IC components via the at least one ILD level;
• forming a micro electromechanical system (MEMS) stack over the pad level, the MEMS stack includes
• a MEMS region having a MEMS component with MEMS electrodes and MEMS contacts coupled to the MEMS electrodes, and
• an IC region over the IC interconnect pads, the IC region includes IC MEMS contacts configured to be coupled to the IC interconnect pads;
• forming a planar encapsulation layer over the MEMS stack, including the IC and MEMS regions;
• and
• forming MEMS solder bumps and IC solder bumps in the encapsulation layer, wherein the MEMS solder bumps are coupled to the MEMS contacts and the IC solder bumps are coupled to the IC MEMS contacts.