Stacked semiconductor structure and method of forming the same

A stacked semiconductor structure comprising:

• a complementary metal oxide semiconductor (CMOS) device, the CMOS device comprising:
• an interconnect disposed over a first substrate,
• a first electrode set disposed over the interconnect, and
• first bonding features over the first electrode set;
• and
• a microelectromechanical systems (MEMS) device, the MEMS device comprising:
• a cavity extending upward from a first surface of a second substrate into a first depth of the second substrate, the first depth being less than the thickness of the second substrate,
• a dielectric membrane interposed between the cavity and a movable element of the MEMS device,
• a second electrode set embedded in the movable element between the dielectric membrane and a cap dielectric layer;
• and
• second bonding features interposed between the cap dielectric layer and the first bonding features, the second bonding features bonded to the first bonding features, wherein the first electrode and the second electrode construct a capacitor having a variable capacitance.

A stacked semiconductor structure comprising:

• a first dielectric layer disposed on a first surface of a first substrate;
• a plurality of metal segments disposed on the first dielectric layer, a first metal segment of the plurality of metal segments disposed at a perimeter of a cavity and extending toward the cavity and over the cavity;
• a rigid dielectric layer disposed on the plurality of metal segments;
• a plurality of metal units disposed on the rigid dielectric layer, a first metal unit of the plurality of metal units disposed at a perimeter of the cavity, the first metal unit having a first section running on the rigid dielectric layer, and a second section extending through the rigid dielectric layer and contacting the first metal segment, the second section contacting a first connection pillar;
• a cap dielectric layer disposed on the plurality of metal units, the cap dielectric layer having a first section running on the first metal unit over the rigid dielectric layer and a second section extending through the rigid dielectric layer, the first connection pillar extending through the cap dielectric layer;
• a leg of a movable unit suspended in the cavity, comprising:
• the first dielectric layer,
• the first metal segment,
• a first section of the rigid dielectric layer,
• the first section of the first metal unit, and
• the first section of the cap dielectric layer;
• a center body of the movable unit suspended in the cavity, comprising:
• the first dielectric layer,
• a second metal segment of the plurality of metal segments,
• a second section of the rigid dielectric layer,
• a second metal unit of the plurality of metal units, and
• the cap dielectric layer;
• a first portion of the cavity extending from the first surface of the first substrate into a first depth in the first substrate, the cavity extending laterally under a portion of the first dielectric layer;
• a complementary metal oxide semiconductor (CMOS) device comprising a corresponding connection feature disposed on a first surface of the CMOS device, the corresponding connection feature being bonded to the first connection pillar;
• and
• a second portion of the cavity comprising a space formed between the CMOS device and the cap dielectric layer.