MEMS pressure sensor and microphone devices having through-vias and methods of forming same

A device comprising:

• a first chip comprising a conductive layer, wherein the conductive layer provides a first membrane for a first device and a second membrane for a second device different than the first device;
• a second chip bonded to a first side of the first chip by a plurality of eutectic bonds, the second chip comprising:
• a substrate, wherein a top surface of the first membrane is exposed to a pressure level of a first cavity extending into the substrate, and wherein a top surface of the second membrane is exposed to a pressure level of a second cavity extending into the substrate, the first cavity being sealed off from the second cavity by the eutectic bonds;
• and
• a plurality of through vias extending through the substrate;
• and
• a third chip bonded to a second side of the first chip, the second side being opposite the first side, wherein a first opening extending through the third chip exposes a bottom surface of the first membrane to an ambient pressure level.

A device comprising:

• a first chip comprising a conductive layer that provides a first membrane for a first device and a second membrane for a second device;
• a second chip bonded the first chip, the second chip comprising:
• a semiconductor substrate;
• an insulating layer on the semiconductor substrate;
• and
• a plurality of through vias extending through the semiconductor substrate, the insulating layer disposed between the plurality of through vias and the semiconductor substrate along a line perpendicular to a major surface of the semiconductor substrate;
• and
• a third chip bonded to the first chip, the first chip being interposed between the third chip and the second chip, wherein a first opening extending through the third chip exposes a first surface of the first membrane to an ambient pressure level, and wherein a second opening extending through the third chip exposes a second surface of the second membrane to the ambient pressure level.