Integrated acoustic transducer obtained using MEMS technology, and corresponding manufacturing process

A MEMS acoustic transducer comprising:

• a substrate having a cavity;
• membrane anchors:
• a suspended membrane coupled to the substrate by the membrane anchors, the suspended membrane located above said cavity and entirely suspended between the membrane anchors, said suspended membrane being configured to oscillate and including a first through-hole that is entirely surrounded on all sides by the suspended membrane and arranged near a first one of the membrane anchors, the first through-hole being configured to release tension and compression that acts in a direction lying in a same plane as said suspended membrane;
• an electrode arranged at a distance from and facing the suspended membrane, said electode being made of conductive material and forming a capacitor with the central portion of the suspended membrane;
• an insulating plate arranged above said electrode;
• and
• first anti-stiction elements extending through said electrode and projecting beyond said electrode towards said membrane.

An electronic device, comprising:

• a MEMS transducer that includes:
• a substrate having a cavity
• a plurality of membrane anchors;
• and
• a suspended membrane coupled to the substrate by the plurality of membrane anchors, the suspended membrane being suspended above said cavity and detached from the substrate except at the plurality of membrane anchors, the suspended membrane including a through-hole arranged near a first one of the membrane anchors and entirely surrounded on all sides by the suspended membrane, said suspended membrane comprising a second through-hole arranged near a second one of the membrane anchors, wherein each of said first and second through-holes has an elongated shape having a first pair of lateral-delimitation sides having a length between 80 μm and 140 μm, and a second pair of lateral-delimitation sides having a length between 2 μm and 6 μm, said first through-hole being arranged at a distance from the first one of the membrane anchors between 10 μm and 40 μm and said second through-hole being arranged at a distance from the second one of the membrane anchors between 10 μm and 40 μm.

A process, comprising:

• manufacturing a MEMS transducer, the manufacturing including:
• forming a cavity in a substrate;
• forming a plurality of member anchors;
• forming a membrane suspended above the cavity such that the membrane is suspended above the cavity and decoupled from the substrate except at the plurality of member anchors, the suspended membrane being configured to oscillate;
• and
• forming in the suspended membrane a first through-hole arranged near a first one of the membrane anchors and entirely surrounded on all sides by the suspended membrane, said through-hole being configured to release tension and compression acting in a direction lying in a same plane as said suspended membrane,
• wherein forming a cavity comprises defining an initial cavity by etching from a back side of said substrate using a first mask having a first window with a first area, the method further comprising etching from the back side of said substrate using a second mask having a second window with a second area larger than the first area, and simultaneously forming a first chamber having the first area and facing said membrane, and a second chamber commununicating with said first chamber and having the second area.

A MEMS acoustic transducer comprising:

• a substrate having a cavity;
• a membrane suspended above said cavity and including a central region, a peripheral region surrounding the central region, and a first membrane anchorage extending toward the substrate from the peripheral region and fixed to said substrate, said membrane being configured to oscillate and including a first spring arranged near said first membrane anchorage and configured to act in tension and compression in a direction lying in a same plane as said membrane;
• an electrode arranged at a distance from and facing the membrane, said electrode being made of conductive material and forming a capacitor with the central portion of the membrane;
• an insulating plate arranged above said electrode;
• and
• first anti-stiction elements extending through said electrode and projecting beyond said electrode towards said membrane.

A process comprising:

• manufacturing a MEMS transducer, the manufacturing including:
• forming a cavity in a substrate;
• forming a membrane suspended above the cavity and including a central region, a peripheral region surrounding the central region, and a first membrane anchorage extending toward the substrate from the peripheral region and fixed to said substrate, the membrane being configured to oscillate;
• forming in the membrane a first spring arranged near said first membrane anchorage, said spring being configured to act in tension and compression in a direction lying in a same plane as said membrane;
• and
• forming an electrode at a distance from and facing the membrane, said membrane and said electrode being made of conductive material, wherein forming said membrane and said electrode comprises:
• forming a first sacrificial layer on the substrate;
• forming a membrane layer on said first sacrificial layer;
• defining said membrane layer;
• forming a second sacrificial layer on said membrane layer;
• depositing an electrode layer on said second sacrificial layer and defining said electrode layer so as to form an electrode separated from said membrane through said second sacrificial layer;
• removing said first sacrificial layer, so as to suspend said membrane over the substrate;
• and
• partially removing said second sacrificial layer so as to suspend the electrode above the membrane.