Microelectromechanical button device and corresponding waterproof user interface element

A user interface element, comprising:

• a case having a deformable portion;
• and
• a microelectromechanical button device including:
• a substrate of semiconductor material with a front surface and a rear surface, which have an extension in a horizontal plane and are opposite to one another along a vertical axis, orthogonal to the horizontal plane;
• a buried electrode on the substrate;
• a structural layer including a mobile electrode overlying the substrate and elastically suspended above the buried electrode at a separation distance so as to form a detection capacitor;
• and
• a cap coupled to the structural layer and having a first main surface facing the structural layer and a second main surface opposite to the first main surface along the vertical axis, is the cap being designed to be mechanically coupled to the deformable portion of the case,
• wherein the cap has, on the first main surface, an actuation portion on the mobile electrode and configured so as to cause, in the presence of a pressure applied on the second main surface, a deflection of the mobile electrode towards the buried electrode, the deflection configured to cause a capacitive variation of the detection capacitor, the capacitive variation being indicative of an actuation of the microelectromechanical button device.

An electronic apparatus, comprising:

• a case having a deformable portion;
• and
• a user interface element that defines a physical button, the user interface element having a microelectromechanical button device including:
• a substrate of semiconductor material with a front surface and a rear surface, which have an extension in a horizontal plane and are opposite to one another along a vertical axis, orthogonal to the horizontal plane;
• a buried electrode on the substrate;
• a structural layer including a mobile electrode overlying the substrate and elastically suspended above the buried electrode at a separation distance so as to form a detection capacitor;
• and
• a cap coupled to the structural layer and having a first main surface facing the structural layer and a second main surface opposite to the first main surface along the vertical axis, is the cap being designed to be mechanically coupled to the deformable portion of the case,
• wherein the cap has, on the first main surface, an actuation portion on the mobile electrode and configured so as to cause, in the presence of a pressure applied on the second main surface, a deflection of the mobile electrode towards the buried electrode, the deflection configured to cause a capacitive variation of the detection capacitor, the capacitive variation being indicative of an actuation of the microelectromechanical button device.

A process for manufacturing of a microelectromechanical button device, the process comprising:

• forming a buried electrode, via definition of a conductive layer, on a substrate of semiconductor material, the substrate having a front surface and a rear surface, which have an extension in a horizontal plane and are opposite to one another along a vertical axis, orthogonal to the horizontal plane;
• forming a mobile electrode, via definition of a structural layer, overlying the substrate, and elastically suspended above the buried electrode at a separation distance so as to form a detection capacitor;
• coupling a cap to the structural layer, the cap having a first main surface that faces the structural layer and a second main surface, opposite to the first main surface along the vertical axis, the cap being designed to be mechanically coupled to a deformable portion of a case of an electronic apparatus;
• and
• forming an actuation portion of the cap, at the first main surface, the actuation portion being arranged over the mobile electrode and being configured to cause, in the presence of a pressure applied on the second main surface, a deflection of the mobile electrode towards the buried electrode, the deflection configured to cause a capacitive variation of the detection capacitor, the capacitive variation being indicative of an actuation of the microelectromechanical button device.