Processes for fabricating capacitive micromachined ultrasonic transducers (CMUTs) are described, as are CMUTs of various doping configurations. An insulating layer separating conductive layers of a CMUT may be formed by forming the layer on a lightly doped epitaxial semiconductor layer. Dopants may be diffused from a semiconductor substrate into the epitaxial semiconductor layer, without diffusing into the insulating layer. CMUTs with different configurations of N-type and P-type doping are also described.

The disclosed subject matter provides thin films including a metal silicide and methods for forming such films. The disclosed subject matter can provide techniques for tailoring the electronic structure of metal thin films to produce desirable properties. In example embodiments, the metal silicide can comprise a platinum silicide, such as for example, PtSi, Pt.sub.2Si, or Pt.sub.3Si. For example, the disclosed subject matter provides methods which include identifying a desired phase of a metal silicide, providing a substrate, depositing at least two film layers on the substrate which include a first layer including amorphous silicon and a second layer including metal contacting the first layer, and annealing the two film layers to form a metal silicide. Methods can be at least one of a source-limited method and a kinetically-limited method. The film layers can be deposited on the substrate using techniques known in the art including, for example, sputter depositing.

A semiconductor device includes a bottom substrate, a sacrificial layer on the bottom substrate and including a first opening exposing a first portion of the bottom substrate and a second opening exposing a second portion of the bottom substrate, a top substrate on the sacrificial layer and on the second opening forming a cavity, a first metal layer on the top substrate and/or on the exposed first portion of the bottom substrate, an adhesive layer on the first metal layer, and a second metal layer on the adhesive layer defining one or more pads. The pad includes a stack-layered structure of a first metal layer on the bottom substrate, an adhesive layer on the first metal layer, and a second metal layer on the adhesive layer. The thus formed structure reduces the pad contact resistance.

An approach includes a method of fabricating a switch. The approach includes forming a fixed electrode, forming a first cantilevered electrode, forming a second cantilevered electrode aligned vertically over the first fixed electrode, and which has an end that overlaps and is operable to directly contact an end of the first cantilevered electrode upon an application of a voltage to the fixed electrode, and forming a hermetically sealed volume encapsulating the first fixed electrode, the second fixed electrode, the first cantilevered electrode, and the second cantilevered electrode.

The disclosed subject matter provides thin films including a metal silicide and methods for forming such films. The disclosed subject matter can provide techniques for tailoring the electronic structure of metal thin films to produce desirable properties. In example embodiments, the metal silicide can comprise a platinum silicide, such as for example, PtSi, Pt.sub.2Si, or Pt.sub.3Si. For example, the disclosed subject matter provides methods which include identifying a desired phase of a metal silicide, providing a substrate, depositing at least two film layers on the substrate which include a first layer including amorphous silicon and a second layer including metal contacting the first layer, and annealing the two film layers to form a metal silicide. Methods can be at least one of a source-limited method and a kinetically-limited method. The film layers can be deposited on the substrate using techniques known in the art including, for example, sputter depositing.

A microphone includes a substrate, an opening extending through the substrate, a first electrode plate layer on the opening, a second electrode plate layer spaced apart from the first electrode plate layer, a support structure layer on the substrate including an electrode attachment portion operable to attach the second electrode plate layer and a stopper operable to block contact between the first electrode plate layer and the second electrode plate layer, a cavity delineated by the support structure layer, the first electrode plate layer, and the substrate, and a conductive material layer on the support structure layer and spaced apart from the second electrode plate layer. The microphone has a significantly lower leakage current than conventional semiconductor microphones.

A vibration transducer includes a silicon substrate, a first oxide film formed on the silicon substrate, an activation layer formed on the first oxide film, a second oxide film formed on the activation layer, a polysilicon layer formed on the second oxide film, and a substrate contact part. A vibrator, a vibrator electrode electrically conducted with the vibrator, a fixed electrode close to the vibrator and a vacuum chamber configured to surround the vibrator are formed in the activation layer. The polysilicon layer forms a shell. The substrate contact part is configured to electrically conduct the polysilicon layer and the silicon substrate, and is formed to continuously surround the vacuum chamber in a region, in which the vibrator, the vibrator electrode and the fixed electrode of the activation layer are not formed, of the activation layer.

An approach includes a method of fabricating a switch. The approach includes forming a first fixed electrode and a second fixed electrode, forming a first cantilevered electrode aligned vertically over the first fixed electrode, forming a second cantilevered electrode aligned vertically over the second fixed electrode, and which has an end that overlaps and is operable to directly contact an end of the first cantilevered electrode upon an application of a voltage to at least one of the first fixed electrode and the second fixed electrode, and forming a hermetically sealed volume encapsulating the first fixed electrode, the second fixed electrode, the first cantilevered electrode, and the second cantilevered electrode.

An approach includes a method of fabricating a switch. The approach includes forming a first fixed electrode and a second fixed electrode, forming a first cantilevered electrode aligned vertically over the first fixed electrode, forming a second cantilevered electrode aligned vertically over the first fixed electrode and which has an end that overlaps the first cantilevered electrode, forming a third cantilevered electrode aligned vertically over the second fixed electrode and operable to directly contact the first cantilevered electrode upon an application of a voltage to the second fixed electrode, and forming a hermetically sealed volume encapsulating the first fixed electrode, the second fixed electrode, the first cantilevered electrode, and the second cantilevered electrode.

An approach includes a method of fabricating a switch. The approach includes forming a first cantilevered electrode, forming a second cantilevered electrode over an electrode and operable to contact the first cantilevered electrode upon an application of a voltage to the electrode, and forming an arm on the first cantilevered electrode with an extending protrusion extending upward from an upper surface of the arm.