Methods and systems for capacitive micromachined ultrasonic transducers
AssigneeGE Precision Healthcare LLC
InventorRupak Bardhan Roy
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Abstract
Various methods and systems are provided for a microelectromechanical systems (MEMS) device. In one example, the MEMS device may include a silicon wafer with a first oxide coating, a cavity in the first oxide coating having a substantially flat floor formed of a layer of the first oxide coating and etched to a first depth prior to deposition of a masking layer, and a membrane coupled to the silicon wafer and spaced away from the substantially flat floor of the cavity by a second depth of the cavity. The second depth is a sum of the first depth and a height of a second oxide coating formed at the post regions of the MEMS device after the masking layer is removed from the post regions.
Claims20
A microelectromechanical systems (MEMS) device, comprising:
- a silicon wafer with a first oxide coating;
- a cavity in the first oxide coating having a substantially flat floor formed of a layer of the first oxide coating that is continuous with the first oxide coating at post regions of the MEMS device, the cavity etched to a first depth prior to deposition of a masking layer;
- and
- a membrane coupled to the silicon wafer and spaced away from the substantially flat floor of the cavity by a second depth of the cavity, wherein the second depth is a sum of the first depth and a height of a second oxide coating formed at the post regions of the MEMS device after the masking layer is removed from the post regions.
A method for forming a microelectromechanical systems (MEMS) device, comprising:
- etching a cavity into a first oxide coating of a substrate;
- depositing one or more additional layers onto the substrate, the one or more additional layers including a masking layer deposited onto a bottom of the cavity and post regions around the cavity;
- removing the one or more additional layers from the post regions to form a flush surface between the post regions and a portion of the masking layer remaining on the bottom of the cavity;
- locally oxidizing the post regions to form a second oxide coating over the first oxide coating;
- and
- removing the portion of the masking layer from the cavity to produce a cavity profile with a substantially flat floor.
A capacitive micromachined ultrasonic transducer (CMUT), comprising:
- a substrate having cavities with substantially flat floors continuously coated with an oxide, the cavities having final depths equal to a thickness of a masking layer plus a field oxidation height at post regions of the substrate.
Dependencies are inferred from the claim text.