Acoustic crosstalk reduction for capacitive micromachined ultrasonic transducers in immersion
View Patent ↗A reduced crosstalk capacitive micromachined ultrasonic transducer (CMUT) array is provided. The CMUT array has at least two CMUT array elements deposited on a substrate, at least one CMUT cell in the array element, a separation region between adjacent CMUT array elements, and a membrane formed in the separation region. The membrane reduces crosstalk between adjacent array elements, where the crosstalk is a dispersive guided mode of an ultrasonic signal from the CMUT propagating in a fluid-solid interface of the CMUT array. Each cell has an insulation layer deposited to the substrate. A cell membrane layer is deposited to the insulation layer, where the cell membrane layer has a vacuum gap therein. The cells further have an electrode layer deposited to a portion of the membrane layer, and a passivation layer deposited to the electrode layer, the cell membrane layer and to the insulation layer.
1. A reduced crosstalk capacitive micromachined ultrasonic transducer (CMUT) array comprising:
a. at least two CMUT array elements deposited on a substrate;
b. at least one CMUT cell in said array element;
c. a separation region between adjacent said CMUT array elements; and
d. a membrane formed in said separation region, whereby said membrane reduces crosstalk between said adjacent array elements, whereas said crosstalk comprises a dispersive guided mode of an ultrasonic signal from said CMUT propagating in a fluid-solid interface of said CMUT array.
2. The CMUT array of claim 1 , wherein all said separation regions between said elements are substantially the same, whereby forming a substantial periodicity of said CMUT elements within said CMUT array.
3. The CMUT array of claim 2 , wherein said periodicity of said array elements is in one dimension.
4. The CMUT array of claim 2 , wherein said periodicity of said array elements is in two dimensions.
5. The CMUT array of claim 1 , wherein all said membranes in said separation regions are substantially the same, whereby forming a substantial periodicity of said CMUT elements within said CMUT array.
6. The CMUT array of claim 1 , wherein all said CMUT cells within said elements are substantially the same, whereby forming a substantial periodicity of said CMUT cells within said CMUT element.
7. The CMUT array of claim 1 , wherein said CMUT operates in a conventional mode or a collapsed mode to transmit and receive ultrasound.
8. The CMUT array of claim 1 , wherein said CMUT cell comprises:
a. an insulation layer deposited to said substrate;
b. a cell membrane layer deposited to said insulation layer, wherein said cell membrane layer has a gap therein;
c. an electrode layer deposited to said membrane layer, wherein said electrode layer covers a portion of said membrane layer; and
d. a passivation layer, wherein said passivation layer is deposited to;
i. said electrode layer;
ii. said cell membrane layer; and
iii. said insulation layer.
9. The CMUT array of claim 8 , wherein said CMUT cell has a geometry selected from a group consisting of circular, square, hexagonal and tented.
10. The CMUT array of claim 8 , wherein said insulation layer is a layer selected from a group consisting of silicon nitride and silicon oxide.
11. The CMUT array of claim 8 , wherein said membrane layer is a layer selected from a group consisting of silicon nitride and silicon oxide.
12. The CMUT array of claim 8 , wherein said electrode layer is a layer selected from a group consisting of aluminum and gold.
13. The CMUT array of claim 8 , wherein said passivation layer is a layer selected from a group consisting of silicon nitride and silicon oxide.
14. The CMUT array of claim 8 , wherein said gap is a vacuum gap.