Micro-electro-mechanical transducer having an optimized non-flat surface
First Claim
1. A method for a capacitive micromachined ultrasound transducer (cMUT), the method comprising:
- growing and patterning a diffusion barrier layer over a substrate, the diffusion barrier layer having a first area and a second area, the diffusion barrier layer in the first area being patterned to allow a greater level of diffusion penetration of a gas therethrough to form a thermal oxide than a level of diffusion penetration of the gas to form the thermal oxide allowed by the patterning of the diffusion barrier layer at the second area;
performing a diffusion process over the diffusion barrier layer to form the thermal oxide to reach a first depth into the substrate below the first area;
forming an anchor using the thermal oxide, such that the anchor has a lower portion below a major surface of the substrate and an upper portion above the major surface of the substrate; and
forming a membrane layer over the anchor and the substrate, wherein the substrate has a first electrode, the membrane layer has a second electrode opposing the first electrode to define a gap therebetween, and at least one of the membrane layer and the substrate includes a flexible layer, such that the first electrode and the second electrode are movable relative to each other to cause a change of the gap.
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Abstract
A method for a capacitive micromachined ultrasound transducer (cMUT) is provided. The method grows and patterns a diffusion barrier layer over a surface of a base layer. The diffusion barrier layer have different areas that allow different levels of diffusion penetration. A diffusion process is performed over the diffusion barrier layer such that a diffusion reactivated material reaches different depths into the base layer below the different areas. A anchor is formed using the diffusion reactivated material. The anchor has a lower portion below a major surface of the base layer and an upper portion above the major surface of the base layer. A cover layer is placed over the anchor and the base layer. At least one of the cover layer and the base layer includes a flexible layer, such that the cMUT electrodes are movable relative to each other to cause a change of the gap width.
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Citations
20 Claims
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1. A method for a capacitive micromachined ultrasound transducer (cMUT), the method comprising:
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growing and patterning a diffusion barrier layer over a substrate, the diffusion barrier layer having a first area and a second area, the diffusion barrier layer in the first area being patterned to allow a greater level of diffusion penetration of a gas therethrough to form a thermal oxide than a level of diffusion penetration of the gas to form the thermal oxide allowed by the patterning of the diffusion barrier layer at the second area; performing a diffusion process over the diffusion barrier layer to form the thermal oxide to reach a first depth into the substrate below the first area; forming an anchor using the thermal oxide, such that the anchor has a lower portion below a major surface of the substrate and an upper portion above the major surface of the substrate; and forming a membrane layer over the anchor and the substrate, wherein the substrate has a first electrode, the membrane layer has a second electrode opposing the first electrode to define a gap therebetween, and at least one of the membrane layer and the substrate includes a flexible layer, such that the first electrode and the second electrode are movable relative to each other to cause a change of the gap. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for a capacitive micromachined ultrasound transducer (cMUT), the method comprising:
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growing and patterning a diffusion barrier layer over a substrate, the patterned diffusion barrier layer having a first area and a second area, the first area being patterned to allow a greater level of diffusion penetration of a gas therethrough to form an oxide than a level of diffusion penetration of the gas to form the oxide allowed by the patterning of the diffusion barrier layer at the second area; performing a diffusion process over the diffusion barrier layer to form the oxide to reach a first depth into the substrate below the first area, and to reach a second depth into the substrate below the second area, the first depth being greater than the second depth; forming an anchor using the oxide, the anchor having a top portion higher than a surface of the substrate; and forming a membrane layer over the anchor and the substrate, wherein the substrate has a first electrode, the membrane layer has a second electrode opposing the first electrode to define a gap therebetween, and the membrane layer includes a flexible layer, such that the first electrode and the second electrode are movable relative to each other to cause a change of the gap. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification