Tapered electrode in an acoustic resonator
First Claim
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1. An apparatus, comprising:
- an electrode including a tapered end, wherein the tapered end has an angle between approximately five and thirty degrees; and
a piezoelectric material of an acoustic resonator disposed over the electrode.
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Abstract
An apparatus and method to provide a tapered electrode in an acoustic resonator. A piezoelectric (PZ) layer, such as Aluminum Nitride (AIN), is formed over a bottom electrode having a tapered end. A top electrode is positioned on the PZ layer. The tapered end of the bottom electrode creates a mild topography to the under layer of the PZ material to prevent cracking in the PZ layer. The tapered end also decreases acoustic losses in the acoustic resonator because the PZ grains are highly oriented. In one embodiment, the acoustic resonator is a film bulk acoustic resonator (FBAR).
80 Citations
21 Claims
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1. An apparatus, comprising:
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an electrode including a tapered end, wherein the tapered end has an angle between approximately five and thirty degrees; and
a piezoelectric material of an acoustic resonator disposed over the electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A film bulk acoustic resonator (FBAR), comprising:
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a bottom electrode including a tapered end;
a piezoelectric layer layered on the bottom electrode, wherein a surface area of the bottom electrode is less than a surface area of the piezoelectric layer; and
a top electrode positioned on top of the piezoelectric layer wherein at least a portion of the piezoelectric layer is disposed between the bottom electrode and the top electrode. - View Dependent Claims (10, 11, 12)
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13. A method, comprising:
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forming a metal layer on top of a dielectric layer;
placing a photoresist layer on top of the metal layer; and
shaping the metal layer to form a tapered electrode of an acoustic resonator, wherein shaping the metal layer comprises wet etching the metal layer to form the tapered electrode. - View Dependent Claims (14)
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15. An apparatus, comprising:
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a piezoelectric layer of an acoustic resonator; and
means for preventing cracks in the piezoelectric layer, wherein the means for preventing cracks comprises a bottom electrode including a tapered end positioned under the piezoelectric layer. - View Dependent Claims (16, 17, 18)
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19. A system, comprising:
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a film bulk acoustic resonator (FBAR) filter, comprising;
a bottom electrode including a tapered end, wherein the tapered end has an angle between approximately five and thirty degrees; and
a piezoelectric material layered on the bottom electrode; and
a transmitter electrically coupled to the FBAR filter. - View Dependent Claims (20, 21)
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Specification