Bulk acoustic wave resonator
First Claim
1. A resonator comprising:
- a bottom electrode layer;
a top electrode layer which defines a resonator body, the top electrode layer comprising a top electrode comprising a frame region of greater mass per surface area around the periphery of the resonator body and an inner region within the frame region; and
a piezoelectric layer sandwiched between the top and bottom electrode layers to form a stack;
wherein an external region is provided around the outside of the periphery of the resonator body,such that the cutoff frequency of a first resonance mode of the external region is matched to the cutoff frequency of a second, different, resonance mode of the resonator body.
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Abstract
A resonator comprises a bottom electrode layer (12), a top electrode layer (10) which defines a resonator body; and a piezoelectric layer (14) sandwiched between the top and bottom electrode layers. An external region (152) is provided around the outside of the periphery of the resonator body. The cutoff frequency of a first resonance mode of the external region (152) is matched to the cutoff frequency of a second, different, resonance mode of the resonator body. The invention provides a deliberate change (typically increase) in the cutoff frequency the resonance modes in the external region, so that one of the modes has a cutoff frequency close to the cutoff frequency of the fundamental mode of the resonator body.
8 Citations
15 Claims
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1. A resonator comprising:
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a bottom electrode layer; a top electrode layer which defines a resonator body, the top electrode layer comprising a top electrode comprising a frame region of greater mass per surface area around the periphery of the resonator body and an inner region within the frame region; and a piezoelectric layer sandwiched between the top and bottom electrode layers to form a stack; wherein an external region is provided around the outside of the periphery of the resonator body, such that the cutoff frequency of a first resonance mode of the external region is matched to the cutoff frequency of a second, different, resonance mode of the resonator body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of producing a resonator, comprising:
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forming a bottom electrode layer, a top electrode layer which defines a resonator body and a piezoelectric layer sandwiched between the top and bottom electrode layers; forming a frame region of greater mass per surface area around the periphery of the top electrode; and processing an external region around the outside of the periphery of the resonator body such that a cutoff frequency of a first resonance mode of the external region is matched to the cutoff frequency of a second, different, resonance mode of the resonator body. - View Dependent Claims (14, 15)
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Specification