Passivated micromechanical resonators and related methods
First Claim
Patent Images
1. A micromechanical resonator, comprising:
- a micromechanical resonating structure comprising a piezoelectric active layer;
a first electrode disposed on a first side of the piezoelectric active layer;
a patterned second electrode disposed on a second side of the piezoelectric active layer so that the piezoelectric active layer is between the first electrode and the second electrode, the patterned second electrode being polycrystalline; and
a passivation structure formed on the patterned second electrode and configured to inhibit external contaminants from entering grain boundaries of the patterned second electrode,wherein the piezoelectric active layer comprises a piezoelectric material and wherein the passivation structure comprises the piezoelectric material.
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Abstract
Passivated micromechanical resonators and related methods are described. Applicants have appreciated that polycrystalline conductive layers used as electrodes for some MEMS resonators are a source of mechanical and electrical instability. To inhibit or prevent contamination of such conductive layers, which may exacerbate the instabilities, passivation structures are used. The passivation structures can be grown, deposited, or otherwise formed.
47 Citations
20 Claims
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1. A micromechanical resonator, comprising:
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a micromechanical resonating structure comprising a piezoelectric active layer; a first electrode disposed on a first side of the piezoelectric active layer; a patterned second electrode disposed on a second side of the piezoelectric active layer so that the piezoelectric active layer is between the first electrode and the second electrode, the patterned second electrode being polycrystalline; and a passivation structure formed on the patterned second electrode and configured to inhibit external contaminants from entering grain boundaries of the patterned second electrode, wherein the piezoelectric active layer comprises a piezoelectric material and wherein the passivation structure comprises the piezoelectric material. - View Dependent Claims (2)
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3. A micromechanical resonator, comprising:
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a micromechanical resonating structure comprising a piezoelectric active layer; a first electrode disposed on a first side of the piezoelectric active layer; a patterned second electrode disposed on a second side of the piezoelectric active layer so that the piezoelectric active layer is between the first electrode and the second electrode, the patterned second electrode being polycrystalline; and a passivation structure formed on the patterned second electrode and configured to inhibit external contaminants from entering grain boundaries of the patterned second electrode, wherein the piezoelectric active layer is configured to exhibit resonance vibration having a wavelength λ
, and wherein the passivation structure has a thickness h given by 0.00001≦
h/λ
≦
0.1. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A micromechanical resonator, comprising:
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a micromechanical resonating structure comprising a piezoelectric active layer; a first electrode disposed on a first side of the piezoelectric active layer; a patterned second electrode disposed on a second side of the piezoelectric active layer so that the piezoelectric active layer is between the first electrode and the second electrode, the patterned second electrode being polycrystalline; and a passivation structure formed on the patterned second electrode and configured to inhibit external contaminants from entering grain boundaries of the patterned second electrode, wherein the resonator has a total thickness hres and wherein the passivation structure has a thickness h given by 0.00001≦
h/hres≦
0.1. - View Dependent Claims (11)
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12. A micromechanical resonator, comprising:
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a micromechanical resonating structure comprising a piezoelectric active layer; a first electrode disposed on a first side of the piezoelectric active layer; a patterned second electrode disposed on a second side of the piezoelectric active layer so that the piezoelectric active layer is between the first electrode and the second electrode, the patterned second electrode being polycrystalline; and a passivation structure formed on the patterned second electrode and configured to inhibit external contaminants from entering grain boundaries of the patterned second electrode, wherein the patterned second electrode is formed of a first material, wherein the passivation structure is formed of the first material and has a polycrystalline structure, and wherein grain boundaries of the patterned second electrode do not substantially align with grain boundaries of the passivation structure. - View Dependent Claims (13, 14)
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15. A method of fabricating a passivated microelectromechanical resonator, the method comprising:
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forming an active layer of a micromechanical resonating structure; forming a polycrystalline electrode on the active layer; and forming a passivation structure on the polycrystalline electrode having a different crystal configuration than a crystal configuration of the polycrystalline electrode, wherein forming the passivation structure comprises forming the passivation structure of a same piezoelectric material as is used in forming the active layer.
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16. A passivated micromechanical resonator, comprising:
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a substrate; a first electrical pad on the substrate; a second electrical pad on the substrate; a micromechanical resonating structure electrically coupled to the first electrical pad and the second electrical pad and comprising; a layered temperature compensation structure comprising a first layer and a second layer, the layered temperature compensation structure configured to stabilize operation of the micromechanical resonating structure as temperature varies; a bottom electrode disposed on the layered temperature compensation structure; an active layer comprising a piezoelectric material disposed on the bottom electrode; a polycrystalline top electrode disposed on the active layer; and a passivation layer disposed on the polycrystalline top electrode and configured to inhibit contact of external materials with the polycrystalline top electrode; and a first anchor and a second anchor mechanically coupling the micromechanical resonating structure to the substrate. - View Dependent Claims (17, 18)
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19. A method of fabricating a passivated microelectromechanical resonator, the method comprising:
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forming an active layer of a micromechanical resonating structure; forming a polycrystalline electrode on the active layer; and forming a passivation structure on the polycrystalline electrode having a different crystal configuration than a crystal configuration of the polycrystalline electrode, wherein the active layer is configured to support a resonance vibration mode having a wavelength λ
, and wherein forming the passivation structure comprises forming the passivation structure to have a thickness h satisfying the condition 0.00001≦
h/λ
≦
0.1.
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20. A method of fabricating a passivated microelectromechanical resonator, the method comprising:
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forming an active layer of a micromechanical resonating structure; forming a polycrystalline electrode on the active layer; and forming a passivation structure on the polycrystalline electrode having a different crystal configuration than a crystal configuration of the polycrystalline electrode, wherein the polycrystalline electrode is a first electrode and is patterned, and wherein the method further comprises forming a second electrode, wherein the active layer is configured between the first electrode and the second electrode.
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Specification