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US 12,732,155 B1Granted
Temperature stable MEMS resonator
AssigneeSiTime Corporation
InventorsPaul M. Hagelin, Charles I. Grosjean
Life of this patent
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Abstract
A resonant member of a MEMS resonator oscillates in a mechanical resonance mode that produces non-uniform regional stresses such that a first level of mechanical stress in a first region of the resonant member is higher than a second level of mechanical stress in a second region of the resonant member. A plurality of openings within a surface of the resonant member are disposed more densely within the first region than the second region and at least partly filled with a compensating material that reduces temperature dependence of the resonant frequency corresponding to the mechanical resonance mode.
Claims20
An integrated circuit comprising:
- an anchor;
- a first beam and a second beam each extending in parallel along a length dimension “L,” each of the first beam and the second beam having a first end and a swinging end, each of the first beam and the second beam also having a second dimension that is perpendicular to the length dimension;
- a base portion mechanically coupling the anchor and the first end of each beam;
- wherein the anchor is positioned in between the first beam and the second beam at a position, relative to the length dimension “L” of each of the first beam and the second beam, that is intermediate to the first end and the swinging end;
- and
- wherein each of the first beam and the second beam comprises layers, the layers including a silicon crystal layer and a silicon dioxide layer;
- wherein the silicon crystal layer has a first temperature coefficient of Young's Modulus (TCE) at an operating temperature and the silicon dioxide layer has a second TCE that is opposite in sign to the first TCE at the operating temperature;
- wherein the silicon dioxide layer of each of the first beam and the second beam is buried within the respective beam along the second dimension, such that each of the first beam and the second beam has at least one layer on each side of the silicon dioxide layer along the second dimension within the respective beam;
- and
- wherein the second material is hermetically sealed in each of the first beam and the second beam relative to exterior surfaces of the respective first beam or the second beam.
7 more elements
An integrated circuit comprising:
- a die;
- a microelectromechanical systems (MEMS) resonator on the die;
- the MEMS resonator comprising:
- an anchor;
- a first beam and a second beam each having a length that extends along a respective axis, a height perpendicular to the respective axis and a width perpendicular to the respective axis, each of the first beam and the second beam also having a first end and a swinging end;
- and
- a base portion mechanically coupling the anchor and the first end of each beam;
- wherein, for each one of the beams:
- the one of the beams comprises discrete materials, including a first material and a second material;
- the first material has a first temperature coefficient of Young's Modulus (TCE) at an operating temperature of the MEMS resonator and the second material has a second TCE that is opposite in sign to the first TCE at the operating temperature;
- and
- the second material is buried within the one of the beams along at least two of the length, the height and the width of the respective beam;
- and
- wherein the second material is formed as a continuous layer in each of the first beam and the second beam, the continuous layer extending along the respective axis in a manner spanning no more than thirty percent of the length of the respective beam.
11 more elements
An integrated circuit comprising:
- a die;
- a microelectromechanical systems (MEMS) resonator on the die;
- the MEMS resonator comprising:
- an anchor;
- a first beam and a second beam each having a length that extends along a respective axis, a height perpendicular to the respective axis and a width perpendicular to the respective axis, each of the first beam and the second beam also having a first end and a swinging end;
- and
- a base portion mechanically coupling the anchor and the first end of each beam;
- wherein, for each one of the beams:
- the one of the beams comprises discrete materials, including a crystal-silicon-based-material and a second material;
- the crystal-silicon-based-material has a first temperature coefficient of Young's Modulus (TCE) at an operating temperature of the MEMS resonator and the second material has a second TCE that is opposite in sign to the first TCE at the operating temperature;
- and
- the second material is buried within the one of the beams along at least two of the length, the height and the width of the respective beam;
- and
- wherein second material is hermetically sealed in each of the first beam and the second beam relative to exterior surfaces of the respective first beam or the second beam.
11 more elements
Dependencies are inferred from the claim text.