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US 12,445,107 B2Granted
Non-lid-bonded MEMS resonator with phosphorus dopant
AssigneeSiTime Corporation
InventorsCharles I. Grosjean, Ginel C. Hill, Paul M. Hagelin, Renata Melamud Berger, Aaron Partridge, Markus Lutz
Life of this patent
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Abstract
A microelectromechanical system (MEMS) resonator includes a substrate having a substantially planar surface and a resonant member having sidewalls disposed in a nominally perpendicular orientation with respect to the planar surface. Impurity dopant is introduced via the sidewalls of the resonant member such that a non-uniform dopant concentration profile is established along axis extending between the sidewalls parallel to the substrate surface and exhibits a relative minimum concentration in a middle region of the axis.
Claims22
A semiconductor device comprising:
- a substrate;
- a layer stack on the substrate, the layer stack including a lid layer, the lid layer having been conformally deposited over one or more underlying layers of the layer stack, the lid layer having at least one vent, the at least one vent being plugged so as to, in combination with the lid layer, hermetically seal a cavity relative to the substrate, the cavity being defined by etch of one or more oxide layers of the layer stack through the at least one vent prior to the at least one vent being plugged;
- and
- a microelectromechanical system (MEMS) device having a body that is free to vibrate or deflect within the cavity during operation of the semiconductor device, the body formed from one or more layers fabricated from the substrate, wherein at least one layer of the one or more layers has a phosphorus dopant concentration greater than or equal to 1019/cm3;
- wherein the semiconductor device comprises circuitry to (1) receive a signal representing a temperature of operation and a signal representing the resonance frequency, and (2) generate, using the signal representing the temperature of operation and the signal representing the resonance frequency, a timing reference signal, wherein the timing reference signal is to have a reduced proportional variation in frequency relative to a proportional variation in the resonance frequency as a function of change in the temperature of operation of the resonator.
2 more elements
A method of manufacturing a semiconductor device, the method comprising:
- forming a layer stack on a substrate so as to include a lid layer, wherein forming comprises conformally-depositing the lid layer over one or more underlying layers of the layer stack, and wherein forming comprises forming the lid layer so as to have at least one vent;
- forming a cavity within the layer stack and a microelectromechanical system (MEMS) device, the MEMS device having a body that is free to vibrate or deflect, within the cavity, during operation of the semiconductor device;
- wherein forming the MEMS device comprises doping one or more layers of the layer stack to have a phosphorus dopant concentration greater than or equal to 1019/cm3, and forming the body to include the phosphorus dopant concentration greater than or equal to 1019/cm3;
- wherein forming the cavity comprises etching one or more oxide layers of the layer stack through the at least one vent and, subsequently, plugging the at least one vent to hermetically seal the body within the cavity;
- and
- wherein the method further comprises forming the semiconductor device to include circuitry operable to (1) receive a signal representing a temperature of operation and a signal representing the resonance frequency, and (2) generate, using the signal representing the temperature of operation and the signal representing the resonance frequency, a timing reference signal, wherein the timing reference signal is to have a reduced proportional variation in frequency relative to a proportional variation in the resonance frequency as a function of change in the temperature of operation of the resonator.
3 more elements
A method of manufacturing a semiconductor device, the method comprising:
- forming a layer stack on a substrate so as to include a lid layer, wherein forming comprises conformally-depositing the lid layer over one or more underlying layers of the layer stack, and wherein forming comprises forming the lid layer so as to have at least one vent;
- forming a cavity within the layer stack and a microelectromechanical system (MEMS) device, the MEMS device having a body that is free to vibrate or deflect, within the cavity, during operation of the semiconductor device;
- wherein forming the MEMS device comprises conformally depositing a phosphorus-based substance on at least one layer of the layer stack and using a thermal drive-in process to transfer phosphorus from the substance into the at least one layer of the layer stack, to cause the at least one layer of the layer stack to have a phosphorus dopant concentration greater than or equal to 1019/cm3, and forming the body to include the phosphorus dopant concentration greater than or equal to 1019/cm3;
- wherein forming the cavity comprises etching one or more oxide layers of the layer stack through the at least one vent, to thereby free the body to vibrate or deflect within the cavity, and, subsequently, plugging the at least one vent to hermetically seal the body within the cavity;
- and
- wherein the semiconductor device comprises circuitry to (1) receive a signal representing a temperature of operation and a signal representing the resonance frequency, and (2) generate, using the signal representing the temperature of operation and the signal representing the resonance frequency, a timing reference signal, wherein the timing reference signal is to have a reduced proportional variation in frequency relative to a proportional variation in the resonance frequency as a function of change in the temperature of operation of the resonator.
3 more elements
Dependencies are inferred from the claim text.