METHOD AND APPARATUS FOR MANUFACTURING A RESONATING STRUCTURE

• US 20110273061A1
• Filed: 07/19/2011
• Published: 11/10/2011
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Sand9, Inc.
• Inventors: THALMAYR, FLORIAN, Kuypers, Jan H., Schoepf, Klaus Juergen
• Granted Patent: US 8,689,426 B2
• Time in Patent Office: Days
• US Class Current: 310/346
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: H01F 3/04 made from strips or ribbons
• CPC Class Codes: H03H 2009/241 Bulk-mode MEMS resonators
• CPC Class Codes: H03H 9/02102 of temperature influence cutting angles H03H9/02015
• CPC Class Codes: H03H 9/02228 Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
• CPC Class Codes: H03H 9/02244 of microelectro-mechanical resonators
• CPC Class Codes: H03H 9/02275 Comb electrodes
• CPC Class Codes: H03H 9/02448 of temperature influence
• CPC Class Codes: H03H 9/02535 of surface acoustic wave devices
• CPC Class Codes: H03H 9/02574 of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
• CPC Class Codes: H03H 9/02834 of temperature influence cut angles H03H9/02543
• CPC Class Codes: H03H 9/02984 Protection measures against damaging
• CPC Class Codes: H03H 9/02992 Details of bus bars, contact pads or other electrical connections for finger electrodes
• CPC Class Codes: H03H 9/2405 of microelectro-mechanical resonators
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005
• CPC Class Codes: H04R 2217/00 Details of magnetostrictive, piezoelectric, or electrostrictive transducers covered by H04R15/00 or H04R17/00 but not provided for in any of their subgroups
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: H10N 30/04 Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/80 : Constructional details
• CPC Class Codes: Y10T 29/42 : Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 : Acoustic transducer
• CPC Class Codes: Y10T 29/4908 : Acoustic transducer

Abstract

Mechanical resonating structures are described, as well as related devices and methods. The mechanical resonating structures may have a compensating structure for compensating environmental changes.

Claims

1. A method, comprising:

constructing a mechanical resonating structure by applying an active layer on a surface of a compensating structure, wherein the compensating structure comprises;

a first layer having a stiffness that adapts to a change in temperature over a first temperature range;

a third layer having a stiffness that adapts to a change in temperature over a second temperature range; and

a second layer between the first layer and the third layer; and

adjusting an operational profile of the mechanical resonating structure by adding one or more materials to at least a first portion of the mechanical resonating structure, removing one or more materials from at least a second portion of the mechanical resonating structure, or combinations thereof.

2. The method of claim 1, wherein the operational profile comprises a measurement of at least one of a resonant frequency of the mechanical resonating structure, a profile of a temperature coefficient of frequency of the mechanical resonating structure, one or more temperatures for which temperature coefficient of frequency of the mechanical resonating structure is approximately zero, and a temperature coefficient of stiffness of the mechanical resonating structure.

3. The method of claim 1, wherein the first and second temperature ranges are substantially similar.

4. The method of claim 1, wherein a thicknesses of each of the active layer, the first layer, the second layer, and the third layer results in a plurality of thickness ratios therebetween, and wherein the operational profile is influenced by at least one of the plurality of thickness ratios.

5. The method of claim 4, wherein adjusting the operational profile of the mechanical resonating structure comprises adjusting at least one of the plurality of thickness ratios by adding one or more materials to at least one of the active layer, the first layer, the second layer, and the third layer, removing one or more materials from at least one of the active layer, the first layer, the second layer, and the third layer, or combinations thereof.

6. The method of claim 1, comprising:

forming an adjustment layer on the first and second portions of the mechanical resonating structure; and

adjusting the operational profile of the mechanical resonating structure by adding one or more materials to the adjustment layer, removing one or more materials from the adjustment layer, or combinations thereof.

7. The method of claim 1, wherein at least one of the first and second portions of the mechanical resonating structure correspond to an adjustment surface, and wherein the adjustment surface is located on at least one of a top surface of the mechanical resonating structure, a side surface of the mechanical resonating structure, a bottom surface of the mechanical resonating structure, or combinations thereof.

8. The method of claim 6, wherein the adjustment layer is formed of a conductive material, a non-conductive material, or a combination thereof.

9. The method of claim 1, comprising adding the one or more materials to the first portion of the mechanical resonating structure according to a deposition process.

10. The method of claim 9, wherein the deposition process comprises at least one of a vapor deposition process, a sputter deposition process, a thin film deposition process, an electron beam-induced deposition process, and an ion beam-induced deposition process.

11. The method of claim 1, comprising removing the one or more materials from the second portion of the mechanical resonating structure according to a removal process comprising at least one of an electron beam process, an ion beam process, a chemical process, a laser induced removal process, a heat induced removal process, and a photolithography process.

12. The method of claim 1, comprising:

measuring the operational profile of the mechanical resonating structure; and

determining at least one divergent property between the measured operational profile and a desired operational profile; and

adjusting the operational profile according to the at least one divergent property.

13. The method of claim 12, wherein the mechanical resonating structure is constructed on a wafer with a plurality of other mechanical resonating structures, and wherein the method comprises:

measuring the operational profile of at least one of the plurality of other mechanical resonating structures;

determining an approximation of a measure of the operational profile of the plurality of other mechanical resonating structures from a statistical analysis of at least one of the measured operational profile of the mechanical resonating structure, the measured operational profile of the at least one other mechanical resonating structure, and a history of measured operational profiles of mechanical resonating structures on other wafers; and

adjust the operational profile of at least a portion of the mechanical resonating structures constructed on the wafer according to the approximation.

14. The method of claim 13, comprising performing a coarse tune adjustment of the operational profile of the portion of the mechanical resonating structures on the wafer according to the approximation.

15. The method of claim 13, comprising performing a fine tune adjustment of the operational profile of the portion of the mechanical resonating structures constructed on the wafer according to the approximation.

16. The method of claim 1, comprising adjusting the operational profile of the mechanical resonating structure prior to or after removing the mechanical resonating structure from a wafer from which the mechanical resonating structure was constructed.

17. The method of claim 1, comprising:

stimulating the mechanical resonating structure;

receiving a signal from the mechanical resonating structure responsive to the stimulation;

measuring the operational profile of the mechanical resonating structure from the signal;

comparing the measured operational profile to a desired operational profile;

identifying from the comparison at least one divergent property between the measured operational profile and the desired operational profile; and

adjusting the operational profile of the mechanical resonating structure according to the at least one divergent property.

18. The method of claim 17, wherein the mechanical resonating structure is stimulated by an electrical stimulation, an electro-mechanical stimulation, a mechanical stimulation, photonically induced stimulation, thermally induced stimulation, magnetically induced stimulation, or combinations thereof.

19. The method of claim 17, comprising controlling an environment of the mechanical resonating structure while measuring the operational profile of the mechanical resonating structure, wherein the controlled environment controls at least one of temperature, humidity, pressure, contaminants, and combinations thereof, and wherein the operational profile is measured before, during or after the operational profile is adjusted.

20. The method of claim 1, wherein the active material is a piezoelectric material, and wherein the first and second layers are formed of silicon dioxide, and wherein the second layer is formed of one of silicon, silicon carbide, sapphire, quartz, germanium, gallium arsenide, aluminum nitride, and diamond.

21. A method, comprising:

obtaining a mechanical resonating structure comprising a compensating structure, wherein the compensating structure comprises one or more materials having an adaptive stiffness that reduces a variance in a resonating frequency of the mechanical resonating structure (f0); and

adjusting at least one of a value of f0 of the obtained mechanical resonating structure and a value of a temperature for which temperature coefficient of frequency of the obtained mechanical resonating structure is approximately zero (T0) by altering a thickness of at least one targetable material of the mechanical resonating structure.

22. The method of claim 21, wherein the at least one targetable material comprises a first portion of a first material having a first thickness and a second portion of a second material having a second thickness, wherein the first and second materials differ, wherein the obtained mechanical resonating structure is constructed according to a desired ratio of a first surface area of the first portion and a second surface area of the second portion to enable selective adjustment of at least one of the value of f0 and the value of T0, and wherein the method comprises:

detecting that at least one of the value of f0, the value of T0, and a thickness of at least one material layer of the mechanical resonating structure is offset from desired values for f0, T0 and material layer thicknesses of the mechanical resonating structure; and

adjusting according to the detected offset at least one of the value of f0 and the value of T0 to approximate at least one of the desired values of f0 and T0 by altering at least one of the first thickness of at least a portion of the first material and the second thickness of at least a portion of the second material.

23. The method of claim 21, wherein the at least one targetable material comprises a first material, wherein the obtained mechanical resonating structure is constructed so that a first ratio of sensitivity to a change in the value of f0 and the value of T0 as a function of thickness in the first material is similar to a second ratio of sensitivity to a change in the value of f0 and the value of T0 as a function of thickness in a second material of the obtained mechanical resonating structure, and wherein the method comprises:

detecting that at least one of the value of f0, the value of T0, and a thickness of at least one material layer of the mechanical resonating structure is offset from desired values for f0, T0 and material layer thicknesses of the mechanical resonating structure; and

adjusting according to the detected offset the values of f0 and T0 to approximate the desired values of f0 and T0 by altering the thickness of at least a portion of the first material.

24. The method of claim 21, wherein the mechanical resonating structure is constructed with a conductor configuration that causes a resonance mode of operation of the mechanical resonating structure to be influenced more by a lateral displacement of the mechanical resonating structure than by a displacement in thickness of the mechanical resonating structure.

25. The method of claim 24, wherein the conductor configuration comprises an interdigital transducer electrode configuration.

26. The method of claim 21, wherein a first party that adjusts at least one of the value of f0 and the value of T0 is affiliated with a second party that constructs the mechanical resonating structure.

27. A mechanical resonator, comprising:

a conductor;

an active layer coupled to conductor on a first surface; and

a compensating structure coupled to a second surface of the active layer;

wherein the compensating structure comprises one or more materials having an adaptive resistance to deform that reduces a variance in a resonating frequency of the mechanical resonating structure (f0);

wherein at least the conductor, the active layer and the compensating structure form a mechanical resonating structure having a plurality of layers of materials;

wherein a thickness of each of the plurality of layers of materials results in a plurality of thickness ratios therebetween;

wherein the mechanical resonating structure is constructed with target ranges for the plurality thickness ratios to enable selective tuning of a value of f0 and a value of a temperature for which temperature coefficient of frequency of the mechanical resonating structure is approximately zero (T0) by altering a thickness of at least one targetable material of the mechanical resonating structure.

28. The mechanical resonator of claim 27, wherein a configuration of the conductor causes a resonance mode of operation of the mechanical resonating structure to be influenced more by a lateral displacement of the plurality of layers of materials of the mechanical resonating structure than by a thickness displacement of the plurality of layers of materials of the mechanical resonating structure.

29. The mechanical resonator of claim 27, wherein the at least one targetable material comprises a first portion of the conductor having a first thickness and a second portion of the active layer having a second thickness, wherein the conductor and the active layer have material properties that differ, wherein the mechanical resonating structure is constructed according to a desired ratio of a first surface area of the first portion and a second surface area of the second portion to enable selective tuning of the value of f0 and the value of T0 by adjusting a thickness of at least one of a portion of the conductor and the active layer.

30. The mechanical resonator of claim 27, wherein the at least one targetable material comprises a first material of the mechanical resonating structure, wherein the mechanical resonating structure is constructed so that a first ratio of sensitivity to a change in the value of f0 and the value of T0 as a function of thickness in the first material is similar to a second ratio of sensitivity to a change in the value of f0 and the value of T0 as a function of thickness in a second material of the mechanical resonating structure to enable tuning of the value of f0 and the value of T0 by adjusting a thickness of at least a portion of the first material.

31. The mechanical resonator of claim 30, wherein the compensating structure comprises first, second and third layers, wherein the second layer is formed between the first and second layers, wherein the first and third layers are formed with silicon dioxide material, wherein the second layer is formed with silicon material, wherein the first material comprises the silicon dioxide material of the first layer or the second layer, and wherein second material comprises the silicon material of the second layer.

32. The mechanical resonator of claim 28, wherein the mechanical resonating structure comprises a second conductor between the active layer and the compensating structure.

33. The mechanical resonator of claim 28, wherein the mechanical resonator operates as one of a resonator, an accelerometer, a gyroscope, and a filter, and wherein the mechanical resonator operates in a computing device.