Micromechanical device, micromechanical system, apparatus for adjusting sensitivity of a micromechanical device, method for producing a micromechanical device

• US 7,679,152 B2
• Filed: 04/21/2008
• Issued: 03/16/2010
• Est. Priority Date: 05/10/2007
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Graβhoff, Thomas, Klose, Thomas
• Primary Examiner(s): Dickey; Thomas L
• Assistant Examiner(s): YUSHIN, NIKOLAY K
• Application Number:
  US12/106,417
• Publication Number:
  US 20080278785A1
• Time in Patent Office: 694 Days
• Field of Search: 257/415, 257/414, 257/E21.001, 438/48, 438/50, 438/622, 359/213, 359/237, 359/213.1, 267/273, 333/186, 333/219, 310/309, 335/78, 381/174, 735/041.2
• US Class Current: 257/415
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B

Abstract

A micromechanical device has a layer; at least a first slot formed in the layer to define a first oscillation element oscillatably suspended via a first spring portion of the layer; and at least a second slot formed in the layer to define a second oscillation element oscillatably suspended via a second spring portion of the layer, wherein a trench is formed in the spring portion pair in a main surface of the layer, wherein a resonance frequency of the first oscillation element is different from that of the second oscillation element, and the first and second spring portions and the trench are formed such that, in an anisotropic lateral material removal and/or addition of the first and second spring portions, a ratio of a relative change of the resonance frequency of the second oscillation element to that of the first oscillation element ranges from 0.8 to 1.2.

Claims

1. A micromechanical device comprising:

a layer;

at least a first slot formed in the layer to define a first oscillation element oscillatably suspended via a first spring portion of the layer; and

at least a second slot formed in the layer to define a second oscillation element oscillatably suspended via a second spring portion of the layer, wherein a trench is formed in the second spring portion in a main surface of the layer,

wherein a resonance frequency of the first oscillation element is different from a resonance frequency of the second oscillation element, and the first spring portion,

the second spring portion and the trench are formed such that, in an anisotropic lateral material removal and/or an anisotropic lateral material addition of the first spring portion and the second spring portion, a ratio of a relative change of the resonance frequency of the second oscillation element to a relative change of the resonance frequency of the first oscillation element ranges from 0.8 to 1.2.

2. The micromechanical device according to claim 1, wherein the resonance frequency of the first oscillation element is smaller than the resonance frequency of the second oscillation element.

3. The micromechanical device according to claim 1, wherein a ratio of the resonance frequency of the second oscillation element to the resonance frequency of the first oscillation element lies outside a range from 0.5 to 2.

4. The micromechanical device according to claim 1, wherein a ratio of the resonance frequency of the second oscillation element to the resonance frequency of the first oscillation element lies outside a range from 0.8 to 1.2, and the ratio of the relative change of the resonance frequency of the second oscillation element to a relative change of the resonance frequency of the second oscillation element to a relative change of the resonance frequency of the first oscillation element ranges from 0.9 to 1.1.

5. The micromechanical device according to claim 1, wherein the trench comprises a straight, curved or meander-shaped structuring.

6. The micromechanical device according to claim 1, wherein the trench is formed at least partially continuously from the main surface to a second main surface opposite the main surface.

7. The micromechanical device according to claim 1, wherein a multiplicity of trenches is formed in the spring portion in the main surface of the layer.

8. The micromechanical device according to claim 7, wherein at least part of the multiplicity of trenches is arranged in parallel with respect to each other.

9. The micromechanical device according to claim 8, wherein at least part of the multiplicity of trenches is arranged behind each other in a line.

10. The micromechanical device according to claim 1, wherein a further slot is formed in the layer next to the second slot, in order to define, together with the second slot, a further spring portion arranged opposite to the second spring portion and the oscillation element of the layer, wherein the oscillation element is oscillatably suspended via the second and the further spring portion, and a further trench is formed in the further spring portion in the main surface of the layer.

11. The micromechanical device according to claim 10, wherein the trench and the further trench are arranged symmetrically to a central axis of the oscillation element, wherein the central axis is orthogonal to a central axis of the oscillation element defined by the trenches.

18. The micromechanical device according to claim 1, wherein the trench is formed in the form of a depression in the spring portion in the main surface of the layer.

19. The micromechanical device according to claim 1, wherein the trench is formed in the spring portion in the main surface of the layer, and wherein the trench is shorter than a length of the spring portion.

20. The micromechanical device according to claim 1, wherein the first spring portion, the second spring portion and the trench are formed such that, in the anisotropic lateral material removal and/or the anisotropic lateral material addition of the first spring portion and the second spring portion, the ratio of the relative change of the resonance frequency of the second oscillation element to the relative change of the resonance frequency of the first oscillation element ranges from 0.8 to 1.2 in case the anisotropic lateral material removal and/or the anisotropic lateral material addition is the same for all spring portions, both in magnitude and in sign.

12. A micromechanical device comprising a layer, in which at least two outer slots are formed to define a first oscillation system with an oscillating frame oscillatably suspended via a first outer spring portion and a second outer spring portion of the layer, and wherein at least two inner slots are formed in the layer within the oscillating frame, in order to define a second oscillation system with an oscillation element oscillatably suspended via two inner spring portions of the layer, wherein a resonance frequency of the first oscillation system is different from a resonance frequency of the second oscillation system, wherein a trench each is formed in a main surface of the layer in a pair of the spring portions, and wherein the inner spring portions, the outer spring portions and the trenches are formed such that, in an anisotropic lateral material removal and/or an anisotropic lateral material addition of the inner spring portions and the outer spring portions, a ratio of a relative change of the resonance frequency of the second oscillation system to a relative change of the resonance frequency of the first oscillation system ranges from 0.8 to 1.2.

13. The micromechanical device according to claim 12, wherein the resonance frequency of the first oscillation system is smaller than the resonance frequency of the second oscillation system, and the trenches are formed in the inner spring portions.

14. The micromechanical device according to claim 12, wherein the two inner spring portions lie on a first central axis of the oscillation element, and the two outer spring portions are arranged on a second central axis of the oscillation element, which is orthogonal to the first central axis.

15. A micromechanical system, comprising

a first micromechanical device comprising

a layer in which at least one slot is formed to define an oscillation element oscillatably suspended via a spring portion of the layer;

and

a second micromechanical device comprising

a layer in which at least a second slot is formed to define a second oscillation element oscillatably suspended via a second spring portion of the layer, wherein a trench is formed in a main surface of the layer in the second spring portion;

wherein a resonance frequency of the first oscillation element is different from a resonance frequency of the second oscillation element, and the first spring portion, the second spring portion and the trench are formed such that, in an anisotropic lateral material removal and/or an anisotropic lateral material addition of the first spring portion and the second spring portion, a ratio of a relative change of the resonance frequency of the second oscillation element to a relative change of the resonance frequency of the first oscillation element ranges from 0.8 to 1.2.

16. The micromechanical system according to claim 15, wherein the resonance frequency of the first oscillation element is smaller than the resonance frequency of the second oscillation element.

17. The micromechanical system according to claim 15, wherein, in the second micromechanical device, a further slot is formed in the layer apart from the second slot, in order to define, together with the second slot, a further spring portion arranged opposite to the second spring portion and the oscillation element, wherein the oscillation element is oscillatably suspended via the two spring portions, and a further trench is formed in the main surface of the layer in the further spring portion.

21. A method for producing a micromechanical device comprising:

providing a layer;

producing at least a first slot in the layer to define an oscillation element oscillatably suspended via a spring portion of the layer; and

producing at least a second slot in the layer to define an oscillation element oscillatably suspended via a spring portion of the layer; and

forming a trench in the second spring portion in a main surface of the layer,

wherein a resonance frequency of the first oscillation element is different from a resonance frequency of the second oscillation element, and the first spring portion, the second spring portion and the trench are formed such that, in an anisotropic lateral material removal and/or an anisotropic lateral material addition of the first spring portion and the second spring portion, a ratio of a relative change of the resonance frequency of the second oscillation element to a relative change of the resonance frequency of the first oscillation element ranges from 0.8 to 1.2.

22. The method according to claim 21, wherein the resonance frequency of the first oscillation element is smaller than a resonance frequency of the second oscillation element.

23. The method for producing according to claim 21, wherein producing the at least one first slot, producing the at least one second slot, and forming the trench in the at least second spring portion take place in one fabrication step.

24. The method for producing according to claim 21, wherein the fabrication conditions are the same at least when producing the at least one first slot, producing the at least one second slot, and forming the trench in the at least second spring portion.