Microelectromechanical system and method

• US 8,994,126 B2
• Filed: 03/15/2013
• Issued: 03/31/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Audio Pixels Ltd. (Audio Pixels Holdings Ltd.)
• Original Assignee: Audio Pixels Ltd. (Audio Pixels Holdings Ltd.)
• Inventors: Cohen, Yuval, Kaplan, Shay
• Primary Examiner(s): Jahan, Bilkis
• Application Number:
  US13/834,026
• Publication Number:
  US 20140264646A1
• Time in Patent Office: 746 Days
• Field of Search: 257/415
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B81C 1/00134 comprising flexible or deformable structures manufacture of MEMS devices for specific applications, see relevant places, e.g. gyroscopes G01C19/5719, pressure sensors G01L9/0042, accelerometers G01P15/0802, acoustic transducers or diaphragms therefor H04R31/00

Abstract

A microelectromechanical system, including a first element and a second element, the first element having a first conductive surface facing a second conductive surface of the second element; wherein at least one of the first element and the second element is operable to constrainedly move nearer and farther from the other element; and at least one insulating separating member which is operable to mechanically maintain a separation between the first surface and the second surface, wherein a minimal distance between a first projection of a first contact area of the insulating separating member and a second projection of a second contact area of the insulating separating member is larger than a minimal separation maintained by the insulating separating member between the first element and the second element.

Claims

1. A microelectromechanical system, comprising:

a first element and a second element, the first element having a first conductive surface facing a second conductive surface of the second element;

wherein at least one of the first element and the second element is operable to constrainedly move nearer and farther from the other element; and

at least one insulating separating member which is operable to mechanically maintain a separation between the first surface and the second surface, wherein;

the insulating separating member comprises a first contact area which couples with the first surface and a second contact area which contacts with the second surface at least when the first element and the second element are nearest to one another;

wherein the first contact area defines a first projection which is a projection of a circumference of the first contact area on a reference plane which is substantially parallel to at least one of the first surface and the second surface, and the second contact area defines a second projection which is a projection of a circumference of the second contact area on the reference plane;

wherein a minimal distance between the first projection and the second projection is larger than a minimal separation maintained by the insulating separating member between the first element and the second element.

2. The microelectromechanical system of claim 1, wherein along at least a portion of the circumference of the first contact area there is a notch between the insulating separating member and the first surface in which prevails an internal electric field whose intensity is at least two times larger than an intensity of an external electric field adjacent to the notch;

wherein the minimal distance keeps the internal electric field below an electrical breakdown voltage of a medium which is included in the notch.

3. The microelectromechanical system of claim 1, wherein the first element is a planar member, wherein the second element is a moving member which is operable to constrainedly move nearer and farther from the planar member in response to a controlled temporal sequence of potential differences between the planar member and the moving member;

wherein the controlled temporal sequence of potential differences is controlled by an external controller in response to a signal inputted to the controller.

4. The microelectromechanical system of claim 1, wherein the insulating separating member comprises a first separator part whose convex envelope is substantially prismatic, and a second separator part whose convex envelope is substantially prismatic, the first separator part and the second separator part combinedly comprising at least 85% of a totality of insulating solid matter of the separating member;

wherein for each direction parallel to the reference plane, a first length is defined as a largest length of a cross section of the first separator part along the direction, and a second length is defined as a largest length of a cross section of the second separator part along the direction;

wherein the larger of the first length and the second length is larger than the minimal separation maintained by the insulating separating member between the first element and the second element.

5. The microelectromechanical system of claim 1, wherein the insulating separating member is a unified separating member which comprises the first contact area and the second contact area;

wherein the second contact area is operable to be separated from the second surface as a result of a relative movement of the second element farther from the first element.

6. The microelectromechanical system of claim 1, wherein the insulating separating member comprises:

a first separator section which comprises the first contact area, and a second separator section which comprises the second contact area which couples the second separator section to the second surface;

wherein the second separator section is operable to be separated from the first separator section as a result of a relative movement of the second element farther from the first element.

7. The microelectromechanical system of claim 6, wherein a hardness of the insulating separating member is larger than a hardness of the first element and of the second element, thereby serving as wear protection for the second element.

8. The microelectromechanical system of claim 6, wherein the first separator section is at least partially comprised in a recess in the first element so that no part of the first separator section extends outside the recess to a height which is larger than a third of a total height of the first separator section.

9. The microelectromechanical system of claim 8, wherein the first separator section is larger than the first separator section.

10. The microelectromechanical system of claim 1, comprising a separating member which comprises the insulating separating member and a part of the first element which extends from a surface plane of the first element towards the second conductive surface.

11. A microelectromechanical system, comprising:

a first element and a second element, the first element having a first conductive surface facing a second conductive surface of the second element;

wherein at least one of the first element and the second element is operable to constrainedly move nearer and farther from the other element; and

at least one insulating separating member which is operable to mechanically maintain a separation between the first surface and the second surface, wherein;

the insulating separating member comprises a first contact area which couples with the first surface and a second contact area which contacts with the second surface at least when the first element and the second element are nearest to one another;

wherein the first contact area defines a first projection which is a projection of a circumference of the first contact area on a reference plane which is substantially parallel to at least one of the first surface and the second surface, and the second contact area defines a second projection which is a projection of a circumference of the second contact area on the reference plane;

wherein a minimal distance between the first projection and the second projection is larger than 0.2 μ

m.

12. The microelectromechanical system of claim 11, wherein the insulating separating member comprises:

a first separator section which comprises the first contact area, and a second separator section which comprises the second contact area which couples the second part of the insulating separating member to the second surface;

wherein the second separator section is operable to be separated from the first separator section as a result of a relative movement of the second element farther from the first element.

13. The microelectromechanical system of claim 12, wherein the first separator section is at least partially comprised in a recess in the first element so that no part of the first separator section extends outside the recess to a height which is larger than a third of a total height of the first separator section.

14. A microelectromechanical system, comprising:

a first element and a second element, the first element having a first conductive surface facing a second conductive surface of the second element;

wherein at least one of the first element and the second element is operable to constrainedly move nearer and farther from the other element; and

at least one insulating separating member which is operable to mechanically maintain a separation between the first surface and the second surface, wherein;

the insulating separating member comprises a first contact area which couples with the first surface and a second contact area which contacts with the second surface at least when the first element and the second element are nearest to one another;

wherein the first contact area defines a first projection which is a projection of a circumference of the first contact area on a reference plane which is substantially parallel to at least one of the first surface and the second surface, and the second contact area defines a second projection which is a projection of a circumference of the second contact area on the reference plane;

wherein a minimal distance between the first projection and the second projection is larger than a manufacturing accuracy of the separating member.

15. The microelectromechanical system according to claim 14, wherein the microelectromechanical system is fabricated as one out of a plurality of similar microelectromechanical systems on a batch of one or more wafers, each of the plurality of the similar microelectromechanical systems having an insulating separating member in a similar location with respect to the respective microelectromechanical system, the insulating separating member comprising a second contact area having a largest dimension;

wherein the manufacturing accuracy is defined as a smallest threshold which is larger than 95% of the largest dimensions of the second contact areas.

16. The microelectromechanical system of claim 14, wherein the insulating separating member comprises:

a first separator section which comprises the first contact area, and a second separator section which comprises the second contact area which couples the second part of the insulating separating member to the second surface;

wherein the second separator section is operable to be separated from the first separator section as a result of a relative movement of the second element farther from the first element.

17. A method for fabrication of a microelectromechanical system, the method comprising:

obtaining a semiconductor substrate; and

deposing a plurality of material layers onto the substrate, thereby generating the microelectromechanical system which comprises a first element and a second element, the first element having a first conductive surface facing a second conductive surface of the second element;

wherein at least one of the first element and the second element is operable to constrainedly move nearer and farther from the other element; and

at least one insulating separating member which is operable to mechanically maintain a separation between the first surface and the second surface;

wherein the insulating separating member comprises a first contact area which couples with the first surface and a second contact area which contacts with the second surface at least when the first element and the second element are nearest to one another;

wherein the first contact area defines a first projection which is a projection of a circumference of the first contact area on a reference plane which is substantially parallel to at least one of the first surface and the second surface, and the second contact area defines a second projection which is a projection of a circumference of the second contact area on the reference plane;

wherein a minimal distance between the first projection and the second projection is larger than a minimal separation maintained by the insulating separating member between the first element and the second element.

18. The method according to claim 17, wherein the deposing is based on computer-assisted design (CAD) data, wherein the deposing is preceded by generating at least a part of the CAD data, wherein the generating comprises estimating an estimated runtime electrical field in a vicinity of the separating member, and computing design dimensions of the insulating separating member in response to the estimated runtime electrical field and to an estimated electrical breakdown voltage in the vicinity of the separating member.

19. The method according to claim 18, wherein the computing comprises:

based on design data for the first element and for the second element, determining minimal required distance along a design reference plane between projections of a first designed contact area and of a second designed contact area in response to the estimated electrical breakdown voltage in the vicinity of the separating member;

so that the estimated runtime electrical field would be smaller than the estimated electrical breakdown voltage;

obtaining manufacturing accuracy estimation for the fabrication of the microelectromechanical system,

determining a minimal post-manufacturing distance in response to the minimal required distance and to the manufacturing accuracy estimation; and

computing design dimensions for the first contact area and for the first contact area based on the minimal post-manufacturing distance.