Trilayered beam MEMS device and related methods

• US 6,746,891 B2
• Filed: 11/08/2002
• Issued: 06/08/2004
• Est. Priority Date: 11/09/2001
• Status: Expired due to Term

• Current Assignee: AAC Technologies Pte Limited (AAC Technologies Holdings Inc.)
• Original Assignee: WiSpry, Inc (AAC Technologies Holdings Inc.), Turnstone Systems, Inc.
• Inventors: Cunningham, Shawn Jay, Tatic-Lucic, Svetlana
• Primary Examiner(s): GHYKA, ALEXANDER G
• Application Number:
  US10/290,920
• Publication Number:
  US 20030119221A1
• Time in Patent Office: 578 Days
• Field of Search: 438/48, 438/52, 438/53, 257/415
• US Class Current: 438/52
• CPC Class Codes: B81B 2201/014 having a cantilever fixed on one side connected to one or more dimples
• CPC Class Codes: B81B 2201/018 Switches not provided for in B81B2201/014 - B81B2201/016
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 3/0024 Transducers for transforming thermal into mechanical energy or vice versa, e.g. thermal or bimorph actuators electric motors using thermal effects H02N10/00
• 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: B81C 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244
• CPC Class Codes: B81C 2201/0107 Sacrificial metal
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: B81C 2201/0109 Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
• CPC Class Codes: H01H 1/04 Co-operating contacts of different material
• CPC Class Codes: H01H 1/504 by thermal means
• CPC Class Codes: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 2001/0063 having electrostatic latches, i.e. the activated position is kept by electrostatic forces other than the activation force
• CPC Class Codes: H01H 2001/0089 Providing protection of elements to be released by etching of sacrificial element; Avoiding stiction problems, e.g. of movable element to substrate
• CPC Class Codes: H01H 2059/0072 with stoppers or protrusions for maintaining a gap, reducing the contact area or for preventing stiction between the movable and the fixed electrode in the attracted position
• CPC Class Codes: H01H 2061/006 Micromechanical thermal relay
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01H 61/04 wherein the thermally-sensitive member is only heated directly
• CPC Class Codes: H01L 23/3735 : Laminates or multilayers, e.g. direct bond copper ceramic substrates
• CPC Class Codes: H01L 23/522 : including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
• CPC Class Codes: H01L 27/1203 : the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H02N 1/006 : of the gap-closing type H02N1/004 takes precedence
• CPC Class Codes: H02N 10/00 : Electric motors using thermal effects motors using expansion or contraction of bodies due to heating or cooling F03G7/06
• CPC Class Codes: Y10T 29/49222 : forming array of contacts or terminals

Abstract

Trilayered Beam MEMS Device and Related Methods. According to one embodiment, a method for fabricating a trilayered beam is provided. The method can include depositing a sacrificial layer on a substrate and depositing a first conductive layer on the sacrificial layer. The method can also include forming a first conductive microstructure by removing a portion of the first conductive layer. Furthermore, the method can include depositing a structural layer on the first conductive microstructure, the sacrificial layer, and the substrate and forming a via through the structural layer to the first conductive microstructure. Still furthermore, the method can include the following: depositing a second conductive layer on the structural layer and in the via; forming a second conductive microstructure by removing a portion of the second conductive layer, wherein the second conductive microstructure electrically communicates with the first conductive microstructure through the via; and removing a sufficient amount of the sacrificial layer so as to separate the first conductive microstructure from the substrate, wherein the structural layer is supported by the substrate at a first end and is freely suspended above the substrate at an opposing second end.

Claims

1. A method for fabricating a trilayered beam, comprising:

(a) depositing a sacrificial layer on a substrate;

(b) depositing a first conductive layer on the sacrificial layer;

(c) forming a first conductive microstructure by removing a portion of the first conductive layer;

(d) depositing a structural layer on the first conductive microstructure and the sacrificial layer;

(e) forming a via through the structural layer to the first conductive microstructure;

(f) depositing a second conductive layer on the structural layer and in the via;

(g) forming a second conductive microstructure by removing a portion of the second conductive layer, wherein the second conductive microstructure electrically communicates with the first conductive microstructure through the via; and

(h) removing a sufficient amount of the sacrificial layer so as to separate the first conductive microstructure from the substrate, wherein the structural layer is supported by the substrate at a first end and is freely suspended above the substrate at an opposing second end.

2. The method of claim 1 wherein the substrate is composed of a material selected from the group consisting of silicon, silica, glass, quartz, sapphire, zinc oxide, alumina, Group III-V compounds, and alloys thereof.

3. The method of claim 1 wherein the first conductive microstructure is composed of a material selected from the group consisting of gold, nickel, iron and alloys thereof.

4. The method of claim 1 wherein the second conductive microstructure is composed of a material selected from the group consisting of gold, nickel, iron and alloys thereof.

5. The method of claim 1 wherein the structural layer is composed of a material selected from the group consisting of polysilicon, silicon nitride, silicon dioxide, silicon carbide, aluminum and alloys thereof.

6. The method of claim 1 wherein the first conductive microstructure and the second conductive microstructure have substantially the same shape and dimensions.

7. A method for fabricating an actuator having a trilayered beam, comprising:

(a) forming a first electrode on a substrate;

(b) depositing a sacrificial layer on the first electrode and the substrate;

(c) forming a second electrode on the sacrificial layer;

(d) depositing a structural layer on the second electrode and the sacrificial layer;

(e) forming a via through the structural layer to the second electrode;

(f) depositing a conductive layer on the structural layer and in the via;

(g) forming a conductive microstructure by removing a portion of the conductive layer, wherein the conductive microstructure electrically communicates with the second electrode through the via; and

(h) removing a sufficient amount of the sacrificial layer so as to separate the second electrode from the substrate, wherein the structural layer is supported by the substrate at a first end and is freely suspended above the substrate at an opposing second end.

8. The method of claim 7 wherein the substrate is composed of a material selected from the group consisting of silicon, silica, glass, quartz, sapphire, zinc oxide, alumina, Group III-V compounds, and alloys thereof.

9. The method of claim 7 wherein the first electrode is composed of a material selected from the group consisting of gold, nickel, iron and alloys thereof.

10. The method of claim 7 wherein the second electrode is composed of a material selected from the group consisting of gold, nickel, iron and alloys thereof.

11. The method of claim 7 wherein the first and second electrodes have substantially the same shape and dimensions.

12. The method of claim 7 further including providing a voltage source having an electrical connection across the first electrode and the conductive microstructure.

13. The method of claim 7 further including providing a first contact attached to the structural layer and a second contact attached to the substrate for contacting when a voltage is applied across the first electrode and the conductive microstructure.

14. The method of claim 7 wherein the first electrode is formed from a layer of conductive material deposited on the substrate.

15. The method of claim 7 wherein the second electrode is formed from a layer of conductive material deposited on the sacrificial layer.

16. A method for fabricating a microscale switch having a trilayered beam, comprising:

(a) forming a first electrode on a substrate;

(b) forming a first contact on the substrate;

(c) depositing a sacrificial layer on the first electrode, the first contact, and the substrate;

(d) forming a second electrode on the sacrificial layer;

(e) forming a second contact on the sacrificial layer;

(f) depositing a structural layer on the second electrode, the second contact, and the sacrificial layer;

(g) forming a first conductive, interconnect via through the structural layer to the second electrode;

(h) forming a second conductive, interconnect via through the structural layer to the second contact;

(i) forming an electrode interconnect on the structural layer that contacts the first interconnect via; and

(j) forming a contact interconnect on the structural layer that contacts the second interconnect via.

17. The method of claim 16 wherein the electrode interconnect and the second electrode have substantially the same shape and dimensions.

18. The method of claim 16 wherein the contact interconnect and the second contact have substantially the same shape and dimensions.

19. A method for fabricating a microscale switch having a cross-bar interconnect, comprising:

(a) forming a conductive interconnect on a substrate;

(b) depositing dielectric layer on the conductive interconnect;

(c) forming a first conductive, interconnect via through the dielectric layer to the conductive interconnect;

(d) forming a first contact on the dielectric layer wherein the first contact connects to the first interconnect via;

(e) forming a first electrode on the substrate;

(f) depositing a sacrificial layer on the first electrode, the first contact, and the substrate;

(g) forming a second electrode on the sacrificial layer;

(h) forming a second contact on the sacrificial layer;

(i) depositing a structural layer on the second electrode, the second contact, and the sacrificial layer;

(j) forming a second conductive, interconnect via through the structural layer to the second electrode;

(k) forming a third conductive, interconnect via through the structural layer to the second contact;

(l) forming an electrode interconnect on the structural layer that contacts the second interconnect via; and

(m) forming a contact interconnect on the structural layer that contacts the third interconnect via.

20. A method for fabricating a microscale switch having a trilayered beam, comprising:

(a) forming a first and second conductive interconnect on a substrate;

(b) depositing at least one dielectric layer on the first and second conductive interconnect;

(c) forming a first and second conductive, interconnect via through the at least one dielectric layer to the first and second conductive interconnects, respectively;

(d) forming a first and second contact on the dielectric layer wherein the first contact connects to the first interconnect via and the second contact connects to the second interconnect via;

(e) forming a first electrode on the substrate;

(f) depositing a sacrificial layer on the first electrode, the first contact, and the second contact;

(g) forming a second electrode on the sacrificial layer;

(h) forming a third and fourth contact on the sacrificial layer;

(i) depositing a structural layer on the second electrode, the third contact, the fourth contact, and the sacrificial layer;

(j) forming a third conductive, interconnect via through the structural layer to the second electrode;

(k) forming a fourth and fifth conductive, interconnect via through the structural layer to the third and fourth contacts, respectively;

(l) forming an electrode interconnect on the structural layer that contacts the third interconnect via; and

(m) forming a contact interconnect on the structural layer that contacts the fourth and fifth interconnect vias.

21. A method of implementing switching function in a switch having conductive interconnects, the method comprising:

(a) providing a switch having conductive interconnects, the switch comprising;

(i) a substrate having a first and second conductive interconnect and a stationary electrode;

(ii) first and second dielectric layers formed on the first and second conductive interconnects, respectively;

(iii) first and second stationary contacts attached to the first and second dielectric layers, respectively, and having electrical communication with the first and second conductive interconnects, respectively;

(iv) a movable structural layer including a bottom surface suspended over the first and second stationary contacts and a top surface opposing the bottom surface;

(v) a movable electrode attached to the bottom surface of the structural layer whereby the movable electrode is separated from the stationary electrode by a gap;

(vi) an electrode interconnect attached to the top surface of the structural layer and connected to the movable electrode for electrical communication; and

(vii) a movable contact attached to the bottom surface of the structural layer and positioned to contact the first and second stationary contacts when the structural layer moves towards the first and second stationary contacts; and

(b) applying a voltage between the electrode interconnect and the stationary electrode to electrostatically couple the movable electrode with the stationary electrode across the gap, whereby the resilient structural layer is deflected toward the substrate and the movable contact contacts the first and stationary contacts for establishing electrical communication between the first and second conductive interconnects.