Methods of manufacture for MEMS switches with reduced switching voltage

• US 10,647,569 B2
• Filed: 09/27/2017
• Issued: 05/12/2020
• Est. Priority Date: 04/22/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Luce, Stephen E., Stamper, Anthony K.
• Primary Examiner(s): Tugbang, A. Dexter
• Application Number:
  US15/717,187
• Publication Number:
  US 20180016137A1
• Time in Patent Office: 958 Days
• 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 1/00166 Electrodes
• CPC Class Codes: B81C 1/00523 Etching material
• CPC Class Codes: B81C 1/00698 Electrical characteristics, e.g. by doping materials
• CPC Class Codes: B81C 2201/0132 Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
• CPC Class Codes: B81C 2201/0133 Wet etching
• CPC Class Codes: B81C 2201/0135 Controlling etch progression
• CPC Class Codes: B81C 2201/0145 Spark erosion
• CPC Class Codes: B81C 2201/0154 other processes for film patterning not provided for in B81C2201/0149 - B81C2201/015
• CPC Class Codes: B81C 2203/0145 Hermetically sealing an opening in the lid
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 1/58 Electric connections to or between contacts; Terminals for high tension switches H01H33/025; for electromagnetic relays H01H50/14; for circuit breakers H01H71/08
• CPC Class Codes: H01H 1/66 Contacts sealed in an evacuated or gas-filled envelope, e.g. magnetic dry-reed contacts
• CPC Class Codes: H01H 11/00 Apparatus or processes specially adapted for the manufacture of electric switches processes specially adapted for manufacture of rectilinearly movable switches having a plurality of operating members associated with different sets of contacts, e.g. keyboards, H01H13/88
• CPC Class Codes: H01H 2059/0018 Special provisions for avoiding charge trapping, e.g. insulation layer between actuating electrodes being permanently polarised by charge trapping so that actuating or release voltage is altered
• CPC Class Codes: H01H 49/00 Apparatus or processes specially adapted to the manufacture of relays or parts thereof
• CPC Class Codes: H01H 50/005 using micromechanics
• CPC Class Codes: H01H 59/00 Electrostatic relays; Electro-adhesion relays
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

An approach includes a method of fabricating a switch. The approach includes forming a first cantilevered electrode over a first fixed electrode, forming a second cantilevered electrode with an end that overlaps the first cantilevered electrode, forming a third cantilevered electrode operable to directly contact the first cantilevered electrode upon an application of a voltage to a second fixed electrode, and forming a hermetically sealed volume encapsulating the first fixed electrode, the second fixed electrode, the first cantilevered electrode, and the second cantilevered electrode.

Claims

1. A method of fabricating a switch comprising:

forming a first cantilevered electrode over a first fixed electrode;

forming a second cantilevered electrode with an end that overlaps the first cantilevered electrode;

forming a third cantilevered electrode operable to directly contact the first cantilever electrode upon an application of a voltage to a second fixed electrode; and

forming a hermetically sealed volume encapsulating the first fixed electrode, the second fixed electrode, the first cantilevered electrode, and the second cantilevered electrode,

wherein the forming the hermetically sealed volume comprises;

forming at least one hole in a nitride liner to gain access to a sacrificial resist;

removing the sacrificial resist; and

closing the at least one hole by deposition of additional liner material, and

wherein a material which forms the hermetically sealed volume comprises nitride.

2. The method of claim 1, wherein the hermetically sealed volume is a dome.

3. The method of claim 2, wherein the dome is oval shaped.

4. The method of claim 1, wherein overlapping portions of the first cantilevered electrode and the second cantilevered electrode are separated by a vertical distance of about two microns.

5. The method of claim 1, wherein the third cantilevered electrode is formed above the second cantilevered electrode.

6. The method of claim 1, wherein the second cantilevered electrode is formed above the first cantilevered electrode.

7. The method of claim 1, wherein the first cantilevered electrode is formed such that upon application of a negative voltage to the first fixed electrode and a positive voltage to the second cantilevered electrode, the first cantilevered electrode is operable to directly contact the third cantilevered electrode.

8. The method of claim 7, wherein the positive voltage is about 30 volts.

9. The method of claim 7, wherein the negative voltage is about −

30 volts and the positive voltage is about 30 volts.

10. The method of claim 1, further comprising forming an extending protrusion which extends upward from an upper surface of an arm of the first cantilevered electrode.

11. The method of claim 1, wherein a height of the second fixed electrode is higher than a height of the first fixed electrode.