Method of manufacture MEMS switches with reduced voltage
An approach includes a method of fabricating a switch. The approach includes forming a first fixed electrode and a second fixed electrode, forming a first cantilevered electrode aligned vertically over the first fixed electrode, forming a second cantilevered electrode aligned vertically over the first fixed electrode and which has an end that overlaps the first cantilevered electrode, forming a third cantilevered electrode aligned vertically over the second fixed electrode and operable to directly contact the first cantilevered electrode upon an application of a voltage to the 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.
1. A method of fabricating a switch comprising:
forming a first fixed electrode and a second fixed electrode;
forming a first cantilevered electrode aligned vertically over the first fixed electrode;
forming a second cantilevered electrode aligned vertically over the first fixed electrode, and which has an end that overlaps and is parallel to an end of the first cantilevered electrode;
forming a third cantilevered electrode aligned vertically over the second fixed electrode and operable to directly contact the first cantilever electrode upon an application of a positive voltage to the second fixed electrode;
forming an extending protrusion which extends upward from an upper surface of an arm of the first cantilever electrode which is positioned under the third cantilevered 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.
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 end of the first cantilevered electrode and the end of 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 negative voltage is about −30 volts and the positive voltage is about 30 volts.
9. The method of claim 1 , wherein the hermetically sealed volume comprises nitride.
10. The method of claim 1 , wherein the positive voltage is about 30 volts.
11. A method of fabricating a switch comprising:
forming a first fixed electrode and a second fixed electrode;
forming a first cantilevered electrode aligned vertically over the first fixed electrode;
forming a second cantilevered electrode aligned vertically over the first fixed electrode, and which has an end that overlaps the first cantilevered electrode;
forming a third cantilevered electrode aligned vertically over the second fixed electrode and operable to directly contact the first cantilever electrode upon an application of a voltage to the 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;
etching the sacrificial resist; and
closing the at least one hole by deposition of additional liner material.