Method for making micromechanical switch
AssigneeBritish Telecommunications public limited company
InventorsAnthony D. Welbourn, Judith C. McLaughlin
Life of this patent
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Abstract
A micromechanical switch is formed using a first sacrificial layer formed on a substrate. A second sacrificial layer is then formed as an island on the first sacrificial layer. A switch element layer of resilient material is then formed on the second sacrificial layer, and the outline of a switch element is defined on the switch element layer. The outline of a window is then defined, and the second sacrificial layer is etched through the window using an etchant which laterally undercuts that portion of the switch element layer which is to form the switch element. The first sacrificial layer is then etched through the window defined by the etched second sacrificial layer to define a cavity beneath said portion, thereby defining the switch element.
Claims29
A method of making a micromechanical switch, the method comprising the steps of:
- a) forming a first sacrificial layer on a substrate;
- b) forming a second sacrificial layer as an island on the first sacrificial layer;
- c) forming a switch element layer of resilient material on the second sacrificial layer;
- d) defining the outline of a switch element on the switch element layer;
- e) defining the outline of a window;
- f) etching an aperture in the second sacrificial layer through the window using an etchant which laterally undercuts that portion of the switch element layer which is to form the switch element;
- and
- g) etching the first sacrificial layer through the aperture in the etched second sacrificial layer to define a cavity beneath said portion.
A method of forming an operating cavity under a mechanically movable beam in a micromechanical switch, said method comprising the steps of:
- etching an aperture in a first sacrificial layer under said beam to expose a second sacrificial layer thereby defining the lateral extent of said cavity;
- and
- etching said second sacrificial layer through said aperture to define the depth of said cavity.
Dependencies are inferred from the claim text.