Method for making a micromechanical device by removing a sacrificial layer with multiple sequential etchants

Abstract

An etching method, such as for forming a micromechanical device, is disclosed. One embodiment of the method is for releasing a micromechanical structure, comprising, providing a substrate; providing a sacrificial layer directly or indirectly on the substrate; providing one or more micromechanical structural layers on the sacrificial layer; performing a first etch to remove a portion of the sacrificial layer, the first etch comprising providing an etchant gas and energizing the etchant gas so as to allow the etchant gas to physically, or chemically and physically, remove the portion of the sacrificial layer; performing a second etch to remove additional sacrificial material in the sacrificial layer, the second etch comprising providing a gas that chemically but not physically etches the additional sacrificial material. Another embodiment of the method is for etching a silicon material on or within a substrate, comprising: performing a first etch to remove a portion of the silicon, the first etch comprising providing an etchant gas and energizing the etchant gas so as to allow the etchant gas to physically, or chemically and physically, remove the portion of silicon; performing a second etch to remove additional silicon, the second etch comprising providing an etchant gas that chemically but not physically etches the additional silicon.

Description

CROSS-REFERENCE TO RELATED CASES [0001] This application is a divisional of Ser. No. 10 / 154,150 to Patel, et al filed May 22, 2002, the subject matter being incorporated herein by reference.BACKGROUND [0002] A wide variety of micro-electromechanical devices (MEMS) are known, including accelerometers, DC relay and RF switches, optical cross connects and optical switches, microlenses, reflectors and beam splitters, filters, oscillators and antenna system components, variable capacitors and inductors, switched banks of filters, resonant comb-drives and resonant beams, and micromirror arrays for direct view and projection displays. There are a wide variety of methods for forming MEMS devices, including a) forming micromechanical structures monolithically on the same substrate as actuation or detection circuitry, b) forming the micromechanical structures on a separate substrate and transferring the formed structures to a circuit substrate, c) forming circuitry on one substrate and formin...

AI Technical Summary

Benefits of technology

[0003] In its most simple form, the invention is directed to etching a material where a first etch removes a portion of the material and fully or partially physically removes the material, and where a subsequent etch removes additional material and removes the material chemically but not physically. The material can be a semiconductor material such

Problems solved by technology

The result of the first and second etches can also result in an undercut such as for micro

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