Method for release of surface micromachined structures in an epitaxial reactor

• US 7,595,539 B2
• Filed: 06/16/2005
• Issued: 09/29/2009
• Est. Priority Date: 12/30/2002
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus
• Primary Examiner(s): Weiss; Howard
• Assistant Examiner(s): RAO, SHRINIVAS H
• Application Number:
  US11/155,035
• Publication Number:
  US 20070178703A1
• Time in Patent Office: 1,566 Days
• Field of Search: 257/E33.005, 257/E21.102, 216/2, 735/04
• US Class Current: 257/415
• CPC Class Codes: B81C 1/00476 removing a sacrificial layer B81C1/00912 takes precedence

Abstract

A method for releasing from underlying substrate material micromachined structures or devices without application of chemically aggressive substances or excessive forces. The method starts with the step of providing a partially formed device, comprising a substrate layer, a sacrificial layer deposited on the substrate, and a function layer deposited on the sacrificial layer and possibly exposed portions of the substrate layer and then etched to define micromechanical structures or devices therein. The etching process exposes the sacrificial layer underlying the removed function layer material. Next there are the steps of cleaning residues from the surface of the device, and then directing high-temperature hydrogen gas over the exposed surfaces of the sacrificial layer to convert the silicon dioxide to a gas, which is carried away from the device by the hydrogen gas. The release process is complete when all of the silicon dioxide sacrificial layer material underlying the micromachined structures or devices is removed.

Claims

1. A device including micromechanical elements, comprising:

a substrate layer;

a sacrificial layer on at least a first portion of the substrate layer; and

a function layer on at least a second portion of the sacrificial layer;

wherein the function layer is released from the substrate layer by exposing the device to gaseous hydrogen.

2. The device as recited in claim 1, wherein the device is produced in an epitaxy reactor environment.

3. The device as recited in claim 1, wherein the function layer is released from the substrate layer by removing a third portion of the sacrificial layer, the third portion arranged between the function layer and the substrate layer.

4. The device of claim 1, wherein:

at least one of the substrate layer and the function layer include silicon; and

the sacrificial layer includes an oxide bearing material.

5. The device as recited in claim 4, wherein the substrate layer, the sacrificial layer, and the function layer collectively form an SOI wafer.

6. The device as recited in claim 4, wherein:

the sacrificial layer is deposited on the substrate layer; and

the function layer is deposited epitaxially on the sacrificial layer.

7. The device as recited in claim 1, further comprising:

a further sacrificial layer on at least a third portion of the function layer; and

a further encapsulation layer on at least a fourth portion of the further sacrificial layer;

wherein the further sacrificial layer is released from the function layer by exposing the device to gaseous hydrogen.