Micromechanical sensor including a single-crystal silicon support

• US 6,076,404 A
• Filed: 01/29/1997
• Issued: 06/20/2000
• Est. Priority Date: 06/03/1993
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Offenberg, Michael, Muchow, Joerg, Muenzel, Horst, Waldvogel, Winfried
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US08/791,106
• Time in Patent Office: 1,238 Days
• Field of Search: 73/514.32, 73/514.33, 73/514.35, 73/514.36, 73/514.38, 73/514.21, 73/514.24, 257/419, 338/2, 338/5, 361/280, 438/52
• US Class Current: 73/514.32
• CPC Class Codes: G01H 11/06 by electric means
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 2015/0817 for pivoting movement of the mass, e.g. in-plane pendulum
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends

Abstract

A micromechanical sensor includes a support of silicon substrate having an epitaxial layer of silicon applied on the silicon substrate. A part of the epitaxial layer is laid bare to form at least one micromechanical deflection part by an etching process. The bared deflection part is made of polycrystalline silicon which has grown in polycrystalline form during the epitaxial process over a silicon-oxide layer which has been removed by etching. In the support region and/or at the connection to the silicon substrate, the exposed deflection part passes into single crystal silicon. By large layer thicknesses, a large working capacity of the sensor is possible. The sensor structure provides enhanced mechanical stability, processability, and possibilities of shaping, and it can be integrated, in particular, in a bipolar process or mixed process (bipolar-CMOS, bipolar-CMOS-DMOS).

Claims

1. A micromechanical sensor, comprising:

a support of silicon substrate having an epitaxial layer of polycrystalline silicon applied thereon, a part of the epitaxial layer being laid bare by an etching process to form at least one micromechanical deflection part, the at least micromechanical deflection part connected, at least one side, to the silicon substrate via a support region made of single-crystal silicon, the at least one micromechanical deflection part being deflected out of an initial position upon application of a force to the micromechanical sensor, the micromechanical sensor further comprising an evaluation circuit for evaluating the deflection of the micromechanical deflection part, wherein the micromechanical deflection part includes a plate supported at its corners, and wherein the micromechanical sensor is a capacitive acceleration sensor with lateral sensitivity.

2. A micromechanical sensor, comprising:

a support of silicon substrate having an epitaxial layer of polycrystalline silicon applied thereon, a part of the epitaxial layer being laid bare by an etching process to form at least one micromechanical deflection part, the at least micromechanical deflection part connected, at least one side, to the silicon substrate via a support region made of single-crystal silicon, the at least one micromechanical deflection part being deflected out of an initial position upon application of a force to the micromechanical sensor, the micromechanical sensor further comprising an evaluation circuit for evaluating the deflection of the micromechanical deflection part, wherein the micromechanical deflection part includes a plate supported at its corners, and wherein the micromechanical sensor is a capacitive acceleration sensor with sensitivity in a direction of detection.

3. A micromechanical sensor comprising:

a single-crystalline silicon substrate having a substrate surface; and

a sensor element arranged on the substrate surface and including at least one polycrystalline silicon deflection part and silicon support regions, the at least one deflection part being deflectable from an initial position upon an application of a force to the sensor element, the at least one deflection part being connected to the silicon substrate via the support regions,

wherein the at least one polycrystalline silicon deflection part is converted into at least one single-crystalline silicon deflection part at the support regions.

4. The micromechanical sensor according to claim 3, further comprising:

a further region having a single-crystalline silicon layer and being provided on the single-crystalline silicon substrate, the further region forming an evaluation circuit for evaluating a deflection of the micromechanical sensor.

5. The micromechanical sensor according to claim 4, wherein the evaluation circuit is a capacitive evaluation circuit.

6. The micromechanical sensor according to claim 4, wherein the evaluation circuit is a piezoresistive evaluation circuit.

7. The micromechanical sensor according to claim 3, wherein the at least one deflection part includes at least one tongue.

8. The micromechanical sensor according to claim 3, wherein the at least one deflection part includes a plate supported at its corners for producing the micromechanical sensor as a capacitive acceleration sensor with at least one of a lateral sensitivity and a sensitivity in a direction of detection.

9. The micromechanical sensor according to claim 3, wherein at least one deflection part includes a plurality of deflection parts made of superimposed epitaxial layers, the plurality of deflection parts being laid bare.

10. The micromechanical sensor according to claim 3, wherein the single-crystalline silicon substrate includes a silicon wafer oriented in one of the crystallographic directions (111) and (100).

11. The micromechanical sensor according to claim 4, further comprising:

a sensor part and an evaluation part, wherein the evaluation circuit is arranged on the single-crystalline silicon substrate, the evaluation circuit including integrated electronic circuits.

12. The micromechanical sensor according to claim 11, wherein the sensor part is electrically isolated from the evaluation part by one of insulation diffusions, trenches and further structural parts on the single-crystalline silicon substrate.