Capacitive pressure sensor and method for its production

Patent metadata

Field	Value
Publication number	US-10267700-B2
Application number	US-201515523457-A
Country	US
Kind code	B2
Filing date	Sep 2, 2015
Priority date	Oct 30, 2014
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

A high-precision pressure sensor, having a first base body that has two electrically conductive layers and an insulation layer arranged between the two layers and electrically insulating the two layers from one another, an electrically conductive measurement membrane arranged on the first base body with inclusion of a pressure chamber, which measurement membrane can be charged with a pressure to be measured, and an electrode provided in the membrane-facing layer and spaced apart from the measurement membrane, which electrode together with the measurement membrane forms a capacitor having a capacitance that varies according to the pressure acting upon the measurement membrane. The first base body is characterized in that it has a measurement membrane terminal via which a reference potential can be applied to the measurement membrane, an electrode terminal via which an electrode potential of the electrode can be tapped, and a shield terminal via which a shield potential that can be predetermined independently of the reference potential especially, a shield potential corresponding to the electrode potential can be applied to the layer facing away from the membrane.

First claim

The invention claimed is:

1. A pressure sensor, comprising:
a first base body, having two electrically conductive layers and an insulation layer arranged between said two electrically conductive layers and electrically insulating said two electrically conductive layers from one another;
an electrically conductive measurement membrane that is arranged on said first base body with inclusion of a pressure chamber and that can be charged with a pressure to be measured;
an electrode provided in a membrane-facing layer of said two electrically conductive layers and spaced apart from said electrically conductive measurement membrane, which electrode together with said electrically conductive measurement membrane forms a capacitor having a capacitance that varies as a function of the pressure acting upon said electrically conductive measurement membrane;
a measurement membrane terminal via which a reference potential can be applied to said electrically conductive measurement membrane;
an electrode terminal via which an electrode potential of said electrode can be tapped; and
a shield terminal via which a shield potential that can be predetermined independently of the reference potential, especially, a shield potential corresponding to the electrode potential, can be applied to a layer of said two electrically conductive layers facing away from said electrically conductive measurement membrane, wherein:
said membrane facing layer has an outer edge region connected with said measurement membrane and electrically insulated from said electrode;
an additional insulation layer that electrically insulates an edge region from said electrically conductive measurement membrane is provided between the edge region and said electrically conductive measurement membrane; and
said edge region is connected with said shield terminal via an electrically conductive connection.

2. The pressure sensor according to claim 1 , wherein:
a circuit connected at the input side to said electrode terminal and at the output side to said shield terminal is provided, especially, a circuit having a buffer amplifier, especially, an impedance converter, which circuit in measurement operation:
taps the electrode potential via said electrode terminal connected to it at the input side;
generates a shield potential corresponding to the tapped electrode potential; and
applies the shield potential to said shield terminal connected to it at the output side.

3. The pressure sensor according to claim 1 , wherein:
the reference potential is ground, or a reference potential of a circuit connected to said electrode terminal, especially, to said electrode terminal and said shield terminal.

4. The pressure sensor according to claim 1 , wherein:
said membrane-facing layer has an outer edge region connected with said electrically conductive measurement membrane an electrically insulated from said electrode; and
said electrode terminal comprises an electrode terminal line that extends along a generated surface of a recess provided in said first base body, from a face side of the layer of said two electrically conductive layers facing away from said membrane, said face side facing away from said membrane up to said electrode, said electrode terminal line being electrically insulated from the layer of said two electrically conductive layers facing away from said membrane by an insulation layer arranged between said electrode terminal line and the layer of said two electrically conductive layers facing away from said membrane.

5. The pressure sensor according to claim 1 , wherein:
said first base body has a first recess extending through the layer of said two electrically conductive layers facing away from said membrane and said insulation layer arranged between the layer facing away from the membrane and said membrane-facing layer of said two electrically conductive layers, up to said edge region of said membrane-facing layer of said two electrically conductive layers; and
said shield terminal comprises a shield line that travels along a generated surface of said first recess and, there is an electrically conductive connection with said layer of said two electrically conductive layers facing away from said membrane and said edge region of said membrane-facing layer of said two electrically conductive layers, said first base body has a second recess extending through the layer of said two electrically conductive layers facing away from said membrane, said insulation layers, said edge region of said membrane-facing layer, and said additional insulation layer, up to said electrically conductive measurement membrane;
said membrane terminal comprises a membrane terminal line, that travels to said electrically conductive measurement membrane along a generated surface of said second recess, through said layer of said two electrically conductive layers facing away from said membrane, said insulation layer, and said edge region of the membrane-facing layer, that is electrically insulated, via an insulation layer arranged between said membrane terminal line and said generated surface, from said two electrically conductive layers facing away from the membrane and said edge region of said membrane-facing layer of said two electrically conductive layers, and that is an electrically conductive contact with a region of said electrically conductive measurement membrane that is accessible through said second recess.

6. The pressure sensor according to claim 1 , wherein:
a second base body, connected with said measurement membrane with inclusion of a pressure chamber, is provided on a side of said measurement membrane opposite said first base body;
a first side measurement membrane can be charged with a first pressure via a recess in said first base body that opens into said pressure chamber of said first base body, and a second side of said measurement membrane can be charged with a second pressure via said recess in said second base body that opens into the pressure chamber of said second base body; and
said second base body has:
two electrically conductive layers and an insulation layer arranged between its two layers and insulating said two layers from one another;
an electrode provided in the membrane-facing layer and spaced apart from the measurement membrane, which electrode together with the measurement membrane forms a capacitor having a capacitance that varies as a function of the pressure (Δp) acting upon the measurement membrane;
an electrode terminal via which an electrode potential at which its electrode lies can be tapped; and
a shield terminal via which a shield potential especially, a shield potential corresponding to the electrode potential of its electrode can be applied to the layer facing away from the membrane.

7. The pressure sensor according to claim 6 , wherein:
said membrane-facing layer of said second base body has an outer edge region connected with said electrically conductive measurement membrane and electrically insulated from said electrode;
that is electrically insulated from said electrically conductive measurement membrane, and is connected with said shield terminal of said second base body via an electrically conductive connection; or
that is connected, via an electrically conductive connection, with a membrane terminal traveling across said second base body.

8. A pressure sensor, comprising:
a first base body, having two electrically conductive layers and an insulation layer arranged between said two electrically conductive layers and electrically insulating said two electrically conductive layers from one another;
an electrically conductive measurement membrane that is arranged on said first base body with inclusion of a pressure chamber and that can be charged with a

Assignees

• Endress Hauser Gmbh Co Kg
• Endress Hauser Se Co Kg

Inventors

• Teipen Rafael
• Lemke Benjamin
• Kober Timo
• Karweck Lars
• Rummele-Werner Stefan
• Zieringer Thomas

Classifications

• G01L9/12

  by making use of variations in capacitance {, i.e. electric circuits therefor} · CPC title

• G01L13/025

  using diaphragms · CPC title

• G01L19/04

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title

• G01L9/0073 Primary

  using a semiconductive diaphragm · CPC title

• G01L19/069

  Protection against electromagnetic or electrostatic interferences · CPC title