Pressure sensor with dual chambers

• US 7,568,395 B2
• Filed: 07/29/2007
• Issued: 08/04/2009
• Est. Priority Date: 10/18/2004
• Status: Expired due to Fees

• Current Assignee: Precision Mechatronics Pty Ltd
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Mallinson, Samuel George
• Primary Examiner(s): Allen, Andre J
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US11/829,943
• Publication Number:
  US 20070266794A1
• Time in Patent Office: 737 Days
• Field of Search: 73700-756, 3612831-2834
• US Class Current: 73/729.2
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• 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 9/0072 using variations in capacitance
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass
• CPC Class Codes: G01L 9/125 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

The present invention relates to a pressure sensor. The pressure sensor includes a substrate assembly. The substrate assembly defines sealed channels and includes a conductive layer. A conductive membrane extends from the substrate assembly and is spaced from the conductive layer to form a sealed reference chamber. A cap defines apertures. The cap extends from the substrate assembly to cover the membrane and thereby form an apertured chamber.

Claims

1. A capacitive pressure sensor comprising:

a substrate assembly having a first substrate bonded to a second substrate via an intermediate bonding layer so as to define sealed channels in the first substrate;

a conductive layer on the first substrate;

a conductive membrane extending from the first substrate and spaced from the conductive layer to form a capacitor and a sealed reference chamber having said sealed channels; and

a cap defining apertures, and extending from the first substrate to cover the membrane and form an apertured chamber.

2. A pressure sensor as claimed in claim 1, wherein:

the first substrate is a silicon substrate;

a CMOS layer is deposited on the silicon substrate;

the conductive layer is deposited on the CMOS layer; and

a protective passivation layer is deposited on the conductive layer.

3. A pressure sensor as claimed in claim 2, wherein the passivation layer is formed from an insulating material.

4. A pressure sensor as claimed in claim 2, wherein the passivation layer is formed from a semi-conducting material.

5. A pressure sensor as claimed in claim 2, wherein the CMOS layer has guard rings surrounding the sealed channels to prevent air contained in the sealed channels from corroding circuitry.

6. A pressure sensor as claimed in claim 1, wherein the membrane has a peripheral portion which is located between the substrate assembly and the cap.

7. A pressure sensor as claimed in claim 6, wherein the cap has a peripheral portion on the peripheral portion of the membrane.

8. A pressure sensor as claimed in claim 1, wherein the intermediate bonding layer comprises a low melting point material.

9. A pressure sensor as claimed in claim 8, wherein the low melting point material is selected from the group consisting of:

Au—

Si;

Glass Frit;

Au—

Au;

PDMS;

TiN;

Si₃N₄;

LPCVD PSG;

APCVD BO; and

Boron-Doped Si.