Capacitive pressure sensor and method of manufacture

• US 20050229711A1
• Filed: 04/15/2005
• Published: 10/20/2005
• Est. Priority Date: 04/16/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Ohms, Torsten, Stoll, Oliver
• Granted Patent: US 7,191,661 B2
• Time in Patent Office: Days
• US Class Current: 73/718
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm

Abstract

A capacitive pressure sensor made up of two silicon on insulator (SOI) wafers lying opposite of each other and joined to each other in a vacuum-tight manner, a recess being formed between the two wafers. The first wafer exclusively supports the evaluation circuits required for measuring the applied pressure and a capacitive electrode, and the second wafer has a recess formed by surface micromechanics processes, in which the counter electrode to the capacitive electrode of the first wafer is situated. The second wafer at the same time forms a cover for the first wafer.

Claims

1. A capacitive pressure sensor comprising:

evaluation circuits for measuring an applied pressure;

a capacitive electrode;

a counter electrode; and

first and second silicon on insulator (SOI) wafers lying opposite of each other and being joined to each other in a vacuum-tight manner, a recess being formed between the first and second wafers, the first wafer supporting exclusively the evaluation circuits and the capacitive electrode, the second wafer having the recess formed by surface micromechanics processes, in which the counter electrode to the capacitive electrode of the first wafer is situated, the second wafer forming a cover for the first wafer.

2. The capacitive pressure sensor according to claim 1, wherein the sensor has the form of a needle.

3. The capacitive pressure sensor according to claim 1, wherein an electrical contact between two wafer levels is manufactured using flip-chip technology.

4. The capacitive pressure sensor according to claim 1, wherein the sensor is glazed into a metal lead-through.

5. The capacitive pressure sensor according to claim 4, wherein the sensor is introducible into a housing.

6. The capacitive pressure sensor according to claim 1, further comprising electronics operable above a temperature of 150°

C.

7. A method for manufacturing a capacitive pressure sensor, comprising:

providing a first silicon on insulator (SOI) wafer;

forming a capacitive electrode on the first wafer;

forming an evaluation circuit on the first wafer;

providing a second SOI wafer;

forming a recess on the second wafer;

forming a counter electrode to the capacitive electrode; and

joining the first and second wafers to each other in a vacuum-tight manner such that the recess comes to lie between the first and second wafers.

8. The method according to claim 7, wherein the vacuum-tight joining occurs with the aid of seal glass.

9. The method according to claim 7, wherein an electrical contact between two wafer levels is manufactured using flip-chip technology.

10. The method according to claim 7, wherein the sensor is glazed into a metal lead-through.

11. The method according to claim 10, wherein the sensor is introduced into a housing.