Condenser microphones based on silicon with humidity resistant surface treatment

• US 5,208,789 A
• Filed: 04/13/1992
• Issued: 05/04/1993
• Est. Priority Date: 04/13/1992
• Status: Expired due to Fees

• Current Assignee: Lectret Precision Pte Ltd. (Intricon Corporation)
• Original Assignee: Lectret S. A.
• Inventors: Ling, Chung H.
• Primary Examiner(s): STEINBERGER, BRIAN
• Application Number:
  US07/867,993
• Time in Patent Office: 386 Days
• Field of Search: 367/181, 367/170, 381/168, 381/174, 381/191, 381/175, 310/308, 310/309, 361/322, 361/313, 361/305
• US Class Current: 367/181
• CPC Class Codes: H04R 19/005 using semiconductor materials

Abstract

An condenser microphone element including a silicon core, a layer of silicon dioxide thereon, and a layer of tantalum pentoxide thereon.

Claims

1. A condenser microphone element comprising

a backplate including a silicon core and a dielectric layer thereon, said dielectric layer including a layer of silicon dioxide on said silicon core and a layer of tantalum pentoxide on said silicon dioxide layer to protect said silicon dioxide layer from humidity, said dielectric layer having a surface exposed to an air cavity, with said surface spaced from a movable electrode, wherein said movable electrode is a diaphragm of a microphone.

2. The microphone element of claim 1 wherein the silicon dioxide layer is 0.2 to 2.0 micrometers thick.

3. The microphone element of claim 2 wherein the silicon dioxide layer is 1.0 to 1.5 micrometers thick.

4. The microphone element of claim 1 wherein the tantalum pentoxide layer is 0.03 to 0.30 micrometer thick.

5. The microphone element of claim 4 wherein the tantalum pentoxide layer is 0.08 to 0.12 micrometer thick.

6. The microphone element of claim 1 wherein said silicon dioxide layer and said tantalum pentoxide layer are charged to provide an electret.

7. A condenser microphone comprising

a backplate including a silicon core and a dielectric layer thereon, said dielectric layer including a layer of silicon dioxide on said silicon core and a layer of tantalum pentoxide on said silicon dioxide layer to protect said silicon dioxide layer from humidity, said dielectric layer having a surface exposed to an air cavity, and a movable electrode supported in spaced relationship with said backplate, wherein said movable electrode is a diaphragm of the microphone, and wherein said movable electrode defines said air cavity between said movable electrode and said dielectric layers.

8. The condenser microphone of claim 7 wherein said diaphragm is a metallized diaphragm.

9. The condenser microphone of claim 7 wherein said diaphragm is a metallized polymer diaphragm.

10. The condenser microphone of claim 7 wherein said diaphragm is a silicon diaphragm.

11. The condenser microphone of claim 7 wherein said core has diaphragm supports formed on one surface and openings through said core.

12. The condenser microphone of claim 7 wherein said silicon dioxide layer and said tantalum pentoxide layer are charged to provide an electret.