Curved RF electrode for improved Cmax

• US 9,711,290 B2
• Filed: 09/24/2014
• Issued: 07/18/2017
• Est. Priority Date: 10/02/2013
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Cavendish Kinetics Inc (Qorvo, Inc.)
• Inventors: Maguire, Thomas L., Renault, Mickael, Joshi, Vikram, Van Kampen, Robertus Petrus, Knipe, Richard L.
• Primary Examiner(s): Landau, Matthew
• Assistant Examiner(s): STOWE, SCOTT C
• Application Number:
  US15/024,931
• Publication Number:
  US 20160240320A1
• Time in Patent Office: 1,028 Days
• CPC Class Codes: B81B 2201/0221 Variable capacitors
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 3/0086 Electrical characteristics, e.g. reducing driving voltage, improving resistance to peak voltage
• CPC Class Codes: B81C 1/00166 Electrodes
• CPC Class Codes: B81C 2201/0104 Chemical-mechanical polishing [CMP]
• CPC Class Codes: B81C 2201/0109 Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
• CPC Class Codes: H01G 5/011 Electrodes
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

The present invention generally relates to a MEMS device and a method of manufacture thereof. The RF electrode, and hence, the dielectric layer thereover, has a curved upper surface that substantially matches the contact area of the bottom surface of the movable plate. As such, the movable plate is able to have good contact with the dielectric layer and thus, good capacitance is achieved.

Claims

1. A method of manufacturing a MEMS DVC, comprising:

forming one or more electrodes over a substrate;

depositing a dielectric layer over the electrodes and the substrate;

chemical mechanically polishing the dielectric layer to expose the one or more electrodes, wherein the chemical mechanical polishing results in a convex upper surface of the one or more electrodes; and

forming a plate electrode over the one or more electrodes, wherein the plate electrode has a bottom surface having a concave portion overlying the convex upper surface of the one or more electrodes.

2. The method of claim 1, further comprising:

depositing a second dielectric layer over the chemical mechanically polished dielectric layer and the one or more electrodes.

3. The method of claim 2, wherein the second dielectric layer is conformally deposited.

4. The method of claim 3, wherein the second dielectric layer has a convex surface overlying the convex upper surface of the one or more electrodes.

5. The method of claim 4, further comprising:

depositing a sacrificial layer over the second dielectric layer, wherein the sacrificial layer has a convex surface overlying the convex upper surface of the one or more electrodes.

6. The method of claim 5, wherein forming the plate electrode comprises forming the plate electrode over the sacrificial layer.

7. The method of claim 6, wherein the concave portion is in contact with the convex surface of the sacrificial layer.

8. The method of claim 7, further comprising removing the sacrificial layer.

9. The method of claim 1, wherein the one or more electrodes includes an RF electrode.

10. The method of claim 9, wherein the RF electrode has the convex upper surface.

11. The method of claim 10, wherein the dielectric layer is deposited by PECVD.

12. The method of claim 11, wherein the dielectric layer is selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, silicon dioxide and combinations thereof.