Etching piezoelectric material

• US 9,085,152 B2
• Filed: 05/12/2009
• Issued: 07/21/2015
• Est. Priority Date: 05/22/2008
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Birkmeyer, Jeffrey, Li, Youming
• Primary Examiner(s): Ahmed, Shamim
• Assistant Examiner(s): GATES, BRADFORD M
• Application Number:
  US12/991,901
• Publication Number:
  US 20110117311A1
• Time in Patent Office: 2,261 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B41J 2/161 of film type, deformed by bending and disposed on a diaphragm
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1629 wet etching
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1646 thin film formation by sputtering
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H10N 30/082 by etching, e.g. lithography
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/24917 including metal layer

Abstract

Piezoelectric material is shaped by plasma etching to form deep features with high aspect ratios, and desired geometries.

Claims

1. A method comprising:

forming a NiCr alloy layer as a lower electrode,

providing a PZT piezoelectric material on the NiCr alloy layer,

forming a TiW layer on the PZT piezoelectric material,

providing a mask material comprising a NiCr alloy on the TiW layer, wherein the TiW layer between the mask material and the PZT piezoelectric material improves an adhesion of the mask material to the PZT piezoelectric material,

patterning the mask material by wet etching to form a mask that defines a location of a trench, and

plasma etching the PZT piezoelectric material through the mask to form a feature including the trench in the PZT piezoelectric material, the trench having an aspect ratio of depth to width of about 2;

1 or more and having a depth of about 1 micron or more.

2. The method of claim 1, wherein the trench in the PZT piezoelectric material has the depth of about 5 microns or more.

3. The method of claim 1, wherein the feature formed in the PZT piezoelectric material further includes an island having an edge shape other than a square or a rectangle.

4. The method of claim 1, wherein an etching rate of the plasma etching is about 50 nm/min or more.

5. The method of claim 4, wherein the etching rate of the plasma etching is about 100 nm/min or more.

6. The method of claim 1, wherein the PZT piezoelectric material is poled prior to the plasma etching, and the plasma etching is implemented without depoling the PZT piezoelectric material.

7. The method of claim 1, wherein the plasma etching is implemented while maintaining the PZT piezoelectric material below a Curie temperature of the PZT piezoelectric material.

8. The method of claim 1, wherein in the plasma etching, the mask is etched at a rate about four or more times less than a rate at which the PZT piezoelectric material is etched.

9. The method of claim 1, further comprising removing the mask by wet etching after the plasma etching.

10. The method of claim 1, wherein in the plasma etching, the PZT piezoelectric material is supported on a platen having a temperature of about 100°

C. or less.

11. The method of claim 10, wherein the temperature of the platen is about 30°

C. or less.

12. The method of claim 1, further comprising reducing a thickness of the PZT piezoelectric material after the plasma etching.

13. The method of claim 1, further comprising utilizing the plasma-etched PZT piezoelectric material in an actuator.

14. The method of claim 13, further comprising utilizing the actuator in an ink jet printhead.

15. The method of claim 1, wherein the plasma etching comprises exposing the PZT piezoelectric material through the mask to a gas mixture comprising argon, C₄F₈, and hydrogen (H₂).

16. A method comprising:

forming a NiCr alloy layer as a lower electrode,

providing a PZT piezoelectric material on the NiCr alloy layer,

forming a TiW layer on the PZT piezoelectric material,

depositing a metallic mask material comprising a NiCr alloy on the TiW layer, wherein the TiW layer between the metallic mask material and the PZT piezoelectric material improves an adhesion of the metallic mask material to the PZT piezoelectric material,

patterning the metallic mask material by wet etching to form a mask that defines a location of a trench and a location of an island, and

plasma etching the PZT piezoelectric material through the mask to form the trench and the island in the PZT piezoelectric material, the trench having an aspect ratio of depth to width of about 2 to 1 or more, the island having an edge shape other than a square or a rectangle,

wherein in the plasma etching, the PZT piezoelectric material is supported on a platen having a temperature of about 100°

C. or less.

17. A method of processing piezoelectric material, comprising:

forming a NiCr alloy layer as a lower electrode,

providing a PZT piezoelectric substrate on the NiCr alloy layer,

forming a TiW layer on the PZT piezoelectric substrate,

depositing a mask material comprising a NiCr alloy on the TiW layer, wherein the TiW layer between the mask material and the PZT piezoelectric substrate improves an adhesion of the mask material to the PZT piezoelectric substrate,

patterning the mask material by wet etching to form a mask that defines locations of trenches,

plasma etching the PZT piezoelectric substrate through the mask to form the trenches in the PZT piezoelectric substrate, and

stripping the mask by wet etching after the plasma etching;

wherein the plasma etching comprises using a gas mixture comprising argon, C₄F₈, and hydrogen (H₂).

18. The method of claim 17, wherein the mask material has a thickness of about 10 micron or less.

19. The method of claim 18, wherein the mask has features with an aspect ratio of about 10 to 1 or less.

20. The method of claim 17, wherein at least one of the trenches has a depth of about 5 microns or more.