Method of fabricating printhead using metal film for protecting hydrophobic ink ejection face

1. A method of fabricating a printhead having a hydrophobic ink ejection face, the method comprising the steps of:

(a) providing a partially-fabricated printhead comprising a plurality of nozzle chambers and a nozzle plate having relatively hydrophilic nozzle surface, said nozzle surface at least partially defining the ink ejection face of the printhead;

(b) defining a plurality of nozzle openings in at least said nozzle plate;

(c) depositing a hydrophobic polymeric layer onto the nozzle surface;

(d) depositing a protective metal film onto at least said polymeric layer;

(e) subjecting said printhead to an oxidizing plasma; and

(f) removing said protective metal film,

thereby providing a printhead having a relatively hydrophobic ink ejection face,

wherein step (b) is performed immediately after any of steps (a), (c) or (d), and wherein no plasma oxidizing steps are performed after removing said protective metal film in step (f).

2. The method of claim 1 , wherein step (b) is performed immediately after step (c), and step (b) comprises: defining a plurality of nozzle openings in said nozzle plate and in said polymeric layer.

3. The method of claim 1 , wherein said protective metal film is comprised of a metal selected from the group comprising: titanium and aluminium.

4. The method of claim 1 , wherein said protective metal film has a thickness in the range of 10 nm to 1000 nm.

5. The method of claim 1 , wherein step (f) is performed by wet or dry etching.

6. The method of claim 1 , wherein step (f) is performed by a wet rinse using peroxide or acid.

7. The method of claim 1 , wherein, in said partially-fabricated printhead, a roof of each nozzle chamber is supported by a sacrificial photoresist scaffold, and wherein said photoresist scaffold by plasma oxidizing prior to removing said protective metal film.

8. The method of claim 1 , wherein step (c) comprises the sub-steps of:

(c)(i) depositing the hydrophobic polymeric layer onto the nozzle surface; and

(c)(ii) photopatterning said polymeric layer so as to define a plurality of nozzle openings in said polymeric layer.

9. The method of claim 8 , wherein photopatterning comprises UV-curing at least some of said polymeric material.

10. The method of claim 1 , wherein step (d) comprises the sub-steps of:

(d)(i) depositing a protective metal film onto at least said polymeric layer; and

(d)(ii) defining a plurality of film openings in said metal film, said film openings being aligned with said nozzle openings.

11. The method of claim 10 , wherein sub-step (d)(ii) comprises the further sub-steps of:

(d)(ii)(1) depositing a mask on said protective metal film;

(d)(ii)(2) patterning said mask so as to unmask said metal film in a plurality of film opening regions; and

(d)(ii)(3) etching said unmasked nozzle opening regions to define said plurality of film openings.

12. The method of claim 1 , wherein one or more backside MEMS processing steps are performed after removing said protective metal film in step (f).

13. The method of claim 12 , wherein said backside MEMS processing steps include defining ink supply channels from a backside of said wafer, said backside being an opposite face to said ink ejection face.

14. The method of claim 1 , wherein a roof of each nozzle chamber is defined at least partially by said nozzle plate.

15. The method of claim 14 , wherein said nozzle plate is spaced apart from a substrate, such that sidewalls of each nozzle chamber extend between said nozzle plate and said substrate.

16. The method of claim 1 , wherein said hydrophobic polymeric layer is comprised of a polymeric material selected from the group comprising: polymerized siloxanes and fluorinated polyolefins.

17. The method of claim 16 , wherein said polymeric material is selected from the group comprising: polydimethylsiloxane (PDMS) and perfluorinated polyethylene (PFPE).