Process for filling etched holes

Patent metadata

Field	Value
Publication number	US-9708183-B2
Application number	US-201615046239-A
Country	US
Kind code	B2
Filing date	Feb 17, 2016
Priority date	Feb 17, 2015
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A process for filling one or more etched holes defined in a frontside surface of a wafer substrate. The process includes the steps of: (i) depositing a layer of a thermoplastic first polymer onto the frontside surface and into each hole; (ii) reflowing the first polymer; (iii) exposing the wafer substrate to a controlled oxidative plasma; (iv) optionally repeating steps (i) to (iii); (v) depositing a layer of a photoimageable second polymer; (vi) selectively removing the second polymer from regions outside a periphery of the holes using exposure and development; and (vii) planarizing the frontside surface to provide holes filled with a plug comprising the first and second polymers, which are different than each other. Each plug has a respective upper surface coplanar with the frontside surface.

First claim

The invention claimed is:

1. A process for filling one or more etched holes defined in a surface of a wafer substrate, said process comprising the steps of:
(i) depositing a layer of a thermoplastic first polymer onto the surface and into each hole;
(ii) reflowing the first polymer;
(iii) exposing the wafer substrate to a controlled oxidative plasma so as to reveal the surface;
(iv) optionally repeating steps (i) to (iii);
(v) depositing a layer of a photoimageable second polymer so as to overfill each hole with said second polymer;
(vi) selectively removing the second polymer from regions outside a periphery of the holes to provide overfilled holes, the selective removing comprising exposure and development of the second polymer; and
(vii) planarizing the surface to provide one or more holes filled with a plug comprising the first and second polymers, each plug having a respective upper surface coplanar with the surface of the wafer substrate, wherein the first and second polymers are different.

2. The process of claim 1 , wherein each hole has a depth of at least 10 microns.

3. The process of claim 1 , wherein each hole has an aspect ratio of >1:1.

4. The process of claim 1 , wherein the first polymer is less viscous than the second polymer.

5. The process of claim 1 , wherein, in step (iii), the controlled oxidative plasma exposure is timed so as to remove a predetermined thickness of the first polymer.

6. The process of claim 1 , wherein, in step (vii), the wafer is planarized by a chemical-mechanical planarization (CMP) process.

7. The process of claim 1 , wherein an extent of overfill of the hole immediately prior to step (vii) is less than 12 microns.

8. The process of claim 1 further comprising additional MEMS fabrication steps.

9. The process of claim 8 , wherein the additional MEMS fabrication steps construct inkjet nozzle devices on the planarized surface of the wafer substrate.

10. The process of claim 9 , wherein each nozzle device comprises a nozzle chamber in fluid communication with at least one hole.

11. The process of claim 10 , wherein a respective inlet for each nozzle chamber is defined by one of said holes.

12. The process of claim 11 , further comprising at least one of: wafer thinning and backside etching of ink supply channels.

13. The process of claim 12 , wherein each ink supply channel meets with one or more filled holes.

14. The process of claim 13 , wherein each ink supply channel is relatively wider said one or more holes.

15. The process of claim 14 , further comprising oxidative removal of the first and second polymers from the holes.

Assignees

• Memjet Technology Ltd
• Memjet Technology Ltd

Inventors

• North Angus
• O'Reilly Ronan
• Mcavoy Gregory

Classifications

• B41J2/1645

  thin film formation by spincoating · CPC title

• B41J2/1603 Primary

  of the front shooter type · CPC title

• B41J2/1631

  photolithography · CPC title

• B81C1/00611 Primary

  Processes for the planarisation of structures (planarising depositions C23C, H10) · CPC title

• B41J2/1639

  sacrificial molding · CPC title