Process for filling etched holes using first and second polymers

Patent metadata

Field	Value
Publication number	US-10597290-B2
Application number	US-201916409687-A
Country	US
Kind code	B2
Filing date	May 10, 2019
Priority date	Feb 17, 2015
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

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: depositing a layer of a thermoplastic first polymer onto the frontside surface and into each hole until the holes are overfilled with the first polymer; depositing a layer of a photoimageable second polymer different than the first polymer; selectively removing the second polymer from regions outside a periphery of the holes; exposing the wafer substrate to a controlled oxidative plasma so as to reveal the frontside surface of the wafer substrate; and planarizing the frontside surface to provide holes filled with a plug of the first polymer only, each plug having 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 frontside surface of a wafer substrate, the process comprising the steps of:
(i) depositing a layer of a thermoplastic first polymer onto the frontside surface and into each hole;
(ii) optionally reflowing the first polymer;
(iii) optionally repeating steps (i) and (ii) until the holes are overfilled with the first polymer;
(iv) depositing a layer of a photoimageable second polymer;
(vi) selectively removing the second polymer from regions outside a periphery of the holes, the selective removing comprising exposure and development of the second polymer;
(vii) exposing the wafer substrate to a controlled oxidative plasma so as to reveal the frontside surface of the wafer substrate; and
(viii) planarizing the frontside surface to provide one or more holes filled with a plug comprising the first polymer only, each plug having a respective upper surface coplanar with the frontside surface,
wherein the first polymer is less viscous than the second polymer.

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, in step (viii), the wafer is planarized by a chemical-mechanical planarization (CMP) process.

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

6. The process of claim 1 , further comprising the step of:
exposing the wafer substrate to a controlled oxidative plasma so as to reveal the frontside surface of the wafer substrate after step(i).

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

8. The process of claim 7 , wherein the additional MEMS fabrication steps construct inkjet nozzle devices on the planarized surface of the wafer substrate.

9. The process of claim 8 , wherein each nozzle device comprises a nozzle chamber in fluid communication with at least one hole.

10. The process of claim 9 , wherein a respective inlet for each nozzle chamber is defined by one of said holes.

11. The process of claim 10 , further comprising at least one of: wafer thinning and backside etching of ink supply channels.

12. The process of claim 11 , wherein each ink supply channel meets with one or more filled holes.

13. The process of claim 12 , wherein each ink supply channel is relatively wider than said one or more holes.

Assignees

• Memjet Technology Ltd

Inventors

• North Angus
• O'Reilly Ronan
• Mcavoy Gregory

Classifications

• B81C2201/0121

  involving addition of material followed by removal of parts of said material, i.e. subtractive planarization · CPC title

• B81B2203/0353

  Holes · CPC title

• B41J2/1639

  sacrificial molding · CPC title

• B41J2/1645

  thin film formation by spincoating · CPC title

• B81C1/00087

  Holes · CPC title