Programmable deposition of thin films of a user-defined profile with nanometer scale accuracy

Patent metadata

Field	Value
Publication number	US-9415418-B2
Application number	US-201414462198-A
Country	US
Kind code	B2
Filing date	Aug 18, 2014
Priority date	Aug 19, 2013
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

An inkjet-based process for programmable deposition of thin films of a user-defined profile. Drops of a pre-cursor liquid organic material are dispensed at various locations on a substrate by a multi-jet. A superstrate that has been bowed due to a backside pressure is brought down such that a first contact of the drops is made by a front side of the superstrate thereby initiating a liquid front that spreads outward merging with the drops to form a contiguous film captured between the substrate and the superstrate. A non-equilibrium transient state of the superstrate, the contiguous film and the substrate then occurs after a duration of time. The contiguous film is then cured to crosslink it into a polymer. The superstrate is then separated from the polymer thereby leaving a polymer film on the substrate. In such a manner, non-uniform films can be formed without significant material wastage in an inexpensive manner.

First claim

The invention claimed is:

1. A process for depositing thin films, the process comprising:
dispensing drops of a pre-cursor liquid organic material at a plurality of locations on a substrate by an array of inkjet nozzles;
bringing down a superstrate thereby allowing said drops to form a contiguous film captured between said substrate and said superstrate;
selecting parameters of said superstrate to enable increased time to an equilibrium state thereby enabling capture of non-equilibrium transient states of said superstrate, said contiguous film and said substrate;
curing said contiguous film to solidify it into a solid; and
separating said superstrate from said solid thereby leaving a polymer film on said substrate.

2. The process as recited in claim 1 further comprising:
bringing down said superstrate that has been bowed due to a backside pressure such that a first contact on said drops is made by a front side of said superstrate thereby initiating a liquid front that spreads outward merging with said drops to form said contiguous film.

3. The process as recited in claim 2 further comprising:
bringing down said superstrate such that said first contact on said drops is made by said front side of said superstrate in a local atmosphere of gases that are soluble in organic liquids.

4. The process as recited in claim 2 further comprising:
bringing down said superstrate such that said first contact on said drops is made by said front side of said superstrate in a local atmosphere of helium or carbon dioxide.

5. The process as recited in claim 1 , wherein said superstrate is porous and allows trapped gases to be transmitted.

6. The process as recited in claim 1 , wherein said superstrate comprises a material of glass, ceramics, polymers or combinations thereof.

7. The process as recited in claim 1 , wherein a surface of said superstrate is coated with a low surface energy coating, wherein a surface of said substrate is coated with an adhesion promoter.

8. The process as recited in claim 1 , wherein said contiguous film is cured by photonic or thermal energy to solidify said contiguous film into said polymer.

9. The process as recited in claim 1 , wherein said contiguous film is cured by exposure to ultraviolet radiation through said substrate or said superstrate.

10. The process as recited in claim 1 , wherein said superstrate is a roll of plastic held under tension.

11. The process as recited in claim 10 , wherein said substrate is composed of a material with a Young's modulus greater than 1 GPa.

12. The process as recited in claim 10 , wherein said substrate is a rigid wafer composed of one or more of the following materials: silicon, silicon dioxide and gallium nitride.

13. The process as recited in claim 10 , wherein a first portion of said roll of plastic is used as a first superstrate, wherein a second portion of said roll of plastic is used as a second superstrate.

14. The process as recited in claim 10 , wherein said substrate is a roll of plastic.

15. The process as recited in claim 14 , wherein said substrate is held against a vacuum or a porous chuck.

16. The process as recited in claim 14 , wherein said substrate is more rigid than said superstrate.

17. The process as recited in claim 14 , wherein a ratio of an effective bending rigidity of substrate to said superstrate exceeds 5.

18. The process as recited in claim 1 , wherein said superstrate comprises fused silica wafers, wherein an outer ring of said wafers has a higher thickness in comparison to an inner ring of said wafers which interacts with said drops of said pre-cursor liquid organic material.

19. The process as recited in claim 1 further comprising:
depositing multi-material stacks on said substrate by using different inkjettable materials.

20. The process as recited in claim 19 , wherein a set of inkjet nozzles deposits said multi-material stacks on said substrate, wherein one or more inkjet nozzles in said set of inkjet nozzles have a different material.

21. The process as recited in claim 1 , wherein said superstrate has an effective bending rigidity with an optimal range defined by being higher than a minimum required to create merging of said drops while lower than a maximum required to ensure that said contiguous film does not equilibrate prior to a designed duration of time following said bringing down of said superstrate.

22. The process as recited in claim 21 , wherein a pre-equilibrium transient of said contiguous film creates a film thickness profile whose volume distribution is a function of a volume distribution of said drops dispensed on said substrate.

23. The process as recited in claim 1 , wherein a location and a volume of said dispensed drops on said substrate are obtained by solving an inverse optimization to minimize a norm of error between an actual film thickness profile and a desired film thickness profile.

24. The process as recited in claim 23 , wherein said inverse optimization includes discrete variables associated with drop volumes and/or drop locations.

25. The process as recited in claim 1 further comprising:
etching said polymer film to allow a transfer of a film thickness profile to an underlying functional film or said substrate.

26. The process as recited in claim 1 , wherein a minimum volume of drops dispensed is below 5 picoliters using either piezo jets or electro hydro dynamic jets.

27. The process as recited in claim 1 , wherein a minimum volume of drops dispensed is below 1 picoliter using either piezo jets or electro hydro dynamic jets.

28. A process for depositing intentionally non-uniform films, the process comprising:
obtaining a desired non-uniform film thickness profile;
solving an inverse optimization program to obtain a volume and a location of dispensed drops so as to minimize a norm of error between said desired non-uniform film thickness profile and a final film thickness profile such that a volume distribution of said final film thickness profile is a function of said volume and said location of said dispensed drops;
dispensing said drops of a pre-cursor liquid organic material at a plurality of locations on a substrate by an array of inkjet nozzles;
bringing down a superstrate to form a contiguous film captured between said substrate and said superstrate;
obtaining a time to a non-equilibrium transient state of said superstrate, said contiguous film and said substrate by using said inverse optimization scheme;
curing said contiguous film to solidify it into a polymer; and
separating said superstrate from said polymer thereby leaving a polymer film on said substrate.

29. The process as recited in claim 28 , wherein said process is used for polishing a topography of said substrate.

30. The process as recited in claim 29 , wherein said desired non-uniform film thickness profile is designed to compensate said topography of said substrate.

31. The process as recited in claim 28 , wherein said desired non-uniform film thickness profile is given by a desired surface profile on said substrate and a starting substrate measured topography.

32. The process as recited in claim 31 , wherein said process is used for compensating process parasitics comprising one or more of the following: evaporation, shrinkage and etch back.

33

Assignees

• Univ Texas

Inventors

• Sreenivasan Sidlgata V
• Singhal Shrawan

Classifications

• H10P76/20

  of masks comprising organic materials · CPC title

• B05D3/067 Primary

  Curing or cross-linking the coating · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B29C35/0888

  using transparant moulds · CPC title

• B05D3/0254

  After-treatment · CPC title