Transforming a valve metal layer into a template comprising a plurality of spaced (nano)channels and forming spaced structures therein

Patent metadata

Field	Value
Publication number	US-11827992-B2
Application number	US-202318153878-A
Country	US
Kind code	B2
Filing date	Jan 12, 2023
Priority date	Jul 18, 2017
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

At least one embodiment relates to a method for transforming at least part of a valve metal layer into a template that includes a plurality of spaced channels aligned longitudinally along a first direction. The method includes a first anodization step that includes anodizing the valve metal layer in a thickness direction to form a porous layer that includes a plurality of channels. Each channel has channel walls and a channel bottom. The channel bottom is coated with a first insulating metal oxide barrier layer as a result of the first anodization step. The method also includes a protective treatment. Further, the method includes a second anodization step after the protective treatment. The second anodization step substantially removes the first insulating metal oxide barrier layer, induces anodization, and creates a second insulating metal oxide barrier layer. In addition, the method includes an etching step.

First claim

What is claimed is:

1. A method for transforming at least part of a valve metal layer into a template comprising a plurality of spaced channels aligned longitudinally along a first direction, the method comprising:
a first anodization step comprising anodizing at least part of the valve metal layer in a thickness direction to form a porous layer of valve metal oxide comprising a plurality of channels, wherein each channel has channel walls aligned longitudinally along the first direction and has a channel bottom, and wherein the channel bottom is coated with a first insulating metal oxide barrier layer as a result of the first anodization step;
a protective treatment, wherein the protective treatment induces hydrophobic surfaces to the channel walls and channel bottoms, and wherein the protective treatment comprises depositing a protective layer on the channel walls and on the channel bottoms;
a second anodization step after the protective treatment, wherein the second anodization step comprises:
removing the first insulating metal oxide barrier layer from the channel bottoms;
removing the protective layer only from the channel bottoms;
inducing anodization only at the bottoms of the plurality of channels; and
creating a second insulating metal oxide barrier layer at the channel bottoms; and

an etching step in an etching solution, wherein the etching step removes the second insulating metal oxide barrier layer from the channel bottoms, and wherein the channel walls maintain hydrophobic surfaces at a conclusion of the etching step.

2. The method according to claim 1 , wherein the valve metal layer comprises a layer of aluminum, an aluminum alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

3. The method according to claim 1 , wherein the protective layer comprises hydrophobic silane or a polymer that is resistant to the etching solution.

4. The method according to claim 1 , wherein the protective layer comprises a polymer, and wherein the polymer comprises polystyrene, poly(methyl 2-methylpropanoate), or poly(dimethylsiloxane).

5. The method according to claim 1 , wherein the etching solution is an aqueous etching solution comprising phosphoric acid, sulfuric acid, oxalic acid, chromic acid, ammonia, hydrogen peroxide, or potassium hydroxide.

6. The method according to claim 1 , wherein the etching solution comprises a surface tension adjusting agent.

7. The method according to claim 1 , further comprising providing ultrasonic waves during the second anodization step.

8. The method according to claim 1 , wherein the first anodization step anodizes only a part of the valve metal layer in the thickness direction to form the template and a substrate supporting the template, and wherein the substrate comprises a remaining, non-anodized part of the valve metal layer.

9. A method for forming a plurality of spaced structures on a substrate, the method comprising:
transforming at least part of a valve metal layer into a template comprising a plurality of spaced channels aligned longitudinally along a first direction to form the template and the substrate, wherein transforming at least part of the valve metal layer into the template comprises:
a first anodization step comprising anodizing at least part of the valve metal layer in a thickness direction to form a porous layer of valve metal oxide comprising a plurality of channels, wherein each channel has channel walls aligned longitudinally along the first direction and has a channel bottom, and wherein the channel bottom is coated with a first insulating metal oxide barrier layer as a result of the first anodization step;
a protective treatment, wherein the protective treatment induces hydrophobic surfaces to the channel walls and channel bottoms, and wherein the protective treatment comprises depositing a protective layer on the channel walls and on the channel bottoms;
a second anodization step after the protective treatment, wherein the second anodization step comprises:
removing the first insulating metal oxide barrier layer from the channel bottoms;
removing the protective layer only from the channel bottoms;
inducing anodization only at the bottoms of the plurality of channels; and
creating a second insulating metal oxide barrier layer at the channel bottoms; and

an etching step in an etching solution, wherein the etching step removes the second insulating metal oxide barrier layer from the channel bottoms, and wherein the channel walls maintain hydrophobic surfaces at a conclusion of the etching step; and

depositing a solid functional material within the channels of the template to form the plurality of spaced structures inside the plurality of spaced channels, wherein the plurality of spaced structures are aligned longitudinally along the first direction.

10. The method for forming a plurality of spaced structures according to claim 9 , wherein depositing the solid functional material comprises depositing an electrically conductive material, a semiconductor material, or an electrically insulating material.

11. The method for forming a plurality of spaced structures according to claim 9 , wherein depositing the solid functional material comprises depositing an electrically conductive material by galvanostatic electrodeposition, potentiostatic electrodeposition, or plating to form a plurality of spaced electrically conductive structures.

12. The method for forming a plurality of spaced structures according to claim 11 , wherein the substrate is an electrically conductive substrate and wherein an electrical contact is established between the plurality of spaced electrically conductive structures and the substrate, and wherein the electrical contact has a contact resistance lower than 1 Ohm cm 2 .

Assignees

• Imec Vzw
• Univ Leuven Kath
• Univ Leuven Kath

Inventors

• Zankowski Stanislaw Piotr
• Vereecken Philippe M

Classifications

• C25D11/045 Primary

  for forming AAO templates · CPC title

• C23F1/20

  for etching aluminium or alloys thereof · CPC title

• C23F1/28

  for etching iron group metals · CPC title

• C25D1/006 Primary

  Nanostructures, e.g. using aluminium anodic oxidation templates [AAO] · CPC title

• C25D1/08

  Perforated or foraminous objects, e.g. sieves (C25D1/10 takes precedence) · CPC title