METHOD OF FORMING INDIVIDUAL METALLIC MICROSTRUCTURES

• US 20150203969A1
• Filed: 03/13/2013
• Published: 07/23/2015
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The Universit of Minnesota
• Inventors: Oh, Sang-hyun, Johnson, Timothy W.
• Granted Patent: US 9,334,571 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B32B 2311/02 Noble metals
• CPC Class Codes: B32B 43/006 Delaminating
• CPC Class Codes: B81C 1/00111 Tips, pillars, i.e. raised structures microneedles A61M37/0015
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: C23F 1/04 Chemical milling
• CPC Class Codes: G01N 21/01 Arrangements or apparatus for facilitating the optical investigation
• CPC Class Codes: G01N 21/658 enhancement Raman, e.g. surface plasmons
• CPC Class Codes: G01Q 60/22 Probes, their manufacture, or their related instrumentation, e.g. holders
• CPC Class Codes: H01L 21/0259 Microstructure
• CPC Class Codes: H01L 21/02603 Nanowires
• CPC Class Codes: Y10T 156/1168 Gripping and pulling work apart during delaminating

Abstract

Methods for the formation of individual, precisely shaped nano- or micro-scale metallic structures, particularly pyramids. With this technique, mass fabrication of high-quality, uniform, and ultra-sharp pyramids, cones and wedges is achieved. The high yield, reproducibility, durability and massively parallel fabrication methods of this disclosure provide structures suitable for reliable optical sensing and detection and for cementing near-field optical imaging and spectroscopy as a routine characterization.

Claims

1. A method of making a plurality of three-dimensional metallic microstructures, the method comprising:

masking a silicon-based substrate with a mask having a plurality of apertures therethrough;

etching the masked substrate to form a plurality of cavities in the substrate;

depositing a metallic layer over the mask and in the plurality of cavities in contact with the substrate, forming a metallic structure in each of the cavities;

removing the metallic layer from over the mask;

removing the mask from the substrate to provide a plurality of individual metallic microstructures.

2. The method of claim 1 wherein the step of etching the masked substrate comprises crystallographically etching the masked substrate to form a plurality of pyramidal cavities.

3. The method of claim 2 wherein the plurality of pyramidal cavities have a tip angle of 70.52 degrees.

4. The method of claim 1 wherein the step of removing the metallic layer from over the mask comprises physically stripping the metallic layer from the mask.

8. The method of claim 1 wherein the mask is a nitride mask and the step of removing the mask from the substrate comprises using an acidic bath.

9. The method of claim 1 wherein the metallic layer comprises gold, silver, copper, tungsten, tantalum, molybdenum, or titanium.

10. The method of claim 1 wherein the silicon-based substrate is a semiconductor material.

11. The method of claim 10 wherein the semiconductor material is a silicon wafer.

12. The method of claim 1, wherein the resulting plurality of individual metallic microstructures have a tip angle of 70.52 degrees.

13. The method of claim 1, further comprising, prior to depositing the metallic layer, oxidizing a surface of the cavity to provide a plurality of individual metallic microstructures having a tip angle of less than 70 degrees.

14. The method of claim 1, further comprising forming an aperture in the metallic layer in the cavity.

15. The method of claim 14 wherein forming the aperture in the metallic layer comprises focused ion beam (FIB) milling of the metallic layer.

5. A method of making a plurality of three-dimensional metallic microstructures, the method comprising:

masking a silicon-based substrate with a mask having a plurality of apertures therethrough;

etching the masked substrate to form a plurality of cavities in the substrate;

removing the mask from the substrate and applying a photoresist layer over the etched substrate;

depositing a metallic layer over the photoresist and in the plurality of cavities in contact with the substrate, forming a metallic structure in each of the cavities;

removing the photoresist and the metallic layer from the substrate to provide a plurality of individual metallic microstructures.

6. The method of claim 5 wherein the step of etching the masked substrate comprises crystallographically etching the masked substrate to form a plurality of pyramidal cavities.

7. The method of claim 6 wherein the plurality of pyramidal cavities have a tip angle of 70.52 degrees.