# US 12,007,695 B2 · Rapid large-scale fabrication of metasurfaces with complex unit cells

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- Number: US 12,007,695 B2
- Document ID: US12007695B2
- Status: Granted
- Kind: B2
- Application number: 17/150,171
- Filed: 2021-01-15
- Published: 2021-07-15
- Granted: 2024-06-11
- Earliest claimed: 2020-01-15
- Assignees: Board of Regents, The University of Texas System
- Applicants: Board of Regents, the University of Texas System
- Inventors: Robert Magnusson; Kyu Lee; Hafez Hemmati; Pawarat Bootpakdeetam
- Web page: https://patentgrep.com/patent/US12007695B2

## CPC

- G03F 7/70408: {Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect}
- G03F 7/0035: {Multiple processes, e.g. applying a further resist layer on an already in a previously step, processed pattern or textured surface}
- G03F 7/094: {Multilayer resist systems, e.g. planarising layers}
- G03F 7/162: {Coating on a rotating support, e.g. using a whirler or a spinner}
- G03F 7/2053: {using a laser (ablative removal B41C)}
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

A method of fabricating a metasurface comprises coating a photoresist film onto a substrate and loading the coated substrate into a laser interference lithography setup, exposing the photoresist film via a laser with a first interference pattern, the first interference pattern having a first period and a first exposure energy, subsequently exposing the coated substrate with a second interference pattern, the second interference pattern having a second period and a second exposure energy, developing the exposed portions of the photoresist film to form a periodic pattern in the photoresist, and transferring the periodic pattern into the substrate, the substrate supporting an appropriate film system that embodies the final metasurface device.

## Claims

### Claim 1

A method of fabricating a metasurface, the method comprising:
providing a photoresist film disposed on a substrate;
exposing the photoresist film with a first interference pattern, the first interference pattern having a first period and a first exposure energy;
exposing the photoresist film with a second interference pattern, the second interference pattern having a second period and a second exposure energy;
rotating the substrate;
exposing the photoresist film with a third interference pattern, the third interference pattern having a third period and a third exposure energy;
exposing the photoresist film with a fourth interference pattern, the fourth interference pattern having a fourth period and a fourth exposure energy; and
generating a two-dimensional periodic metasurface,
wherein the first interference pattern and the second interference pattern are disposed along the same dimension;
wherein the third interference pattern and the fourth interference pattern are disposed along the same dimension
wherein the first period and the second period have a least common multiple (LCM) such that a final metasurface period is larger than either of the first period and the second period; and
wherein the third period and the fourth period have a least common multiple (LCM) such that a final metasurface period is larger than either of the third period and the fourth period.

### Claim 2 (depends on 1)

The method of claim 1, further comprising spin-coating the photoresist film onto the substrate.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
developing the exposed portions of the photoresist film to form a two-dimensional periodic pattern; and
transferring the two-dimensional periodic pattern to the substrate.

### Claim 4 (depends on 1)

The method of claim 1, wherein the substrate comprises a single film layer of at least one of a dielectric and a semiconductor.

### Claim 5 (depends on 1)

The method of claim 1, wherein the substrate comprises a system of film layers.

### Claim 6 (depends on 1)

The method of claim 1, wherein the substrate comprises at least one of silicon-on-quartz, silicon-on-insulator, germanium, zinc selenide, and zinc sulfide.

### Claim 7 (depends on 1)

The method of claim 1, wherein the first period and the first exposure energy are equal to the third period and the third exposure energy.

### Claim 8 (depends on 1)

The method of claim 1, wherein the second period and the second exposure energy are equal to the fourth period and the fourth exposure energy.

### Claim 9 (depends on 1)

The method of claim 1, wherein the substrate is rotated 90 degrees.

### Claim 10 (depends on 1)

The method of claim 1, wherein the substrate is rotated 60 degrees.