# US 12,005,523 B2 · Process for nanostructuring the surface of a material by laser

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- Number: US 12,005,523 B2
- Document ID: US12005523B2
- Status: Granted
- Kind: B2
- Application number: 17/257,134
- Filed: 2019-07-12
- Published: 2021-04-29
- Granted: 2024-06-11
- Earliest claimed: 2018-07-13
- Assignees: Universite Jean Monnet Saint Etienne; Centre National de la Recherche Scientifique (CNRS)
- Applicants: Universite Jean Monnet Saint Etienne; Centre National de la Recherche Scientifique (CNRS)
- Inventors: Florent Pigeon; Anthony Abou Saleh; Jean-Philippe Colombier-Cinquantin; Florence Garrelie
- Web page: https://patentgrep.com/patent/US12005523B2

## CPC

- B23K 26/3584: {Increasing rugosity, i.e. roughening}
- B23K 26/0006: {taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence)}
- B23K 26/0624: {using ultrashort pulses, i.e. pulses of 1 ns or less}
- B23K 26/08: Devices involving relative movement between laser beam and workpiece
- B23K 26/355: {Texturing}
- B23K 26/3568: {Modifying rugosity}
- B23K 2103/52: {Ceramics}
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM

## Abstract

The invention relates to a process for nanostructuring the surface of a solid material in order to form a regular pattern of nanostructures on said surface, comprising: irradiating the surface by a plurality of pulse trains (20) of a femtosecond laser beam: each pulse train (20) comprises at least two pulses (21, 22), each pulse has a peak fluence, and a sum of the peak fluences of the pulses of a pulse train is between 10% and 70% of a threshold fluence corresponding to a material ablation threshold for one pulse for said material, two consecutive pulses of a pulse train are separated by a peak-to-peak duration ΔT between 500 fs and 150 ps, two consecutive pulse trains are separated by a duration greater than 10 ΔT, obtaining a regular pattern of nanostructures on said portion of surface, having a spatial periodicity lower than 130 nm.

## Claims

### Claim 1

Process for nanostructuring a surface of a solid material in order to form a regular pattern of nanostructures on said surface, said process comprising:
supplying the solid material, said material comprising the surface;
irradiating a portion of the surface by a femtosecond laser beam, comprising a plurality of pulse trains, wherein:
each pulse train comprises at least two pulses,
each pulse has a peak fluence, and a sum of the peak fluences of the pulses of a pulse train is between 10% and 70% of a threshold fluence corresponding to a material ablation threshold for one pulse for said material,
two consecutive pulses of a pulse train are temporally separated by a peak-to-peak duration ΔT between 500 fs and 150 ps,
two consecutive pulse trains are temporally separated by a duration greater than 10 ΔT,
obtaining of a regular pattern of nanostructures on said portion of the surface, having a spatial periodicity lower than 130 nm,
displacing the femtosecond laser beam on the surface in such a way as to irradiate other portions of said surface.

### Claim 2 (depends on 1)

Process according to claim 1, wherein each pulse has a peak fluence between 5% and 65% of a threshold fluence corresponding to a material ablation threshold for one pulse for said material.

### Claim 3 (depends on 1)

Process according to claim 1, wherein the irradiating by the plurality of pulse trains on a same surface portion represents a total dose less than 6 J/cm2.

### Claim 4 (depends on 1)

Process according to claim 1, wherein each portion of the surface is irradiated by at least 5 pulse trains.

### Claim 5 (depends on 1)

Process according to claim 1, wherein each portion of the surface is irradiated by a number of pulse trains less than 500.

### Claim 6 (depends on 1)

Process according to claim 1, wherein each pulse of a pulse train has a duration less than the duration ΔT between two consecutive pulses of the pulse train.

### Claim 7 (depends on 1)

Process according to claim 1, wherein the material has a crystalline structure, and in particular a face-centred cubic structure.

### Claim 8 (depends on 1)

Process according to claim 1, wherein the material contains diamond-like carbon.

### Claim 9 (depends on 1)

Process according to claim 1, wherein pulses of a pulse train have different linear polarisations when said pulses arrive on the surface.

### Claim 10 (depends on 9)

Process according to claim 9, wherein pulses of a pulse train have linear cross-polarisations.

### Claim 11 (depends on 1)

Process according to claim 1, wherein the nanostructures obtained are nano-pits or nano-holes and/or nano-bumps, forming a regular lattice on the surface.

### Claim 12 (depends on 11)

Process according to claim 11, wherein the nano-pits have a diameter between 10 nm and 40 nm, and preferably between 20 nm and 30 nm.

### Claim 13 (depends on 1)

Process according to claim 1, wherein the irradiated portions of the surface overlap partially.

### Claim 14 (depends on 1)

Process according to claim 1, wherein the material has a thickness less than 200 nm.