Apparatus and method for fabricating periodic micro-pattern by laser beams

Patent metadata

Field	Value
Publication number	US-9586286-B2
Application number	US-201414497256-A
Country	US
Kind code	B2
Filing date	Sep 25, 2014
Priority date	Nov 7, 2013
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

The invention provides an apparatus for fabricating a periodic micro-pattern by laser beams. The apparatus includes an ultrafast laser light source configured to generate an output laser beam. A diffraction optical element is configured to divide the output laser beam into a plurality of diffractive laser beams. A confocal system is configured to focus the plurality of diffractive laser beams on a focal point, so that the plurality of diffractive laser beams produces an interference light beam with interference phenomena. The interference light beam ablates a surface of an element to fabricate a periodic micro-pattern on the surface of the element. The confocal system includes a first lens, a second lens and a light shielding mask. The plurality of diffractive laser beams passes through the first lens, the light shielding mask and the second lens in sequence.

First claim

What is claimed is:

1. An apparatus for fabricating a periodic micro-pattern by laser beam, comprising:
an ultrafast laser light source configured to generate an output laser beam;
a diffraction optical element configured to divide the output laser beam into a plurality of diffractive laser beams; and
a confocal system configured to focus the plurality of diffractive laser beams on a focal point, so that the plurality of diffractive laser beams produces an interference light beam with interference phenomena, wherein the interference light beam ablates a surface of an element to fabricate a periodic micro-pattern on the surface of the element, wherein the confocal system comprises:
a first lens configured for the plurality of diffractive laser beams being incident thereto to produce a plurality of first collimated laser beams;
a light shielding mask having a plurality of holes, configured for the plurality of first collimated laser beams being incident thereto to produce a plurality of second collimated laser beams; and
a second lens configured to focus the plurality of second collimated laser beams to a focal point of the second lens,
wherein the first lens, the second lens and the light shielding mask are arranged along an optical axis of the output laser beam, and the light shielding mask is disposed between the first lens and the second lens, so that the plurality of diffractive laser beams passes through the first lens, the light shielding mask and the second lens in sequence.

2. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 1 , wherein the plurality of holes of the light shielding mask comprises:
a first hole arranged along an optical axis of the first lens and the second lens; and
a plurality of symmetric holes positioned on a circumference of a circle, wherein the first hole is positioned on a central point of the circle, wherein each of the plurality of symmetric holes is separated from the first hole by a distance that is the same as a radius of the circle, and wherein the plurality of symmetric holes are symmetric to an axis vertical through the first hole.

3. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 2 , wherein a plurality of symmetric holes comprises:
a second hole;
a third hole;
a fourth hole;
a fifth hole;
a sixth hole;
a seventh hole;
an eighth hole; and
a ninth hole, wherein a central angle whose vertex is the first hole and whose sides are radii intersecting the circle in any two adjacent holes of the second to ninth holes is 45 degrees.

4. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , further comprising:
a light blocking element disposed on the light shielding mask, wherein the light blocking element is configured to block one of the first to ninth holes.

5. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 1 further comprising:
a phase shift element disposed in the confocal system, wherein a phase of one of the plurality of diffractive laser beams that passes through the phase shift element is different from a phase of the rest of the plurality of diffractive laser beams without passing through the phase shift element.

6. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 1 , wherein the first lens and the second lens are convex lenses.

7. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 1 , wherein the first lens has a first focal distance, the second lens has a second focal distance, and wherein a ratio of the second focal distance to the first focal distance is between about 0.5 and 2.5.

8. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 2 , wherein an electric field formula of the interference light beam only passing through the first hole is E cos(kz−ωt+φ H ), wherein E is an electric field, k is a wave vector, z is a position vector, ω is an angular velocity, t is time, ω H is a phase shift between one and the rest of the plurality of first collimated laser beams only passing through the first hole.

9. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , wherein an electric field formula of the interference light beam only passing through the second hole is E cos(k cos θ z z−k sin θ y y−ωt+φ A ), wherein E is an electric field, k is a wave vector, y and z are position vectors, ω is an angular velocity, t is time, θz and θy are incident angles of the interference light beam incident to the surface of the element, φ A is a phase shift between one and the rest of the plurality of first collimated laser beams only passing through the second hole.

10. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , wherein an electric field formula of the interference light beam only passing through the third hole is E cos(k cos θ z z+k sin θ y y−ωt+φ B ), wherein E is an electric field, k is a wave vector, y and z are position vectors, ω is an angular velocity, t is time, θz and θy are incident angles of the interference light beam incident to the surface of the element, φ B is a phase shift between one and the rest of the plurality of first collimated laser beams only passing through the third hole.

11. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , wherein an electric field formula of the interference light beam only passing through the fourth hole is E cos(k cos θ z z−k sin θ x x−ωt+φ C ), wherein E is an electric field, k is a wave vector, x and z are position vectors, ω is an angular velocity, t is time, θz and θx are incident angles of the interference light beam incident to the surface of the element, φ C is a phase shift between one and the rest of the plurality of first collimated laser beams only passing through the fourth hole.

12. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , wherein an electric field formula of the interference light beam only passing through the fifth hole is E cos(k cos θ z z+k sin θ x x−ωt+φ D ), wherein E is an electric field, k is a wave vector, x and z are position vectors, ω is an angular velocity, t is time, θz and θx are incident angles of the interference light beam incident to the surface of the element, φ D is a phase shift between one and the rest of the plurality of first collimated laser beams only passing through the fifth hole.

13. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , wherein an electric field formula of the interference light beam only passing through the sixth hole is E cos(k cos θ z z−k sin θ x1 x−k sin θ y1 y−ωt+φ E ), wherein E is an electric field, k is a wave vector, x, y and z are position vectors, ω is an angular velocity, t is time, θz and θx1 and θy1 are incident angles of the interference light beam incident to the surface of the element, φ E is a phase shift between one and the rest of the plurality of first collimated laser beams only passing through the sixth hole.

14. The apparatus for fabricating a periodic micro-pattern by laser beam as claimed in claim 3 , wherein an electric field formula of the interference light beam only passing through the seventh hole is E cos(k cos θ z z+k sin θ x1 x+k sin θ y1 y−ωt+φ F ), wherein E is an electric field, k is a wave vector, x, y and z are position vectors, ω is an angular velocity, t is time, θz and θx1 and θy1 are incident angles of the interference light beam incident to the surface of

Assignees

• Lextar Electronics Corp

Inventors

• Huang Shih-Hsien
• Wang Shih-Hao
• Huang Po-Yuan

Classifications

• B23K26/352

  for surface treatment · CPC title

• B23K26/0648

  comprising lenses · CPC title

• G02B27/425

  in illumination systems (mask illumination systems in photolithographic systems G03F7/70158) · CPC title

• G02B27/46

  Systems using spatial filters · CPC title

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title