Micro-lens array and method of making micro-lens array

• US 20040130794A1
• Filed: 12/22/2003
• Published: 07/08/2004
• Est. Priority Date: 05/30/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.), TriQuint Technology Holding Co (Qorvo, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.), TriQuint Technology Holding Co (Qorvo, Inc.)
• Inventors: Houlihan, Francis M., Nalamasu, Omkaram, Kunnavakkam, Madanagopal V., Liddle, James A.
• Granted Patent: US 7,042,645 B2
• Time in Patent Office: Days
• US Class Current: 359/626
• CPC Class Codes: G02B 3/0031 Replication or moulding, e.g. hot embossing, UV-casting, injection moulding
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085

Abstract

A micro-lens array and a method for making are described. The micro-lens array includes a base element and a plurality of lenses formed of an epoxy and including nanoparticles. The micro-lens array is formed from a master micro-lens array, which is placed within a replica micro-lens making assembly. The master micro-lens array is coated with an anti-stiction material prior to having an elastomeric material positioned over it and cured. Removal of the elastomeric material provides a plurality of cavities, which are filled with an epoxy including nanoparticles. Curing of the epoxy finishes the fabrication of the micro-lens array. The lenses of the micro-lens array are formed from a colloidal suspension of nanoparticles and resin.

Claims

1. A micro-lens array, comprising:

a substrate; and

a plurality of micro-lenses formed of a resin on said substrate, wherein said micro-lenses have a hardness of greater than 70 on the D shore scale.

2. The micro-lens array of claim 1, wherein said resin comprises a hydrophobic resin.

3. The micro-lens array of claim 1, wherein said resin is solventless.

4. The micro-lens array of claim 1, wherein said resin exhibits less than 0.2% shrinkage upon cure.

5. The micro-lens array of claim 1, wherein said resin comprises a photocurable resin.

6. The micro-lens array of claim 1, wherein said resin exhibits a refractive index no more than 1% different than a refractive index of said base element.

7. The micro-lens array of claim 1, wherein said resin exhibits a coefficient of thermal expansion no more than about 160 times greater than a coefficient of thermal expansion of said base element.

8. The micro-lens array of claim 1, wherein the resin contains nanoparticles.

9. The micro-lens array of claim 8, wherein said nanoparticles comprise silica nanoparticles.

10. The micro-lens array of claim 9, wherein said nanoparticles comprise nanoparticles having an average size less than about one-tenth the smallest wavelength of light to be utilized with the micro-lens array.

11. The micro-lens array of claim 10, wherein said nanoparticles comprise nanoparticles having an average size less than about one-hundredth the smallest wavelength of light to be utilized with the micro-lens array.

12. The micro-lens array of claim 1, further comprising an anti-reflective coating on said micro-lenses.

13. The micro-lens array of claim 1, wherein said micro-lenses have a hardness in the range of 70 and 88 on the D shore scale.

14. The micro-lens array of claim 1, wherein said base element comprises quartz.

15. A method for forming a micro-lens array, comprising:

applying an anti-stiction coating to a surface of a master micro-lens array including micro-lenses;

providing an elastomeric material over the surface of the master micro-lens array and the micro-lenses;

curing the elastomeric material;

separating the elastomeric material from the master micro-lens array, the elastomeric material having a plurality of cavities defined by the micro-lenses of the master micro-lens array;

filling the cavities with an epoxy;

providing a backing plate to the elastomeric material such that the backing plate covers the cavities;

curing the epoxy; and

separating the backing plate from the elastomeric material such that the epoxy adheres to the backing plate.

16. The method of claim 15, wherein the anti-stiction coating comprises an organosilane.

17. The method of claim 16, wherein the anti-stiction coating comprises an organosilane that comprises (tridecafluoro-1,1,2,2-tetrahydrooctyl)-1-trichlorosilane.

18. The method of claim 15, wherein the elastomeric material is a silicone based elastomeric material.

19. The method of claim 18, wherein said introducing step comprises introducing the elastomeric material to a thickness of at least one millimeter.

20. The method of claim 18, wherein said curing the elastomeric material step comprises:

placing the master micro-lens array within a mold cavity;

introducing the elsatomeric material into the mold cavity;

placing the mold cavity within an enclosure;

covering the enclosure with dimethylsiloxane monomer and a polymerizing catalyst; and

heating the enclosure.

21. The method of claim 15, wherein the elastomeric material is a low-shrinkage epoxy.

22. The method of claim 21, wherein the epoxy comprises a hydrophobic material.

23. The method of claim 22, wherein the epoxy comprises nanoparticles formed of silica.