COATED OPTICAL ELEMENT COMPONENT WITH A COATED OPTICAL ELEMENT AND METHOD TO PRODUCE THE SAME

• US 20190330054A1
• Filed: 04/25/2019
• Published: 10/31/2019
• Est. Priority Date: 04/27/2018
• Status: Active Application

• Current Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Original Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Inventors: Ackermann, Marcelo David, Garnier, Michael Gunnar, Apitz, Dirk, Brauneck, Ulf Georg
• Application Number:
  US16/394,722
• Publication Number:
  US 20190330054A1
• Time in Patent Office: Days
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 7/0067 for controlling the passage of optical signals through the package
• CPC Class Codes: B81C 1/00317 Packaging optical devices
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/031 Anodic bondings
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

An optical element includes an optically transparent substrate of alkali containing glass and a coating on a surface, the coating enabling anodic bonding of the alkali containing glass within an area of the surface that is covered with the coating and with the anodic bond forming at the outer surface of the coating.

Claims

1. An optical element, comprising:

an optically transparent substrate of alkali containing glass; and

a coating on a surface of the substrate, the coating enabling anodic bonding of the alkali containing glass within an area of the surface that is covered with the coating and with the anodic bond forming at an outer surface of the coating.

2. The optical element of claim 1, wherein the coating is alkali-free at least at its outer surface.

3. The optical element of claim 1, wherein the outer surface of the coating is hydrophilic or polar.

4. The optical element of claim 1, wherein the outer surface of the coating comprises:

SiO₂, SiO_x, Al₂O₃, or AlO_x;

a metal;

a metal oxide;

a fluoride;

a sulfide;

or

mixtures thereof.

5. The optical element of claim 1, wherein the substrate has a face that is fully covered by the coating.

6. The optical element of claim 1, wherein a thickness of the coating is in the range of from 2 nm to 50 μ

m.

7. The optical element according to claim 1, wherein the coating comprises at least two layers.

8. The optical element of claim 7, wherein the at least two layers comprises a layer of a non-bonding material that does not bond to other surfaces by anodic bonding and a further layer of a material that enables anodic bonding of the alkali containing glass on the area of the surface that is covered with the coating.

9. The optical element of claim 8, wherein the further layer has a thickness of between 1 nm and 20 nm.

10. The optical element of claim 7, wherein a thickness of a topmost layer of the coating is in the range of from 50 nm to 1000 nm.

11. The optical element of claim 1, wherein a roughness (Rq) of the outer surface of the coating is between 0.1 and 2 nm RMS.

12. The optical element of claim 1, wherein the coating is:

an anti-reflection coating;

a mirrors coating with or without at least one protection layer;

or

a filter coating.

13. The optical element of claim 1, wherein the coating comprises a nitride, an oxynitride, a carbonitride, a carbide, or a mixture thereof.

14. A component, comprising:

an optical element with an optically transparent substrate of alkali containing glass;

a coating on a surface of the substrate; and

a second substrate connected to the optically transparent substrate, the second substrate being connected to the optically transparent substrate by an anodic bond at an area of the surface covered with the coating so that the coating is arranged between the optically transparent substrate and the second substrate and is in direct contact with both the optically transparent substrate and the second substrate.

15. The component of claim 14, wherein the second substrate comprises a silicon part, a silicon oxide covered silicon part, or a metal part that is bonded to the optical element.

16. The component of claim 14, wherein the component is a MEMS-device.

17. The component of claim 14, wherein the glass of the substrate has an alkali depletion zone at an interface to the coating.

18. The component of claim 14, wherein the optical element is a window with a substrate having two opposite plane parallel faces.

19. The component of claim 14, wherein a bond strength of the anodic bond between the coating and the second substrate exceeds 7 MPa.

20. The component of claim 14, wherein the coating has at least one of the following properties:

a material of the coating is not capable of being anodically bonded;

the coating itself does not contain alkali ions in sufficient amount to establish a charge depletion zone at an interface of the anodic bond;

or

an alkali content of the coating in mol-% is less than 1/10th of an alkali content of the alkali containing glass.

21. A wafer package, comprising:

an optically transparent wafer;

a second wafer with a plurality of optoelectronic or optomechanical elements; and

a coating covering a side of the optically transparent wafer facing the second wafer, the optically transparent wafer and the second wafer being bonded together at bonding areas with anodic bonding, the coating extending across the bonding areas so that the coating contacts the second wafer and the anodic bonds are formed between the coating and the second wafer.

22. A method for fabricating a component with an optical element, the method comprising:

providing an optically transparent substrate of an alkali containing glass;

depositing a coating on a surface of the substrate, the coating enabling anodic bonding of the alkali containing glass on an area of the surface that is covered with the coating;

bringing a second substrate into contact with the coating on the optically transparent substrate;

heating the optically transparent substrate up to a temperature that enables diffusion of alkali ions in the glass; and

applying a voltage across a stack of the optically transparent substrate and the second substrate so that alkali ions migrate within the bulk of the glass creating an alkali depletion zone and the optically transparent substrate with coating under the influence of the electrostatic field generated by the applied voltage and ion depletion zone at an interface and the second substrate are bonded together.

23. The method of claim 22, wherein:

a stack of the substrate and the coated glass is heated to a temperature above 250°

C. but below a glass transition temperature Tg of the glass;

the voltage applied to generate the electric field is above 250V; and

a bond strength is achieved surpassing a fracture strength of the glass of the transparent substrate.