Suspended high reflectivity coating on release structure and fabrication process therefor

• US 20020168136A1
• Filed: 05/08/2001
• Published: 11/14/2002
• Est. Priority Date: 05/08/2001
• Status: Active Grant

• Current Assignee: Excelitas Technologies Corporation (Excelitas Technologies Holdings LLC)
• Original Assignee: Axsun Technologies Incorporated
• Inventors: Atia, Walid A., Le, Minh Van
• Granted Patent: US 6,808,276 B2
• Time in Patent Office: Days
• US Class Current: 385/18
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 2006/12109 Filter
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02B 6/3516 the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833

Abstract

In a MOEMS device and corresponding fabrication process, absorbing material along the optical axis of the device is removed. The result is a suspended optical coating, such as a dielectric thin film mirror stack. Such optical coatings can have very low absorption. Thus, the invention can materially lower the net absorption in the device, and thereby improve performance, by degrading power related dependencies.

Claims

1. A process for fabricating a micro-optical electromechanical system device, the process comprising:

depositing an optical coating that is supported by a device layer;

removing a sacrificial layer to form a release structure in the device layer along an optical axis; and

forming a device layer port by removing a portion of the device layer in a region around the optical axis.

2. A process as claimed in claim 1, wherein the step of depositing the optical coating comprises depositing a high reflectivity coating.

3. A process as claimed in claim 1, wherein the step of depositing the optical coating comprises depositing a dielectric thin film coating.

4. A process as claimed in claim 1, wherein the step of depositing the optical coating comprises depositing a dielectric thin film coating having greater than six layers.

5. A process as claimed in claim 1, further comprising installing a mirror structure opposite the optical coating.

6. A process as claimed in claim 1, wherein the step of removing the sacrificial layer comprises etching the sacrificial layer from a region between the device layer and a support.

7. A process as claimed in claim 6, further comprising forming a support optical port through the support along the optical axis.

8. A process as claimed in claim 1, further comprising depositing a sacrificial layer on the device layer and then depositing the optical coating on the etch-stop layer;

9. A process as claimed in claim 8, wherein the step of forming the device layer port comprises etching through the device layer to the etch-stop layer.

10. A process as claimed in claim 9, further comprising removing the etch-stop layer from the region of the device layer port.

11. A process as claimed in claim 1, further comprising forming the device layer port in the device layer and then depositing the optical coating into the device layer port.

13. A device as claimed in claim 12, wherein the first mirror structure and the second mirror structure each comprise a dielectric thin film coating.

14. A device as claimed in claim 12, wherein the first mirror structure is suspended on the deflectable structure across the optical port in the deflectable structure.

15. A device as claimed in claim 12, wherein the support comprises silicon wafer material.

16. A device as claimed in claim 12, further comprising an insulating layer between the support and the deflectable structure.

17. A device as claimed in claim 16, wherein insulating layer functions as an electrostatic drive cavity spacer.

18. A device as claimed in claim 12, wherein the optical port is sized in response to a mode field diameter of light resonating in the optical cavity.

12. A MOEMS device, comprising:

at least first mirror structure and a second mirror structure defining an optical cavity;

a support; and

a deflectable structure on the support that holds the first mirror structure, the deflectable structure being located on an external side of the first mirror structure relative to the optical cavity, the deflectable structure having an optical port in a region around an optical axis of the optical cavity.