Method for fabricating a through-wafer optical MEMS device having an anti-reflective coating

• US 20030021004A1
• Filed: 12/19/2001
• Published: 01/30/2003
• Est. Priority Date: 12/19/2000
• Status: Abandoned Application

• Current Assignee: Coventor, Inc. (Lam Research Corporation)
• Original Assignee: Coventor, Inc. (Lam Research Corporation)
• Inventors: Tatic-Lucic, Svetlana, DeReus, Dana R., Cunningham, Shawn Jay
• Application Number:
  US10/025,182
• Publication Number:
  US 20030021004A1
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/038 Microengines and actuators not provided for in B81B2201/031 - B81B2201/037
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: B81B 7/0067 for controlling the passage of optical signals through the package
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2203/0109 Bonding an individual cap on the substrate
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 26/0866 the reflecting means being moved or deformed by thermal means
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/353 the optical element being a shutter, baffle, beam dump or opaque element absorbers on light guide termination G02B6/243
• CPC Class Codes: G02B 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/3566 involving bending a beam, e.g. with cantilever
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3572 Magnetic force magnetic forces controlling reflecting elements in general G02B26/085; magneto-optic devices G02F1/09
• CPC Class Codes: G02B 6/3576 : Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/3578 : Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• CPC Class Codes: G02B 6/3582 : Housing means or package or arranging details of the switching elements, e.g. for thermal isolation
• CPC Class Codes: G02B 6/3584 : constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: H01H 2001/0052 : Special contact materials used for MEMS
• CPC Class Codes: H01L 2224/48091 : Arched
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

An optical MEMS device is fabricated in either a surface or bulk micromachining process wherein an integral process step entails providing an antireflective coating on one or more surfaces of a substrate through which optical information is to be transmitted. In one method, a surface micromachining process is carried out in which a sacrificial layer is formed and patterned on an optically transmissive substrate. A structural layer is formed on the sacrificial layer and fills in regions of the sacrificial layer that have been removed. An amount of the sacrificial layer is removed sufficient to define and release a microstructure and thereby render the microstructure movable for interaction with an optical signal directed toward the optically transmissive substrate. In another method, a bulk micromachining process is carried out in which a first substrate is provided that is composed of an optically transmissive material. An antireflective coating is deposited on a major surface of the first substrate to enable an optical signal to be transmitted along a path directed through the antireflective coating and the first substrate. A movable, actuatable microstructure is formed a second substrate. The first and second substrates are aligned and bonded together in a manner enabling the microstructure to interact with the optical signal upon actuation of the microstructure.

Claims

1. A method for fabricating an optical MEMS device comprising the steps of:

(a) providing an optically transmissive substrate;

(b) depositing an antireflective coating on a surface of the substrate to enable an optical signal to be transmitted along a path directed through the antireflective coating and the substrate; and

(c) forming a movable, actuatable microstructure on the substrate, whereby actuation of the microstructure causes the microstructure to interact with the optical signal.

2. The method according to claim 1 wherein the substrate is composed of a material selected from the group consisting of silicon, silica, glass, quartz, sapphire, zinc oxide, alumina, Group III-V compounds, and alloys thereof.

3. The method according to claim 1 comprising the step of depositing a second antireflective coating on a second opposing surface of the substrate.

4. The method according to claim 1 comprising the step of forming a conductive element on the substrate.

5. The method according to claim 1 wherein the step of forming the microstructure comprises forming a patterned sacrificial layer on the substrate wherein at least a portion of the substrate is exposed, forming a structural layer on the sacrificial layer and on the exposed portion of the substrate, and removing at least a portion of the sacrificial layer to render the microstructure movable.

6. The method according to claim 1 comprising the step of forming an optically reflective element on the microstructure.

7. An optical MEMS device fabricated according to the method of claim 1.

8. A method for fabricating an optical MEMS device comprising the steps of:

(a) providing a first substrate composed of an optically transmissive material;

(b) depositing an antireflective coating on a surface of the first substrate to enable an optical signal to be transmitted along a path directed through the antireflective coating and the first substrate;

(c) forming a movable, actuatable microstructure on a second substrate; and

(d) bonding the second substrate to the first substrate, whereby the first and second substrates are aligned to enable the microstructure to interact with the optical signal upon actuation of the microstructure.

9. The method according to claim 8 wherein the substrate is composed of a material selected from the group consisting of silicon, silica, glass, quartz, sapphire, zinc oxide, alumina, Group Ill-V compounds, and alloys thereof.

10. The method according to claim 8 comprising the step of depositing a second antireflective coating on a second opposing surface of the first substrate.

11. The method according to claim 8 comprising the step of forming a conductive element on the first substrate.

12. The method according to claim 11 comprising the step of forming a channel in the second substrate whereby, after the bonding step, the conductive element formed on the first substrate is electrically isolated.

13. The method according to claim 8 wherein the second substrate comprises an etch-stop layer interposed between first and second bulk layers.

14. The method according to claim 13 comprising the step of removing at least a portion of the etch-stop layer to render the microstructure movable.

15. The method according to claim 8 comprising the step of doping a conductive region of the second substrate to enhance electrical conductivity of the conductive region.

16. The method according to claim 15 comprising the steps of forming a first contact on the second substrate in communication with the conductive region, and forming a second contact on the first substrate whereby, after the bonding step, the first contact communicates with the second contact.

17. The method according to claim 8 comprising the step of forming an optically reflective element on the microstructure.

18. The method according to claim 8 wherein the step of bonding comprises the step of performing a bonding technique selected from the group consisting of anodic bonding, fusion bonding, glass-frit bonding, eutectic bonding, and adhesive bonding.

19. An optical MEMS device fabricated according to the method of claim 8.