WO2006067778A1

WO2006067778A1 - System and method for the fabrication of an electro-optical module

Info

Publication number: WO2006067778A1
Application number: PCT/IL2005/000208
Authority: WO
Inventors: Amotz Shemi; Yacov Malinovich; Eli Arad
Original assignee: Color Chip Israel Ltd
Current assignee: Color Chip Israel Ltd
Priority date: 2004-02-18
Filing date: 2005-02-20
Publication date: 2006-06-29
Anticipated expiration: 2006-08-18
Also published as: JP2007523378A; EP1723456B1; US20090016670A1; JP4859677B2; US7668414B2; EP1723456A1; KR20070085080A; EP1723456A4

Abstract

A system and method for fabricating an electro-optical hybrid module (100). The electro-optical hybrid module (100) may comprise an electro-optical component, an electronic component (110), a planar light wave circuit (PLC) embedded with at least an optical waveguide (120). The electro-optical component may transmit or receive energy through a micro-folding mirror (160) while the electronic component may amplify and transfer an electric signal to the electro-optical component. The planar light wave circuit may typically provide an opto-electronic signal communication path via the plurality of optical waveguides that may be embedded in the planar light wave circuit.

Description

SYSTEM AND METHOD FOR THE FABRICATION OF AN ELECTRO-

OPTICAL MODULE

BACKGROUND OF THE INVENTION

[001] Optical communication systems may be configured to allow for the propagation

of signals between desirable locations. The signals may propagate, through portions of the

communication system, along an optical path. An opto-electronic module may typically be

used in such optical communication systems such as for example a fiber optic

communication system. The opto-electronic module may typically be used for transferring

electrical energy and signals to light energy and signals or vice versa. This opto-electronic

module may combine optical elements, electrical components, an optical waveguide, and

an electrical circuit in order to implement the desired energy transferring capabilities.

[002] Optical fiber may typically be used to guide optical signals in optical communication systems such as for example wavelength division multiplexing (WDM)

optical communication systems. There exists a technological limitation in manufacturing a multi-path optical fiber for guiding several optical signals. Currently, a planar light

waveguide circuit (PLC) combines several optical units with optical waveguides to be used

as part of an optical communication system such as for example WDM. In communication

systems incorporating PLC, active devices and optical waveguides may exist as separate

entities. BRIEF DESCRIPTION OF THE DRAWINGS

[003] The subject matter regarded as the invention is particularly pointed out and

distinctly claimed in the concluding portion of the specification. The invention, however,

both as to organization and method of operation, together with objects, features, and

advantages thereof, may best be understood by reference to the following detailed

description when read with the accompanying drawings in which:

[004] Fig. 1 is a is a schematic illustration of a side-view cross section of an opto-

electric hybrid module according to some embodiments of the present invention;

[005] Fig. 2 is a schematic illustration of a top view of an opto-electric hybrid module

according to some embodiments of the present invention;

[006] Fig. 3 depicts a flowchart illustrating a method for manufacturing an opto-

electric hybrid module according to some embodiments of the present invention; and [007] Fig. 4 is a schematic illustration of a partial wafer map of a plurality of opto-

electric modules according to some embodiments of the present invention.

[008] It will be appreciated that for simplicity and clarity of illustration, elements

shown in the figures have not necessarily been drawn to scale. For example, the

dimensions of some of the elements may be exaggerated relative to other elements for

clarity. Further, where considered appropriate, reference numerals may be repeated among

the figures to indicate corresponding or analogous elements. DETAILED DESCRIPTION OF THE PRESENT INVENTION

[009] In the following detailed description, numerous specific details are set forth in

order to provide a thorough understanding of the invention. However, it will be understood

by those skilled in the art that the present invention may be practiced without these specific

details. In other instances, well-known methods, procedures, and components have not

been described in detail so as not to obscure the present invention.

[0010] It may be desirable to use a transparent substrate, such as for example glass,

both for embedding a waveguide and for serving as a support substrate for several electro-

optical components and for electrical conduits. The electro-optical components may

include for example an optical diode, photodiode, laser diode, or similar component. Such

transparent substrate may provide for direct optical coupling between the waveguide and

the electro-optical components. Reference is made to Fig. 1. A fiber optic communication

system may typically include an opto-electric hybrid module 100 that may typically be

mounted onto a printed circuit board (PCB) 105, 106. An embodiment of the opto-electric

hybrid module 100 may include an electro-optical component 110, an electronic

component 115, at least an embedded waveguide 120, an optically transparent support such

as for example glass support 125, and an optical fiber plug 130. The electro-optical

component 110 may serve as a transmitter or receiver. The electronic component 115 may

typically amplify and transfer an electric signal to an external component such as for

example an electro-optical component 110. A planar lightwave circuit (PLC) 135 may be

implemented using several waveguide manufacturing technologies such as for example a

technique used to create ion exchange in glass substrate to create waveguides 120, or. other

similar techniques that may provide an opto-electronic signal communication path embedded within a substrate 135. A printed circuit board may be included on several of a

plurality of surfaces included in the opto-electric hybrid module 100, 200 such as for

example on an outer surface 106 or an inner surface 105. Waveguides 120 may be single

mode or multimode waveguides for propagating an opto-electronic signal communication

such as for example a light beam along the substrate 135. The optical waveguide may

include optical functions such as for example optical power splitting, wavelength

multiplexing, and wavelength demultiplexing. The waveguide may be tapered to improve

the connection between the electro-optical component 110 and the waveguide 120. The

glass support 135 may typically encapsule the waveguide 120. The opto-electric hybrid

module 100, 200 may also include an optical fiber plug 130 for direct and easy connection

to an external optical fiber. In another embodiment, the external optical fiber may be

permanently connected to the optical input or output of the opto-electric hybrid module

100, 200 through bonding or similar methods for permanent optical connection.

[0011] The electronic component 115 may channel electrical energy to and from the

electro-optical component 110. The electro-optical component 110 may be for example a

photo diode, a laser diode, or similar component. An electrical interconnection such as for

example bus structures (not shown), contacts to the PCB 140, and conducting vias 145

may typically be located on the surface of the waveguide support glass 135. Such electrical

interconnects may be in the form of co-planar or strip-line conductors to allow for

improved RF performance. Shortened conducting lines may further improve RF

performance. The electrical interconnection may provide electrical power to the electronic

component 115. The electro-optical 110 and electronic 115 components may be enclosed

in a heat sink encapsulation 150 with a metal cap 155. [0012] Further reference is made to Fig. 2. According to a preferred embodiment of the

present invention the electro-optical components 110 (Fig. 1) may include for example a

laser diode 205, photodiode 210, semiconductor device (not shown) or similar electro-

optical component. The photodiode 210, for example, may be coupled to the electronic

component 115 and attached to the waveguide 120 channel through an embedded folding

micro-mirror 160. The laser diode 205, for example, may also be attached to the

waveguide 120 channel through another embedded folding micro-mirror 160. The folding

micro-mirror 160 may be strategically positioned so as to direct energy transfer between

the electro-optical component 110, such as for example the laser diode 205, and the

waveguide 120. The micro-mirror 160 may be for example a groove in the glass that

implements the Total Internal Reflection (TIR) Phenomenon or a metal-coated surface that

reflects light, or the like. The laser diode 205 for example, may typically transmit optical

energy into the waveguide 120 through the folding micro-mirror 160 while the photodiode

210, for example, may receive optical energy from the waveguide 120 through the folding

micro-mirror 160. The laser diode 205 may receive electrical energy from the electrical interface 215 and convert the electrical energy into optical energy. The photo detector such

as for example a photodiode 210 may receive optical energy from the waveguide 120 and

convert the optical energy into an electrical signal. The electrical signal may be received

and then transmitted by the electrical interface 215 to at least another electrical circuit 105,

106 that may be located on several surfaces comprising the opto-electric hybrid module

100, 200. The electrical circuits may include electrical components such as for example

digital or analog amplifiers. The electrical components may be embedded within the opto-

electric hybrid module 100, 200. [0013] The waveguide glass support 135 may typically include a plurality of ion-

exchange waveguides 120 or any similar embedded waveguides, electrical circuits 215 and

interconnects, and a plurality of beam folders such as for example the folding micro-mirror

160. The electro-optical component 110 may typically be a separate entity. Since the two

separate entities, the electro-optical component 110 and waveguide glass support 135, may

mechanically be tightly secured together their positioning for packaging may be relatively

easy and the bonding accuracy may typically lead to the improvement of the overall optical performance. The waveguide glass support 135 and the electro-optical component 110

may typically be attached or bonded with an adhesive substance. The adhesive substance

may typically be of light transmitting characteristics similar to those of the material of

support 135, thereby assuring the existence of a well matched optical path between electro-

optical component 110 and waveguide 120 while minimizing and even fully eliminating

the existence of free-space gaps in that path. The emission or admission of optical energy

by the electro-optical component 110 remains unaffected since free space or a change in

impedance may be non-existent along the optical path. Thus, complicated optical matching

considerations such as lenses and mechanical securing considerations to ensure steady and

uniform positioning of electro-optical component 110 relative to waveguide 120 may be

omitted. The adhesive mounting of the electro-optical component 110 onto the waveguide

120 may be known as bare chip mounting. Bare chip mounting may typically allow for the

development of a more compact, lightweight, optically accurate and mechanically durable

electro-optical hybrid module 100, 200 design than would be possible with a package

mounting.

[0014] A further use of the opto-electric hybrid module 100, 200 may allow for

electrical and optical coupling between one or more integrated circuits, opto-electric hybrid modules 100, 200, or electro-optical components and a printed circuit board (PCB) 105,

106, may include a plurality of waveguide structures in addition to electrical connections.

Such an opto-electric hybrid module 100, 200 may include an optical element flip-chip

mounted on a substrate 135, an optical waveguide 120 formed in the substrate 135 and

optically connected to the opto-electric component 110, and adhesives that may typically

fill the gap between the substrate 135 and opto-electric component 110. The opto-electric

component 110 may be flip-chip bonded to an integrated circuit using solder bump technology while the integrated circuit may be flip-chip bonded to a Ball Grid Array

(BGA) package. The BGA package may be bonded to the PCB 135 using for example

solder reflow technology. The opto-electric component 110 may have an attached lens to

facilitate optical coupling to the optical waveguide 120.

[0015] According to a preferred embodiment of the invention, the electronic

components 115 may be additionally mounted onto the surface of the optical waveguide

120. The electro-optical component 110 and the electronic components 115 may be

completely sealed with a resin. Since the electro-optical 110 and electronic 115

components are mounted on the surface of the optical waveguide glass support 135, the interconnection between the elements may be shortened. The interconnection may be of a

single layer, thereby facilitating the formation of the interconnection. The electro-optical hybrid module 100, 200 may be strengthened due to the resin seal (not shown) of the

electro-optical 110 and electronic 115 components. Moreover, the electro-optical module

100, 200 may improve its degree of integration by having a hybrid combination of opto-

electric 110 and electronic 115 components while simultaneously reducing cost.

[0016] Furthermore, the resin may have light blocking characteristics. The electronic

element 115 may undergo faulty operation in the event that light impinges upon it. Therefore, faulty electronic operation relating to impingement of light may be prevented by

sealing the electronic element 115 with such a resin. The electronic element 115 may have

the ability to drive the electro-optical component 110 such as for example the photodiode

210. This may lead to a greater degree of integration for the optical module 100, 200. Due

to the dual mounting of the electro-optical component 110 and the electronic element 115

that may drive or control the electro-optical component 110, the opto-electric hybrid

module 100, 200 may be of increased value such as for example an increased usage of space while achieving a lowered cost.

[0017] According to an embodiment of the present invention, a circuit 220 may be

directly laminated on the glass surface of the waveguide substrate 135, thereby eliminating

the need for a mounted electronic element 115. There may be no need to consider the

reliability of the connection between different components. The connection between

integrated circuit components may be eliminated, thereby improving the interconnection

impedance and noise characteristics while minimizing time delays. This embodiment of the invention may further lead to a higher degree of integration on the opto-electric hybrid

module 100, 200 while achieving/maintaining minimal costs.

[0018] A method as shown in Fig. 3, for manufacturing an opto-electric hybrid module

100,200 according to some embodiments of the invention may include fabricating the

waveguide glass wafer including electrical circuitry 105, 106 (block 300). Fabricating the

waveguide glass wafer may comprise creating waveguides 120 using ion exchange

technology in a Planar Lightwave Circuit (PLC) glass layer 135, printing electric lines 105

and contacts on the PLC glass layer 135, dicing a slot for example at 45 degrees, and

coating the slot with a metal according to some embodiments. A support glass wafer 125

may be produced by dicing cavities for the inclusion of opto-electrical 110 and electronic 115 components in them, creating vias 145, coating the vias with conductive material, and

printing electrical lines and contacts on both sides of the wafer (block 305). The vias 145

may be created through various etching techniques such as for example dry or wet etch.

The support glass wafer 125 may then be attached to the waveguide (PLC) glass wafer 135

thereby creating an opto-electric module 100, 200 (block 310). Reference is made to Fig.

4, which depicts a partial wafer map 400 of a plurality of opto-electric modules 100, 200

upon double bar dicing 405. The wafer may be diced at the fiber optic connector side 130

in order to create double bars 405 that expose the fiber optic endpoints 130 of the plurality

of opto-electric modules 100, 200. Prior to chip level dicing of the double bars 405, fiber

optic testing equipment may be connected to the optical fiber endpoints 130 in order to test

the yield of the opto-electric hybrid modules 100, 200. The fiber optic connector side 130

may typically be polished for example at an 8-degree angle. Pig-tail fibers may be attached

at the end of the waveguide or waveguides 120. Completing the manufacturing of some

embodiments of the present invention may include attaching the opto-electric components 110 such as for example photodiodes, laser diodes, or similar components to the opto-

electric hybrid module 100, 200 (block 315). Active alignment beam may be needed to assure alignment of the opto-electric components 110 with the waveguides 120 embedded

in the opto-electric hybrid module 100, 200. The opto-electric components 110 may

typically be encapsulated with a thermal conductive polymer. The double bars may be

diced to create separate opto-electric hybrid modules 100, 200.

[0019] While certain features of the invention have been illustrated and described

herein, many modifications, substitutions, changes, and equivalents will now occur to

those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the

invention.

Claims

CLAIMS[0020] What is claimed is:

1. A hybrid module comprising: an electro-optical component for transmitting or receiving energy; an electronic component for amplifying and transferring an electric signal to an external component; a planar light wave circuit for providing an opto-electronic signal communication path; and at least one optical waveguide embedded in said planar light wave circuit for propagating said opto-electronic signal communication;

2. A system as in claim 1, further comprising an optical fiber plug or connector.

3. A system as in claim 1, further comprising an embedded folding micro-mirror for directing energy transfer between said electro-optical component and said at least one optical waveguide.

4. A system as in claim 1 , wherein said waveguide comprises a tapering.

5. A system as in claim 1, wherein said electro-optical component and said electronic component are enclosed in a heat sink encapsulation.

6. A system as in claim 5, wherein said heat sink encapsulation comprises a metal cap.

7. A system as in claim 5, wherein said electro-optical component is coupled to said electronic component.

8. A system as in claim 5, wherein said electro-optical component is coupled to said plurality of waveguides through said embedded folding micro-mirror.

9. A system as in claim 5, wherein said electro-optical component comprises a current amplifier for amplifying weak signals.

10. A method comprising: fabricating a waveguide glass wafer; producing a support glass wafer; creating an optical chip by attaching said support glass wafer to said waveguide support glass; and creating an electro-optical module by attaching electro-optical components to said optical chip.

11. A method as in claim 10, wherein said fabricating said waveguide glass wafer further comprises: creating a plurality of waveguides using ion exchange technology in a planar lightwave circuit; printing electric lines and contacts on said planar lightwave circuit layer; dicing a slot in said planar lightwave circuit layer; and filling said slot in said planar lightwave circuit layer with a metal.

12. A method as in claim 10, wherein said producing said support glass further comprises: creating a plurality of vias; coating said vias with a conductive material; and printing electrical lines and contacts on both sides of said waveguide glass wafer.

13. A method as in claim 12, wherein said creating said plurality of vias comprises wet or dry etching.

14. A method as in claim 10, wherein said creating said optical chip further comprises:

Dicing said waveguide glass wafer at a fiber optic connector side to create double bars;

Polishing said fiber optic connector side; and Attaching pig-tail fibers at end of said plurality of waveguides.

15. A method as in claim 10, wherein said attaching said electro-optical components to said optical chip comprises using active alignment beam. 6. A method as in claim 10, wherein said creating said electro-optical module further comprises:

Encapsulating said electro-optical components and electronic components with a thermal conductive polymer; and Dicing said double bars to create separate said electro-optical modules.