U.S. patent application number 16/108803 was filed with the patent office on 2018-12-27 for wafer-level integrated opto-electronic module.
The applicant listed for this patent is CORNING OPTICAL COMMUNICATIONS LLC. Invention is credited to Ian Armour McKay, James Gavon Renfro, JR., Rebecca Kayla Schaevitz, Michael John Yadlowsky.
Application Number | 20180372968 16/108803 |
Document ID | / |
Family ID | 53762059 |
Filed Date | 2018-12-27 |
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United States Patent
Application |
20180372968 |
Kind Code |
A1 |
McKay; Ian Armour ; et
al. |
December 27, 2018 |
WAFER-LEVEL INTEGRATED OPTO-ELECTRONIC MODULE
Abstract
A method to manufacture optoelectronic modules comprises a step
of providing a first wafer comprising a plurality of first module
portions, wherein each of the first module portions comprises at
least one passive optical component, providing a second wafer
comprising a plurality of second module portions, wherein each of
the second module portions comprises at least one optoelectronic
component. The wafers are disposed on each other to provide a wafer
stack that is diced into individual optoelectronic modules
respectively comprising one of the first and the second and the
third module portions.
Inventors: |
McKay; Ian Armour; (Mountain
View, CA) ; Renfro, JR.; James Gavon; (Pacifica,
CA) ; Schaevitz; Rebecca Kayla; (Sunnyvale, CA)
; Yadlowsky; Michael John; (Sunnyvale, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CORNING OPTICAL COMMUNICATIONS LLC |
Hickory |
NC |
US |
|
|
Family ID: |
53762059 |
Appl. No.: |
16/108803 |
Filed: |
August 22, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15216136 |
Jul 21, 2016 |
10082633 |
|
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16108803 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/4239 20130101;
H01S 5/02248 20130101; G02B 6/4204 20130101; G02B 6/4214 20130101;
G02B 6/4228 20130101; H01S 5/02252 20130101; G02B 6/4274 20130101;
H01S 5/183 20130101; G02B 6/4292 20130101; G02B 6/4231 20130101;
G02B 6/4206 20130101; G02B 6/428 20130101; G02B 6/424 20130101;
H01S 5/02284 20130101; G02B 6/12002 20130101 |
International
Class: |
G02B 6/42 20060101
G02B006/42; H01S 5/022 20060101 H01S005/022; H01S 5/183 20060101
H01S005/183; G02B 6/12 20060101 G02B006/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 29, 2015 |
EP |
15178897.3 |
Claims
1. A method to manufacture optoelectronic modules, comprising:
providing a first wafer comprising a plurality of first module
portions, wherein each of the first module portions comprises at
least one passive optical component, wherein the at least one
passive optical component has a first and a second side and is
configured to modify a beam of light such that a direction of light
coupled in the at least one passive optical component at the first
side is changed and coupled out of the at least one passive optical
component at the second side; providing a second wafer comprising a
plurality of second module portions, wherein each of the second
module portions comprises at least one optoelectronic component and
metalized via holes extending in a material of the second wafer
from a first surface of the second wafer to a second opposite
surface of the second wafer, wherein the respective at least one
optoelectronic component of the second module portions is
electrically connected to the respective metalized via holes of the
second module portions; providing a third wafer comprising a
plurality of third module portions, wherein each of the third
module portions comprises at least one electronic component;
bonding the second wafer onto the third wafer such that the
respective at least one electronic component of the third module
portions is electrically coupled to the respective at least one
optoelectronic component of the second module portions by means of
the respective metalized via holes of the second module portions;
bonding the first wafer onto the second wafer to provide a wafer
stack such that each of the first module portions is aligned to a
respective one of the second module portions so that light coupled
into the respective at least one passive optical component of the
first module portions at the first side of the respective at least
one passive optical component is coupled out at the second side of
the respective at least one passive optical component and is
directed to the respective at least one optoelectronic component of
the second module portions; and dicing the wafer stack into
individual optoelectronic modules respectively comprising one of
the first and the second and the third module portions.
2. The method of claim 1, comprising: the first wafer having a
first and a second surface being opposite to the first surface;
arranging the at least one passive optical component of each of the
first module portions on the first surface of the first wafer;
providing the second wafer with the at least one optoelectronic
component of each of the second module portions being arranged on
the first surface of the second wafer; and bonding the first wafer
onto the second wafer such that the second surface of the first
wafer is disposed on the first surface of the second wafer.
3. The method of claim 1, comprising: providing the third wafer
with respective electrical contact pads for each of the third
module portions on a first surface of the third wafer, wherein the
respective electrical contact pads are electrically coupled with
the respective at least one electronic component of the third
module portions; providing the second wafer with respective
electrical contact pads for each of the second module portions on
the second surface of the second wafer, wherein the respective
electrical contact pads are electrically coupled to the respective
metalized via holes of the second module portions; and bonding the
second wafer onto the third wafer such that the second surface of
the second wafer is disposed on the first surface of the third
wafer and the respective electrical contact pads of the third
module portions are aligned to the respective electrical contact
pads of the second module portions to provide an electrical
connection between the respective electrical contact pads of the
third module portions and the respective electrical contact pads of
the second module portions.
4. The method of claim 1, comprising: providing the first wafer
with respective metalized via holes for each of the first module
portions in a material of the first wafer, the respective metalized
via holes extending from the first surface of the first wafer to
the second surface of the first wafer; providing the second wafer
with respective electrical contact pads for each of the second
module portions on the first surface of the second wafer such that
the respective electrical contact pads of the second module
portions are electrically connected to the respective metalized via
holes of the second module portions; and bonding the first wafer
onto the second wafer such that the respective electrical contact
pads of the second module portions are electrically connected to
the respective metalized via holes of the first module
portions.
5. The method of claim 3, comprising: providing a fourth wafer
being configured for thermal isolation between the third and the
second wafer, wherein the fourth wafer comprises metalized via
holes in a material of the fourth wafer, wherein the metalized via
holes are arranged to electrically couple the respective electrical
contact pads of the third module portions to the respective
electrical contact pads of the second module portions.
6. A method to manufacture optoelectronic modules, comprising:
providing a first wafer comprising a plurality of first module
portions, wherein the first wafer has a first and an opposite
second surface; providing a second wafer comprising a plurality of
second module portions, wherein the second wafer has a first and an
opposite second surface, wherein each of the second module portions
comprises at least one optoelectronic component; disposing the
first wafer onto the second wafer to provide a wafer stack such
that the second surface of the first wafer is placed opposite to
the first surface of the second wafer and each of the first module
portions is aligned to a respective one of the second module
portions so that light coupled in a respective one of the first
module portions is transferred to a respective one of the second
module portions and is directed to the respective at least one
optoelectronic component of the second module portions; and dicing
the wafer stack into individual optoelectronic modules respectively
comprising one of the first and the second module portions.
7. The method of claim 6, wherein each of the first module portions
comprises at least a fixture to old an optical fiber; and wherein
the at least one fixture is made by a wafer scale process molding
directly onto the first wafer and/or using one of a single wafer
with molded elements and several stacked waters with varying holes
and/or cut outs.
8. The method of claim 7, comprising: providing at least one of the
first and second module portions with at least one passive optical
component; and disposing the first wafer onto the second wafer to
provide a wafer stack such that each of the first module portions
is aligned to a respective one of the second module portions so
that light coupled out of the optical fiber held in the respective
at least one fixture of the first module portions is coupled into
the respective at least one passive optical component of one of the
first and second module portions at the first side of the
respective at least one passive optical component and is coupled
out at the second side of the respective at least one optical
component and is directed to the respective at least one
optoelectronic component of the second module portions.
9. An optoelectronic module, comprising: a first substrate
comprising a first module portion, wherein the first substrate has
a first and an opposite second surface; a second substrate
comprising a second module portion, wherein the second substrate
has a first and an opposite second surface, wherein the second
module portion comprises at least one optoelectronic component;
wherein the first substrate is disposed onto the second substrate
to provide the optoelectronic module such that the second surface
of the first substrate is placed opposite to the first surface of
the second substrate and the first module portion is aligned to the
second module portion so that light coupled in the first module
portion is transferred to the second module portion and is directed
to the at least one optoelectronic component of the second module
portion.
10. The optoelectronic module of claim 9, wherein the first module
portion comprises at least one fixture to hold an optical fiber,
wherein the at least one fixture is disposed on the first surface
of the first substrate.
11. The optoelectronic module of claim 10, wherein at least one of
the first and second module portion is provided with at least one
passive optical component; and wherein the first substrate is
disposed on the second substrate to provide the optoelectronic
module such that the first module portion is aligned to the second
module portion so that light coupled out of the optical fiber held
in the at least one fixture of the first module portion is coupled
into the at least one passive optical component of one of the first
and second module portions at the first side of the at least one
passive optical component and is coupled out at the second side of
the at least one optical component and is directed to the at least
one optoelectronic component of the second module portion.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 15/216,136, filed on Jul. 21, 2016, which claims the benefit of
priority to European Application No. 15178897.3, filed on Jul. 29,
2015, both applications being incorporated herein by reference.
FIELD
[0002] The disclosure is directed to a method to manufacture
optoelectronic modules. The disclosure is further directed to an
optoelectronic module.
BACKGROUND
[0003] The capability to provide sub-micrometer to few micrometer
optical alignment accuracy has been a costly and time-consuming
necessity in most optical communication components and devices
because of the small dimensions of typical optical waveguides. As
an example, in an active optical cable, PDs (Photodiodes) and
multi-mode VCSELs (Vertical Cavity Surface Emitting Lasers) are
placed individually within about 10-micrometer accuracy onto a
populated PCB (Printed Circuit Board) with electronic components.
This populated PCB is then moved to a different machine for
wirebonding and once again back to the precision placement machine
to place an optical element with lenses and a turning mirror.
Fibers are brought onto the optical element on the PCB to complete
the link to the optoelectronic module.
[0004] If any failures occur in this process, such as damaging a
VCSEL or poor placement accuracy, the entire PCB is lost. This loss
is expensive given the PCB must be pre-populated with all the
electronics through the dirty surface mount technology (SMT)
process prior to the final clean optical assembly described above.
Additionally, each placement of PDs, VCSELs and a lens block has a
tolerance of about 10 nm and thus creates a stack up allocation,
i.e. the placement tolerances accumulate, for a larger error
distribution in placement, which becomes especially problematic at
higher data rates above 10 Gbps.
[0005] As a second example, silicon photonics structures use single
mode operation, which must couple into a single mode fiber with
apertures typically less than 10 .mu.m. Consequently, alignment
accuracies need to be within just a few micrometers, e.g. 2-1
.mu.m, or better, to get reasonable optical coupling. The use of
pick and place tooling, while capable of achieving these alignment
accuracies, takes a significant amount of time and thus increases
cost of the overall system.
[0006] It is a desire to provide a method to manufacture
optoelectronic modules, wherein alignment tolerances between a
respective optical fiber coupled to the optoelectronic modules, a
respective at least one passive optical component and a respective
at least one optoelectronic components of the modules, are reduced
and wherein a large amount of the optoelectronic modules can be
manufactured in a small amount of time. A further need is to
provide an optoelectronic module, wherein alignment tolerances
between an optical fiber coupled to the optoelectronic module, at
least one passive optical component and at least one optoelectronic
component of the module are reduced and wherein the optoelectronic
module can be manufactured in a low time.
SUMMARY
[0007] According to an embodiment of a method to manufacture
optoelectronic modules, a first wafer comprising a plurality of
first module portions is provided, wherein each of the first module
portions comprises at least one passive optical component, wherein
the at least one passive optical component has a first and a second
side and is configured to modify a beam of light such that a
direction of light coupled in the at least one passive optical
component at the first side is changed and coupled out of the at
least one passive optical component at the second side.
Furthermore, a second wafer comprising a plurality of second module
portions is provided, wherein each of the second module portions
comprises at least one optoelectronic component and metalized via
holes extending in a material of the second wafer from a first
surface of the second wafer to a second opposite surface of the
second wafer, and wherein the respective at least one
optoelectronic component of the second module portions is
electrically connected to the respective metalized via holes of the
second module portions. A third water comprising a plurality of
third module portions is provided, wherein each of the third module
portions comprises at least one electronic component.
[0008] The second wafer is bonded onto the third wafer such that
the respective at least one electronic component of the third
module portions is electrically coupled to the respective at least
one optoelectronic component of the second module portions by means
of the respective metalized via holes of the second module
portions. Furthermore, the first wafer is bonded onto the second
wafer to provide a wafer stack such that each of the first module
portions is aligned to a respective one of the second module
portions so that light coupled into the respective at least one
passive optical component of the first module portions at the first
side of the respective at least one passive optical component is
coupled out at the second side of the respective at least one
optical component and is directed to the respective at least one
optoelectronic component of the second module portions.
[0009] The wafer stack is diced into individual optoelectronic
modules respectively comprising one of the first and the second and
the third module portions.
[0010] An embodiment of an optoelectronic module being manufactured
by means of the method comprises a first substrate comprising a
first module portion of the optoelectronic module including at
least one passive optical component. The module comprises a second
substrate comprising a second module portion of the optoelectronic
module including at least one optoelectronic component.
Furthermore, the module comprises a third substrate comprising a
third module portion of the optoelectronic module, wherein the
third module portion comprises at least one electronic
component.
[0011] The first substrate has a first surface and a second
opposite surface, wherein the at least one optical component is
arranged on the first surface of the first substrate. The at least
one passive optical component has a first and a second side and is
configured to modify a beam of light such that a direction of light
coupled in the at least one optical component at the first side is
changed and coupled out of the at least one passive optical
component at the second side.
[0012] The second substrate has a first surface and an opposite
second surface, wherein the at least one optoelectronic component
is arranged on the first surface of the second substrate. The
second substrate comprises metalized via holes extending in a
material of the second substrate from the first surface of the
second substrate to the second surface of the second substrate. The
at least one optoelectronic component is electrically connected to
the metalized via holes.
[0013] The second substrate is bonded onto the third substrate such
that the at least one electronic component of the third module
portion is electrically coupled to the at least one optoelectronic
component of the second substrate by the metalized via holes of the
second substrate. The first substrate is bonded onto the second
substrate such that the first module portion is aligned to the
second module portion so that light coupled into the respective at
least one passive optical component of the first module portion at
the first side of the at least one optical component is coupled out
at the second side of the at least one optical component and is
directed to the at least one optoelectronic component of the second
module portion.
[0014] The method allows to provide a plurality of optoelectronic
modules, wherein the alignment tolerances between the respective at
least one optoelectronic device, for example a photodiode, a laser
or a silicon photonics chip, and the respective at least one
passive optical component, and an optical fiber coupled to the
respective optoelectronic module are in a range of a few
micrometers, for example in a range of about 1-2 .mu.m. Thus, it is
possible to reduce fallout, cost and time of assembly of such
modules and final PCBs. The method uses wafer-scale alignment and
may further use wafer-scale testing while also making the final
module SMT compatible.
[0015] The wafer-scale technique allows manufacturers to achieve
the low alignment tolerances across hundreds to thousands of
devices simultaneously, thus reducing overall cost and time. By
also making it wafer-scale testable prior to assembly, fallout of
the final assembled device on the PCB can be reduced. The modules
may be designed to be compatible with typical semiconductor
manufacturing processes, such as SMT, so that the optoelectronic
module manufactured by the above-specified method can be integrated
into a final product without added assembly cost. The method to
manufacture the optoelectronic modules can be used for active
optical cables, silicon photonics and optical fiber connections or
potentially free-space connectivity across many industries.
Additionally, the manufacturing method would enable the large
volume that may ensue due to the wafer-scale design, low cost and
ease of assembly. Lastly, the manufacturing tolerances provided
could lend itself to making a low-cost, robust module capable of
speeds much greater than 10 Gbps and thus provide a path toward
innovation requiring high data rate communication.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows an embodiment of a method to manufacture
optoelectronic modules;
[0017] FIG. 2A shows several wafers to be stacked for manufacturing
a plurality of optoelectronic modules;
[0018] FIG. 2B shows an embodiment of stacked wafers for
manufacturing a plurality of optoelectronic modules;
[0019] FIG. 3 shows an embodiment of optoelectronic modules of
three substrates;
[0020] FIG. 4 shows a perspective view of a cutout of stacked
wafers for manufacturing a plurality of optoelectronic modules;
[0021] FIG. 5 shows an embodiment of stacked wafers for
manufacturing a plurality of optoelectronic modules;
[0022] FIG. 6 shows an embodiment of stacked wafers for
manufacturing a plurality of optoelectronic modules;
[0023] FIG. 7 shows an embodiment of stacked wafers for
manufacturing a plurality of optoelectronic modules;
[0024] FIG. 8A shows a perpendicular attachment of an embodiment of
an optoelectronic module onto an electronic board;
[0025] FIG. 8B shows a perpendicular attachment of an embodiment of
an optoelectronic module onto an electronic board;
[0026] FIG. 9A shows a downward attachment of an embodiment of an
optoelectronic module onto an electronic board;
[0027] FIG. 9B shows a downward attachment of an embodiment of an
optoelectronic module onto an electronic board;
[0028] FIG. 10A shows a vertical attachment of an embodiment of an
optoelectronic module onto an electronic board;
[0029] FIG. 10B shows a vertical attachment of an embodiment of an
optoelectronic module onto an electronic board;
[0030] FIG. 11A shows a downward attachment of an embodiment of an
optoelectronic module onto an opto-electronic board with an
embedded waveguide;
[0031] FIG. 11B shows a downward attachment of an embodiment of an
optoelectronic module onto an opto-electronic board with an
embedded waveguide;
[0032] FIG. 12A shows an embodiment of a downward arrangement of an
optoelectronic module onto an electronic board;
[0033] FIG. 12B shows an embodiment of a downward arrangement of an
optoelectronic module onto an electronic board;
[0034] FIG. 12C shows an embodiment of a downward arrangement of an
optoelectronic module onto an electronic board;
[0035] FIG. 13A shows an embodiment of several stacked wafers for
manufacturing a plurality of optoelectronic modules;
[0036] FIG. 13B shows an embodiment of several stacked wafers for
manufacturing a plurality of optoelectronic modules;
[0037] FIG. 14 shows an exploded view of several layers of an
optoelectronic module;
[0038] FIG. 15A shows an embodiment of several substrates to be
stacked above each other for manufacturing an optoelectronic
module;
[0039] FIG. 15B shows an embodiment of stacked substrates of an
optoelectronic module;
[0040] FIG. 16A shows an embodiment of stacked substrates of an
optoelectronic module;
[0041] FIG. 16B shows an embodiment of stacked substrates of an
optoelectronic module;
[0042] FIG. 17A shows an embodiment of several substrates to be
stacked above each other for manufacturing an optoelectronic
module;
[0043] FIG. 17B shows an embodiment of stacked substrates of an
optoelectronic module;
[0044] FIG. 18A shows an embodiment of stacked substrates of an
optoelectronic module;
[0045] FIG. 18B shows an embodiment of stacked substrates of an
optoelectronic module;
[0046] FIG. 18C shows an embodiment of stacked substrates of an
optoelectronic module; and
[0047] FIG. 19 shows an embodiment of stacked substrates of an
optoelectronic module.
DETAILED DESCRIPTION
[0048] The method to manufacture optoelectronic modules will now be
described in more detail hereinafter with reference to the
accompanying drawings showing different embodiments of the method.
The method may, however, be embodied in many different forms and
should not be construed as limited to the embodiments set forth
herein; rather, these embodiments are provided so that the
disclosure will fully convey the scope of the method to those
skilled in the art. The drawings are not necessarily drawn to scale
but are configured to clearly illustrate the method. The written
text included in some of the Figures should facilitate the
understanding of the Figures and particularly indicates examples of
materials which may be used for the different components,
substrates and layers but does not limit the possible materials
that can be used for these components, substrates and layers to the
materials specified in the Figures.
[0049] FIG. 1 shows steps A to F of a method to simultaneously
manufacture a plurality of optoelectronic modules. The method is
based on providing a wafer stack of several wafers 100, 200 and
300, wherein each of the waters comprises respective different
components of the optoelectronic modules. The wafer stack is diced
into the individual optoelectronic modules. FIG. 2A illustrates
respective embodiments of a first wafer 100, a second wafer 200 and
a third wafer 300 to be stacked to each other. FIG. 2B shows the
wafer stack of the bonded first wafer 100, the second wafer 200 and
the third wafer 300.
[0050] According to a step A of the method to manufacture the
optoelectronic modules, the first wafer 100 comprising a plurality
of first module portions 101 is provided. Each of the first module
portions 101 comprises at least one passive optical component 110.
The at least one passive optical component 110 has a first and a
second side and is configured to modify a beam of light such that a
direction of the light coupled in the at least one passive optical
component 110 at the first side is changed and coupled out of the
at least one passive optical component 110 at the second side.
[0051] At least one optical fiber can be aligned to the at least
one passive optical component 110 so that light may be coupled from
the at least one optical fiber into the at least one passive
optical component 110 or coupled out of the at least one passive
optical component 110 into the at least one optical fiber. Optical
fiber alignment components such as fixtures to hold and align an
optical fiber can be mounted on the first wafer 100. According to
another embodiment, the fiber alignment components can be
configured as wafers stacked on top of the first wafer 100.
[0052] According to a subsequent step B, the second wafer 200
comprising a plurality of second module portions 201 is provided.
Each of the second module portions 201 comprises at least one
optoelectronic component 210 and metalized via holes 220 extending
in a material of the second wafer 200 from a first surface S200a of
the second wafer to a second opposite surface S200b of the second
wafer. The respective at least one optoelectronic component 210 of
the second module portions 201 is electrically connected to the
respective metalized via holes 220 of the second module portions
201.
[0053] According to a subsequent step C, the third wafer 300
comprising a plurality of third module portions 301 is provided.
Each of the third module portions comprises at least one electronic
component 310.
[0054] According to a subsequent step D, the second wafer 200 is
bonded onto the third wafer 300 such that the respective at least
one electronic component 310 of the third module portions 301 is
electrically coupled to the respective at least one optoelectronic
component 210 of the second module portions 201 by means of the
respective metalized via holes 220 of the second module portions
201.
[0055] According to a subsequent step E, the first wafer 100 is
bonded onto the second wafer 200 to provide a wafer stack such that
each of the first module portions 101 is aligned to a respective
one of the second module portions 201 so that light coupled into
the respective at least one passive optical component 110 of the
first module portions 101 at the first side of the respective at
least one passive optical component 110 is coupled out at the
second side of the respective at least one optical component 110
and is directed to the respective at least one optoelectronic
component 210 of the second module portions 201.
[0056] According to a subsequent step F, the wafer stack comprising
the first wafer 100, the second wafer 200, and the third wafer 300
is diced into individual dies respectively comprising one of the
first and the second and the third module portions 101, 201 and 301
for respectively forming one of the optoelectronic modules. Each of
the optoelectronic modules is formed by a respective first module
portion 101 of the first wafer 100, a respective second module
portion 201 of the second wafer 200 and a respective third module
portion 301 of the third wafer 300, wherein the respective first,
second and third module portions are stacked and bonded above each
other.
[0057] The first wafer 100 is provided in the step A with a first
surface S100a and a second surface S100b being opposite to the
first surface S100a. The respective at least one passive optical
component 110 of each of the first module portions 101 is arranged
on the first surface S100a of the first wafer 100. The second wafer
200 is provided in step B with the respective at least one
optoelectronic component 210 of each of the second module portions
200 being arranged on the first surface S200a of the second wafer
200. According to an embodiment of method step C, the first wafer
100 is bonded onto the second wafer 200 such that the second
surface S100b of the first wafer 100 is disposed on the first
surface S200a of the second wafer 200.
[0058] FIG. 3 shows several optoelectronic modules 1 after being
diced out of the wafer stack comprising the first wafer 100, the
second wafer 200 and the third wafer 300. Each of the
optoelectronic modules 1 comprises a first substrate 100' being cut
out of the first wafer 100 of the wafer stack and comprising the
first module portion 101 of the respective optoelectronic module
including the at least one passive optical component 110.
Furthermore, each of the optoelectronic modules 1 comprise a second
substrate 200' being cut out of the second wafer 200 of the wafer
stack and comprising the second module portion 201 of the
respective optoelectronic module including the at least one
optoelectronic component 210. Each of the optoelectronic modules
further comprises a third substrate 300' being cut out of the third
wafer 300 of the wafer stack and comprising the third module
portion 301 of the optoelectronic module, wherein the third module
portion 301 comprises the at least one electronic component
310.
[0059] The first substrate 100' has a first surface and a second
opposite surface, wherein the at least one passive optical
component 110 is arranged on the first surface of the first
substrate 100. The at least one passive optical component 110 has a
first and a second side and is configured to modify a beam of light
such that a direction of the light coupled in the at least one
optical component 110 at the first side is changed and coupled out
of the at least one passive optical component 110 at the second
side.
[0060] The second substrate 200' has a first surface and an
opposite second surface, wherein the at least one optoelectronic
component 210 is arranged on the first surface of the second
substrate 200'. The second substrate 200' comprises the metalized
via holes 220 extending in a material of the second substrate 200'
from the first surface of the second substrate to the second
surface of the second substrate. The at least one optoelectronic
component 210 is electrically connected to the metalized via holes
220.
[0061] The second substrate 200' is bonded onto the third substrate
300' such that the at least one electronic component 310 of the
third module portion 301 is electrically coupled to the at least
one optoelectronic component 210 of the second module portion 201
by the metalized via holes 220 of the second substrate 200'. The
first substrate 100' is bonded onto the second substrate 200' such
that the first module portion 101 is aligned to the second module
portion 201 so that light coupled into the respective at least one
passive optical component 110 of the first module portion 101 at
the first side of the at least one optical component is coupled out
at the second side of the at least one optical component 110 and is
directed to the at least one optoelectronic component 210 of the
second module portion 201.
[0062] According to an embodiment of the method to manufacture the
optoelectronic module, the second wafer 200 may be configured as a
GaAs or a silicon photonics wafer or an InP wafer. The first wafer
100 may be configured as one of a glass wafer and an opaque polymer
wafer with holes drilled out and filled with a transparent polymer.
The respective at least one passive optical component 110 of the
first module portions 101 may comprise an optical lens and/or a
light turning element, for example an optical mirror, being
configured to change a direction of the light beam, for example by
TIR (Total Internal Reflection), so that light is coupled between
an optical fiber coupled to the respective first module portions
101 and the respective at least one passive optical component 110
of the first module portions 101.
[0063] The respective at least one optoelectronic component 210 of
the second module portions 201 may be configured as an optical
emitter, for example a VCSEL, and/or an optical receiver, for
example a photodiode. The respective at least one electronic
component 310 of the third module portions 301 may be configured as
an electrical driver and/or an electrical amplifier.
[0064] As explained above, the first opto-mechanical wafer 100 may
comprises a substrate of glass. Glass can provide a flat surface to
mold optical components, such as lenses and turning mirrors, on the
first wafer 100. Glass can also have precision features etched into
its surface and through the first wafer 100 to allow for any
mechanical alignment of optical fibers or other components.
Furthermore, glass can be designed with coefficients of thermal
expansion (CTEs) similar to semiconductor wafers, thus improving
reliability of the final optoelectronic modules over large
temperature ranges. Lastly, glass is an ideal substrate for
high-speed signal integrity and both metal traces and vias can be
made on it.
[0065] FIG. 4 shows a perspective view of an embodiment of an
optoelectronic module 1 after dicing the wafer-scale stack in
perspective view, wherein each of the first, second and third
module portions 101, 201 and 301 comprises electrical contact pads
to provide an external electrical connection to the electrical
and/or optoelectronic components of the module or to electrically
connect the electrical and optoelectronic components to each
other.
[0066] According to an embodiment of the method to manufacture the
optoelectronic modules, the second wafer 200 can be provided in
method step B with respective electrical contact pads 230 for each
of the second module portions 201. The respective electrical
contact pads 210 are electrically coupled to the respective
metalized via holes 220 of the second module portions 201. The
respective electrical contact pads 230 are arranged on the second
surface S200b of the second wafer 200.
[0067] In method step C, the third wafer 300 is provided with
respective electrical contact pads 330 for each of the third module
portions 301. The respective electrical contact pads 330 are
electrically coupled with the respective at least one electronic
component 310 of the third module portions 301. The respective
electrical contact pads 330 are arranged on a surface S300a of the
third wafer.
[0068] According to an embodiment of method step D, the second
wafer 200 is bonded onto the third wafer 300 such that the second
surface S200b of the second wafer 200 is disposed on the surface
S300a, of the third wafer 300 and the respective electrical contact
pads 330 of the third module portions 301 are aligned to the
respective electrical contact pads 230 of the second module
portions 201 to provide an electrical connection between the
respective electrical contact pads 330 of the third module portions
301 and the respective electrical contact pads 230 of the second
module portions 201.
[0069] According to an embodiment of the method to manufacture the
optoelectronic modules, the third wafer 300 is provided in method
step A with respective metalized via holes 320 for each of the
third module portions 301 in a material of the third wafer 300. The
respective metalized via holes 320 extend from the first surface
S300a of the third wafer 300 to a second opposite surface S300b of
the third wafer 300. The respective electrical contact pads 330 of
the third module portions 301 arranged on the first surface S300a
of the third wafer 300 are electrically coupled to the respective
metalized via holes 320 of the third module portions 301.
[0070] The third water 300 is provided with respective electrical
contact pads 340 for each of the third module portions 301 on the
second surface S300b of the third wafer 300. The respective
electrical contact pads 340 of the third module portions 301 on the
second surface S300b are electrically coupled to the respective
metalized via holes 320 of the third module portions 301. According
to the embodiment of the optoelectronic module 1 shown in FIG. 4,
the optoelectronic module comprises the electrical contact pads 330
and 340 being arranged on both surfaces S300a and S300b of the
wafer 300.
[0071] According to a further embodiment of the method to
manufacture the optoelectronic modules, the first wafer 100 is
provided in method step A with respective metalized via holes 120
for each of the first module portions 101 in a material of the
first wafer 100. The respective metalized via holes 120 extend from
the first surface S100a of the first wafer 100 to the second
surface S100b of the first wafer 100.
[0072] According to an embodiment of the method step B, the second
wafer 200 is provided with respective electrical contact pads 240
for each of the second module portions 201 on the first surface
S200a of the second wafer 200 such that the respective electrical
contact pads 240 of the second module portions 201 are electrically
connected to the respective metalized via holes 220 of the second
module portions 201.
[0073] According to an embodiment of the method step E, the first
wafer 100 is bonded onto the second wafer 200 such that the
respective electrical contact pads 240 of the second module
portions 201 are electrically connected to the respective metalized
via holes 120 of the first module portions 101.
[0074] According to another embodiment of the method to manufacture
the optoelectronic modules, the first wafer 100 is provided in
method step A with respective electrical contact pads 130 for each
of the first module portions 101 on the second surface S100b of the
first wafer such that the respective electrical contact pads 130 of
the first module portions 101 are electrically connected to the
respective metalized via holes 120 of the first module portions
101.
[0075] Furthermore, the first wafer 100 can be provided in method
step A with a conductive redistribution layer 150 on the second
surface S100b of the first wafer 100. The conductive redistribution
layer 150 comprises respective conductive traces for each of the
first module portions 101, wherein the respective conductive traces
of the conductive redistribution layer 150 are arranged to
electrically couple the respective contact pads 130 of the first
module portions 101 on the second surface S100b of the first wafer
100 to the respective metalized via holes 120 of the first module
portions 101.
[0076] According to the embodiment of the optoelectronic module 1
shown in FIG. 4, the first module portion 101 comprises electrical
contact pads 130 arranged on the second surface S100b of the wafer
100 and electrical contact pads 140 arranged on the first surface
S100a of the first wafer MO. The electrical contact pads 140 on the
top surface S100a of the first wafer 100 could allow for flip-chip
bonding of the optoelectronic module 1.
[0077] According to an embodiment of the method to manufacture the
optoelectronic modules, the second wafer 200 comprising the second
module portions 201 with the respective optoelectronic components
210 is configured as a wafer made of GaAs. The electrical signals
would traverse from the top surface of the third wafer 300
comprising the third module portions with the respective electronic
components through the GaAs vias 220 of the second wafer 200 to the
first wafer 100 comprising opto-mechanical components 110 to
connect the electrical signals to an external electronic board, for
example a PCB.
[0078] Additionally, the vias 220 would electrically connect the
second wafer 200 to the third wafer 300 containing either laser
drivers or receiver amplifiers as electronic components to drive
the optoelectronic components, for example the VCSELs or IUDs, of
the second wafer respectively. In this implementation, the top
first wafer 100 would have passive optical components such as
lenses and turning mirrors, as well as opto-mechanical components
for fiber attachment components and also comprises electrical
traces and vias to connect to an external board such as a PCB. In
configuring the stack up using GaAs vias, very well controlled
impedances and electrical losses capable of achieving very high
data rates are provided.
[0079] Another possible implementation utilizing via technology
would be in SiP with vias through silicon. In this implementation,
the second wafer 200 is configured as a Silicon Photonics wafer.
The electrical signals from the bottom third (electronic) wafer 300
comprising the electronic components could either traverse from the
top to the bottom of the third (electronic) wafer 300 or from the
top of the third (electronic) wafer 300 through the middle second
(SiP optoelectronic) wafer 200 to the top first (opto-mechanical)
wafer 100. The top of the electronic wafer 300 would also be
connected to the middle SiP optoelectronic wafer 200 in order to
drive the transmitter and receiver optoelectronic devices 210. In
this implementation, the top opto-mechanical wafer 100 may
optionally have electrical connectivity.
[0080] The specified method utilizes (GaAs, Si or other
wafer-based) via fabrication technology to reduce parasitics of
wirebonding optoelectronic devices for III-V wafers and in other
cases for multi-chip integration of Si-based electronic components.
For the purpose of the specified method, vias enable compact
wafer-level integration of optical sources and detectors on a
wafer, such as a GaAs or silicon photonics wafer, sandwiched
between the third (bottom) wafer 300 having electronic functions
such as laser drivers and receiver amplifiers, for example Si CMOS
or SiGe Bi-CMOS, and the first (top) wafer 100 having passive
optical components, for example lenses, turning mirrors, fiber
alignment components as well as possibly components for electrical
connectivity.
[0081] According to an embodiment of the method to manufacture the
optoelectronic modules, the wafer stack comprising the bonded
first, second and third wafer 100, 200 and 300 may be diced along
the respective metalized via holes 120 of the first module portions
101 of the first wafer 100 into the individual dies/optoelectronic
modules 1 to create half- or castellated vias in the first wafer
100. As shown for the optoelectronic module 1 of FIG. 4, vias 120
are arranged in the material of the first wafer 100 extending from
the first surface S100a to the second surface S100b of the first
wafer 100. In order to separate the optoelectronic module 1, the
first wafer 100 is diced through the metalized vias 120 such that
half- or castellated vias are created. The castellated vias could
allow for perpendicular/edge bonding of the optoelectronic module
as illustrated below in FIG. 8A.
[0082] FIG. 5 shows another embodiment of a wafer stack comprising
the first wafer 100, the second wafer 200 and the third wafer 300.
In contrast to the embodiment of the wafer stack shown in FIG. 2B,
the first wafer 100 is provided without any metalized vias through
the first wafer 100 for backside mounting. Fiber alignment
components to hold and align the optical fibers to the optical
components 110 can be mounted on the first wafer 100. According to
another embodiment, the fiber alignment components can be
configured as wafers stacked on top of the first wafer 100. After
being stacked and aligned the wafer stack is diced into individual
optoelectronic modules.
[0083] According to a possible embodiment of the method to
manufacture the optoelectronic modules 1, a fourth wafer 400
configured for thermal isolation may be provided in method step D
between the third wafer 300 and the second wafer 200, wherein the
fourth wafer 400 comprises metalized via holes in a material of the
fourth wafer, wherein the metalized via holes are arranged to
electrically couple the respective electrical contact pads 330 of
the third module portions 301 to the respective electrical contact
pads 230 of the second module portions 201. FIG. 6 shows an
embodiment of a wafer stack comprising the first wafer 100, the
second wafer 200, the third wafer 300 and the fourth wafer 400.
[0084] The fourth wafer 400 serves as to improve thermal isolation
of the second (optoelectronic) wafer 200 from the first
(electronic) wafer 300. The insertion of the fourth wafer 400 al
lows to protect the optoelectronic components 210, for example an
optical source and detector of the second wafer 200, from the
electronic components 310, for example drive electronics of the
third wafer. The fourth wafer 400 may be configured as a glass
interposer wafer with metal vias and redistribution layers between
the third and the second wafers 300 and 200. In this variation, the
wafer stack up would include a total of four wafers beginning at
the bottom with the third (electronic) wafer 300, followed by the
fourth wafer 400 acting as a thermal isolation wafer, the second
(optoelectronic) wafer 200 and, at the top, the first
(opto-mechanical) wafer 100. The isolation may especially be
important for the VCSEL sub-assembly where the output optical power
as well as the threshold current is affected significantly by
temperature especially as data rates increase, but also may be
important in SiP (Silicon Photonics) where some devices are
temperature sensitive.
[0085] FIG. 7 shows an embodiment of a wafer stack comprising just
the first wafer 100 and the second wafer 200. The first wafer 100
comprises first module portions 101 comprising at least one passive
optical component 110 and metalized via holes 120. The second wafer
200 comprises the second module portions 201 comprising at least
one optoelectronic component and metalized via holes extending in
the material of the second wafer 200. In contrast to the embodiment
of the wafer stack shown in FIG. 2B, the wafer stack does not
comprise the third wafer 300. For this embodiment, only one set of
vias are needed, either in the first wafer 100 or the second wafer
200, but not both. Vias in the first wafer 100 would allow for
downward or horizontal mounting as shown in FIGS. 8B, 9B or 11B,
while vias in the second wafer 200 would allow for mounting as
shown in FIG. 10b, 12a, 12b or 12c.
[0086] FIGS. 8A to 12C show different arrangements of an
optoelectronic module 1 on an electronic board 3. The
optoelectronic module 1 shown in FIGS. 8A, 9A, 10A and 11A.
comprises the third substrate 300' with electronic components 310,
such as drivers or amplifiers integrated in the substrate 300', the
second substrate 200' with the optoelectronic components 210, for
example photodiodes or VCSELs, and the first substrate 100' with
the passive optical components 110, such as optical lenses. The
first substrate 100' may also include electrical and/or
opto-mechanical components. The second substrate 200' contains
electrical vias 220 to electrically couple the electronic
components of the third substrate 300' with the optoelectronic
components of the second substrate. The electronic components and
the optoelectronic components may be electrically coupled to the
electronic board by means of electrical traces disposed on a
surface of the first substrate 100', as shown, for example, in the
embodiments of FIGS. 8A, 9A and 11A. In the embodiment shown in
FIG. 10A, there are no electrical contacts to the first substrate
100', but there are electrical vias in the third substrate 300' to
connect to the electronic board 3.
[0087] The optoelectronic module 1 shown in FIGS. 8B, 9B, 10B, 11B
and 12A to 12C only comprises the first substrate 100' and the
second substrate 200' but does not comprise the third substrate
300'. According to the embodiments shown in FIGS. 8B, 9B, 10B, 11B
and 12A to 12C the electronic components are provided as separate,
individual devices 30 directly mounted on the electronic board 3.
The optoelectronic module 1 is provided by dicing the wafer stack
shown in FIG. 7 into individual modules. The first substrate 100'
may or may not comprise electrical vias/metalized via holes. FIGS.
8b, 9b and 11b show embodiments with vias in the first substrate
100' connecting the second substrate 200'. The vias on the first
substrate 100' can then connect to the electronic board 3 by means
of castellated vias (FIG. 8b) or electronic contact pads (FIGS. 9b
and 11b). The electronic connection then provides electrical
connectivity between the second substrate 200' and the electronic
components 30 being mounted on the electronic board 3. FIGS. 10b
and 12A to 12C show examples where the first substrate 100' do not
comprise electrical vias/metalized via holes or any metal
redistribution layers. In the alternate embodiment, substrate 200'
comprises of electrical vias/metalized via holes in order to
connect to the electronic board 3 and, in particular, to the
electronic components 30 being mounted on the electronic board
3.
[0088] According to embodiments of an arrangement of the
optoelectronic module 1 on the electronic board 3, shown in FIGS.
8A and 8B, the optoelectronic module 1 is perpendicularly attached
onto the electronic board 3. To this purpose, the first wafer 100
may comprise castellated vias 110 as described above and shown in
FIG. 4. Metal traces 10 may be arranged on the electronic board 3
to connect the optoelectronic module 1, for example by means of the
castellated vias, to electronic components of the electronic board
2. Metallic pads, for example Cu pads, may be optionally be
provided on the backside of the electronic board 3 for solder
reflow to a master PCB, for example a motherboard. A glue 20 may be
applied to the surface of the electronic board 3 to provide any
stability for mounting the optoelectronic module 1 to the board
3.
[0089] FIGS. 9A and 9B respectively show an embodiment of an
arrangement of an optoelectronic module 1 onto an electronic board
3, for example a printed circuit board, wherein the optoelectronic
module 1 is attached downward onto the electronic board 3. Metal
traces 10 are provided on a surface of the electronic board 3 to
electrically connect the electronic components of the electronic
board 3 to the optoelectronic module 1.
[0090] FIGS. 10A and 10B respectively show an embodiment of an
arrangement of an optoelectronic module 1 onto an electronic board
3, wherein the optoelectronic module 1 is vertically mounted onto
the electronic board 3. The optoelectronic module 1 shown in FIG.
10A is provided by dicing the wafer stack shown in FIG. 5 into
individual modules. The optoelectronic module 1 shown in FIG. 10B
is provided by dicing a wafer stack only comprising the first wafer
100 and the second wafer 200, wherein the first wafer does not
comprise electrical vias. The optical fiber 2 is held and aligned
by means of an alignment component, for example, a fixture 160. The
fixture 160 may be configured as an individual component
mounted/attached on the surface of the first substrate 100' or as a
wafer/wafers with or without molded elements stacked on top of the
first substrate 100'.
[0091] FIGS. 11A and 11B respectively show an embodiment of a
downward arrangement of an optoelectronic module 1 onto an
opto-electronic board 3. Metal traces 10 are provided on a surface
of the opto-electronic board to electrically connect the electronic
components of the opto-electronic board 3 to the optoelectronic
module I. Electrical vias are provided in the first substrate 100'
to make the electrical connection between the electronic board 3
and the second substrate 200' (and the third substrate 300' for the
embodiment of FIG. 11A). The opto-electronic board 3 may comprise a
channel to insert a waveguide 4 being embedded in the
opto-electronic board 3 such that a front face of the embedded
waveguide 4 is arranged in a cavity of the opto-electronic board 3
under the passive optical component 110, for example a lens, of the
optoelectronic module. Light may be coupled from the front face of
the embedded waveguide 4 through the passive optical component 110
into the optoelectronic module 1 and vice versa. To this purpose,
the opto-electronic board 3 may comprises a mirror/TIR component to
change the direction in order to aid in the coupling of light.
[0092] FIGS. 12A to 12C show downward approaches of arrangements of
an optoelectronic module 1 comprising the first (opto-mechanical)
substrate 100' and the second (optoelectronic) substrate 200'. The
optoelectronic module 1 has no wafer-scale IC integration. The
optoelectronic module 1 has only a wafer-scale integration with the
first (opto-mechanical) wafer 100 and the second (optoelectronic)
wafer 200 and possibly with a fiber alignment component made up of
multiple wafers or molded components on a single wafer. The
optoelectronic module 1 is provided by dicing the wafer stack as
shown in FIG. 7 into individual modules. The electronic board 3 is
provided with a cutout to place the optoelectronic module 1 to
different components.
[0093] FIG. 12A shows an embodiment of an arrangement of an
optoelectronic module 1 comprising the opto-mechanical substrate
100' which can be made of glass and the optoelectronic substrate
200' on the electronic board 3. The optoelectronic module 1 is
electrically bonded onto the electronic component 30, for example a
transceiver. The optoelectronic substrate 200' is disposed onto the
electronic component 30. The optoelectronic substrate 200' contains
metallized via holes 220, i.e. electrical vias, to electrically
couple the optoelectronic components of the optoelectronic
substrate 200' to the electrical component 30. The electrical
component 30 is electrically coupled to the electronic board 3.
[0094] FIG. 12B shows another embodiment of an arrangement of an
optoelectronic module 1 comprising the opto-mechanical substrate
100' which can be made of glass and the optoelectronic substrate
200' on the electronic board 3. The optoelectronic module 1 is
bonded onto an interposer 40 along with the electronic component
30, for example a transceiver. The interposer 40 comprises
electrical vias 41 to electrically couple the optoelectronic
components of the optoelectronic substrate 200' to the electrical
component 30 and electrical vias 42 to electrically couple the
optoelectronic components and the electrical component 30 to the
electronic board 3.
[0095] FIG. 12C shows another embodiment of an arrangement of an
optoelectronic module 1 comprising the opto-mechanical substrate
100' which can be made of glass and the optoelectronic substrate
200' on the electronic board 3. The optoelectronic substrate 200'
is placed onto an electronic substrate 50, The optoelectronic
components of the optoelectronic substrate 200' are electrically
coupled to the electronic board 3 via electrical traces of the
electronic substrate 50. The electronic component 30 is mounted to
a side of the electronic board 3.
[0096] According to an embodiment of the method to manufacture the
optoelectronic modules, the first opto-mechanical wafer 100 may be
provided with mechanical elements to fix the optical fiber 2 to the
module 1 with high precision and exact alignment, thus creating a
robust and well-aligned optical link. To this purpose, in method
step A, a respective at least one fixture 160 fabricated from a
wafer with molded alignment features or a stack of wafers with
varying sized vias may be placed for each of the first module
portions 101 on the first surface S100a of the first wafer 100 to
couple a respective at least one optical fiber 2 to the first
module portions 101, as shown in FIGS. 8A to 10B and in FIGS. 12A
to 12C. The respective at least one fixture 160 is configured to
hold the respective at least one optical fiber 2 and to align the
respective at least one optical fiber 2 to the respective at least
one passive optical component 110 of the first module portions 101
such that light is coupled between the respective at least one
optical fiber 2 and the respective at least one passive optical
component 110 of the first module portions 101.
[0097] According to another embodiment of the method to manufacture
the optoelectronic components, the respective at least one fixture
160 is configured to provide a distance between a front face of the
respective at least one optical fiber 2 coupled to the first module
portions 101 and the respective at least one passive optical
component 110 of the first module portions 101.
[0098] The fixture may be made by wafer scale process molding
directly onto the first wafer and/or is one of a single wafer and
several stacked wafers with varying holes or molded elements to
form the fixture and bonded to the first wafer at the wafer
scale.
[0099] FIGS. 8A to 12C show the fixture 160 being placed on the
first surface S100a of the first module portion 101 of the
optoelectronic module 1 to hold and align the optical fiber 2 to
the passive optical component 110. The fixture 160 may comprise
protrusions 161 being configured to hold the optical fiber 2 in a
distance far away from the passive optical component 110. According
to a possible embodiment, the fixture 160 can be made of a single
wafer with molded components. According to another embodiment, the
fixture can be made of a stack of wafers with varying sized holes
and aligned to the first wafer 100 in the same fashion that the
first wafer 100 is aligned to the second wafer 200. According to
another embodiment, the fixture 160 may comprise individual fixture
elements bonded precisely to each module.
[0100] For the majority of implementations described above, metal
traces and vias on the first opto-mechanical wafer 100 are used to
connect signals to an external PCB. This concept is shown for
example in FIGS. 2A and 2B. The sub-assembly could be mounted onto
a PCB perpendicular to its surface as shown in FIGS. 8A and 8B.
[0101] Since the overall footprint of the optoelectronic modules
can be reduced by stacking the second (optoelectronic) wafer 200 on
top of the third (electronic) wafer 300 or IC, it is conceivable
this implementation could even work for applications with limited
vertical space. An example of such an application is an active
optical cable assembly in which this module would be integrated
into the board residing in the plug of the cable.
[0102] Alternatively, the vias in the first opto-mechanical wafer
100 could be designed such that the metal connections are on the
opposite side of the wafer and the module could be mounted
horizontally as shown in FIGS. 9A and 9B. In the horizontal
arrangement, the electronic board 3 would need a cutout to allow
for the optical path through the electronic board or it would need
to be an optical PCB with embedded waveguides as shown in FIGS. 9A
and 9B. By architecting the solution horizontally, it may be
possible to improve heat extraction and the electrical signaling
characteristics. Such a solution may benefit applications where
speed, power and heat are paramount, such as in data centers and
server farms.
[0103] According to another embodiment of the method to manufacture
the optoelectronic modules, a spacer layer may be provided on the
first surface S100a of the first wafer 100 to provide a distance
between a front face of the respective at least one optical fiber 2
coupled to the first module portions 101 and the respective at
least one passive optical component 110 of the first module
portions 101.
[0104] According to a further embodiment of the method to
manufacture the optoelectronic modules 1, the functionality of the
bonded respective first and second module portions 101, 201 and/or
the bonded respective third and second module portions 301, 201
and/or the bonded respective first and second and third module
portions 101, 201, 301 is tested in the method step D before dicing
the wafer stack into the individual dies. According to another
embodiment, the functionality of the optoelectronic modules is
tested before dicing the bonded first, second and third wafer in
method step E into the individual dies/optoelectronic modules.
[0105] In order to make the final optoelectronic module compatible
to SMT (Surface Mounted Technology), the respective materials of
the first, second and third wafer must be chosen appropriately and
a covering element could be needed over the optical and mechanical
alignment features to prevent debris from compromising that area.
According to a possible embodiment of the method to manufacture the
optoelectronic modules, the covering element may be placed on the
first surface S100a of the first wafer 100 to protect the
respective at least one passive optical component 110 of the first
module portions 101 from debris when dicing the wafer stack into
the individual dies and/or to assist with fiber alignment.
Alternatively a cleaning step may be used in place of a protective
cover.
[0106] The covering element could prove useful during the dicing
process of the wafer as well as during SMT. Thus, the cover should
be placed prior to singulation (at the wafer-scale) and removed
following the entire SMT process and just before fiber insertion.
Additionally, the cover could be placed back onto the module
following fiber insertion to add mechanical support and alignment
of the fiber.
[0107] The integration of the three wafers, i.e. the bottom
electrical, the middle optoelectronic and the top opto-mechanical
wafers 300, 200 and 100 provides many possible benefits. One
benefit is the compact integration of the second (optoelectronic)
wafer 200, for example GaAs VCSEL or silicon photonics wafer, with
the third (bottom electrical) wafer 300, which leads to very well
controlled impedances and parasitics critical for data rates above
10 Gbps.
[0108] A second benefit is the tight alignment accuracies and
parallelism of alignment over hundreds to thousands of modules of
the first (opto-mechanical) wafer 100 to the second
(optoelectronic) wafer 200, critical for high-speed multi-mode as
well as single-mode operation. A third benefit is the capability to
have easy access to electrical signals external to the module
either by vias through the second (optoelectronic) wafer 200
connecting the top of the third (electronic) wafer 300 to the first
(opto-mechanical) wafer 100 or alternatively vias through the third
(electronic) wafer 300 connecting the top to the bottom of the
third wafer 300.
[0109] A fourth benefit is the compact size of the entire
subassemblies after dicing the water-stack of the first, second and
third wafer. A fifth benefit is the compatibility of a final
optoelectronic module with traditional electronic processing
technologies, such as Surface Mount Technology (SMT). A sixth
benefit is that the platform can be used for both multi-mode and
single-mode optical integration given the very tight optical
alignment tolerances, allowing for use with traditional VCSEL-based
multi-mode optics as well as Silicon Photonics (SiP) single-mode
optics with all light emission is surface normal. And lastly, these
optoelectronic subassemblies have the further capability of
wafer-scale testing to produce "known-good modules".
[0110] The method to manufacture optoelectronic modules is
described in the following by process steps for manufacturing an
optoelectronic receiver module using the first opto-mechanical
wafer 100, the second optoelectronic wafer 200 and the third
electronic wafer 300, wherein a GaAs approach is assumed to be used
for the second wafer 200.
[0111] According to a first method step, the electronic wafer 300
is designed with module portions 301 respectively comprising a
receiver integrated circuit (IC) and top electrical pads having a
pitch easily fabricated on a low-cost electronic circuit substrate,
for example a PCB. An example pitch would be 0.25 mm where the pads
and spacing widths are 0.125 mm. Variation of this design is valid
presuming the electrical signal integrity is good and the
integration onto an electronic board remains feasible.
[0112] In a subsequent step the optoelectronic wafer 200 is
designed with second module portions 201 respectively comprising a
GaAs photodiode with pad locations, spacing and widths that match
the receiver IC and through GaAs vias to replicate the location,
spacing and widths of the electrical pads on the backside of the
optoelectronic GaAs wafer 200.
[0113] After fabrication of the electronic and optoelectronic
wafers, thermo-compression or other means may be applied to
electrically bond the optoelectronic GaAs wafer 200 onto the
electronic wafer 300, and align the electrical pads on the top
surface of the electronic wafer 300 to the pads on the bottom
surface of the optoelectronic GaAs wafer 200.
[0114] Some of the electrical pads on the top surface of the
optoelectronic GaAs wafer 200 need only connect to the bottom
electronic wafer 300, for example those that connect to the
photodiode, while other pads need to connect eventually to the
electronic board, for example a PCB. The layout of the pads and the
subsequent metal redistribution layer on the glass substrate should
reflect that connection requirement.
[0115] According to a subsequent step, the stacked wafers 300 and
200 are tested for optical and electrical functionality, for
example, by using an optical and electrical probe system.
[0116] The electrical portion of the opto-mechanical wafer 100 may
be designed with an electrical redistribution layer from trace pads
aligned to the optoelectronic GaAs wafer 200 top surface to
metalized vias in the glass. The vias should be designed such that
dicing would occur through the via and provide sufficient metal
remaining in the half- or castellated-via to create contacts in a
perpendicular orientation.
[0117] Alternatively, the vias could be of the non-castellated type
and flipped onto a PCB. Following the electrical design,
opto-mechanical components including polymer lenses, spacer layers,
mechanical alignment features to align optical fibers to the lenses
and provide an optimized optical path are designed. After the
design phase, the opto-mechanical wafer 100 can be fabricated by
the steps of creating through-glass vias (TGVs), metalizing glass
vias, metalizing glass redistribution layer and contact pads,
plating up metal lines and contacts as needed, molding polymer
lenses on alternate side, optionally placing a spacer layer,
optionally placing an optical turn, placing fiber alignment
features and placing mechanical fixturing features for the fiber
holder, all of which may be done at the wafer scale.
[0118] In a subsequent step thermo-compression or other means of
electrical bonding is provided to bond the top surface of
electronic/optoelectronic wafer stackup onto the metalized side of
the opto-mechanical wafer 100 so that the photodiodes are aligned
with the lenses within low tolerance, for example an accuracy of
less than 2 .mu.m. Additionally, an index matching gel can be
placed between the photodiode surface and the glass to minimize
reflections on the surfaces.
[0119] The modules may be tested on the wafer-scale before dicing,
wherein any may be marked that fail to meet manufacturing standards
for electrical and optical connectivity. After the testing, a
removable wafer-scale covering element may be placed over the
opto-mechanical features on the top surface of the opto-mechanical
wafer 100. The stacked wafers 300, 200 and 100 are then diced into
individual optoelectronic modules, cleaned and the temporary
covering element is removed.
[0120] The singularized final optoelectronic modules may be
visually tested and additionally tested in a test fixture for good
electrical and optical connectivity for perpendicular, vertical or
downward surface mounting to a PCB. Afterwards, the temporary
covering element is replaced for shipping and as a possible final
fiber alignment mechanical fixture.
[0121] One alternative process flow in which the electronic wafer
300 is not part of the optoelectronic module as shown for the wafer
stack in FIG. 7 would change a few of the steps described above.
The first step would change such that some or possibly none of the
metal pads on the IC need match the GaAs substrate of the
optoelectronic wafer. The step of bonding the electronic and the
optoelectronic wafer would be removed. According to a possible
embodiment, the steps of designing and fabricating the
opto-mechanical wafer 100 would not need any of the metallization
described. The opto-mechanical wafer could still have metallization
in some embodiments as shown in FIGS. 8B, 9B and 11B, and have it
mounted on the side or flip chipped and with the silicon IC on the
electronic board or glass interposer instead of in the stack up.
The step of bonding the opto-mechanical wafer 100 onto the
optoelectronic wafer 200 could only need index matching epoxy and
no electrical connection according to a possible embodiment. After
the step of testing the optoelectronic module and replacing the
temporary cover, an additional step is needed to apply
thereto-compression, or by other means, mount the optoelectronic
module onto an electronic wafer for good electrical connection.
[0122] Alternatively, the last step could be to mount the
optoelectronic module onto a glass interposer with the electronic
chip mounted to the backside or to the side for thermal isolation
or to a common substrate, such as a PCB. The final module would
then be tested for electrical and optical performance. These
possible embodiments are represented in FIGS. 12A to 12C.
[0123] Alternatively, the last step could be to mount the
optoelectronic module to the final electronic board 3 with the
electronic chip mounted to the side as shown in FIGS. 8B, 9B, 10B
and 11B.
[0124] For the silicon photonics process, the same steps above
could be used with the GaAs wafer 200 replaced by a silicon
photonics wafer 200. Additionally, it would be possible to
integrate both receiver and transmitter functionality onto one
wafer rather than having two separate process flows. The silicon
photonics process could also be slightly altered such that the
electrical tracing going externally to an electronic board goes
through the electronic wafer rather than through the SiP wafer to
the opto-mechanical wafer. In this process flow, the first step of
designing the electronic wafer 300 would also need to design
through Si vias to the backside to match with standard PCB or
similar electronic board capabilities. The steps of designing and
fabricating the opto-mechanical wafer 100 would not need any of the
metallization described for the opto-mechanical wafer. The step of
bonding the opto-mechanical wafer 100 to the optoelectronic wafer
200 would only need index matching epoxy and no electrical
connection. According to another possible embodiment, the
opto-mechanical wafer 100 may still have the electronic connection
through the opto-mechanical wafer with the Silicon IC chip either
disposed on a common substrate or the stacked up module bonded onto
the Silicon IC, where the IC is a larger chip than the module.
[0125] Another variation to the method to manufacture
optoelectronic modules could be a mix of wafer-level integration
with chip-based integration used in silicon-based electronics. In
this implementation, wafer-level integration of just the two top
wafers, i.e. the optoelectronic wafer (GaAs, SiP or other) 200 and
the opto-mechanical wafer 100, is performed. In this case, the two
wafers 100 and 200 would be bonded solely with index-matching epoxy
and have no electrical connectivity while still maintaining the
advantages of wafer-level fabrication for the optical and fiber
attach elements. According to another embodiment, it is possible to
consider having metalization here for downward or flip chip
connections as well, for example, either through metal
redistribution layers and/or vias. The arrangement is shown in
FIGS. 8B, 9B, 10B and 11B with the IC mounted on the PCB, or as
shown below in FIG. 14 where the surface S200b of the
optoelectronic wafer would have a metal redistribution layer in
order to connect the VCSELs, PDs and Driver/Receiver circuitry.
[0126] This two-layer stack would form the sub-assembly to then be
diced into individual optoelectronic modules, which can be
electrically connected at the bottom of the module, i.e. the bottom
of the optoelectronic wafer, using the same via design as the
previous three-layer stack. Since the two-layer stack no longer
directly integrates the electronic wafer functionality into the
wafer-level integration, it is necessary to subsequently integrate
the singularized optoelectronic module, i.e. the diced two-layer
stack, with an electronic chip or a diced electronic wafer. One
possible method to do this final integration with an electronic
chip could be to bond the optoelectronic module directly on top of
an electronic chip or an interposer substrate typically referred to
as 2.5D or 3D integration in silicon processing. Alternatively, the
module could be soldered, e.g. through Surface Mount Technology
(SMT), directly to an electronic board, such as a PCB, with nearby
electronic chips with laser drive and receiver amplification.
[0127] Embodiments of a method to manufacture the optoelectronic
modules comprising at least two substrates cut out of a wafer stack
comprising at least the first (opto-mechanical) wafer 100 and the
second (optoelectronic) wafer 200 are described with reference to
FIGS. 13A and 13B.
[0128] FIG. 13A shows a wafer stack comprising the first
(opto-mechanical) wafer 100 comprising alignment components 160,
such as v-grooves, and light turning elements 170 based on TIR
(Total Internal Reflection). The first wafer 100 does not comprise
any electrical vias through the material of the first wafer 100,
for example a glass material. The wafer stack further comprises a
spacer wafer 600 bonded below the opto-mechanical wafer 100 and the
second (optoelectronic) wafer 200 arranged on the bottom side of
the spacer wafer 600. The optoelectronic wafer 200 can be made of
glass. Electronic components, for example a transceiver, and
optoelectronic components, for example, a VCSEL and/or a PD can be
placed on a surface of the optoelectronic wafer 200.
[0129] FIG. 13B shows a wafer stack comprising an opto-mechanical
wafer 100, a spacer wafer 600 and an optoelectronic wafer 200. The
opto-mechanical wafer 100 is placed on the top side of the wafer
stack and the optoelectronic wafer 200 is placed on the bottom side
of the wafer stack. The spacer wafer 600 is arranged between the
opto-mechanical wafer 100 and the optoelectronic wafer 200. The
optoelectronic wafer 200 may be configured as an electronic board,
for example a PCB with individual electronic and opto-electronic
components arranged on top of the electronic board within an
opening of the spacer wafer as shown below in FIG. 19.
Alternatively, the optoelectronic wafer 200 may be configured as a
SiP wafer with backside electrical connections.
[0130] According to an embodiment of a method to manufacture
optoelectronic modules, a water stack as shown in FIG. 13A is
provided. The wafer stack comprises a first (opto-mechanical) wafer
100 comprising a plurality of first (opto-mechanical) module
portions 101, wherein each of the first (opto-mechanical) module
portions 101 comprises at least one fixture 160, which is molded at
the wafer scale onto the surface of the first wafer 100, to hold an
optical fiber 2. Alternatively, the fixture can also be individual
injection molded elements that are bonded precisely to each
module.
[0131] Embodiments of a method to manufacture optoelectronic
modules as well as the corresponding optoelectronic modules are
described below with reference to FIGS. 14 to 19 showing the
corresponding optoelectronic modules manufactured by the method.
According to an embodiment of the method to manufacture the
optoelectronic modules, a first (opto-mechanical) wafer 100
comprising a plurality of first module portions 101 is provided,
wherein the first wafer 100 has a first surface S100a and an
opposite second surface S100b. A second (optoelectronic) wafer 200
comprising a plurality of second module portions 201 is provided,
wherein the second wafer 200 has a first surface S200a and an
opposite second surface S200h. Each of the second module portions
201 comprises at least one optoelectronic component 210.
[0132] The first wafer 100 is disposed onto the second wafer 200 to
provide a wafer stack such that the second surface S100b of the
first wafer 100 is placed opposite to the first surface S200a of
the second wafer 200 and each of the first module portions 101 is
aligned to a respective one of the second module portions 201 so
that light coupled in a respective one of the first module portions
201 is transferred to a respective one of the second module
portions 201 and is directed to the respective at least one
optoelectronic component 210 of the second module portions 201. The
wafer stack is diced into individual dies respectively comprising
one of the first (opto-mechanical) and one of the second
(optoelectronic) module portions for respectively forming one of
the optoelectronic modules 1.
[0133] According to a possible embodiment of the method to
manufacture the optoelectronic modules, each of the first module
portions 101 comprises at least a fixture 160 to hold an optical
fiber 2. The at least one fixture 160 is made by a wafer scale
process molding directly onto the first wafer 100 and/or using one
of a single wafer with molded elements and several stacked wafers
with varying holes and/or cut outs.
[0134] According to another possible embodiment of the method to
manufacture the optoelectronic modules, at least one passive
optical component 110 for each of the first module portions is
provided on the first surface S100a of the first wafer 100. The
first wafer 100 is disposed onto the second wafer 200 such that
light coupled into the respective at least one passive optical
component 110 of the first module portions 101 is coupled into the
respective at least one optoelectronic component 210 of the second
module portions 201.
[0135] According to another possible embodiment of the method to
manufacture the optoelectronic modules, at least one of the first
and second module portions 101, 201 is provided with at least one
passive optical component 110a, 110b. The first wafer 100 is
disposed onto the second wafer 200 to provide a wafer stack such
that each of the first module portions 101 is aligned to a
respective one of the second module portions 201 so that light
coupled out of the optical fiber 2 held in the respective at least
one fixture 160 of the first module portions 101 is coupled into
the respective at least one passive optical component 110a, 110b of
one of the first and second module portions 101, 201 at the first
side of the respective at least one passive optical component and
is coupled out at the second side of the respective at least one
optical component and is directed to the respective at least one
optoelectronic component 210 of the second module portions 201.
[0136] According to another possible embodiment of the method to
manufacture the optoelectronic modules, a respective one of the at
least one passive optical component 110a for each of the first
module portions 101 is placed on the second surface S100b of the
first wafer 100. The respective at least one optoelectronic
component 210 of the second module portions 201 is placed on the
first surface S200a of the second wafer 200.
[0137] According to another possible embodiment of the method to
manufacture the optoelectronic modules, a respective one of the at
least one passive optical component 110b for each of the second
module portions is placed on the first surface S200a of the second
wafer 200. The respective at least one optoelectronic component 210
of the second module portions 201 is placed on the second surface
S200b of the second wafer 200.
[0138] According to another possible embodiment of the method to
manufacture the optoelectronic modules, a respective first one of
the at least one passive optical component 110a for each of the
first module portions 101 is placed on the second surface S100b of
the first wafer 100. A respective second one of the at least one
passive optical component 110b for each of the second module
portions 201 is placed on the first surface S200a of the second
wafer 200. The respective at least one optoelectronic component 210
of the second module portions 201 is placed on the second surface
S200b of the second wafer 200.
[0139] According to another possible embodiment of the method to
manufacture the optoelectronic modules, the first wafer 100 is
provided with a respective at least one light turning element 170
for each of the first module portions 101. The light turning
element 170 is configured to change a direction of the light beam
so that light is coupled between the respective one of the at least
one optical fiber 2 coupled to the first module portions 101 and
the respective at least one passive optical component 110a, 110b of
the at least one first and second module portions 101, 201.
[0140] According to another possible embodiment of the method to
manufacture the optoelectronic modules, at least one respective
electronic component 310 is provided for each of the second module
portions 201. The respective at least one electronic component 310
is placed on one of the first and second surface S200a, S200b of
the second wafer 200.
[0141] According to another possible embodiment of the method to
manufacture the optoelectronic modules, a covering element 500 is
provided over the first surface S100a of the first wafer 100.
[0142] According to another possible embodiment of the method to
manufacture the optoelectronic modules, a spacer wafer 600 is
provided between the first wafer 100 and the second wafer 200.
Alternatively, a spacer layer made by molding directly onto the
first surface S200a of the second wafer 200 and/or the second
surface S100b of the first wafer 100 may be provided.
[0143] According to another possible embodiment of the method to
manufacture the optoelectronic modules, respective tapered and/or
straight etched holes 190 are provided for each of the first module
portions 101 in the material of the first wafer 100 to fix the
front face of the respective at least one optical fiber 2 coupled
to the first module portions 101 of the first wafer 100.
Alternatively, respective straight holes and respective molded
tapers for each of the first module portions 101 may be provided in
the material of the first water 100 to fix the front face of the
respective at least one optical fiber 2 coupled to the first module
portions 101 of the first wafer 100.
[0144] According to a possible embodiment of the method to
manufacture the optoelectronic modules, either the first and second
wafers 100, 200 are respectively configured as glass wafers, or the
first wafer 100 is configured as a glass wafer and the second wafer
200 is configured as one of a printed circuit board, ceramic
substrate, electronic board and an SiP wafer.
[0145] The respective at least one passive optical component 110,
110a, 110b of one of the first and second module portions 101, 201
may comprise an optical lens. The respective at least one
optoelectronic component 210 of the second module portions 201 may
be configured as an optical emitter and/or an optical receiver. The
respective at least one electronic component 310 of the second
module portions 201 may be configured as an electrical driver
and/or an electrical amplifier.
[0146] Several embodiments of an optoelectronic module comprising
at least two stacked substrates, for example a first
(opto-mechanical) substrate comprising optical components such as
optical alignment components and beam deflection components and a
second (optoelectronic) substrate comprising electronic and
optoelectronic components such as transceiver ICs, VCSELs or PDs
being cut out of the wafer stack of the bonded optoelectronic wafer
200 and an opto-mechanical wafer 100 are shown in FIGS. 14 to 19.
The optoelectronic modules shown in FIGS. 14 to 19 additionally
comprise other components, for example a spacer polymer. The spacer
polymer could be a wafer in itself and thus many of the embodiments
shown in FIGS. 14 to 19 may be based on 2-4 stacked wafers, as for
example shown for the 3 stacked wafers of FIG. 13A and 13B.
[0147] FIG. 14 shows an exploded view of an optoelectronic module 1
manufactured with the method as described with reference to the
wafer stack shown in FIG. 13A. The optoelectronic module comprises
an opto-mechanical substrate 100', an optoelectronic substrate 200'
and a spacer layer 180 that are cut out of the bonded wafer stack
comprising the opto-mechanical wafer 100, the optoelectronic wafer
200 and the spacer wafer 600 as shown in FIGS. 13A. A covering
element 500 is provided to be disposed on the first surface S100a
of the opto-mechanical substrate 100'.
[0148] A fixture 160 to hold the optical fibers 2 is arranged on
the first surface S100a of the opto-mechanical substrate 100'. A
light turning element 170 including a fiber alignment structure is
placed on the first surface S100a of the opto-mechanical substrate
100'. The light turning element 170 is either molded directly onto
the surface or placed with precision and created using injection
molding. First passive optical components 110a, for example lenses,
are placed on the second surface S100b of the opto-mechanical
substrate 100'. Spacer layers 180 are provided, wherein the spacer
layers 180 may be placed on the second surface S100b of the
opto-mechanical substrate 100' or on the first surface S200a of the
optoelectronic wafer 200 or both surfaces S100b and S200a. It is
also possible to provide a separate spacer wafer in various
manufacturing stackups. The opto-mechanical substrate 100' may be
configured as a glass substrate. The light turning element 170 with
the fiber alignment structure may be configured as a molded polymer
layer, and the first passive optical components 110a may be
configured as another molded polymer layer and the spacer layers
180 may be molded as another polymer or a separate machined wafer
and disposed on the glass substrate 100' fabricated as one
component.
[0149] The optoelectronic substrate 200' may comprise second
passive optical component 110b being disposed on a first surface
S200a of the optoelectronic substrate 200'. The second passive
optical components 110b may be configured as one molded polymer
layer being disposed on a glass substrate 200'. The optoelectronic
substrate 200' further comprises electronic components 310, such as
transceivers. Solder ball contacts 230 to reflow the module on a
PCB substrate and a metallization for an optoelectronic component
210, for example a VCSEL or a PD, are disposed on the second
surface S200b of the optoelectronic substrate 200'.
[0150] FIG. 15A shows a two-dimensional exploded view of the
optoelectronic module 1 as shown in FIG. 14 in a perspective
exploded view. FIGS. 15B shows an embodiment of an optoelectronic
module 1 of FIG. 15A manufactured with the method described with
reference to the wafer stack shown in FIG. 13A. The optoelectronic
module comprises an opto-mechanical substrate 100', an
optoelectronic substrate 200' and a spacer layer 180 that are cut
out of the bonded wafer stack comprising the opto-mechanical wafer
100, the optoelectronic wafer 200 and the spacer wafer 600 as shown
in FIG. 13A. The opto-mechanical substrate 100' and the
optoelectronic substrate 200' may be made of glass being
transparent for the light transferred in the optical fiber 2. A
covering element 500 that can be made of glass or plastic is
disposed on the first surface S100a of the opto-mechanical
substrate 100'.
[0151] A fixture 160 to hold the optical fiber 2 is arranged on the
first surface S100a of the opto-mechanical substrate 100'. Light
turning elements 170a and 170b are disposed on the first surface
S100a of the opto-mechanical substrate 100'. First passive optical
components 110a, for example lenses, are placed on the second
surface S100b of the opto-mechanical substrate 100'. Spacer layers
180 are placed on the second surface S100b of the opto-mechanical
substrate 100' and on the first surface S200a of the optoelectronic
substrate 200'. The opto-mechanical substrate 100' may be
configured as a glass substrate.
[0152] The optoelectronic substrate 200' comprises second passive
optical components Hob, for example lenses, being disposed on the
first surface S200a of the optoelectronic substrate 200'. The
optoelectronic substrate 200' further comprises electronic
components 310, such as transceivers. Solder ball contacts 230 to
reflow the module on a PCB substrate and optoelectronic components
210, for example a VCSEL or a PD, are disposed on the second
surface S200b of the optoelectronic substrate 200'.
[0153] The optoelectronic module 1 has a first optical path
comprising the light turning element 170a and the optical lens
110a. Light coupled out of the optoelectronic component 210a being
configured as a VCSEL is coupled out of the VCSEL 210a and coupled
in the lens 110a. The light is coupled through the opto-mechanical
substrate 100' into the light turning element 170a from which it is
deflected towards the optical fiber 2. The optoelectronic module 1
has a second optical path comprising the light turning element 170b
and the optical lens 110b. Light coupled out of the optical fiber 2
is deflected by the light turning element 170b through the
opto-mechanical substrate 100' towards the optical lens 110b. The
lens 110b focuses the light to the optoelectronic component 210b
that can be configured as a photodiode.
[0154] FIGS. 16A and 16B respectively show other embodiments of an
optoelectronic module 1 manufactured with the method described with
reference to the wafer stack shown in FIG. 13A. The optoelectronic
modules shown in FIGS. 16A and 16B comprise an opto-mechanical
substrate 100' and an optoelectronic substrate 200' that are cut
out of the bonded wafer stack comprising the opto-mechanical wafer
100 and the optoelectronic wafer 200 as shown in FIG. 13A The
opto-mechanical substrate 100' may be made of a material being
opaque for the light transferred in the optical fiber 2. A covering
element 500 that can be made of glass or plastic is disposed on the
first surface S100a of the opto-mechanical substrate 100'.
[0155] The optoelectronic module 1 shown in FIG. 16A comprises the
same arrangement of the fixture 160 and the light-turning elements
170a, 170b on the first surface S100a of the opto-mechanical
substrate 100' and first passive optical components 110a, for
example lenses, as well as spacer layers 180 on the second surface
S100b of the opto-mechanical substrate 100' as shown in FIG.
15A.
[0156] The optoelectronic substrate 200' comprises the same
arrangement of the second passive optical components 110b, for
example lenses, and spacer layers 180 on the first surface S200a of
the optoelectronic substrate 200' and electronic components 310,
such as transceivers, solder ball contacts 210 and optoelectronic
components 210, for example a VCSEL or a PD, on the second surface
S200b of the optoelectronic substrate 200' as shown for the
optoelectronic module in FIG. 15A.
[0157] The opto-mechanical substrate 100' may comprise cavities 101
within the opaque material of the opto-mechanical substrate 100'.
The cavities may be filled with a material of polymer to provide a
light transmission path between the light turning elements 170a,
170b and the first and second passive optical components 110a and
110b.
[0158] FIG. 16B shows a similar embodiment of an optoelectronic
module as shown in FIG. 16A with the difference that first passive
optical components 110a and second passive optical components 110b,
such as lenses, are disposed opposite to each other on the second
surface S100b of the opto-mechanical substrate 100' and the first
surface S200a of the optoelectronic substrate 200'. Additional
embodiments not shown can have the optical components placed in
other configurations, such as both on surface S100b or both on
surface S200a.
[0159] FIGS. 17A and 17B respectively show an embodiment of an
optoelectronic module 1 manufactured with the method described with
reference to the water stack shown in FIG. 13A. The optoelectronic
module comprises an opto-mechanical substrate 100' and an
optoelectronic substrate 200' that are cut out of the bonded wafer
stack comprising the opto-mechanical wafer 100 and the
optoelectronic wafer 200 as shown in FIG. 13A. The opto-mechanical
substrate 100' and the optoelectronic substrate 200' may be made of
glass being transparent for the light transferred in the optical
fiber 2. The top substrate 100' acts as supporting means for the
opto-mechanical components and additionally as a cover. The light
turning elements 170a, 170b acts as mirrors having a metal or
similar coating to be reflective.
[0160] Light turning elements 170a and 170b as well as a fiber
alignment fixture 160 are arranged on the second surface S100b of
the opto-mechanical substrate 100'. Passive optical components
110a, 110b as well as a vertical adjustment polymer layer 250 are
disposed on the first surface S200a of the optoelectronic substrate
200'. The vertical adjustment polymer layer 250 can be a portion of
the spacer wafer 600. The optoelectronic substrate 200' further
comprises electronic components 310, such as transceivers, solder
ball contacts 230 to reflow the module on a PCB substrate and
optoelectronic components 210, for example a VCSEL or a PD, that
are disposed on the second surface S200b of the optoelectronic
substrate 200'.
[0161] The optoelectronic module 1 shown in FIG. 17B is embodied in
a similar way as shown for the optoelectronic module of FIG. 17A
with the difference that a curvature is added to the light turning
elements 170a and 170b being configured as metal coated
mirrors.
[0162] FIGS. 18A to 18C respectively show embodiments of an
optoelectronic module 1 manufactured with the method described with
reference to the water stack shown in FIG. 13A. The optoelectronic
module comprises an opto-mechanical substrate 100' and an
optoelectronic substrate 200' that are cut out of the bonded wafer
stack comprising the opto-mechanical wafer 100 and the
optoelectronic wafer 200 as shown for the wafer stack in FIG.
13A.
[0163] The opto-mechanical substrate 100' comprises cavities 101 to
insert optical fibers 2. Spacer layers 180 are disposed on the
first and second surface S100a and S100b of the opto-mechanical
substrate 100'. The optoelectronic substrate 100' can be made of
glass being transparent for the light transferred through the
optical fiber 2 and for arranging electrical traces. First and
second passive optical components 110a and 110b, for example
lenses, are disposed on the first surface S200a of the
optoelectronic substrate 200'. The optoelectronic substrate 200'
further comprises electronic components 310, such as transceivers,
solder ball contacts 230 to reflow the module on a PCB substrate
and optoelectronic components 210, for example a VCSEL, or a PD,
that are disposed on the second surface S200b of the optoelectronic
substrate 200'. The optoelectronic components and the electronic
components are arranged on the same substrate for electrical
integrity.
[0164] The opto-mechanical substrate 100' may be made of glass,
wherein the cavities 101 are configured as tapered etched holes
190. According to the embodiment of the optoelectronic module shown
in FIG. 18A, the optical fibers 2 are inserted in the tapered
etched holes. According to the embodiment of the optoelectronic
module shown in FIG. 18B, the opto-mechanical substrate 100' is
configured to be made of a material being opaque for the light
transferred through the optical fibers 10. The opto-mechanical
substrate 100' comprises cavities 101 formed as tapered polymer
molded holes 190 in which the optical fibers 2 are inserted. The
optoelectronic module 1 shown in FIG. 18C is embodied similar as
shown for the optoelectronic module of FIG. 18B with the difference
that the polymer molded holes do not taper and are provided with a
hard cladding or ferrule 5 acting a fiber stop means.
[0165] FIG. 19 shows an embodiment of an optoelectronic module 1
comprising the opto-mechanical substrate 100' and the
optoelectronic substrate 200'. In contrast to the embodiments shown
in FIGS. 14 to 18C the optoelectronic components, such as VCSEL/PD,
are wirebonded onto an optoelectronic wafer 200 being embodied as a
PCB or similar electronic board with electrical traces and vias to
connect this module externally to a larger PCB or electronic board
later after dicing. The stack arrangement is manufactured at the
wafer scale with the PCB being a wafer.
[0166] The substrate 100' may be made of glass having a first
surface S100a on which a fixture 160 for holding and aligning an
optical fiber 2 and light turning elements 170a, 170b are disposed.
A cap 500 made of glass or a plastic material is disposed on the
first surface S100a of the opto-mechanical substrate 100'. Passive
optical components 170, such as lenses, are disposed on a second
surface S100b of the opto-mechanical substrate 100'.
[0167] The opto-mechanical substrate 100' is mounted onto the
optoelectronic substrate 200', for example a PCB. The
optoelectronic substrate 200' comprises optoelectronic components
210a, 210b being embodied as VCSELs or PDs and arranged on a first
surface S200a of the optoelectronic substrate. An electronic
component 310, for example a transceiver IC, may also be mounted
onto the first surface S200a. of the optoelectronic substrate 200'.
Electrical contact pads are provided on the second surface S200b of
the optoelectronic substrate 200'. A spacer layer 180 is arranged
between the second surface S100b of the opto-mechanical substrate
100' and the first surface S200a of the optoelectronic substrate
200'. The scale unit given in FIG. 19 is just a possible
orientation and does not restrict the components of the embodiment
to the specified values.
[0168] The opto-mechanical substrate 100' is aligned to the
optoelectronic substrate 200' at the wafer scale so that light may
be transferred through a first optical path from the optoelectronic
transmitter 210a through the lens 110a and the glass substrate 100'
to the light turning mirror 170a that deflects the light such that
it is coupled into the optical fiber 2. The opto-mechanical
substrate 100' is further aligned to the optoelectronic substrate
200' so that light may be transferred through a second optical path
from the optical fiber 2 to the light turning mirror 170b that
deflects the light towards the lens 110b from which the light is
coupled out towards the optoelectronic receiver 210b.
[0169] In conclusion, the different embodiments of the method to
manufacture optoelectronic components substantially reduce the cost
of assembling devices comprising electronic integrated circuits,
optoelectronic sources and detectors, optical components and
waveguides such as lenses and fiber. The embodiments of the method
allow fabricating multiple devices in parallel and aligning them at
the wafer-scale thereby increasing assembly throughput. Testable
sub-assemblies are fabricated by dicing the stacked wafers that
allows verification of the critical precision alignments and device
functionality prior to additional assembly thereby reducing the
loss of other components due to fallout. The optoelectronic
sub-assemblies built by the described embodiments of the method are
compatible with low cost electronic circuit board fabrication
technology, such as surface-mount technology (SMT). The embodiments
of the method provide a path toward high-speed assembly at low-cost
due to tight alignment tolerances and controlled electrical
connectivity and allow volume manufacturing that can scale cost
down as demand increases. Furthermore, the need for wire-bonding in
some embodiments is eliminated which improves impedance control of
the electrical lines as well as vibration tolerance for automotive
or other such applications.
[0170] Another benefit to the specified approach is that the
placement of the optical emitter/receiver can be nearly anywhere in
the plane of the module instead of near the perimeter as in many
pick-and-place designs where the electronic chip and optoelectronic
chips are on a common substrate. With this freedom, the likely
ideal placement would be toward the center of the module so that
the mechanical features holding the fiber in alignment can also be
centered.
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