U.S. patent application number 11/790029 was filed with the patent office on 2007-08-30 for electrical connection for optoelectronic devices.
This patent application is currently assigned to DIGITAL OPTICS CORPORATION. Invention is credited to John Barnett Hammond, Hongtao Han, Alan D. Kathman, Jay Mathews.
Application Number | 20070200132 11/790029 |
Document ID | / |
Family ID | 26956107 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070200132 |
Kind Code |
A1 |
Kathman; Alan D. ; et
al. |
August 30, 2007 |
Electrical connection for optoelectronic devices
Abstract
A structure having an optical element thereon has a portion of
the structure extending beyond a region having the optical element
in at least one direction. The structure may include an active
optical element, with the different dimensions of the substrates
forming the structure allowing access for the electrical
interconnections for the active optical elements. Different dicing
techniques may be used to realize the uneven structures.
Inventors: |
Kathman; Alan D.;
(Charlotte, NC) ; Han; Hongtao; (Mooresville,
NC) ; Mathews; Jay; (Huntersville, NC) ;
Hammond; John Barnett; (Charlotte, NC) |
Correspondence
Address: |
DIGITAL OPTICS CORPORATION
C/O LEE & MORSE, P.C.
3141 FAIRVIEW PARK DRIVE, SUITE 500
FALLS CHURCH
VA
22042
US
|
Assignee: |
DIGITAL OPTICS CORPORATION
Charlotte
NC
28262
|
Family ID: |
26956107 |
Appl. No.: |
11/790029 |
Filed: |
April 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10945090 |
Sep 21, 2004 |
7208771 |
|
|
11790029 |
Apr 23, 2007 |
|
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|
09983278 |
Oct 23, 2001 |
6798931 |
|
|
10945090 |
Sep 21, 2004 |
|
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60273321 |
Mar 6, 2001 |
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Current U.S.
Class: |
257/99 |
Current CPC
Class: |
H01S 5/023 20210101;
H01L 2924/0002 20130101; H01S 5/02325 20210101; H01S 5/0235
20210101; H01S 5/0201 20130101; Y10T 156/1052 20150115; H01S 5/0233
20210101; H01S 5/02345 20210101; G02B 6/4201 20130101; G02B 6/4204
20130101; H01S 5/183 20130101; G02B 6/4274 20130101; H01L 2924/0002
20130101; H01L 2924/00 20130101 |
Class at
Publication: |
257/099 |
International
Class: |
H01L 33/00 20060101
H01L033/00 |
Claims
1-14. (canceled)
15. A device, comprising: an active element on a first substrate; a
second substrate; a bonding pad on one of the first and second
substrates; an attachment mechanism adapted to secure the first
substrate and the second substrate in a vertical direction, a
portion of the first and second substrates having the bonding pad
thereon extending further in at least one direction than the other
substrate; and an electrical interconnection extending from the
active element to the bonding pad.
16. The device of claim 15, further comprising a spacer between the
first and second substrates.
17. The device of claim 16, wherein the spacer is formed in a
spacer substrate.
18. The device of claim 17, wherein the first and second substrates
are attached via the spacer substrate.
19. (canceled)
20. The device of claim 15, wherein the electrical bonding pad is
on the first substrate.
21. The device of claim 15, wherein the bonding pad is on the
second substrate.
22. The device of claim 21, further comprising an electrically
conductive material between the first and second substrates.
23. The device of claim 22, wherein the electrically conductive
material includes solder balls.
24. The device of claim 22, wherein the electrically conductive
material is on an element between the first and second
substrates.
25. The device of claim 30, wherein the feature is an optical
element.
26. The device of claim 30, wherein the feature is a hole.
27. The device of claim 30, wherein the feature is an
indentation.
28.-29. (canceled)
30. The device of claim 15, further comprising a feature on the
second substrate.
31. The device of claim 30, wherein the feature is on a surface of
the second substrate facing the first substrate.
32. The device of claim 30, wherein the feature is on an upper
surface of the second substrate facing the first substrate.
33. The device of claim 16, wherein sidewalls of the spacer facing
the active element are beveled.
34. The device of claim 15, wherein the attachment mechanism and
the second substrate seal the active element.
35. The device of claim 34, wherein the seal is hermetic.
36. The device of claim 15, wherein the attachment mechanism
includes electrically conductive material.
37. The device of claim 36, wherein the electrically conductive
material includes solder balls.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application based on pending
application Ser. No. 10/945,090, filed Sep. 21, 2004, which in turn
is a division of application Ser. No. 09/983,278, filed Oct. 23,
2001, which claims priority under 35 U.S.C. .sctn.119 to U. S.
Provisional Application 60/273,321 entitled "Separating of
Electro-Optical Integrated Modules and Structures Formed Thereby"
filed Mar. 3, 2001, the entire contents of which are hereby
incorporated by reference in their entirety for all purposes.
FIELD OF THE INVENTION
[0002] The present invention is directed to techniques for
separating modules on a wafer, particularly for use in creating
wafer level assembly of electro-optical modules with manageable
electrical input-output, and the structures formed thereby. The
present invention is further directed to providing a mechanical
support ledge for integrating an optical module with another
structure, e.g., a circuit board.
BACKGROUND OF THE INVENTION
[0003] One obstacle encountered in integrating electrical devices
with optical components on a wafer level is how to manage the
electrical connections. Typical wafer assembly and separating can
yield an excellent optical assembly, but with no feasible location
for electrical connections, as shown n FIG. 1. In FIG. 1, the
module includes an active element 10 mounted on a submount 20 and
an optics block 30 with an optical element 40 thereon.
Interconnection lines 22 are formed on the submount 20 to provide
electrical signals to and/or from the active element 10. The active
element 10, e.g., a vertical cavity surface emitting laser (VCSEL),
can bonded to the submount 20 at the wafer level, optics and any
spacers aligned thereto and integrated therewith. When the
individual modules are separated, the electrical connections 22 to
the active element 10 are difficult to access.
[0004] Another problem arises when attempting to integrate optical
element elements formed on a wafer level with planar systems, such
as a printed circuit board, or any system which is not to continue
the stacked structure of the wafer level constructions. Support and
alignment are both issues in this integration.
[0005] One potential solution is to assemble the optics and spacers
at the wafer level, then separate and bond to the individual
submounts. However, this does not take full advantage of wafer
level assembly.
SUMMARY OF THE INVENTION
[0006] The present invention is therefore directed to methods and
structures of providing interconnections to electro-optical
elements in an electro-optical module formed on a wafer level which
overcome at least one of the above disadvantages.
[0007] The present invention is also directed to methods and
structures of providing alignment and support for wafer based
integrated optical subassemblies with non-stacked systems that
overcome at least one of the above disadvantages.
[0008] At least one of the above and other objects may be realized
by providing a method of creating an electro-optic module including
providing an active element wafer having a plurality of active
elements thereon; aligning a feature wafer having features thereon
to the active element wafer, providing an electrical bonding pad on
at least one of the active element wafer and the feature wafer,
attaching the feature wafer and the active element wafer to form an
integrated wafer, and separating dies from the integrated wafer, at
least one die including at least one active element and a feature,
said separating including separating along different vertical paths
through the integrated wafer such that at least a portion of the
wafer having the electrical bonding pad extends beyond the other
wafer.
[0009] At least one of the above and other objects may be realized
by providing an integrated electro-optical module including an
active element on a first substrate, a feature on a second
substrate, a bonding pad on one of the first and second substrates,
the first substrate and the second substrate being attached in a
vertical direction to one another, a portion of the first and
second substrates having the bonding pad thereon extending further
in at least one direction than the other substrate.
[0010] At least one of the above and other objects may be realized
by providing an apparatus including a planar structure having a
hole therein, an optical element formed on a surface of a
substrate, the surface having the optical element thereon extending
through the hole of the planar structure, a mounting surface,
integrated with the substrate having the optical element, the
mounting surface extending in at least one direction beyond the
substrate; and an attachment mechanism securing the optical element
to the planar structure via the mounting surface.
[0011] These and other objects of the present invention will become
more readily apparent from the detailed description given
hereinafter. However, it should be understood that the detailed
description and specific examples, while indicating the preferred
embodiments of the invention, are given by way of illustration
only, since various changes and modifications within the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing and other objects, aspects and advantages will
be described with reference to the drawings, in which:
[0013] FIG. 1 is a schematic perspective view of an electro-optic
module which has been formed at the wafer level and separated in a
conventional manner;
[0014] FIG. 2A is a schematic side view of a plurality of
electro-optic modules before being separated in accordance with the
present invention;
[0015] FIG. 2B is a schematic side view of a plurality of
electro-optic modules of FIG. 2A after being separated in
accordance with the present invention;
[0016] FIG. 3A is a schematic side view of a plurality of
electro-optic modules before being separated in accordance with the
present invention;
[0017] FIG. 3B is a schematic side view of a plurality of
electro-optic modules of FIG. 3A after being separated in
accordance with the present invention;
[0018] FIG. 4A is a schematic side view of a plurality of
electro-optic modules before being separated in accordance with the
present invention;
[0019] FIG. 4B is a schematic side view of a plurality of
electro-optic modules of FIG. 4A after being separated in
accordance with the present invention;
[0020] FIG. 5 is a schematic side view of a plurality of
electro-optic modules before being separated in accordance with the
present invention;
[0021] FIG. 6A is a schematic side view of a plurality of
electro-optic modules before being separated in accordance with the
present invention;
[0022] FIG. 6B is a schematic side view of a plurality of
electro-optic modules of FIG. 6A after being separated in
accordance with the present invention;
[0023] FIG. 7A is a schematic side view of a plurality of
electro-optic modules before being separated in accordance with the
present invention;
[0024] FIG. 7B is a schematic side view of a plurality of
electro-optic modules of FIG. 7A after being separated in
accordance with the present invention;
[0025] FIG. 8 is a top view of the connection of an electro-optic
module shown in FIG. 2B with a flexible printed circuit board in
accordance with the present invention; and
[0026] FIG. 9 is a schematic top view of the mounting of an optical
subassembly with a circuit board in accordance with the present
invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] In the following description, for purposes of explanation
and not limitation, specific details are set forth in order to
provide a thorough understanding of the present invention. However,
it will be apparent to one skilled in the art that the present
invention may be practiced in other embodiments that depart from
these specific details. In other instances, detailed descriptions
of well-known devices and methods are omitted so as not to obscure
the description of the present invention with unnecessary details.
As used herein, the term "wafer" is to mean any substrate on which
a plurality of components are formed which are to be separated
prior to final use.
[0028] FIG. 2A is an exploded side view of the wafer level assembly
of a plurality of integrated electro-optical modules. As in FIG. 1,
the submount wafer 20 has an electro-optical element 10 thereon
with interconnection tracks 22. An optics wafer 30 having
corresponding optical elements 40 formed thereon is also provided.
A spacer wafer 50 separates the optics wafer 30 and the submount
wafer 20. The spacer wafer includes passages 52 therein which allow
light to pass between the optical element 40 and the active element
10. As shown in FIG. 2A, these passages 52 may be formed by etching
when the spacer wafer 50 is silicon.
[0029] In FIG. 2A, the spacer wafer 50 also includes indentations
54, here also formed by etching. These indentations 54 are provided
over the bond site 24 so that upon separating along lines 62, 64,
the bond site 24 will be accessible in the separated module, as
seen in FIG. 2B. This facilitates electrical connections required
to the electro-optical element 10. The separating may include
dicing the optics wafer 30 and the spacer wafer 50 along line 62
and dicing through all three wafers along line 64. Alternatively, a
wide blade may be used to dice the entire width between lines 62,
64 through the optics wafer 30 and the spacer wafer 50, and then
using a thin blade to dice only the submount wafer 20. The attached
structure may be flipped to facilitate dicing of only the submount
wafer 20.
[0030] An alternative configuration is shown in FIG. 3A and 3B, in
which the spacer wafer includes holes 56 therein over the bond site
24, rather than the indentations 54. The separating lines 65, 64
remain the same and may be realized in either process noted above.
However, the resulting structure will not have even edges of the
optics wafer 30 and the spacer wafer 50.
[0031] Another configuration is shown in FIGS. 4A and 4B. Here,
rather than forming the same active element 10--bonding site 24
pairs on the submount wafer 20, adjacent structures will be mirror
images of one another. This allows large indentations 58 to be
placed over two bonding site 24, 24'. The separating along
separating line 76 may be performed in a conventional manner.
Separating along separating lines 70, 72 is only through the optics
wafer 30 and the spacer wafer 50, and may be realized either by
dicing along either line or with a thick dicing blade covering the
width of the gap between separating lines 70, 72. The submount
wafer 20 is then separated along separating line 74, preferably
using a thin blade.
[0032] FIG. 5 illustrates another configuration, requiring less
separating. Here, the spacer wafer again includes the holes 56. The
optics wafer 30 also includes holes 36, here etched in the optics
wafer 30, isolating the different optics needed for each module.
Also as shown herein, the submount 20 includes two electro-optical
elements 10, 12 requiring interconnection. Here the electro-optical
elements are different from one another, with the electro-optical
element 12 being monolithically integrated with the submount wafer
20. Additional optical elements 42 are provided on the optical
wafer 30 for the electro-optical element 12. Here, only separation
of the submount wafer 20 along separating line 80 is required to
realize the individual modules.
[0033] Another alternative is shown in FIGS. 6A-6B. Here, a bonding
pad 124 is provided on the optics wafer 30. An interconnection line
122 connecting the active element 10 and the bonding pad 124 would
be on both the mount wafer 20 and the optics wafer 30. As shown on
FIGS. 6A and 6B, the bonding between the mount wafer 20 and the
optics wafer 30 is via an electrically conductive material, here
shown as solder balls 90. Alternatively, the spacer used in the
previous configurations could be coated with metal where needed to
provide the lead from the active element 10 to the bonding pad 24
on the optics wafer 30. Now the separating lines 92, 94, 96 lead to
a separation of the module that results in the optics wafer 30
extending beyond the mount wafer 20 in at least one direction,
i.e., so that the bonding pad 124 is easily accessible.
[0034] Another alternative is shown in FIGS. 7A-7B. Here, one
bonding pad 124 is provided on the optics wafer 30 while another
bonding pad 24 is provided on the mount wafer 20. A spacer wafer 50
is also provided in this configuration. The interconnection line
122 connecting the bonding pad 124 and the active element 10 would
be on the mount wafer 20, the spacer wafer 50 and the optics wafer
30. As shown on FIGS. 7A and 7B, the interconnection line 122
follows the spacer wafer 50 between the mount wafer 20 and the
optics wafer 30. Alternatively, a metal or other electrically
conductive material may be patterned on the wafer, and the
interconnection line 122 being only on the mount wafer 20 and the
spacer wafer 30, with the electrically conductive material on the
spacer wafer 50 providing connection therebetween. Now separating
lines 93, 95, 97, 99 lead to a separation of the module that
results in the optics wafer 30 extending beyond the mount wafer 20
in at least one direction, i.e., so that the bonding pad 124 is
easily accessible, and the mount wafer 20 extending beyond the
optics wafer 30 in at least one direction, i.e., so that the
bonding pad 24 is easily accessible.
[0035] As shown in FIG. 8, a flexible printed circuit board (PCB)
100 may be directly attached to the modules formed by any of the
above configurations. While the above configurations show a
cross-section of the modules, it is to be understood that any of
the electro-optical element--bonding site pairs may be an array
thereof, as shown in module 110 of FIG. 8. Due to the separating
discussed above, a step 26 formed by the extension of the wafer
having the bonding sites 24 thereon readily provides electrical
connection to another device, here a PCB 100. Further, the module
110 may be separated to provide steps 28 in the wafer having the
bonding pads 24 thereon, here shown as the mount wafer 20, on
either side of the other wafer, here shown as the optics wafer 30,
to facilitate mechanical strain relief for the flex lead of the
PCB. The steps 28 may extend around the whole perimeter.
[0036] Even if electrical interconnections are not to be provided
on the steps 28, when integrating an optical subassembly formed on
a wafer level with a system which is not t be stacked as the rest
of the wafer assembly, these steps 28 may be used to provide
support and/or alignment features. For example, as shown in FIG. 9,
an optical subassembly 130 to be mounted in a circuit board 120
having a hole 125 therein for receiving the optical subassembly 130
may include steps 128 to provide mechanical support and/or
alignment to the circuit board. The steps 128 may extend around the
entire perimeter of the optical subassembly 130. The optical
subassembly 130 and the steps 128 may be formed on a wafer level.
The steps 128 may include alignment features for facilitating
alignment of the circuit board 120 and the optical subassembly 130.
The steps 128 may provide mechanical mounting surface for mounting
the optical subassembly 130 to the circuit board 120. The use of
the steps 128 for attachment also allows the bonding material to be
kept out of the optical plane.
[0037] It will be obvious that the invention may be varied in a
plurality of ways, such as the use of different bonding materials,
extension in one or more directions, and different, or no, spacer
configurations. Such variations are not to be regarded as a
departure from the scope of the invention. All such modifications
as would be obvious to one skilled in the art are intended to be
included within the scope of the appended claims.
* * * * *