U.S. patent application number 11/782376 was filed with the patent office on 2008-08-07 for conductor fabrication for optical element.
Invention is credited to Hing Wah Chan.
Application Number | 20080185039 11/782376 |
Document ID | / |
Family ID | 39675132 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080185039 |
Kind Code |
A1 |
Chan; Hing Wah |
August 7, 2008 |
CONDUCTOR FABRICATION FOR OPTICAL ELEMENT
Abstract
A system may provide an optical element including conductive
material deposited on the optical element using a thick film
process, dielectric material disposed on the conductive material
and defining an aperture created using photolithography, the
aperture exposing a portion of the conductive material, and a solar
cell comprising an electrical contact coupled to the exposed
portion of the conductive material. Some aspects provide deposition
of conductive material on an optical element using a thick film
process, deposition of dielectric material on the conductive
material, creation of an aperture in the dielectric material using
photolithography to expose a portion of the conductive material,
and coupling of an electrical contact of a solar cell to the
exposed portion of the conductive material.
Inventors: |
Chan; Hing Wah; (San Jose,
CA) |
Correspondence
Address: |
BUCKLEY, MASCHOFF & TALWALKAR LLC
50 LOCUST AVENUE
NEW CANAAN
CT
06840
US
|
Family ID: |
39675132 |
Appl. No.: |
11/782376 |
Filed: |
July 24, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60899150 |
Feb 2, 2007 |
|
|
|
Current U.S.
Class: |
136/256 ;
430/314; 430/319 |
Current CPC
Class: |
H01L 31/0547 20141201;
H01L 2224/05568 20130101; H01L 2924/00014 20130101; H01L 31/054
20141201; H01L 24/16 20130101; H01L 2224/05573 20130101; H01L
2224/13101 20130101; H01L 2224/0554 20130101; H01L 24/13 20130101;
Y10T 156/10 20150115; H01L 2224/13101 20130101; H01L 2224/16237
20130101; H01L 2924/00014 20130101; H01L 2924/014 20130101; H01L
2224/05599 20130101; H01L 2924/00014 20130101; H01L 2224/0555
20130101; H01L 2224/0556 20130101; H01L 2924/00014 20130101; Y02E
10/52 20130101; H01L 2924/00014 20130101 |
Class at
Publication: |
136/256 ;
430/314; 430/319 |
International
Class: |
H01L 31/00 20060101
H01L031/00; G03C 5/00 20060101 G03C005/00 |
Claims
1. A method comprising: depositing conductive material on an
optical element using a thick film process; depositing dielectric
material on the conductive material; creating an aperture in the
dielectric material using photolithography to expose a portion of
the conductive material; and coupling an electrical contact of a
solar cell to the exposed portion of the conductive material.
2. A method according to claim 1, wherein the dielectric material
comprises thick photoresist, and wherein creating the aperture
comprises: masking the thick photoresist in accordance with a
location of the aperture; exposing the masked photoresist; and
removing portions of the thick photoresist corresponding to the
location of the aperture.
3. A method according to claim 1, wherein creating the aperture
comprises: depositing thin photoresist on the dielectric material;
masking the thin photoresist in accordance with a location of the
aperture; exposing the masked photoresist; removing portions of the
thin photoresist corresponding to the location of the aperture; and
etching away portions of the dielectric material corresponding to
the location of the aperture.
4. A method according to claim 1, wherein creating the aperture
comprises: depositing thin photoresist on the conductive material;
masking the thin photoresist in accordance with a location of the
aperture; exposing the masked photoresist; and removing portions of
the thin photoresist corresponding to the location of the aperture,
wherein depositing the dielectric material comprises depositing the
dielectric material on the thin photoresist.
5. A method according to claim 1, wherein the conductive material
deposited on the optical element defines a window from which light
may pass out of the optical element, and wherein the electrical
contact of the solar cell is coupled to the exposed portion of the
conductive material such that an optically-active area of the solar
cell is aligned with the window.
6. A method according to claim 1, wherein depositing the conductive
material on the optical element comprises: placing a stencil on the
optical element; and spraying molten conductive material on the
stencil and the optical element.
7. A method according to claim 1, wherein depositing the conductive
material on the optical element comprises: placing a stencil on the
optical element; and depositing a paste of conductive material onto
the stencil and the optical element.
8. A method according to claim 1, further comprising: depositing a
reflective material on the optical element; and depositing an
electrical isolator on the reflective material, wherein the
conductive material is deposited on the electrical isolator.
9. A method according to claim 8, wherein the conductive material
deposited on the optical element defines a window from which light
may pass out of the optical element, and wherein the electrical
contact of the solar cell is coupled to the exposed portion of the
conductive material such that an optically-active area of the solar
cell is aligned with the window.
10. An apparatus comprising: an optical element comprising
conductive material deposited on the optical element using a thick
film process; dielectric material disposed on the conductive
material and defining an aperture created using photolithography,
the aperture exposing a portion of the conductive material; and a
solar cell comprising an electrical contact coupled to the exposed
portion of the conductive material.
11. An apparatus according to claim 10, wherein the dielectric
material comprises thick photoresist, and wherein creating the
aperture was created by masking the thick photoresist in accordance
with a location of the aperture, exposing the masked photoresist,
and removing portions of the thick photoresist corresponding to the
location of the aperture.
12. An apparatus according to claim 10, wherein the aperture was
created by depositing thin photoresist on the dielectric material,
masking the thin photoresist in accordance with a location of the
aperture, exposing the masked photoresist, removing portions of the
thin photoresist corresponding to the location of the aperture, and
etching away portions of the dielectric material corresponding to
the location of the aperture.
13. An apparatus according to claim 10, wherein the aperture was
created by depositing thin photoresist on the conductive material,
masking the thin photoresist in accordance with a location of the
aperture, exposing the masked photoresist, and removing portions of
the thin photoresist corresponding to the location of the aperture,
and wherein depositing the dielectric material comprises depositing
the dielectric material on the thin photoresist.
14. An apparatus according to claim 10, wherein the conductive
material deposited on the optical element defines a window from
which light may pass out of the optical element, and wherein the
electrical contact of the solar cell is coupled to the exposed
portion of the conductive material such that an optically-active
area of the solar cell is aligned with the window.
15. An apparatus according to claim 10, wherein the conductive
material was deposited on the optical element by placing a stencil
on the optical element, and spraying molten conductive material on
the stencil and the optical element.
16. An apparatus according to claim 10, wherein the conductive
material was deposited on the optical element by placing a stencil
on the optical element, and rolling a paste of conductive material
onto the stencil and the optical element.
17. An apparatus according to claim 10, further comprising: a
reflective material deposited on the optical element; and an
electrical isolator deposited on the reflective material, wherein
the conductive material is deposited on the electrical
isolator.
18. An apparatus according to claim 17, wherein the conductive
material deposited on the optical element defines a window from
which light may pass out of the optical element, and wherein the
electrical contact of the solar cell is coupled to the exposed
portion of the conductive material such that an optically-active
area of the solar cell is aligned with the window.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application Ser. No. 60/899,150, filed on Feb. 2, 2007 and
entitled "Concentrated Photovoltaic Energy Designs", the contents
of which are incorporated herein by reference for all purposes.
BACKGROUND
[0002] 1. Field
[0003] Some embodiments generally relate to electrical systems
incorporating one or more optical elements. More specifically,
embodiments may relate to an optical element efficiently adapted
for interconnection to electrical devices.
[0004] 2. Brief Description
[0005] In some conventional devices, an optical element (e.g., a
lens) may include metal traces for interconnection to an electrical
circuit. The metal traces may be fabricated on and/or within the
optical element by any of several known techniques. Using thin film
lithographic techniques, metal is evaporated or sputtered onto an
optical element within a vacuum, photoresist is deposited on the
metal and patterned via masking and UV exposure, and areas of the
metal are etched in accordance with the photoresist pattern. Thin
film lithography may provide geometrically accurate traces but
entails significant expense.
[0006] Thick film techniques may alternatively be used for
fabricating metal traces onto an optical element. In accordance
with one thick film technique, a stencil is placed on an optical
element and a metal paste is applied to the stencil and the optical
element. The stencil is removed and the paste is heated to form a
solid metal material. Fabrication using thick film techniques is
typically less expensive than corresponding thin film-based
fabrication, but cannot provide tolerances required by certain
applications.
[0007] What is needed is a system to efficiently fabricate metal
traces on an optical element. Such a system may provide the
accuracy of thin film lithography where needed and cost advantages
of thick film fabrication where such accuracy is not required.
SUMMARY
[0008] To address at least the foregoing, some aspects provide a
method, means and/or process steps to deposit conductive material
on an optical element using a thick film process, deposit
dielectric material on the conductive material, create an aperture
in the dielectric material using photolithography to expose a
portion of the conductive material, and couple an electrical
contact of a solar cell to the exposed portion of the conductive
material.
[0009] In some aspects, the conductive material deposited on the
optical element defines a window from which light may pass out of
the optical element, and the electrical contact of the solar cell
is coupled to the exposed portion of the conductive material such
that an optically-active area of the solar cell is aligned with the
window. Deposition of the conductive material on the optical
element in some aspects includes placing a stencil on the optical
element and spraying molten conductive material on the stencil and
the optical element.
[0010] According to certain aspects, the dielectric material
comprises thick photoresist and creation of the aperture includes
masking the thick photoresist in accordance with a location of the
aperture, exposing the masked photoresist, and removing portions of
the thick photoresist corresponding to the location of the
aperture. In other aspects, creation of the aperture includes
deposition of thin photoresist on the dielectric material, masking
of the thin photoresist in accordance with a location of the
aperture, exposure of the masked photoresist, removal of portions
of the thin photoresist corresponding to the location of the
aperture, and etching away of portions of the dielectric material
corresponding to the location of the aperture.
[0011] Still other aspects include creation of the aperture by
depositing thin photoresist on the conductive material, masking the
thin photoresist in accordance with a location of the aperture,
exposing the masked photoresist, and removing portions of the thin
photoresist corresponding to the location of the aperture.
Deposition of the dielectric material may therefore comprise
depositing the dielectric material on the thin photoresist.
[0012] Some aspects provide an optical element including conductive
material deposited on the optical element using a thick film
process, dielectric material disposed on the conductive material
and defining an aperture created using photolithography, the
aperture exposing a portion of the conductive material, and a solar
cell comprising an electrical contact coupled to the exposed
portion of the conductive material. The dielectric material may
include thick photoresist, and the aperture may have been created
by masking the thick photoresist in accordance with a location of
the aperture, exposing the masked photoresist, and removing
portions of the thick photoresist corresponding to the location of
the aperture.
[0013] Alternatively, the aperture may have been created by
depositing thin photoresist on the dielectric material, masking the
thin photoresist in accordance with a location of the aperture,
exposing the masked photoresist, removing portions of the thin
photoresist corresponding to the location of the aperture, and
etching away portions of the dielectric material corresponding to
the location of the aperture.
[0014] In yet other aspects, the aperture may have been created by
depositing thin photoresist on the conductive material, masking the
thin photoresist in accordance with a location of the aperture,
exposing the masked photoresist, and removing portions of the thin
photoresist corresponding to the location of the aperture.
Deposition of the dielectric material may therefore include
depositing the dielectric material on the thin photoresist.
[0015] According to some aspects, the conductive material deposited
on the optical element defines a window from which light may pass
out of the optical element, and the electrical contact of the solar
cell is coupled to the exposed portion of the conductive material
such that an optically-active area of the solar cell is aligned
with the window.
[0016] Some aspects may also provide a reflective material
deposited on the optical element and an electrical isolator
deposited on the reflective material, wherein the conductive
material is deposited on the electrical isolator.
[0017] The claims are not limited to the disclosed embodiments,
however, as those in the art can readily adapt the description
herein to create other embodiments and applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The construction and usage of embodiments will become
readily apparent from consideration of the following specification
as illustrated in the accompanying drawings, in which like
reference numerals designate like parts.
[0019] FIG. 1 is a flow diagram of a method according to some
embodiments.
[0020] FIG. 2A is a perspective view of a portion of an optical
element with conductive material disposed thereon according to some
embodiments.
[0021] FIG. 2B is a cross-sectional view of a portion of an optical
element with conductive material disposed thereon according to some
embodiments.
[0022] FIG. 3A is a perspective view of a portion of an optical
element with conductive material and dielectric material disposed
thereon according to some embodiments.
[0023] FIG. 3B is a cross-sectional view of a portion of an optical
element with conductive material and dielectric material disposed
thereon according to some embodiments.
[0024] FIG. 4A is a perspective view of a portion of an optical
element with conductive material and dielectric material defining
apertures disposed thereon according to some embodiments.
[0025] FIG. 4B is a cross-sectional view of a portion of an optical
element with conductive material and dielectric material defining
apertures disposed thereon according to some embodiments.
[0026] FIG. 5 is a perspective view of a portion of an optical
element with conductive material and dielectric material disposed
thereon, and a solar cell with electrical contacts coupled to
portions of the conductive material exposed by apertures defined by
the dielectric material according to some embodiments.
[0027] FIG. 6 is a flow diagram of a method according to some
embodiments.
[0028] FIG. 7A is a perspective view of a transparent optical
element according to some embodiments.
[0029] FIG. 7B is a cross-sectional view of a transparent optical
element according to some embodiments.
[0030] FIG. 8A is a perspective view of a transparent optical
element with reflective material disposed thereon according to some
embodiments.
[0031] FIG. 8B is a cross-sectional view of a transparent optical
element with reflective material disposed thereon according to some
embodiments.
[0032] FIG. 9A is a perspective view of an optical element with an
electrical isolator disposed thereon according to some
embodiments.
[0033] FIG. 9B is a cross-sectional view of an optical element with
an electrical isolator disposed thereon according to some
embodiments.
[0034] FIG. 10A is a perspective view of an optical element with
conductive material disposed thereon according to some
embodiments.
[0035] FIG. 10B is a cross-sectional view of an optical element
with conductive material disposed thereon according to some
embodiments.
[0036] FIG. 11A is a close-up perspective view of dielectric
material applied to a pedestal of an optical element according to
some embodiments.
[0037] FIG. 11B is a cross-sectional view of dielectric material
applied to a pedestal of an optical element according to some
embodiments.
[0038] FIG. 12A is a close-up perspective view of photoresist
applied to dielectric material according to some embodiments.
[0039] FIG. 12B is a cross-sectional view of photoresist applied to
dielectric material according to some embodiments.
[0040] FIG. 13A is a close-up perspective view of exposed and
developed photoresist disposed on dielectric material according to
some embodiments.
[0041] FIG. 13B is a cross-sectional view of exposed and developed
photoresist disposed on dielectric material according to some
embodiments.
[0042] FIG. 14A is a close-up perspective view of dielectric
material defining apertures exposing conductive material on an
optical element according to some embodiments.
[0043] FIG. 14B is a cross-sectional view of dielectric material
defining apertures exposing conductive material on an optical
element according to some embodiments.
[0044] FIG. 15 is a close-up perspective view of an optical element
including a solar cell according to some embodiments.
DETAILED DESCRIPTION
[0045] The following description is provided to enable any person
in the art to make and use the described embodiments and sets forth
the best mode contemplated for carrying out some embodiments.
Various modifications, however, will remain readily apparent to
those in the art.
[0046] FIG. 1 is a flow diagram of process 100 according to some
embodiments. Process 100 may be performed by any combination of
machine, hardware, software and manual means.
[0047] Initially, at S110, conductive material is deposited on an
optical element using a thick film process. The conductive material
may comprise any combination of one or more currently- or
hereafter-known conductors, including but not limited to copper,
gold and nickel. According to some embodiments, the optical element
may be configured to manipulate and/or pass desired wavelengths of
light. The optical element may comprise any number of disparate
materials and/or elements (e.g., lenses, reflective surfaces and
optically-transparent portions).
[0048] The conductive material may be deposited at S110 by thermal
spraying, paste deposition, or other thick film techniques. Thick
film techniques may produce a layer of material that is less
geometrically precise than a layer deposited using thin film
techniques. However, thick film techniques may allow for
inexpensive deposition of the conductive material while also
satisfying relatively loose geometric tolerances that may be
required of the conductive layer.
[0049] Thermal spraying the conductive material may include heating
a powder of conductive material (e.g., copper) to a molten state
and spraying the molten powder onto the optical element. The molten
powder then cools on the optical element to produce a solid layer
of conductive material. Paste-based thick film techniques may
involve mixing metal powder and a carrier to create a paste and
applying the paste to an optical element using pad printing,
needles, screen printing, a roller and/or a squeegee tool. The
optical element and paste are thereafter heated and cooled to form
the solid layer of conductive material. In some embodiments, a
stencil may be applied to the optical element before applying the
paste or spraying the molten powder onto the optical element. The
conductive material is therefore deposited in a pattern defined by
the stencil.
[0050] FIG. 2A is a perspective view of apparatus 200 according to
some embodiments, and FIG. 2B is a cross-sectional view of
apparatus 200 as shown in FIG. 2A. Apparatus 200 includes optical
element 220 and conductive material 210 deposited thereon according
to some embodiments of S110. FIGS. 2A and 2B show only a portion of
apparatus 200 in order to illustrate that apparatus 200 may exhibit
any suitable shape or size.
[0051] A thickness of material 210 on optical element 220 need not
be as uniform as shown in FIG. 2B. In addition, a height of
conductive material 210 on various portions of optical element 220
may depend on the technique used to deposit material 210 at
S110.
[0052] Returning to process 100, dielectric material is deposited
on the conductive material at S120. The dielectric material may
comprise cured thick-film photoresist or any other suitable
dielectric material. FIGS. 3A and 3B illustrate dielectric material
230 deposited on conductive material 210 according to some
embodiments of S120.
[0053] Next, at S130, an aperture is created in the dielectric
material using photolithography. Any photolithographic systems and
techniques may be used to create the aperture. According to some
embodiments, photoresist is deposited on the dielectric material,
masked and patterned to define locations corresponding to the
apertures. Photoresist disposed at those locations is removed and
the exposed dielectric material is etched away to expose portions
of the conductive material.
[0054] In a case that the dielectric material itself comprises
photoresist, the dielectric material itself may be masked and
patterned to define the aperture locations. The material at the
locations is then removed to define the apertures. The dielectric
material/photoresist may then require curing according to some
embodiments. The use of photolithography at S130 may provide
desired accuracy in the location of the apertures.
[0055] FIGS. 4A and 4B illustrate apparatus 200 after some
embodiments of S130. Apertures 235 each expose a respective portion
of conductive material 210. Dielectric material 230 may protect
non-exposed portions of conductive material 210 while allowing
soldering of electrical elements to the exposed portions of
conductive material 210. Embodiments are not limited to the
creation of four apertures as depicted in FIG. 4A.
[0056] An electrical contact of a solar cell is coupled to an
exposed portion of the conductive material at S140. The coupling
forms an electrical and a mechanical interconnection between the
conductive material and the solar cell. Various flip-chip bonding
techniques may be employed in some embodiments to couple the
electrical contact of the solar cell to the exposed portion of the
conductive material.
[0057] FIG. 5 is a close-up view of apparatus 200 after S140
according to some embodiments. Solder bumps 505 of solar cell 500
are coupled to conductive material 210 exposed by apertures 325.
Solder bumps 505 are also respectively coupled to unshown terminals
of solar cell 500.
[0058] Solar cell 500 may comprise a solar cell (e.g., a III-V
cell, II-VI cell, etc.) for receiving photons from optical element
220 and generating electrical charge carriers in response thereto.
In this regard, some embodiments include an opening through
dielectric material 230 and conductive material 210 through which
solar cell 500 may receive light from optical element 220. By
accurately fabricating apertures 235, some embodiments provide
accurate placement of an optically-active area of solar cell 500
with respect to the opening. This accurate placement may allow for
a smaller solar cell (i.e., less silicon) than would be required by
designs providing less accurate placement.
[0059] FIG. 6 is a flow diagram of process 600 according to some
embodiments. Process 600 may be performed by any combination of
machine, hardware, software and manual means.
[0060] Process 600 begins at S605, at which an optical element is
obtained. The optical element may be composed of any suitable
material or combination of materials. The optical element may be
created using any combination of devices and systems that is or
becomes known.
[0061] FIG. 7A is a perspective view of optical element 700 created
at S605 according to some embodiments, and FIG. 7B is a
cross-sectional view of element 700. Optical element 700 may be
molded from low-iron glass at S605 using known methods.
Alternatively, separate pieces may be glued or otherwise coupled
together to form element 700. Optical element 700 may comprise an
element of a solar concentrator according to some embodiments.
[0062] Element 700 includes convex surface 710, pedestal 720, and
concave surface 730. The purposes of each portion of element 700
during operation according to some embodiments will become evident
from the description below.
[0063] A reflective material is deposited on the optical element at
S610. The reflective material may be intended to create one or more
mirrored surfaces. Any suitable reflective material may be used,
taking into account factors such as but not limited to the
wavelengths of light to be reflected, bonding of the reflective
material to the optical element, and cost. The reflective material
may be deposited by sputtering, evaporation, liquid deposition,
etc.
[0064] FIGS. 8A and 8B show perspective and cross-sectional views,
respectively, of optical element 700 after some embodiments of
S610. Reflective material 740 is deposited on convex surface 710
and concave surface 730. Reflective material 740 may comprise
sputtered silver or aluminum. The vertical and horizontal surfaces
of pedestal 720 may be masked at S610 such that reflective material
740 is not deposited thereon, or otherwise treated to remove any
reflective material 740 that is deposited thereon.
[0065] Next, at S615, an electrical insulator is deposited on the
reflective material. The insulator may comprise any suitable
insulator or insulators. Non-exhaustive examples include polymers,
dielectrics, polyester, epoxy and polyurethane. The insulator may
be deposited using any process that is or becomes known. In some
embodiments, the insulator is powder-coated onto the optical
element.
[0066] Some embodiments of S615 are depicted in FIGS. 9A and 9B.
Insulator 750 is deposited on convex surface 710 or, more
particularly, on reflective material 740. Again, S615 is executed
such that insulator 750 is not deposited on the vertical and
horizontal surfaces of pedestal 720. According to the illustrated
embodiment, insulator 750 is not deposited on concave surface 730
(i.e., on reflective material 740 deposited on concave surface
730).
[0067] Returning to process 600, a pattern of conductive material
is deposited on the insulator using a thick film process at S620.
The conductive material may be composed of any combination of one
or more materials (e.g., nickel, copper), and may be deposited
using the thermal spraying, paste-based, or other techniques
described above. A stencil may be employed at S620 as also
described.
[0068] FIG. 10A is a perspective view and FIG. 10B is a
cross-sectional view of optical element 700 after S620 according to
some embodiments. Conductive material 760 covers pedestal 720 and
portions of insulator 750. Conductive material 770, which may be
different from or identical to material 760, also covers portions
of insulator 750. Conductive material 760 and conductive material
770 define a gap to facilitate electrical isolation from one
another. Although conductive materials 760 and 770 appear to extend
to a uniform height above element 700, this height need not be
uniform.
[0069] Embodiments of S620 such as that depicted in FIGS. 10A and
10B may include placing a stencil in the shape of the illustrated
gap on electrical isolator 750 and depositing conductive material
760 and 770 where shown and on the stencil. The stencil is then
removed to result in the apparatus of FIGS. 10A and 10B.
[0070] Conductive materials 760 and 770 may create a conductive
path for electrical current generated by a photovoltaic (solar)
cell coupled to element 700. Conductive material 760 and conductive
material 770 may also, as described in U.S. Patent Application
Publication No. 2006/0231133, electrically link solar cells of
adjacent solar concentrators in a solar concentrator array.
[0071] Aperture 765 may comprise an exit window for light entering
element 700. Aperture 765 may be formed by masking a corresponding
area of pedestal 720 prior to depositing conductive material 760.
Such masking may comprise depositing a liquid or solid mask on
pedestal 720 prior to S620 and removing (i.e., peeling or
dissolving) the mask thereafter. Some embodiments employ
photolithography to define aperture 765 after depositing conductive
material on the entirety of pedestal 720 at S620.
[0072] At S625, dielectric material is deposited on the conductive
material. Any suitable material of any suitable thickness may be
deposited at S640 in any suitable manner. FIGS. 11A and 11B
illustrate deposited dielectric material 780 according to some
embodiments of S625. Portions of dielectric material 780 are shown
sunken into aperture 765, but an upper surface of dielectric
material 780 may be substantially flat in some embodiments.
[0073] Thin-film photoresist is deposited on the dielectric
material at S630. The close-up perspective view of FIG. 12A
illustrates photoresist 790 upon dielectric material 780. FIG. 11B
is a cross-sectional view illustrating the several layers upon
optical element 700 after S630.
[0074] The deposited photoresist is masked at S635 in accordance
with a desired location of an aperture. Masking at S635 may proceed
using known techniques and may depend on a desired accuracy,
wavelength of exposing light, type of photoresist, etc. The masked
photoresist is then exposed to light at S640 and, depending on
whether the photoresist is "negative" or "positive", exposed or
unexposed portions of the photoresist are removed at S645.
[0075] FIG. 13A shows photoresist 790 with several portions removed
therefrom. Removal of the portions exposes portions 785 of
dielectric material 180. Next, at S650, exposed portions 785 of the
dielectric material are etched or otherwise removed to expose
portions of the conductive material. FIGS. 14A and 14B show
apertures 787 defined by dielectric material 780 after S650.
Portions of conductive material 760 are exposed through apertures
787.
[0076] An electrical contact of a solar cell is coupled to an
exposed portion of the conductive material at S6505. The electrical
contact may be coupled such that an optically-active area of the
solar cell is aligned with aperture 765. The electrical contact may
comprise a solder bump, and any number of intermediate conductive
elements such as various layers of bonding pads may be used to
couple the electrical contact to the exposed portion.
[0077] FIG. 15 shows solder bumps 805 of solar cell 800 coupled to
conductive material 760 exposed by apertures 787. Solar cell 800
includes window 810 for receiving light into an optically-active
area of cell 800. Increasing the accuracy of alignment between
window 810 and aperture 765 may allow for a reduction in the size
of the optically-active area. Some embodiments provide improved
accuracy by defining the exposed portions of the conductive
material using thin film techniques and by coupling the solar cell
to the exposed portions using flip-chip bonding. Some embodiments
additionally provide reduced fabrication cost by fabricating the
conductive material layer using thick film techniques.
[0078] Apparatus 700 of FIG. 15 may generally operate in accordance
with the description of aforementioned U.S. Patent Application
Publication No. 2006/0231133. With reference to FIG. 15, solar rays
enter surface 798 and are reflected by reflective material 740
disposed on convex surface 710. The rays are reflected toward
reflective material 740 on concave surface 730, and are thereafter
reflected toward aperture 765. The reflected rays pass through
aperture 765 and are received by window 810 of solar cell 800.
Those skilled in the art of optics will recognize that combinations
of one or more other surface shapes may be utilized to concentrate
solar rays onto a solar cell.
[0079] Solar cell 800 receives a substantial portion of the photon
energy received at surface 798 and generates electrical current in
response to the received photon energy. The electrical current may
be passed to external circuitry (and/or to similar
serially-connected apparatuses) through conductive material 760 and
conductive material 770. In this regard, solar cell 800 may also
comprise an electrical contact electrically coupled to conductive
material 770. Such a contact would exhibit a polarity opposite to
the polarity of the contacts to which solder bumps 805 are
coupled.
[0080] The several embodiments described herein are solely for the
purpose of illustration. Embodiments may include any currently or
hereafter-known versions of the elements described herein.
Therefore, persons in the art will recognize from this description
that other embodiments may be practiced with various modifications
and alterations.
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