U.S. patent application number 11/708823 was filed with the patent office on 2007-11-29 for camera device, method of manufacturing a camera device, wafer scale package.
Invention is credited to Leendert De Bruin, Gerardus Maria Dohmen, Erik Harold Groot, Aloysius Franciscus Maria Sander, Anton Petrus Maria Van Arendonk, Arjen Gerben Van Der Sijde, Edwin Maria Wolterink.
Application Number | 20070275505 11/708823 |
Document ID | / |
Family ID | 32033880 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070275505 |
Kind Code |
A1 |
Wolterink; Edwin Maria ; et
al. |
November 29, 2007 |
Camera device, method of manufacturing a camera device, wafer scale
package
Abstract
The invention relates to a camera device and a method for
manufacturing such a device. The camera device comprises an image
capturing element, a lens element for imaging an object at the
image capturing element and a spacer means for maintaining a
predetermined distance along the main optical axis through the lens
and the image capturing element, and lens substrate for carrying
the lens wherein the spacer means comprises an adhesive layer. This
enables a mass manufacturing process wherein parts of the
individual camera elements can be manufactured in manifold on
different substrates, after which the different substrates are
stacked, aligned and joined via adhesive layers. In the
manufacturing process the different distances between the plates
and the wafers are adjusted and maintained via the spacer means
comprising the adhesive layers. From the stack individual camera
devices are sawn out.
Inventors: |
Wolterink; Edwin Maria;
(Eindhoven, NL) ; Dohmen; Gerardus Maria;
(Eindhoven, NL) ; Sander; Aloysius Franciscus Maria;
(Eindhoven, NL) ; Van Der Sijde; Arjen Gerben;
(Eindhoven, NL) ; De Bruin; Leendert; (Eindhoven,
NL) ; Groot; Erik Harold; (Eindhoven, NL) ;
Van Arendonk; Anton Petrus Maria; (Eindhoven, NL) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Family ID: |
32033880 |
Appl. No.: |
11/708823 |
Filed: |
February 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10527778 |
Mar 14, 2005 |
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PCT/IB03/03920 |
Sep 15, 2003 |
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11708823 |
Feb 21, 2007 |
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Current U.S.
Class: |
438/118 ;
257/E21.001; 348/E5.028 |
Current CPC
Class: |
H04N 5/2257 20130101;
G02B 13/006 20130101; H04N 5/2254 20130101; G02B 13/0085 20130101;
H01L 27/14627 20130101; H01L 27/14618 20130101; G02B 13/001
20130101; H01L 27/14625 20130101; H01L 2924/0002 20130101; H01L
2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
438/118 ;
257/E21.001 |
International
Class: |
H01L 21/00 20060101
H01L021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2002 |
EP |
02078852.7 |
Oct 1, 2002 |
EP |
02079107.5 |
Oct 1, 2002 |
EP |
02079106.7 |
Claims
1. (canceled)
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. (canceled)
0. (canceled)
10. (canceled)
11. (canceled)
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. A method for manufacturing a camera device, characterized by
the steps of providing a lens substrate comprising a plurality of
lens elements, the lens substrate comprising an adhesive layer;
stacking the lens substrate and a base substrate comprising a
plurality of image capturing elements; aligning the lens substrate
and the base substrate along main optical axes through respective
lens elements and associated image capturing elements; setting the
distance between the lens elements and the associated image
capturing elements along the main optical axes through the lens
elements and the associated image capturing elements; hardening the
adhesive layer; and separating camera devices from the stack of the
lens substrate and the base substrate.
18. (canceled)
19. (canceled)
20. A method of manufacturing a camera device in accordance with
claim 17, wherein: said adhesive layer comprises an ultra-violet
curing resin.
21. A method of manufacturing a camera device in accordance with
claim 17, wherein: said adhesive layers comprises a
thermo-hardening resin.
22. A method of manufacturing a camera device in accordance with
claim 17, including: providing the lens substrate with an infra-red
reflecting layer.
23. A method of manufacturing a camera device in accordance with
claim 17, including: providing the lens substrate with an
anti-reflection layer.
24. A method of manufacturing a camera device in accordance with
claim 17, including: providing spacer means between the lens
substrate and the base substrate in the form of a spacer substrate,
said spacer substrate comprising holes coaxially positioned
relative to the main optical axes of the lens elements and the
associated image capturing elements.
25. A method of manufacturing a camera device in accordance with
claim 17, including: providing spacer means between the lens
substrate and the base substrate in the form of a cover substrate,
wherein said cover substrate comprises a second lens substrate
having a plurality of second lens elements for each projecting an
object onto a respective image capturing element, the main optical
axes of the lens elements coinciding with the main optical axes of
the second lens elements.
26. A method of manufacturing a camera device in accordance with
claim 17, wherein: each of the lens elements is of a replication
type.
27. A method of manufacturing a camera device in accordance with
claim 26, wherein: each lens element is formed as a convexity in
the lens substrate.
28. A method of manufacturing a camera device in accordance with
claim 26, wherein: each lens element is formed as a concavity in
the lens substrate.
Description
[0001] The invention relates to a camera device comprising an image
capturing element, a lens element for projecting an object on the
image capturing element, a spacer means for maintaining a
predetermined distance between the lens and the image capturing
element, and a lens substrate for carrying the lens.
[0002] The invention also relates to a method for manufacturing a
camera device, a wafer scale package comprising a base substrate
having a plurality of image capturing elements, and an optical
assembly for use in a process for manufacturing a camera
device.
[0003] Camera devices of this type are used in, for instance small
portable devices such as mobile telephones, personal digital
assistants (PDAs) and laptop computers.
[0004] A camera device as mentioned in the opening paragraph is
disclosed in the Japanese patent application published under number
JP-2002/139662. The known camera device comprises an image pick-up
element mounted on a substrate, and a lens support carrying one or
more lenses. The lens support is integrally formed with the lens
and is fastened to the image pick-up element whereby the lens
support takes care of an accurate position in the direction of a
main optical axis through the lenses on the image pick-up element.
In a manufacturing process the individual image pick-up element,
lens support, and lens are stacked and joined together. In order to
obtain a high-quality image of an object on the image pick-up
element, the dimensions of the lens support in the direction of the
main optical axis should have a high accuracy. Furthermore
positioning of these parts relative to each other should be
accurate.
[0005] A disadvantage of the known camera device is that the
manufacturing process each lens support has to be adjusted
separately relative to the image pick-up element in each camera
device, so there is little possibility to manufacture the known
camera device in an efficient mass production process while
maintaining a high positioning accuracy.
[0006] It is inter alia an object of the invention to provide a
camera device of the type mentioned in the opening paragraph,
having an increased capability for an efficient mass manufacturing
process with a high positioning accuracy.
[0007] To this end the invention provides camera device as defined
in the opening paragraph which is characterized in that the spacer
means comprises an adhesive layer.
[0008] In this arrangement the lens substrate including the lens
element and the spacer means comprising the adhesive layer, can be
positioned and aligned along the main optical axis through the lens
element and the image capturing element, after which a
predetermined distance is set between the lens element and the
image capturing device. After hardening the adhesive layer this
predetermined distance is maintained by the spacer means. This
arrangement provides increased capabilities for mass manufacturing
wherein a plurality of image capturing elements, lens elements and
spacer means can be manufactured on a base substrate comprising the
imaging elements and a lens substrate respectively, whereby the
base substrate and the lens substrate are stacked and joined with a
high accuracy and the individual camera devices are separated from
the stack. The hardening of the adhesive layer can be performed in
case of an ultra-violet curable adhesive by UV radiation or in case
of a thermo-hardening adhesive by heating the adhesive layer.
[0009] U.S. Pat. No. 6,285,064 introduces a wafer scale package for
solid state image sensor integrated circuits, whereby arrays of
micro lenses are placed on top of a wafer having the image sensors
formed thereon. An adhesive matrix is placed atop of the wafer. The
adhesive matrix has openings that align with the micro lens arrays
on top of the wafer. A cover glass is then placed over the adhesive
and the adhesive is activated to secure the cover glass to the
wafer. Because the adhesive has openings above the micro lensed
portion distortion or reduction of the lens effect by the adhesive
shall be avoided.
[0010] It is a further object of the invention to provide a method
for an efficient mass production process of a camera device. This
object is achieved by a method for manufacturing a camera device,
characterized by the steps of
[0011] providing a lens substrate comprising a plurality of lens
elements, the lens substrate comprising an adhesive layer;
[0012] stacking the lens substrate and a base substrate comprising
a plurality of image capturing elements;
[0013] aligning the lens substrate and the base substrate along
main optical axes through respective lens elements and associated
image capturing elements;
[0014] setting the distance between the lens elements and the
associated image capturing elements along the main optical axes
through the lens elements and the associated image capturing
elements;
[0015] hardening the adhesive layer; and
[0016] separating camera devices from the stack of the lens
substrate and the base substrate.
[0017] In this process the camera devices are manufactured by
stacking a lens substrate comprising a plurality of lens elements,
spacer means in the form of a spacer substrate and a base substrate
containing a plurality of image capturing elements. The
predetermined distances along the optical axis through the
individual lens elements and the associated image capturing
elements between the different substrates can be accurately
adjusted after the stacking of the substrates and maintained by
hardening of the adhesive layer between the different substrates.
After completing the stack, the individual camera devices can be
separated from the stack. This process yields relatively cheap
camera devices which are suitable for use in small electronic
equipment, such as mobile phones and personal digital
assistants.
[0018] It is a further object of the invention to provide a wafer
scale package for an efficient mass production of a camera device.
This object is achieved by a wafer scale package comprising a base
substrate having a plurality of image capturing elements,
characterized in that it further comprises a lens substrate having
a plurality of lens elements associated with respective image
capturing elements, and a spacer means for maintaining a
predetermined distance between the lens substrate and the base
substrate, whereby the position of the lens substrate relative to
the base substrate is fixated by means of an adhesive layer.
[0019] In this wafer scale package the lenses are already aligned
relative to the corresponding image capturing elements and the
distance between the lenses and the corresponding image capturing
elements is accurately adjusted. In this way it is not required to
position individual lens elements relative to corresponding
individual image capturing elements, thereby simplifying the
manufacturing of camera devices.
[0020] It is a further object of the invention to provide an
optical assembly for an efficient mass production of a camera
device. This object is achieved by An optical assembly for use in a
process for manufacturing a camera device according to the
invention, characterized in that it comprises a lens substrate
having a plurality of lens elements.
[0021] By stacking the optical assembly and a base substrate
comprising a image capturing elements corresponding to the
plurality of lens elements it is possible to position the lens
elements relatively to the image capturing elements for all lens
elements simultaneously. In this way it is not necessary to
position individual lens elements relative to individual image
capturing elements in a later stage of production.
[0022] Preferably the optical assembly has area dimensions
corresponding to the area dimensions of the base substrate
comprising the image capturing elements.
[0023] In embodiments the adhesive layer comprises an ultra-violet
curing resin or a thermo-hardening resin.
[0024] In a further embodiment the adhesive layer has the shape of
a rim situated outside the projection of the hole on the spacer
means, co-axially positioned with the main optical axis of the lens
element. In this way, no adhesive material is in the optical path
between the lens element and the image capturing element.
[0025] In a further embodiment the spacer means comprises a cover
substrate and a spacer substrate. The cover substrate protects the
image capturing element against possible damage during further
manufacturing process steps.
[0026] In a further embodiment the spacer substrate comprises a
hole coaxially positioned relative to a main optical axis of the
lens element whereby the side of the hole is provided with an
anti-reflection layer. This arrangement reduces reflection within
the camera device, thereby enhancing its performance.
[0027] In a further embodiment the adhesive layer can be provided
between the image capturing element and the spacer substrate; and
also between the spacer substrate and the cover substrate. This
arrangement enables accurate adjustment after each separate step of
stacking.
[0028] In a further embodiment the lens element is of a replication
type. These replication type lenses enable manufacturing of high
quality lenses at low costs. Suitable materials for manufacturing
replication type lenses are in principle all monomers with a group
that can be polymerized.
[0029] In a further embodiment the lens element is formed as a
convexity in the lens substrate. This simplifies the manufacturing
of the lens elements.
[0030] In a further embodiment the lens element is formed as a
concavity in the lens substrate. In this arrangement the lens
substrate can be part of the spacer means. In this way larger
distances between the lens and the image capturing element can be
obtained by increasing the thickness of the lens substrate, without
increasing the complexity of the manufacturing process by
introducing a separate spacer substrate.
[0031] In a further embodiment the lens substrate is provided with
a through hole whereby the lens element is located within the
through hole. In this way more flexibility is provided in the shape
of the lens and in the distance between the lens and the image
capturing element.
[0032] In a further embodiment the lens substrate is provided with
an infra-red reflection layer. Solid state image capturing elements
are sensitive to infra-red radiation. By cutting off this infra-red
range of the spectrum, the sensitivity of the camera device for
infrared radiation is reduced.
[0033] In a further embodiment the lens substrate is provided with
an anti-reflection layer. This arrangement avoids reflection in the
camera device.
[0034] These and other aspects of the invention are apparent from
and will be elucidated with reference to the embodiments described
hereinafter.
[0035] In the drawings:
[0036] FIG. 1 is a cross-sectional view of a first embodiment of a
camera device,
[0037] FIG. 2 is a cross-sectional view of a second embodiment of a
camera device,
[0038] FIG. 3 shows a stack of wafer plates obtained after several
successive manufacturing steps, of the camera device before dicing
out the camera devices,
[0039] FIG. 4 shows a manufacturing process flow chart of the
camera device;
[0040] FIG. 5 shows a step of dicing the stack of wafer plates.
[0041] FIGS. 6a to 6d show, in slice planes, different arrangements
for a wafer scale package comprising solid-state image sensors,
according to the principle of the present invention;
[0042] FIGS. 7a to 7d represent simulations of different optical
systems for use in a camera device, wafer scale package, or optical
module according to the invention;
[0043] FIGS. 8a to 8e show several steps of the manufacturing of a
further embodiment of a camera device according to the
invention.
[0044] FIGS. 9a to 9f show, in slice planes, several embodiments of
an optical assembly according to the invention.
[0045] FIGS. 10a to 10d show, in slice planes, further embodiments
of an optical assembly according to the invention.
[0046] The Figures are schematic and not drawn to scale, and, in
general, like reference numerals refer to like parts.
[0047] FIG. 1 schematically shows a first embodiment of a camera
device. The camera device 101 comprises an image capturing element
103, a micro spacer plate 105 glued to the image capturing element,
a cover plate 107 glued to the micro spacer plate 105 and a lens
substrate 109 provided with a lens 111. The image capturing element
is a Charge Coupled imaging Device (CCD) or a CMOS imaging device.
In general such an image capturing element is referred to as a
solid-state image sensor (SSIS). The micro spacer plate 105 is
provided with a hole for passing image forming light rays from the
lens element 111 to the image capturing element 103. Preferably, an
infra-red reflection coating 119 is provided between the lens
substrate 109 and the cover plate 107; and an anti-reflex coating
121 is provided over the lens substrate 109 and the lens element
111. A first adhesive layer 113 of approximately 10 .mu.m thickness
is present between the micro space plate 105 and the image
capturing element 103. A second adhesive layer 115 of approximately
100 .mu.m thickness is present between the cover plate 107 and the
micro spacer plate 105 and a third adhesive layer 117 of
approximately 10 .mu.m thickness is present between the lens
substrate 109 and the cover plate 107. Preferably, the adhesive
layers 113, 115, 117 are rim-shaped, the adhesive material being
present outside an area coinciding with the projection of the
circumference of the lens element 111 on the surfaces of the
micro-spacer plate 105 and the cover plate 107.
[0048] The thickness of the micro-space plate 105 is for example
0.4 mm. The thickness of the cover plate is 0.4 mm and the
thickness of the lens substrate plate is for example 0.4 mm. Each
adhesive layer 113, 115, 117 maintains the distance between the
different plates to a predetermined distance with an accuracy of
typically 5 .mu.m. In the camera device 101 the spacer means is
thus formed by the micro-spacer plate 105, the cover plate 107 and
the adhesive layers 113, 115, 117.
[0049] To prevent ghost imaging on the image capturing element 103
it may be advantageous to provide an anti-reflection layer on the
side wall of the micro-spacer plate 105, thereby by preventing
unwanted reflections of light within the camera device 101. Such an
anti-reflection layer can be provided for instance by coating the
side wall of the micro-spacer plate 105 with a low reflecting
material, for instance with black resist. The coating may be
applied by means of spraying.
[0050] FIG. 2 shows a second embodiment of a camera device. This
camera device 110 comprises an optical system of two lens elements
111, 127. An advantage of the two-lens optical systems is that a
relatively strong lens operation is obtained without much
aberrations.
[0051] Parts in FIG. 2 assigned the same number as in FIG. 1
correspond to the same elements. Furthermore, FIG. 2 shows a second
lens substrate 125 stacked on a second spacer place 123 and the
first lens substrate 109 respectively, aligned along the main
optical axis through the second lens element 127, the first lens
element 111 and the image capturing element 103 and joined by
adhesive layers 129, 131. Preferably, a diaphragm 133 is formed
from an aluminum layer provided with a hole co-axially positioned
with the main optical axis of the lenses 111, 127.
[0052] To prevent ghost imaging on the image capturing element 103
it may be advantageous to provide an anti-reflection layer on the
side wall of the micro-spacer plate 105 and/or on the side wall of
the second spacer plate 123, thereby by preventing unwanted
reflections of light within the camera device 110.
[0053] A manufacturing method for these camera devices comprises
wafer scale manufacturing steps because multiple image capturing
elements are manufactured and obtained on a substrate, for example,
a silicon wafer of approximately 20.32 cm diameter (8''). Also the
spacer means and lens elements can be manufactured in manifold on
substrates. FIG. 3 shows an exploded view of a stack of substrates
before the individual camera devices 110 are diced out. This stack
130 comprises a base substrate 134 comprising the silicon wafer 135
containing image capturing elements 103, a micro-spacer wafer 137
containing micro-spacer elements 105, a cover wafer 139 and a first
lens substrate 141 containing lenses 109. All these elements are
available on a wafer dimension scale. Furthermore, FIG. 3 shows a
second spacer wafer 143, a second lens substrate 145 and a further
cover wafer 147, necessary to obtain a camera device provided with
an optical system of two lenses.
[0054] FIG. 4 shows a process flow chart 140 of a method for
manufacturing camera devices. In a process step 120 the first lens
substrate 141 is manufactured by providing an infra-red coating 119
on a glass substrate, followed by a process step P21 of forming the
lens elements 111 on the glass substrate via a conventional
replication process. In a further process step P22 the first lens
substrate 141 is provided with an anti-reflex coating 121.
[0055] The base substrate 134 is manufactured in the following
process steps. In a process step P10 a micro-spacer wafer 137 is
manufactured by etching holes in a glass substrate of wafer size
dimension for example 20.32 cm. Alternatives for etching in this
process step P10 are: laser cutting, powder blasting and ultrasonic
drilling. All these techniques are well known to a person skilled
in the art. In a subsequent step, process step P12, the
micro-spacer wafer 137 and the silicon wafer 135 containing the
image capturing elements, are provided with an adhesive layer via
screen printing, or alternatively, spray coating. The adhesive
layer may consist of for example an ultra-violet curable resin.
Furthermore, the micro-spacer wafer 137 and the cover wafer 139 are
aligned and the distance along the main optical axis between the
cover plate wafer the holes of the micro-spacer wafer 137 and the
image surface of the associated image capturing elements 103 of the
silicon wafer 135 is set to a predetermined value of, for example,
900.+-.5 .mu.m, after which the adhesive layer is cured by
ultra-violet radiation. The hardened adhesive layer 115 maintains
the adjusted distance. The joined wafers 135, 137, 139 form the
base substrate 134 containing the image capturing elements 103.
[0056] In a subsequent process step P14 the base substrate 134 and
the lens substrate 141 are aligned, set to, a predetermined
distance of, for example 10 .mu.m; and joined together via an
ultra-violet (UV) curable adhesive layer 117. In a further
subsequent step P15 the individual camera devices are separated,
for example, by sawing.
[0057] In order to obtain a camera device 110 comprising an optical
system of two lens elements 111, 127 some further process steps
P40, P41 and P31 are required. In process step P30 a second spacer
wafer 143 is provided with holes for image forming rays to pass
through. In the process step P40 the lenses 127 are formed on the
second lens substrate via a replication process. Preferably, in a
subsequent process step P41 a diaphragm is provided on the lens
127. The diaphragm is formed by an aluminum layer with a circular
hole coaxially positioned relative to the main optical axis of the
lens system. In a subsequent joining step P31 the second lens
substrate plate 145 and the second spacer wafer 143 are aligned,
set to a predetermined distance of for example 1.67 mm; and joined
by an ultra-violet curable adhesive layer 131 of approximately 100
.mu.m. In a subsequent process step P23, the sub-assembly of second
lens substrate plate 145 and the second spacer plate 143 is
aligned, set to a predetermined distance of for example 121 mm to
the first lens substrate plate 141, and joined by an ultra-violet
curable adhesive layer 129 of 10 .mu.m.
[0058] In the process step P14 this lens substrate assembly 44 and
the base substrate sub-assembly 142 of process step P13 are
aligned, set to a predetermined distance and joined by an
ultra-violet curable adhesive layer 129. Preferably, in this
process step a third spacer plate 146 and a second cover plate 147
are stacked on the second lens substrate 145 by an ultra-violet
curable layer. In a separating step P15 the camera devices 110 are
sawn out, or separated in another known way, of the assembled stack
150 as diagrammatically shown in FIG. 5. The assembled stack 150 is
sawn via a dicing lane 152. The width of the dicing lane is for
example approximately 230 .mu.m. It may be advantageous to apply a
thermo-hardening adhesive instead of a ultra-violet curing
adhesive.
[0059] It will be obvious that many variations are possible within
the scope of the invention without departing from the scope of the
appended claims.
[0060] In FIGS. 6a to 6d are shown, in slice planes, different
arrangements for a wafer scale package comprising solid state image
sensors (SSIS), according to the principle of the present
invention. All through the FIGS. 6a to 6d there is a silicon wafer
211, comprising an array of SSIS dies (not illustrated in FIGS. 6a
to 6d) and a covering glass layer 231, preferable made of an IR
glass. For better illustration, there is only shown a section of
the whole wafer, which is indicated by the dotted line L on the
left side of each FIG. 6a to 6d. It will be noted that within the
arrangement of the silicon wafer 211 and the glass layer 231, micro
lenses may be attached to the photosensitive area of the SSIS dies.
As to the performance of the camera devices that are obtained by
separating the wafer scale package, this will be referred to in
FIGS. 7a to 7d.
[0061] The wafer scale package in FIG. 6a only comprises a first
glass layer 231 and a second glass layer providing convex lenses
250 orientated away from surface of the silicon wafer 211. In FIG.
6b there is the only change in comparison to FIG. 6a that a spacer
layer 222 has been inserted between a first transparent layer 231
and a second transparent layer 240 containing the lenses 250. As to
FIG. 2c, there is a further minor change with respect to FIG. 6b,
here an additional glass layer 242 comprising lenses 52 has been
inserted between the spacer layer 222 and the first glass layer
231. In this embodiment, there is an air gap between the two lenses
250, 252 of the wafer scale package. Finally, FIG. 6d shows an
arrangement, again in comparison to FIG. 6b, wherein a additional
glass layer 244 with lenses 254 is arranged between the spacer
layer 222 and the glass layer 240.
[0062] Now reference is made to FIGS. 7a to 7d, here the
performance of some examples for camera devices, wafer scale
packages, and optical modules according to the present invention
are illustrated by way of simulation diagrams. The simulations give
results according to performance and dimensions of a camera device
according to the present invention. All simulation diagrams read as
follows: starting from the left, i.e. the real image which is to be
projected by the optical system, there are light rays, which are
depicted as lines, going through the optical system and crossing
each other behind the optical system. The cross points of these
simulated light rays could be connected by a drawing line, this
would lead to the ideal image plane wherein the real image would be
projected without error. However, since the photosensitive area of
an SSIS is flat, the optical system has to be adapted to a flat
photosensitive area as image plane. Looking at FIG. 7a shows that
an optical system with only one lens has a very curved image plane
and therefore, produces increasingly low performance towards the
edges of the image plane. FIGS. 7b to 7d display the advantage of a
second lens in the optical system, since both lenses work together
as to focus and as to flattening of the image plane and thus, the
image plane is more adapted to the photosensitive area. The
arrangement in FIG. 7b has as an advantage that it is very low in
height. This is because of the fact, that a large angle for the
traveling light can be used in the air cavity between the two
lenses.
[0063] Now reference is made to FIGS. 8a to 8e, where several steps
of the manufacturing process of a further embodiment of the present
invention are illustrated. As can be seen from top of FIG. 8a, a
micro-spacer layer 225 for the micro lenses (not illustrated) is
mounted on the top side of a silicon wafer 215 comprising
solid-state image sensors. In a next step a cover glass layer 235
is attached to the micro-spacer layer 225. Onto the cover glass
layer 235 is an IR glass layer 236 mounted. Hereafter follows a
further step for installing an optical system for the SSIS on wafer
scale. On top of the IR glass layer 236 a wafer level lens holder
or lens substrate 260 with cavities 262 for lenses is placed. This
leads to FIG. 8b. Now referring to FIG. 8c, after the wafer level
lens holder 260 has been glued to the IR glass layer 236, the
lenses 270 are mounted into the cavities 262 of the wafer level
lens holders 260. In FIG. 8d can be seen that the camera devices
are separated after mounting of the lenses 270. In a next step such
a camera device 295 can be installed onto a flex foil 290 for
interconnection. Furthermore it may be advantageous to provide a
sunshade 280. This sunshade 280 can be mounted before installation
into an application or can be a part of a housing in which the
camera device 295 can be installed.
[0064] FIGS. 9a to 9f show, in slice planes, several embodiments of
an optical assembly according to the invention. The shown optical
assemblies comprise a substrate having a plurality of lens
elements. The optical assemblies are to be used in a manufacturing
process of camera devices. This can be, for instance, a process
similar to the process shown in FIG. 4. In such a process the
optical assembly is preferably stacked to a base substrate
comprising a plurality of image capturing elements corresponding to
the lens elements. Preferably an adhesive is used to join the
optical assembly and the base substrate. After the distance has
been set between the respective lens elements and corresponding
image capturing elements, and the lens substrate and the base
substrate have been aligned relatively to each other, the adhesive
is cured. This results in a wafer scale package similar to those
shown in FIG. 3, FIG. 5, and FIG. 6. Alternatively, the optical
assembly may be separated into individual lens modules which are
stacked to individual image capturing elements.
[0065] The optical assemblies shown in FIGS. 9a to 9f are
manufactured by means of a replication process. In such a process
the lenses are usually made in whole or in part of polymers or
curable liquids that are optically transparent. The lens substrate
is usually made of an optically transparent material such as for
example glass, plastic, resin, or quartz.
[0066] FIG. 9a shows a cross section of an optical assembly 310
comprising a plurality of replication type positive or convex lens
elements 311 formed on a lens substrate 312. The lens elements may
be spherical, aspherical, or anamorphic. FIG. 9a also shows an
individual lens module 315, comprising a replication type positive
lens element 316 on a substrate 317, that is obtained by separating
the optical assembly 310 along the lines 313. For separation, known
methods, as for instance dicing can be used.
[0067] FIG. 9b shows a cross section of an optical assembly 320
comprising a plurality of replication type negative or concave lens
elements 321 formed on a lens substrate 322. The lens elements may
be spherical, aspherical, or anamorphic. FIG. 9b also shows an
individual lens module 325, comprising a replication type negative
lens element 326 on a substrate 327, that is obtained by separating
the optical assembly 320 along the lines 323.
[0068] FIG. 9c shows a cross section of an optical assembly 330
comprising a plurality of positive-negative replication type lenses
formed in through holes in the lens substrate 333. FIG. 9c also
shows an individual lens module 335, comprising a replication type
positive-negative lens element 336 formed in a through hole in a
substrate 337, that is obtained by separating the optical assembly
330 along the lines 333. In this case the substrate 331, 337 does
not need to be transparent. This may be advantageous in preventing
unwanted reflection of light in a camera device in which the
optical module is used. A further advantage of the optical assembly
330 and the optical module 335 is the by combining a positive lens
and a negative lens in this way the resulting stack height may be
reduced as compared with the optical module and the optical
assembly shown in FIG. 9d.
[0069] FIG. 9d shows a cross section of an optical assembly 340
comprising a plurality of positive replication type lenses 341 and
corresponding negative replication type lenses 342, both on
opposite sides of a lens substrate 343. FIG. 9d also shows an
individual lens module 345, comprising a replication type positive
lens element 346 and a corresponding negative replication type lens
element 348 formed on opposite sides of a lens substrate 347, that
is obtained by separating the optical assembly 340 along the lines
343.
[0070] FIG. 9e shows a cross section of an optical assembly 350
comprising a plurality of first replication type positive lenses
351 formed on a first lens substrate 352, separated from a
plurality of corresponding second replication type positive lenses
354 formed on a second lens substrate 355 by means of a spacer
substrate 353 having through holes coaxially aligned with the
optical axes through respective first lenses 351 and second lenses
354. By changing the thickness of the spacer substrate 353 the
distance between the first lenses 351 and the corresponding second
lenses 354 is changed. FIG. 9e also shows a lens module 360 that is
obtained by separating the optical assembly 350 along the lines
356. It comprises a first positive replication type lens element
361 formed on a first lens substrate 362, which is separated from a
corresponding second lens element 364 formed on a second lens
substrate 364 by means of a spacer substrate 363 having a through
hole coaxially aligned with the optical axis through the first lens
element 361 and the second lens element 364.
[0071] FIG. 9f shows a cross section of an optical assembly 370
comprising a plurality of first replication type positive lenses
371 and a plurality of corresponding second replication type
negative lenses 373 formed on opposite sides of a first lens
substrate 372, joined with a plurality of corresponding third
replication type positive lenses 374 formed on a second lens
substrate 375 by means of a spacer layer of adhesive material (not
shown). The respective first lenses 371, and corresponding second
lenses 373 and third lenses 375 are aligned along the same optical
axes. FIG. 9f also shows a lens module 380 that is obtained by
separating the optical assembly 370 along the lines 376. It
comprises a first positive replication type lens element 381 and a
corresponding second negative replication type lens 383 formed on
opposite sides of a first lens substrate 382, which is joined with
a corresponding third positive replication type lens element 384
formed on a second lens substrate 384. The first lens element 381,
the second lens element 383, and the third lens element 384 have a
common optical axis. An advantage of combining the second lens
element 383 and the third lens element 384 is that the need of a
separate spacer substrate may be circumvented.
[0072] FIGS. 10a to 10d show, in slice planes, further embodiments
of an optical assembly according to the invention. In a similar way
as the optical assemblies shown in FIGS. 9a to 9e these optical
assemblies are used in the manufacturing of a camera device. The
main difference with the optical assemblies shown in FIGS. 9a to 9e
is that the optical assemblies shown in FIGS. 10a to 10d comprise
pre-shaped substrates that are optically transparent. Such
pre-shaped substrates can be made for instance by hot-forming of a
suitable transparent material. This involves heating the substrate
material and forming it by using a mould. Suitable substrate
materials are, for instance, glass, quartz, and suitable
transparent plastics.
[0073] FIG. 10a shows an optical assembly 400 comprising a
pre-shaped substrate 401 having a plurality of convexities 402. The
convexity function as positive lens elements. To enhance their
functioning as lens elements The convexities are covered by a
correction layer of replication type material 403. FIG. 10a also
shows an individual optical module 405 that is obtained by
separating the optical assembly 400 along the lines 404.
[0074] FIG. 10b shows a pre-shaped substrate 411 comprising a
plurality of positive replication type lens elements 412 formed on
one side of a pre-shaped substrate 411 and a plurality of
depressions or recessed areas 413 corresponding to the lens
elements 411 at the other side of the substrate 411. An advantage
of the shown pre-shaped substrate is that it integrates the
functionality of a lens substrate, as shown in FIGS. 9a to 9e, and
the functionality of a spacer layer. In this way the number of
components making up a camera device may be reduced, resulting in a
more simple assembly and/or a more camera device having a lens
system that is more accurately aligned with the image capturing
element. FIG. 10b also shows an individual optical module 415 that
is obtained by separating the optical assembly 410 along the lines
414.
[0075] FIG. 10c shows an optical assembly 420 comprising a
pre-shaped substrate 421 having a plurality of convexities 422
formed at one side of a substrate 421 and a plurality of
depressions 424 formed at the other side of the substrate 421. The
convexities 422 function as positive lens elements. To enhance
their functioning as lens elements the convexities 422 are covered
by a correction layer 423 of replication type material. Furthermore
the depressions 424 are filled with a layer 425 of replication
material formed as a negative lens. In this way both positive and
negative lenses may be integrated in a single substrate. FIG. 10c
also shows an individual optical module 427 that is obtained by
separating the optical assembly 420 along the lines 424.
[0076] FIG. 10d shows an optical assembly 430 comprising a first
pre-shaped substrate 431 having a plurality of first convexities
432 formed at one side of a first substrate 431 and a plurality of
depressions 434 formed at the other side of the first substrate
431. The first convexities 432 function as positive lens elements.
To enhance their functioning as lens elements the first convexities
432 are covered by a first correction layer 433 of replication type
material. Furthermore the depressions 434 are filled with a second
layer 435 of replication material formed as a negative lens. The
optical assembly 430 further comprises a second pre-shaped
substrate 436, joined with the first pre-formed substrate 431,
having a plurality of second convexities 437 formed at a side
opposing the depressions 434 of the first substrate 431 and
corresponding to the depressions 434. The second convexities 437
function as positive lens elements. To enhance their functioning as
lens elements the second convexities 437 are covered with a third
correction layer 438 of replication material. An advantage of the
shown first pre-shaped substrate 431 is that it integrates the
functionality of a lens substrate and the functionality of a spacer
layer. FIG. 10d also shows an individual optical module 440 that is
obtained by separating the optical assembly 430 along the lines
439.
[0077] The embodiments of the present invention described herein
are intended to be taken in an illustrative and not a limiting
sense. Various modifications may be made to these embodiments by
those skilled in the art without departing from the scope of the
present invention as defined in the appended claims.
[0078] For instance wafer diameters and other dimensions mentioned
in the discussion of the embodiments may be changed. The same holds
for the type of image capturing elements applied.
[0079] Furthermore, although above mostly dicing or sawing is
mentioned as a suitable technique to separate wafer scale packages
or optical assemblies according to the invention, other known
techniques may be applied, for instance, scribing, laser cutting,
etching, or breaking.
* * * * *