U.S. patent application number 13/390191 was filed with the patent office on 2012-05-31 for wafer level lens, production method of wafer level lens, and imaging unit.
This patent application is currently assigned to FUJIFILM CORPORATION. Invention is credited to Yoichi Maruyama.
Application Number | 20120134028 13/390191 |
Document ID | / |
Family ID | 46052342 |
Filed Date | 2012-05-31 |
United States Patent
Application |
20120134028 |
Kind Code |
A1 |
Maruyama; Yoichi |
May 31, 2012 |
WAFER LEVEL LENS, PRODUCTION METHOD OF WAFER LEVEL LENS, AND
IMAGING UNIT
Abstract
A sufficient light-shielding property is obtained by a wafer
level lens having at least one lens module having a substrate and a
plurality of lenses formed on the substrate in which the wafer
level lens has a black resist layer formed on the surface of the
lens module or on the surface of the substrate and the black resist
layer is formed with a pattern having an opening at a part
intersecting the optical axis of the lens, and generation of
defects such as ghosts, flares and the like due to a reflected
light can be prevented and an increase in the production cost can
be suppressed.
Inventors: |
Maruyama; Yoichi; (Tokyo,
JP) |
Assignee: |
FUJIFILM CORPORATION
Tokyo
JP
|
Family ID: |
46052342 |
Appl. No.: |
13/390191 |
Filed: |
August 12, 2010 |
PCT Filed: |
August 12, 2010 |
PCT NO: |
PCT/JP2010/063686 |
371 Date: |
February 13, 2012 |
Current U.S.
Class: |
359/601 ;
427/162 |
Current CPC
Class: |
H01L 27/14627 20130101;
B29D 11/00307 20130101; G02B 7/022 20130101; G02B 3/0031 20130101;
G02B 13/001 20130101; G02B 13/0085 20130101; G02B 1/11 20130101;
B29D 11/00009 20130101 |
Class at
Publication: |
359/601 ;
427/162 |
International
Class: |
G02B 7/02 20060101
G02B007/02; B05D 5/06 20060101 B05D005/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 13, 2009 |
JP |
2009-187858 |
Sep 9, 2009 |
JP |
2009-208365 |
Sep 9, 2009 |
JP |
2009-208366 |
Sep 9, 2009 |
JP |
2009-208367 |
Aug 11, 2010 |
JP |
2010-180625 |
Aug 11, 2010 |
JP |
2010-180626 |
Aug 11, 2010 |
JP |
2010-180627 |
Aug 11, 2010 |
JP |
2010-180628 |
Claims
1. A wafer level lens having at least one lens module having a
substrate and a plurality of lenses formed on said substrate,
wherein the wafer level lens has a black resist layer formed on the
surface of said lens module or on the surface of said substrate,
and said black resist layer is formed with a pattern having an
opening at a part intersecting the optical axis of said lens.
2. A wafer level lens having at least one lens module having a
substrate and a plurality of lenses formed on said substrate,
wherein the wafer level lens has a light shielding layer formed on
an at least partial region of the light incidence side outermost
surface of said lens module and a low reflective light shielding
layer formed with a pattern having an opening at a part
intersecting the optical axis of said lens, on the surface of said
lens module or on the surface of said substrate other than said
light incidence side outermost surface, and said light shielding
layer has lower transmittance for a visible light and higher
reflection rate than said low reflective light shielding layer.
3. The wafer level lens according to claim 2, wherein said low
reflective light shielding layer is a black resist layer.
4. The wafer level lens according to claim 1, wherein said black
resist layer is formed using a black resist composition.
5. The wafer level lens according to claim 1, wherein said black
resist layer contains any one of carbon black, silver-tin and
titanium black.
6. The wafer level lens according to claim 1, wherein said black
resist layer has a reflection rate of 2% or less and a
transmittance of 1% or less for visible light having a wavelength
of 400 to 700 nm.
7. The wafer level lens according to claim 2, wherein said light
shielding layer contains a metal material.
8. The wafer level lens according to claim 2, wherein said light
shielding layer contains chromium.
9. The wafer level lens according to claim 2, wherein said light
shielding layer has a reflection rate of 4% or less and a
transmittance of 0.1% or less for visible light having a wavelength
of 400 to 700 nm.
10. The wafer level lens according to claim 1, wherein a plurality
of said lens modules are laminated via a spacer formed on said
substrate.
11. An imaging unit having lens modules obtained by separating said
substrate of said lens module according to claim 1 so that each
module contains said lens, an imaging device, and a sensor
substrate on which said imaging device is disposed.
12. A method of producing a wafer level lens having at least one
lens module having a substrate and a plurality of lenses formed on
said substrate, wherein before formation of said lenses on said
substrate, a black resist layer is coated on the surface of the
substrate, said coated black resist layer is formed with a pattern
having an opening at a part intersecting the optical axis of said
lens, then, said lens is integrally molded on said substrate.
13. A method of producing a wafer level lens having at least one
lens module having a substrate and a plurality of lenses formed on
said substrate, wherein said lens is molded on said substrate, a
black resist layer is coated on the lens surface of said lens and
on the surface of said substrate, and said black resist layer is
formed with a pattern having an opening at a part intersecting the
optical axis of said lens.
14. The production method of a wafer level lens according to claim
13, wherein said black resist layer is coated by a spray coating
method.
15. The production method of a wafer level lens according to claim
12, wherein said black resist layer is patterned by
photolithography.
16. The production method of a wafer level lens according to claim
12, wherein said lens is molded on said substrate with a mold.
17. The production method of a wafer level lens according to claim
12, wherein said black resist layer is formed using a black resist
composition.
18. The production method of a wafer level lens according to claim
12, wherein said black resist layer contains any one of carbon
black, silver-tin and titanium black.
19. The production method of a wafer level lens according to claim
12, wherein said black resist layer has a reflection rate of 2% or
less and a transmittance of 1% or less for visible light having a
wavelength of 400 to 700 nm.
20. The production method of a wafer level lens according to claim
12, wherein a plurality of said lens modules are laminated via a
spacer formed on said substrate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a wafer level lens, a
production method of a wafer level lens, and an imaging unit.
BACKGROUND ART
[0002] Presently, a portable terminal of electronic instruments
such as cellular phones, PDAs (Personal Digital Assistants) and the
like is loaded with a small and thin imaging unit. Such an imaging
unit is generally equipped with a solid state imaging device such
as a CCD (Charge Coupled Device) image sensor, a CMOS
(Complementary Metal-Oxide Semiconductor) image sensor and the
like, and a lens for forming a subject image on the solid state
imaging device.
[0003] With reduction in size and thickness of a portable terminal,
reduction in size and thickness of an imaging unit is requested.
For lowering the cost of a portable terminal, an efficient
production process is desired. As the method of producing a lot of
such small lenses, there is known a method in which a wafer level
lens having a constitution containing a plurality of lenses molded
on a substrate is produced, and the substrate is cut to separate
the plurality of lenses, to produce a lot of lens modules.
[0004] There is also known a method in which a substrate carrying a
plurality of lenses formed thereon and sensor substrate carrying a
plurality of solid state imaging devices formed thereof are
integrally combined, and the substrate and the sensor substrate are
together cut so as to include the lens and the solid stage imaging
device as a set, to produce a lot of imaging units.
[0005] In the past, examples of the wafer level lens include those
shown in the following patent documents.
[0006] A patent document 1 (JP-A-2005-539276) describes the
constitution of a multi-layered wafer level lens obtained by
laminating substrates carrying a plurality of lenses formed
thereon.
[0007] A patent document 2 (WO-07/107,025) describes a method of
feeding a molding material on a substrate, and molding a lens on
the substrate using a mold.
SUMMARY OF INVENTION
[0008] In the wafer level lens, both a substrate and a lens are
constituted of transparent materials allowing transmission of
light, and light can penetrate any part thereof. Owing to this
constitution, if a wafer level lens is diced and placed on an
imaging device to give an imaging unit and when light transmission
and reflection occur at a region other than the lens surface of the
lens, there is a fear of tendency of defects in optical
performances such as ghosts and flares in taking an image. For
preventing such defects, there is for example envisaged a procedure
of separately attaching a light shielding member to a region other
than the lens of the wafer level lens.
[0009] Originally, the wafer level lens has a big profit of
suppressing production cost since a plurality of lenses are
simultaneously molded on a substrate, and the substrate is diced
and connected to a semiconductor substrate carrying thereon an
imaging device, and the like. However, if a light shielding member
is separately attached, an increase in the production cost
corresponding to this process is inevitable.
[0010] The present invention provides a wafer level lens with which
a sufficient light shielding property is obtained, generation of
defects such as ghosts, flares and the like due to a reflected
light can be prevented, and an increase in the production cost can
be suppressed; a production method of a wafer level lens, and an
imaging unit.
[0011] The present invention provides a wafer level lens having at
least one lens module having a substrate and a plurality of lenses
formed on said substrate, in which the wafer level lens has a black
resist layer formed on the surface of said lens module or on the
surface of said substrate, and said black resist layer is formed
with a pattern having an opening at a part intersecting the optical
axis of said lens.
[0012] In this wafer level lens, light transmission at a region
other than the lens surface of the lens can be prevented by the
black resist layer patterned on at least one of the surface of the
lens module and the surface of the substrate. Because of this
constitution, generation of defects such as ghosts and flares in
taking an image can be prevented, when applied to an imaging module
equipped with an imaging device.
[0013] Since the black resist layer is patterned on the surface of
the lens module or the substrate, there is no necessity to attach
another light shielding member and the like to the wafer level lens
and an increase in the production cost can be suppressed.
[0014] The present invention provides a method of producing a wafer
level lens having at least one lens module having a substrate and a
plurality of lenses formed on said substrate, in which before
formation of said lenses on said substrate, a black resist layer is
coated on the surface of the substrate, said coated black resist
layer is formed with a pattern having an opening at a part
intersecting the optical axis of said lens, then, said lens is
integrally molded on said substrate.
[0015] In this wafer level lens, the black resist layer having a
light shielding function is first patterned on the surface of the
substrate. In this case, the black resist layer can be formed with
a pattern having an opening at a part intersecting the optical axis
of the lens, then, a lens can be molded at a region including the
opening of the black resist layer. Thus, the black resist layer
becomes substantially a lens optical diaphragm.
[0016] According to this method, since also the black resist layer
can be fabricated together with the lens module in the procedure of
producing the wafer level lens, there is no necessity of carrying
out a procedure of attaching another light shielding member and the
like to the wafer level lens and an increase in the production cost
can be suppressed.
[0017] The wafer level lens obtained by this method is capable of
shielding light penetrating a part other than the lens since the
black resist layer has a light shielding function. Accordingly,
generation of defects such as ghosts and flares in taking an image
can be prevented, when applied to an imaging module equipped with
an imaging device.
[0018] The present invention provides a method of producing a wafer
level lens having at least one lens module having a substrate and a
plurality of lenses formed on said substrate, in which said lens is
molded on said substrate, a black resist layer is coated on the
lens surface of said lens and on the surface of said substrate, and
said black resist layer is formed with a pattern having an opening
at a part intersecting the optical axis of said lens.
[0019] According to the procedure of this production method of a
wafer level lens, the lens is first molded on the surface of the
substrate, then, the black resist layer is patterned on a region
excluding the lens surface of the molded lens. Thus, since the
black resist layer can be fabricated together in a process of
producing the wafer level lens, there is no necessity of carrying
out a process of attaching another light shielding member and the
like to the produced wafer level lens and an increase in the
production cost can be suppressed.
[0020] The wafer level lens obtained by this method is capable of
shielding light penetrating a part other than the lens by the black
resist layer. Accordingly, generation of defects such as ghosts and
flares in taking an image can be prevented, when applied to an
imaging module equipped with an imaging device.
[0021] The present invention provides a wafer level lens having at
least one lens module having a substrate and a plurality of lenses
formed on said substrate, in which the wafer level lens has a light
shielding layer formed on an at least partial region of the light
incidence side outermost surface of said lens module and a low
reflective light shielding layer formed with a pattern having an
opening at a part intersecting the optical axis of said lens, on
the surface of said lens module or on the surface of said substrate
other than said light incidence side outermost surface, and said
light shielding layer has lower transmittance for a visible light
and higher reflection rate than said low reflective light shielding
layer.
[0022] In a usual glass wafer, owing to reflection at the surface
and reflection of a transmitted light in the glass wafer,
reflection of 5 to 10% occurs corresponding to about 2 times of the
surface reflection. In contrast, this wafer level lens has a light
shielding layer and a low reflective light shielding layer. The
light shielding layer has a function of preventing transmission of
a light in a substrate, by reflecting a light incoming from the
outside of the wafer level lens. When a plurality of substrates are
disposed, a light incoming from the top substrate surface is
reflected by the light shielding layer at a region other than the
lens, and it is possible to prevent the light penetrated through a
region other than the lens from penetrating between the substrates
and to the sensor substrate side.
[0023] By providing the low reflective light shielding layer,
transmission of a light at a region other than the lens surface of
the lens can be prevented.
[0024] By providing both the light shielding layer and the low
reflective light shielding layer, a light penetrating a part other
than the lens can be reflected by the light shielding layer, and
even if a light penetrates into the substrate without reflection by
the light shielding layer, the light can be shielded by the low
reflective light shielding layer. Accordingly, generation of light
transmission and reflection at a region other than the lens surface
of the lens can be prevented, and defects in optical performances
such as ghosts and flares in taking an image can be suppressed.
[0025] Further, since the light shielding layer and the low
reflective light shielding layer are patterned on the surface of
the substrate, there is no necessity to attach another light
shielding member and the like to the wafer level lens and an
increase in the production cost can be suppressed.
[0026] The present invention is capable of providing a wafer level
lens with which a sufficient light shielding property is obtained,
generation of defects such as ghosts, flares and the like due to a
reflected light can be prevented, and an increase in the production
cost can be suppressed; a production method of a wafer level lens,
and an imaging unit.
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 is a plane view showing one examples of the
constitution of a wafer level lens.
[0028] FIG. 2 is a cross-sectional view taken in a line A-A of the
constitution of the wafer level lens shown in FIG. 1.
[0029] FIG. 3 is a cross-sectional view showing another
constitution example of a wafer level lens.
[0030] FIG. 4 is a cross-sectional view showing one example of the
constitution of an imaging unit.
[0031] FIG. 5 is a view showing the condition of feeding a molding
material to be a lens on a substrate.
[0032] FIG. 6A to FIG. 6C are views showing a procedure of molding
lenses on a substrate with a mold.
[0033] FIG. 7A to FIG. 7C are views explaining a procedure of
patterning a black resist layer on a substrate carrying thereon
molded lenses.
[0034] FIG. 8 is a view showing another constitution example of a
wafer level lens.
[0035] FIG. 9A to FIG. 9C are views showing another procedure of
patterning of a black resist layer.
[0036] FIG. 10A to FIG. 10C are views showing a procedure of
molding lenses on a substrate carrying thereon a patterned black
resist layer.
[0037] FIG. 11A and FIG. 11B are graphs showing the transmittance
and the reflection rate against the wavelength of an incident light
at a black resist layer.
[0038] FIG. 12 is a cross-sectional view showing another
constitution example of a wafer level lens.
[0039] FIG. 13 is a cross-sectional view showing a deformed example
of the wafer level lens shown in FIG. 12.
[0040] FIG. 14 is a cross-sectional view showing an imaging unit
having the lens modules of FIG. 12.
DESCRIPTION OF EMBODIMENTS
[0041] First, the constitutions of a wafer level lens and an
imaging unit will be explained.
[0042] FIG. 1 is a plane view showing one example of the
constitution of a wafer level lens. FIG. 2 is a cross-sectional
view taken in a line A-A of the constitution of the wafer level
lens shown in FIG. 1.
[0043] The wafer level lens has a lens module having a substrate 1
and a plurality of lenses 10 formed on the substrate 1. The
plurality of lenses 10 are arranged on the substrate 1 in
one-dimensional mode or two-dimensional mode. In this constitution
example, an example of a constitution in which the plurality of
lenses 10 are arranged on the substrate 1 in two-dimensional mode
as in FIG. 1 will be explained. The lens 10 is constituted of the
same material as for the substrate 1, and molded on the substrate
1.
[0044] As shown in FIG. 2, the lens 10 has a concave-shaped lens
surface 10a and a lens marginal part 10b around the lens surface
10a. Here, the lens surface 10a has an optical property of allowing
a light incoming into the lens 10 to concentrate or radiate to a
desired direction, and the curvature factor and the surface shape
are designed in view of this optical property. In this constitution
example, the height of the lens marginal part 10b from the
substrate 1 is higher than the center of the lens surface 10a. The
shape of the lens 10 is not particularly restricted, and for
example, a lens having a lens surface 10a protruding in a convex
shape, that is, a convex-shaped lens may be used, or an aspherical
lens may also be used.
[0045] In this example, a plurality of lenses 10 are disposed on
one surface of the substrate 1, however, a constitution having a
plurality of lenses 10 disposed on both surfaces of the substrate 1
may also be used. When a plurality of lenses 10 are disposed on
both surfaces of the substrate 1, molding is so performed that the
optical axis of each lens on one surface corresponds to the optical
axis of each lens on another surface.
[0046] In FIG. 2, the wafer level lens has one lens module having a
plurality of lenses 10 molded on the substrate 1, however, a
constitution having two or more lens modules laminated may also be
used.
[0047] In this wafer level lens, a black resist layer 14 is
provided so as to cover the surface of the lens marginal part 10b
of the lens 10 and the surface of the substrate 1 between the
lenses 10. The black resist layer 14 is patterned on a region
excluding the lens surface 10a of the lens, on the surface of the
lens module. When the wafer level lens has a constitution of
lamination of two or more lens modules, the black resist layer 14
is provided on the surface of at least one lens module. The black
resist layer 14 is formed with a pattern having an opening at a
part intersecting the optical axis of the lens 10. The black resist
layer 14 may partially cover a peripheral part of the lens surface
10a.
[0048] Since the black resist layer 14 shows a lower light
reflection rate as compared with a metal layer and the like,
disadvantages such as ghosts, flares and the like due to light
reflection can be reduced. The black resist layer is formed using a
black resist composition. The black resist composition will be
described later.
[0049] FIG. 3 is a cross-sectional view showing another
constitution example of a wafer level lens.
[0050] In this example, a lens 10 having the same shape as in FIG.
1 is formed on one surface of a substrate 1, and a convex-shaped
lens 20 is molded on another surface. On the another surface, a
spacer is formed for keeping a distance when laminating lens
modules. The spacer 12 is a grid-shaped member in a planar view,
and connected to the another surface of the substrate 1. In this
example, the spacer is connected to the substrate 1 of the lens
module, then, dicing is performed so as to separate one lens 10 and
one lens 20 on the substrate 1. The spacer 12 may also be
integrally molded to the substrate 1 as a part of the substrate
1.
[0051] FIG. 4 is a cross-sectional view showing one example of the
constitution of an imaging unit.
[0052] The imaging unit has lens modules separated for each lens by
dicing of wafer level lenses, an imaging device (here, solid state
imaging device) D, and a sensor substrate W on which the solid
state imaging device D is disposed. The imaging unit of this
example has a constitution in which three lens modules LM1, LM2 and
LM3 are laminated in this order from the light incident side (from
the upper side of FIG. 4).
[0053] In the lens module LM1, a convex-shaped lens 10A is molded
on the upper surface of the substrate 1A, and a lens 20A having a
concave-shaped lens surface is molded on the lower surface. On the
upper surface of the substrate 1A, a black resist layer 14 is
patterned on a region excluding the lens surface of the lens 10A.
On the lens 20A, a black resist layer 14 is patterned on a region
excluding the lens surface. The shape of patterning of the black
resist layer 14 is not particularly restricted, and the black
resist layer 14 may advantageously be formed with a pattern having
an opening at a part intersecting the optical axis of the lenses
10A and 20A, and the same shall apply to the black resist layer 14
of the lens modules LM2 and 3.
[0054] In the lens module LM2, a concave-shaped lens 10B is molded
on the upper surface of the substrate 1B, and a lens 20B having a
convex-shaped lens surface is molded on the lower surface. This
lens module LM2 has basically the same constitution as shown in
FIG. 3. A patterned black resist layer 14 is disposed on a region
excluding the lens surface of the lens 10B on the light incident
side surface of the lens module LM2, that is, on the lens marginal
part and a region of no lens 10B on the surface of the substrate
1B. In this example, the black resist layer 14 is not disposed on
the opposite side surface of the lens module LM2, however, a
patterned black resist layer 14 may be disposed on a region
excluding the lens surface of the lens 20B.
[0055] In the lens module LM3, an aspherical-shaped lens 10C is
molded on the upper surface of the substrate 1C, and a lens 20C
having an aspherical-shaped lens surface is molded on the lower
surface. On both surfaces of the lens module LM3, a patterned black
resist layer 14 is disposed on a region excluding the lens surfaces
of the lens 10C and the lens 20C.
[0056] The lenses 10A, 10B, 10C, 20A, 20B and 20C are disposed in
the form of rotation symmetry against the optical axis. The lens
modules LM1, LM2 and LM3 are connected via spacers 12 so that the
optical axes of all the lenses 10A, 10B, 10C, 20A, 20B and 20C
coincide.
[0057] The lens modules LM1, LM2 and LM3 are mutually connected via
the spacers 12, and the lens module LM3 is connected to the sensor
substrate W via the spacer 12. The lenses 10A, 10B, 10C, 20A, 20B
and 20C of the lens modules LM1, LM2 and LM3 form a subject image
on the solid state imaging device D disposed on the sensor
substrate W.
[0058] The sensor substrate W is molded by cutting a wafer formed
of a semiconductor material such as for example silicon and the
like into an approximately rectangular shape in a planar view. The
solid state imaging device D is disposed on an approximately center
part of the sensor substrate W. The solid state imaging device D
is, for example, a CCD image sensor or a CMOS image sensor. The
solid state imaging device D can be obtained by making a chip,
then, bonding the chip on a semiconductor substrate carrying
thereon formed wiring and the like. Alternatively, known film
formation, photolithography, etching and impurity adding processes
and the like may be performed on the sensor substrate W, thereby
forming an electrode, an insulation film, wiring and the like on
the sensor substrate W, to constitute the solid state imaging
device D.
[0059] The spacer 12 of the lens module LM3 and the sensor
substrate W are connected, for example, using an adhesive and the
like. The spacers 12 are designed so that the lenses 10A, 10B, 10C,
20A, 20B and 20C of the lens modules LM1, LM2 and LM3 form a
subject image on the solid state imaging device D. The spacers 12
are formed with a height keeping a prescribed distance (length in
vertical direction to the surface of the substrate) so that the
lenses 10A, 10B, 10C, 20A, 20B and 20C do not mutually come into
contact between overlapped lens modules LM1,LM2 and LM3 or the lens
module LM3 and the sensor substrate W do not mutually come into
contact.
[0060] The shape of the spacer 12 is not particularly restricted
and can be appropriately changed in a range wherein the lens
modules LM1, LM2 and LM3 can be kept or the lens module LM3 and the
sensor substrate W can be kept in positional relation with a
prescribed distance between them. For example, the spacer 12 may be
a columnar member disposed at four corners of the substrates 1A, 1B
and 1C. The spacer 12 may be a frame-shaped member surrounding the
periphery of the solid state imaging device D. By surrounding the
solid state imaging device D by the frame-shaped spacer 12 to
attain insulation from the outside, light shielding can be
performed so that lights other than a light penetrating the lens do
not come into the solid state imaging device D. Further, by sealing
the solid state imaging device D from the outside, adhesion of
dusts to the solid state imaging device D can be prevented.
[0061] In the case of a constitution of lamination of the lens
modules LM1, LM2 and LM3 as shown in FIG. 4, a reflection layer may
be provided instead of the black resist layer 14, on the surface of
the top lens module LM1 nearest to the light incident side or on
the surface of the substrate 1A. It is preferable that the
reflection layer has a reflection rate of 4% or less and a
transmittance of 0.1% or less for a visible light (wavelength:
400-700 nm). As the reflection material, metals such as chromium
(Cr), gold, tungsten, aluminum, copper, nickel, zinc, silver and
the like or metal materials thereof are preferably used.
[0062] The imaging unit as constituted above is reflow-mounted on a
not-shown circuit substrate embedded in a portable terminal and the
like. On the circuit substrate, a paste-like solder is
appropriately printed previously at a position of mounting of an
imaging unit, and the imaging unit is placed on this, and the
circuit substrate containing this imaging unit is subjected to a
heating treatment such as infrared irradiation and hot air blowing,
thereby welding the imaging unit to the circuit substrate.
[0063] Next, the black resist composition contained in the black
resist layer 14 will be explained.
[0064] [Black Resist Composition]
[0065] The black resist composition of the present invention
contains a black material.
[0066] As the black material, known coloring agents, metal
particles or particles containing a metal can be used. As the
coloring agent, black pigments and dyes can be used. Further,
coloring agents of various hues may be mixed to prepare a black
resist composition having desired transmittance. As these coloring
agents, used can be made of known coloring agents described in JP-A
No. 2006-208796, paragraph numbers [0037] to [0046] and the like,
and combinations thereof. Of them, carbon black, titanium carbon,
iron oxide, titanium oxide, graphite, silver-tin, silver colloid
and the like are preferable from the standpoint of a high light
shielding property, and especially, carbon black, silver-tin and
titanium black are particularly preferable from the standpoint of a
light shielding property. These black materials are dispersed, and
combined with other curing components and the like to give a
composition to be used.
[0067] As the example of carbon black, Pigment Black 7 (carbon
black C. I. No. 77266) is preferable. As commercial products,
Mitsubishi Carbon Black MA100 (manufactured by Mitsubishi Chemical
Corporation) and Mitsubishi Carbon Black #5 (manufactured by
Mitsubishi Chemical Corporation) are mentioned.
[0068] As the example of titanium black, TiO, TiN and a mixture
containing them are preferable. As commercial products, (trade
name) 12S and 13M manufactured by Mitsubishi Materials Corporation
are mentioned. The average primary particle size of titanium black
is preferably 5 to 100 nm, further preferably 10 to 100 nm,
particularly preferably 10 to 50 nm. Though the specific surface
area of titanium black is not particularly restricted, it is
preferable that the value measured by a BET method is usually about
5 to 150 m.sup.2/g, particularly about 20 to 100 m.sup.2/g so that
the water repellency after surface-treatment of such titanium black
with a water repellent agent shows a given performance.
[0069] As the example of graphite, those having an average primary
particle size of 3 .mu.m or less in terms of stokes diameter are
preferable. When the average primary particle size is in the
above-described range, the outline form of a light shielding
pattern become uniform, and sharpness becomes excellent. It is
desirable that 90% or more of particles have an average primary
particle size of 0.1 .mu.m or less. Specifically, particles
obtained by screening of the average primary particle size by
segmentation operations such as centrifugal separation and the like
can be used.
[0070] Further, it is preferable to use metal particles or
particles containing a metal as the black agent from the standpoint
of a high light shielding property. The metal particles or
particles containing a metal are not particularly restricted, and
any compounds may be used. As the metal particles or particles
containing a metal, two or more metals may be used in combination,
and alloys thereof can also be used. Further, composite particles
composed of a metal and a metal compound may also be used.
[0071] The metal particles include suitably particles and alloys
described in JP-A No. 2006-251237, paragraph numbers [0037] to
[0054]. Specifically, shape anisotropic metal fine particles are
mentioned. The shape anisotropic metal fine particles are not
particularly restricted providing they have a shape other than a
spherical form having shape anisotropy, and preferable are metal
fine particles having an infinite form such as a pellet form, a
potato form and the like, a stick form (needle form, cylindrical
form, prismatic form such as rectangular parallelopiped and the
like, rugby ball form and the like), a flat plate form (scale form,
elliptical plate form, plate form), a fiber form, a crenated form,
a coil form and the like. Though the particle shape is not
particularly restricted, a stick forms, an infinite forms and a
plate form are more preferable.
[0072] As the metal particles or particles containing a metal,
those formed from a metal or from a metal and a metal compound are
preferable, and those formed from a metal are particularly
preferable.
[0073] Particularly, it is preferable to contain as the main
component a metal selected from the group consisting of metals of
the long form periodic table (IUPAC1991), 4-th period, 5-th period
and 6-th period. It is preferable to contain a metal selected from
the group consisting of metals of groups II to XIV, and it is more
preferable to contain as the main component a metal selected from
the group consisting of metals of the group II, group VIII, group
IX, group X, group XI, group XII, group XIII and group XIV. Of
them, particles of metals belonging to the 4-th period, 5-th period
or 6-period and belonging to the group II, group X, group XI, group
XII or group IV are further preferable as the metal particle.
[0074] Preferable examples of the metal particles include at least
one selected from copper, silver, gold, platinum, palladium,
nickel, tin, cobalt, rhodium, iridium, iron, calcium, ruthenium,
osmium, manganese, molybdenum, tungsten, niobium, tantalum,
titanium, bismuth, antimony, lead and alloys thereof. Further
preferable metals include copper, silver, gold, platinum,
palladium, nickel, tin, cobalt, rhodium, calcium, iridium and
alloys thereof, more preferable metals include at least one
selected from copper, silver, gold, platinum, palladium, tin,
calcium and alloys thereof, and particularly preferable metals
include at least one selected from copper, silver, gold, platinum,
tin and alloys thereof. Especially, silver is preferable (as the
silver, colloidal silver is preferable), and particles having a
silver-tin alloy are most preferable.
[0075] Examples of silver-tin include fine particles containing as
the main component a silver-tin alloy and having an average
particle size of 1 nm or more and 300 nm or less as described in
JP-A No. 2006-227268, Japanese Patent No. 4237148 and Japanese
Patent No. 4223487.
[0076] [Metal Compound Particle]
[0077] The metal compound is a compound composed of the
above-described metal and other element other than metals. As the
compound composed of the metal and other element, oxides, sulfides,
nitrides, sulfates, carbonates and the like of metals are
mentioned, and as the metal compound particle, particles of these
compounds are suitable. Of them, particles of nitrides and sulfides
are preferable from the standpoint of color tone and easiness of
formation of fine particles.
[0078] Examples of the metal compound include copper(II) oxide,
iron sulfide, silver sulfide, copper(II) sulfide, titanium black
and the like, and silver sulfide is particularly preferable from
the standpoint of color tone, easiness of formation of fine
particles and stability.
[0079] [Composite Particle]
[0080] The composite particle means one particle obtained by
binding of a metal and a metal compound. Examples thereof include
those having different compositions of the inside and the surface
of a particle, those obtained by combining two particles, and the
like. Each of the metal compound and the metal may be used singly
or in combination.
[0081] Specific examples of the composite particle composed of a
metal compound and a metal include a composite particle composed of
silver and silver sulfide, a composite particle composed of silver
and copper(II) oxide, and the like.
[0082] In the case of use of a pigment as the coloring agent to be
used in the present invention, those previously miniaturized into
fine particles are preferably used. As miniaturization of pigment
primary particles, a method of mechanically kneading i) a pigment,
ii) a water-soluble inorganic salt and iii) a water-soluble organic
solvent not substantially dissolving the inorganic salt by a
kneader and the like, a so-called salt milling method and the like
are well known.
[0083] [Solvent]
[0084] In the case of use of a pigment as the coloring agent of the
present invention, it is preferable to first produce a pigment
dispersion liquid prepared by dispersing a pigment in at least one
solvent. The solvent is selected from organic solvents shown below,
and selected in view of the solubility of components contained in
the pigment dispersion liquid, coatability when applied to a resist
composition, and the like, and there is no restriction providing
that these desired physical properties are satisfied, and it is
preferable to select the solvent in view of safety.
[0085] As the solvent which can be suitably used for preparation of
the pigment dispersion liquid, more preferable are methyl
3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl cellosolve
acetate, ethyl lactate, diethylene glycol dimethyl ether, butyl
acetate, methyl 3-methoxypropionate, 2-heptanone, cyclohexanone,
diethylene glycol monoethyl ether acetate, diethylene glycol
monobutyl ether acetate, propylene glycol methyl ether, propylene
glycol monomethyl ether acetate (PGMEA) and the like.
[0086] The content of the solvent in the pigment dispersion liquid
of the present invention is preferably 50 wt % to 95 wt %, more
preferably 50 wt % to 90 wt %. Further, it is particularly
preferably 60 to 90 wt %, most preferably 70 wt % to 90 wt %. When
the content of the solvent is in the above-described range,
dispersion stability is advantageous.
[0087] [Other Components]
[0088] The pigment dispersion liquid may contain other components
in a range not deteriorating the effect of the present invention,
according to the object such as application of the pigment
dispersion liquid and the like.
[0089] It is preferable that the pigment dispersion liquid contains
further a pigment derivative. Particularly, by inclusion of a
pigment derivative having an acidic group, dispersibility and
dispersion stability are improved dramatically.
[0090] As the acidic group carried on the pigment derivative, a
sulfonic group, a carboxylic group and quaternary ammonium salts
thereof are preferable. As a basic group carried on the pigment
derivative, an amino group is preferable.
[0091] Though the use amount of the pigment derivative is not
particularly restricted, it is preferably 5 to 50 wt %, further
preferably 10 to 30 wt % based on the pigment.
[0092] It is also preferable to use a polymer material together for
improving dispersibility. Specific examples of the polymer material
include "Disperbyk-101 (polyamide amine phosphoric acid salt), 107
(carboxylic acid ester), 110 (copolymer containing an acidic
group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170 (polymer
copolymerized compound)", "BYK-P104, P105 (high molecular weight
unsaturated polycarboxylic acid) manufactured by BYK Chemie, "EFKA
4047, 4050, 4010, 4165 (polyurethane type), EFKA 4330, 4340 (block
copolymer), 4400, 4402 (modified polyacrylate), 5010 (polyester
amide), 5765 (high molecular weight polycarboxylic acid salt), 6220
(fatty acid polyester), 6745 (phthalocyanine derivative), 6750 (azo
pigment derivative)" manufactured by EFKA, "Ajisper PB821, PB822"
manufactured by Ajinomoto Fine-Techno Co., Inc., "Florene TG-710
(urethane oligomer)", "Polyflow No. 50E, No. 300 (acrylic
copolymer)" manufactured by Kyoeisha Chemical Co., Ltd., "Disperon
KS-860, 873SN, 874, #2150 (aliphatic poly-valent carboxylic acid),
#7004 (polyether ester), DA-703-50, DA-705, DA-725" manufactured by
Kusumoto Chemicals, Ltd., "Demol RN, N (naphthalenesulfonic acid
formalin polycondensate), MS, C, SN-B (aromatic sulfonic acid
formalin polycondensate)", "Homogenol L-18 (polymer polycarboxylic
acid)", "Emulgen 920, 930, 935, 985 (polyoxyethylene nonyl phenyl
ether)", "Acetamin 86 (stearylamine acetate)" manufactured by Kao
Corporation, "Solsperse 5000 (phthalocyanine derivative), 22000
(azo pigment derivative), 13240 (polyester amine), 3000, 17000,
27000 (polymer having a functional part at the end), 24000, 28000,
32000, 38500 (grafted polymer)" manufactured by The Lubrizol
Corporation and "Nikkol T106 (polyoxyethylene sorbitan monooleate),
MYS-IEX (polyoxyethylene monostearate)" manufactured by Nikko
Chemicals Co., Ltd. (all are trade names), and the like. Also,
amphoteric dispersing agents such as Hinoact T-8000E manufactured
by Kawaken Fine Chemicals Co., Ltd., and the like are mentioned.
Further, polymer compounds described for (F) alkali-soluble resin
described later, and the like are mentioned.
[0093] Particularly, polymer dispersing agents having a polyester
chain in the side chain are preferable from the standpoint of
dispersibility, and resins having an acidic group and a polyester
chain are preferable from the standpoint of dispersibility and the
resolution of a pattern formed by a photolithography method. As the
preferable acidic group in the pigment dispersing agent, acidic
groups having a pKa of 6 or less are preferable, and carboxylic
acids, sulfonic acids and phosphoric acids are particularly
preferable, from the standpoint of an adsorption property.
[0094] The dispersing resins preferably used in the present
invention will be explained below.
[0095] The preferable dispersing resins are graft copolymers having
in the molecule a graft chain selected from a polyester structure,
a polyether structure and a polyacrylate structure and having an
number of atoms excluding a hydrogen atom of in the range of 40 to
10000, and graft copolymers containing a structure unit represented
by any one of the following formulae (1) to (5).
##STR00001##
[in the formula (1) to the formula (5), X.sup.1, X.sup.2, X.sup.3,
X.sup.4, X.sup.5 and X.sup.6 represent each independently a
hydrogen atom or a monovalent organic group, Y.sup.1, Y.sup.2,
Y.sup.3, Y.sup.4 and Y.sup.5 represent each independently a
divalent connecting group, Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4 and
Z.sup.5 represent each independently a hydrogen atom or a
monovalent organic group. R represents a hydrogen atom or a
monovalent organic group, and Rs of different structures may exist
in the copolymer. n, m, p, q and r represent each independently an
integer of 1 to 500.].
[0096] As specific examples, compounds shown below are mentioned.
In the following exemplified compounds, the numerical value
described along with each structural unit (numerical value
described along with the main chain repeating unit) represents the
content [wt %] of the structural unit. The numerical value
described along with the side chain repeating unit represents the
number of repetition of the repeating unit.
##STR00002## ##STR00003## ##STR00004## ##STR00005##
[0097] In the case of use of an inorganic pigment as the black
material, it is preferable to first prepare a pigment dispersed
composition from a pigment, a dispersing agent and a suitable
solvent, then, blend this in a polymerizable composition, from the
standpoint of dispersibility.
[0098] Also in the case of use of an inorganic pigment and an
infrared ray absorbing dye as the black material, dyes other than
materials exemplified as the existing organic pigment having a hue
of red, blue, green, yellow, cyan, magenta, gray and the like may
be appropriately selected and combined, to realize a desired
spectrum.
[0099] The content of the pigment dispersing agent in such a
pigment dispersed composition is preferably 1 wt % to 90 wt %, more
preferably 3 wt % to 70 wt % with respect to the total solid weight
of the coloring agents (including the black pigment and other
coloring agents) in the pigment dispersed composition.
[0100] These polymer materials may be used singly or in combination
of two or more of them. When the polymer materials are used in
combination, the content of the polymer materials is preferably 1
wt % to 100 wt %, more preferably 3 wt % to 80 wt %, further
preferably 5 wt % to 50 wt % with respect to (A) the specified
resin according to the present invention.
[0101] [Photosensitive Component]
[0102] By further adding a photosensitive component to the black
material, a black resist composition is obtained. As the black
resist composition, any of compositions having a positive action
showing an increase in solubility of an exposed part into a
developing solution by a light and compositions having a negative
action showing a decrease in solubility into a developing solution
can be adopted. For example, by adding a photopolymerization
initiator and a compound containing an ethylenically unsaturated
double bond as the photosensitive component, a black resist
composition excellent in resolution, chromatic characteristic,
coatability and developing property can be obtained.
[0103] (Photopolymerization Initiator)
[0104] It is preferable that the black resist composition contains
a photopolymerization initiator for improving sensitivity and
pattern formability. The photopolymerization initiator in the
present invention is a compound which is decomposed by a light to
initiate and promote polymerization of polymerizable components in
the present invention, and those showing absorption in the
wavelength range of 300 nm to 500 nm are preferable. The
photopolymerization initiators can be used singly or in combination
of two or more of them.
[0105] As the photopolymerization initiator, compounds selected
from the group consisting of triazine compounds, alkylamino
compounds, benzyl dimethyl ketal compounds, .alpha.-hydroxyketone
compounds, .alpha.-aminoketone compounds, acylphosphine compounds,
phosphine oxide compounds, metallocene compounds, oxime compounds,
biimidazole compounds, onium compounds, benzothiazole compounds,
benzophenone compounds, acetophenone compounds and derivatives
thereof, cyclopentadiene-benzene-iron complexes and salts thereof,
halomethyloxadiazole compounds and 3-aryl-substituted coumarin
compounds are preferable from the standpoint of exposure
sensitivity.
[0106] The photopolymerization initiator includes more preferably
triazine compounds, alkylamino compounds, .alpha.-aminoketone
compounds, acylphosphine compounds, phosphine oxide compounds,
oxime compounds, biimidazole compounds, onium compounds,
benzophenone compounds and acetophenone compounds, and at least one
compound selected from the group consisting of triazine compounds,
alkylamino compounds, oxime compounds and biimidazole compounds is
further preferable, and most preferable are oxime compounds and
biimidazole compounds.
[0107] Particularly, the pigment concentration of the black resist
composition is high in its formulation for obtaining a sufficient
light shielding property, in contrast, the addition amount of the
initiator becomes small, to lower sensitivity. When initiators
generating a halogen-containing compound in exposure such as
triazine compounds and the like are used in performing exposure by
a stepper, corrosion of an apparatus occurs, thus, such initiators
cannot be used. In view of such reasons, oxime compounds are
preferable, and particularly, oxime compounds showing absorption at
365 nm are most preferable, as the photopolymerization initiator
satisfying sensitivity and various properties.
[0108] The content of the photopolymerization initiator is
preferably 0.1 wt % to 50 wt %, more preferably 0.5 wt % to 30 wt
%, particularly preferably 1 wt % to 20 wt %, with respect to the
total solid content of the black resist composition. In this range,
excellent sensitivity and pattern formability are obtained.
[0109] (Compound Containing Ethylenically Unsaturated Double
Bond)
[0110] The black resist composition of the present invention can
contain a compound containing an ethylenically unsaturated double
bond (hereinafter, referred to simply as "polymerizable compound"
in some cases) other than the above-described resins.
[0111] The compound containing an ethylenically unsaturated double
bond is an addition-polymerizable compound having at least one
ethylenically unsaturated double bond, other than the
above-described resins, and selected from compounds containing at
least one end ethylenically unsaturated bond, preferably containing
two or more end ethylenically unsaturated bonds. Such compounds are
known widely in the art, and these compounds can be used without
limitation in the present invention. These compounds have a
chemical form such as, for example, a monomer, a prepolymer, that
is, a dimer, a trimer and an oligomer, or a mixture thereof, and a
copolymer thereof or the like.
[0112] Examples of the polymerizable compound which can be suitably
used in the present invention include compounds described in JP-A
No. 2008-233244, paragraph numbers [0115] to [0116] and compounds
described in JP-A No. 2009-20453, paragraph numbers [0100] to
[0109], and these compounds can be used according to the
object.
[0113] As the polymerizable compound which can be used in the
present invention, preferable are bisphenol A diacrylate
EO-modified body, pentaerythritol triacrylate, pentaerythritol
tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol
pentaacrylate succinic acid-modified body, dipentaerythritol
hexaacrylate, tri(acryloyloxyethyl) isocyanurate, pentaerythritol
tetraacrylate EO-modified body, dipentaerythritol hexaacrylate
EO-modified body and the like, and as commercial products, DPHA-40H
(manufactured by Nippon Kayaku Co., Ltd.), UA-306H, UA-306T,
UA-3061, AH-600, T-600, AI-600 (manufactured by Kyoei K.K.) are
preferable.
[0114] The content of the compound containing an ethylenically
unsaturated double bond is preferably 1 wt % to 90 wt %, more
preferably 5 wt % to 80 wt %, further preferably 10 wt % to 70 wt %
in the solid content of the black resist composition.
[0115] It is preferable that the black resist composition contains
further an alkali-soluble resin. By inclusion of an alkali-soluble
resin, developability and pattern formability are improved.
[0116] [Alkali-Soluble Resin]
[0117] The alkali-soluble resin is a linear organic high molecular
weight polymer, and can be appropriately selected from
alkali-soluble resins having at least one group promoting alkali
solubility (for example, a carboxyl group, a phosphoric group, a
sulfonic group, a hydroxyl group and the like) in a molecule
(preferably, a molecule containing an acrylic copolymer or a
styrene copolymer as the main chain).
[0118] Examples of the above-described alkali-soluble resin include
resins described in JP-A No. 2008-233244, paragraph numbers [0096]
to [0111].
[0119] As specific constituent units of the alkali-soluble resin,
particularly, copolymers composed of (meth)acrylic acid and other
copolymerizable monomer, that is, acrylic resins are suitable.
[0120] Of them, benzyl (meth)acrylate/(meth)acrylic acid copolymers
and multicomponent copolymers composed of benzyl
(meth)acrylate/(meth)acrylic acid/other monomer are particularly
suitable.
[0121] It is preferable that the acrylic resin has an acid value in
the range of 20 mg KOH/g to 200 mg KOH/g. In this range,
developability and pattern formability are excellent.
[0122] The weight-average molecular weight Mw (polystyrene-reduced
value measured by a GPC method) of the acrylic resin is preferably
2000 to 100000, more preferably 3000 to 50000, for realizing a
viscosity range for easy coating of a color resist and the like and
for ensuring film strength.
[0123] The above-specified range of the acid value of the acrylic
resin can be easily obtained by appropriately adjusting
copolymerization ratios of monomers. The above-described range of
the weight-average molecular weight can be easily obtained by using
a suitable amount of a chain transfer agent according to the
polymerization method in copolymerization of monomers.
[0124] The acrylic resin can be produced, for example, by a radical
polymerization method known per se. Polymerization conditions such
as the temperature and the pressure in producing an acrylic resin
by a radical polymerization method, the kind and the amount of a
radical initiator, the kind of a solvent and the like can be easily
set by those skilled in the art, and condition setting thereof is
possible.
[0125] The addition amount in adding an alkali-soluble resin to the
black resist composition is preferably 5 wt % to 90 wt %, more
preferably 10 wt % to 60 wt % with respect to the total solid
content of the composition. In this range, film strength is high, a
membrane property is excellent, and image formability is
excellent.
[0126] For improving the cross-linkage efficiency of the black
resist composition in the present invention, alkali-soluble resins
having a polymerizable group may be used singly or may be used
together with an alkali-soluble resin having no polymerizable
group, and polymers containing an aryl group, a (meth)acryl group,
an aryloxyalkyl group or the like in the side chain are useful.
[0127] An alkali-soluble resin having a polymerizable double bond
can be developed with an alkali developing liquid, and further have
a photo-curing property and a thermosetting property.
[0128] Examples of these polymers having a polymerizable group
include, but not limited to, the following resins providing an
alkali-soluble group such as a COOH group, an OH group and the like
and a carbon-carbon unsaturated bond are contained.
[0129] (1) Urethane-modified polymerizable double bond-containing
acrylic resins obtained by previously reacting an isocyanate group
with an OH group, and reacting a compound having one unreacted
isocyanate group and containing at least one (meth)acryloyl group
with an acrylic resin containing a carboxyl group.
[0130] (2) Unsaturated group-containing acrylic resins obtained by
reacting an acrylic resin containing a carboxyl group with a
compound having an epoxy group and a polymerizable double bond in
the molecule.
[0131] (3) Acid-pendant epoxy acrylate resins.
[0132] (4) Polymerizable double bond-containing acrylic resins
obtained by reacting an acrylic resin containing an OH group with a
dibasic acid anhydride having a polymerizable double bond.
[0133] Of the above-described examples, the resins (1) and (2) are
preferable.
[0134] The acid value of alkali-soluble resin having a
polymerizable double bond is preferably 30 mg KOH/g to 150 mg
KOH/g, more preferably 35 mg KOH/g to 120 mg KOH/g, and the
weight-average molecular weight Mw is preferably 2000 to 50000,
more preferably 3000 to 30000.
[0135] Examples of commercial products of the alkali-soluble resin
include Dianal NR series (manufactured by Mitsubishi Rayon Co.,
Ltd.); Photomer 6173 (COOH group-containing polyurethane acrylic
oligomer, manufactured by Diamond Shamrock Co., Ltd.); Viscoat
R-264, KS resist 106 (all are manufactured by Osaka Organic
Chemical Industry Ltd.); Cyclomer P series, Placcel CF200 series
(all are manufactured by Daicel Chemical Industries, Ltd.); Ebecryl
3800 (manufactured by Daicel-UCB company Ltd.), and the like.
[0136] [Organic Solvent]
[0137] The black resist composition in the present invention can be
constituted, in general, using an organic solvent. The organic
solvent is basically not particularly restricted providing that the
solubility of components and the coatability of the black resist
composition are satisfied, and it is preferable that the organic
solvent is selected in view of particularly the solubility, the
coatability and the safety of an ultraviolet absorber and a binder.
In preparing the black resist composition in the present invention,
at least two organic solvents are preferably contained.
[0138] The organic solvent suitably includes esters: for example,
ethyl acetate, n-butyl acetate, isobutyl acetate, amyl formate,
isoamyl acetate, isobutyl acetate, butyl propionate, isopropyl
butyrate, ethyl butyrate, butyl butyrate, methyl lactate, ethyl
lactate, alkyl oxyacetates (e.g.: methyl oxyacetate, ethyl
oxyacetate, butyl oxyacetate (for example, methyl methoxyacetate,
ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate,
ethyl ethoxyacetate and the like)), alkyl 3-oxypropionates (e.g.:
methyl 3-oxypropionate, ethyl 3-oxypropionate and the like (for
example, methyl 3-methoxypropionate, ethyl 3-methoxypropionate,
methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate and the like)),
alkyl 2-oxypropionates (e.g.: methyl 2-oxypropionate, ethyl
2-oxypropionate, propyl 2-oxypropionate and the like (for example,
methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl
2-methoxypropionate, methyl 2-ethoxypropionate, ethyl
2-ethoxypropionate)), methyl 2-oxy-2-methylpropionate and ethyl
2-oxy-2-methylpropionate (for example, methyl
2-methoxy-2-methylpropionate, ethyl 2-ethoxy-2-methylpropionate and
the like), methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl
acetoacetate, ethyl acetoacetate, methyl 2-oxobutanoate, ethyl
2-oxobutanoate and the like, ethers: for example, diethylene glycol
dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether,
ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl
cellosolve acetate, diethylene glycol monomethyl ether, diethylene
glycol monoethyl ether, diethylene glycol monobutyl ether,
propylene glycol monomethyl ether, propylene glycol monomethyl
ether acetate, propylene glycol monoethyl ether acetate, propylene
glycol monopropyl ether acetate and the like, ketones: for example,
methyl ethyl ketone, cyclohexanone, 2-heptanone, 3-heptanone and
the like, and aromatic hydrocarbons, for example, toluene, xylene
and the like.
[0139] It is also preferable that two or more of these organic
solvents are mixed, from the standpoint of the solubility of an
ultraviolet absorber and an alkali-soluble resin, improvement in a
coated surface state, and the like. In this case, particularly
preferable are mixed solutions constituted of two or more compounds
selected from methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate,
ethyl cellosolve acetate, ethyl lactate, diethylene glycol dimethyl
ether, butyl acetate, methyl 3-methoxypropionate, 2-heptanone,
cyclohexanone, ethyl carbitol acetate, butyl carbitol acetate,
propylene glycol methyl ether and propylene glycol methyl ether
acetate.
[0140] Regarding the content of the organic solvent in the colored
curing composition, the total solid concentration of the
composition is preferably 5 to 80 wt %, further preferably 5 to 60
wt %, particularly preferably 10 to 50 wt % from the standpoint of
coatability.
[0141] The black resist composition may further contain components
described in detail below if necessary.
[Sensitizer]
[0142] The black resist composition may contain a sensitizer for
the purpose of improving the radical generation efficiency of a
polymerization initiator and elongating the photosensitization
wavelength. As the sensitizer which can be used in the present
invention, those sensitizing the above-described
photopolymerization initiator by an electron transfer mechanism or
an energy transfer mechanism are preferable. The sensitizer which
can be used in the present invention includes those belonging to
compounds listed below and having an absorption wavelength in the
range of 300 nm to 450 nm.
[0143] Preferable examples of the sensitizer include those
belonging to the following compounds and having an absorption
wavelength in the range of 330 nm to 450 nm.
[0144] Examples thereof include polycyclic aromatics (for example,
phenanthrene, anthracene, pyrene, perylene, triphenylene,
9,10-dialkoxyanthracene), xanthenes (for example, fluorescein,
eosin, erythrosine, rhodamine B, rose bengal), thioxanthones
(isopropylthioxanthone, diethylthioxanthone, chlorothioxanthone),
cyanines (for example, thiacarbocyanine, oxacarbocyanine),
merocyanines (for example, merocyanine, carbomerocyanine),
phthalocyanines, thiazines (for example, thionine, methylene blue,
toluidine blue), acridines (for example, acridine orange,
chloroflavin, acriflavine), anthraquinones (for example,
anthraquinone), squaliums (for example, squalium), acridine orange,
coumarins (for example, 7-diethylamino-4-methyl coumarin),
ketocoumarin, phenothiazines, phenazines, styrylbenzenes, azo
compounds, diphenylmethane, tiphenylmethane, distyrylbenzenes,
carbazoles, porphyrin, Spiro compounds, quinacridone, indigo,
styryl, pyrylium compounds, pyrromethene compounds,
pyrazolotriazole compounds, benzothiazole compounds, barbituric
acid derivatives, thiobarbituric acid derivatives, acetophenone,
benzophenone, thioxanthone, Michler's ketone and the like (aromatic
ketone compounds), N-aryloxazolidinone and the like (heterocyclic
compounds), and the like.
[0145] Further, compounds described in EU Patent No. 568,993, U.S.
Pat. Nos. 4,508,811 and 5,227,227, JP-A No. 2001-125255, JP-A No.
11-271969 and the like, etc. are listed.
[0146] [Polymerization Inhibitor]
[0147] It is desirable to add a small amount of a thermal
polymerization preventing agent for inhibiting unnecessary thermal
polymerization of a compound having a polymerizable ethylenically
unsaturated double bond during production or during storage of the
black resist composition.
[0148] The thermal polymerization preventing agent includes
hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol,
t-butylcatechol, benzoquinone,
4,4'-thiobis(3-methyl-6-t-butylphenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol),
N-nitrosophenylhydroxyamine primary cerium salt, and the like.
[0149] The addition amount of the polymerization inhibitor is
preferably about 0.01 wt % to about 5 wt % with respect to the
weight of the whole composition. If necessary, a higher fatty acid
derivative such as behenic acid and behenic amide and the like may
be added to be eccentrically located on the surface of a
photosensitive layer in a process of drying after coating, for
preventing polymerization inhibition by oxygen. The addition amount
of the higher fatty acid derivative is preferably about 0.5 wt % to
about 10 wt % based on the whole composition.
[0150] [Surfactant]
[0151] To the black resist composition, various surfactants may be
added from the standpoint of further improving coatability. As the
surfactant, use can be made of various surfactants such as
fluorine-based surfactants, nonionic surfactants, cationic
surfactants, anionic surfactants, silicone surfactants and the
like.
[0152] Particularly when the black resist composition contains a
fluorine-based surfactant, the liquid property (particularly,
flowability) when a coating liquid is prepared is further improved,
thus, the uniformity of coated thickness and liquid saving can be
further improved.
[0153] That is, in the case of forming a film using a coating
liquid prepared by using a black resist composition containing a
fluorine-based surfactant, the surface tension between a coating
surface and a coating liquid is lowered, thereby enhancing
wettability to the coating surface and improving coatability on the
coating surface. This is effective in that a film having uniform
thickness of small irregularity can be suitably formed even in the
case of formation of a thin film of about several .mu.m with a
small amount of liquid.
[0154] The fluorine content in the fluorine-based surfactant is
suitably 3 wt % to 40 wt %, more preferably 5 wt % to 30 wt %,
particularly preferably 7 wt % to 25 wt %. The fluorine-based
surfactant having a fluorine content in this range is effective in
uniformity of the thickness of a coated film and in liquid saving,
and also shows excellent solubility in the black resist
composition.
[0155] Examples of the fluorine-based surfactant include Megafac
F171, F172, F173, F176, F177, F141, F142, F143, F144, R30, F437,
475, F479, F482, F554, F780 and F781 (all are manufactured by DIC
Corporation), Fluorad FC430, FC431 and FC171 (all are manufactured
by Sumitomo 3M Limited), Surflon S-382, SC-101, SC-103, SC-104,
SC-105, SC1068, SC-381, SC-383, S393 and KH-40 (all are
manufactured by Asahi Glass Co., Ltd.), Solsperse 20000 (The
Lubrizole Corporation), and the like.
[0156] Specific examples of the nonionic surfactant include
glycerol, trimethylolpropane, trimethylolethane and ethoxylates and
propoxylates thereof (for example, glycerol propoxylate, glycerin
ethoxylate and the like), polyoxyethylene lauryl ether,
polyoxyethylene stearyl ether, polyoxyethylene oleyl ether,
polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl
ether, polyethylene glycol dilaurate, polyethylene glycol
distearate, sorbitan fatty esters (Pluronic L10, L31, L61, L62,
10R5, 17R2 and 25R2, Tetronic 304, 701, 704, 901, 904 and 150R1
manufactured by BASF), and the like.
[0157] Specific examples of the cationic surfactant include
phthalocyanine derivatives (trade name: EFKA-745, manufactured by
Morishita & Co., Ltd.), organosiloxane polymer KP341
(manufactured by Shin-Etsu Chemical Co., Ltd.), (meth)acrylic acid
(co)polymer Polyflow No. 75, No. 90 and No. 95 (manufactured by
Kyoeisha Chemical Co., Ltd.), W001 (manufactured by Yusho Co.,
Ltd.) and the like.
[0158] Specific examples of the anionic surfactant include W004,
W005 and W017 (manufactured by Yusho Co., Ltd.), and the like.
[0159] Examples of the silicone surfactant include "Toraysilicone
DC3PA", "Toraysilicone SH7PA", "Toraysilicone DC11PA",
"Toraysilicone SH21PA", "Toraysilicone SH28PA", "Toraysilicone
SH29PA", "Toraysilicone SH30PA" and "Toraysilicone SH8400"
manufactured by Dow Corning Toray Co., Ltd., "TSF-4440",
"TSF-4300", "TSF-4445", "TSF-4460" and "TSF-4452" manufactured by
Momentive Performance Materials Inc., "KP341", "KF6001" and
"KF6002" manufactured by Shin-Etsu Chemical Co., Ltd., "BYK307",
"BYK323" and "BYK330" manufactured by BYK, and the like. The
surfactants may be used singly or in combination of two or more of
them.
[0160] The addition amount of the surfactant is preferably 0.001 wt
% to 20 wt %, more preferably 0.005 wt % to 1.0 wt % with respect
to the total weight of the black resist composition.
[0161] [Other Additives]
[0162] Further, inorganic fillers, plasticizers, and support close
adhesion agents capable of improving close adhesion to a support
may be added for improving the physical properties of a cured
membrane.
[0163] Examples of the plasticizer include dioctyl phthalate,
didodecyl phthalate, triethylene glycol dicaprylate, dimethyl
glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl
sebacate, triacetylglycerin and the like, and in the case of use of
a binder, it can be added in an amount of 10 wt % or less with
respect to the total weight of the binder and a compound having an
ethylenically unsaturated double bond.
[0164] When the black resist composition is applied to the surface
a cured material such as a support and the like, additives for
improving the close adhesion with the surface of the cured material
(hereinafter, referred to as "support close adhesion agent") may be
added.
[0165] As the support close adhesion agent, known materials can be
used, and it is particularly preferable to use silane coupling
agents, titanate coupling agents and aluminum coupling agents.
[0166] As the silane coupling agent, for example,
.gamma.-methacryloxypropyltrimethoxysilane,
.gamma.-methacryloxypropyltriethoxysilane,
.gamma.-acryloxypropyltrimethoxysilane,
.gamma.-acryloxypropyltriethoxysilane,
.gamma.-mercaptopropyltrimethoxysilane, aminopropyltriethoxysilane
and phenyltrimethoxysilane are preferable, and
.gamma.-methacryloxypropyltrimethoxysilane is most preferable.
[0167] The content of the support close adhesion agent is
preferably 0.1 wt % or more and 30 wt % or less, more preferably
0.5 wt % or more and 20 wt % or less, particularly preferably 1 wt
% or more and 10 wt % or less, with respect to the total solid
content of the black resist composition of the present invention,
from the standpoint of no residue of the black resist composition
on an unexposed part.
[0168] In the wafer level lens, the light reflection rate of the
black resist layer 14 is lower as compared with a layer composed of
a metal or the like. Because of this reason, defects such as
ghosts, flares and the like due to a reflected light can be reduced
while sufficiently shielding a light by the black resist layer 14.
For example, the above-described effect can be obtained when the
reflection rate is 2% or less and the transmittance is 1% or less
for a visible light having a wavelength of 400 to 700 nm. The black
resist layer 14 having such a property can be formed by using the
above-described black resist composition.
[0169] The reflection rate in the present invention can be measured
by using a spectrophotometer for the composition coated on a
desired substrate. The reflected light of a visible light (400-700
nm) is measured. Lower reflection lights are preferable, and the
average thereof is 2% or less, preferably, the reflection rate is
1.5% or less.
[0170] Next, preferable examples of the procedure for producing the
above-described wafer level lens will be explained. In embodiments
to be explained below, explanations of members having the same
constitution and action with those of the members already explained
above are simplified or omitted by attaching the same marks or
correspondent marks in a figure.
[0171] FIG. 5 is a view showing the condition of feeding a molding
material to be a lens on a substrate. FIG. 6A to FIG. 6C are views
showing a procedure of molding lenses on a substrate with a
mold.
[0172] As the material for forming the lens 10, for example, glass
can be used. Glass is suitable as a material of a lens needing
large power since there are a lot of glass materials and those
having a high refractive index can be selected. Further, glass is
excellent in heat resistance, and is suitable for reflow mounting
of the above-described imaging unit.
[0173] As the material for forming the lens 10, resins can also be
used. Resins are excellent in processability, and are suitable for
forming a lens surface with a mold simply and at low cost. As the
resin, any one of ultraviolet curable resins, thermosetting resins
and thermoplastic resins can be used, and when reflow mounting of
the above-described image unit is taken into consideration, those
having a relatively high softening point of 200.degree. C. or
higher are preferable, and those of 250.degree. C. or higher are
more preferable.
[0174] As the ultraviolet curable resin, exemplified are
ultraviolet curable silicon resins, ultraviolet curable epoxy
resins, acrylic resins and the like. As the epoxy resin, those
having a linear expansion coefficient of 40 to 80 [10.sup.-6/K] and
a refractive index of 1.50 to 1.70, preferably 1.50 to 1.65 can be
used. As the thermosetting resin, exemplified are thermosetting
silicon resins, thermosetting epoxy resins, thermosetting phenol
resins, thermosetting acrylic resins and the like. For example, as
the silicon resin, those having a linear expansion coefficient of
30 to 160 [10.sup.-6/K] and a refractive index of 1.40 to 1.55 can
be used. The epoxy resins having a linear expansion coefficient of
40 to 80 [10.sup.-6/K] and a refractive index of 1.50 to 1.70,
preferably 1.50 to 1.65 can be used. The phenol resins having a
linear expansion coefficient of 30 to 70 [10.sup.-6/K] and a
refractive index of 1.50 to 1.70 can be used. The acrylic resins
having a linear expansion coefficient of 20 to 60 [10.sup.-6/K] and
a refractive index of 1.40 to 1.60, preferably 1.50 to 1.60 can be
used. As the thermosetting resin, specifically exemplified are
SMX-7852 and SMX-7877 manufactured by Fuji Polymer Industries Co.,
Ltd., IVSM-4500 manufactured by Toshiba Corporation, SR-7010
manufactured by Dow Corning Toray Co., Ltd., and the like. As the
thermoplastic resin, exemplified are polycarbonate resins,
polysulfone resins, polyether sulfone resins and the like. The
polycarboantes having a linear expansion coefficient of 60 to 70
[10.sup.-6/K] and a refractive index of 1.40-1.70, preferably 1.50
to 1.65 can be used. The polysulfone resins having a linear
expansion coefficient of 15 to 60 [10.sup.-6/K] and a refractive
index of 1.63 can be used. The polyether sulfone resins having a
linear expansion coefficient of 20 to 60 [10.sup.-6/K] and a
refractive index of 1.65 can be used.
[0175] In general, optical glass has a linear expansion coefficient
at 20.degree. C. of 4.9 to 14.3[10.sup.-6/K] and a refractive index
of 1.4 to 2.1 at a wavelength of 589.3 nm. Quartz glass has a
linear expansion coefficient of 0.1 to 0.5[10.sup.-6/K] and a
refractive index of about 1.45.
[0176] Further, it is preferable to use an organic inorganic
composite material obtained by dispersing inorganic fine particles
in a resin matrix. Examples of the inorganic fine particles include
oxides fine particles, sulfides fine particles, selenide fine
particles and telluride fine particles. More specifically, fine
particles of, for example, zirconium oxide, titanium oxide, zinc
oxide, tin oxide, zinc sulfide and the like are mentioned.
[0177] The inorganic fine particles may be used singly or in
combination of two or more of them. A composite composed of several
components may also be used. Further, the inorganic fine particles
may be doped with a dissimilar metal, the surface layer thereof may
be covered with a dissimilar metal oxide such as silica, alumina
and the like, or the surface thereof may be modified with a silane
coupling agent, a titanate coupling agent, an organic acid
(carboxylic acids, sulfonic acids, phosphoric acids, phosphonic
acids and the like) or a dispersing agent having an organic acid
group, or the like, for the purpose of reducing photocatalytic
activity, reducing water absorption coefficient, and the like.
[0178] When the number average particle size of the inorganic fine
particles is too small, the properties of the substance may change
in some cases. When a difference in refractive index between the
resin matrix and the inorganic fine particles is large, an
influence by Rayleigh scattering becomes remarkable if the number
average particle size of the inorganic fine particles is too large.
Because of this reason, it is preferably 1 nm to 15 nm, further
preferably 2 nm to 10 nm, particularly preferably 3 nm to 7 nm. It
is desirable that the inorganic fine particles have narrower
particle size distribution. Though the definition methods of such
monodispersed particles are various, for example, the numerical
value prescription range as described in JP-A No. 2006-160992 is a
preferable particle size distribution range. The above-described
number-average primary particle size can be measured, for example,
by an X-ray diffraction (XRD) instrument, a transmission electron
microscope (TEM) and the like.
[0179] The refractive index of the inorganic fine particles is
preferably 1.90 to 3.00, further preferably 1.90 to 2.70,
particularly preferably 2.00 to 2.70 at a temperature of 22.degree.
C. and a wavelength of 589.3 nm.
[0180] The content of the inorganic fine particles in the resin is
preferably 5 wt % or more, further preferably 10 to 70 wt %,
particularly preferably 30 to 60 wt %, from the standpoint of
transparency and enhanced refractive index.
[0181] As the resin used in the organic inorganic composite
material, known ultraviolet curable resins, thermosetting resins
and thermoplastic resins can be used. Further mentioned are resins
having a refractive index of larger than 1.60 described in JP-A No.
2007-93893, block copolymers constituted of a hydrophobic segment
and a hydrophilic segment described in JP-A No. 2007-211164, resins
having a functional group which is capable of forming any chemical
bond to the inorganic fine particles at the polymer end or side
chain described in JP-A No. 2007-238929, Japanese Patent
Application No. 2008-12645, JP-A No. 2010-043191, JP-A No.
2010-065063 and JP-A No. 2010-54817, thermoplastic resins described
in JP-A No. 2010-031186 and JP-A No. 2010-37368, and the like. To
the organic inorganic composite material, additives such as
plasticizers, dispersing agents and the like can be added if
necessary.
[0182] As the material of the substrate 1, the same molding
material as that of the lens 10 can be used. The substrate 1 may
also be fabricated by using a different material from the molding
material of the lens 10 providing that it is a material transparent
to a visible light such as glass and the like. In this case, it is
preferable that that the linear expansion coefficient of the
material forming the substrate 1 is close to the linear expansion
coefficient of the material forming the lens 10. When the linear
expansion coefficient of the material forming the lens 10 is closed
to the linear expansion coefficient of the material forming the
substrate 1, disadvantages such as distortion and cracking of the
lens 10 can be avoided in reflow mounting of the above-described
imaging unit 1.
[0183] An infrared filter (IR filter) may be formed on the surface
of the light incident side of the substrate 1 (not shown).
[0184] As shown in FIG. 5, a molding material M is dropped by using
a dispenser 50 on a part of molding of a lens of the substrate 1.
Here, a molding material M in an amount corresponding to one lens
10 is fed to one feeding part.
[0185] After feeding the molding material M on the substrate 1, a
mold 60 for molding a lens is placed as shown in FIG. 6A. On the
mold 60, concave portions 62 for transferring the shape of the lens
10 are provided corresponding to the number of desired lenses
10.
[0186] As shown in FIG. 6B, the mold 60 is pushed to the molding
material M on the substrate 1, thereby deforming the molding
material M to correspond to the shape of the concave portion. Under
the condition of pushing the mold 60 to molding material M, heat or
ultraviolet ray is irradiated from the outside of the mold to cure
the molding resin M when the molding resin M is a thermosetting
resin or an ultraviolet curable resin.
[0187] After curing of the molding material M, the substrate 1 and
the lenses 10 are released from the mold 60 as shown in FIG.
6C.
[0188] FIG. 7A to FIG. 7C are views explaining a procedure of
patterning the black resist layer on the substrate carrying thereon
molded lenses.
[Pattern Formation Method]
[0189] Next, the pattern formation method will be explained.
[0190] The pattern formation method of the black resist layer
contains a black resist layer forming step of coating a black
resist composition on a substrate to form a black resist layer
composed of the resist composition, an exposing step of exposing
this black resist layer via a mask, and a developing step of
developing the black resist layer after exposure to form a light
shielding pattern. The pattern formation may be arbitrarily carried
out before fabrication of a lens or after fabrication of a
lens.
[0191] The steps in the production method of the present invention
will be explained below.
<Black Resist Layer Forming Step>
[0192] In the black resist layer forming step, a black resist
composition is coated on the surface of the lens module having the
substrate 1 on which a plurality of lenses 10 have been formed,
thereby forming a black resist layer 14 of low light reflection
rate composed of the resist composition. In this case, the black
resist layer 14 is formed to cover all of the surface of the
substrate part, and the lens surface 10a of the lens 10 and the
lens marginal part 10b, on the surface of the lens module.
[0193] The substrate 1 used in this step is not particularly
restricted. Examples thereof include soda glass, Pyrex (registered
trademark) glass, quartz glass and transparent resins, and the
like.
[0194] On the substrate 1, a primer layer may be provided if
necessary, for improvement of close adhesion to the upper layer,
prevention of substance scattering, or flattening of the surface of
the substrate 1.
[0195] For coating the black resist composition, various coating
methods can be used such as slit coating, spray coating, inkjet,
rotation coating, cast coating, roll coating, screen printing and
the like. For obtaining excellent film thickness, spray coating is
preferable. Spray coating is preferable also for obtaining low
reflection rate.
[0196] As preferable conditions for spray-coating the black resist
composition, a composition having a solid content of 10% to 40% is
used, coated at a rate of 0.01 cc to 10 ccc per minute, and coated
with a distance of 1 cm to 30 cm from the substrate 1. The diameter
of a nozzle for spray coating is preferably 0.05 mm to 1 mm.
[0197] The thickness of the black resist composition directly after
coating is preferably 0.1 .mu.m to 20 .mu.m, further preferably 0.1
.mu.m to 10 .mu.m, more preferably 0.2 .mu.m to 10 .mu.m,
particularly preferably 0.2 .mu.m to 5 .mu.m, most preferably 0.2
.mu.M to 3 .mu.m, from the standpoint of thickness uniformity of
the coated film and easiness of drying of the coating solvent.
[0198] In the case of use of a spray coating method, the thickness
of the black resist composition and uniformity of the black resist
layer can be adjusted by appropriately controlling the spray
pressure condition, the discharge amount of the black resist
composition, the kind of the spray nozzle, the distance between the
lens substrate and the spray nozzle, and the like. The spray
coating apparatus which can be used in the present invention
includes Nanospray manufactured by EVG, AltaSpray manufactured by
SUSS, Resist Spray Coater RS-C810A manufactured by TechinTech Co.,
Ltd., TS-MSP-400, TS-MSP-300, TS-MSP-200 and TS-MSP-100
manufactured by TAITECH Corporation, USC-2000ST manufactured by
USHIO Inc., and the like.
[0199] Drying (prebake) of the coated black resist layer 14 (resist
composition layer) can be carried out by a hot plate, an oven and
the like at a temperature of 50.degree. C. to 140.degree. C. for 10
seconds to 300 seconds.
[0200] The coated thickness after drying of the black resist
composition (hereinafter, referred appropriately to as "dried film
thickness") can be arbitrarily selected based on desired
performances such as a light shielding property and the like, and,
in general, in the range of 0.1 .mu.m or more and less than 50
.mu.m.
<Exposing Step>
[0201] In the exposing step, the black resist layer 14 (resist
composition layer) formed in the above-described black resist layer
forming step is exposed in the form of pattern using
photolithography. Though the pattern exposure may be scanning
exposure, an embodiment of carrying out exposure via a mask 70
having a prescribed mask pattern as shown in FIG. 7B is
preferable.
[0202] In exposure of this step, the black resist layer 14 is
pattern-exposed via a prescribed mask pattern, and only parts of
the black resist layer 14 irradiated with a light are cured. Here,
a mask pattern allowing irradiation with a light on the surface of
the lens marginal part 10b and the surface of the substrate 1
between the lenses 10 is used. By this, only regions of the black
resist layer 14 excluding the lens surface 10a are cured by light
irradiation. As radiations which can be used in exposure,
particularly, ultraviolet rays such as g line, h line, i line and
the like are preferably used. For this radiation, a light source of
single wavelength may be used, or a light source including all
wavelengths such as a high pressure mercury lamp may be used.
<Developing Step>
[0203] Then, by carrying out an alkali developing treatment
(developing step), parts of no irradiation by the above-described
exposure are dissolved in an alkali aqueous solution, leaving only
photo-cured parts. In this example, only the black resist layer 14
formed on the lens surface 10a is removed, and the black resist
layer 14 remains on other regions (see, FIG. 7C). As the alkali
agent, organic or inorganic alkali agents and combinations thereof
can be used. In the present invention, organic alkali developing
liquids causing no damages on surrounding circuits and the like are
desirable.
[0204] Examples of the alkali agent used in the developing liquid
include organic alkaline compounds such as ammonia water,
ethylamine, diethylamine, dimethylethanolamine, tetramethylammonium
hydroxide, tetraethylammonium hydroxide, choline, pyrrole,
piperidine, 1,8-diazabicyclo-[5.4.0]-7-undecene and the like,
inorganic compounds such as sodium hydroxide, potassium hydroxide,
sodium hydrogen carbonate, potassium hydrogen carbonate and the
like, and alkaline aqueous solutions prepared by diluting these
alkali agents with pure water so as to give a concentration of
0.001 wt % to 10 wt %, preferably 0.01 wt % to 1 wt % can be
preferably used as the developing liquid. It is also possible to
add alcohols and surfactants in suitable amount to the
above-described alkaline aqueous solution.
[0205] In the case of use of a developing liquid composed of such
an alkaline aqueous solution, washing with pure water (rinse) is
generally performed after development.
[0206] As the developing method, for example, a method (dip method)
of immersing a substrate for a certain time in a bath filled with a
developing liquid, a method (paddle method) of lifting a developing
liquid on the surface of a substrate by surface tension and
allowing it to stand still for a certain time, thereby attaining
development, a method (spray method) of spraying a developing
liquid on the surface of a substrate, a method (dynamic dispense
method) of continuously discharging a developing liquid on a
substrate rotating at constant speed while scanning a developing
liquid discharge nozzle at constant speed, and the like, can be
applied.
[0207] The developing temperature is usually 20.degree. C. to
30.degree. C. and the developing time is in the range of 20 seconds
to 90 seconds.
[0208] Then, an excess developing liquid is removed by washing, and
drying is carried out.
[0209] After carrying out the above-described black resist layer
forming step, exposing step and developing step in the production
method of this example, a curing step of curing the formed
shielding pattern by heating (post bake) and/or exposure may also
be contained, if necessary.
[0210] Post bake is a heating treatment after development for
completing curing, and usually, a thermal curing treatment at
100.degree. C. to 250.degree. C. is carried out. Conditions such as
the temperature of post bake and the time thereof can be
appropriately set by selecting the material of the substrate or the
lens. For example, when the substrate is made of glass,
temperatures of 180.degree. C. to 240.degree. C. are suitably used
among the above-described temperature range.
[0211] This post bake treatment can be carried out in continuous
mode or batch mode on the black resist layer 14 after development
by using a heating means such as a hot plate, a convection oven
(hot air circulation mode drier), a high frequency wave heating
machine and the like so as to obtain the above-described
conditions.
[0212] The energy-curable resin composition used in the wafer level
lens may be any of resin compositions cured by heat or resin
compositions cured by irradiation with an active energy ray (for
example, ultraviolet ray, electron beam).
[0213] It is preferable that the material has suitable flowability
before curing from the standpoint of molding properties such as
transfer suitability of a mold shape and the like. Specifically,
those which are liquid and having a viscosity of about 1000 to
50000 mPas at ambient temperature are preferable.
[0214] It is preferable that the material has heat resistance after
curing with which thermal deformation does not occur even through a
reflow process. From this standpoint, the glass transition
temperature after curing is preferably 200.degree. C. or higher,
more preferably 250.degree. C. or higher, particularly preferably
300.degree. C. or higher. For imparting such high heat resistance
to the resin composition, the mobility at molecule level should be
suppressed, and effective methods thereof include (1) a method of
enhancing cross-linkage density per unit volume, (2) a method of
utilizing a resin having a rigid cyclic structure (for example,
alicyclic structures such as cyclohexane, norbornane,
tetracyclododecane and the like, aromatic cyclic structures such as
benzene, naphthalene and the like, curd structures such as
9,9'-biphenylfluorene and the like, resins having a Spiro structure
such as spirobiindane and the like, specifically, resins described
in, for example, JP-A Nos. 9-137043 and 10-67970, JP-A Nos.
2003-55316, 2007-334018 and 2007-238883, and the like), (3) a
method of uniformly dispersing a substance of high Tg such as
inorganic fine particles and the like (described in, for example,
JP-A Nos. 5-209027 and 10-298265, and the like), and the like.
These methods may be combined, and preferably controlled in a range
not deteriorating other properties such as flowability, shrinkage
ratio, refractive index property and the like.
[0215] Resin compositions showing small volume shrinkage rate by a
curing reaction are preferable from the standpoint of shape
transfer precision. The curing shrinkage ratio of the resin
composition used in the present invention is preferably 10% or
less, more preferably 5% or less, particularly preferably 3% or
less.
[0216] Examples of the resin composition showing a low cure
shrinkage ratio include (1) resin compositions containing a high
molecular weight curing agent (prepolymer and the like) (described
in, for example, JP-A Nos. 2001-19740, 2004-302293 and 2007-211247,
and the like, the number average molecular weight of the high
molecular weight curing agent is in the range of preferably 200 to
100000, more preferably 500 to 50000, particularly preferably 1000
to 20000. The value calculated by dividing the number average
molecular weight of the curing agent by the number of cure reactive
groups is in the range of preferably 50 to 10000, more preferably
100 to 5000, particularly preferably 200 to 3000), (2) resin
compositions containing a nonreactive substance (organic/inorganic
fine particle, nonreactive resin and the like) (described in, for
example, JP-A Nos. 6-298883, 2001-247793 and 2006-225434, and the
like), (3) resin compositions containing a low shrinkage
crosslink-reactive group (for example, ring-opening polymerizable
groups (for example, epoxy groups (described in, for example, JP-A
No. 2004-210932 and the like), oxetanyl groups (described in, for
example, JP-A No. 8-134405 and the like), episulfide groups
(described in, for example, JP-A No. 2002-105110 and the like),
cyclic carbonate groups (described in, for example, JP-A No.
7-62065 and the like) and the like), ene/thiol curing groups
(described in, for example, JP-A No. 2003-20334 and the like),
hydrosilylated curing groups (described in, for example, JP-A No.
2005-15 666 and the like) and the like), (4) resin compositions
containing a rigid skeleton resin (fluorene, adamantane, isophorone
and the like) (described in, for example, JP-A No. 9-137043 and the
like), (5) resin compositions containing two monomers of different
polymerizabilities thereby forming an interpenetrating polymer
network structure (so called IPN structure) (described in, for
example, JP-A No. 2006-131868 and the like), (6) resin compositions
containing an expansible substance (described in, for example, JP-A
No. 2004-2719, JP-A No. 2008-238417 and the like), and the like,
and these compositions can be suitably used in the present
invention. It is preferable to use some of the above-described cure
shrinkage reducing means together (for example, resin compositions
containing fine particles and a prepolymer having a ring-opening
polymerizable group, and the like) from the standpoint of
optimization of physical properties.
[0217] The wafer level lens of the present invention contains resin
compositions having higher and lower two different Abbe's
numbers.
[0218] The resin of the higher Abbe's number side has an Abbe's
number (.nu.d) of preferably 50 or more, more preferably 55 or
more, particularly preferably 60 or more. The refractive index (nd)
is preferably 1.52 or more, more preferably 1.55 or more,
particularly preferably 1.57 or more.
[0219] As such resins, aliphatic resins are preferable, and
particularly, resins having an alicyclic structure (for example,
resins having a cyclic structure such as cyclohexane, norbornane,
adamantane, tricyclodecane, tetracyclododecane and the like,
specifically, resins described in, for example, JP-A No. 10-152551,
JP-A Nos. 2002-212500, 2003-20334, 2004-210932, 2006-199790,
2007-2144, 2007-284650 and 2008-105999, and the like) are
preferable.
[0220] The resin of the lower Abbe's number side has an Abbe's
number (.nu.d) of 30 or less, more preferably 25 or less,
particularly preferably 20 or less. The refractive index (nd) is
preferably 1.60 or more, more preferably 1.63 or more, particularly
preferably 1.65 or more.
[0221] As such resins, resins having an aromatic structure are
preferable, and for example, resins containing a structure of
9,9'-diarylfluorene, naphthalene, benzothiazole, benzotriazole and
the like (specifically, resins described in, for example, JP-A No.
60-38411, JP-A No. 10-67977, JP-A Nos. 2002-47335, 2003-238884,
2004-83855, 2005-325331 and 2007-238883, International Publication
WO 2006/095610, Japanese Patent No. 2537540 and the like; etc.) are
preferable.
[0222] It is preferable to disperse inorganic fine particles in a
matrix in the resin of the present invention, for the purpose of
enhancing refractive index and for the purpose of controlling
Abbe's number. Examples of the inorganic fine particles include
oxides fine particles, sulfides fine particles, selenide fine
particles and telluride fine particles. More specific examples
thereof include fine particles of zirconium oxide, titanium oxide,
zinc oxide, tin oxide, niobium oxide, cerium oxide, aluminum oxide,
lanthanum oxide, yttrium oxide, zinc sulfide and the like.
[0223] Particularly in the above-described resin of higher Abbe's
number, fine particles of lanthanum oxide, aluminum oxide,
zirconium oxide and the like are preferably dispersed, and in the
resin of lower Abbe's number, fine particles of titanium oxide, tin
oxide, zirconium oxide and the like are preferably dispersed. The
inorganic fine particles may be used singly or in combination of
two or more of them. A composite composed of several components may
also be used. Further, the inorganic fine particles may be doped
with a dissimilar metal, the surface layer thereof may be covered
with a dissimilar metal oxide such as silica, alumina and the like,
or the surface thereof may be modified with a silane coupling
agent, a titanate coupling agent, an organic acid (carboxylic
acids, sulfonic acids, phosphoric acids, phosphonic acids and the
like) or a dispersing agent having an organic acid group, or the
like, for the purpose of reducing photocatalytic activity, reducing
water absorption coefficient, and the like. The number average
particle size of the inorganic fine particles may be usually 1 nm
to 1000 nm, and when the number average particle size is too small,
the properties of the substance may change in some cases, while
when too large, an influence by Rayleigh scattering becomes
remarkable, thus it is preferably 1 nm to 15 nm, further preferably
2 nm to 10 nm, particularly preferably 3 nm to 7 nm. It is
desirable that the inorganic fine particles have narrower particle
size distribution. Though the definition methods of such
monodispersed particles are various, for example, the numerical
value prescription range as described in JP-A No. 2006-160992 is a
preferable particle size distribution range. The above-described
number-average primary particle size can be measured, for example,
by an X-ray diffraction (XRD) instrument, a transmission electron
microscope (TEM) and the like. The refractive index of the
inorganic fine particles is preferably 1.90 to 3.00, further
preferably 1.90 to 2.70, particularly preferably 2.00 to 2.70 at a
temperature of 22.degree. C. and a wavelength of 589 nm. The
content of the inorganic fine particles in the resin is preferably
5 wt % or more, further preferably 10 to 70 wt %, particularly
preferably 30 to 60 wt %, from the standpoint of transparency and
enhanced refractive index.
[0224] For uniformly dispersing fine particles in the resin
composition, it is desirable to disperse fine particles by
appropriately using, for example, dispersing agents containing a
functional group having reactivity with a resin monomer forming a
matrix (described in, for example, JP-A No. 2007-238884 examples,
and the like), block copolymers constituted of a hydrophobic
segment and a hydrophilic segment (described in, for example, JP-A
No. 2007-211164), resins having a functional group which is capable
of forming any chemical bond to the inorganic fine particles at the
polymer end or side chain (described in, for example, JP-A No.
2007-238929, JP-A No. 2007-238930 and the like), and the like.
[0225] In the resin composition used in the present invention,
additives such as known releasing agents such as silicon compounds,
fluorine-based compounds, long chain alkyl group-containing
compounds and the like and antioxidants such as hindered phenol and
the like may be appropriately blended.
[0226] In the curable resin composition of the present invention,
curing catalysts or initiators can be blended if necessary.
Specifically, compounds promoting a curing reaction (radical
polymerization or ion polymerization) by the action of heat or
active energy ray described in, for example, JP-A No. 2005-92099
(paragraph numbers [0063] to [0070]) and the like are mentioned.
The addition amount of these curing reaction promoting agents
varies depending on the kind of the catalyst and the initiator and
difference in the curing reactive site and the like and cannot be
commonly determined, and in general, it is preferably about 0.1 to
15 wt %, more preferably about 0.5 to 5 wt % with respect to the
total solid content of the curing reactive resin composition.
[0227] The curing resin composition of the present invention can be
produced by appropriately blending the above-described components.
When other components can be dissolved in a liquid-state low
molecular weight monomer (reactive diluent) and the like, there is
no necessity to separately add a solvent, while when this case is
not applicable, a curable resin composition can be produced by
dissolving constituent components using a solvent. The solvent
which can be used in the curable resin composition is not
particularly restricted and can be appropriately selected providing
that it causes no precipitation of the composition and gives
uniform dissolution or dispersion, and specific examples thereof
include ketones (for example, acetone, methyl ethyl ketone, methyl
isobutyl ketone and the like), esters (for example, ethyl acetate,
butyl acetate and the like), ethers (for example, tetrahydrofuran,
1,4-dioxane and the like), alcohols (for example, methanol,
ethanol, isopropyl alcohol, butanol, ethylene glycol and the like),
aromatic hydrocarbons (for example, toluene, xylene and the like),
water and the like. When the curable composition contains a
solvent, it is preferable that the composition is cast on a
substrate and/or a mold, the solvent is dried, then, a mold shape
transfer operation is carried out.
[0228] Though the shape of the lens 10 is concave in the
above-described procedure, this shape is not particularly
restricted, and a convex shape and an aspherical shape may also be
used. In the above-described procedure, the wafer level lens has a
lens module having a plurality of lenses 10 molded on one surface
of the substrate 1, however, a constitution of a lens module having
a plurality of lenses molded on both surfaces thereof may also be
used, and in this case, the black resist layers 14 are formed with
a pattern having an opening at a part intersecting the optical axis
of a lens on both surfaces of the lens module.
[0229] FIG. 8 is a view showing another constitution example of a
wafer level lens. The wafer level lens of FIG. 8 has a constitution
(monolithic type) having a lens module in which the substrate 1 and
the lenses 10 are molded simultaneously from the same molding
material. As the molding material, the same material as described
above can be used. In this example, a plurality of concave-shaped
lenses 10 are formed on one surface (upper side surface in the
figure) of the substrate 1 and a plurality of convex-shaped lenses
20 are formed on another surface (lower side surface in the
figure). The black resist layer 14 is patterned on regions
excluding the lens surface 10a on the surface of the lens module,
that is, the surface of the substrate part and the surface of the
lens marginal part 10b. For patterning of the black resist layer
14, the procedure as describe above can be applied.
[0230] Next, another procedure for patterning the black resist
layer will be explained. In the above-described example, the black
resist layer is patterned on the substrate carrying thereon lenses,
while in the procedure explained below, a black resist layer is
patterned on a substrate, then, lenses are molded on the
substrate.
[0231] FIG. 9A to FIG. 9C are views showing another procedure of
patterning of a black resist layer. FIG. 10A to FIG. 10C are views
showing a procedure of molding lenses on a substrate carrying
thereon a patterned black resist layer.
[0232] First, a black resist layer forming step of spray-coating a
black resist composition on the substrate 1 to form the black
resist layer 14 composed of the resist composition as shown in FIG.
9A is carried out.
[0233] Then, the black resist layer 14 coated on the substrate 1 is
dried by a hot plate, an oven and the like at a temperature of
50.degree. C. to 140.degree. C. for 10 seconds to 300 seconds. The
dried thickness of the black resist layer can be arbitrarily
selected according to desired performances such as a light
shielding property and the like, and is generally in the range of
0.1 .mu.m or more and less than 50 .mu.m.
[0234] Next, an exposing step is carried out in which the black
resist layer 14 formed in the black resist layer forming step is
exposed in the form of pattern via a mask 70 as shown in FIG. 9B.
The mask 70 has a prescribed mask pattern. In exposure of this
step, pattern exposure of the black resist layer 14 can be carried
out by curing only parts irradiated with a light of the black
resist layer 14. Here, a mask pattern is used which allows
irradiation with a light only of the black resist layer 14 at
regions excluding a position of the lens opening 14a of the lens 10
when the lens 10 is molded in a latter step. By this, only regions
of the black resist layer 14 excluding a position of the lens
opening 14a of the lens 10 are cured by light irradiation. As
radiations which can be used in exposure, ultraviolet rays such as
g line, h line, i line and the like are preferably used as in the
above-described procedure.
[0235] Next, by carrying out an alkali developing treatment
(developing step), only the resist layer of a region corresponding
to the lens opening 14a of the lens 10 which is not cured by the
above-described exposure is dissolved in an alkali aqueous
solution. In contrast, the photo-cured black resist layer 14 at
regions excluding the region of the lens opening 14a of the lens 10
remain on the substrate (see, FIG. 9C). As the alkali agent, the
same agent as used in the procedure as described above can be used.
Then, an excess developing liquid is removed by washing, and drying
is carried out.
[0236] After carrying out the above-described black resist layer
forming step, exposing step and developing step in the production
method of this example, a curing step of curing the formed
shielding pattern by the above-described post bake and/or exposure
may also be contained, if necessary.
[0237] Next, the molding material M constituting the lens 10 is
dropped by the dispenser 50 on the substrate 1 on which the black
resist layer 14 has been patterned, as shown in FIG. 10A. The
molding material M is fed so as to cover a region corresponding to
the lens opening 14A of the lens 10 and to partially include the
end of the black resist layer 14 adjacent to the opening.
[0238] After feeding the molding material M on the substrate 1, a
mold 80 for molding a lens is disposed as shown in FIG. 10B. On the
mold 80, concave portions 82 for transferring the shape of the lens
10 are provided corresponding to the number of desired lenses
10.
[0239] The mold 80 is pushed to the molding material M on the
substrate 1, thereby deforming the molding material M to correspond
to the shape of the concave portion. Under the condition of pushing
the mold 80 to the molding material M, heat or ultraviolet ray is
irradiated from the outside of the mold to cure the molding resin M
when the molding resin M is a thermosetting resin or an ultraviolet
curable resin.
[0240] After molding of the molding material M, the substrate 1 and
the lens 10 can be released from the mold 80, to obtain a wafer
level lens having the black resist layer 14 patterned on the
substrate 1, as shown in FIG. 10C.
[0241] The black resist layer 14 formed on the wafer level lens is
not limited to the patterned form at a region excluding the lens
surface 10a of the lens 10 on the surface of the lens module, and
as shown in FIG. 10C, the lens opening 14a may also be formed at a
part intersecting the optical axis of the lens 10 on the surface of
the substrate. In the example of FIG. 10C, the black resist layer
14 functions as an optical diaphragm in the lens module, and the
diameter of the lens opening 14a is the effective diameter of the
lens 10.
[0242] In this wafer level lens, an incident light can be shielded
by the black resist layer 14 of low reflection rate patterned on
the surface of the lens module or the surface of the substrate, and
reflection of lights in the lens module and between the lens
modules can be suppressed. Because of this constitution, generation
of defects such as ghosts and flares due to a reflected light in
taking an image can be prevented when applied to an imaging module
having an imaging device.
[0243] Since the black resist layer 14 is patterned on the surface
of the substrate, there is no necessity to attach another light
shielding member and the like to the wafer level lens and an
increase in the production cost can be suppressed.
[0244] When a construction having an uneven surface is disposed
around a lens as in a structure shown in patent document 2, there
is a fear of tendency of generation of defects such as ghosts and
the like by reflection or radiation of an incident light in the
construction. In contrast, since the black resist layer 14 is
patterned on a region excluding the lens surface 10a of the lens 10
as shown in FIG. 2 in the wafer level lens of the present
invention, a light can be shielded at regions other than the lens
surface 10a and optical performances can be improved.
[0245] Next, the transmittance and the reflection rate of the black
resist layer were measured.
[0246] FIG. 11A is a transmission spectrum showing the
transmittance against the wavelength of an incident light. Here,
the black resist layer is formed with an average thickness of 3
.mu.m by spray coating on a glass wafer. As shown in FIG. 11A, it
is found that the transmittance of the black resist can be
suppressed to 0.4% or less for a visible light having a wavelength
of 400 to 700 nm.
[0247] FIG. 11B is a graph showing the reflection rate against the
wavelength of an incident light. Here, a film on which chromium was
vapor-deposited and a film on which chromium was spray-coated were
prepared, and a reflected light was measured along a direction
inclined by 5.degree. from the vertical direction to the glass
wafer surface. In FIG. 11B, the graph of the vapor-deposited film
is shown by a dashed line, and the graph of the spray-coated film
is shown by a dashed line. As shown in FIG. 11B, it is found that
the reflection rate of the spray-coated film can be lower than that
of the vapor-deposited film for a visible light having a wavelength
of 400 to 700 nm, and its reflection rate can be suppressed to 1%
or less. Further, it is found preferable to form a black resist
layer particularly by spray coating.
[0248] Next, another constitution example of the wafer level lens
will be explained.
[0249] FIG. 12 is a cross-sectional view showing another
constitution example of the wafer level lens. FIG. 12 is a
cross-sectional view corresponding to the line A-A cross-sectional
view of the wafer level lens shown in FIG. 1.
[0250] As shown in FIG. 12, a plurality of concave-shaped lenses 10
are disposed on one surface of the substrate 1, and a plurality of
lenses 20 having a lens surface 20a protruding in a convex shape
are disposed on another surface thereof. The lens 10 has a
concave-shaped lens surface 10a and a lens marginal part 10b around
the lens surface 10a. Here, the lens surface 10a has an optical
property of concentrating or radiating an incident light in the
lens 10 toward a desired direction, and the curvature and the
surface shape thereof are designed in view of this optical
property. In this example, the height of the lens marginal part 10b
from the substrate 1 is higher than the center of the lens surface
10a.
[0251] This lens module is molded so that the optical axis of each
lens 10 on one surface of the substrate and the optical axis of the
lens 20 on another surface thereof coincide.
[0252] The shape of the lenses 10 and 20 is not particularly
restricted, and for example, a lens having a lens surface 10a
protruding in a convex shape, that is, a convex-shaped lens may be
used, or an aspherical lens may also be used.
[0253] In this lens module, a light shielding layer 24 is provided
so as to cover the surface of the lens marginal part 10b of the
lens 10 and the surface of the substrate 1 between the lenses 10.
The light shielding layer 24 is patterned on a region excluding the
lens surface 10a of the lens 10, on the surface of the lens module.
When the wafer level lens has a constitution of lamination of two
or more lens modules, the light shielding layer 24 is provided on
the surface of the lens module situated at the outermost position
of the incident side. The light shielding layer 24 is formed with a
pattern having an opening at a part intersecting the optical axis
of the lens 10. The light shielding layer 24 may partially cover a
peripheral part of the lens surface 10a.
[0254] The light shielding layer 24 has a reflection rate of 4% or
less and a transmittance of 0.1% or less for a visible light having
a wavelength of 400 to 700 nm.
[0255] The light shielding layer 24 contains a metal material, and
has lower transmittance and higher reflection rate for a visible
light than that of a low reflection light shielding layer described
later. Since the light shielding layer 24 is disposed on a region
other than the lens surface 10a of the lens 10 of the substrate 1,
it has a function of reflecting a light irradiated on regions other
than the lens surface 10a. By this constitution, an incident light
is shielded on regions other than the lens surface 10a of the lens
10 by the light shielding layer 24. The metal material contained in
the light shielding layer 24 will be described later.
[0256] A low reflective light shielding layer 14 is disposed on a
region excluding the lens surface 20a of the lens 20, on the
surface opposite to the surface carrying thereon the light
shielding layer 24 of the lens module. The low reflective light
shielding layer 14 may partially cover a peripheral part of the
lens surface 20a.
[0257] Since the low reflective light shielding layer 14 is
constituted of the above-described black resist layer and has a
light reflection rate lower than that of a metal layer and the
like, disadvantages such as ghosts, flares and the like due to
light reflection can be reduced.
[0258] FIG. 13 is a cross-sectional view showing a deformed example
of the wafer level lens shown in FIG. 12. FIG. 13 shows a condition
obtained by connecting a spacer to the substrate 1 of the lens
module, then, providing one lens 10 and one lens 20 on the
substrate 1 by dicing. The optical axis of the lens 10 and the
optical axis of the lens 20 coincide. The spacer 12 may also be
integrally molded to the substrate 1 as a part of the substrate 1.
This lens module can be connected to another lens module
sandwiching the spacer 12. This lens module can be connected to a
sensor substrate sandwiching the spacer 12.
[0259] In the constitution shown in FIG. 13, the light shielding
layer 24 is disposed on a region excluding the lens surface 10a of
the lens 10, on the surface of the light incident side of the lens
module. On the surface of the substrate 1 on which the lens 20 is
disposed, the low reflective light shielding layer 14 is formed
with a pattern having an opening at the lens surface 20a of the
lens 20.
[0260] FIG. 14 is a cross-sectional view showing an imaging unit
having the lens modules of FIG. 12.
[0261] In the lens module LM1, a convex-shaped lens 10A is molded
on the upper surface of the substrate 1A, and a lens 20A having a
concave-shaped lens surface is molded on the lower surface. On the
upper surface of the substrate 1A, a light shielding layer 24 is
patterned on a region excluding the lens surface of the lens 10A.
On the lens 20A, a low reflective light shielding layer 14 is
patterned on a region excluding the lens surface. Here, the upper
surface of the lens module LM1 is the light incident side outermost
surface. The light shielding layer 24 is disposed on at least a
part of this surface. The shape of patterning of the low reflective
light shielding layer 14 and the light shielding layer 24 is not
restricted, and the low reflective light shielding layer 14 and the
light shielding layer 24 may be formed with a pattern having an
opening at a part intersecting the optical axis of the lens, and
the same shall apply to the low reflective light shielding layer 14
of the lens modules LM2 and 3.
[0262] In the lens module LM2, a concave-shaped lens 10B is molded
on the upper surface of the substrate 1B, and a lens 20B having a
convex-shaped lens surface is molded on the lower surface. This
lens module LM2 has basically the same constitution as shown in
FIG. 3. A patterned low reflective light shielding layer 14 is
disposed on a region excluding the lens surface of the lens 10B on
the surface of the lens module LM2, that is, on the lens marginal
part and a region of no lens 10B on the surface of the substrate
1B. In this example, the low reflective light shielding layer 14 is
not disposed on the lower surface of the substrate 1B, however, a
patterned low reflective light shielding layer 14 may be disposed
on a region excluding the lens surface of the lens 20B.
[0263] In the lens module LM3, an aspherical-shaped lens 10C is
molded on the upper surface of the substrate 1C, and a lens 20C
having an aspherical-shaped lens surface is molded on the lower
surface. On both surfaces of the lens module LM3, the patterned low
reflective light shielding layer 14 is disposed on a region
excluding the lens surfaces of the lens 10C and the lens 20C. The
low reflective light shielding layer 14 may be provided on the
surfaces of the substrates 1A, 1B and 1C of the lens modules LM1,
LM2 and LM3, respectively, or may be provided on some of the
surfaces of the substrates 1A, 1B and 1C. The low reflective light
shielding layer 14 may advantageously be formed with a pattern
having an opening at a part intersecting the optical axis of the
lenses 10A, 10B and 10C, on the surfaces of the lens modules LM1,
LM2 and LM3 or the surfaces of the substrates 1A, 1B and 1C.
[0264] In this imaging unit, other members and constitutions are as
shown in FIG. 4.
[0265] In the case of a constitution of lamination of the lens
modules LM1, LM2 and LM3 as shown in FIG. 14, the light shielding
layer 24 is provided on the surface of the top lens module LM1
closest to the light incident side or on the surface of the
substrate 1A. The light shielding layer 24 has lower transmittance
and higher light reflection rate than the low reflective light
shielding layer 14, and has a reflection rate of 4% or less and a
transmittance of 0.1% or less for a visible light having a
wavelength of 400 to 700 nm.
[0266] The light shielding layer 24 is formed on an at least
partial region of the surface of the lens module LM1 situated at
the light incident side outermost position. As shown in FIG. 14,
the light shielding layer 24 is formed with a pattern having an
opening at a part intersecting the optical axis of the lens, on the
surface of the substrate of the lens module LM1 situated at the
light incident side outermost position, and its opening may
function as an optical diaphragm corresponding to the effective
diameter of the lens A.
[0267] This wafer level lens has the light shielding layer 24 and
the low reflective light shielding layer 14. The light shielding
layer 24 has a function of preventing transmission of a light in
the substrate, by reflecting a light incoming from the outside of
the wafer level lens. Particularly when a plurality of substrates
are disposed, a light incoming from the top substrate surface is
reflected by the light shielding layer 24 at a region other than
the lens, and it is possible to prevent the light penetrated
through a region other than the lens from penetrating between the
substrates and to the sensor substrate side.
[0268] By providing the low reflective light shielding layer 14,
transmission of a light at a region other than the lens surface of
the lens can be prevented.
[0269] By providing both the light shielding layer 24 and the low
reflective light shielding layer 14, a light penetrating a part
other than the lens can be reflected by the light shielding layer
24, and even if a light penetrates into the substrate without
reflection by the light shielding layer 24, the light can be
shielded by the low reflective light shielding layer 14.
Accordingly, generation of light transmission and reflection at a
region other than the lens surface of the lens can be prevented,
and defects in optical performances such as ghosts and flares in
taking an image can be suppressed.
[0270] Further, since the light shielding layer 24 and the low
reflective light shielding layer 14 are formed on the surface of
the substrate, there is no necessity to attach another light
shielding member and the like to the wafer level lens and an
increase in the production cost can be suppressed.
[0271] The low reflective light shielding layer 14 can be formed by
the same procedure as for the above-described black resist layer.
That is, before formation of a lens on a substrate, a black resist
layer is coated on the surface of the substrate, the coated black
resist layer is formed with a pattern having an opening at a part
intersecting the optical axis of the lens, then, the lens is
integrally molded with the substrate, thus, the low reflective
light shielding layer can be formed.
[0272] Alternatively, the low reflective light shielding layer may
also be obtained by a method in which the above-described lens is
molded on a substrate, a black resist layer is coated on the lens
surface of the lens and the surface of the substrate, and the black
resist layer is formed with a pattern having an opening at a part
intersecting the optical axis of the lens. Also the light shielding
layer can be formed by the same manner as for the low reflective
light shielding layer.
[0273] It is preferable that the low reflective light shielding
layer is formed particularly by spray coating as shown in FIG.
11.
[0274] The present specification discloses the following
contents.
[0275] (1) A wafer level lens having at least one lens module
having a substrate and a plurality of lenses formed on said
substrate, in which the wafer level lens has a black resist layer
formed on the surface of said lens module or on the surface of said
substrate, and said black resist layer is formed with a pattern
having an opening at a part intersecting the optical axis of said
lens.
[0276] (2) A wafer level lens having at least one lens module
having a substrate and a plurality of lenses formed on said
substrate, in which the wafer level lens has a light shielding
layer formed on an at least partial region of the light incidence
side outermost surface of said lens module and a low reflective
light shielding layer formed with a pattern having an opening at a
part intersecting the optical axis of said lens, on the surface of
said lens module or on the surface of said substrate other than
said light incidence side outermost surface, and said light
shielding layer has lower transmittance for a visible light and
higher reflection rate than said low reflective light shielding
layer.
[0277] (3) The wafer level lens according to (2), in which said low
reflective light shielding layer is a black resist layer.
[0278] (4) The wafer level lens according to (1) or (3), in which
said black resist layer is formed using a black resist
composition.
[0279] (5) The wafer level lens according to any one of (1), (3)
and (4), in which said black resist layer contains any one of
carbon black, silver-tin and titanium black.
[0280] (6) The wafer level lens according to any one of (1), (3) to
(5), in which said black resist layer has a reflection rate of 2%
or less and a transmittance of 1% or less for visible light having
a wavelength of 400 to 700 nm.
[0281] (7) The wafer level lens according to (2), in which said
light shielding layer contains a metal material.
[0282] (8) The wafer level lens according to (2) or (7), in which
said light shielding layer contains chromium.
[0283] (9) The wafer level lens according to any one of (2), (7)
and (8), in which said light shielding layer has a reflection rate
of 4% or less and a transmittance of 0.1% or less for visible light
having a wavelength of 400 to 700 nm.
[0284] (10) The wafer level lens according to any one of (1) to
(9), in which a plurality of said lens modules are laminated via a
spacer formed on said substrate.
[0285] (11) An imaging unit having lens modules obtained by
separating said substrate of said lens module according to any one
of (1) to (10) so that each module contains said lens, an imaging
device, and a sensor substrate on which said imaging device is
disposed.
[0286] (12) A method of producing a wafer level lens having at
least one lens module having a substrate and a plurality of lenses
formed on said substrate, in which before formation of said lenses
on said substrate, a black resist layer is coated on the surface of
the substrate, said coated black resist layer is formed with a
pattern having an opening at a part intersecting the optical axis
of said lens, then, said lens is integrally molded on said
substrate.
[0287] (13) A method of producing a wafer level lens having at
least one lens module having a substrate and a plurality of lenses
formed on said substrate, in which said lens is molded on said
substrate, a black resist layer is coated on the lens surface of
said lens and on the surface of said substrate, and said black
resist layer is formed with a pattern having an opening at a part
intersecting the optical axis of said lens.
[0288] (14) The production method of a wafer level lens according
to (13), in which said black resist layer is coated by a spray
coating method.
[0289] (15) The production method of a wafer level lens according
to any one of (12) to (14), in which said black resist layer is
patterned by photolithography.
[0290] (16) The production method of a wafer level lens according
to any one of (12) to (15), in which said lens is molded on said
substrate with a mold.
[0291] (17) The production method of a wafer level lens according
to any one of (12) to (16), in which said black resist layer is
formed using a black resist composition.
[0292] (18) The production method of a wafer level lens according
to any one of (12) to (17), in which said black resist layer
contains any one of carbon black, silver-tin and titanium
black.
[0293] (19) The production method of a wafer level lens according
to any one of (12) to (18), in which said black resist layer has a
reflection rate of 2% or less and a transmittance of 1% or less for
visible light having a wavelength of 400 to 700 nm.
[0294] (20) The production method of a wafer level lens according
to any one of (12) to (19), in which a plurality of said lens
modules are laminated via a spacer formed on said substrate.
INDUSTRIAL APPLICABILITY
[0295] The above-described wafer level lens and imaging unit can be
applied in producing an imaging lens provided on an imaging part of
digital cameras, endoscopic instruments, portable electronic
instruments and the like.
[0296] Though the present invention was explained in detail or
referring to specific embodiments, it is apparent to those skilled
in the art that various changes and modifications can be made
without deviating from the spirit and the scope of the present
invention.
[0297] The instant application is based on Japanese Patent
Application filed on Aug. 13, 2009 (Japanese Patent Application No.
2009-187858), Japanese Patent Application filed on Sep. 9, 2009
(Japanese Patent Application No. 2009-208365), Japanese Patent
Application filed on Sep. 9, 2009 (Japanese Patent Application No.
2009-208366), Japanese Patent Application filed on Sep. 9, 2009
(Japanese Patent Application No. 2009-208367), Japanese Patent
Application filed on Aug. 11, 2010 (Japanese Patent Application No.
2010-180625), Japanese Patent Application filed on Aug. 11, 2010
(Japanese Patent Application No. 2010-180626), Japanese Patent
Application filed on Aug. 11, 2010 (Japanese Patent Application No.
2010-180627) and Japanese Patent Application filed on Aug. 11, 2010
(Japanese Patent Application No. 2010-180628), the contents thereof
being incorporated herein by reference.
EXPLANATION OF MARKS
[0298] 1: Substrate [0299] 10: Lens [0300] 14: Black resist layer
(low reflective light shielding layer) [0301] 24: Light shielding
layer
* * * * *