U.S. patent application number 16/020434 was filed with the patent office on 2019-03-21 for meta-surface optical element and method of manufacturing the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Seunghoon HAN, Jaekwan KIM, Yongsung KIM, Changseung LEE, Jeongyub LEE, Byunghoon NA, Jangwoo YOU.
Application Number | 20190086579 16/020434 |
Document ID | / |
Family ID | 63579231 |
Filed Date | 2019-03-21 |
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United States Patent
Application |
20190086579 |
Kind Code |
A1 |
KIM; Jaekwan ; et
al. |
March 21, 2019 |
META-SURFACE OPTICAL ELEMENT AND METHOD OF MANUFACTURING THE
SAME
Abstract
Provided are meta-surface optical device and methods of
manufacturing the same. The meta-surface optical device may include
a meta-surface arranged on a region of a substrate and a light
control member arranged around the meta-surface. The light control
member may be arranged on or below the substrate. A material layer
formed of the same material used to form the meta-surface may be
disposed between the light control member and the substrate. Also,
the meta-surface may be a first meta-surface arranged on an upper
surface of the substrate, and a second meta-surface may be arranged
on a bottom surface of the substrate. Also, the meta-surface may
include a first meta-surface and at least one second meta-surface
may formed on the first meta-surface, and the light control member
may be arranged around the at least one second meta-surface.
Inventors: |
KIM; Jaekwan; (Hwaseong-si,
KR) ; LEE; Jeongyub; (Yongin-si, KR) ; HAN;
Seunghoon; (Seoul, KR) ; KIM; Yongsung;
(Suwon-si, KR) ; NA; Byunghoon; (Suwon-si, KR)
; YOU; Jangwoo; (Seoul, KR) ; LEE; Changseung;
(Yongin-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
63579231 |
Appl. No.: |
16/020434 |
Filed: |
June 27, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 5/005 20130101;
G02B 5/1814 20130101; B82Y 20/00 20130101; G02B 27/4211 20130101;
G02B 1/002 20130101 |
International
Class: |
G02B 1/00 20060101
G02B001/00; G02B 27/42 20060101 G02B027/42 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2017 |
KR |
10-2017-0121873 |
Claims
1. A meta-surface optical device comprising: a substrate; a
meta-surface disposed on the substrate; and a light control member
arranged around the meta-surface.
2. The meta-surface optical device of claim 1, wherein the light
control member is disposed on the substrate.
3. The meta-surface optical device of claim 1, wherein the
meta-surface is disposed on an upper surface of the substrate, and
the light control member is disposed on a bottom surface of the
substrate.
4. The meta-surface optical device of claim 2, further comprising a
material layer disposed between the light control member and the
substrate, wherein a material of the material layer is the same as
a material of the meta-surface.
5. The meta-surface optical device of claim 2, further comprising a
material layer completely covering a surface of the light control
member.
6. The meta-surface optical device of claim 1, wherein the
meta-surface is a first meta-surface disposed on an upper surface
of the substrate, and wherein the meta-surface optical device
further comprises a second meta-surface disposed on a bottom
surface of the substrate.
7. The meta-surface optical device of claim 1, wherein: the
meta-surface is a first meta-surface, the meta-surface optical
device further comprises at least one second meta-surface stacked
on the first meta-surface, and the light control member is arranged
around the at least one second meta-surface.
8. The meta-surface optical device of claim 1, wherein the light
control member is one of a light absorption layer and a light
reflection layer.
9. The meta-surface optical device of claim 1, wherein the light
control member comprises a plurality of patterns configured to
perform a first operation with respect to light incident thereon,
and the meta-surface is configured to perform a second operation,
different from the first operation, with respect to light incident
thereon.
10. The meta-surface optical device of claim 9, wherein the
plurality of patterns of the light control member is configured to
reflect the light incident thereon and the meta-surface is
configured to refract the light incident thereon.
11. The meta-surface optical device of claim 9, wherein the
plurality of patterns of the light control member is configured to
absorb the light incident thereon and the meta-surface is
configured to refract the light incident thereon.
12. The meta-surface optical device of claim 1, wherein the light
control member comprises a first plurality of patterns, configured
to perform a first operation with respect to light incident
thereon, and a second plurality of patterns, configured to perform
a second operation, different from the first operation, with
respect to light incident thereon, and wherein the meta-surface is
configured to perform a third operation, different from the first
operation and the second operation, with respect to light incident
thereon.
13. The meta-surface optical device of claim 4, wherein the
material layer comprises a plurality of alignment key patterns.
14. The meta-surface optical device of claim 6, further comprising
a second light control member arranged around the second
meta-surface.
15. The meta-surface optical device of claim 6, wherein the second
meta-surface comprises a plurality of patterns configured to
perform a first operation with respect to light incident thereon
and wherein the first meta-surface comprises a plurality of
patterns configured to perform a second operation, different from
the first operation, with respect to light incident thereon.
16. The meta-surface optical device of claim 1, further comprising
a gap between the meta-surface and the light control member,
wherein a width of the gap is less than or equal to 5 .mu.m.
17. The meta-surface optical device of claim 1, wherein the
meta-surface and the light control member overlap with each other,
and a width of overlap between the meta-surface and the light
control member is less than or equal to 9 .mu.m.
18. A method of manufacturing a meta-surface optical device, the
method comprising: forming a meta-surface on a substrate; and
forming a light control member around the meta-surface.
19. The method of claim 18, wherein the forming the meta-surface
comprises forming the meta-surface on an upper surface of the
substrate and the forming the light control member comprises
forming the light control member separated from the upper surface
of the substrate.
20. The method of claim 18, wherein the forming the meta-surface
comprises forming the meta-surface on an upper surface of the
substrate and the forming the light control member comprises
forming the light control member contacting the upper surface of
the substrate.
21. The method of claim 18, wherein the forming the meta-surface
comprises forming the meta-surface on an upper surface of the
substrate and the forming the light control member comprises
forming the light control member on a bottom surface of the
substrate.
22. The method of claim 18, wherein the forming the meta-surface
comprises forming the meta-surface on an upper surface of the
substrate and the forming the light control member comprises
forming a first light control member above the substrate and
forming a second light control member below the substrate.
23. The method of claim 18, wherein the forming the meta-surface on
the substrate comprises sequentially forming a first meta-surface
and forming a second meta-surface.
24. The method of claim 18, wherein the forming the meta-surface
comprises forming a first meta-surface above the substrate and
forming a second meta-surface below the substrate.
25. The method of claim 18, wherein the forming the meta-surface
comprises forming the meta-surface on a first surface of the
substrate and the forming the light control member comprises
forming the light control member on the first surface of the
substrate.
26. The method of claim 18, wherein the forming the meta-surface
comprises forming the meta-surface on a first surface of the
substrate and the forming the light control member comprises
forming the light control member on a second surface of the
substrate, different from the first surface.
27. The method of claim 26, wherein the forming the light control
member further comprises forming a first portion of the light
control member, wherein the first portion is configured to perform
a first operation with respect to light incident thereon and
forming a second portion of the light control member, wherein the
second portion is configured to perform a second operation,
different form the first operation, with respect to light incident
thereon.
28. The method of claim 18, wherein the light control member
comprises one of a light absorption layer and a light reflection
layer.
29. The method of claim 18, wherein the light control member
comprises a plurality of patterns that absorb, reflect, or refract
light incident thereon.
30. The method of claim 18, wherein the forming the light control
member comprises forming the light control member such that the
light control member is separated from the meta-surface by a
separation distance that is less than or equal to 5 .mu.m.
31. The method of claim 18, wherein the forming the light control
member comprises forming the light control member to overlap with
the meta-surface, wherein a width of overlap between the light
control member and the meta-surface is less than or equal to 9
.mu.m.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Korean Patent
Application No. 10-2017-0121873, filed on Sep. 21, 2017, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND
1. Field
[0002] Apparatuses and methods consistent with exemplary
embodiments relate to optical elements, and more particularly, to
meta-surface optical elements and methods of manufacturing the
same.
2. Description of the Related Art
[0003] In order to overcome the limit of related art optical
techniques, a technique that uses a meta-surface has been
developed. When an optical part having a meta-surface is used, the
size of the element may be reduced, and also, optical efficiency
and resolution may be increased as compared to a conventional
optical element.
[0004] A meta-surface includes a plurality of patterns. Optical
characteristics of a meta-surface vary according to the specific
nano-structure patterns used in the meta-surface. A phase delay may
be created based on the radius of the patterns of the meta-surface,
and a lens may be realized using a meta-surface based on this phase
delay.
SUMMARY
[0005] One or more exemplary embodiments may provide meta-surface
optical elements configured to reduce a zero-order effect.
[0006] One or more exemplary embodiments may provide methods of
manufacturing the meta-surface optical elements.
[0007] Additional exemplary aspects will be set forth in part in
the description which follows and, in part, will be apparent from
the description, or may be learned by practice of the presented
exemplary embodiments.
[0008] According to an aspect of an exemplary embodiment, a
meta-surface optical element includes a substrate, a first
meta-surface arranged on a region of the substrate, and a light
control member arranged around the first meta-surface.
[0009] The light control member may be arranged on an upper surface
or a bottom surface of the substrate.
[0010] The meta-surface optical element may further include a
material layer, that is the same material as the first meta-surface
disposed between the light control member and the substrate.
[0011] The meta-surface optical element may further include a
material layer completely covering an upper surface of the light
control member.
[0012] The meta-surface optical element may further include a
second meta-surface on a bottom surface of the substrate.
[0013] At least one second meta-surface may be stacked on the first
meta-surface, and the light control member may be arranged around
the at least one second meta-surface.
[0014] The light control member may be a light absorption layer or
a light reflection layer.
[0015] The light control member may include a plurality of patterns
that perform a first operation with respect to light incident
thereon different from a second operation performed by the first
meta-surface with respect to light incident thereon.
[0016] The light control member may include a first plurality of
patterns that perform a first operation with respect to light
incident thereon and a second plurality of patterns that perform a
second operation, different from the first operation, with respect
to light incident thereon, and the first meta-surface may perform a
third operation, different from the first operation and the second
operation, with respect to light incident thereon.
[0017] The material layer may include alignment key patterns.
[0018] The meta-surface optical element may further include a
second light control member around the second meta-surface.
[0019] The second meta-surface may include a plurality of patterns
that perform an operation, with respect to light incident thereon,
different from an operation performed by the first meta-surface
with respect to light incident thereon.
[0020] The first meta-surface and the light control member having a
gap therebetween, the gap having a width less than six times a
wavelength of incident light. For example the width of the gap may
be equal to or less than 5 .mu.m.
[0021] The first meta-surface and the light control member may
overlap each other with a width of the overlap being less than ten
times a wavelength of incident light. For example, the width of the
overlap may be equal to or less than 9 .mu.m.
[0022] According to an aspect of another exemplary embodiment, a
method of manufacturing a meta-surface optical element is provided,
the method including forming a meta-surface on a substrate and
forming alight control member around the meta-surface.
[0023] The light control member may be separated from an upper
surface of the substrate.
[0024] The light control member may contact the upper surface of
the substrate.
[0025] The light control member may be formed on a bottom surface
of the substrate.
[0026] The light control member may be formed on and below the
substrate.
[0027] The forming of the meta-surface on the substrate may include
sequentially forming first and second meta-surfaces on the
substrate.
[0028] The method may further include forming another meta-surface
below the substrate.
[0029] The meta-surface and the light control member may be formed
on the same surface of the substrate.
[0030] The meta-surface and the light control member may be formed
on different surfaces from each other of the substrate.
[0031] The light control member may include a first part that
performs a first operation with respect to light incident thereon
and a second part that performs a second operation, different from
the first operation, with respect to light incident thereon.
[0032] The light control member may include a light absorption
layer or a light reflection layer.
[0033] The light control member may include patterns that absorb,
reflect, or refract incident light.
[0034] The light control member may be formed to be separate from
the meta-surface with a separation distance that is less than six
times of a wavelength of incident light. For example, the
separation distance may be less than or equal to 5 .mu.m.
[0035] The light control member and the meta-surface may overlap
with each other with an overlap width that is less than ten times
of a wavelength of incident light. For example, the overlap width
may be less than or equal to 9 .mu.m.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] These and/or other exemplary aspects and advantages will
become apparent and more readily appreciated from the following
description of exemplary embodiments, taken in conjunction with the
accompanying drawings in which:
[0037] FIGS. 1A through 1D are cross-sectional views of a method of
manufacturing a meta-surface optical device according to an
exemplary embodiment;
[0038] FIGS. 2A through 2C are cross-sectional views of a method of
manufacturing a meta-surface optical device according to another
exemplary embodiment;
[0039] FIG. 3A is a plan view of a meta-surface optical device
according to another exemplary embodiment;
[0040] FIG. 3B is a cross-sectional view taken along line 3B-3B' of
FIG. 3A;
[0041] FIGS. 3C and 3D are cross-sectional views of modifications
of the meta-surface optical device of FIG. 3B;
[0042] FIG. 3E is a cross-sectional view for explaining an
exemplary manufacturing process for obtaining the results of FIGS.
3C and 3D;
[0043] FIGS. 4A through 4C are cross-sectional views of a
meta-surface optical device according to another exemplary
embodiment;
[0044] FIGS. 5 through 13 are cross-sectional views respectively
showing operations of meta-surfaces and light control members
formed around the meta-surfaces with respect to incident light,
according to exemplary embodiments;
[0045] FIG. 14 is a cross-sectional view of a meta-surface optical
device according to another exemplary embodiment;
[0046] FIGS. 15A through 15D are cross-sectional views of an
exemplary method of manufacturing the meta-surface optical device
of FIG. 14;
[0047] FIG. 16 is a cross-sectional view of a meta-surface optical
device according to another exemplary embodiment;
[0048] FIGS. 17A through 17I are cross-sectional views of an
exemplary method of manufacturing the meta-surface optical device
of FIG. 16;
[0049] FIG. 18 is a cross-sectional view of a meta-surface optical
device according to another exemplary embodiment;
[0050] FIGS. 19A through 19E are cross-sectional views of an
exemplary method of manufacturing the meta-surface optical device
of FIG. 18;
[0051] FIGS. 20A through 20C are cross-sectional views of a
meta-surface optical device according to another exemplary
embodiment;
[0052] FIGS. 21A through 21G are cross-sectional views of an
exemplary method of manufacturing the meta-surface optical device
of FIG. 20A;
[0053] FIG. 22 is a cross-sectional view showing a case in which a
material layer having a high adhesion force with respect to a light
blocking layer is attached to a surface of a stamp to be attached
to a pattern region;
[0054] FIG. 23 is photographs showing an effect of the use of
meta-surface optical devices according to exemplary
embodiments;
[0055] FIG. 24 is a plan view of an exemplary correct alignment
between a meta-surface and a light control member;
[0056] FIG. 25 is a plan view of an exemplary incorrect alignment
between a meta-surface and a light control member;
[0057] FIG. 26 is a plan view of another exemplary incorrect
alignment between a meta-surface and a light control member;
[0058] FIGS. 27A, 27B, and 27C are photographs illustrating are
photographs illustrating three exemplary alignment states of
meta-surfaces and light control members;
[0059] FIGS. 28A, 28B, and 28C are photographs of structured
optical patterns obtained using meta surface optical devices
aligned as shown in FIGS. 27A, 27B, and 27C, respectively.
DETAILED DESCRIPTION
[0060] A meta-surface may be used for any of various applications.
However, an undesirable defect may occur as a result of an optical
part that includes only a meta-structure.
[0061] Commonly, peripheral light is blocked by an optical part
combining an aperture with a module.
[0062] In the case of a meta-surface optical part formed by using a
semiconductor process and an integration technique, the assembling
cost may be increased and precision may be reduced.
[0063] In particular, in the case of a structured optical pattern
like a meta-surface optical part used in a depth sensor, it is
important to reduce or remove light that is not used for forming
the structured optical pattern, that is, zero-order light or
zero-order noise.
[0064] Therefore, in the present exemplary embodiments, a
meta-surface optical device including a structure for reducing a
zero-order effect, that is, a structure for reducing the effect of
zero-order light in a diffractive optical element and a method of
manufacturing the meta-surface optical device are described. The
method of manufacturing the meta-surface optical element according
to the present exemplary embodiment includes (1) a method of using
an optical absorption material and (2) a method of forming a
multi-functional meta-surface.
[0065] Through combining the various methods described below,
various manufacturing methods and meta-surface optical devices may
be induced.
[0066] Meta-surface optical devices and methods of manufacturing
the meta-surface optical devices will now be described in detail
with reference to the accompanying drawings. In the drawings,
thicknesses of layers and regions may be exaggerated for clarity of
the specification.
[0067] FIG. 1D is a cross-sectional view of a meta-surface optical
device according to an exemplary embodiment.
[0068] Referring to FIG. 1D, a meta-surface 118 is formed on a
region of a substrate 110. The substrate 110 may be a material
layer that is transparent with respect to light. The meta-surface
118 includes a plurality of patterns 120 formed on the substrate
110. The patterns 120 are separated from each other by first gaps
d1. The first gaps d1 by which the patterns 120 are separated may
be constant or may vary. The patterns 120 may have various
respective widths w1. The widths w1 of the patterns 120 may be
equal to each other or may vary. The first gaps d1 between the
patterns 120 and the widths w1 of the patterns 120 may be less than
a wavelength of light incident on the meta-surface 118. A material
layer (hereinafter, a meta-material layer) 112 used for forming the
meta-surface 118 is formed on the substrate 110 on both sides of
the meta-surface 118. The material forming the patterns 120 may be
the same as the material of the meta-material layer 112. The
meta-material layer 112 may be a transparent material layer, and
may include any of various materials according to the light
intended to be incident on the device. The meta-material layer 112
may be formed of any of various dielectric materials, for example,
amorphous silicon a-Si, titanium oxide (for example, TiO.sub.2), or
silicon nitride (for example, Si.sub.3N.sub.4). The meta-material
layer 112 formed on both sides of the meta-surface 118 may
respectively include alignment key patterns 114 and 116. The
alignment key patterns 114 and 116 may be symmetrical with respect
to the meta-surface 118. The alignment key patterns 114 and 116 may
be through holes passing through the meta-material layer 112. Metal
patterns or embossed patterns may also be formed as alignment key
patterns. The metal patterns or the embossed patterns may be formed
along or together with the through holes. Portions of the substrate
110 are thus exposed through the alignment key patterns 114 and
116. The height and type of the alignment key patterns 114 and 116
may be the same as the height and type of alignment key patterns
used in a related art semiconductor photolithography process. A
light absorption layer 130 may be arranged on the meta-material
layer 112. The light absorption layer 130 may cover the
meta-material layer 112 to prevent light from being incident on the
meta-material layer 112. The light absorption layer 130 may fill
the through holes, to be the alignment key patterns 114 and 116,
and may completely cover an upper surface of the meta-material
layer 112 around the alignment key patterns 114 and 116. The light
absorption layer 130 may be, for example, a photo-definable polymer
layer.
[0069] Next, a method of manufacturing a meta-surface optical
device according to an exemplary embodiment will now be described
with reference to FIGS. 1A through 1D.
[0070] Referring to FIG. 1A, the meta-material layer 112 is formed
on the substrate 110. The substrate 110 may be formed of a material
that is transparent with respect to incident light. The
meta-material layer 112 may be formed of the dielectric materials
described above. A first region A1, in which the meta-surface 118
(refer to FIG. 1B) will be formed, and second and third regions AK1
and AK2, in which the alignment key patterns 114 and 116 will be
formed, are defined on the meta-material layer 112. One of the
second and third regions AK1 and AK2 may be on one side of the
first region A1 and the other of the second and third regions AK1
and AK2 may be on the other side of the first region A1. The second
and third regions AK1 and AK2 may be symmetrical with respect to
the first region A1.
[0071] Referring to FIG. 1B, the meta-surface 118 including the
patterns 120 is formed on the first region A1 in the meta-material
layer 112. When the meta-surface 118 is formed, first and second
alignment key patterns 114 and 116 respectively are also formed on
the second and third regions AK1 and AK2 in the meta-material layer
112. The first and second alignment key patterns 114 and 116 may be
formed for aligning a photomask in a subsequent patterning process
of the meta-material layer 112. The meta-surface 118 and the first
and second alignment key patterns 114 and 116 may be formed by
using any of various nano-processes, such as photolithography,
e-beam lithography, nano-imprint, soft-lithography, etc. dry
etching, or deposition or a composite of these processes. The
patterns 120 included in the meta-surface 118 may be formed to be
separated from each other by the first gaps d1. The first gaps d1
between the patterns 120 may be constant, as shown, or may vary.
Each of the patterns 120 may have provided widths w1. The widths w1
of the patterns 120 may be equal to each other, as shown, or may
vary. The patterns 120 may have a provided height h1. The height h1
of the patterns 120 may be equal to each other, as shown, or may
vary.
[0072] Next, as depicted in FIG. 1C, the light absorption layer 130
completely covering the meta-material layer 112 and the
meta-surface 118 is formed on the substrate 110 and on the
remaining portions of the meta-material. Thus, the light absorption
layer 130 may also completely cover the first and second alignment
key patterns 114 and 116. The surface of the light absorption layer
130 may be flat. Next, after a photomask M1 is formed on the light
absorption layer 130 outside a region of the meta-surface 118, the
light absorption layer 130 is removed from the meta-surface 118. As
an example, after selectively exposing a region of the light
absorption layer 130 corresponding to the meta-surface 118 by using
a general selective photolithography process, only the light
absorption layer 130 in the region of the meta-surface 118 may be
removed by developing the exposed region of the light absorption
layer 130. In this manner, as depicted in FIG. 1D, the meta-surface
optical device is formed.
[0073] Since the light absorption layer 130 is formed on both sides
of the meta-surface 118, light, for example, zero-order light
incident on the regions outside the meta-surface 118 may be
absorbed by the light absorption layer 130. Accordingly, a defect,
for example, an image of the meta-surface 118 or a bright spot on a
boundary of the meta-surface 118 due to zero-order light does not
occur on an image region formed by light incident on through the
meta-surface 118.
[0074] As a result, due to the light absorption layer 130 provided
around the meta-surface 118, the quality of an image region, for
example, a structured optical pattern formed by the meta-surface
118 may be increased. The light absorption layer 130 is only one
example of a light control member, and as described below, there
are various types of light control members.
[0075] Next, a meta-surface optical device according to another
exemplary embodiment will now be described. In this case, a light
control member is arranged on a rear side of a substrate.
[0076] Referring to FIG. 2C, the meta-surface 118 and the alignment
key patterns 114 and 116 are arranged on the substrate 110. The
arrangement of the meta-surface 118 and the alignment key patterns
114 and 116 may be the same as that of FIG. 1D. A cladding layer
210 is formed on the substrate 110 and over the meta-surface 118
and the alignment key patterns 114 and 116. The cladding layer 210
fills through holes that are the alignment key patterns 114 and
116. The cladding layer 210 covers the meta-material layer 112 and
the meta-surface 118. The cladding layer 210 may be a planarization
layer. The cladding layer 210 may be, for example, a spin-on-glass
(SOG) layer, an SiO2 layer or an Si3N4 layer and so on. A light
absorption layer 220 is attached to a bottom surface of the
substrate 110. The light absorption layer 220 may be the same
material as the light absorption layer 130 of FIG. 1D. The light
absorption layer 220 is arranged below the meta-material layer 112
and is not arranged below the meta-surface 118. Accordingly, light
incident on the meta-material layer 112 outside a region of the
meta-surface 118 is absorbed by the light absorption layer 220.
[0077] Next, a method of manufacturing the meta-surface optical
device according to another exemplary embodiment will now be
described with reference to FIGS. 2A through 2C.
[0078] Referring to FIG. 2A, the meta-surface 118 and the alignment
key patterns 114 and 116 are formed on the substrate 110. The
meta-surface 118 and the alignment key patterns 114 and 116 may be
formed as the method described with reference to FIGS. 1A and 1B.
Next, the cladding layer 210 covering the meta-surface 118, the
alignment key patterns 114 and 116, and the meta-material layer 112
is formed on the substrate 110 and over the meta-surface 118 and
the alignment key patterns 114 and 116. The cladding layer 210 may
be, for example, an SOG layer. After forming the cladding layer
210, a surface of the cladding layer 210 is flattened.
[0079] Next, as depicted in FIG. 2B, the light absorption layer
220, completely covering a bottom surface of the substrate 110, is
formed. The light absorption layer 220 may be a photo-definable
polymer layer. Next, the light absorption layer 220 below the
meta-surface 118 is removed by patterning the light absorption
layer 220. The patterning of the light absorption layer 220 may be
performed by using any of various nano-processes, such as
photolithography, e-beam lithography, nano-imprint,
soft-lithography, etc. dry etching, or deposition or a composite of
these processes.
[0080] In this way, as depicted in FIG. 2C, the meta-surface
optical device may be formed, in which the portions of the bottom
surface of the substrate 110 adjacent to the portion opposite the
meta-surface 118 are covered by the light absorption layer 220.
[0081] FIG. 3A is a plan view of a meta-surface optical device
according to another exemplary embodiment.
[0082] Referring to FIG. 3A, the meta-surface optical device
includes a first region 300A in which a meta-surface is formed and
a second region 300B surrounding the first region 300A. The second
region 300B performs an operation different from that of the first
region 300A with respect to incident light. The first region 300A
includes a plurality of patterns 310 that perform a specific
operation with respect to incident light. For example, the specific
operation may be an operation of refracting or diffracting the
incident light. Also, the second region 300B includes a plurality
of patterns 320. The patterns 320 in the second region 300B may be
light control members that effect the progress of light or change
the progress direction of light, and perform an operation different
from the operation of the patterns 310 formed in the first region
300A with respect to incident light. The patterns 310 in the first
region 300A constitute a meta-surface. The patterns 310 are
separated from each other by second gaps d2. The second gaps d2 may
have a size less than a wavelength of light incident onto the first
region 300A. The patterns 320 in the second region 300B are
separated from each other by third gaps d3. The third gaps d3 may
be larger or smaller than the second gaps d2. The patterns 320 in
the second region 300B may be provided to cause an operation, for
example, absorption, reflection, or high refraction, different from
that of the meta-surface with respect to incident light. Here, the
phrase "high refraction" denotes a refraction of light incident
onto the second region 300B so that the light incident on the
second region 300B deviates from an image region formed by the
meta-surface in the first region 300A. One of the absorption,
reflection, and high refraction may be referred to as a first
operation with respect to incident light, while another of the
absorption, reflection, and high refraction may be a second
operation, and yet another of the absorption, reflection, and high
refraction may be a third operation.
[0083] FIG. 3B is a cross-sectional view taken along a line 3B-3B'
of FIG. 3A.
[0084] Referring to FIG. 3B, patterns, that is, meta-surface
patterns 310, are formed in a first region 300A of a transparent
substrate 300 and a plurality of patterns 320 are formed in a
second region 300B of a transparent substrate 300. Third gaps d3
and widths w3 of the patterns 320 in the second region 300B may be
greater or less than second gaps d2 and widths w2 of the patterns
310 in the first region 300A. A height h2 of the patterns 310 in
the first region 300A may be equal to that of the patterns 320 in
the second region 300B.
[0085] According to another exemplary embodiment, as depicted in
FIG. 3C, patterns 310 may be arranged in the first region 300A of
FIG. 3C, and patterns 330, having gaps d2 and widths w2 of the
first patterns 310 of FIG. 3B, may be arranged in the second region
300B of FIG. 3C. However, as shown in FIG. 3C, the heights of the
meta-surface patterns 310 in the first region 300A and of the
patterns 320 in the second region 300B may be different from each
other. For example, a height h11 of the meta-surface patterns 310
in the first region 300A may be less than a height h2 of the
patterns 330 in the second region 300B. FIG. 3D shows a case
opposite to the case of FIG. 3C. That is, the meta-surface patterns
310 in the first region 300A have a height greater than that of the
patterns 320 in the second region 300B.
[0086] The results of FIG. 3C or FIG. 3D may be obtained by forming
patterns 370 having the same height over a whole surface of the
transparent substrate 300, as shown in FIG. 3E, and by subsequently
selectively etching the patterns 370 in an unselected region in a
state in which a selected region, for example, the first region
300A, is protected by a mask M2. Accordingly, the height of the
patterns 370 in the unselected region may be controlled by
controlling an etching time.
[0087] Alternately, the meta-surface patterns 310 having different
heights from each other may be formed by selectively etching a
meta-surface material layer after forming the meta-surface material
layer on the transparent substrate 300; or, the meta-surface
patterns 310 having different heights may be formed by processing
meta-surface material layers having different heights through any
of various processes, as would be understood by one of skill in the
art.
[0088] As depicted in FIG. 4A, the patterns 320, similar to those
of FIG. 3B, may be arranged in the second region 300B on a bottom
surface of the transparent substrate 300. As depicted in FIG. 4B,
the patterns 330, similar to those of FIG. 3C, may be arranged in
the second region 300B, on the bottom surface of the transparent
substrate 300. As depicted in FIG. 4C, the patterns 330, similar to
those of FIG. 3D, may be arranged in the second region 300B on the
bottom surface of the transparent substrate 300.
[0089] FIGS. 5 through 13 are cross-sectional views respectively
showing operations of meta-surfaces and light control members
formed around the meta-surfaces with respect to incident light. The
meta-surfaces may be the meta-surface patterns 310 formed in the
first region 300A as described with respect to any of reference to
FIGS. 3 and 4, and the light control members may be the patterns
320 formed in the second region 300B, as described with respect to
any of FIGS. 3 and 4.
[0090] In FIGS. 5 through 13, for convenience, the meta-surfaces
including a plurality of patterns formed on the transparent
substrate 300 are depicted as a single material layer, and also,
the light control members are depicted as a single material
layer.
[0091] FIG. 5 shows a case in which both a meta-surface 520 and a
light control member 530 are arranged on a surface of a substrate
510 facing a light source 500, and the light control member 530
includes patterns configured to reflect incident light.
[0092] Referring to FIG. 5, of light emitted from the light source
500, light (illustrated with solid lines) that is sequentially
transmitted through the meta-surface 520 and the substrate 510
forms an image 540 in a region separated from the substrate 510.
The image 540 may be a structured optical pattern. Of the light
emitted from the light source 500, light (illustrated with dashed
lines) incident on the light control member 530 around the
meta-surface 520 is reflected by the light control member 530.
[0093] FIG. 6 shows a case in which both of a meta-surface 520 and
a light control member 550 are arranged on a surface of a substrate
510 facing a light source 500, and the light control member 550
includes a plurality of patterns configured to absorb incident
light.
[0094] Referring to FIG. 6, of light emitted from the light source
500, light (illustrated with solid lines) that is sequentially
transmitted through the meta-surface 520 and the substrate 510
forms an image 540 in a region separated from the substrate 510. Of
the light emitted from the light source 500, light (illustrated
with dashed lines) incident on the light control member 550 around
the meta-surface 520 is absorbed by the light control member
550.
[0095] FIG. 7 shows a case in which both of a meta-surface 520 and
a light control member 560 are arranged on a surface of a substrate
510 facing a light source 500, and the light control member 560
includes a plurality of patterns configured to refract incident
light away from a region in which an image 540 is formed.
[0096] Referring to FIG. 7, the operation of the meta-surface 520
is the same as that of the meta-surface 520 of FIG. 5. Of light
emitted from the light source 500, light (illustrated with dashed
lines) incident on the light control member 560 around the
meta-surface 520 is refracted away from the region in which the
image 540 is formed by the light transmitted by meta-surface
520.
[0097] FIG. 8 shows a case in which both a meta-surface 520 and
first and second light control members 530 and 550 different from
each other are arranged on a surface of the substrate 510 facing
the light source 500. According to this exemplary embodiment, the
first and second light control members 530 and 550 include patterns
configured to perform operations different from those of the meta
surface 520 with respect to incident light.
[0098] Referring to FIG. 8, the operation of the meta-surface 520
is the same as that of the meta-surface 520 of FIG. 5. Of light
emitted from the light source 500, light (illustrated with dashed
lines) incident on the first light control member 530 around the
meta-surface 520 is reflected and light (also illustrated with
dashed lines) incident on the second light control member 550 is
absorbed by the second light control member 550.
[0099] FIG. 9 shows a case in which a meta-surface 520 and a light
control member 530 respectively are arranged on opposite surfaces
of a substrate 510, and the light control member 530 includes
patterns configured to reflect incident light.
[0100] Referring to FIG. 9, the meta-surface 520 is arranged on a
surface (hereinafter, a first surface) of the substrate 510 facing
the light source 500. The light control member 530 is arranged on a
surface (hereinafter, a second surface) of the substrate 510
opposite the first surface.
[0101] Of light emitted from the light source 500, light
(illustrated with solid lines) that is sequentially transmitted
through the meta-surface 520 and the substrate 510 forms an image
540 in a region separated from the substrate 510. Of the light
emitted from the light source 500, light (illustrated with dashed
lines) incident on the light control member 530 around the
meta-surface 520 is reflected by the light control member 530, back
towards the light source 500 after being transmitted through the
substrate 510.
[0102] FIG. 10 shows a case in which a meta-surface 520 and a light
control member 550 are arranged on different surfaces of the
substrate 510, and the light control member 550 includes patterns
configured to absorb incident light.
[0103] Referring to FIG. 10, the meta-surface 520 is arranged on
the first surface of the substrate 510 and the light control member
550 is arranged on the second surface of the substrate 510. The
arrangement location of the light control member 550 is the same as
that shown in FIG. 9.
[0104] Of light emitted from the light source 500, the operation of
light (illustrated with solid lines) that has passed through the
meta-surface 520 is the same as the operation of the light incident
on the meta-surface 520 of FIG. 9. Of the light emitted from the
light source 500, light (illustrated with dashed lines) incident on
the light control member 550 is absorbed by the light control
member 550 after being transmitted through the substrate 510.
[0105] FIG. 11 shows a case in which a meta-surface 520 and a light
control member 560 respectively are arranged on different surfaces
of the substrate 510, and the light control member 560 includes
patterns configured to refract incident light away from the region
in which the image 540 is formed.
[0106] Referring to FIG. 11, the meta-surface 520 is arranged on
the first surface of the substrate 510. The light control member
560 is arranged on the second surface of the substrate 510. The
arrangement location of the light control member 560 may be the
same as that shown in FIG. 9.
[0107] Of light emitted from the light source 500, an operation of
light (illustrated with solid lines) that has been transmitted
through the meta-surface 520 is the same as the operation of the
light transmitted through the meta-surface 520 of FIG. 9. Of the
light emitted from the light source 500, light (illustrated with
dashed lines) incident on the light control member 560, after being
transmitted through the substrate 510, is refracted away from the
image 540.
[0108] FIG. 12 shows a case in which a meta-surface 520 is arranged
on the first surface of the substrate 510 and first and second
light control members 530 and 560, which perform operations
different from each other with respect to incident light, are
arranged on the second surface of the substrate 510, and the first
and second light control members 530 and 560 include patterns
configured to respectively reflect light and to refract light away
from the image 540.
[0109] Referring to FIG. 12, the locations of arrangements of the
light control members 530 and 560 may be the same as the locations
of the light control members 530, 550, and 560 as shown in FIGS. 9
through 11.
[0110] The operation of light (illustrated with solid lines) that
is transmitted through the meta-surface 520 is the same as the
light incident on the meta-surface 520 of FIG. 9. Of the light
emitted from the light source 500, light (illustrated with dashed
lines) incident on the light control member 530 is reflected
therefrom after being transmitted through the substrate 510. Of
light emitted from the light source 500, light (also illustrated
with dashed lines) incident on the light control member 560 is
refracted away from the image 540.
[0111] FIG. 13 shows a case in which a meta-surface 520 is arranged
on the first surface of the substrate 510 and light control members
530 and 550, that perform operations different from each other with
respect to incident light are arranged on the second surface of the
substrate 510, and the light control members 530 and 550 include
patterns configured to respectively reflect and absorb incident
light.
[0112] Referring to FIG. 13, arrangement locations of the light
control members 530 and 550 are the same as the locations of the
light control members 530 and 560 of FIG. 12.
[0113] An operation of the light (illustrated with solid lines)
that has been transmitted through the meta-surface 520 is the same
as the light incident on the meta-surface 520 of FIG. 9. Of light
emitted from the light source 500, light (illustrated with dashed
lines) incident on the light control member 530 is reflected after
being transmitted through the substrate 510. Of the light emitted
from the light source 500, light (also illustrated with dashed
lines) incident on the light control member 550 is absorbed by the
light control member 550.
[0114] FIG. 14 is a cross-sectional view of a meta-surface optical
device according to another exemplary embodiment.
[0115] Like reference numerals are used to indicate elements that
are identical to the elements described above.
[0116] Referring to FIG. 14, the meta-surface patterns 120, the
meta-material layer 112, and the alignment key patterns 114 and 116
that are described with reference to FIG. 1B are arranged on the
substrate 110. The meta-material layer 112, disposed around the
meta-surface 118, and the alignment key patterns 114 and 116 are
covered by a metal film 1410. The through holes, that is, the
alignment key patterns 114 and 116 are also covered by the metal
film 1410. That is, all regions on the substrate 110 except for the
region of the meta-surface 118 are covered by the metal film 1410.
The metal film 1410 may be a light control member that reflects
incident light. Accordingly, all light incident on regions around
the meta-surface 118 may be reflected by the metal film 1410. The
metal film 1410 may be, for example, an Au film.
[0117] FIGS. 15A through 15D are cross-sectional views of a method
of manufacturing the meta-surface optical device of FIG. 14.
[0118] Referring to FIG. 15A, as described with reference to FIG.
1B, the meta-surface 118 and the alignment key patterns 114 and 116
are formed in the meta-material layer 112 on the substrate 110.
Next, a mask layer 1500 covering the meta-material layer 112, the
meta-surface 118, the alignment key patterns 114 and 116, and
exposed portions of the substrate 110 is formed on the substrate
110. The mask layer 1500 may be a photosensitive film. As shown in
FIG. 15B, after exposing a portion of the mask layer 1500 by using
a photolithography process, the mask layer 1500 is removed except
for the portion covering the meta-surface 118.
[0119] Next, as depicted in FIG. 15C, the metal film 1410 is formed
to cover completely the upper surface of the mask layer 1500, the
meta-material layer 112, the alignment key patterns 114 and 116,
and exposed regions of the substrate 110. Accordingly, all regions
around the mask layer 1500 including the upper surface of the
remaining portion of the mask layer 1500 are covered by the metal
film 1410. Afterwards, the mask layer 1500 is removed by using a
lift-off process. At this point, the metal film 1410 formed on the
mask layer 1500 is also removed. The mask layer 1500 may be removed
by using, for example, an ashing process.
[0120] In this way, as depicted in FIG. 15D, a meta-surface optical
device in which the metal film 1410 as a light control member is
formed around the meta-surface 118 is formed.
[0121] FIG. 16 is a cross-sectional view of a meta-surface optical
device according to another exemplary embodiment.
[0122] FIG. 16 shows a case in which meta-surfaces are respectively
formed on both surfaces of a transparent substrate 1700.
[0123] Referring to FIG. 16, a first meta-material layer 1710 is
arranged on an upper surface of the substrate 1700. The first
meta-material layer 1710 includes a first meta-surface 1718 and
first alignment key patterns 1714. The first meta-surface 1718
includes a plurality of patterns 1720. The substrate 1700 is
exposed through gaps between the patterns 1720. The patterns 1720
are separated by first gaps d1. Each of the patterns 1720 has a
width w1 and a height h1. The first gaps d1 and the width w1 are
less than a wavelength of incident light. A first cladding layer
1730 is formed to cover the first meta-surface 1718, the first
alignment key patterns 1714, and exposed portions of the substrate
1700. A surface of the first cladding layer 1730 is flat. The first
cladding layer 1730 may be, for example, a spin-on-glass (SOG)
layer. A first light blocking layer 1750 is arranged on the first
cladding layer 1730. The first light blocking layer 1750 may
completely cover an upper surface of the first cladding layer 1730
except for a portion of the first cladding layer 1730 corresponding
to the first meta-surface 1718. The first light blocking layer 1750
may be a light absorption layer or a light reflection layer. The
first light blocking layer 1750 may be a metal layer or a polymer
layer.
[0124] A second meta-material layer 1712 is attached to a bottom
surface of the transparent substrate 1700. The second meta-material
layer 1712 includes a second meta-surface 1738 and second alignment
key patterns 1734. The second alignment key patterns 1734 are
formed by one and one on both sides of the second meta-surface
1738. The second alignment key patterns 1734 may be vertically
symmetrical, about the transparent substrate 1700, with respect to
the first alignment key patterns 1714. The first meta-surface 1738
includes a plurality of patterns 1760. The patterns 1760 are
separated by fourth gaps d4, and each has a width w4. The fourth
gaps d4 and the width w4 of the patterns 1760 that constitute the
second meta-surface 1738 are less than a wavelength of incident
light. The fourth gaps d4 and the width w4 of the patterns 1760
that constitute the second meta-surface 1738 may be different from
the first gaps d1 and the width w1 of the patterns 1720 that
constitute the first meta-surface 1718. The fourth gaps d4 and the
width w4 of the patterns 1760 that respectively constitute the
second meta-surface 1738 may be greater than the first gaps d1 and
the width w1 of the patterns 1720 that constitute the first
meta-surface 1718. The first meta-surface 1718 and the second
meta-surface 1738 may be operated, respectively, as different
optical elements from each other with respect to incident light.
For example, the first meta-surface 1718 may act as a first
refractive optical element and the second meta-surface 1738 may act
as a second refractive optical element. For example, the first and
second refractive optical elements may be a lens.
[0125] Next, a second cladding layer 1770 is formed, covering the
second meta-surface 1738 and the second alignment key patterns
1734, below the second meta-material layer 1712. The second
cladding layer 1770 may include the same material as the first
cladding layer 1730. A bottom surface of the second cladding layer
1770 is flat. A second light blocking layer 1790 is attached to the
bottom surface of the second cladding layer 1770. The second light
blocking layer 1790 covers the whole bottom surface of the second
cladding layer 1770 except for a portion of the second cladding
layer 1770 corresponding to the second meta-surface 1738. The
second light blocking layer 1790 may be a light absorption layer or
a light reflection layer.
[0126] FIGS. 17A through 17I are cross-sectional views of a method
of manufacturing the meta-surface optical device of FIG. 16.
[0127] Referring to FIG. 17A, the first meta-material layer 1710 is
formed on an upper surface of the transparent substrate 1700. The
first meta-material layer 1710 may include any of various
dielectric materials, for example, amorphous silicon a-Si, titanium
oxide (for example, TiO.sub.2), or silicon nitride (for example,
Si.sub.3N.sub.4). The first meta-material layer 1710 may include a
first region 17A1, on which a meta-surface will be formed in a
subsequent process, and second and third regions 17A2 and 17A3, on
which alignment key patterns 114 and 116 will be formed in a
subsequent process. The second meta-material layer 1712 is formed
on the bottom surface of the transparent substrate 1700.
[0128] As depicted in FIG. 17B, the first meta-surface 1718 and the
first alignment key patterns 1714 are formed by patterning the
first meta-material layer 1710 using, for example, the method
described with reference to FIG. 1B.
[0129] As depicted in FIG. 17C, the first cladding layer 1730 is
formed, completely covering the first meta-surface 1718, the first
alignment key patterns 1714, and exposed regions of the upper
surface of the transparent substrate 1700, and the upper surface of
the first cladding layer 1730 is planarized. Accordingly, the first
meta-surface 1718, the first alignment key patterns 1714, and
exposed portions of the transparent substrate 1700 are covered by
the first cladding layer 1730. The first cladding layer 1730 may be
an SOG layer, but is not limited thereto.
[0130] As depicted in FIG. 17D, a mask 1740, that covers a portion
of the first cladding layer 1730 corresponding to the first
meta-surface 1718 and exposes remaining portions of the first
cladding layer 1730, is formed on the first cladding layer 1730.
The mask 1740 may be a photo-sensitive film.
[0131] As depicted in FIG. 17E, the first light blocking layer 1750
is formed, covering the mask 1740 and exposed portions of the first
cladding layer 1730. The first light blocking layer 1750 may be a
light absorption layer or a light reflection layer. The first light
blocking layer 1750 may be, for example, a metal layer or a polymer
layer, but is not limited thereto. When the mask 1740 is removed by
using a lift process, the portion of the first light blocking layer
1750 formed on the mask 1740 is also removed together with the mask
1740. As depicted in FIG. 17F, the first light blocking layer 1750
corresponding to the first meta-surface 1718 is removed, and only
the first light blocking layer 1750 corresponding to peripheral
regions of the first meta-surface 1718 remains.
[0132] As depicted in FIG. 17G, the product of FIG. 17F may be
turned over, such that the second meta-material layer 1712 is
disposed placed above the transparent substrate 1700. As described,
for example, with reference to FIG. 1B, the second meta-surface
1738 and the second alignment key patterns 1734, separated from the
second meta-surface 1738 in the second meta-material layer 1712,
are formed by patterning the second meta-material layer 1712. The
second meta-surface 1738 is formed on a location corresponding to
the location of the first meta-surface 1718, and the second
alignment key patterns 1734 may be formed on locations
corresponding to the locations of the first alignment key patterns
1714. The second cladding layer 1770 is formed on the second
meta-surface 1738, the second alignment key patterns 1734, and
exposed portions of the transparent substrate 1700. Accordingly,
all of the second meta-material layer 1712, the second meta-surface
1738, the second alignment key patterns 1734, and exposed portions
of the transparent substrate 1700 are covered by the second
cladding layer 1770.
[0133] As depicted in FIG. 17H, a mask 1780 is formed only on a
region of the second cladding layer 1770 corresponding to the
second meta-surface 1738. The mask 1780 may be a photo-sensitive
film. The second light blocking layer 1790 is formed, covering an
upper surface of the mask 1780 and exposed regions of the second
cladding layer 1770. The second light blocking layer 1790 may be a
light absorption layer or a light reflection layer. The second
light blocking layer 1790 may be made of the same material as the
first light blocking layer 1750. After the second light blocking
layer 1790 is formed, the mask 1780 is removed by using a lift-off
process. The second light blocking layer 1790 formed on the mask
1780 is also removed together with the mask 1780.
[0134] As a result, as depicted in FIG. 17I, a meta-surface optical
device, having the second meta-surface 1738 and the first
meta-surface 1718 respectively on and below the transparent
substrate 1700 and that blocks light incident on peripheral regions
of the second meta-surface 1738 and the first meta-surface 1718,
may be formed.
[0135] FIG. 18 is a cross-sectional view of a meta-surface optical
device according to another exemplary embodiment.
[0136] A plurality of meta-surfaces are formed on a transparent
substrate 1700.
[0137] Referring to FIG. 18, a first meta-material layer 1710
including a first meta-surface 1718 and first alignment key
patterns 1714 is formed on the transparent substrate 1700. The
first meta-material layer 1710 is covered by a first cladding layer
1730, and a surface of the first cladding layer 1730 is flat. A
second meta-material layer 1810 that includes a second meta-surface
1818 and second alignment key patterns 1814 is formed on the first
cladding layer 1730. The second meta-surface 1818 may be made of
the same material as the first meta-material layer 1710. The second
meta-surface 1818 includes a plurality of patterns 1820. The
patterns 1820 may have gaps, widths, and heights corresponding to
the gaps d1, width w1, and height h1 of the patterns 1720 of the
first meta-surface 1718. The second meta-material layer 1810 is
covered by a second cladding layer 1830, and a surface of the
second cladding layer 1830 is flat. A light blocking layer 1850 is
arranged on the second cladding layer 1830. The light blocking
layer 1850 is arranged on the third cladding layer 1830 except for
a region of the second cladding layer 1830 corresponding to the
second meta-surface 1818. The light blocking layer 1850 may be one
of the light control members that change a progress of light or a
direction of progress of light, and may be a light absorption layer
or a light reflection layer. Also, the light blocking layer 1850
may be a metal layer or a polymer layer, but is not limited
thereto.
[0138] FIGS. 19A through 19E are cross-sectional views of a method
of manufacturing the meta-surface optical device of FIG. 18.
[0139] Referring to FIG. 19A, after forming the first meta-material
layer 1710 on the transparent substrate 1700, the first
meta-surface 1718 and the first alignment key patterns 1714 are
formed by patterning the first meta-material layer 1710. The first
meta-surface 1718 and the first alignment key patterns 1714 may be
formed, for example, by using a method described with reference to
FIG. 1B. The first cladding layer 1730 covering the first
meta-material layer 1710 is formed, and afterwards, an upper
surface of the first cladding layer 1730 is planarized. The second
meta-material layer 1810 is formed on the first cladding layer
1730. The second meta-material layer 1810 may include the same
material as the first meta-material layer 1710.
[0140] Next, as depicted in FIG. 19B, the second meta-surface 1818
and the second alignment key patterns 1814 are formed in the second
meta-material layer 1810 by patterning the second meta-material
layer 1810. Accordingly, the second meta-surface 1818 and the
second alignment key patterns 1814 are formed on the first cladding
layer 1730. The second meta-surface 1818 and the second alignment
key patterns 1814 may be formed, for example, by using a method
described with reference to FIG. 1B. The second meta-surface 1818
may be formed on a location corresponding to the location of the
first meta-surface 1718, and the second alignment key patterns 1814
may be formed on locations corresponding to the locations of the
first alignment key patterns 1714.
[0141] As depicted in FIG. 19C, the second cladding layer 1830 is
formed, covering the second meta-surface 1818, the second
meta-surface 1818, the second alignment key patterns 1814, and
exposed portions of the first cladding layer 1730. Accordingly, all
of the second meta-surface 1818, the second alignment key patterns
1814, and exposed portions of the first cladding layer 1730 are
covered by the second cladding layer 1830. The second cladding
layer 1830 may include the same material as the first cladding
layer 1730.
[0142] As depicted in FIG. 19D, the light blocking layer 1850 is
formed on the second cladding layer 1830. The light blocking layer
1850 is formed only on a region of the second cladding layer 1830.
The light blocking layer 1850 may be formed on a whole upper
surface of the second cladding layer 1830 except for a region of
the second cladding layer 1830 corresponding to the second
meta-surface 1818. The light blocking layer 1850 may be a light
absorption layer or a light reflection layer. The light blocking
layer 1850 may be, for example, a metal layer or a polymer layer,
but is not limited thereto.
[0143] In this way, the meta-surface optical device depicted in
FIG. 18 may be formed.
[0144] Alternatively, before forming the light blocking layer 1850
in FIG. 19D, as depicted in FIG. 19E, a process of stacking the
second meta-material layer 1810 and the second cladding layer 1830
on the second cladding layer 1830 may further be performed at least
one times. At this point, the light blocking layer 1850 may be
formed on the uppermost cladding layer.
[0145] FIGS. 20A through 20C are cross-sectional views of a
meta-surface optical device according to another exemplary
embodiment.
[0146] Referring to FIG. 20A, a separated meta-material layer 2012
is formed on a transparent substrate 2010. The meta-material layer
2012 may include any of various dielectric materials, for example,
amorphous silicon a-Si, titanium oxide (for example, TiO.sub.2), or
silicon nitride (for example, Si.sub.3N.sub.4). A meta-surface 2060
is formed between the separated meta-material layers 2012. The
meta-surface 2060 includes a plurality of patterns 2040. The
patterns 2040 are separated from each other by fifth gaps d5, and
have a width w5 and a height h5. The fifth gaps d5 and the width w5
are less than a wavelength of incident light. The patterns 2040 may
include the same material as the meta-material layer 2012. A light
blocking film 2020 is provided on the meta-material layer 2012. The
light blocking film 2020 covers a whole upper surface of the
meta-material layer 2012. The light blocking film 2020 may be a
light reflection layer or a light absorption layer. The light
blocking film 2020 may be, for example, a metal layer or a polymer
layer, but is not limited thereto.
[0147] As depicted in FIG. 20B, the light blocking film 2020 of
FIG. 20A may be arranged on a bottom surface of the transparent
substrate 2010. Also, as depicted in FIG. 20C, the light blocking
film 2020 may be arranged between the transparent substrate 2010
and the meta-material layer 2012.
[0148] FIGS. 21A through 21G are cross-sectional views of a method
of manufacturing the meta-surface optical device of FIG. 20A.
[0149] Referring to FIG. 21A, the meta-material layer 2012 and the
light blocking layer 2020 are sequentially stacked on the
transparent substrate 2010.
[0150] As depicted in FIG. 21B, a mask layer 2030 is formed on the
light blocking layer 2020. The mask layer 2030 may be a
photo-sensitive film layer. The mask layer 2030 includes a pattern
region 2030A including a plurality of patterns 2040A. The patterns
2040A are separated from each other, and thus, the light blocking
layer 2020 is exposed through gaps between the patterns 2040A. The
pattern region 2030A defines a region in which a meta-surface will
be formed. Exposed portions of the light blocking layer 2020 are
etched in a state in which the mask layer 2030 is present. The
etching is continued until the meta-material layer 2012 is
exposed.
[0151] As a result of the etching, as depicted in FIG. 21C, the
whole pattern region 2030A of the mask layer 2030 is transferred to
the light blocking layer 2020. When the mask layer 2030 is removed,
as depicted in FIG. 21D, a pattern region 2020A, formed by
transferring the pattern region 2030A of the mask layer 2030, is
formed in the light blocking layer 2020 on the meta-material layer
2012. The light blocking layer 2020 is used as a mask in a
subsequent process. That is, as depicted in FIG. 21E, the
meta-material layer 2012 is etched by using the light blocking
layer 2020 including the pattern region 2020A. The etching may be
continued until the transparent substrate 2010 is exposed. As a
result of the etching, a meta-surface including a plurality of
patterns 2040 is formed in the meta-material layer 2012.
[0152] As depicted in FIGS. 21F and 21G, the pattern region 2020A
is removed from the light blocking layer 2020 by using a stamp
2050. The stamp 2050 may include any of various polymers including
polydimethylsiloxane (PDMS).
[0153] In this way, the meta-surface optical device depicted in
FIG. 20A is formed. The meta-surface optical devices of FIGS. 20B
and 20C may be readily formed by changing the locations of the
light blocking layer in the process of forming the meta-surface
optical element depicted in FIG. 20A.
[0154] Also, as depicted in FIG. 22, when a material layer 2200
having a high adhesiveness with respect to the light blocking layer
2020 is attached to a surface of the stamp 2050 that is attached to
the pattern region 2020A, the selectivity of the stamp 2050 with
respect to the pattern region 2020A may be increased in the process
of removing the pattern region 2020A using the stamp 2050.
[0155] FIG. 23 is photographs showing an effect of the use of
meta-surface optical devices according to exemplary
embodiments.
[0156] The photograph on the left side shows a case in which a
conventional optical element is used and the photograph on the
right side shows a case in which a meta-surface optical device
according to an exemplary embodiment is used.
[0157] Referring to FIG. 23, in the left photograph, bright
regions, which are defects, are present along a boundary of a
region 23A1 corresponding to a meta-surface. However, in the right
photograph, the defect is not observed.
[0158] Accordingly, this shows that, when a meta-surface optical
device, according to an exemplary embodiments is used, the quality
of an image (for example, a structured optical pattern) formed by
the meta-surface may be increased.
[0159] FIG. 24 shows a case in which a meta-surface region AA1 and
a light control member region AA2 are correctly aligned in a
meta-surface optical device 2300.
[0160] FIG. 25 shows a case in which a gap EA1, having a width D11,
is present between the meta-surface region AA1 and the light
control member region AA2. As depicted in FIG. 28, in order to
obtain a clean structured optical pattern without light-leaking
defect, the size of the gap EA1 may be less than six times a
wavelength of incident light. That is, if the size of the gaps EA1
do not exceed six times of a wavelength of incident light, a
zero-order-effect does not occur.
[0161] For example, if a wavelength of incident light is 940 nm,
and a size of the gap EA1 is within approximately 5 .mu.m, as
depicted in FIG. 28, a clean structured optical pattern without a
zero-order-effect may be obtained.
[0162] FIG. 26 shows a case in which the light control member
region AA2 overlaps the meta-surface region AA1. When the light
control member region AA2 overlaps the meta-surface region AA1 by
as much as a distance D22 from a boundary 2330 therebetween, that
is, when width D22 of the overlap of the light control member
region AA2 with the meta-surface region AA1 is less than ten times
the wavelength of incident light, the zero-order-effect may not
occur. For example, if a wavelength of incident light is 940 nm,
and a width of the overlap is within approximately 9 .mu.m, a clean
structured optical pattern without a zero-order-effect may be
obtained.
[0163] FIGS. 27A, 27B, and 27C are photographs showing actually
measured results with respect to three alignment states of
meta-surfaces and light control members around the
meta-surfaces.
[0164] FIG. 27A, shows a photograph of a state in which the
meta-surface and the light control member are correctly aligned;
FIG. 27B shows a photograph of a state in which a gap having a
width of 2.5 .mu.m is present between the meta-surface and the
light control member; and FIG. 27C shows a photograph of a state in
which a gap having a width of approximately 5 .mu.m is present.
[0165] FIGS. 28A, 28B, and 28C are photographs of structured
optical patterns obtained using meta surface optical devices
aligned as shown in FIGS. 27A, 27B, and 27C, respectively.
[0166] Referring to FIG. 28, when the gaps between the meta-surface
and the light control member are 0 .mu.m, 2.5 .mu.m, and 5 .mu.m,
respectively, the zero-order-effect was not observed.
[0167] While one or more exemplary embodiments have been described
with reference to the figures, it will be understood by those of
ordinary skill in the art that various changes in form and details
may be made therein without departing from the spirit and scope as
defined by the following claims.
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