U.S. patent application number 13/153886 was filed with the patent office on 2011-12-08 for semiconductor light emitting device and method for manufacturing semiconductor light emitting device.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. Invention is credited to Tomomichi NAKA.
Application Number | 20110297985 13/153886 |
Document ID | / |
Family ID | 45063793 |
Filed Date | 2011-12-08 |
United States Patent
Application |
20110297985 |
Kind Code |
A1 |
NAKA; Tomomichi |
December 8, 2011 |
SEMICONDUCTOR LIGHT EMITTING DEVICE AND METHOD FOR MANUFACTURING
SEMICONDUCTOR LIGHT EMITTING DEVICE
Abstract
According to one embodiment, a semiconductor light emitting
device includes a light emitting section, a light transmitting
section, a wavelength conversion section, a first conductive
section, a second conductive section and a sealing section. The
light emitting section includes a first major surface, a second
major surface opposite from the first major surface, and a first
electrode section and a second electrode section formed on the
second major surface. The light transmitting section is provided on
a side of the first major surface. The wavelength conversion
section is provided over the light transmitting section. The
wavelength conversion section is formed from a resin mixed with a
phosphor, and hardness of the cured resin is set to exceed 10 in
Shore D hardness.
Inventors: |
NAKA; Tomomichi;
(Kanagawa-ken, JP) |
Assignee: |
Kabushiki Kaisha Toshiba
Tokyo
JP
|
Family ID: |
45063793 |
Appl. No.: |
13/153886 |
Filed: |
June 6, 2011 |
Current U.S.
Class: |
257/98 ;
257/E33.061; 257/E33.068; 438/27 |
Current CPC
Class: |
H01L 33/62 20130101;
H01L 2933/0041 20130101; H01L 33/508 20130101; H01L 33/502
20130101; H01L 33/54 20130101; H01L 33/44 20130101; H01L 33/501
20130101; H01L 33/507 20130101; H01L 33/52 20130101; H01L 33/505
20130101; H01L 2933/005 20130101; H01L 2224/16 20130101 |
Class at
Publication: |
257/98 ; 438/27;
257/E33.068; 257/E33.061 |
International
Class: |
H01L 33/50 20100101
H01L033/50; H01L 33/44 20100101 H01L033/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 7, 2010 |
JP |
2010-130332 |
Claims
1. A semiconductor light emitting device comprising: a light
emitting section including a first major surface, a second major
surface opposite from the first major surface, and a first
electrode section and a second electrode section formed on the
second major surface; a light transmitting section provided on a
side of the first major surface; a wavelength conversion section
provided over the light transmitting section; a first conductive
section provided on the first electrode section; a second
conductive section provided on the second electrode section; and a
sealing section provided on a side of the second major surface and
sealing the first conductive section and the second conductive
section while exposing an end portion of the first conductive
section and an end portion of the second conductive section, the
wavelength conversion section being formed from a resin mixed with
a phosphor, and hardness of the cured resin being set to exceed 10
in Shore D hardness.
2. The device according to claim 1, wherein refractive index of the
resin is equal to or less than refractive index of the
phosphor.
3. The device according to claim 1, wherein transmittance of the
resin is 90% or more.
4. The device according to claim 1, wherein the wavelength
conversion section includes a shape such that optical path length
in the wavelength conversion section is adjusted to suppress
chromaticity shift in accordance with emission characteristic of
the light emitting section.
5. The device according to claim 4, wherein the light transmitting
section forms the shape of the wavelength conversion section
suppressing the chromaticity shift.
6. The device according to claim 4, wherein the wavelength
conversion section includes a convex shape having a curvature
radius of 250 nm or more.
7. The device according to claim 4, wherein the wavelength
conversion section includes a concave shape having a curvature
radius of 200 nm or more.
8. The device according to claim 1, wherein the resin is at least
one selected from the group consisting of epoxy resin, silicone
resin, methacrylic resin (PMMA), polycarbonate (PC), cyclic
polyolefin (COP), alicyclic acrylate (OZ), allyldiglycol carbonate
(ADC), acrylic resin, fluororesin, a hybrid resin of silicone resin
and epoxy resin, and urethane resin.
9. The device according to claim 1, wherein the resin is at least
one selected from the group consisting of methylphenyl silicone,
dimethyl silicone, and a hybrid resin of methylphenyl silicone and
epoxy resin.
10. The device according to claim 1, wherein the phosphor has an
emission wavelength of 380 nm or more and 720 nm or less, and
includes at least one element selected from the group consisting of
silicon (Si), aluminum (Al), titanium (Ti), germanium (Ge),
phosphorus (P), boron (B), yttrium (Y), alkaline earth element,
sulfide element, rare earth element, and nitride element.
11. A method for manufacturing a semiconductor light emitting
device, the device including: a light emitting section including a
first major surface, a second major surface opposite from the first
major surface, and a first electrode section and a second electrode
section formed on the second major surface; and a wavelength
conversion section provided on a side of the first major surface
and formed from a resin mixed with a phosphor, the method
comprising: setting hardness of the cured resin to exceed 10 in
Shore D hardness.
12. The method according to claim 11, further comprising:
integrally forming the semiconductor light emitting device in a
plurality; and singulating the plurality of integrally formed
semiconductor light emitting devices, in the singulating, the
wavelength conversion section being cut using a blade dicing
method.
13. The method according to claim 11, wherein the hardness of the
cured resin is controlled by adding an additive for increasing
cross-linking sites of the resin.
14. The method according to claim 11, wherein the resin is at least
one selected from the group consisting of epoxy resin, silicone
resin, methacrylic resin (PMMA), polycarbonate (PC), cyclic
polyolefin (COP), alicyclic acrylate (OZ), allyldiglycol carbonate
(ADC), acrylic resin, fluororesin, a hybrid resin of silicone resin
and epoxy resin, and urethane resin.
15. The method according to claim 11, wherein the resin is at least
one selected from the group consisting of methylphenyl silicone,
dimethyl silicone, and a hybrid resin of methylphenyl silicone and
epoxy resin.
16. The method according to claim 11, wherein the phosphor has an
emission wavelength of 380 nm or more and 720 nm or less, and
includes at least one element selected from the group consisting of
silicon (Si), aluminum (Al), titanium (Ti), germanium (Ge),
phosphorus (P), boron (B), yttrium (Y), alkaline earth element,
sulfide element, rare earth element, and nitride element.
17. The method according to claim 11, wherein in forming the
wavelength conversion section, the wavelength conversion section is
formed to include a shape such that optical path length in the
wavelength conversion section is adjusted to suppress chromaticity
shift in accordance with emission characteristic of the light
emitting section.
18. The method according to claim 11, further comprising: forming a
light transmitting section on the side of the first major surface,
in forming the wavelength conversion section, the wavelength
conversion section is formed over the light transmitting
section.
19. The method according to claim 11, wherein in forming the
wavelength conversion section, a convex shape having a curvature
radius of 250 nm or more is formed in the wavelength conversion
section.
20. The method according to claim 11, wherein in forming the
wavelength conversion section, a concave shape having a curvature
radius of 200 nm or more is formed in the wavelength conversion
section.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2010-130332, filed on Jun. 7, 2010; the entire contents of which
are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to a
semiconductor light emitting device and a method for manufacturing
the same.
BACKGROUND
[0003] Semiconductor light emitting devices emitting high
brightness blue light based on Group III nitride semiconductors
such as gallium nitride (GaN) are known. According to already
proposed techniques, a semiconductor light emitting device emitting
blue light can be used to emit white light by combination with a
wavelength conversion section including phosphor having wavelength
conversion capability. Here, productivity can be improved by
integrally forming a plurality of semiconductor light emitting
devices and then singulating each semiconductor light emitting
device. However, in the case where a wavelength conversion section
including phosphor is provided, the phosphor may be detached from
the wavelength conversion section when each semiconductor light
emitting device is singulated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a schematic sectional view illustrating a
semiconductor light emitting device according to an embodiment;
[0005] FIG. 2 is a schematic view for illustrating the emission
characteristic of the light emitting section;
[0006] FIG. 3 is a schematic sectional view illustrating a
semiconductor light emitting device according to a comparative
example;
[0007] FIG. 4 is a schematic graph for illustrating the
chromaticity shift;
[0008] FIGS. 5A to 5D are schematic views for illustrating the
detachment of phosphor; and
[0009] FIG. 6 is a flow chart for illustrating the method for
manufacturing a semiconductor light emitting device according to
the embodiment.
DETAILED DESCRIPTION
[0010] In general, according to one embodiment, a semiconductor
light emitting device includes a light emitting section, a light
transmitting section, a wavelength conversion section, a first
conductive section, a second conductive section and a sealing
section. The light emitting section includes a first major surface,
a second major surface opposite from the first major surface, and a
first electrode section and a second electrode section formed on
the second major surface. The light transmitting section is
provided on a side of the first major surface. The wavelength
conversion section is provided over the light transmitting section.
The first conductive section is provided on the first electrode
section. The second conductive section is provided on the second
electrode section. The sealing section is provided on a side of the
second major surface and seals the first conductive section and the
second conductive section while exposing an end portion of the
first conductive section and an end portion of the second
conductive section. The wavelength conversion section is formed
from a resin mixed with a phosphor, and hardness of the cured resin
is set to exceed 10 in Shore D hardness.
[0011] In general, according to another embodiment, a method is
disclosed for manufacturing a semiconductor light emitting device.
The device includes a light emitting section and a wavelength
conversion section. The light emitting section includes a first
major surface, a second major surface opposite from the first major
surface, and a first electrode section and a second electrode
section formed on the second major surface. The wavelength
conversion section is provided on a side of the first major surface
and formed from a resin mixed with a phosphor. The method includes
setting hardness of the cured resin to exceed 10 in Shore D
hardness.
[0012] Various embodiments will be illustrated hereinafter with
reference to the accompanying drawings. In the figures, similar
components are labeled with like reference numerals, and the
detailed description thereof is omitted as appropriate.
[0013] FIG. 1 is a schematic sectional view illustrating a
semiconductor light emitting device according to an embodiment.
[0014] As shown in FIG. 1, the semiconductor light emitting device
1 includes a light emitting section 2, a light transmitting section
3, a wavelength conversion section 4, a first conductive section 6,
a first connecting member 7, a second conductive section 9, a
second connecting member 10, an insulating section 11, and a
sealing section 12.
[0015] The light emitting section 2 includes a first major surface
M1 and a second major surface M2 opposite from the first major
surface M1. The light emitting section 2 further includes a first
electrode section 5 and a second electrode section 8 formed on the
second major surface M2.
[0016] The light emitting section 2 includes a semiconductor
section 2a, an active section 2b, and a semiconductor section
2c.
[0017] The semiconductor section 2a can be made of a semiconductor
doped into n-type (n-type semiconductor). In this case, the
semiconductor section 2a can be made of an n-type nitride
semiconductor. Examples of the nitride semiconductor can include
GaN (gallium nitride), AlN (aluminum nitride), AlGaN (aluminum
gallium nitride), and InGaN (indium gallium nitride).
[0018] The active section 2b is provided between the semiconductor
section 2a and the semiconductor section 2c.
[0019] The active section 2b can be configured as a quantum well
structure composed of a well layer and a barrier layer (cladding
layer). In the well layer, holes and electrons are recombined to
generate light. The barrier layer has a larger band gap than the
well layer.
[0020] In this case, the quantum well structure may be a single
quantum well (SQW) structure or a multiple quantum well (MQW)
structure. Alternatively, a plurality of single quantum well
structures may be stacked.
[0021] For instance, in an example of the single quantum well
structure, a barrier layer made of GaN (gallium nitride), a well
layer made of InGaN (indium gallium nitride), and a barrier layer
made of GaN (gallium nitride) can be stacked in this order.
[0022] In an example of the multiple quantum well structure, a
barrier layer made of GaN (gallium nitride), a well layer made of
InGaN (indium gallium nitride), a barrier layer made of GaN
(gallium nitride), a well layer made of InGaN (indium gallium
nitride), and a barrier layer made of GaN (gallium nitride) can be
stacked in this order.
[0023] In this case, the aforementioned semiconductor section 2a
can be used as a barrier layer.
[0024] The active section 2b is not limited to quantum well
structures, but can be appropriately selected from structures
capable of emitting light.
[0025] The semiconductor section 2c can be made of a semiconductor
doped into p-type (p-type semiconductor). In this case, the
semiconductor section 2c can be made of a p-type nitride
semiconductor. Examples of the nitride semiconductor can include
GaN (gallium nitride), AlN (aluminum nitride), AlGaN (aluminum
gallium nitride), and InGaN (indium gallium nitride).
[0026] The light emitting section 2 can be e.g. a light emitting
diode having a peak emission wavelength of 380-530 nm.
Alternatively, the light emitting section 2 can be e.g. a light
emitting diode having an emission wavelength band of 350-600
nm.
[0027] The light transmitting section 3 is formed on the first
major surface M1 of the light emitting section 2.
[0028] The light transmitting section 3 transmits light emitted
from the light emitting section 2 and suppresses chromaticity
shift.
[0029] To facilitate transmission of light emitted from the light
emitting section 2, the transmittance of the light transmitting
section 3 can be set to e.g. 90% or more in the wavelength region
of 420-720 nm. The refractive index of the light transmitting
section 3 can be set to 1.2 or more and 1.9 or less.
[0030] The light transmitting section 3 is provided to suppress
chromaticity shift in which the chromaticity varies with the
direction of viewing the semiconductor light emitting device 1.
That is, the light transmitting section 3 is provided so that the
optical path length inside the wavelength conversion section 4 is
adjusted to suppress chromaticity shift in accordance with the
emission characteristic of the light emitting section 2. The
suppression of chromaticity shift will be described later in
detail.
[0031] Examples of the material forming the light transmitting
section 3 can include epoxy resin, silicone resin, methacrylic
resin (PMMA), polycarbonate (PC), cyclic polyolefin (COP),
alicyclic acrylate (OZ), allyldiglycol carbonate (ADC), acrylic
resin, fluororesin, hybrid resin of silicone resin and epoxy resin,
urethane resin, SiO.sub.2, and TiO.sub.2.
[0032] Here, in the case where light emitted from the light
emitting section 2 has a short wavelength from ultraviolet to blue
and high brightness, the material forming the light transmitting
section 3 may be degraded. Thus, the material forming the light
transmitting section 3 is preferably made less prone to degradation
by blue light. Examples of resins less prone to degradation by blue
light can include methylphenyl silicone and dimethyl silicone
having a refractive index of approximately 1.5.
[0033] However, the material is not limited to those illustrated
above, but can be appropriately modified. Here, the diameter
dimension of the opening portion of the concave surface 3a provided
in the light transmitting section 3 (so to speak, the dimension of
the wavelength conversion section 4) is preferably made larger than
the dimension of the light emitting section 2.
[0034] The wavelength conversion section 4 is provided on the first
major surface M1 side of the light emitting section 2 and includes
phosphor described later. The wavelength conversion section 4 is
provided over the light transmitting section 3.
[0035] The wavelength conversion section 4 can be formed from a
resin mixed with phosphor having wavelength conversion
capability.
[0036] The phosphor can be e.g. particulate, with a particle
diameter of 10 .mu.m or less.
[0037] The wavelength conversion section 4 can include at least one
or more of phosphors having a peak emission wavelength of 440 nm or
more and 470 nm or less (blue), 500 nm or more and 555 nm or less
(green), 560 nm or more and 580 nm or less (yellow), and 600 nm or
more and 670 nm or less (red). Furthermore, the wavelength
conversion section 4 can include a phosphor having an emission
wavelength band of 380-720 nm.
[0038] The phosphor can include at least one element selected from
the group consisting of silicon (Si), aluminum (Al), titanium (Ti),
germanium (Ge), phosphorus (P), boron (B), yttrium (Y), alkaline
earth element, sulfide element, rare earth element, and nitride
element.
[0039] Examples of the material of the phosphor emitting red
fluorescence include the following. However, the phosphor emitting
red fluorescence used in the embodiments is not limited
thereto.
[0040] Y.sub.2O.sub.2S:Eu,
[0041] Y.sub.2O.sub.2S:Eu+pigment,
[0042] Y.sub.2O.sub.3:Eu,
[0043] Zn.sub.3(PO.sub.4).sub.2:Mn,
[0044] (Zn,Cd)S:Ag+In.sub.2O.sub.3,
[0045] (Y,Gd,Eu)BO.sub.3,
[0046] (Y,Gd,Eu).sub.2O.sub.3,
[0047] YVO.sub.4:Eu,
[0048] La.sub.2O.sub.2S:Eu,Sm,
[0049] LaSi.sub.3N.sub.5:Eu.sup.2+,
[0050] .alpha.-sialon:Eu.sup.2+,
[0051] CaAlSiN.sub.3:Eu.sup.2+,
[0052] CaSiN.sub.x:Eu.sup.2+,
[0053] CaSiN.sub.x:Ce.sup.2+,
[0054] M.sub.2Si.sub.5N.sub.8:Eu.sup.2+,
[0055] (SrCa)AlSiN.sub.3:Eu.sup.X+,
[0056] Sr.sub.x(Si.sub.yAl.sub.3).sub.z(O.sub.xN):Eu.sup.X+
[0057] Examples of the material of the phosphor emitting green
fluorescence include the following. However, the phosphor emitting
green fluorescence used in the embodiments is not limited
thereto.
[0058] ZnS:Cu,Al,
[0059] ZnS:Cu,Al+pigment,
[0060] (Zn,Cd)S:Cu,Al,
[0061] ZnS:Cu,Au,Al+pigment,
[0062] Y.sub.3Al.sub.5O.sub.12:Tb,
[0063] Y.sub.3(Al,Ga).sub.5O.sub.12:Tb,
[0064] Y.sub.2SiO.sub.5:Tb,
[0065] Zn.sub.2SiO.sub.4:Mn,
[0066] (Zn,Cd)S:Cu,
[0067] ZnS:Cu,
[0068] ZnS:Cu+Zn.sub.2SiO.sub.4:Mn,
[0069] Gd.sub.2O.sub.2S:Tb,
[0070] (Zn,Cd)S:Ag,
[0071] Y.sub.2O.sub.2S:Tb,
[0072] ZnS:Cu,Al+In.sub.2O.sub.3,
[0073] (Zn,Cd)S:Ag+In.sub.2O.sub.3,
[0074] (Zn,Mn).sub.2SiO.sub.4,
[0075] BaAl.sub.12O.sub.19:Mn,
[0076] (Ba,Sr,Mg)O.aAl.sub.2O.sub.3:Mn,
[0077] LaPO.sub.4:Ce,Tb,
[0078] 3(Ba,Mg,Eu,Mn)O.8Al.sub.2O.sub.3,
[0079] La.sub.2O.sub.3.0.2SiO.sub.2.0.9P.sub.2O.sub.5:Ce,Tb,
[0080] CeMgAl.sub.11O.sub.19:Tb,
[0081] CeSc.sub.2O.sub.4:Ce,
[0082] (BrSr)SiO.sub.4:Eu,
[0083] .alpha.-sialon:Yb.sup.2+,
[0084] .beta.-sialon:Eu.sup.2+,
[0085] (SrBa)YSi.sub.4N.sub.7:Eu.sup.2+,
[0086] (CaSr)Si.sub.2O.sub.4N.sub.7:Eu.sup.2+,
[0087] Sr(SiAl)(ON):Ce
[0088] Examples of the material of the phosphor emitting blue
fluorescence include the following. However, the phosphor emitting
blue fluorescence used in the embodiments is not limited
thereto.
[0089] ZnS:Ag,
[0090] ZnS:Ag+pigment,
[0091] ZnS:Ag,Al,
[0092] ZnS:Ag,Cu,Ga,Cl,
[0093] ZnS:Ag+In.sub.2O.sub.3,
[0094] ZnS:Zn+In.sub.2O.sub.3,
[0095] (Ba,Eu)MgAl.sub.10O.sub.17,
[0096] (Sr,Ca,Ba,Mg).sub.10(PO.sub.4)6Cl.sub.2:Eu,
[0097] Sr.sub.10(PO.sub.4).sub.6Cl.sub.2:Eu,
[0098] (Ba,Sr,Eu)(Mg,Mn)Al.sub.10O.sub.17,
[0099] 10(Sr,Ca,Ba,Eu).6PO.sub.4.Cl.sub.2,
[0100] BaMg.sub.2Al.sub.16O.sub.25:Eu
[0101] Examples of the material of the phosphor emitting yellow
fluorescence include the following. However, the phosphor emitting
yellow fluorescence used in the embodiments is not limited
thereto.
[0102] Li(Eu,Sm)W.sub.2O.sub.8,
[0103] (Y,Gd).sub.3(Al,Ga).sub.5O.sub.12:Ce.sup.3+,
[0104] Li.sub.2SrSiO.sub.4:Eu.sup.2+,
[0105] (Sr(Ca,Ba)).sub.3SiO.sub.5:Eu.sup.2+,
[0106] SrSi.sub.2ON.sub.2.7:Eu.sup.2+
[0107] Examples of the material of the phosphor emitting
yellow-green fluorescence include the following. However, the
phosphor emitting yellow-green fluorescence used in the embodiments
is not limited thereto.
[0108] SrSi.sub.2ON.sub.2.7:Eu.sup.2+
[0109] If the mixing ratio of the phosphor is made lower, the color
gets close to blue (color temperature around 10000 K). If the
mixing ratio of the phosphor is made higher, the color gets close
to yellow (color temperature 6500-2800 K). Here, the phosphor mixed
is not limited to one kind, but a plurality of kinds of phosphors
may be mixed. For instance, it is possible to mix a phosphor
emitting red fluorescence, a phosphor emitting green fluorescence,
a phosphor emitting blue fluorescence, a phosphor emitting yellow
fluorescence, and a phosphor emitting yellow-green fluorescence.
Furthermore, the mixing ratio of a plurality of kinds of phosphors
can be varied to change the tint, such as bluish white light and
yellowish white light.
[0110] Examples of the resin mixed with phosphor can include epoxy
resin, silicone resin, methacrylic resin (PMMA), polycarbonate
(PC), cyclic polyolefin (COP), alicyclic acrylate (OZ),
allyldiglycol carbonate (ADC), acrylic resin, fluororesin, hybrid
resin of silicone resin and epoxy resin, and urethane resin.
[0111] The refractive index of the resin mixed with phosphor is
preferably made equal to or less than the refractive index of the
phosphor. The transmittance of the resin mixed with phosphor is
preferably set to 90% or more.
[0112] Here, in the case where light emitted from the light
emitting section 2 has a short wavelength from ultraviolet to blue
and high brightness, the resin forming the wavelength conversion
section 4 may be degraded. Thus, the resin forming the wavelength
conversion section 4 is preferably made less prone to degradation
by blue light. Examples of resins less prone to degradation by blue
light can include methylphenyl silicone, dimethyl silicone, and
hybrid resin of methylphenyl silicone and epoxy resin having a
refractive index of approximately 1.5.
[0113] However, the resin mixed with phosphor is not limited to
those illustrated above, but can be appropriately modified.
[0114] In the embodiment, in order to suppress detachment of
phosphor from the wavelength conversion section 4, the hardness of
the cured resin portion of the wavelength conversion section 4 is
set to within a prescribed range. For instance, the Shore D
hardness measured with a durometer type D (Shore D) pursuant to JIS
K 6253 is set to exceed 10.
[0115] In this case, the Shore D hardness of the cured resin
portion of the wavelength conversion section 4 can be controlled
by, e.g., adding an additive such as curing agent.
[0116] If cross-linking sites of the resin can be increased by
adding an additive such as curing agent, the Shore D hardness of
the cured resin portion of the wavelength conversion section 4 can
be increased. Thus, the Shore D hardness of the cured resin portion
of the wavelength conversion section 4 can be controlled by
appropriately changing the kind of the additive such as curing
agent and its added amount.
[0117] The suppression of detachment of phosphor will be described
later in detail.
[0118] The first electrode section 5 is provided on the
semiconductor section 2a and can be made of e.g. a double layer of
Ni (nickel)/Au (gold). In this case, for instance, the thickness of
the Ni (nickel) layer can be set to approximately 1 .mu.m, and the
thickness of the Au (gold) layer can be set to approximately 1
.mu.m. However, the material and thickness of the first electrode
section 5 are not limited to those illustrated above, but may be
appropriately modified. The shape of the first electrode section 5
can be e.g. a circular shape. However, the shape of the first
electrode section 5 is not limited to a circular shape, but may be
appropriately modified depending on the cross-sectional shape and
size of the first connecting section 6a described later.
[0119] The first conductive section 6 is provided so as to
penetrate between the bottom surface of the recess 12a and the end
surface of the sealing section 12. The first conductive section 6
is shaped like e.g. a circular cylinder, and can be made of a metal
material such as Cu (copper). The first conductive section 6 is
provided with a first connecting section 6a having a small
cross-sectional area. The first connecting section 6a is provided
on the first electrode section 5. Thus, the first conductive
section 6 is electrically connected to the semiconductor section 2a
through the first electrode section 5. However, the shape and
material of the first conductive section 6 and the first connecting
section 6a are not limited to those illustrated above, but can be
appropriately modified.
[0120] The first connecting member 7 is provided over one end
surface of the first conductive section 6 exposed from the sealing
section 12. The first connecting member 7 can be configured as a
so-called solder bump. In the case where the first connecting
member 7 is configured as a solder bump, the first connecting
member 7 can be shaped like a hemisphere, and its material can be a
solder material used for surface mounting. In this case, the solder
material used for surface mounting can be e.g. Sn-3.0Ag-0.5Cu
solder, Sn-0.8Cu solder, or Sn-3.5Ag solder.
[0121] However, the shape and material of the first connecting
member 7 are not limited to those illustrated above, but can be
appropriately modified depending on the method for mounting the
semiconductor light emitting device 1. For instance, the first
connecting member 7 can be shaped like a thin film, and made of
e.g. a double layer of Ni (nickel)/Au (gold).
[0122] Furthermore, the first connecting member 7 is not
necessarily needed, but may be appropriately provided depending on
the method for mounting the semiconductor light emitting device
1.
[0123] The second electrode section 8 is provided on the
semiconductor section 2c and can be made of e.g. a double layer of
Ni (nickel)/Au (gold). In this case, for instance, the thickness of
the Ni (nickel) layer can be set to approximately 1 .mu.m, and the
thickness of the Au (gold) layer can be set to approximately 1
.mu.m. However, the material and thickness of the second electrode
section 8 are not limited to those illustrated above, but may be
appropriately modified. The shape of the second electrode section 8
can be e.g. a circular shape. However, the shape of the second
electrode section 8 is not limited to a circular shape, but may be
appropriately modified depending on the cross-sectional shape and
size of the second connecting section 9a described later.
[0124] The second conductive section 9 is provided so as to
penetrate between the bottom surface of the recess 12a and the end
surface of the sealing section 12. The second conductive section 9
is shaped like e.g. a circular cylinder, and can be made of a metal
material such as Cu (copper). The second conductive section 9 is
provided with a second connecting section 9a having a small
cross-sectional area. The second connecting section 9a is provided
on the second electrode section 8. Thus, the second conductive
section 9 is electrically connected to the semiconductor section 2c
through the second electrode section 8. However, the shape and
material of the second conductive section 9 and the second
connecting section 9a are not limited to those illustrated above,
but can be appropriately modified.
[0125] The second connecting member 10 is provided over one end
surface of the second conductive section 9 exposed from the sealing
section 12. The second connecting member 10 can be configured as a
so-called solder bump. In the case where the second connecting
member 10 is configured as a solder bump, the second connecting
member 10 can be shaped like a hemisphere, and its material can be
a solder material used for surface mounting. In this case, the
solder material used for surface mounting can be e.g.
Sn-3.0Ag-0.5Cu solder, Sn-0.8Cu solder, or Sn-3.5Ag solder.
[0126] However, the shape and material of the second connecting
member 10 are not limited to those illustrated above, but can be
appropriately modified depending on the method for mounting the
semiconductor light emitting device 1. For instance, the second
connecting member 10 can be shaped like a thin film, and made of
e.g. a double layer of Ni (nickel)/Au (gold).
[0127] Furthermore, the second connecting member 10 is not
necessarily needed, but may be appropriately provided depending on
the method for mounting the semiconductor light emitting device
1.
[0128] The insulating section 11 is provided so as to bury the
recess 12a provided in the sealing section 12. The insulating
section 11 is formed from an insulating material. For instance, the
insulating section 11 can be formed from an inorganic material such
as SiO.sub.2, or a resin.
[0129] Here, in the case where light emitted from the light
emitting section 2 has a short wavelength from ultraviolet to blue
and high brightness, the resin forming the insulating section 11
may be degraded. Thus, in the case where the insulating section 11
is formed from a resin, the resin is preferably made less prone to
degradation by blue light. Examples of resins less prone to
degradation by blue light can include methylphenyl silicone and
dimethyl silicone having a refractive index of approximately
1.5.
[0130] The sealing section 12 is provided on the second major
surface M2 side. The sealing section 12 seals the first conductive
section 6 and the second conductive section 9 while exposing the
end portion of the first conductive section 6 and the end portion
of the second conductive section 9.
[0131] The sealing section 12 can be formed from e.g. a
thermosetting resin. The sealing section 12 also serves to seal the
light emitting section 2, the first electrode section 5, and the
second electrode section 8. Here, the sealing section 12 can be
formed integrally with the insulating section 11.
[0132] Next, suppression of chromaticity shift is further
illustrated.
[0133] FIG. 2 is a schematic view for illustrating the emission
characteristic of the light emitting section 2. The emission
characteristic is shown by monotone shading, getting darker toward
blue and lighter toward yellow.
[0134] In the case illustrated in FIG. 2, the color is yellow in
the central portion of the light emitting section 2 and gets blue
toward the periphery.
[0135] Such variation in the emission characteristic of the light
emitting section 2 may result in increasing the chromaticity shift
in which the chromaticity varies with the direction of viewing the
semiconductor light emitting device 1.
[0136] According to the findings obtained by the inventor, the
chromaticity shift can be suppressed by changing the optical path
length inside the wavelength conversion section in accordance with
the emission characteristic of the light emitting section.
[0137] The following description is illustrated with reference to
the case where the emission characteristic of the light emitting
section 2 is as illustrated in FIG. 2. That is, the following
description is illustrated with reference to the case where the
color is yellow in the central portion of the light emitting
section 2 and gets blue toward the periphery. Examples of the light
emitting section 2 having such emission characteristic can include
those made of e.g. a nitride semiconductor such as GaN (gallium
nitride).
[0138] FIG. 3 is a schematic sectional view illustrating a
semiconductor light emitting device 100 according to a comparative
example.
[0139] As shown in FIG. 3, the semiconductor light emitting device
100 includes a light emitting section 2, a wavelength conversion
section 104, a first electrode section 5, a first conductive
section 6, a first connecting member 7, a second electrode section
8, a second conductive section 9, a second connecting member 10, an
insulating section 11, and a sealing section 12. That is, the
semiconductor light emitting device 100 does not include the light
transmitting section 3.
[0140] FIG. 4 is a schematic graph for illustrating the
chromaticity shift.
[0141] Here, FIG. 4 is obtained by simulation analysis of light
emitted from a prescribed position and transmitted through the
wavelength conversion section. The horizontal axis of FIG. 4
represents view angle, with 0.degree. corresponding to the case of
viewing the semiconductor light emitting device from its front
side, and 90.degree. and -90.degree. corresponding to the case of
viewing the semiconductor light emitting device from its lateral
side. The vertical axis of FIG. 4 represents chromaticity, getting
yellow upward and blue downward in the graph. The chromaticity
shift is represented by the chromaticity difference with respect to
the view angle. Thus, for instance, the chromaticity shift is
smaller as the difference between the chromaticity at 0.degree. and
the chromaticity at 90.degree. or -90.degree. gets smaller.
[0142] As seen from FIG. 4, in the plate-like wavelength conversion
section 104 without the light transmitting section 3, the
chromaticity shift is large.
[0143] According to the findings obtained by the inventor, the
chromaticity shift can be suppressed by a wavelength conversion
section having a shape in which the optical path length inside the
wavelength conversion section is adjusted to suppress the
chromaticity shift in accordance with the emission characteristic
of the light emitting section. That is, the chromaticity shift can
be suppressed by optimizing the optical path length inside the
wavelength conversion section in accordance with the emission
characteristic of the light emitting section.
[0144] Thus, in the embodiment, by providing a light transmitting
section, the wavelength conversion section is shaped so as to be
able to suppress the chromaticity shift. For instance, in the case
illustrated in FIG. 1, a light transmitting section 3 having a
concave surface 3a is provided to form a convex surface 4a in the
wavelength conversion section 4. Thus, the optical path length
inside the wavelength conversion section 4 is optimized in
accordance with the emission characteristic of the light emitting
section 2. In this case, the suppression of chromaticity shift can
be controlled by changing the curvature radius R of the surface
4a.
[0145] Here, the shape of the wavelength conversion section formed
by providing a light transmitting section is not limited to those
having a convex shape. For instance, a light transmitting section
having a convex shape can be provided to form a wavelength
conversion section having a concave shape. Alternatively, a light
transmitting section with a flat surface around a convex shape can
be provided to form a wavelength conversion section with a flat
surface around a concave shape. Furthermore, a convex shape, a
concave shape, and a flat surface may be appropriately combined.
Furthermore, the curvature radius may be appropriately changed.
That is, the shape of the wavelength conversion section only needs
to be formed so that the optical path length inside the wavelength
conversion section is optimized in accordance with the emission
characteristic of the light emitting section 2.
[0146] In the case of changing the curvature radius, the curvature
radius of the convex shape is preferably set to 250 nm or more.
Furthermore, the curvature radius of the concave shape is
preferably set to 200 nm or more.
[0147] The chromaticity shift can be further suppressed by changing
the kinds of phosphors and the distribution of their ratio in the
plane of the wavelength conversion section. For instance, in the
case where the color gets blue toward the periphery of the light
emitting section 2 as illustrated in FIG. 2, the ratio of the
phosphor emitting yellow fluorescence can be increased toward the
periphery of the wavelength conversion section. Then, white light
can be emitted in nearly the entire region of the wavelength
conversion section.
[0148] Next, the suppression of detachment of phosphor is further
illustrated.
[0149] Productivity can be improved by integrally forming a
plurality of semiconductor light emitting devices 1 and then
singulating each semiconductor light emitting device 1. However, in
the case where a wavelength conversion section 4 including phosphor
is provided, the phosphor may be detached from the wavelength
conversion section 4 when each semiconductor light emitting device
1 is singulated.
[0150] According to the findings obtained by the inventor,
detachment of phosphor from the wavelength conversion section in
singulating the semiconductor light emitting device can be
suppressed by setting the hardness of the cured resin portion of
the wavelength conversion section to within a prescribed range.
[0151] TABLE 1 illustrates the relationship between the hardness of
the cured resin portion of the wavelength conversion section and
the detachment of phosphor.
[0152] FIGS. 5A to 5D are schematic views for illustrating the
detachment of phosphor.
[0153] Here, FIGS. 5A to 5D illustrate the cutting surface of the
semiconductor light emitting device singulated by the blade dicing
method. The number of revolutions of the dicing blade was set to
40000 rpm.
TABLE-US-00001 TABLE 1 Sample 1 2 3 4 Resin Dimethyl Epoxy + phenyl
Dimethyl Phenyl silicone silicone silicone silicone Viscosity 340
1470 3000 2200 (mPa s) Refractive 1.41 1.48 1.53 1.54 index
Hardness A34 (.ltoreq.D10) D74 A87 (D30) D60~D70 Detachment of
Observed None None None phosphor (see (see FIG. 5B) (see (see FIG.
5A) FIG. 5C) FIG. 5D)
[0154] In Sample #1 of TABLE 1, the hardness of the cured resin
portion of the wavelength conversion section is 34 in the Shore A
hardness (10 or less in the Shore D hardness).
[0155] In such cases, as seen from FIG. 5A, a recess 110 occurs in
the cutting surface, and the phosphor is detached.
[0156] In Sample #2, the hardness of the cured resin portion of the
wavelength conversion section is 74 in the Shore D hardness.
[0157] In Sample #3, the hardness of the cured resin portion of the
wavelength conversion section is 87 in the Shore A hardness (30 in
the Shore D hardness).
[0158] In Sample #4, the hardness of the cured resin portion of the
wavelength conversion section is 60-70 in the Shore D hardness.
[0159] That is, in Samples #2-4, the hardness of the cured resin
portion of the wavelength conversion section exceeds 10 in the
Shore D hardness.
[0160] In such cases, as seen from FIGS. 5B to 5D, no recess 110
occurs in the cutting surface, and the detachment of phosphor can
be suppressed.
[0161] That is, if the hardness of the cured resin portion of the
wavelength conversion section is set to exceed 10 in the Shore D
hardness, the detachment of phosphor can be suppressed.
[0162] Furthermore, if the hardness of the cured resin portion of
the wavelength conversion section is set to 30 or more in the Shore
D hardness, the detachment of phosphor can be further
suppressed.
[0163] Next, the operation of the semiconductor light emitting
device 1 is illustrated.
[0164] By voltage application to the first conductive section 6, a
potential is applied to the semiconductor section 2a through the
first electrode section 5. By voltage application to the second
conductive section 9, a potential is applied to the semiconductor
section 2c through the second electrode section 8. When potentials
are thus applied to the semiconductor section 2a and the
semiconductor section 2c, holes and electrons are recombined in the
active section 2b to generate light. Part of the light emitted from
the active section 2b is transmitted through the semiconductor
section 2a and the light transmitting section 3 and injected into
the wavelength conversion section 4. The light injected into the
wavelength conversion section 4 is wavelength converted by phosphor
and emitted outward from the wavelength conversion section 4. For
instance, blue light emitted from the active section 2b is mixed
with the (yellow, or red and green) light excited by the blue light
into white light. The white light is emitted outward from the
wavelength conversion section 4. In the embodiment, the optical
path length inside the wavelength conversion section 4 is optimized
in accordance with the emission characteristic of the light
emitting section 2. That is, by providing a light transmitting
section 3 having a prescribed shape, the wavelength conversion
section 4 is formed to include a surface 4a such that the optical
path length therein is adjusted to suppress chromaticity shift in
accordance with the emission characteristic of the light emitting
section 2. Thus, the chromaticity shift can be suppressed. For
instance, the chromaticity shift can be reduced irrespective of the
direction of viewing the semiconductor light emitting device 1
emitting white light. Thus, white light can be emitted in nearly
the entire region of the wavelength conversion section 4.
[0165] Furthermore, the hardness of the cured resin portion of the
wavelength conversion section 4 is set to exceed 10 in the Shore D
hardness. Thus, it is possible to suppress detachment of phosphor
from the wavelength conversion section 4 in singulating the
semiconductor light emitting device 1.
[0166] Next, a method for manufacturing a semiconductor light
emitting device according to the embodiment is illustrated.
[0167] FIG. 6 is a flow chart for illustrating the method for
manufacturing a semiconductor light emitting device according to
the embodiment.
[0168] This method relates to the case of integrally forming a
plurality of semiconductor light emitting devices and then
singulating each semiconductor light emitting device.
[0169] First, on a substrate made of e.g. sapphire, a semiconductor
section 2a, an active section 2b and a semiconductor section 2c
having a prescribed shape are stacked in this order (step S1).
[0170] Here, these sections can be stacked by using e.g. a known
vapor phase growth method. Examples of the vapor phase growth
method can include the metal organic chemical vapor deposition
(MOCVD) method, the hydride vapor phase epitaxy (HVPE) method, and
the molecular beam epitaxy (MBE) method.
[0171] Next, a first electrode section 5 is formed on the
semiconductor section 2a, and a second electrode section 8 is
formed on the semiconductor section 2c (step S2).
[0172] Here, the first electrode section 5 and the second electrode
section 8 can be formed by combining various physical vapor
deposition (PVD) methods such as vacuum evaporation and sputtering,
various chemical vapor deposition (CVD) methods, and plating
methods with lithography and etching techniques.
[0173] Next, over the stacked body thus stacked on the substrate,
an insulating section 11 having a prescribed shape is formed (step
S3).
[0174] Here, the insulating section 11 can be formed by combining
various physical vapor deposition (PVD) methods such as vacuum
evaporation and sputtering and various chemical vapor deposition
(CVD) methods with lithography and etching techniques.
[0175] Next, over the insulating section 11, a sealing section 12
having a prescribed shape is formed (step S4).
[0176] Here, the sealing section 12 can be formed by combining
various physical vapor deposition (PVD) methods such as vacuum
evaporation and sputtering and various chemical vapor deposition
(CVD) methods with lithography and etching techniques.
[0177] Next, a first conductive section 6 and a second conductive
section 9 are formed (step S5).
[0178] Here, the first conductive section 6 and the second
conductive section 9 can be formed by combining various physical
vapor deposition (PVD) methods such as vacuum evaporation and
sputtering, various chemical vapor deposition (CVD) methods, and
plating methods with lithography and etching techniques.
[0179] Next, a first connecting member 7 is formed on the end
surface of the first conductive section 6, and a second connecting
member 10 is formed on the end surface of the second conductive
section 9 (step S6).
[0180] Here, the first connecting member 7 and the second
connecting member 10 can be formed by combining various physical
vapor deposition (PVD) methods such as vacuum evaporation and
sputtering, various chemical vapor deposition (CVD) methods, and
plating methods with lithography and etching techniques.
[0181] Next, the stacked body thus formed is peeled from the
substrate (step S7).
[0182] Here, the stacked body can be peeled from the substrate by
e.g. the laser lift-off method.
[0183] Next, the peeled stacked body is reversed, and a light
transmitting section 3 having a prescribed shape is formed on the
semiconductor section 2a (step S8).
[0184] Here, a resin, for instance, can be applied and shaped to
form the light transmitting section 3.
[0185] For instance, the light transmitting section 3 can be formed
by the nanoimprint method or the molding method.
[0186] Here, in the case of using the UV nanoimprint method, the
resin is irradiated with ultraviolet radiation while a shaping die
is pressed to the resin. Thus, the shaped resin is cured to form
the light transmitting section 3. In the case of using the UV
nanoimprint method, the shaping die is formed from an ultraviolet
transmissive material, and the resin is made of an ultraviolet
curable resin.
[0187] In the case of using the molding method, heating is
performed while a shaping die is pressed to the resin. Thus, the
shaped resin is cured to form the light transmitting section 3. In
the case of using the molding method, the shaping die is provided
with a heater, and the resin is made of a thermosetting resin.
[0188] Here, a light transmitting section having various shapes can
be formed by changing the shape of the shaping surface of the
shaping die.
[0189] The method for forming the light transmitting section is not
limited to the nanoimprint method and the molding method, but can
be appropriately modified.
[0190] For instance, the light transmitting section may be formed
by stacking resin layers in a prescribed shape using a microdroplet
application method such as the ink jet method and the dispense
method.
[0191] Next, over the light transmitting section 3, a wavelength
conversion section 4 is formed (step S9).
[0192] For instance, a resin mixed with prescribed phosphor can be
applied over the light transmitting section 3, shaped in a
plate-like configuration, and cured to form the wavelength
conversion section 4. Here, the hardness of the cured resin portion
of the wavelength conversion section is set to exceed 10 in the
Shore D hardness.
[0193] For instance, as described above, the hardness after curing
is set to exceed 10 in the Shore D hardness by appropriately adding
an additive such as curing agent.
[0194] Application and shaping of the resin mixed with phosphor can
be based on the printing and application method such as the
squeegee method, screen method, and spin method.
[0195] Here, because the light transmitting section having a
prescribed shape is provided, the optical path length inside the
wavelength conversion section can be optimized in accordance with
the emission characteristic of the light emitting section.
[0196] That is, in the process of forming the wavelength conversion
section, the wavelength conversion section is formed to include a
shape such that the optical path length therein is adjusted to
suppress chromaticity shift in accordance with the emission
characteristic of the light emitting section.
[0197] Thus, the chromaticity shift can be suppressed.
[0198] Next, a plurality of integrally formed semiconductor light
emitting devices are singulated (step S10).
[0199] Here, the semiconductor light emitting device can be
singulated by e.g. the blade dicing method.
[0200] In this case, the wavelength conversion section is cut.
However, the hardness of the cured resin portion of the wavelength
conversion section is set to exceed 10 in the Shore D hardness.
Hence, detachment of phosphor from the wavelength conversion
section in singulating the semiconductor light emitting device can
be suppressed.
[0201] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
invention.
* * * * *