JP3486345B2 - Semiconductor light emitting device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device that emits light by combining a semiconductor light emitting element such as an LED (light emitting diode) and a plurality of types of phosphors.

[0002]

2. Description of the Related Art A semiconductor light emitting device in which a semiconductor light emitting element and a phosphor are combined is capable of freely changing the emission color by selecting the combination and type of the semiconductor light emitting device. That is, by converting the wavelength of the primary light emitted from the semiconductor light emitting element by the phosphor and extracting it as secondary light, the degree of freedom in selecting the obtained wavelength can be greatly expanded.

[0003]

However, as a result of trial and study conducted by the present inventor, the conventional semiconductor light emitting device in which a semiconductor light emitting element and a plurality of types of phosphors are combined has the following problems. Do you get it.

FIG. 9 is a sectional view showing a schematic structure of a conventional semiconductor light emitting device. That is, in the semiconductor light emitting device of the same figure, the LED chip 101 is mounted on the bottom surface of the concave cup portion formed on the lead frame 102, and the wire 1
Wiring is made by 06 and 107, and phosphors 111 to 113 are applied. Here, the LED 101 emits light in the ultraviolet region, and the phosphor absorbs the ultraviolet light and emits red light, and the red (R) phosphor 111 emits green light and the green light ( G) Phosphor 112, a mixture of blue (B) phosphor that emits blue light. In this way, the semiconductor light emitting device shown in FIG. 9 can obtain the white light of RGB by wavelength-converting the ultraviolet light from the LED 101.

However, when the present inventor prototyped and evaluated the semiconductor light emitting device as shown in FIG. 9, it was found that there was a problem that mixed spots, that is, "unevenness" of light emission was caused. Specifically, for example, when the semiconductor light emitting device of FIG. 9 is viewed from the light extraction direction, the emission color is different between the center of the light emitting portion, that is, near the vertically upper portion of the LED 101, and the peripheral portion at the end thereof. The problem was discovered.

As a result of further detailed study by the present inventor, such "unevenness" of light emission is due to the difference in specific gravity and particle size of the phosphors of RGB, and the resin applied and dissolved. It was found that this occurs in the curing process of. Further, it has been found that the step on the phosphor coated surface due to the presence of the LED chip 101 has a great influence on this phenomenon.

That is, as can be seen from FIG.
The phosphor layer coated on the upper part of 101 and the phosphor layer coated on the cup portion around the LED 101 have significantly different coating thicknesses. The thickness of the LED 101 is usually 100
˜200 μm, and the coating thickness of the phosphor applied thereon is often several tens of μm. In other words, the coating thickness of the phosphor differs several times between the upper part of the LED and the cup part around the LED.

When the coating thickness is different, the time until the mixture of the coated phosphor and the solvent is dried and cured is different, and the segregation state of the RGB phosphor particles is different due to the difference in the specific gravity of the phosphor. Here, as a typical value of the particle size and specific gravity of the phosphor, the particle size of the red (R) phosphor is about 6 μm.
m, specific gravity is about 6.4. The green (G) phosphor has a particle size of about 3 μm and a specific gravity of about 3.8, and the blue (B) phosphor has a particle size of about 4 μm and a specific gravity of about 4.2. When a plurality of phosphor particles having different particle diameters and specific gravities are mixed and applied in a solvent as described above, the segregation state of the phosphor particles varies depending on the coating thickness.

For example, in a portion having a large coating thickness, phosphor particles having a large specific gravity segregate more significantly downward. As a result, in the upper part of the LED 101 and its surroundings,
Since the mixed state of the phosphors is different and the balance of emission colors is different, "unevenness" of light emission occurs.

As shown in FIG. 9, due to the existence of the step due to mounting the LED chip, the mixing ratio is different between the upper part and the peripheral part of the LED chip due to the difference in the specific gravity of the phosphor particles, and as a result, the light emitted from the LED is emitted. It is easy to see that there is a difference in the emission color between the light converted directly above and the light reflected laterally in the reflection plate.
The present invention has been made based on the recognition of such unique problems. That is, an object of the invention is to provide a semiconductor light emitting device capable of eliminating "unevenness" in light emission by making the coating thickness of the phosphor uniform.

[0011]

Means for Solving the Problems The present invention is intended to prevent mixing unevenness caused by the difference in specific gravity and particle size of phosphors when a plurality of kinds of phosphors are applied to the periphery of a light emitting element. The structure is characterized in that the light emitting element is mounted so as to be embedded on the mounting member, and a plurality of phosphors are applied to the substantially flat surface thus obtained. By doing so, it is possible to uniformly mix the phosphors or apply them on a uniform layer, and it is possible to realize light emission without color spots.

That is, the semiconductor light emitting device of the present invention comprises a mounting member, a light emitting element mounted on the mounting member,
A phosphor that absorbs primary light emitted from the light emitting device and emits secondary light having a wavelength different from that of the primary light;
In the semiconductor light emitting device, the phosphor is formed so as to have a constant thickness on a substantially flat surface.

Alternatively, in the semiconductor light emitting device of the present invention, the mounting member, the light emitting element mounted on the mounting member, the primary light emitted from the light emitting element, and a wavelength different from the primary light are absorbed. And a phosphor that emits secondary light, the mounting member having a recess on a main surface on which the phosphor is applied, and the light emitting element is the mounting member. Of the mounting member is mounted so as to be embedded in the recess, and the main surface of the mounting member and the upper surface of the light emitting element form a substantially flat coating surface by being provided in substantially the same plane, The phosphor is applied to the application surface so as to have a constant thickness.

Here, the phosphor includes two or more kinds of phosphors having specific gravities different from each other.

Further, the two or more kinds of phosphors are formed and laminated in layers for each kind.

Alternatively, the semiconductor light emitting device of the present invention includes a light emitting element and a first light emitting element that absorbs primary light emitted from the light emitting element and emits light having a first wavelength different from the primary light. A phosphor and a second that absorbs primary light emitted from the light emitting element and emits light of a second wavelength different from the primary light
And a second phosphor, wherein the first phosphor is provided on a first region of a light emitting surface of the light emitting element, and the second phosphor is It is characterized in that it is provided on a second area different from the first area on the light emitting surface of the light emitting element.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing the structure of a main part of a semiconductor light emitting device according to a first embodiment of the present invention.
In the figure, 11 is an LED chip, and 12 is a lead frame for mounting the LED. 13 is a red (R) phosphor, 14 is a green (G) phosphor, and 15 is a blue (B) phosphor, which absorbs the light from the LED 11 and emits secondary light in each wavelength band. is there. 16,
Reference numeral 17 is a wire for supplying a drive current to the LED, which is bonded to the electrode of the LED and the lead portion of the lead frame, respectively.

The semiconductor light emitting device of the present invention is different from the conventional example in that the lead frame 12 is provided with a recess 12A, and
The ED chip 11 is mounted so as to be embedded in the recess 12A. According to the invention, an LED
Since the step due to 11 is not generated, the coating thickness of the phosphor around the LED can be made constant. As a result, it is possible to make the segregation state of the phosphor uniform, as shown in FIG.
With respect to the above-mentioned "unevenness" of light emission, it can be eliminated.

Further, in this embodiment, each of the RGB phosphors is formed into a layer. That is, a layer made of the R phosphor 13 is provided as the first layer, a layer made of the G phosphor 14 is provided as the second layer, and a B layer is used as the third layer.
A layer made of the phosphor 15 is provided. According to the present invention, the coating thickness of the phosphor can be made uniform around the LED 11, so that such a three-layer structure can be realized reliably and easily.

The method of manufacturing the semiconductor light emitting device of FIG. 1 is as follows. That is, the LED chip 11 is attached to the frame 1
After mounting on 2, the resin containing the R phosphor 13 is applied and cured, then the resin containing the G phosphor 14 is applied and cured, and then the resin containing the B phosphor 15 is applied. Then, it is cured and created. Here, the amount and order of the phosphors to be applied can be appropriately determined in consideration of the conversion efficiency of each phosphor and the scattering inside the application region.

Here, the planar shape of the LED 11 is usually a square shape with one side of 400 to 500 μm, but in consideration of the processing accuracy of the lead frame, the error in mounting the LED 11, and the like, the recess 12A of the lead frame 12 is taken into consideration.
The opening size is 40% to 5
It is desirable to form a large size of about 0 μm. In this case, a gap is formed on both sides of the LED, but with such a size, there is no risk of adverse effects due to uneven coating.

When a bias current was supplied to the thus obtained semiconductor light emitting device through the wires 16 and 17,
Uniform white light emission without color spots was obtained when viewed from above the LED. Further, it was found that the present semiconductor light emitting device has a good color purity with respect to the directional angle, and is also superior to the device having the conventional structure in this respect.

FIG. 2 is a schematic sectional view illustrating the configuration of an LED mounted on the semiconductor light emitting device of FIG. 30 in the figure
1 is a sapphire substrate, 302 is an n-type GaN contact layer, 303 is an n-type AlGaN cladding layer, and 304 is In.
GaN active layer, 305 is p-type AlGaN cladding layer, 3
06 is a p-type GaN contact layer, 307 is a p-side electrode, 3
Reference numeral 08 is an n-side electrode. The LED of FIG. 2 can emit light of extremely high intensity in the wavelength range of blue to ultraviolet, and is therefore suitable for use in combination with a phosphor.

The illustrated LED has an n-side electrode 308.
Although there is a stepped portion between the surface on which the p-side electrode 307 is formed and the surface on which the p-side electrode 307 is formed, the height of the stepped portion is at most several μm or less and does not affect the segregation state of the phosphor.

The light emitting device that can be used in the present invention is not limited to the LED shown in FIG. 2 as long as it has sufficient characteristics (emission wavelength, emission intensity, etc.) to excite the phosphor. It can be produced by appropriately modifying the laminated structure and materials. For example, the substrate 301 is not limited to sapphire, but other materials such as spinel, MgO, and S can be used.
cAlMgO ₄ , LaSrGaO ₄ , (LaSr) (Al
Insulating substrate such as Ta) O ₃ or SiCSi, GaA
The same effects can be obtained by using a conductive substrate such as s or GaN in the same manner. Here, in the case of the ScAlMgO ₄ substrate, the (0001) plane, (LaSr) (AlT
a) In the case of an O ₃ substrate, it is desirable to use the (111) plane.

As a material which can be used as the nitride semiconductor, B _x In _y Al _z Ga _(1-xyz) N (O≤
x ≦ 1, O ≦ y ≦ 1, O ≦ z ≦ 1), which may be III-V group compound semiconductors of any composition represented by chemical formulas. Further, as the V group element, phosphorus can be used in addition to N. A mixed crystal containing (P) or arsenic (As) may also be included. Furthermore, III-V other than these nitride semiconductors
Group compound semiconductor, II-VI group compound semiconductor, or Si
C and the like can be used as well.

Next, a second embodiment of the present invention will be described. FIG. 3 is a schematic sectional view showing a semiconductor light emitting device according to the second embodiment of the present invention. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals.
The semiconductor light emitting device of the present embodiment has RGB phosphors 13 to 1
This is different from the first embodiment in that 5 is mixed with resin and applied and cured. That is, in this embodiment, the phosphors 13 to 15 are randomly mixed.

As described above with reference to FIG. 9, in the conventional semiconductor light emitting device, a lot of "unevenness" in light emission occurs due to the presence of the step difference due to the LED, whereas in the present embodiment, the LED 11 is used. Since it is embedded in the lead frame 12 to substantially eliminate the step, the "unevenness" of light emission can be eliminated even when the phosphors are randomly mixed. When randomly mixing phosphors in this way,
It can be manufactured more easily than when applied in layers as illustrated in FIG.

When a bias current was supplied to the thus obtained semiconductor light emitting device, uniform white light emission without color spots was observed when observed from above the LED 11. That is, according to the present invention, it is possible to obtain uniform light emission without "unevenness" of light emission even if the RGB phosphors are mixed and applied as in the conventional case. It was also found that this device has a good color purity with respect to the directivity angle, and is superior to the device having the conventional structure also in this respect.

Next, a third embodiment of the present invention will be described. FIG. 4 is a schematic sectional view showing a semiconductor light emitting device according to a third embodiment of the present invention. The semiconductor light emitting device of this embodiment is different in that the substrate 22 is used instead of the above-described lead frame as a mounting member for mounting the light emitting element. That is, a concave cup portion is formed on the substrate 22, and a concave portion 22A is provided on the bottom surface thereof. The LED 11 is mounted so as to be embedded in the recess 22A and is wired by the wires 16 and 17.

Then, the phosphors 13 to 15 are applied to the bottom surface of the cup portion which is a substantially flat surface and the top surface of the LED 11.

Also in this embodiment, since the coated surface of the phosphor has no step and is a substantially flat surface, the uneven segregation described above with reference to FIG. 9 does not occur. As a result, uniform light emission can be obtained.

In FIG. 4, the RGB phosphor 13 is used.
1 to 15 are mixed together and applied randomly, but as illustrated in FIG. 1, the phosphors 13 to 15 may be applied in layers.

Next, a fourth embodiment of the present invention will be described. FIG. 5 is a schematic sectional view showing a semiconductor light emitting device according to the fourth embodiment of the present invention. Also in the semiconductor light emitting device of this embodiment, the LED 11 is mounted on the substrate 22 as in the third embodiment described above. However, this embodiment is different in that the cup portion of the substrate 22 is filled with the resin 25. That is, a concave cup portion is formed on the substrate 22, and a concave portion 22A is formed on the bottom surface thereof.
Is provided. The cup portion is embedded with resin 25, and the phosphors 13 to 15 are applied to the surface of the resin 25.

Also in this embodiment, since the coated surface of the phosphor, that is, the surface of the resin 25 is a substantially flat surface without a step, the uneven segregation described above with reference to FIG. 9 occurs. There is no such thing. As a result, uniform light emission can be obtained. Further, according to the present embodiment, since the LED 11 is sealed with the resin 25,
It is possible to prevent deterioration or failure of the LED due to intrusion of water or various corrosive atmospheres. As a result, the reliability of the semiconductor light emitting device can be improved.

In FIG. 5, the RGB phosphor 13 is used.
1 to 15 are mixed together and applied randomly, but as illustrated in FIG. 1, the phosphors 13 to 15 may be applied in layers. In addition, in FIG.
However, the present embodiment is not limited to this, and the recessed portion 22A is not formed in the substrate 22, and the LED 11 is mounted on the flat mount surface on the bottom surface of the cup portion.
May be mounted.

Next, a fifth embodiment of the present invention will be described. FIG. 6 is a schematic sectional view showing a semiconductor light emitting device according to the fifth embodiment of the present invention. Also in the figure, the same reference numerals are given to the same structural parts as those of the above-described first and second embodiments. In the figure, 30 is L
The lens is made of a resin that is transparent to the primary light emitted from the ED 11.

The present embodiment is characterized in that the LED 11 is embedded and mounted on the lead frame 12, the lens 30 made of a transparent resin is formed, and the RGB phosphor is applied to the surface thereof. Since the surface of the lens 30 does not have a step, the unevenness of the segregation state as described above with reference to FIG. 9 does not occur when the phosphor is applied. As a result, uniform light emission can be obtained.

Further, according to this embodiment, the lens 30
By providing the above, the directional angle can be further widened, and it can be widely applied to applications such as display and illumination. Also,
FIG. 6 exemplifies a structure using a lead frame, but if it is integrated by mounting on a flat substrate, its application will be greatly expanded and the advantages of the present invention can be further brought out.

Although FIG. 6 shows an example in which the LED 11 is mounted by being embedded in the lead frame 12, the present embodiment is not limited to this, and a flat mount surface is formed without forming a recess in the lead frame 12. The LED 11 may be mounted on.

Further, the phosphors 13 to 15 are not applied in layers as shown in FIG.
You may mix 15 together and apply it at random.

Next, a sixth embodiment of the present invention will be described. FIG. 7 is a schematic sectional view showing a semiconductor light emitting device according to a sixth embodiment of the present invention. Also in this figure, the same parts as those in the first and second embodiments described above are designated by the same reference numerals. Reference numeral 60 in the figure denotes an LED in which the light emitting portion is divided into three regions. In this embodiment, the LED 60
It is characterized in that the RGB phosphors 13 to 15 are separately applied onto the respective three divided light emitting regions. That is, the LED 60 is divided into three regions by the light shielding plate 62, and one of the RGB phosphors 13 to 15 is applied to each region. Each of the applied phosphors absorbs the primary light from the LED 60 and emits the secondary light of each emission wavelength.

According to this embodiment, it is possible to separately take out the emitted light of each of RGB in one semiconductor light emitting device, or it is possible to freely express a mixed color thereof.

FIG. 8 is a schematic sectional view showing an LED that can be used in the sixth embodiment. In the figure, the same reference numerals are given to the same structural parts as those in FIG. 3 described above. In the figure, 701 is an n-type GaN substrate.
LED by creating elements on this conductive substrate
Electrodes can be formed on the upper and lower surfaces, respectively. The light emitting region is separated by etching so as to penetrate from the p-type GaN contact layer 306 to the n-type GaN layer 302. After that, a p-side electrode 307 is formed on the p-type GaN contact layer 306, and a common n-side electrode 308 is formed on the back surface of the n-type GaN substrate 701 to complete the present device.

In the semiconductor light emitting device of FIG. 7,
By providing the light shielding plate 62, excitation of the phosphor from other adjacent regions is prevented. Other than the one shown in the figure, the spacing between the light emitting regions may be widened, or the phosphor may be separated using a material that absorbs the excitation light or a resin containing an absorber. Also in this embodiment,
It is possible to obtain uniform light emission without color spots.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the light-emitting element used in each embodiment may be a light-emitting element of another material system having a wavelength and emission intensity sufficient for exciting a phosphor, in addition to the LED using a nitride semiconductor. Further, in each embodiment, the case where three kinds of phosphors of RGB are used as the phosphors is illustrated, but the present invention is effective in a combination of two or more kinds of different kinds. For example, even when white light is obtained by combining a phosphor that emits blue secondary light and a phosphor that emits yellow secondary light, the present invention can be similarly applied and similar effects can be obtained. . Other various modifications are possible without departing from the scope of the present invention.

[0048]

According to the present invention, by mounting a light emitting element such as an LED on a mounting member such as a lead frame in an embedded form, the phosphor coated surface is made substantially flat. By applying the phosphor on this flat surface, the coating thickness is made uniform, and the segregation state caused by the difference in the specific gravity and particle size of the phosphor particles is made uniform, thereby eliminating the "unevenness" of light emission. be able to.

Further, according to the present invention, the color purity of the semiconductor light emitting device can be increased, and the directivity of the color purity can be improved.

Furthermore, according to the present invention, even when a single phosphor is used, the segregation state is made uniform, so that
The effect that the uneven intensity of the next light can be eliminated and uniform light emission can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a main configuration of a semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating the configuration of an LED mounted on the semiconductor light emitting device of FIG.

FIG. 3 is a schematic sectional view showing a semiconductor light emitting device according to a second embodiment of the invention.

FIG. 4 is a schematic sectional view showing a semiconductor light emitting device according to a third embodiment of the invention.

FIG. 5 is a schematic sectional view showing a semiconductor light emitting device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing a semiconductor light emitting device according to a fifth embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a semiconductor light emitting device according to a sixth embodiment of the present invention.

FIG. 8 is an L that can be used in the sixth embodiment.
It is a schematic sectional drawing showing ED.

FIG. 9 is a cross-sectional view showing a schematic configuration of a conventional semiconductor light emitting device.

[Explanation of symbols]

11, 60, 101 LED chips 12,102 Lead frame 13,111 Red (R) phosphor 14,112 Green (G) phosphor 15,113 Blue (B) phosphor 16, 106 n-side gold wire 17, 107 p side gold wire 22 Substrate 25 resin 30 lenses 62 light shield 301 Sapphire substrate 302 n-type GaN contact layer 303 n-type AlGaN cladding layer 304 InGaN active layer 305 p-type AlGaN cladding layer 306 p-type GaN contact layer 307 p-side electrode 308 n-side electrode 701 GaN substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 10-107325 (JP, A) JP 7-15046 (JP, A) JP 11-40858 (JP, A) Registered utility model 3048368 ( JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 33/00

Claims (3)

(57) [Claims] 1. A mounting member, a light emitting element mounted on the mounting member, primary light emitted from the light emitting element, and secondary light having a wavelength different from that of the primary light is emitted. And a phosphor, wherein the mounting member has a recess on a main surface on which the phosphor is applied, and the light emitting element is embedded in the recess of the mounting member. Mounted, the main surface of the mounting member and the upper surface of the light-emitting element constitute a substantially flat coating surface by being provided in substantially the same plane, the phosphor has a specific gravity relative to each other. A semiconductor light emitting device comprising two or more different types of phosphors, which are applied to the application surface so as to have a constant thickness. 2. The semiconductor light emitting device according to claim 1, wherein the two or more kinds of phosphors are formed and laminated in layers for each kind. 3. The phosphor according to claim 1 or 2, wherein the phosphor is directly coated on the coating surface.
The semiconductor light-emitting device described.