JP3533345B2 - Semiconductor light emitting device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device,
In particular, it belongs to a semiconductor light emitting device that has high light extraction efficiency, is inexpensive, and is excellent in mass productivity.

[0002]

2. Description of the Related Art When light emitted from an arbitrary point of a light transmissive material A reaches a boundary surface between the light transmissive material A and a light transmissive material B adjacent to the light transmissive material A, the path of the light changes at the boundary surface. The refraction phenomenon is known. In FIG. 9 showing a schematic diagram of refraction of light,
The angle formed by the light traveling through the light-transmitting substance A with the normal line of the boundary surface is the incident angle θ ₁ , and the angle formed by the light entering the light-transmitting substance B with the normal line of the boundary surface is the refraction angle θ ₂ , the light transmitting property. n ₁ the refractive index of the material a, and the refractive index of the light transmitting material B and n _2, theta ₁ according to the law of refraction (Snell's law), the relationship between theta _2, n _1, n ₂ is represented by the following formula Be done. sin θ ₁ / sin θ ₂ = n ₂ / n ₁ (1)

N₂<N₁, The incident angle θ₁Is gradually larger
Then, as shown in FIG.₁= Θ_cso
Refraction angle θ₂= Π / 2, which is the critical angle of incidence
θ_cThen, light is transmitted from the light-transmitting substance A to the light-transmitting substance B.
Instead, it is totally reflected at the boundary surface. Θ in equation (1)₁= Θ_c, Θ₂
= Π / 2, the critical angle θ_cIs given by the following equation.           sin θ_c= N₂/ N₁           θ_c= Sin^-1(n₂/ N₁) (2)

A radiant flux Φ of light emitted from an arbitrary light emitting point p (point light source) in the light-transmitting substance A is expressed by the following equation by the radiant intensity I of the radiated light and the solid angle ω formed by the radiated light. It Φ = ∫Idω (3) Here, if the radiation intensity I is constant in all directions, Φ = I∫dω (3) ′ Further, the solid angle ω formed by the radiated light has p as its apex. Apex angle 2
Since it is considered to be the solid angle of the cone of θ, ω = 2π (1-cosθ) (4) Therefore, the radiant flux Φ is expressed by the following equation. Φ = 2πI (1-cosθ) (5)

The radiant flux generated in the light transmissive substance A is represented by Φ₁When
Then Φ₁Radiates uniformly over the entire circumference of the emission point p
Therefore, by substituting θ = π into equation (5),           Φ₁= 4πI (6) On the other hand, light is not totally reflected at the interface between the light-transmitting substances A and B
The radiant flux transmitted from the transparent substance A to the light transparent substance B
Φ₂Then, Φ₂Is the apex angle 2θ_cIs the radiant flux within the cone of
Therefore, θ = θ_cSubstituting into equation (5),           Φ₂= 2πI (1-cosθ_c) (7) Therefore, the radiant flux Φ generated in the light transmissive material A₁Is translucent
Radiant flux Φ transmitted to transient substance B₂The ratio, that is,
The light extraction efficiency η is           η = Φ₂/ Φ₁           η = (1-cos θ_c) / 2 (8)

Based on the above discussion of the optical model, a conventional semiconductor light emitting device will be described below. FIG. 11 shows a conventional semiconductor light emitting device having a hermetic seal structure. This semiconductor light-emitting device, a metal stem (20), the metal stem (20) in a state of penetrating the stem (20) and electrically insulated from the stem (20) by a sealing glass (19). A fixed metal post (21) and a first electrode (5) and a second electrode (6) on the upper and lower surfaces, respectively, and the second electrode (6) on the metal stem (20) A semiconductor light emitting element (4) bonded with a conductive adhesive (7), a bonding wire (8) connecting the first electrode (5) of the semiconductor light emitting element (4) and the post (21), It has a glass window (23) on the top and a metal cap (22) adhered to the stem (20) by welding or other method. Stem (20) and cap (2
The space surrounding the semiconductor light emitting element (4) sealed with 2) is filled with a sealing gas (24) such as air or an inert gas.

[0007]

Considering the refraction phenomenon of the semiconductor light emitting device of the hermetically sealed structure, the semiconductor light emitting element (4) corresponds to the light transmissive substance A, and the sealing gas (24) is light transmissive. Corresponds to substance B. For example, SiC, GaAs, GaP, Ga
Various compound semiconductors such as AsP, GaAlAs, InAlGaP, InGaN, and GaN are generally used for the semiconductor light emitting device (4), but most of these compound semiconductors have a refractive index of 3.2 to 3. It will be as high as 7. On the other hand, since the refractive index of the sealing gas (24) such as air is about 1.0, the critical angle θ _{c at} the interface between the two is extremely small.

Therefore, a hermetically sealed structure type semiconductor
In body light emitting device, made inside semiconductor light emitting element (4)
Most of the light is reflected at the interface with the sealing gas (24) and the luminous efficiency is improved.
Has the drawback of decreasing. In addition, GaAs, GaAsP, GaAlAs, etc.
Since the light transmittance of the crystal is low, a large amount of light reflected at the interface
The part is re-absorbed internally, resulting in extremely high light extraction efficiency.
Bad. For example, since the refractive index of GaAsP is about 3.6,
From equation (2), the critical angle θ _cIs about 16 degrees, and according to equation (8) R
> The light extraction efficiency η is only about 2%.

The hermetically sealed semiconductor light emitting device had a mainstream structure in the early stages of development of the semiconductor light emitting device. However, the package is expensive, the productivity is low, and the semiconductor light emitting device (4) having a high refractive index is used. A sealing gas with a low refractive index (2
4) and the sealing gas (2) to fill the semiconductor light emitting device (4).
Since the total reflection at the interface with 4) is large and the light extraction efficiency of the semiconductor light emitting device is extremely low, it is currently used only in limited applications. Therefore, various studies have been conducted to date in order to improve the defect that the conventional semiconductor light emitting device has a low light extraction efficiency.

[0010]

[Table 1]

12 and 13 are proposed by Kerr (WNCarr) in a paper (Infrared Physics, Vol.6, p.1-19 (1966)), and the optical structure of the semiconductor light emitting device (4) is shown. An example of a curved surface type semiconductor light emitting device in which the light extraction efficiency is improved by devising the above will be shown. Car, Weierstrass trunca
radiant flux, radiant intensity, and radiance when GaAs light-emitting elements were formed in various shapes such as hemispheres such as rotations, truncated ellipses, truncated cones, and parabolas. Table 1 showing the Kerr calculation results shows that a normal hexahedral semiconductor light emitting device is used.
The radiant flux of (4) is 0.013, whereas the radiant flux of a wire-strass sphere or parabolic semiconductor element (4) is about 30.
Since the value is about 0.34, which is almost doubled, a very high light extraction efficiency can be obtained in the curved semiconductor light emitting device.

By the way, when the semiconductor light emitting device (4) is generally manufactured, a semiconductor wafer in which a large number of light emitting devices are formed at regular intervals is cut into a lattice shape, and a large number of hexahedron-shaped minute light emission is performed at a time. The elements are separated. This method is excellent in mass productivity and can manufacture an inexpensive semiconductor light emitting device.

However, when manufacturing a curved surface type semiconductor light emitting device, the minute semiconductor light emitting element (4) must be processed into a special shape by mechanical polishing, chemical etching or the like. ) Is often hard and brittle, and crystal defects such as dislocations may occur in the semiconductor crystal due to mechanical shock and strain during processing, and there is a risk that the luminous efficiency of the semiconductor light emitting device (4) will decrease. There is. Further, if the surface of the semiconductor light emitting device (4) is contaminated during processing, there arises a problem that the luminous efficiency is reduced. Therefore, the semiconductor light emitting device (4) requires careful and precise processing, and cannot be mass-produced inexpensively like the hexahedral semiconductor light emitting device (4).

As described above, in the curved surface type semiconductor light emitting device, a high light extraction efficiency of the semiconductor light emitting element (4) can be obtained, but the minute semiconductor light emitting element (4) has a special shape while preventing crystal defects and contamination. Since it has to be processed, there is a problem of poor mass productivity, and since an inexpensive semiconductor light emitting device cannot be manufactured,
It can only be used in extremely limited applications such as high power light emitting diode devices for optical communication.

FIG. 14 shows, for example, CJNuese.
Et al. (J. Electrochem. Soc. Vol. 116, No. 2, p. 248 (196
The resin-encapsulated semiconductor light emitting device described in 9)) is shown.
This semiconductor light emitting device comprises a pair of wiring conductors (2, 3), a first electrode (5) on the upper surface and a second electrode (6) on the lower surface, and the second electrode (6) is conductive. A pair of wiring conductors via adhesive (7)
Semiconductor light-emitting device (4) adhered to one end of (2, 3) (2)
A bonding wire (8) for connecting the first electrode (5) of the semiconductor light emitting element (4) and the other end (3) of the pair of wiring conductors (2, 3), and the semiconductor light emitting element (4) ), Bonding wire
(8), and a transparent hemispherical sealing resin (14) for sealing the ends of the pair of wiring conductors (2, 3). Semiconductor light emitting element
The light extraction efficiency can be improved by sealing the periphery of (4) with a semi-spherical transparent sealing resin (14).

When considering the light extraction efficiency of the resin-sealed semiconductor light emitting device, total reflection at the interface between the semiconductor light emitting element (4) and the sealing resin (14), and the sealing resin (14) and the outside Total reflection at the interface with air must be considered. However, with respect to the length of one side of the semiconductor light emitting element (4), the sealing resin (1
If the diameter of the hemisphere of 4) is sufficiently large, the semiconductor light emitting element (4) can be regarded as a point light source with respect to the sealing resin (14),
If the semiconductor light emitting element (4) is placed at the focal point (center point) of the hemispherical sealing resin (14), the light emitted from the semiconductor light emitting element (4) and transmitted through the sealing resin (14) will be sealed. Even if the critical angle at the interface between the stop resin (14) and air is small, the light is incident perpendicularly to the interface, so total reflection does not occur. Therefore, regarding the light extraction efficiency of the resin-sealed semiconductor light emitting device, only total reflection at the interface between the semiconductor light emitting element (4) and the sealing resin (14) may be considered.

Here, similarly to the semiconductor light emitting device of the hermetically sealed structure shown in FIG. 11, the light extraction efficiency when the semiconductor light emitting element (4) is placed in _air is η _air , and the critical angle at that time is (θ _c ) When _air is used, formula (9) is obtained from formula (8). η _air = {1-cos (θ _c ) _air } / 2 (9) Further, the light extraction efficiency when the semiconductor light emitting device (4) is sealed with resin is η _dome , and the critical angle at that time is (θ _c ) If _dome , then equation (10) is obtained from equation (8). η _dome = {1-cos (θ _c ) _dome } / 2 (10) Therefore, the ratio, that is, the index of how many times the light extraction efficiency is increased by the hemispherical sealing resin (14) is expressed by the formula (10). Is divided by Equation (9), and is expressed by Equation (11). _{η dome / η air = {1} -cos (θ c) dome} / {1-cos (θ c) air} (11)

FIG. 15 shows that when GaAsP of the semiconductor light emitting device (4) has a refractive index of about 3.6, the refractive index of the sealing resin (14).
(n) It is a graph which shows the calculated value which calculated _| required (eta) _dome / (eta) _air value with respect to _dome from Formula (11). As can be understood from FIG. 15, in the resin-sealed semiconductor light emitting device, the sealing resin (1
The larger the refractive index of 4), the greater the light extraction efficiency can be improved.
In addition, the resin-sealed semiconductor light emitting device is generally widely produced at present because of its simple manufacturing method, excellent mass productivity, and low cost. However, in the resin-sealed semiconductor light emitting device, for example, the refractive index (n) _{dome of the} sealing resin (14) is
= 1.5, η _{d ome} / η _air is 2.3, the sealing resin
Since the refractive index of (14) is as low as about 1.5 regardless of the type, the light extraction efficiency cannot be significantly improved. As described above, with any of the conventional semiconductor light emitting devices, it has not been possible to manufacture a semiconductor light emitting device that is excellent in mass productivity, inexpensive, and excellent in light extraction efficiency by any method.

It is an object of the present invention to provide a semiconductor light emitting device having excellent light extraction efficiency. Another object of the present invention is to provide a semiconductor light emitting device which is excellent in mass productivity and can be manufactured at low cost. It is another object of the present invention to provide a semiconductor light emitting device in which at least a part of the light emitting portion of the semiconductor light emitting element is sealed with a transparent substance having a high refractive index.

[0020]

A semiconductor light emitting device according to the present invention comprises a pair of wiring conductors (2, 3) and a pair of wiring conductors (2, 3).
A plurality of electrodes (5,
Semiconductor light emitting device (4, 4 ') having 6), and semiconductor light emitting device
Internal light transmission layer (10) covering at least part of (4, 4 ')
And an external light transmission layer (11) that covers the semiconductor light emitting elements (4, 4 ′), the ends of the wiring conductors (2, 3) and the internal light transmission layer (10). The light emitted from the semiconductor light emitting device (4, 4 ') is emitted to the outside through the internal light transmission layer (10) and the external light transmission layer (11). The internal light transmission layer (10) is formed of polymetalloxane gel, and the internal light transmission layer (10) has a refractive index of 1.68.
It is a value of 5 or more and less than or equal to the refractive index of the semiconductor light emitting device (4, 4 ′). For example, the internal light transmission layer (10) is ZnO, TiO ₂ , Al ₂ O ₃ ,
It is formed of Y ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , ZrO ₂ or ZrO ₂ —SiO ₂ based oxide. The polymetalloxane gel is formed by subjecting a metal alkoxide or ultrafine particle metal oxide to a sol-gel method.

When considering the light extraction efficiency of the semiconductor light emitting device according to the present invention, total internal reflection at the interface between the semiconductor light emitting element (4, 4 ') and the internal light transmitting layer (10) and the internal light transmitting layer (10) are considered. ) And the external light transmission layer (11) at the interface, and the external light transmission layer (11)
And total external reflection at the interface with outside air must be considered.

In the present invention, the refractive index of the internal light transmitting layer (10) is substantially equal to the refractive index of the semiconductor light emitting device (4, 4 ').

When the refractive index of the semiconductor light emitting element (4, 4 ') is n ₁ and the refractive index of the internal light transmitting layer (10) is n ₂ , the refractive index n _{1 of the} semiconductor light emitting element (4, 4') is And the refractive index n of the internal light transmission layer (10)
_{When 2} is equal, the incident angle θ ₁ and the refractive index θ _{2 at} the interface between the semiconductor light emitting device (4, 4 ′) and the internal light transmitting layer (10) are equal to each other according to the formula (1), and incident light of any angle is obtained. Since refraction does not occur even with respect to it, the semiconductor light emitting element (4, 4 ′) and the internal light transmitting layer (10) can be handled as an optically integrated structure. Therefore, the semiconductor light emitting device (4, 4 ') and the internal light transmitting layer (1
Total reflection at the interface with (0) need not be considered.

Further, the inner light transmitting layer (10) and the outer light transmitting layer (1
Regarding the total reflection at the interface with 1) and the total reflection at the interface between the external light transmitting layer (11) and the external air, the internal light transmitting layer (10) is the semiconductor light emitting element of the curved semiconductor light emitting device. (4) is formed in the same hemispherical shape, and the external light transmission layer (11) is formed in the same hemispherical shape as the sealing resin (14) of the resin-encapsulated semiconductor light emitting device, and the internal light transmission layer ( The diameter of the external light transmitting layer (11) is made sufficiently larger than the diameter of 10), and the hemispherical internal light transmitting layer (1) is located at the focal point (center point) of the hemispherical external light transmitting layer (11).
If it is formed so that the focal points of
(4, 4 ') and the internal light transmission layer (10) can be regarded as a point light source for the external light transmission layer (11), and the semiconductor light emitting device (4, 4')
The light emitted from the internal light transmission layer (10) is transmitted perpendicularly to the interface between the internal light transmission layer (10) and the external light transmission layer (11). Total reflection does not occur even when the difference in refractive index from the light transmitting layer (11) is large and the critical angle is small. Similarly, total reflection does not occur at the interface between the external light transmission layer (11) and the external air.

Even when the refractive index of the internal light transmitting layer (10) is smaller than the refractive index of the semiconductor light emitting element (4, 4 '), the value close to the refractive index of the semiconductor light emitting element (4, 4') is as close as possible. If selected, the critical angle at the interface between the semiconductor light emitting device (4, 4 ′) and the internal light transmitting layer (10) becomes large, so that the total reflection amount can be reduced.

Therefore, in the present invention, the semiconductor light emitting device (4,
4 ') and the total reflection at the interface between the internal light transmission layer (10), and the total reflection at the interface between the internal light transmission layer (10) and the external light transmission layer (11),
It is possible to increase the light extraction efficiency by reducing the total reflection at the interface between the external light transmission layer (11) and the external air.

In the embodiment of the semiconductor light emitting device according to the present invention, the first electrode (5) is formed on the upper surface of the semiconductor light emitting element (4, 4 ′), and the second electrode (6) is formed on the lower surface, Second electrode
(6) is bonded to one end (2) of the pair of wiring conductors (2, 3) via a conductive adhesive (7), and the first electrode (5) is paired with a bonding wire (8). Is connected to the other end (3) of the wiring conductors (2, 3). The internal light transmitting layer (10) covers the entire side surface except the lower surface of the semiconductor light emitting element (4, 4 ′) or the upper surface of the semiconductor light emitting element (4, 4 ′).

In another embodiment of the semiconductor light emitting device according to the present invention, the semiconductor light emitting element (4, 4 ′) includes a pair of wiring conductors (2, 4 ′).
3) is mounted on one end (2) of the semiconductor light emitting element (4,
The electrodes (5, 6) of 4 ') are electrically connected to the ends of the pair of wiring conductors (2, 3) by bonding wires (8, 9). The semiconductor light emitting device (4, 4 ') is one of the pair of wiring conductors (2, 3) (2)
It is placed in the cup portion (2a) formed at the end of the. The internal light-transmitting layer (10) is formed in the cup part (2a), and the semiconductor light-emitting element (4, 4 ') is adhered onto the internal light-transmitting layer (10) or in the internal light-transmitting layer (10). Buried.

In another embodiment of the semiconductor light emitting device according to the present invention, the pair of wiring conductors (2, 3) are formed on the insulating substrate (12). Cup part (2a) on one main surface of insulating substrate (12)
Is formed, and the semiconductor light-emitting element (4,
4 ') are fixed and a pair of electrodes of the semiconductor light emitting device (4, 4')
(5, 6) are electrically connected to the pair of wiring conductors (2, 3) formed on one main surface of the insulating substrate (12). The semiconductor light emitting device (4, 4 ') is composed of a light-transmitting substrate (4a) and a semiconductor layer (4b to 4e) made of II-IV group or III-V group compound semiconductor, and the substrate (4a ) Has one main surface (4i) which constitutes a main light extraction surface and the other main surface (4j) on which the semiconductor layers (4b to 4e) are formed. The semiconductor layer (4b-4e) is an insulating substrate (1
2) is connected to a pair of external electrodes (5, 6) facing each other, and one main surface (4i) of the substrate (4a) is on the side opposite to the side facing the insulating substrate (12). Will be placed. The internal light transmission layer (10) is
The semiconductor light emitting element (4, 4 ′) is covered from the side surface except the lower surface to the entire upper surface, or the semiconductor light emitting element (4, 4 ′) is covered from the upper surface.

In addition, a fluorescent substance (10a) which is excited by the emission wavelength of the semiconductor light emitting device (4, 4 ') and emits light having a wavelength different from the emission wavelength of the semiconductor light emitting device (4, 4') is used as an internal light transmitting layer ( 10), for example, the fluorescent substance (10a) is applied to the inner surface of the cup portion (2a) provided at the end of one of the pair of wiring conductors (2, 3) (2). .

The external light transmission layer (11) has a Fresnel antireflection film formed on the interface in contact with the external atmosphere. Internal light transmission layer (1
A bonding film made of an inorganic / organic interface binder such as a silane coupling agent is formed at the interface between the (0) and the external light transmission layer (11).

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a semiconductor light emitting device according to the present invention applied to a semiconductor light emitting diode device will be described below with reference to FIGS.

As shown in FIG. 1, in the first embodiment of the semiconductor light emitting device (1) according to the present invention, a pair of wiring conductors (2,
3) and a semiconductor light emitting element (4) fixed to the flat end of one wiring conductor (2). The semiconductor light emitting element (4) has a pair of electrodes (5, 6), and the electrode (5) provided on the semiconductor light emitting element (4) is connected to the other wiring conductor ( It is electrically connected to 3). The electrode (6) provided on the bottom of the semiconductor light emitting element (4) is adhered to the end of one wiring conductor (2) via a conductive adhesive (7). The conductive adhesive (7) is a thermosetting organic resin paste made of a one-component epoxy resin or the like in which fine metal flakes such as gold and silver are mixed. The semiconductor light emitting element (4), the electrodes (5, 6) and one bonding wire (8) have an end portion formed in a substantially elongated spherical shape at the flat end portion of one wiring conductor (2). Covered by (10). The semiconductor light emitting element (4), the end portions of the wiring conductors (2, 3) and the internal light transmission layer (10) are covered with an external light transmission layer (11) which is a transparent sealing resin. Therefore, the internal light transmission layer
(10) covers at least a part of the light emitting portion of the semiconductor light emitting device (4), the light emitted from the semiconductor light emitting device (4), the internal light transmission layer (10) and the external light transmission layer (11) Is released to the outside.

As shown in FIG. 2, a semiconductor light emitting device (4) such as a light emitting diode chip is made of, for example, a gallium arsenide phosphide compound semiconductor and emits orange to red light of about 580 to 680 nm. The gallium arsenide phosphide semiconductor is a GaAs _(1-X) P _X (where 0 <x ≦ 1 Hereinafter referred to as GaAsP). In the embodiment shown in FIG. 2, the light emitting diode chip (4)
For example, the n-type semiconductor region (4c) made of GaAsP is formed on the substrate (4a) made of n-type GaAs by the well-known epitaxial growth method or high-pressure attachment. Further, the p-type semiconductor region (4e) made of GaAsP is formed on the n-type semiconductor region (4c) by the epitaxial growth method.

The substrate (4a), n-type semiconductor region (4c) and p-type semiconductor region (4e) form a semiconductor layer. p-type semiconductor region (4e)
The anode electrode (external electrode) (5) formed above is electrically connected to the p-type semiconductor region (4e). The cathode electrode (external electrode) (6) formed on the base body (4a) is electrically connected to the base body (4a). The semiconductor light emitting device (4) consists of SiC, GaAs, GaP, GaAsP, G formed by the epitaxial growth method.
Light emitting diode (LED), laser diode (L) having compound semiconductor layers such as aAlAs, InAlGaP, InGaN, and GaN
D), a super luminescence diode (SLD) may be used.

[0036] and the refractive index n ₂ of the refractive index n ₁ and internal light transmitting layer of the semiconductor light emitting element (4) (10) equals (n ₁ = n ₂₎ case, the refraction angle of the incident angle from the formula (1) Are the same (θ ₁ = θ ₂ ), so theoretically the semiconductor light emitting device (4) and the internal light transmission layer (10)
Refraction does not occur at the interface with and, and the semiconductor light emitting element (4) and the internal light transmitting layer (10) can be handled optically as an integrated structure.

The refractive index of the internal light-transmitting layer (10) having a light-transmitting property with respect to the light emitted from the semiconductor light emitting device (4) is substantially equal to or less than the refractive index of the semiconductor light emitting device (4). In value. For example, the refractive index of the internal light transmitting layer (10) is a value between the refractive index of the semiconductor light emitting element (4) and the refractive index of the external light transmitting layer (11). The refractive index of the internal light transmitting layer (10) is 1.5 to 3.
0. Table 2 shows various materials of the internal light transmission layer (10).
The oxides shown in Table 2 can be made from single metal alkoxides and the double oxides can be made from complex metal alkoxides.
Further, a ZrO ₂ —SiO ₂ -based oxide obtained from a composite metal alkoxide of silicon (Si) and zirconium (Zr) can also be used as the internal light transmitting layer (10).

[0038]

[Table 2]

The internal light transmitting layer (10) is a semiconductor light emitting device (4).
The entire periphery from the side surface to the upper surface except for the lower surface is covered or the upper surface of the semiconductor light emitting device (4) is covered. The internal light transmitting layer (10) is a polymetalloxane gel formed by subjecting a metal alkoxide to a sol-gel method or a polymetalloxane gel formed by subjecting an ultrafine metal oxide to a sol-gel method or a low It is a melting point glass. The polymetalloxane gel that constitutes the internal light transmission layer (10) is prepared by dispersing a metal alkoxide, which is one of the organometallic compounds, in a solvent such as alcohol, and adding water and a trace amount of the catalyst dropwise and mixing them for hydrolysis and condensation. Apply a liquid sol in which the minute polymer of the metal oxide, which is generated as a result of the reaction, is dispersed in the solvent to the target object, leave it in the air to solidify (gel), and then heat It is generated by curing. A metal alkoxide from which a polymetalloxane gel having a high refractive index can be obtained, for example, a single metal alkoxide of aluminum, titanium, zirconium, or the like, a composite metal alkoxide composed of a plurality of metal alkoxides, or a part of a functional group of the metal alkoxide is modified. An inorganic / organic composite in which an organic resin monomer is introduced can be used.

The polymetalloxane gel constituting the internal light transmission layer (10) is an ultrafine metal oxide produced by a flame hydrolysis method in which a mixed gas of metal chloride gas, hydrogen and oxygen is burned at high temperature. Is dispersed in a solvent such as alcohol, and the liquid sol produced by dropping and mixing water is applied to the object, left in the air to solidify (gel), and then heat-cured to produce It is also possible to do so. For example, a single ultra-fine particle metal oxide such as aluminum, titanium, zirconium or the like, or a composite ultra-fine particle metal oxide composed of a plurality of ultra-fine particle metal oxides, which can provide a polymetalloxane gel having a high refractive index. A particulate metal oxide can be used.

The internal light transmitting layer (10) can also be made of low melting point glass. When low-melting glass is used, the low-melting glass powder is mixed with an organic binder dissolved in a solvent, dried and solidified, and then heated and baked in air to burn and scatter the organic binder to melt the glass powder.

The material forming the internal light transmission layer (10) is a low melting glass powder mixed with a sol made of metal alkoxide or ultrafine metal oxide or an organic binder dissolved in a solvent, both of which are liquid. Is. Internal light transmission layer (1
The material forming 0) is generically called a light transmitting liquid material. Therefore, by devising the method of covering the semiconductor light emitting element (4) and the shape of the pair of wiring conductors (2, 3), the internal light transmitting layer (10) formed by solidifying the light transmitting liquid material is used as an optical layer. It can be formed in a desired shape that is advantageous in terms of its properties. Therefore, for example, in FIG.
Also, unlike the conventional semiconductor light emitting device shown in FIG. 13, a hexahedral semiconductor light emitting element that can be manufactured at low cost is used without forming the semiconductor light emitting element (4) itself into a special curved surface shape with high light extraction efficiency. Then, the same effect can be obtained.

For example, when the internal light transmission layer (10) is formed in a hemispherical shape, a light transmission liquid material is dropped on the semiconductor light emitting element (4) adhered to the end of one wiring conductor (2). Alternatively, the pair of wiring conductors (2, 3) are turned upside down and brought into contact with the light-transmitting liquid material filled in the container (pre-dip method).
Etc., after covering the periphery of the semiconductor light emitting element (4) with a light transmitting liquid material by any method, a pair of wiring conductors (2,
3) The light-transmitting liquid material may be solidified while the whole is installed in an inverted state (or an upright state). In this case, the internal light transmitting layer (10) can be formed in a desired hemispherical shape by appropriately controlling the balance of the light transmitting liquid material such as its own weight, viscosity and surface tension.

Although it is theoretically desirable that the refractive index of the internal light transmitting layer (10) is the same as or as close as possible to the semiconductor light emitting device (4), the refractive index of the semiconductor light emitting device (4) and the external light transmitting layer (10) are If the value is between the refractive index of 11), the total reflection at the interface between the semiconductor light-emitting device (4) and the internal light-transmitting layer (10) is considerably reduced. It is possible to improve the light extraction efficiency as compared with a static semiconductor light emitting device.

Even if the internal light transmitting layer (10) contains a fluorescent substance (10a) which is excited by the emission wavelength of the semiconductor light emitting device (4) and emits light having a wavelength different from the emission wavelength of the semiconductor light emitting device (4). Good. Alternatively, the fluorescent substance (10a) can be applied to the inner surface of the cup portion (2a) provided at the end of one of the pair of wiring conductors (2, 3) (2). Fluorescent substance (10a) is the internal light transmission layer (10)
The semiconductor light emitting device contained in or coated on the inner surface of the cup portion (2a) can be a semiconductor light emitting device that emits light having a wavelength different from the emission wavelength of the semiconductor light emitting element (4).

The external light transmitting layer (11) is a resin having a light transmitting property such as an epoxy resin, a silicone resin, a polyester resin or an acrylic resin, or a functional group of a metal alkoxide modified to introduce an organic resin monomer. It is made of an inorganic / organic composite polymer and is formed by a method such as potting or injection molding.

The internal light transmission layer (10) and the external light transmission layer (1
In some cases, peeling may occur at the interface with 1) and light may be reflected by the thin air layer formed at the interface, resulting in a decrease in light extraction efficiency. The inner light transmitting layer (10) and the outer light transmitting layer (11) are formed by forming a bonding film made of an inorganic / organic interface binder such as a silane coupling agent on the surface of the inner light transmitting layer (10).
The peeling at the interface with can be prevented. The silane coupling agent is an organometallic compound having a functional group that binds to an inorganic substance and a functional group that reacts and binds to an organic substance, and has a function of binding the organic substance and the inorganic substance by interposing itself. If this is diluted with an appropriate solvent such as alcohol or water and applied thinly on the surface of the internal light-transmitting layer (10) and dried to form the external light-transmitting layer (11), a bond consisting of a silane coupling agent is formed. Internal light transmission layer (10) and external light transmission layer (11) through the film
Since the and are strongly bonded to each other to prevent peeling, the light extraction efficiency does not decrease.

FIG. 3 shows a second embodiment of the semiconductor light emitting device according to the present invention. An internal light transmission layer (10) is formed in the cup portion (2a) formed at the end of one wiring conductor (2), and the semiconductor light emitting element (4 ') is formed on the internal light transmission layer (10). It is bonded via a light-transmissive adhesive (7). Light-transmissive adhesive
(7) is a paste prepared by mixing a light-transmitting ceramic powder with a thermosetting organic resin such as a one-pack type epoxy resin, or an inorganic adhesive using a metal alkoxide or ultrafine particulate metal oxide as a starting material. The first electrode (5) formed on the upper surface of the semiconductor light emitting device (4 ') is connected to the end of the other wiring conductor (3) by the bonding wire (8), and the second electrode
(6) is one wiring conductor by the bonding wire (9)
It is glued to the end of (2). Bonding Wire (8, 9)
Is a fine metal wire made of gold, silver, aluminum, copper, or the like.

As shown in FIG. 4, the semiconductor light emitting device (4 ') such as a light emitting diode chip is made of, for example, a gallium nitride compound semiconductor, and emits blue light of, for example, about 440 to 470 nm. The gallium nitride-based semiconductor is an In _(1-X) Ga _X N (formed by a well-known epitaxial growth method or the like on a substrate (4a) made of a semiconductor substrate such as Si, GaAs, SiC, GaP or a ceramic substrate such as sapphire ( However, 0 <x ≦ 1. Below, InGaN
Is described). In the embodiment shown in FIG. 4, the light emitting diode chip (4 ′) is made of, for example, a well-known epitaxial growth method, and a buffer layer (made of GaN on a substrate (4a) made of sapphire and made of GaN is formed on a substrate (4a) made of sapphire having light transmittance). 4b) is formed, and the n-type semiconductor region (4c) is formed on the buffer layer (4b) by the gallium nitride based semiconductor made of GaN. By the epitaxial growth method,
The active layer (4
d) is formed on the n-type semiconductor region (4c). A p-type semiconductor region (4e) is formed on the active layer (4d).

The buffer layer (4b), the n-type semiconductor region (4c), the active layer (4d) and the p-type semiconductor region (4e) form a semiconductor layer. An anode electrode (external electrode) (5) formed on the p-type semiconductor region (4e) is electrically connected to the p-type semiconductor region (4e). A cathode electrode (external electrode) (6) formed on the n-type semiconductor region (4c) is electrically connected to the n-type semiconductor region (4c).

In order to form the internal light transmitting layer (10) in a parabolic shape, a parabolic cup portion (2a) is provided at one end (2) of the pair of wiring conductors (2, 3) and the cup portion is formed. A light-transmitting liquid material is injected and solidified in (2a) to form an internal light-transmitting layer (10), and then the semiconductor light-emitting element (4 ') is bonded with a light-transmitting adhesive (7) and sealed with a light-transmitting resin. Then, the external light transmitting layer (11) is formed.
At this time, after adhering with a light-transmissive adhesive (7), a light-transmissive liquid material is further injected and solidified, and the semiconductor light-emitting element (4 ')
May be embedded in the internal light transmitting layer (10).

Further, in order to form the internal light transmitting layer (10) in the shape of a truncated cone, one end (2) of the pair of wiring conductors (2, 3) is formed into a truncated cone shape. A molded cup portion (2a) is provided, and the semiconductor light emitting device (4 ') is bonded to the bottom of the cup portion (2a) with a conductive adhesive (7) or a light transmissive adhesive (7) to form a light transmissive liquid material. Is injected and solidified to form an internal light transmitting layer (10). At this time, the semiconductor light emitting element (4 ') is adhered after the light transmitting liquid material is injected and solidified to some extent in advance, and the light transmitting liquid material is added thereto to form the internal light transmitting layer (10). The position of the semiconductor light emitting device (4 ′) in the internal light transmission layer (10) can be adjusted.

A Fresnel antireflection film may be formed on the interface where the external light transmission layer (11) contacts the external atmosphere. When a Fresnel antireflection film is formed, an external light transmission layer (11)
The Fresnel reflection generated at the interface between air and air can be reduced, and the light extraction efficiency of the semiconductor light emitting device (1) can be further improved.

FIG. 5 shows a third embodiment of the present invention applied to a chip type light emitting diode device (1) using an insulating substrate. The chip type light emitting diode device (1) is
Insulating substrate (12) with cup (2a) formed on one main surface
A first wiring conductor (2) and a second wiring conductor (3) formed on the insulating substrate (12) so as to be separated from each other, and a first wiring conductor
The light emitting diode chip (4 ') fixed to the bottom surface of the cup portion (2a) of (2) via a light transmissive adhesive (7), the anode electrode (5) of the light emitting diode chip (4') and A second bonding wire (9) for electrically connecting the second wiring conductor (3),
The first bonding wire (8) for electrically connecting the cathode electrode (6) of the light emitting diode chip (4) and the first wiring conductor (2), and the light emitting diode chip filled in the cup portion (2a) (4 '), the anode electrode (5), the cathode electrode (6), the anode electrode (5) and the internal light transmitting layer (9) that covers the ends of the bonding wires (8, 9) connected to the cathode electrode (6) ( Ten)
And an external light transmitting layer having a trapezoidal cross section formed on one main surface of the insulating substrate (12) and covering the outside of the internal light transmitting layer (10).
(11) and are provided. Inner light transmitting layer (10) is cup part (2a)
It swells upward from and is formed into a curved surface. One ends of the first wiring conductor (2) and the second wiring conductor (3) are arranged in the cup portion (2a). The light emitting diode chip (4 ') is fixed to the first wiring conductor (2) at the bottom portion (2b) of the cup portion (2a) via a light transmissive adhesive (7). First wiring conductor (2)
And the other end of each of the second wiring conductors (3) is an insulating substrate.
It is arranged so as to extend to the side surface of (12) and the other main surface. The internal light transmitting layer (10) projects in a hemispherical shape from the upper end portion (2d) of the cup portion (2a). The internal light transmitting layer (10) is further sealed by the external light transmitting layer (11), and the light emitted from the semiconductor light emitting element (2) is
After passing through the internal light transmission layer (10), it is emitted to the outside of the external light transmission layer (11).

When the fluorescent substance (10a) is mixed in the internal light transmitting layer (10), the light emitted from the semiconductor light emitting device (4 ') reaches the internal light transmitting layer (10), and a part of the light is emitted from the internal light transmitting layer (10). The external light transmission layer (11) is converted to a different wavelength in the transmission layer (10) and mixed with a light component from the semiconductor light emitting element (2) which is not wavelength-converted.
Is released to the outside through. For example, about 365 nm to 40
A GaN-based light emitting diode chip (4 ') that emits ultraviolet rays having an emission peak wavelength of 0 nm, and an excitation peak wavelength of about 360
, a green light-emitting diode device having a very sharp emission distribution with a half-value width of about 12 nm when using a fluorescent substance (10a) of Ga and Tb (terbium) activated Y ₂ SiO _{5 having} an emission peak wavelength of about 543 nm ( 1) is obtained. A light-absorbing substance (10c) that absorbs a specific emission wavelength, a light-scattering substance (10b) that scatters light emitted from the semiconductor light-emitting element (4 '), or a binder (10b) that prevents cracks in the internal light-transmitting layer (10). May be incorporated in the internal light transmitting layer (10). Also in the light emitting diode device (1) of FIG. 5, the light extraction efficiency is improved by the internal light transmitting layer (10) having a high refractive index.

In the case of manufacturing a semiconductor light emitting device having an insulating substrate (12), after forming the cup portion (2a) on one main surface of the insulating substrate (12), the insulating substrate (12) is formed. A pair of wiring conductors (2, 3) extending in opposite directions along one main surface is formed, and then one of the pair of wiring conductors (2, 3) is formed at the bottom portion (2b) of the cup portion (2a). The semiconductor light emitting element (2) is fixed to the.

FIG. 6 shows a fourth embodiment according to the present invention in which a light emitting diode chip having bump electrodes (protruding electrodes) is applied to the chip type light emitting diode device (1) shown in FIG. As shown in FIG. 7, the light emitting diode chip (4) has a structure in which the semiconductor light emitting device (4 ′) shown in FIG. 4 is inverted, and the anode electrode (5) and the cathode electrode (6) are respectively formed by wiring conductors ( It is formed as a bump electrode directly fixed to 2, 3). FIG. 8 shows a fifth embodiment in which a light emitting diode chip having bump electrodes is directly fixed to an external lead type wiring conductor (2, 3). In the embodiment of FIGS. 6 and 8, the bonding wire can be omitted.

The internal light transmitting layer (10) has the following excellent characteristics. [1] The semiconductor light emitting device (4,
It is possible to efficiently extract light from 4 ') and realize a semiconductor light emitting device (1) having a large light output. [2] Since a large light extraction efficiency can be obtained with an inexpensive hexahedral semiconductor light emitting element (4, 4 ′) without using an expensive curved semiconductor light emitting element, a semiconductor light emitting device with a large light output and a low cost ( 1) can be realized. [3] Since the internal light-transmitting layer (10) is formed of a light-transmitting liquid material, the internal light-transmitting layer having various optically advantageous shapes is formed.
(10) can be realized. [4] Since the semiconductor light emitting device (4) is doubly covered with the internal light transmitting layer (10) and the external light transmitting layer (11), the semiconductor light emitting device (1) having excellent environmental resistance can be realized. [5] A fluorescent substance that is excited at the emission wavelength of the semiconductor light emitting device (4) inside the internal light transmission layer (10) or on the inner surface of the cup portion (2a)
By mixing or coating (10a), a semiconductor light emitting device (1) that emits light having a wavelength different from that of the semiconductor light emitting element (4, 4 ′) can be realized.

[0059]

As described above, in the semiconductor light emitting device according to the present invention, a semiconductor light emitting device having high light extraction efficiency and high reliability can be obtained without depending on the shape of the semiconductor light emitting element. Also,
This semiconductor light emitting device is excellent in mass productivity and can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a semiconductor light emitting device according to the present invention.

FIG. 2 is a sectional view of a semiconductor light emitting element used in the semiconductor light emitting device shown in FIG.

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

4 is a cross-sectional view of a semiconductor light emitting element used in the semiconductor light emitting device shown in FIG.

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

FIG. 6 is a sectional view of a semiconductor light emitting device according to a fourth embodiment of the present invention.

7 is a cross-sectional view of a semiconductor light emitting element used in the semiconductor light emitting device shown in FIG.

FIG. 8 is a sectional view of a semiconductor light emitting device according to a fifth embodiment of the present invention.

FIG. 9 is a principle diagram showing a refraction state of light.

FIG. 10: Principle diagram showing the critical angle of light

FIG. 11 is a sectional view of a conventional semiconductor light emitting device having a hermetic seal structure.

FIG. 12 is a perspective view showing a conventional curved semiconductor light emitting device.

FIG. 13 is a cross-sectional view showing a conventional curved semiconductor light emitting device.

FIG. 14 is a cross-sectional view showing a conventional resin-sealed semiconductor light emitting device.

FIG. 15 is a graph showing η _dome / η _air value with respect to refractive index.

[Explanation of symbols]

(1) ・ ・ Semiconductor light-emitting device, (2, 3) ・ ・ Wiring conductor, (2
a) ・ ・ Cup part, (4,4 ') ・ ・ Semiconductor light emitting device, (4a)
..Substrate, (4b to 4e) .. Semiconductor layer, (5, 6) .. Electrode, (7) .. Conductive adhesive or light transmissive adhesive, (8,
9) ・ ・ Bonding wire, (10) ・ ・ Internal light transmitting layer, (11) ・ ・ External light transmitting layer, (12) ・ ・ Insulating substrate,
(14) ・ ・ Sealing resin, (19) ・ ・ Sealing glass, (20) ・
・ Metal stem, (21) ・ ・ Metal post, (22) ・ ・ Metal cap, (23) ・ ・ Glass window, (24) ・ ・ Sealing gas, (10a) ・ ・ Fluorescent substance, (10b) ..Light-scattering substances or binders, (10c) .. Light-absorbing substances,

Continued front page       (56) References JP-A-62-22491 (JP, A)                 JP-A-8-313742 (JP, A)                 JP-A-8-102553 (JP, A)                 Japanese Patent Laid-Open No. 10-65221 (JP, A)                 JP-A-10-242513 (JP, A)                 JP-A-50-20683 (JP, A)                 JP-A-11-163417 (JP, A)                 JP-A-5-3371 (JP, A)                 JP-A-6-82600 (JP, A)                 JP-A-1-283883 (JP, A)                 JP-A-7-235696 (JP, A)                 Actual Kaihei 4-63162 (JP, U)                 Japanese Patent Publication Sho 49-47993 (JP, B1)

Claims (14)

(57) [Claims] 1. A semiconductor light emitting element having a pair of wiring conductors, a plurality of electrodes electrically connected to the pair of wiring conductors, and an internal light covering at least a part of a light emitting portion of the semiconductor light emitting element. A transparent layer, the semiconductor light emitting device,
An external light transmission layer covering the end of the wiring conductor and the internal light transmission layer is provided, and the light emitted from the semiconductor light emitting element is emitted to the outside through the internal light transmission layer and the external light transmission layer. In the semiconductor light emitting device, the internal light transmissive layer is formed of polymetalloxane gel, and the refractive index of the internal light transmissive layer is 1.685 or more and less than or equal to the refractive index of the semiconductor light emitting element. Semiconductor light emitting device. 2. The internal light transmission layer is made of ZnO, TiO ₂ , Al
The semiconductor light emitting device according to claim 1, which is formed of ₂ O ₃ , Y ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , ZrO ₂ or ZrO ₂ —SiO ₂ based oxide. 3. The semiconductor light emitting device according to claim 1, wherein the polymetalloxane gel is formed by subjecting a metal alkoxide or ultrafine particle metal oxide to a sol-gel method. 4. The semiconductor light emitting device according to claim 1, wherein a refractive index of the internal light transmitting layer is substantially equal to a refractive index of the semiconductor light emitting element. 5. The refractive index of the internal light transmitting layer is 1.685.
5. The semiconductor light emitting device according to claim 4, wherein 6. The semiconductor light emitting device is mounted in a cup portion formed at one end of the pair of wiring conductors,
The semiconductor light emitting device according to claim 1, wherein the internal light transmitting layer is formed in the cup portion, and the semiconductor light emitting element is adhered onto the internal light transmitting layer or embedded in the internal light transmitting layer. 7. A first electrode is formed on an upper surface of the semiconductor light emitting element and a second electrode is formed on a lower surface of the semiconductor light emitting element, the second electrode being one of a pair of the wiring conductors via a conductive adhesive. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is bonded to an end portion, and the first electrode is connected to the other end portion of the pair of wiring conductors by the bonding wire. 8. A fluorescent substance that is excited by an emission wavelength of the semiconductor light emitting element and emits light having a wavelength different from the emission wavelength of the semiconductor light emitting element is mixed in the internal light transmitting layer, and the semiconductor light emitting element has a wavelength of 365 to 400 nm. Generating light having wavelengths of 440 to 470 nm and 580 to 680 nm.
The semiconductor light-emitting device according to any one of items 1 to 7. 9. The semiconductor light emitting device according to claim 8, wherein the fluorescent substance is applied to an inner surface of the cup portion provided at one end of the pair of wiring conductors. 10. A Fresnel antireflection film is formed on an interface of the external light transmitting layer, which is in contact with an external atmosphere.
The semiconductor light-emitting device according to any one of 1. 11. The bonding film made of an inorganic / organic interfacial binder such as a silane coupling agent is formed at the interface between the inner light transmitting layer and the outer light transmitting layer. The semiconductor light-emitting device according to. 12. The semiconductor light emitting device according to claim 1, wherein the pair of electrodes formed on the bottom of the semiconductor light emitting element are electrically connected to the pair of wiring conductors formed on the insulating substrate. 13. The semiconductor light emitting device comprises a light-transmissive base and a semiconductor layer made of a II-IV group or III-V group compound semiconductor, and the base constitutes a main light extraction surface. A main surface of the substrate, and the other main surface on which the semiconductor layer is formed, the semiconductor layer being arranged to face the insulating substrate and connected to the pair of external electrodes. 13. The semiconductor light emitting device according to claim 12, wherein the main surface is arranged on the side opposite to the side facing the insulating substrate. 14. The external light transmitting layer comprises a light transmitting epoxy resin, a silicone resin, a polyester resin,
14. The semiconductor light emitting device according to claim 1, comprising an organic resin such as an acrylic resin or an inorganic-organic composite polymer in which a functional group of a metal alkoxide is partially modified to introduce an organic resin monomer.