KR102170217B1 - Light emitting device - Google Patents

Abstract

Examples include a substrate; A light emitting structure disposed on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; And a first electrode and a second electrode respectively disposed on the first conductive type semiconductor layer and the second conductive type semiconductor layer, and a light emitting device having a plurality of grooves formed on a bottom surface of the substrate is provided.

Description

Light emitting device {LIGHT EMITTING DEVICE}

The embodiment relates to a light emitting device.

Group 3-5 compound semiconductors such as GaN and AlGaN are widely used in optoelectronics and electronic devices due to their many advantages, such as having a wide and easily adjustable band gap energy.

In particular, light emitting devices such as light emitting diodes and laser diodes using a group 3-5 or group 2-6 compound semiconductor material of semiconductors are developed in thin film growth technology and device materials, such as red, green, blue and ultraviolet rays. Various colors can be implemented, and efficient white light can be realized by using fluorescent materials or by combining colors. Low power consumption, semi-permanent life, quick response speed, safety, and environment compared to conventional light sources such as fluorescent lamps and incandescent lamps. It has the advantage of affinity.

Therefore, a light emitting diode backlight that replaces the cold cathode fluorescent lamp (CCFL) that constitutes the transmission module of the optical communication means, the backlight of the LCD (Liquid Crystal Display) display, and white light that can replace fluorescent or incandescent bulbs. Applications are expanding to diode lighting devices, automobile headlights and traffic lights.

In the light emitting device, a light emitting structure including a first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer is formed on a substrate made of sapphire, etc., and is formed on the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer, respectively. The first electrode and the second electrode are disposed. In the light emitting device, electrons injected through the first conductivity type semiconductor layer and holes injected through the second conductivity type semiconductor layer meet each other to emit light having energy determined by an energy band inherent to a material constituting the active layer. Light emitted from the active layer may vary depending on the composition of the material constituting the active layer, and may be blue light, ultraviolet light (UV), or deep ultraviolet light.

Light in the first wavelength region emitted from the light emitting device excites the phosphor, and light in the second wavelength region may be emitted from the phosphor. The phosphor may be included in a molding portion surrounding the light emitting device or may be disposed in the form of a phosphor film.

1 is a view showing a conventional light emitting device package.

In the light emitting device package, a light emitting device (chip) is electrically connected to the first lead frame 121 and the second lead frame 122 and the wire 140 on the bottom surface of the cavity of the package body 110 having the cavity and is disposed. Then, the molding part 150 including the phosphor 160 is filled in the cavity.

In the light-emitting device package illustrated in FIG. 1, the frequency at which the phosphor 160 is deposited in the cavity and light emitted from the light-emitting device (chip) is transmitted to the phosphor 160 is different for each area, so that color temperature variation may increase.

2 is a view showing a conventional light emitting device. In order to reduce the color temperature deviation, as shown in FIG. 2, a phosphor film may be disposed on a light emitting device (chip), and at this time, the electrode (pad) may be exposed to the outside of the phosphor film.

However, the light emitted to the side in the vertical light emitting device of FIG. 2 may not reach the phosphor film, and the color temperature deviation between the light emitted to the side and the light emitted toward the upper phosphor layer may increase.

The embodiment aims to reduce color temperature variation in a light emitting device or a light emitting device package.

Examples include a substrate; A light emitting structure disposed on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; And a first electrode and a second electrode respectively disposed on the first conductive type semiconductor layer and the second conductive type semiconductor layer, and a light emitting device having a plurality of grooves formed on a bottom surface of the substrate is provided.

The light emitting device may further include a side surface of the substrate and a phosphor layer disposed on the side surface and upper surface of the light emitting structure.

The plurality of grooves may have a depth of 1/10 to 3/10 of the size of the phosphor in the phosphor layer.

The plurality of grooves may have a depth of 1 micrometer to 3 micrometers.

The plurality of grooves may be formed by friction between the phosphor in the phosphor layer and the substrate.

The plurality of grooves may be arranged in a stripe shape or a concentric circle shape.

The size of the phosphor adjacent to the bottom surface of the substrate in the phosphor layer may be smaller than the size of the phosphor layer spaced apart from the bottom surface of the substrate.

The first electrode and the second electrode may protrude outside the phosphor layer.

In the light emitting device according to the embodiment, a phosphor layer surrounds the side and upper surfaces of the light emitting device, so that light in the first wavelength region emitted from the horizontal light emitting device in the upper direction and the side direction excites the phosphor in the phosphor layer, As light is emitted, the color temperature deviation of the light may be reduced in all areas.

1 is a view showing a conventional light emitting device package,
2 is a view showing a conventional light emitting device,
3A to 3I are views showing an embodiment of a manufacturing process of a light emitting device,
4A and 4B are views showing examples of a process of applying the phosphor layer of FIG. 3C,
5 is a view showing an embodiment of a light emitting device package in which a light emitting device manufactured by the above-described process is disposed.

Hereinafter, embodiments of the present invention capable of realizing the above object will be described with reference to the accompanying drawings.

In the description of the embodiment according to the present invention, in the case where it is described as being formed in "on or under" of each element, the upper (upper) or lower (lower) (on or under) includes both elements in direct contact with each other or in which one or more other elements are indirectly formed between the two elements. In addition, when expressed as "on or under", it may include not only an upward direction but also a downward direction based on one element.

3A to 3H are views showing an embodiment of a manufacturing process of a light emitting device.

As shown in FIG. 3A, a plurality of light emitting devices 200 are disposed on the sheet 310.

The sheet 310 may be made of a base film 310a, an adhesive 310b, and a protective film 310c as shown in FIG. 3B, and the adhesive 310b is made of a silicone adhesive, and a protective film The 310c may be removed prior to placing the light emitting device 200 on the adhesive 310b.

The adhesive 310b has excellent fixing power of a light emitting device in a process to be described later, has no deformation due to the heat resistance of silicon, and may not leave a residue when separated into each light emitting device. For this function, the silicone in the adhesive 310b may be mixed with trimethylated silica, poly-dimethyl siloxane, and poly ethylene terephtalate in a weight ratio of 10% to 60% to 30%, respectively.

The adhesive 310b serves to fix the light emitting device 200 to the sheet 310, but must be easily separated in a separation process described later, and has excellent elasticity, so that the light emitting device 200 as shown in FIG. 3C A portion of the electrodes 252 and 256 of) may be inserted.

FIG. 3C is a detailed diagram illustrating area'A' of FIG. 3A.

The light emitting device 200 is a horizontal light emitting device, the first electrode 252 and the second electrode 256 are disposed toward the sheet 310, and the first electrode 252 and the second electrode 256 Since at least a portion of is inserted into the sheet 310 and disposed, the upper portions of the first electrode 252 and the second electrode 256 are exposed in a process of applying the phosphor layer to be described later to secure an area for wire bonding.

The light emitting device 200 includes a substrate 210, a buffer layer 215, a light emitting structure 220, a light-transmitting conductive layer 240, a first electrode 252 and a second electrode 256.

The substrate 210 may be formed of a material suitable for growth of semiconductor materials or a carrier wafer, may be formed of a material having excellent thermal conductivity, and may include a conductive substrate or an insulating substrate. For example, at least one of sapphire (Al ₂ O ₃ ), SiO ₂ , SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, Ga ₂ 0 ₃ may be used.

When the substrate 210 is formed of sapphire, etc., and the light emitting structure 220 including GaN or AlGaN is disposed on the substrate 210, the lattice mismatch between GaN or AlGaN and sapphire is very large. Since the difference in the coefficient of thermal expansion between them is also very large, dislocation, melt-back, crack, pit, and surface morphology defects that deteriorate crystallinity occur. Therefore, the buffer layer 215 may be formed of AlN or the like.

A pattern may be formed on the surface of the substrate 210 as shown, and light emitted from the light emitting structure 220 and traveling to the substrate 210 may be refracted.

The light emitting structure 220 may include a first conductivity type semiconductor layer 222, an active layer 224 and a second conductivity type semiconductor layer 226.

The first conductivity type semiconductor layer 222 may be implemented as a compound semiconductor such as group III-V or group II-VI, and may be doped with a first conductivity type dopant. The first conductivity type semiconductor layer 222 is a semiconductor material having a composition formula of Al _x In _y Ga _(1-xy) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1), AlGaN , GaN, InAlGaN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP may be formed of any one or more.

When the first conductivity-type semiconductor layer 222 is an n-type semiconductor layer, the first conductivity-type dopant may include an n-type dopant such as Si, Ge, Sn, Se, and Te. The first conductivity type semiconductor layer 222 may be formed as a single layer or multiple layers, but is not limited thereto.

The active layer 224 is disposed between the first conductivity type semiconductor layer 222 and the second conductivity type semiconductor layer 226, and is a single well structure, a multiple well structure, a single quantum well structure, and a multiple quantum well. It may include any one of a (MQW: Multi Quantum Well) structure, a quantum dot structure, or a quantum line structure.

The active layer 224 is a well layer and a barrier layer, for example, AlGaN/AlGaN, InGaN/GaN, InGaN/InGaN, AlGaN/GaN, InAlGaN/GaN, GaAs (InGaAs) using a compound semiconductor material of group III-V element. /AlGaAs, GaP (InGaP) / AlGaP may be formed in any one or more pair structure, but is not limited thereto.

The well layer may be formed of a material having an energy band gap smaller than that of the barrier layer.

The second conductivity type semiconductor layer 226 may be formed of a semiconductor compound. The second conductivity type semiconductor layer 226 may be implemented as a compound semiconductor such as a III-V group or a II-VI group, and may be doped with a second conductivity type dopant. The second conductivity type semiconductor layer 226 is, for example, a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) , AlGaN, GaNAlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP may be formed of any one or more, for example, the second conductivity type semiconductor layer 226 may be made of Al _x Ga _(1-x) N .

When the second conductivity-type semiconductor layer 226 is a p-type semiconductor layer, the second conductivity-type dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, Ba, or the like. The second conductivity type semiconductor layer 226 may be formed as a single layer or multiple layers, but is not limited thereto.

Although not shown, an electron blocking layer may be disposed between the active layer 224 and the second conductivity type semiconductor layer 226. The electron blocking layer may have a superlattice structure, for example, AlGaN doped with a second conductivity type dopant may be disposed, and GaN having a different composition ratio of aluminum is formed as a layer. A plurality may be arranged alternately with each other.

A light-transmitting conductive layer 240 may be disposed on the second conductive type semiconductor layer 226, and the light-transmitting conductive layer 240 may be made of ITO (Indium-Tin-Oxide), or the like. Since the current spreading characteristic of the 226 is not good, the light-transmitting conductive layer 240 may receive current from the second electrode 256.

In a partial region of the light emitting structure 220, the active layer 224 and a portion of the first conductivity type semiconductor layer 222 are mesa etched from the second conductivity type semiconductor layer 226 to form the first conductivity type semiconductor layer 222. The surface is exposed.

A first electrode 252 is disposed on the exposed first conductivity-type semiconductor layer 222 and a second electrode 256 is disposed on the light-transmitting conductive layer 226, the first electrode 272 and the second electrode ( The 276 may include at least one of aluminum (Al), titanium (Ti), chromium (Cr), nickel (Ni), copper (Cu), and gold (Au), and may be formed in a single layer or multilayer structure.

Although not shown, a passivation layer made of an insulating material may be formed around the light emitting structure 220.

In FIG. 3C, the first electrode 252 and the second electrode 256 are at least partially inserted and fixed to the sheet 310 having elasticity and adhesive force, but may be easily separated from the sheet 310 in a process to be described later.

In FIG. 3D, a phosphor layer 330 including a phosphor 335 is applied on the light emitting device 200 on the sheet 310. 4A and 4B are diagrams illustrating examples of a process of applying the phosphor layer of FIG. 3C.

The phosphor layer 330 including the phosphor 335 may be formed on the sheet 310 on which the plurality of light emitting devices 200 are disposed by coating or evaporation. In FIG. 4A, a blade is used. And coating.

In FIG. 4B, the phosphor layer is fixed to the sheet 310 using a compression mold 410. That is, the phosphor layer 330 including the phosphor 335 is filled inside the compression mold 410, and the compression mold 410 is compressed on the sheet 200 on which the plurality of light emitting devices 200 are disposed to The layer 330 may be adhered to the sheet 310 to surround the light emitting device 200 and disposed thereafter, and the compression mold 410 may be removed thereafter.

The phosphor layer 330 may be formed on the sheet 310 by surrounding the circumference of the light emitting device 200 on the sheet 310 by the method of FIGS. 4A and 4B.

In addition, as shown in FIG. 3E, the phosphor layer 330 disposed on the light emitting device 200 may be removed by using the polishing device 350. At this time, since the light emitting device 200 has a substrate facing the top and two electrodes are inserted into the sheet 310 as shown in FIG. 3C, the light emitting device 200 is in contact with the polishing apparatus 350 of the light emitting device 200 The region may be a lower surface of the substrate.

In FIG. 3F, a process of removing the phosphor layer 330 is shown in detail.

The polishing device 350 rotates and removes the phosphor layer 330 disposed higher than the light emitting device 200, and the B side of the light emitting device 200 may be the bottom surface of the substrate, and at this time, the phosphor layer 300 on the B side To remove all ), the B surface and the polishing device 350 may be in direct contact. Accordingly, the surface B of the light emitting device 200 may be polished by friction with the polishing device 350, and at this time, some of the phosphors 335 in the phosphor layer 330 are formed of the polishing device 350 and the light emitting device 200. The B surface can also be polished between.

Accordingly, in FIG. 3F, some of the phosphors 335 in the phosphor layer 330 are polished to reduce their size and may exist in a broken state. Such phosphors are referred to as polished phosphors 335a. The polishing phosphor 335a may be present in a region corresponding to the upper portion of the light emitting device 200 in FIG. 3F, that is, near the B surface, which is the bottom surface of the substrate.

3G is a plan view of a'B' surface and a peripheral area of the light emitting device 200 of FIG. 3F.

In (a), when the above-described polishing device polishes the substrate of the light-emitting device in a linear motion, scratches (s) are generated on the substrate in a linear manner, and in (b), the polishing device rotates the substrate of the light-emitting device. And when polished, there is a circular scratch (s) on the substrate. In (a) and (b), the polishing phosphor 335a may be mainly distributed in the phosphor layer 330 near the bottom surface of the substrate.

In FIG. 3G, scratches generated on the substrate may remain as grooves on the bottom surface of the substrate after the manufacturing process of the light emitting device.

After completion of the polishing process described above in FIG. 3H, the phosphor layer 220 is disposed at the same height between the light emitting devices 200 of the sheet 310, and the phosphor layer 330 is disposed surrounding the side of the light emitting device. In detail, it is disposed surrounding the side surface of the substrate 210 and the side surface and the upper surface of the light emitting structure 120, and the two electrodes protrude from the phosphor layer 330 and may be inserted into the sheet 310 as described above. .

In addition, after dicing the phosphor layer 330 between each light emitting device 200, the light emitting device 200 and the phosphor layer 300 around the light emitting device 200 are separated from the sheet 310.

In FIG. 3I, one light emitting device and a phosphor layer 330 separated from each other are shown, and the top/bottom is shown interchangeably with FIG. 3C so that the substrate 210 is positioned at the bottom after being separated from the sheet 310.

The first electrode 252 and the second electrode 256 inserted in the sheet 301 are exposed to the upper portion of the phosphor layer 330, so that wire bonding may be facilitated. If the bottom surface of the substrate 210 is referred to as the first surface and the surface in the direction of the light emitting structure 220 is referred to as the second surface, a scratch (S) is formed on the first surface to form a groove, and light is extracted on the second surface. Patterns for improvement are being formed.

The depth (d) of the scratch (S) may be 1 micrometer to 3 micrometers, and the size (R) of the phosphor 335 may be about 10 micrometers, where the size (R) of the phosphor 335 is It may be the diameter of the phosphor 335 or the length of one side. Since the scratch S is formed by friction between the phosphor 335 and the substrate 210, the depth d of the scratch S may be smaller than the size R of the phosphor 335.

In FIG. 3I, the above-described polishing phosphor 335a may be disposed in a region adjacent to the first surface of the substrate 210, wherein the size (r) of the polishing phosphor 335a is the size (R) of the above-described phosphor 335 Can be smaller than The shape of the phosphor 335 may be close to a sphere, but may not form a geometrically complete sphere, and the shape of the polishing phosphor 335a may be a shape in which the phosphor 335 is broken.

In the light emitting device manufactured by the above-described process, the side and the top surface are surrounded by a phosphor layer, so that light in the first wavelength region emitted from the horizontal light emitting device in the upper direction and the side direction excites the phosphor in the phosphor layer, Since light in the wavelength region is emitted, the color temperature deviation of the light in the entire region may decrease. In addition, scratches due to friction with the polishing apparatus form grooves on the bottom surface of the substrate, and the first electrode and the second electrode may be disposed on the phosphor layer.

5 is a view showing an embodiment of a light emitting device package in which a light emitting device manufactured by the above-described process is disposed.

The light emitting device package 500 according to the embodiment includes a body 510 including a cavity, a first lead frame 521 and a second lead frame 522 installed on the body 510, and the body The light emitting device 500 according to the above-described embodiment installed at 510 and electrically connected to the first lead frame 521 and the second lead frame 522, and the molding part 550 formed in the cavity. Include.

The body 510 may be formed of a silicon material, a synthetic resin material, or a metal material. When the body 510 is made of a conductive material such as a metal material, although not shown, an insulating layer is coated on the surface of the body 510 to prevent an electrical short between the first and second lead frames 521 and 522. I can. A cavity is formed in the package body 510, and the light emitting device 200 may be disposed on a bottom surface of the cavity.

The first lead frame 521 and the second lead frame 522 are electrically separated from each other, and supply current to the light emitting device 500. In addition, the first lead frame 521 and the second lead frame 522 may reflect light generated from the light emitting device 200 to increase light efficiency, and heat generated from the light emitting device 200 to the outside. It can also be discharged.

As described above, in the light emitting device 200, the phosphor layer surrounds the side surface and the upper surface, the electrode protrudes to the outside of the phosphor layer, and the wire 250 is connected to the first lead frame 321 and the second lead frame 322. Can be electrically connected through.

The light emitting device 200 may be fixed to the bottom surface of the package body 510 with a conductive paste (not shown) or the like, and the molding part 550 may surround and protect the light emitting device 200.

The light emitting device package 500 may be mounted as one or a plurality of light emitting devices according to the above-described embodiments, but the embodiment is not limited thereto.

The above-described light emitting device or light emitting device package may be used as a light source of a lighting system, and for example, may be used in a backlight unit and a lighting device of an image display device.

When used as a backlight unit of an image display device, it may be used as an edge-type backlight unit or a direct-type backlight unit, and when used in a lighting device, it may be used for a luminaire or a bulb type light source.

The embodiments have been described above, but these are only examples and do not limit the present invention, and those of ordinary skill in the field to which the present invention belongs are not illustrated above within the scope not departing from the essential characteristics of the present embodiment It will be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

110, 500: package body 121, 521: first lead frame
122, 522: second lead frame 140, 540: wire
150, 550: molding unit 160, 335: phosphor
200: light emitting device 210: substrate
215: buffer layer 220: light emitting structure
222: first conductivity type semiconductor layer 224: active layer
226: second conductivity type semiconductor layer 240: light-transmitting conductive layer
252: first electrode 256: second electrode
310: sheet 310a: base film
310b: adhesive 310c: protective film
330: phosphor layer 335a: polished phosphor
350: polishing device 410: compression mold

Claims (8)

(A) arranging a plurality of light-emitting elements on a sheet;
(B) applying a phosphor layer including a phosphor on the light emitting device on the sheet; And
Using a polishing device, comprising the step of (c) removing the phosphor layer disposed on the light emitting device,
The light emitting device includes a substrate, a light emitting structure disposed on the substrate, a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer, and the first conductivity type semiconductor layer and the second conductivity type Including a first electrode and a second electrode respectively disposed on the semiconductor layer,
In the step (a), the substrate faces upward, and a portion of the first electrode and the second electrode are inserted into the sheet,
In the step (c), a scratch is generated on the bottom surface of the substrate by the polishing apparatus, and a plurality of grooves are formed on the bottom surface of the substrate. The method of claim 1,
In the step (c), some of the phosphors in the phosphor layer are polished to reduce the size,
A method of manufacturing a light emitting device in which the size of the phosphor adjacent to the bottom surface of the substrate in the phosphor layer is smaller than the size of the phosphor layer spaced apart from the bottom surface of the substrate. The method of claim 1,
The plurality of grooves have a depth of 1/10 to 3/10 of the size of the phosphor in the phosphor layer. The method of claim 1,
The plurality of grooves is a method of manufacturing a light emitting device having a depth of 1 micrometer to 3 micrometers. delete The method of claim 1,
A method of manufacturing a light emitting device in which the plurality of grooves are arranged in a stripe shape or concentric circle shape. delete delete

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