KR100613273B1 - Light emitting diode with vertical electrode structure and manufacturing method of the same - Google Patents

Abstract

Sequentially laminating a buffer layer, an n-type contact layer, an n-type cladding layer, a light emitting layer, a p-type cladding layer, a p-type contact layer, a conductive transparent electrode, and a light reflecting layer on the sapphire substrate, the first and second surfaces on both surfaces of the receptor substrate. Forming a receptor contact layer, forming a bonding layer over the light reflecting layer and at least one surface of the second receptor contact layer, and facing the light reflecting layer of the sapphire substrate and the second receptor contact layer of the receptor substrate And thermocompressing, removing the sapphire substrate, forming a second electrode and a first electrode on the n-type contact layer and the first receptor contact layer, respectively, the n-type contact layer and the second electrode. A color conversion light emitting diode is manufactured by a method including spin coating a phosphor layer thereon.

Vertical electrode structure, light emitting diode, sapphire substrate, etching, phosphor, spin coating

Description

Light emitting diode with vertical electrode structure and manufacturing method of the same

1 is a cross-sectional view of a light emitting diode according to the prior art.

2 is a cross-sectional view of a light emitting diode according to a first embodiment of the present invention.

3 to 8 are cross-sectional views illustrating an intermediate process of manufacturing a light emitting diode according to a first embodiment of the present invention.

9 is a graph showing etching rates of sapphire and GaN by ICP / RIE dry etching.

10 is a graph showing the etching rate when wet etching sapphire and GaN with a mixture solution of sulfuric acid (H 2 SO 4) and phosphoric acid (H 3 PO 4).

11 is a surface photograph of a nitride-based semiconductor buffer layer after removing the sapphire substrate by a wet etching method.

12 is a voltage-current characteristic curve of a nitride based semiconductor layer after the sapphire substrate is removed by a wet etching method.

13 is a cross-sectional view of a light emitting diode according to a second embodiment of the present invention.

14 to 17 are cross-sectional views illustrating an intermediate process of manufacturing a light emitting diode according to a second embodiment of the present invention.

18 is a spectrum of a white light emitting diode manufactured according to an embodiment of the present invention.

1 sapphire substrate

2 semiconductor buffer layer

3 n-type contact layer

4 n-type cladding layer

5 emitting layer

6 p-type cladding layer

7 p-type contact layer

8 conductive transparent electrode

9 light reflecting layer

10 epi side junction metal layer

11 Receptor Side Junction Metal Layer

12 second receptor contact layer

13 receptor board

14 first receptor contact layer

15 second electrode

16 first electrode

17, 400 phosphor layer

21 bonding wire

24, 25, 500 conductive paste

30 lead frames

101 first electrode leadframe

102 Second electrode leadframe

100, 200 chips

The present invention relates to a light emitting diode and a method of manufacturing the same.

The color conversion light emitting diode is mainly converted to white using a blue light emitting diode and a yellow YAG phosphor, and converted to white using an ultraviolet light emitting diode and red, green, and blue phosphors, and red, green. There are three ways to convert to white using a blue light emitting diode. In this case, the light emitting diode is used as a light source for exciting the phosphor, and the phosphor serves as a medium for wavelength conversion to absorb the excitation light source and emit light in a third color.

The method of mixing blue light emitting diodes and yellow yag phosphors is easy to manufacture, but there is a limitation in color rendering. On the other hand, when using ultraviolet excitation light sources and red, green, and blue phosphors, the color rendering is excellent, but the manufacturing cost increases. There is. In particular, these methods have a limitation in manufacturing high-brightness color conversion light emitting diodes, and red, green, and blue color conversion light emitting diodes have been proposed.

Next, a structure of a light emitting diode according to the related art will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a light emitting diode according to the prior art.

The light emitting diode is die bonded to the LED chip 200 through the conductive paste 500 on the lead frame 101, and the two electrodes of the chip 200 are connected to the lead frame through the wires 301 and 302. It is connected to the (101, 102), the phosphor mixture 400 covers the chip 200 and has a form of wrapping the entire lead frame with a resin (500).

In the conventional phosphor lamp manufacturing method, the phosphor mixture is dispensed on a die bonded chip in a lead frame by dispensing, so that the phosphor mixture covers the chip, thereby molding with epoxy. Or, the lamp has been manufactured by molding the entire lead frame with a resin containing phosphor, but when the phosphor mixture is discharged, the distribution of the phosphor is uneven, causing a change in the color coordinate (CRI: Color Rendering Index). Even if the product is manufactured in, the discharge amount, thickness, phosphor mixing ratio is different, it is difficult to produce a homogeneous color conversion light emitting diode.

In the case of using a nitride-based light emitting material in a light emitting diode, sapphire having a similar crystal structure is used as a base substrate in order to reduce the occurrence of crystal defects during epitaxial growth. However, since sapphire is an insulator, both n-type electrode and p-type electrode are formed on the growth surface side of the epi layer. As such, when both electrodes are formed on the same surface, the area of the electrode required for wire bonding must be secured, and thus the chip area of the light emitting diode must also be larger than a predetermined size. This impedes the improvement of chip yield per wafer. In addition, since the insulator is used as a substrate, it is difficult to discharge static electricity flowing from the outside, which causes a high possibility of causing a defect due to static electricity. This reduces the reliability of the device and introduces several limitations in the packaging process. In addition, sapphire has a low thermal conductivity, it is difficult to release the heat generated during the driving of the light emitting diode to the outside. Therefore, there is a restriction on the application of a large current for high output, and thus a restriction on the high luminance of the color conversion light emitting diode.

The present invention has been made to solve the above problems, and an object thereof is to provide a light emitting diode having a vertical electrode structure and a method of manufacturing the same.

Another object of the present invention is to provide a light emitting diode having a uniform distribution of phosphors and a method of manufacturing the same.

In order to achieve the above object, the present invention proposes the following light emitting diode.

An electrically conductive receptor substrate having upper and lower sides, a first electrode formed on the lower surface of the receptor substrate, a bonding layer formed on the upper surface of the receptor substrate, and having a conductive layer, a light reflection layer formed on the bonding layer, and the light A first conductive cladding layer formed on the reflective layer, a light emitting layer formed on the first conductive cladding layer, a second conductive cladding layer formed on the light emitting layer, and a second conductive cladding layer formed on the second conductive cladding layer A light emitting diode is provided that includes a second electrode, the second conductive cladding layer, and a phosphor layer coated on the second electrode and having a contact hole exposing the second electrode.

At this time, the buffer layer, the first conductivity type contact layer, the first cladding layer, the light emitting layer, the second cladding layer, the second conductivity type contact layer is In _x (Ga _y Al _1-y ) N (composition ratio x, y is 0 <x <1, 0 <y <1). Further, a first receptor contact layer formed between the first electrode and the receptor substrate, a second receptor contact layer formed between the receptor substrate and the bonding layer, the light reflection layer, and the first conductive clad layer. Preferably, the first conductive contact layer and the conductive transparent electrode formed therebetween, and the second conductive contact layer formed between the second conductive cladding layer and the second electrode, are preferred. The conductivity type may be p-type, the second conductivity type may be n-type, and the phosphor layer may include red, green, and blue phosphors and a resin. Alternatively, the phosphor layer may include a yag phosphor and a resin.

Or an insulating substrate having a first surface and a second surface, a buffer layer formed on the first surface, a first conductive contact layer formed on the buffer layer, and a first formed on the first conductive contact layer A conductive clad layer, a light emitting layer formed on the first conductive clad layer, a second conductive clad layer formed on the light emitting layer, a second conductive contact layer formed on the second conductive clad layer, and A light reflection layer formed on the second conductive contact layer, a first electrode formed on the light reflection layer, a second electrode formed on the first conductive contact layer, and a second surface of the insulating substrate A light emitting diode comprising a phosphor layer is prepared.

At this time, the buffer layer, the first conductivity type contact layer, the first cladding layer, the light emitting layer, the second cladding layer, the second conductivity type contact layer is In _x (Ga _y Al _1-y ) N (composition ratio x, y is 0 <x <1, 0 <y <1). The method may further include a conductive transparent electrode layer formed between the light reflection layer and the second conductive type contact layer, wherein the first conductive type may be n type, the second conductive type may be p type, and the phosphor The layer preferably comprises red, green and blue phosphors and resins. Alternatively, the phosphor layer may include a yag phosphor and a resin.

Such a light emitting diode is formed by sequentially laminating a buffer layer, an n-type contact layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, a p-type contact layer, a conductive transparent electrode, and a light reflection layer on a sapphire substrate. Forming a first and a second receptor contact layer, forming a bonding layer over the light reflection layer and at least one surface of the second receptor contact layer, the light reflection layer of the sapphire substrate and the second receptor contact layer of the receptor substrate Placing and facing each other, thermocompressing, removing the sapphire substrate, forming a second electrode and a first electrode on the n-type contact layer and the first receptor contact layer, respectively, It is manufactured by a method comprising the step of spin-coating a phosphor layer on the second electrode.

In this case, the method may further include removing the buffer layer after removing the sapphire substrate, and in the step of removing the sapphire substrate and the buffer layer by removing the sapphire substrate, hydrochloric acid (HCl), nitric acid (HNO ₃ ), and hydroxide hydroxide. Any one of potassium (KOH), sodium hydroxide (NaOH), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ) and alluech (4H ₃ PO ₄ + 4CH ₃ COOH + HNO ₃ + H ₂ O) Or using at least one of a wet etching method, a chemical mechanical polishing (CMP), and an ICP / RIE dry etching method using a mixed solution of one or more combinations thereof as an etchant, and lapping the sapphire substrate and the buffer layer. In the removing step, the wet etching method and the dry etching method are used together, and the wet etching method is used to etch the base substrate, and the dry etching method is used to etch the buffer layer. Available. The removing of the sapphire substrate may include back polishing the sapphire substrate and etching the back polished sapphire substrate, followed by spin coating the phosphor layer to selectively select the phosphor layer. The method may further include forming a contact hole through which the second electrode is exposed by etching. The receptor substrate is composed of any one of semiconductor substrates such as Si, GaAs, InP, InAs, conductive oxide films such as Indium Tin Oxide (ITO), ZrB, ZnO, and metal substrates such as CuW, Mo, Au, Al, Au, Ag, etc. It may be.

The step of arranging the light reflection layer of the sapphire substrate and the second receptor contact layer of the receptor substrate so as to face each other and thermocompressing may be any one or two or more of Au, Sn, In, Pd, Ag, Au, Sn, and Ag groups. Deposition and thermocompression may be performed, and the step of removing the sapphire substrate may be a step of using any one or more of mechanical polishing, wet etching, dry etching, the first electrode is ITO, InSnO, It is preferable to include any one or more of Ti / Ni / Au, Ti, Al, Rd, Pt, Ta, Ni, Cr, Au, Pd.

Alternatively, laminating a buffer layer, an n-type contact layer, an n-type cladding layer, a light emitting layer, a p-type cladding layer, a p-type contact layer, a conductive transparent electrode layer, a light reflection layer, and a first electrode layer on one surface of the sapphire substrate, the first electrode layer. Selectively etching portions of an electrode layer, a light reflection layer, a conductive transparent electrode layer, a p-type contact layer, a p-type cladding layer, a light emitting layer, an n-type cladding layer and an n-type contact layer to partially expose the n-type contact layer, and expose Forming a second electrode on the n-type contact layer, spin coating a phosphor layer on the other surface of the sapphire substrate, separating the sapphire substrate into individual chips, and flipping the individual chips into a lead frame It is prepared through a method comprising the step of bonding.

In this case, the method may further include cutting a part of the thickness of the sapphire substrate before the spin coating of the phosphor layer, and selectively etching the phosphor layer before separating the sapphire substrate into individual chips. The method may further include dividing into individual chip units.

After forming the first electrode or the second electrode may further comprise the step of heat treatment at a temperature between 300 ℃ to 700 ℃ in a furnace containing nitrogen or oxygen.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

Hereinafter, a preferred embodiment of a light emitting diode having a vertical electrode structure according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a light emitting diode according to a first embodiment of the present invention.

The light emitting diode according to the first embodiment of the present invention connects the lead frames 101 and 102, the chip 100 adhered to the lead frame 101, and one electrode of the chip 100 to the lead frame 102. Wire 21 or the like.

The chip 100 includes a first electrode 16, a first receptor contact layer 14, a receptor substrate 13, a second receptor contact layer 12, a receptor side junction metal layer 11, and an epi side junction metal layer 10. ), Light reflection layer 9, conductive transparent electrode 8, p-type contact layer 7, p-type cladding layer 6, light emitting layer 5, n-type cladding layer 4 and n-type contacting layer 3 ) Are stacked in order from the bottom up, and the second electrode 15 is formed on the n-type contact layer 3. In addition, a phosphor layer 17 for converting the wavelength of light is formed on the n-type contact layer 3. In the phosphor layer 17, a contact hole exposing the second electrode 15 is formed to bond the wire 21 to the second electrode 15 through the contact hole.

The phosphor layer 17 is a mixture of red, green, and blue phosphors with resins such as PE (polyethylene), PP (polypropylene), and acryl (Acryl) together with a precipitation prevention solution to make a liquid by stirring and melting at a temperature above room temperature. It is formed by spin coating a phosphor mixture.

Here, as the receptor substrate 13, semiconductor substrates such as Si, GaAs, SiC, and metal substrates such as Au, Al, CuW, Mo, and W are used.

The receptor side junction metal layer 11 and the epi side junction metal layer 10 are formed of AuSn, In, Pd, Ag, Au, Sn, InPd, AgIn, or the like, which are low melting point metals. The two bonded metal layers 11 and 10 are bonded by thermocompression bonding so that the receptor substrate 13 and the epi layer are attached to each other. Here, the bonding metal layers 11 and 10 may be replaced with an epoxy film having conductivity.

In addition, the buffer layer 2, the n-type contact layer 3, the n-type cladding layer 4, the light emitting layer 5, the p-type cladding layer 6 and the p-type contact layer 7 are In _x (GayAl _{1- y} ) N (x> 0, y> 0), etc., and the light reflection layer 9 is formed of a single layer or a plurality of layers including at least one of Ti, Ni, Al, Ag, Au, Rh, Pd crowds. In this case, the light reflection characteristics are excellent.

In the chip 100, the first electrode 16 surface is adhered to the lead frame 101 by the conductive paste 500, and the second electrode 15 is connected to the other electrode of the lead frame 102 through a wire. Become

In the light emitting diode having such a structure, since the second electrode 15 and the first electrode 16 are formed on both upper and lower sides of the chip, the area of the chip can be reduced. Thus, the chip yield per wafer can be improved. In addition, by using the receptor substrate 13 having excellent thermal conductivity and electrical conductivity as a chip structure, heat dissipation and electrostatic discharge are efficiently performed. In addition, since the current flows uniformly through the entire area of the chip, driving is possible even at a large current. Therefore, high light output can be obtained in the unit device. In addition, since the phosphor layer 17 can be formed uniformly, a homogeneous light emitting diode with less change in color rendering can be produced.

Next, a method of manufacturing a light emitting diode having such a structure will be described.

3 to 8 are cross-sectional views illustrating an intermediate process of manufacturing a light emitting diode according to a first embodiment of the present invention.

First, as shown in FIG. 3, a metal organic chemical vapor deposition method (MOCVD), a liquid epitaxial method (LPE), a molecular beam epitaxial method (MBE), and the like are used on a sapphire (Al ₂ O ₃ ) substrate 1. The buffer layer 2, the n-type contact layer 3, the n-type cladding layer 4, the light emitting layer 5, the p-type cladding layer 6 and the p-type contacting layer 7 are sequentially stacked.

Next, as shown in FIG. 4, the conductive transparent electrode 8 and the light reflection layer 9 are formed on the p-type contact layer 7, and the epi side bonding metal layer 10 for bonding is formed on the light reflection layer 9. Form. Here, the deposition of the light reflection layer 9 and the conductive transparent electrode 8 proceeds using an electron beam (E-Beam), thermal evaporation (Thermal Evaporation), sputtering and the like.

In addition, the first receptor contact layer 14 is formed on the upper surface of the receptor substrate 13 made of a semiconductor or metal, and the second receptor contact layer 12 and the receptor side junction metal layer 11 are formed on the lower surface.

Subsequently, in a state where the epi-side junction metal layer 10 and the receptor-side junction metal layer 11 are in contact with each other, a temperature of 200 to 500 ° C. and a pressure of 1 to 6 MPa are applied for 3 minutes to 1 hour, thereby forming the two junction metal layers 10 and 11. Fusion. When Au is used as the eutectic metal, the pressure is preferably 2.5 MP, the temperature is 300 ° C., and the welding time is about 10 minutes. In addition, such a thermocompression process is performed in a gas atmosphere such as Ar, He, Kr, Xe, Rn, or N ₂ , halogen, air (including O ₂ ) to prevent oxidation of each layer due to high temperature. Proceeding in the atmosphere, the contact layer can overcome the energy gap between the metal and the semiconductor and lower the contact resistance.

Meanwhile, the receptor substrate may be attached onto the epitaxial layer using an epoxy film having conductivity instead of the bonding metal layers 10 and 11.

Next, as shown in FIG. 5, the sapphire substrate 1 is removed by using at least one combination of mechanical polishing, wet etching, and dry etching. At this time, a part of the buffer layer 2 and the n-type contact layer 3 are also removed. The buffer layer 2 is grown at a lower temperature than other layers to have an amorphous structure. The amorphous structure is removed to increase light efficiency because the crystal structure is bad and absorbs short wavelengths around 365 nm. However, when manufacturing a light emitting diode emitting light having a long wavelength of 400 nm or more, the buffer layer 2 may not be removed. The n-type contact layer 3 is more excellent in film quality as formed later. Therefore, since the film quality is improved from the bottom to the top, it is preferable to remove the lower part of the film quality.

Next, a method of removing part of the sapphire substrate 1, the buffer layer 2 and the n-type contact layer 3 will be described in detail.

First, in order to prevent the semiconductor surface and the receptor substrate from being etched or damaged during wet etching, a protective film such as spin on glass (SOG), SiNx, and SiO ₂ is deposited about 1 μm, and then the sapphire substrate 1 is wrapped by lapping. The shaved side is mirror polished to smooth the wrapped surface. The sapphire substrate (1) lapping here is CMP (chemical mechanical polishing), ICP / RIE dry etching, mechanical polishing using alumina (Al ₂ O ₃ ) powder or hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ), phosphoric acid ( Any one of H ₃ PO ₄ ), nitric acid (HNO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH) and aluetch (Aluetch: 4H ₃ PO ₄ + 4CH ₃ COOH + HNO ₃ + H ₂ O) or It proceeds by the wet etching which uses the mixed solution by these combination as an etching solution.

At this time, the thickness of the sapphire base substrate 1 is preferably as thin as possible, but if too thin, the nitride semiconductor thin film may be damaged, so it is preferable that the thickness of the sapphire base substrate 1 be about 5um to 300um (preferably 20um to 150um). In addition, the roughness of the surface of the mirror-polished sapphire substrate 1 should be 1 um or less. This is because the roughness of the surface of the sapphire base substrate 1 may be transferred as it is to the n-type contact layer 2 when the sapphire base substrate 1 and the buffer layer 2 are etched to damage the layer structure of the light emitting diode.

After the lapping and polishing, the sample is etched by combining one or more of a wet and dry etching method to etch the sapphire base substrate 1. Sapphire etching may be preceded by dry or wet etching. For dry etching, ICP / RIE or RIE etching method is preferred. For wet etching, hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), nitric acid (HNO ₃ ), potassium hydroxide (KOH), It is preferable to etch the mixed solution by any one or a combination of sodium hydroxide (NaOH) and Aluetch (Aluetch: 4H ₃ PO ₄ + 4CH ₃ COOH + HNO ₃ + H ₂ O) with an etching solution. In order to quickly etch the sapphire base substrate 1 by the dry etching method, it is recommended to increase the ICP and RIE power as much as possible, but care should be taken because the nitride semiconductor epitaxial layer may be damaged.

At this time, the wet etching of the sapphire base substrate 1 proceeds in the following manner.

Combining any one or more of sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ) and aluene (Aluetch: 4H ₃ PO ₄ + 4CH ₃ COOH + HNO ₃ + H ₂ O) using a test sapphire substrate The etching rate of the sapphire base substrate 1 by one mixed solution is measured, and the sapphire having a thickness corresponding to 110% to 120% of the sapphire base substrate 1 is immersed in the etching solution for a time that can be etched. The reason for etching 110% to 120% is to minimize the problem that may cause non-uniformity of the sapphire substrate 1 thickness after lapping. Here, the etching rate of the buffer layer 2 represents an etching rate of 1/50 or less compared to the sapphire base substrate 1. That is, the etching selectivity of the buffer layer 2 with respect to the sapphire base substrate 1 is 50 or more. Therefore, even if the etching process is performed for a time remaining even after the sapphire base substrate 1 is completely etched, since the etching speed of the buffer layer 2 is slow, there is little fear of damaging the underlying layer. On the other hand, it is preferable to maintain the temperature of the etching solution at 100 ℃ or more in order to shorten the etching time. The heating method for maintaining the temperature of the etching solution above 100 ℃ may be a direct heating method to put the solution on the heater, or to directly contact the heater with the solution and indirect heating method using light absorption. In addition, the pressure may be increased to raise the temperature of the etching solution to a temperature higher than the boiling point of the solution.

When the sapphire base substrate 1 was wet etched, the sapphire base substrate 1 was etched 22.16 um for 20 minutes, resulting in an etching rate of 1.1 um / min. This etching rate is comparable to the dry etching rate, and considering the chip mass production, there is no problem. Wet etching is not limited by the productivity of the equipment. There is an advantage.

When the present invention is applied to mass production, an important factor is to secure process conditions for increasing the etching selectivity between the sapphire base substrate 1 and the nitride semiconductor buffer layer 2, and in particular, the buffer layer 2 is sapphire. It is effective to use as an etch stop layer. Although not illustrated in the figure, a protective film such as SiN or SiO or In _x (Ga _y Al _1-y ) N (0 <x <1, 0 <y <1) may be used as the sapphire etch stop layer. Preferably, it is effective to increase the composition ratio of Al. In addition, a protective film such as SOG, SiN, SiO, etc. is deposited on the receptor layer 12 during wet etching so that the receptor substrate 13 is not damaged or the receptor substrate 13 is not damaged by the etching solution. , Pd is preferably formed by containing at least one.

Experimental results show that metals such as Pt and Au, and thin films such as SiN and SiO, have hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), nitric acid (HNO ₃ ), potassium hydroxide (KOH), It is hardly etched into a mixed solution containing at least one of sodium hydroxide (NaOH) and aluetch (Aluetch: 4H ₃ PO ₄ + 4CH ₃ COOH + HNO ₃ + H ₂ O), but also dry such as ICP / RIE. It shows high etching resistance even in etching, and its range of application is large.

9 is a graph showing etching rates of sapphire and GaN by ICP / RIE dry etching.

As can be seen in FIG. 9, the sapphire and nitride semiconductors have increased etching speeds as the ICP and RIE powers are increased, but the etching ratio between the sapphire and nitride semiconductors decreases. These results indicate that when etching the sapphire base substrate 1 by the ICP / RIE etching method, it is difficult to stop the etching in the buffer layer (2) made of nitride-based semiconductor, and optical analysis to stop the etching in the buffer layer (2) Etch stop detector (ESD) techniques such as methods or residual gas analysis methods must be used. Even with these analytical techniques, the probability of success is low. However, in the wet etching method, by using the nitride semiconductor buffer layer 2 as an etch stop layer, a process margin, which is an essential requirement in mass production, can be secured.

10 is a graph showing the etching rate when wet etching sapphire and GaN with a mixture solution of sulfuric acid (H 2 SO 4) and phosphoric acid (H 3 PO 4).

As can be seen in Figure 10, the etching selectivity of the sapphire to the nitride-based semiconductor of the solution of sulfuric acid and phosphoric acid may be 100 or more. These results indicate that the buffer layer 2 can be effectively used as an etch stop layer of the sapphire base substrate 1, and an etching selectivity of 100 or more can be obtained even at a high temperature of 100 ° C. In particular, since the etching rate of sapphire is 1um / min or more at a specific temperature, considering the production cost, productivity, process stabilization it can be seen that the method presented in the present invention is more advantageous than any conventional method.

11 is a surface photograph of a nitride-based semiconductor buffer layer after removing a sapphire substrate by a wet etching method.

As can be seen from FIG. 11, even after the sapphire base substrate 1 is removed, it is hard to find cracks or damages of the thin film due to stress and the surface is also very clean.

12 is a voltage-current characteristic curve of a nitride based semiconductor layer after the sapphire substrate is removed by a wet etching method.

As can be seen in FIG. 12, it can be seen that no current flows until the sapphire base substrate 1 is removed, and 1 pA flows at 1 V after the sapphire base substrate 1 is removed, but ICP / RIE or After removing the nitride semiconductor buffer layer 2 by the RIE technique, it can be seen that the current rapidly increased to 40 pA. At this time, a mixed gas containing any one or more of BCL 3, Cl ₂ , HBr, and Ar is used as an etching gas of ICP / RIE or RIE.

As a result, it can be seen that the wet and dry etching techniques effectively etch the sapphire base substrate 1 and the nitride semiconductor buffer layer 2 to expose the n-type nitride semiconductor contact layer 2. This characteristic is a very important result showing that the etching process can be effectively monitored by measuring the electrical characteristics of the exposed surface using a probe station at each process step.

Next, as shown in FIG. 6, Ti, Al, Rd, Pt, Ta, which can form a transparent electrode such as ITO, InSnO, Ti / Ni / Au, a transparent electrode, or an ohmic contact on the n-type contact layer 3. , Any one of Ni, Cr, Au, or an alloy of these metals is deposited and lifted off, and heat treated at a temperature of 300 to 700 degrees in an atmosphere containing nitrogen or oxygen to make ohmic contact with the n-type contact layer 3. Forming a second electrode 15, and forming a first electrode 16 on the first receptor contact layer 14.

Subsequently, as shown in FIG. 7, the phosphor mixture 17 is spin-coated on the n-type contact layer 3 and the second electrode 15 to apply the phosphor layer 17.

Here, the phosphor mixture is a mixture of red, green and blue phosphors with resin such as PE (polyethylene), PP (polypropylene), acryl (Acryl) together with the precipitation prevention solution to make a liquid by stirring and melting at a temperature above room temperature, centrifugal force Coating using a rotary coating machine using.

Next, as shown in FIG. 8, the phosphor layer 17 is photo-etched to form contact holes exposing the second electrode 15, and dicing (sawing) the light emitting diode substrate on which each layer is formed. Separate into individual chips.

Next, as shown in FIG. 2, the chip is mounted on the lead frame 101 using a conductive paste 500 such as silver (Ag) paste, and the wire 21 is bonded to meet the second electrode 15. One lead frame 102.

As described above, since the sapphire substrate 1 is removed by back grinding and dry or wet etching, the productivity is greatly improved, and in the case of the laser lift-off method, thermal damage that may be received by the epi layer can be prevented.

In addition, when the sapphire substrate is removed through backside polishing and etching, the surface of the n-type contact layer 3 forms fine acids and valleys, thereby concentrating light. In addition, since the phosphor layer 17 is formed by spin coating, the phosphor layer 17 is formed to have a uniform thickness. Therefore, it is possible to stably produce a color conversion light emitting diode with little change in color coordinates.

In the first embodiment of the present invention, the back surface grinding and etching are used as a method of removing the sapphire substrate 1, but a laser lift-off (LLO) method may be used.

In addition, the first electrode 16 and the second electrode 15 can be formed in a single layer or multiple layers. For example, the second electrode 15 may be formed as a single layer or a plurality of layers including at least one of Ti, Al, Ni, Au, Rh, Pd, Pt, and the like, and the first electrode 16 Silver, Ni, Au, Ti, Rh, Pd, Al, Cr, Pt, can be formed of a single metal or alloy containing any one or more, these metal layers can be converted into an alloy through heat treatment or the like.

The present invention will be described with respect to the second embodiment.

13 is a cross-sectional view of a light emitting diode according to a second embodiment of the present invention.

The light emitting diode according to the embodiment of the present invention includes a lead frame 30, a chip that is flip-chip bonded to the lead frame 30, and the like.

The chip has the following structure.

On the sapphire substrate 1, the buffer layer 2, the n-type contact layer 3, the n-type cladding layer 4, the light emitting layer 5, the p-type cladding layer 6, the p-type contact layer 7, the conductive transparent electrode (8), the light reflection layer 9 and the first electrode 16 are sequentially stacked, and the first electrode 16, the light reflection layer 9, the conductive transparent electrode 8, the p-type contact layer 7, The second electrode 15 is disposed on the surface of the n-type contact layer 3 in which a portion of the p-type cladding layer 6, the light emitting layer 5, the n-type cladding layer 4, and the n-type contact layer 3 are removed and exposed. ) Is formed. In addition, a phosphor layer 17 for converting the wavelength of light is formed on the lower surface of the sapphire substrate 1.

Here, the phosphor layer 17 is spin-coated a phosphor mixture made of a liquid by mixing the red, green and blue phosphor in a resin such as PE, PP, acrylic (Acryl) together with a precipitation prevention solution, stirring and melting at a temperature above room temperature It is formed by spin coating.

In addition, the first electrode 16 and the second electrode 15 can be formed in a single layer or multiple layers. For example, the second electrode 15 may be formed of a single layer or a plurality of layers including any one or more of Ti, Al, Ni, Au, Rh, Pd, Pt, and the like, and the first electrode 16 may be formed of Ni. It may be formed of a single metal or alloy containing at least one of Au, Ti, Rh, Pd, Al, Cr, Pt, Ta and the like.

This chip is inverted so that the phosphor layer 17 is turned up and bonded to the lead frame 30. The chip is adhered to the lead frame 30 by conductive pastes 24 and 25 such as silver (Ag) paste.

In the light emitting diode having such a structure, since the phosphor layer 17 is formed uniformly, the color rendering change of the light emitting diode is small.

A method of manufacturing a light emitting diode having such a structure will be described.

14 to 17 are cross-sectional views illustrating an intermediate process of manufacturing a light emitting diode according to a second embodiment of the present invention.

First, a metal organic chemical vapor deposition method (MOCVD), a liquid epitaxial method (LPE), a molecular beam epitaxial method (MBE), or the like is applied on a sapphire (Al ₂ O ₃ ) substrate 1, and the buffer layer 2, n The n-type cladding layer 3, the n-type cladding layer 4, the light emitting layer 5, the p-type cladding layer 6 and the p-type contacting layer 7 are sequentially stacked. Here, the buffer layer 2, the n-type and p-type cladding layers 4, 6 and the light emitting layer 5 are formed of In _x (Ga _y Al _1-y ) N or the like. Subsequently, the conductive transparent electrode 8 and the light reflection layer 9 are formed on the p-type contact layer 7, and the first electrode 16 is formed of metal such as gold (Au) on the light reflection layer 9. . Here, the deposition of the light reflection layer 9 and the conductive transparent electrode is performed by using an electron beam (E-Beam), thermal evaporation (Sputtering), sputtering and the like.

Next, as shown in FIG. 14, the first electrode 16, the light reflection layer 9, the conductive transparent electrode 8, the p-type contact layer 7, the p-type cladding layer 6, the light-emitting layer 5, A portion of the n-type cladding layer 4 and the n-type contact layer 3 is selectively etched to partially expose the n-type contact layer 3, and the second electrode 15 is placed on the n-type contact layer 3. After the formation, the sapphire substrate 1 is etched or etched after polishing to cut off part of the thickness.

Subsequently, as shown in FIG. 15, the phosphor mixture is spin coated on the sapphire substrate 1 to form the phosphor layer 17.

Here, the phosphor mixture is mixed at least one of the red, green and blue phosphor, or the yellow Yag phosphor is mixed with resin, such as PE, PP, Acryl, together with the precipitation prevention solution and stirred at a temperature above room temperature Melt into liquid phase and coated using a rotary coater using centrifugal force. In this case, the chip of the excitation light source may be an ultraviolet light source or a blue light source, respectively.

Next, as shown in FIG. 16, the phosphor layer 17 is selectively etched and divided into individual chip units.

Next, as shown in FIG. 17, the light emitting diode substrate in which each layer is formed is diced and separated into individual chips.

Next, as shown in FIG. 13, individual chips are flip-chip bonded.

18 is a spectrum of a white light emitting diode manufactured according to an embodiment of the present invention.

A white light emitting diode was manufactured by mixing red, green and blue Villag phosphors, followed by spin coating. The color coordinates were x = 0.31 and y = 0.33, and the color rendering properties were 85 or more.

As described above, in the present invention, since the phosphor layer 17 is formed by spin coating, the phosphor layer 17 is formed to have a uniform thickness, thereby not only stably producing a light emitting diode having a small change in color coordinate value, but also Since high luminance has been achieved, it is expected that high luminance color conversion light emitting diodes can be manufactured, which will serve as a driving force for future applications as lighting sources.

Although the present invention has been described with reference to the embodiments shown in the accompanying drawings, this is merely exemplary, and those skilled in the art may understand that various modifications and equivalent other embodiments are possible. There will be. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

As described above, when the color conversion LED is manufactured using the vertical electrode type LED and the phosphors of red, green, blue, and white light, the second electrode and the first electrode are formed separately on the upper and lower sides of the chip, thereby reducing the area of the chip. Can be reduced, improving chip yield per wafer. In addition, when a color conversion light emitting diode is manufactured using a vertical electrode type light emitting diode or a flip chip light emitting diode, heat emission and electrostatic emission are efficiently performed, thereby obtaining a high luminance color conversion light emitting diode.                     

In addition, in the present invention, since the sapphire substrate is removed using back grinding and dry or wet etching, productivity is greatly improved, and thermal damage that an epitaxial layer can receive in the case of a laser lift-off method can be prevented.

In addition, when the phosphor layer is spin coated, the phosphor layer can be formed to have a uniform thickness, so that a color conversion light emitting diode having a small change in color coordinate value can be stably produced.

Claims (26)

Receptacle substrate having both upper and lower sides and conductive A first electrode formed on the bottom surface of the receptor substrate, A bonding layer formed on an upper surface of the receptor substrate and having conductivity and ohmic characteristics; A light reflection layer formed on the bonding layer, A first conductivity type contact layer formed on the light reflection layer, A first conductivity type clad layer formed on the first conductivity type contact layer, A light emitting layer formed on the first conductive cladding layer, A second conductive clad layer formed on the light emitting layer, A second conductivity type contact layer formed on the second conductivity type clad layer, A second electrode formed on the second conductivity type contact layer, A phosphor layer coated on the second conductive clad layer and the second electrode and having a contact hole exposing the second electrode; Light emitting diode comprising a. In claim 1, The first conductivity type contact layer, the first conductivity type cladding layer, the light emitting layer, the second conductivity type cladding layer, and the second conductivity type contact layer are In _x (Ga _y Al _1-y ) N (composition ratio x, y is 0 < A light emitting diode consisting of x <1, 0 <y <1). In claim 1, A first receptor contact layer formed between the first electrode and the receptor substrate, A second receptor contact layer formed between the receptor substrate and the bonding layer, A first conductive contact layer and a conductive transparent electrode formed between the light reflection layer and the first conductive clad layer; A second conductive contact layer formed between the second conductive clad layer and the second electrode Light emitting diodes further comprising. In claim 2, Wherein the first conductivity type is p-type and the second conductivity type is n-type. In claim 1, The phosphor layer comprises a red, green and blue phosphor and a resin. In claim 1, The phosphor layer includes a yag phosphor and a resin. delete delete delete delete delete delete Stacking a buffer layer, an n-type contact layer, an n-type cladding layer, a light emitting layer, a p-type cladding layer, a p-type contact layer, a conductive transparent electrode, and a light reflection layer on the sapphire substrate in order; Forming first and second receptor contact layers on both surfaces of the receptor substrate, Forming a bonding layer on the light reflection layer and at least one surface of the second receptor contact layer, Arranging the light reflection layer of the sapphire substrate and the second receptor contact layer of the receptor substrate so as to face each other and thermally compressing the same; Removing the sapphire substrate, Forming a second electrode and a first electrode on the n-type contact layer and the first receptor contact layer, respectively; Spin coating a phosphor layer on the n-type contact layer and the second electrode Method of manufacturing a light emitting diode comprising a. In claim 13, And removing the buffer layer after removing the sapphire substrate. The method of claim 14, In the step of lapping the sapphire substrate and the buffer layer, hydrochloric acid (HCl), nitric acid (HNO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH), sulfuric acid (H ₂ SO ₄ ), and phosphoric acid (H ₃ PO ₄ ) And a wet etching method using a mixed solution of any one or a combination of one or more of (4H ₃ PO ₄ + 4CH ₃ COOH + HNO ₃ + H ₂ O) as an etchant, chemical mechanical polishing (CMP) and A method of manufacturing a light emitting diode using at least one of an ICP / RIE dry etching method and mechanical polishing. The method of claim 15, In the removing of the sapphire substrate and the buffer layer, the wet etching method and the dry etching method are used together, and the wet etching method is used to etch the base substrate, and the dry etching method is used to etch the buffer layer. Method for manufacturing a light emitting diode. In claim 13, The removing the sapphire substrate may include back polishing the sapphire substrate by a mechanical polishing method and etching the back polished sapphire substrate. In claim 13, And spin-coating the phosphor layer to selectively etch the phosphor layer to form contact holes exposing the second electrode. In claim 13, The receptor substrate is composed of any one of semiconductor substrates such as Si, GaAs, InP, InAs, conductive oxide films such as Indium Tin Oxide (ITO), ZrB, ZnO, and metal substrates such as CuW, Mo, Au, Al, Au, Ag, etc. Method for manufacturing a light emitting diode. In claim 13, Arranging the light reflection layer of the sapphire substrate and the second receptor contact layer of the receptor substrate so as to face each other and thermally compressing the Ti, Ni, Au, Sn, In, Pd, Ag, Sn, Ag, Rh to obtain ohmic characteristics Method of manufacturing a light emitting diode which is the step of depositing any one or two or more of the group and thermocompression bonding. In claim 13, The removing of the sapphire substrate is a method of manufacturing a light emitting diode that proceeds using any one or more of mechanical polishing, wet etching, dry etching. In claim 13, The first electrode may include at least one of ITO, InSnO, Ti / Ni / Au, Ti, Al, Rd, Pt, Ta, Ni, Cr, Au, Pd. delete delete delete delete

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