KR20070000953A - Light emitting diode device having heat dissipation rate enhancement and preparation method thereof - Google Patents

Abstract

An LED device and a method for manufacturing the same are provided to easily separate substrates by using two adhesives with different viscosity each other. A light emitting diode part grown on a sapphire substrate is bonded with a first surface of a first substrate by using a first adhesive. A second surface of the first substrate is bonded with a first surface of a second substrate by using a second adhesive having a relatively low viscosity compared to the first adhesive. The second surface of the sapphire substrate is processed, and the second substrate is discrete. The resultant structure is discrete into a unit chip. The processed second surface of the sapphire substrate is connected to a lead frame, and the first substrate is discrete.

Description

LIGHT EMITTING DIODE DEVICE HAVING HEAT DISSIPATION RATE ENHANCEMENT AND PREPARATION METHOD THEREOF}

1 is a cross-sectional structural view of a gallium nitride based light emitting diode device for low and medium output.

2 is a cross-sectional structural view of a high output gallium nitride-based flip chip light emitting diode device.

3 is a schematic diagram showing a manufacturing process of a top-emitting LED device according to the present invention.

Description of the main parts of the drawing

10: sapphire substrate 20: lead frame

30: submount 40: flip chip bonding metal

11: cathode 12: anode

13: light emitting layer

The present invention relates to a method for manufacturing a high power front light emitting diode device having a markedly improved heat dissipation efficiency. More specifically, the present invention relates to a sapphire substrate to improve the heat dissipation efficiency due to a poor sapphire substrate. The present invention relates to a method of manufacturing a top-emitting light emitting diode device that significantly reduces the thickness of the light emitting diode device, and to a light emitting diode device manufactured by the method.

Blue and green light emitting diodes made of gallium nitride compound semiconductors have been successfully commercialized in the late 1990s and now form a vast market. White light emitting diodes are also made of gallium nitride compound semiconductors, which have recently been commercialized and are growing at a rapid rate. In particular, the white light emitting diode is expected to replace the conventional incandescent and fluorescent lamps, the situation is actively studied worldwide.

A sapphire substrate having a thickness of 430 μm is mainly used for growing a gallium nitride compound semiconductor for manufacturing the light emitting diode. Since the sapphire substrate is an insulator, the anode and cathode electrodes of the light emitting diode are formed on the front surface of the wafer.

In general, a gallium nitride-based light emitting diode for low and medium outputs has a sapphire substrate 10 having a crystal structure grown on the lead frame 20 as shown in FIG. 1, and then the positive electrodes 11 and 12 are moved. Made by connecting to the top. In this case, in order to improve the heat dissipation efficiency, the sapphire substrate with an initial thickness of about 430 μm is thinned to about 80 μm and attached to the lead frame. However, since the thermal conductivity of the sapphire substrate is about 50 W / m · K, even if the thickness is about 80 μm, the thermal resistance is large. Therefore, the front light emitting structure shown in FIG. 1 is mainly used for manufacturing low and medium output light emitting diodes, and is difficult to be applied to high output.

In order to further improve the heat dissipation characteristics, a flip chip LED method was mainly studied as shown in FIG. 2 at the beginning of the development of a high output gallium nitride based LED device having a chip area of 1 × 1 mm ² or more.

In the flip chip method, a chip having a light emitting diode structure is attached to a submount 40 such as a silicon wafer (150 W / mK) or an AlN ceramic (about 180 W / mK) substrate having excellent thermal conductivity. In this case, since the heat is released through the submount substrate 30, the heat dissipation efficiency is improved, compared with the case of dissipating heat through the sapphire substrate 10, but the manufacturing process is not only more complicated than the top emission type of the general structure. Due to the low yield of the flip chip bonding process, production costs are high and mass production is inferior.

Due to the above-mentioned problems, in recent years, leading companies have tended to abandon the mass production of flip chip light emitting diodes and mass-produce existing top emitting high power light emitting diodes, but the life of the device is shortened due to the low thermal conductivity of the sapphire substrate. Are facing thermal problems. Therefore, there is an urgent need in the art for improving the heat dissipation efficiency of a top emission type high output light emitting diode having a simple manufacturing process and excellent mass productivity.

On the other hand, the sapphire substrate provided in the top light emitting diode device according to the prior art is processed by the following process. That is, the surface on which the light emitting diode portion is formed on the sapphire substrate is bonded to the ceramic block having a larger size than the sapphire substrate using wax or the like. Wax is a solid at room temperature, but the liquid changes at a temperature of about 125 ℃, using this property to melt the wax at a temperature of about 125 ℃ by bonding the sapphire substrate and the ceramic block is cooled to room temperature. The back surface of the sapphire substrate firmly fixed to the ceramic block by wax is thinned to about 80 μm by grinding, lapping and polishing, and then the ceramic block is heated to a temperature above the melting point of the wax to separate the sapphire substrate. Through such processing, the sapphire substrate, which had an initial thickness of about 430 μm, is processed to a thickness of about 80 μm. Through such processing, the sapphire substrate, which had an initial thickness of about 430 μm, is processed to a thickness of about 80 μm. However, when the thickness is thinner for improving heat dissipation, not only the warpage of the sapphire substrate becomes serious but also the sapphire substrate is broken only by separating from the ceramic block. Thus, the limit of sapphire substrate thickness that can be realized by current processing techniques is on the order of 80 μm.

In addition, the above-described method can be satisfied because the thickness variation of the sapphire substrate or metal (silicon, etc.) wafer to be polished is small, but when the wax is heated and melted to separate the sapphire substrate, the surface of the sapphire substrate or metal (silicon, etc.) wafer is A problem arises in that a large amount of toxic organic solvent must be used to completely remove the wax remaining in the phase. In addition, a compound or foreign dust or the like contained in the wax may be transferred as a dimple onto the polishing sapphire substrate or the metal (silicon, etc.) wafer surface to cause product damage such as worsening the finish state of polishing. In addition, the problem of subtly etching the surface of the sapphire substrate or metal (silicon, etc.) wafer during cleaning to remove the wax also occurs.

In order to solve such a problem, the present inventors recognize the above-mentioned problems occurring when the sapphire substrate is separated from the bonded body of the sapphire substrate and the ceramic block processed to a desired thickness range, and fix the sapphire substrate to solve the problem. In addition to the ceramic block (second substrate), which serves as a main part, another substrate (first substrate), that is, the sapphire substrate is continuously fixed even in the unit chip forming step, and then the processed sapphire substrate is bonded to the lead frame. It was only at this stage that a new manufacturing method using the first substrate, which was separated from the sapphire substrate, between the sapphire substrate and the second substrate was attempted. At the same time, by using a bonding agent having different physical properties as the bonding agent used in bonding the first substrate and the second substrate, it is possible to easily separate the first substrate and the second substrate from the bonding body in sequence, Because of this, it is intended to realize the ease of manufacturing process, process yield and quality improvement of the final product.

Accordingly, an object of the present invention is to provide a light emitting diode device assembly and a unit chip manufactured therefrom that are easy to process and fix the sapphire substrate, as well as to form a unit chip thereafter.

In addition, the present invention by performing a process that is different from the grinding (grinding) process, which simply grinds the conventional sapphire substrate, by dramatically reducing the thickness of the sapphire substrate more than 80㎛ not only significantly improve the heat dissipation efficiency, but also manufacture Another object of the present invention is to provide a method of manufacturing a light emitting diode device in which the simplicity and mass production of the process are realized.

The present invention (a) a first substrate made of a material capable of performing a braking process; And (b) a sapphire substrate having light emitting diode portions grown on the first surface, wherein the first surface of the first substrate and the light emitting diode portions of the sapphire substrate are bonded to each other by a bonding agent. After processing the thickness of the sapphire substrate in the range of 5 to 80㎛ range to provide a separate unit chip (unit chip).

In addition, the present invention provides a method of manufacturing a light emitting diode device comprising a light emitting diode portion grown on a sapphire substrate, (a) the first surface of the light emitting diode portion and the first substrate grown on the sapphire substrate Bonding using; (b) joining the second surface of the first substrate and the first surface of the second substrate in the resulting bonded body of step (a) using a second bonding agent having a different adhesive force lowering property than the first bonding agent; ; (c) after processing the second surface of the sapphire substrate in the resulting conjugate of step (b), separating the second substrate; (d) separating the bonded body from which the second substrate is separated into unit chips; And (e) bonding a second surface of the processed sapphire substrate of the unit chip to a lead frame, and then separating the first substrate.

Hereinafter, the present invention will be described in detail.

In the present invention, in the conventional sapphire substrate processing, the sapphire substrate is added to a second substrate (ceramic block) for fixing and processing the sapphire substrate, and the sapphire substrate processed to a desired thickness range is processed after the step, that is, the unit chip ( In addition to achieving structural stability by continuously fixing unit chip formation stages, a combination of a first substrate capable of forming a unit chip by easily performing a scribing and / or breaking process in a state of being bonded to a sapphire substrate is used. Characterized in that.

In particular, in order to solve the above-mentioned problems that occur when the sapphire substrate, the first substrate, and the second substrate are sequentially bonded and then separate the substrates from these bonded bodies, different adhesion strength properties such as melting point and light irradiation may be used. It is the biggest feature to use the 1st binder and the 2nd binder which have the sensitivity to water, solubility, etc.

Due to the above characteristics, the light emitting diode device of the present invention can exhibit the following effects.

1) The ceramic block (second substrate) used in the conventional sapphire substrate processing was used only for thinning the sapphire substrate, and then separated from the sapphire substrate to form the unit chip. In contrast, the first substrate of the present invention is bonded again to the ceramic block (second substrate) in a state of being bonded to the sapphire substrate to process the sapphire substrate to a desired thickness, for example, less than 80 μm, and then the sapphire substrate and the first Even if the bonded body of the 1st board | substrate is isolate | separated, the sapphire board | substrate can be prevented from bent or broken by the fixing by a 1st board | substrate.

2) In the present invention, not only the process of processing the surface of the sapphire substrate (about 70 ° C. or less, about 2 hours) can be performed as the first bonding agent and the second bonding agent, but the processed sapphire substrate, the first substrate, and the second substrate are By using materials having different adhesion lowering properties so that the substrates can be sequentially separated from the bonded state (secondary assembly), not only does not affect the finishing state of the polished sapphire substrate, but also Ease of use, process yield improvement and final product performance can be improved.

3) In addition, by using a substrate made of a material capable of performing a braking process as the first substrate, not only is it easy to form a unit chip through the braking process in a state in which the sapphire substrate is bonded, but also the production yield is improved and mass production is secured. can do.

4) Furthermore, since the first substrate is separated from the sapphire substrate when the processed sapphire substrate is structurally secured through bonding to the lead frame, it occurs when the conventional sapphire substrate is separated from the ceramic block (second substrate). Problems such as bending or cracking of the sapphire substrate do not occur. Therefore, by implementing the final thickness of the sapphire substrate to 80 μm or less, preferably 40 μm or less, which is a limitation of the conventional manufacturing process, it is possible to improve heat dissipation efficiency about 2 times or more than that of the front light emitting diode device.

The light emitting diode assembly according to the present invention includes a sapphire substrate on which a first substrate and a light emitting diode portion are grown, and they are bonded to each other. One embodiment of the present invention will be described in more detail, including: (a) a first substrate made of a material capable of performing a breaking process; And (b) a sapphire substrate on which a light emitting diode portion is grown on a first surface, wherein the first surface of the first substrate and the light emitting diode portions of the sapphire substrate are bonded to each other by a bonding agent.

The first substrate constituting the bonded body is not particularly limited in material, size, or thickness thereof, as long as the sapphire substrate is fixed to the sapphire substrate through a light emitting diode unit. Since it should be possible to perform it is preferably composed of a material having a property that is as good as possible, for example silicon or alumina. In addition, it is preferred to have the same size and shape as possible with the sapphire substrate, but is not limited thereto. Preferred sizes and thickness ranges of the first substrate are 2 inches in size and 150-300 μm thick, respectively, but are not limited thereto. Non-limiting examples of the first substrate include silicon wafers and alumina ceramic wafers.

The sapphire substrate constituting the bonded body of the present invention can be used as long as the light emitting diode portion is grown on the first surface.

The light emitting diode unit may form a p-type layer, an active layer (light emitting layer), and an n-type layer by using a conventional gallium nitride compound known in the art, and non-limiting examples thereof include GaN, GaAIN, InGaN, InAlGaN or the like. Mixtures and the like. In addition, the active layer (aka light emitting layer) may be a single quantum well structure or multiple quantum well structure (MQW). In addition to the p-type layer, the active layer, and the n-type layer described above, other buffer layers may be included. By controlling the components of the gallium nitride-based compound it is possible to freely manufacture a light emitting diode from a long wavelength to a short wavelength, through which can be applied to all light emitting diodes without being limited to the blue nitride-based light emitting diode having a 460nm. In this case, the light emitting diode portions may be continuously present on the sapphire substrate, or one or more light emitting diode portions may be present on the sapphire substrate at predetermined intervals.

The sapphire substrate may not be processed, or it may be grinding, lapping, or polishing. In the case of a processed sapphire substrate, the processed surface (second surface) is formed with a mirror surface. In addition, the thickness of the processed sapphire substrate is not particularly limited, but is preferably in the range of 5 to 80 ㎛ as possible to increase the heat dissipation efficiency.

The present invention provides a unit chip separated after processing the thickness of the sapphire substrate in the range of 5 to 80㎛ of the above-described bonded body.

At this time, the unit chip separation method may be performed according to a conventional method well known in the art, for example, scribing (breaking) and breaking (breaking) process.

The present invention provides a light emitting diode device made through the above-described assembly and unit. In this case, the light emitting diode device is not limited to a manufacturing method, an output method, and a light emitting wavelength range. Accordingly, the light emitting diode device of the present invention may be manufactured according to various methods, but in one preferred embodiment, (a) the first surface of the light emitting diode portion grown on the sapphire substrate and the first substrate is a first bonding agent. Bonding using; (b) joining the second surface of the first substrate and the first surface of the second substrate in the resulting bonded body of step (a) using a second bonding agent having a different adhesive force lowering property than the first bonding agent; ; (c) after processing the second surface of the sapphire substrate in the resulting conjugate of step (b), separating the second substrate; (d) separating the bonded body from which the second substrate is separated into unit chips; And (e) bonding the second surface of the processed sapphire substrate of the unit chip to the lead frame, and then separating the first substrate.

Hereinafter, the processing steps of the most differentiated features, such as sapphire substrate of the manufacturing method of the present invention will be described in detail. 3 illustrates the sapphire processing step.

1) bonding step of the first substrate (see FIG. 3B)

The light emitting diode portion (see FIG. 3A) grown on the sapphire substrate and the first surface of the first substrate are bonded using a first bonding agent. In this case, the first bonding agent which can be used to bond the sapphire substrate and the first substrate on which the light emitting diode portion is grown is a conventional bonding material known in the art, for example, a polymer material in a solid state at room temperature (eg, an adhesive resin, a UV curing resin). , Thermoplastic resin, etc.) may be used a material capable of performing a sapphire substrate processing step (about 2 hours at about 70 ℃) in a state of being bonded to the sapphire substrate. Thus, the bonded form of the sapphire substrate and the 1st board | substrate joined using the 1st bonding agent is as FIG. 3B.

2) bonding step of the second substrate (see Fig. 3c)

The second surface of the first substrate and the first surface of the second substrate are bonded using the second bonding agent. Thus, the cross section where the 2nd surface of the 1st board | substrate and the 1st surface of the 2nd board | substrate of the junction body of a sapphire substrate and a 1st board | substrate were joined is as FIG.

As long as the second substrate also serves to fix the sapphire substrate, the material, size or shape thereof is not particularly limited. In particular, since the second substrate is typically used in a form attached to the lapping and polishing equipment, it may be appropriately determined according to the specifications of the lapping and polishing equipment to be used as much as possible. A preferred thickness range of the second substrate is about 3 to 5 cm, and non-limiting examples thereof include ceramic blocks and the like.

As described above, the second bonding agent which can be used to bond the sapphire substrate with the first substrate and the second substrate is a polymer material in a solid state at room temperature, which is capable of performing a processing process of the sapphire substrate in a state of being bonded to the sapphire substrate as described above. For example, adhesive resin, UV hardening resin, a thermoplastic resin, etc. can be used.

At this time, in order to selectively separate the first substrate and the second substrate from the bonding body with the sapphire substrate in order, the first bonding agent and the second bonding agent, as described above, differ from each other in terms of adhesion lowering properties such as adhesion lowering temperature, It is required to have a melting point, sensitivity to light irradiation, selective solubility in a solvent and the like. In fact, it is preferable that the adhesive force is lowered under different conditions, or the adhesive force becomes first binder> second binder under the same conditions.

That is, in order to preferentially separate the second substrate from the final bonded body (secondary bonded body) composed of the sapphire substrate-first binder layer-first substrate-second binder layer-second substrate shown in FIG. By using the unique adhesive lowering properties (e.g., adhesive lowering temperature, melting point, sensitivity to light irradiation or selective solubility in a specific solvent), which are distinguished from the binder, the bonding between the sapphire substrate and the first substrate is achieved. Only the second substrate can be easily separated while being kept intact. In addition, since the sapphire substrate is fixed by the bonded first substrate even after separating the second substrate, structural stability is maintained as it is.

Therefore, it is appropriate that the first bonding agent has different adhesive force lowering properties from the second bonding agent to be used later. At this time, although the physical properties of the adhesive force is not particularly limited, it can be largely represented by the temperature of the adhesive force, melting point, sensitivity to light irradiation, selective solubility in a solvent, and the like.

One of the physical properties that distinguish the first binder and the second binder of the present invention is the adhesion lowering temperature, which means the temperature at which their lowering of adhesive properties occurs before the state transition of the material occurs. Although the adhesive force lowering temperature of each of the first adhesive agent and the second adhesive agent is not particularly limited, it is appropriate that the adhesive force lowering does not occur at room temperature so that the processing step of the sapphire substrate can be performed. T ₁ ) and the temperature difference in adhesion decrease between the second bonding agent (T ₂ ) | T ₁ -T ₂ | Material with ≧ 10 ° C. When the temperature is less than 10 ° C., since the adhesive force of the first binder may be decreased when the second binder is separated, and thus peeling of the first substrate may occur, precise temperature management is required. Moreover, since the process (polishing) process of a sapphire substrate surface, and a unit chip formation process progress at normal temperature, it is good that the said 1st bonding agent and a 2nd bonding agent make sufficient adhesion at normal temperature.

The first bonding agent and the second bonding agent may be a cooling peeling type in which the adhesive force is lowered below a specific temperature or a heating peeling type in which the adhesive force is lowered above a specific temperature. In order to sequentially separate the second bonding agent and the first bonding agent, the adhesive force lowering temperature (T ₁ ) of the heat-peelable first bonding agent is 10 ^o C than the adhesive force lowering temperature (T ₂ ) of the heat-peeling type second bonding agent. It is preferable that it is larger than (T ₁ ≥ T ₂ ), on the contrary, the adhesive force lowering temperature (T ₁ ) of the cold peeling type first bonding agent is 10 ^o C than the adhesive force lowering temperature (T ₂ ) of the cold peeling type second bonding agent. It is preferable that the abnormality is smaller than (T ₁ ≦ T ₂ ). However, when both the first binder and the second binder are cooled and peeled off, they must be lowered by 20 ^o C or more than at room temperature, so a large cooling device is required, and since there is a risk of moisture condensation due to the surface temperature drop, It is preferable that all the 2nd bonding agents are the heat peeling type.

As a concept similar to the pressure drop temperature, the first binder and the second binder of the present invention preferably have different melting points (primary transition temperature). At this time, in order to separate (desorb) the first binder and the second binder sequentially, the melting temperature of the second binder is 40 to 120 ° C, preferably 70 to 120 ° C, more preferably 80 to 100 ° C. It is a range and melting temperature of a 1st binder is 80-220 degreeC, Preferably it is 120-140 degreeC.

Non-limiting examples of the first binder and the second binder usable through the above-described physical properties include side chain crystalline polymers, pressure-sensitive adhesives, thermal blowing agents, heated foam adhesives, high boiling point plasticizers, organic crystals or mixtures thereof. . In particular, about 15 ^o C It is desirable to have a melting point (primary transition temperature) that occurs over a narrower temperature range.

Side chain crystalline polymers include side chain crystalline repeat units derived from acrylate or methacrylate esters and side chain amorphous repeat units derived from acrylate or methacrylate esters. That is, -COOR ₁ of the side chain crystalline repeat unit R ₁ is an alkyl group having 14 or more carbon atoms, and -COOR ₂ of the branched amorphous repeating unit R ₂ is a straight or branched chain alkyl group having one or more carbon atoms. Other crystallizable monomers include fluor acrylate, methacrylate and vinyl ester polymer corresponding acrylates, substituted acrylamide and maleimide polymers, polyalkyl vinyl ethers, holly alkyl ethylene oxides, polyisocyanates, amine containing monomers or alcohol containing monomers. And polyurethanes, polysiloxanes and polylans, alkyl styrene polymers reacted with alkyl isocyanates, polyesters and polyesters. It is possible to change the melting point of 20 to 100 ℃ by the type of the side chain and the number of crystalline units of the side chain crystalline polymer, wherein the melting point is narrower than 15 ℃, preferably less than 5 ℃ relatively narrow temperature Dissolution occurs remarkably over a range. Therefore, if the predetermined temperature is slightly changed from the arbitrarily set temperature, the adhesive force of the pressure-sensitive adhesive rapidly decreases between the crystals and the amorphous of the side chain crystalline polymer, so that the substrate is easily peeled from the joined body.

As the pressure-sensitive adhesive, a conventional adhesive known in the art may be used, and non-limiting examples thereof include a natural rubber adhesive, a styrene / butadiene latex base adhesive, an ABA block copolymer type thermoplastic rubber (A denotes a thermoplastic polystyrene end block). , An acrylic adhesive such as polyisoprene, polybutadiene or polyethylene / butylene), butyl rubber, polyisobutylene, polyacrylate and vinyl acetate / acrylic ester copolymer, polyvinylmethylether, polyvinyl Vinyl ether copolymers such as ethyl ether and polyvinylisobutyl ether, or mixtures thereof. The pressure-sensitive adhesive component may be a polymer or a simple mixture of polymers or a polymer composition containing a plasticizer, a tackifier, a vira, a stabilizer, a defoamer, an antistatic agent, and the like. In addition, non-limiting poly Olga a linear or three-dimensional structure consisting of a pressure-sensitive adhesive consisting of a silicone composition to the R ₂ SiO units (D unit), or R ₃ SiO _{0 .5} units (M units) and SiO ₂ (Q unit) no Siloxane (R is a C1-C10 linear or cyclic alkyl group), the poly organosiloxane containing an epoxy group, the poly organosiloxane containing an epoxy group at the terminal, etc. are mentioned. If necessary, a stabilizer heat improver, a filler, a pigment, a leveling agent, an epoxy diluent, a vinyl ether diluent, an adhesion improver to a substrate, an antistatic agent, an antifoaming agent, a non-reactive poly organosiloxane, and the like may be added to the silicone composition. It may be diluted with an organic solvent. It may also include polyurethanes, olefin copolymer materials, etc., with or without hydroxyl groups.

The thermosetting compound generates a tertiary base net structure throughout the pressure-sensitive adhesive according to a heat polymerization initiator subjected to a heat treatment of 50 to 150 ^° C. and lowers the adhesive force. Therefore, as the heat-curable pressure-sensitive adhesive (pressure-sensitive adhesive + monomer or oligomer + initiator), a low molecular weight compound or oligomer having at least two or more photopolymerizable carbon-carbohydrate double bonds in a molecule that can be three-dimensionally networked is preferable. Acrylate compounds, urethane acrylate oligomers and the like.

Non-limiting examples of acrylate compounds include trimethol propanetri acrylate, tetramethyrol methane tetraacrylate, pentaerythritol triacrylate, pentaestritol tetra acrylate, zipentaerythritol monocidoxykispenta-acrylic Leto, zepenaerythritolhekisaacrylto or 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polystyrene glycol diacrylate, oligo ester acrylate and the like.

The urethane acrylate oligomer includes polyol compounds such as polyester type or poly ether type, and isocyanate compounds. An organic peroxide derivative and an azo polymerization initiator are used as the heating polymerization initiator, but the use of the organic peroxide derivative is preferable because nitrogen is generated when the azo polymerization initiator is heated.

The heat-expandable pressure-sensitive adhesive is prepared by including a heat-peelable pressure-sensitive adhesive composition and an acrylic pressure-sensitive adhesive, the heat-peelable low-film composition is a vinyl butyral group (unit repeating 3 ~ 600), vinyl acetate group (unit repeating 1 ~ 80), vinyl alcohol The group (unit repeat is 4 ~ 700) has a polymer polymerized, it may further include an acrylic crab adhesive.

Organic crystal refers to an organic material which may have a crystalline form at a temperature below the melting point, and the adhesive forms crystals within the operating temperature range, but reduces the gel content of the adhesive to improve wettability to the substrate, and the like. The adhesion can be improved by the action of. In addition, when the temperature reaches the melting point of the organic crystals exceeding the operating temperature range, the organic crystals dissolve and move to the interface between the substrate and the adhesive to greatly reduce the adhesive strength of the adhesive and the substrate so that they can be easily peeled off.

Non-limiting examples of such organic crystals include 3- (hydroxyphenyl phosphinyl) propanoic acid, 9,10-dihydroxy-9oxa-10-phosphafaphenesrene-10-oxide, tris (3-hydroxypropyl Phosphine oxide, aromatic polyphosphate ester oligomer, triphenylphosphate, bisphenol A, meta-terphenyl and the like.

Thermal blowing agents can be applied to materials that are easily vaporized, such as isobutane, propane, pentane, and the like, such as vinylitene chlorite-acrylonitrile copolymer, polyvinyl alcohol, polyvinylbutyral, polymethylmethacrylate, polyacrylonitrile, poly It may be a thermally expandable microsphere encapsulated by forming an envelope with at least one material selected from the group consisting of vinylidene chloride and polystyrene. The thermally expandable microspheres may have a size of 1 to 100 μm, but is not limited thereto.

When the thermal foaming agent is added to the pressure-sensitive adhesive, gas is released when the heating temperature exceeds the allowable operating temperature range in which the pressure-sensitive adhesive is used and the foaming temperature of the thermal foaming agent is released. This decrease can cause the pressure sensitive adhesive to naturally peel off from the substrate. The thermal foaming agent is not particularly limited as long as the foaming start temperature at which the gas starts to be released is higher than the allowable operating temperature of the product in which the adhesive is used. However, the thermal foaming agent may be peeled off when the foaming start temperature is low. The heating temperature required for peeling becomes too high and may adversely affect other components. Thermal foaming agents that can be used can be broadly classified into inorganic foaming agents and organic foaming agents. Non-limiting examples of inorganic foaming agents include carbonium carbonate, sodium bicarbonate, ammonium nitrate, sodium fluoride hydride, azide, and the like, and non-limiting examples of organic foaming agents include trichloromonofluoromethane and dichloromonofluoromethane. Azo compounds such as hydrofluorinated alkanes, azobisisobutyronitrile and azodicarbonamides, toluenesulfonylhydrazide and 4,4'-oxybis (benzenesulfonylhydrazide), allylbis (sulfonylhydra) Hydrazide compounds such as zide), semicarbazide compounds such as p-toluylenesulfonyl semicarbazide and 4,4'-oxybis (benzenesulfonyl semicarbazide), and N-N'-dinitroso And N-nitroso-based compounds such as pentamethylenetetramine. If necessary, by adding a known foaming aid can improve the foaming rate and lower the foaming temperature. At this time, the desorption method using the thermal foaming agent may rupture the microspheres containing the gas and reduce the adhesive force by heating, but the fragments of the pressure-sensitive adhesive may contaminate the substrate by the rupture. However, since it can be washed with a small amount of organic solvent, it can be easily accessed from the amount and method of solvent.

In the case of using a high boiling point plasticizer, the process may result in an improvement in adhesiveness (adhesiveness), and at a boiling point (boiling point) of 150 ^° C or higher, the plastic material may be vaporized in the pressure-sensitive adhesive, resulting in weakening of adhesive force and peeling. However, the use of a plasticizer having a boiling point lower than 150 ^° C. is undesirable because it may evaporate due to heat resistance and long-term use, and may contaminate other parts.

Non-limiting examples of high boiling point plasticizers that can be used include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalic acid, z-2-ethylhexyl phthalate, zisononyl phthalate, zisodecyl phthalate, dibutyl benzyl, butyl Phthalic acid compounds, such as futaryl butyl copper coreto, tori meric acid tri tributyl, tori meritz to acid tri-2-ethyl hexyl, tori meritz to acid tri-n-octyl, tori meritz to acid triisodecyl Earth acid compounds and the like. In addition, fatty acid dibasic acid ester compounds, phosphoric acid compounds, epoxy compounds, butyl oleate, chlorinated paraffin and the like can also be used as plasticizers.

The first binder and the second binder according to the present invention can be separated even by light irradiation without heat supply. Therefore, the 1st adhesive agent and the 2nd adhesive agent can use the UV curable adhesive which adhesive force falls by irradiation of light (for example, ultraviolet-ray (UV)). At this time, since the first substrate and the second substrate to be used together with the adhesive should be a substrate through which UV can pass, the first or second bonding agent is light-transmitting of the first substrate or the second substrate to be used together. It is preferable that it is a substance which has a light radiation sensitivity according to 透過 性. In particular, when using a UV-permeable substrate as the second substrate, the second bonding agent may be a UV-curable pressure-sensitive adhesive which additionally hardens by light irradiation to significantly reduce the adhesive force and peel off. At this time, the conventional adhesive can use the usual adhesive irrespective of the range of temperature, and a heat peeling type is preferable.

The bonding of the first substrate and the bonding of the second substrate may be performed by applying heat, pressure, or heat and pressure while using the above-described bonding agents. At this time, the temperature range is not particularly limited as long as it is higher than the adhesion lowering temperature of the binder used, the melting point or higher, and the pressure range is also not particularly limited. For example, at the time of joining, heat may be applied by melting to reduce the temperature after joining.

3) processing step of the sapphire substrate (see Fig. 3d)

The second surface of the sapphire substrate in the secondary conjugate resulting from step (3) is processed, such as grinding, lapping and polishing. At this time, the grinding process is to grind at a speed as fast as the target thickness of the sapphire substrate, and the lapping and polishing processes are then mirror-polished the ground surface. The reason why the back surface of the sapphire substrate should be mirror surface is to recognize the pattern of the light emitting diode part on the front surface through the back surface of the sapphire during the scribing and breaking process, which is a subsequent process. To do that.

The second substrate is fixed to the sapphire substrate until the grinding, lapping, and polishing process of thinly processing the sapphire substrate as in the prior art, while the first substrate is formed with the sapphire substrate until the unit chip is formed and then bonded to the lead frame. Since it exists in the bonded state, the sapphire substrate can be processed to have a thickness of 80 μm or less, preferably in the range of 5 to 80 μm, more preferably 40 μm or less, which is the limit of the conventional sapphire processing technology. As described above, the present invention can implement an increase in heat emission efficiency of the light emitting diode device by providing a sapphire substrate having a thickness thinner than that of the conventional sapphire substrate. Such a process may be illustrated in FIG. 3.

4) Removing the second substrate (see Figure 3e)

From the sapphire substrate-first substrate-second substrate assembly by applying the inherent physical properties only the second binder has, such as adhesion lowering temperature, melting point, sensitivity to light irradiation, selective solvent use or a mixture thereof The second substrate can be easily separated.

That is, 1) to the first bonding agent (T ₁₎ or the second bonding agent (T _2), the adhesive strength decreases over temperature (heating (cooling to below) having) or; 2) selectively irradiating the first binder or the second binder; 3) use a solvent in which the first binder or the second binder does not dissolve simultaneously but selectively dissolves respectively; Or 4) at least one method selected from the group consisting of 1), 2) and 3) can be used simultaneously. In particular, the second sikidoe bonding agent temperature increase in the adhesive strength lowered temperature (T ₂₎ at least has, the adhesive force lowering the temperature of the first bonding agent (T ₁₎ to an elevated temperature to not higher than, or the second adhesive force lowering the temperature of the bonding agent (T ₂₎ sikidoe cooled below, it is preferable to cool the adhesive strength to decrease the temperature (T ₁₎ of at least one binder.

For example, in the separation, the second substrate is separated by applying heat, and then the temperature is lowered. At this time, the remaining bonding material adhering to the surface is melted using an organic solvent such as alcohol or acetone. Even after being separated, the sapphire substrate is fixed as it is by the first substrate.

5) Unit chip separation step (see Fig. 3f)

If necessary, the mirrored sapphire substrate surface can be scribed, and the first substrate can be selectively diced or scribed. After breaking, it is separated into unit chips. If necessary, using a first diced or scribed first substrate, the sapphire substrate is bonded to the sapphire substrate to be aligned with the part to be separated, and then the sapphire substrate is processed, followed by scribing only the sapphire substrate surface and then breaking. Can be separated into unit chips. In general, scribing refers to the operation of drawing a line on the wafer surface with a pointed and high-strength diamond tip, and breaking refers to the operation of impacting and cutting along the line drawn in the scribing. .

6) Bonding to the Leadframe and Separating the First Substrate

After bonding the second surface of the processed sapphire substrate to the lead frame, the first substrate is separated. Bonding the sapphire substrate and the lead frame may be a material that is easily known in the art, and non-limiting examples thereof include silver paste, solder, and the like. In addition, if necessary, a thin metal film may be deposited on the surface of the sapphire substrate to improve bonding strength, and a low melting point alloy of In and Sn may be used as a bonding metal. If the metal thin film is deposited, at least before the breaking step is performed. It is appropriate.

By proceeding similarly to the second substrate separation method of step 5), it is possible to easily separate the first substrate from the bonded body of the sapphire substrate and the first substrate attached on the lead frame. At this time, even if the first substrate is separated, since the sapphire substrate is already completely bonded to the lead frame, the structural stability of the sapphire substrate is maintained as it is.

7) wire bonding

Next, when the n-omic contact metal layer and the p-omic contact metal layer of the light emitting diode parts fabricated on the sapphire substrate are connected to an external power source through gold wire bonding, the front light emitting diode device as shown in FIG. Is produced (see FIG. 3G). In this case, the shape of the lead frame of FIG. 1 is a lamp type mainly used for fabricating a light emitting diode device for low output, and in the case of a high output, the shape of the lead frame is a surface mount type (SMD) or the like.

8) Molding Step

Subsequently, when a molding material such as epoxy, a fluorescent material or a molding material mixed with a phosphor is covered, the manufacturing of the light emitting diode device is completed (see FIG. 3G).

The light emitting diode element constructed as described above can be operated by the following principle. That is, when a specific voltage is applied through a wire connected to the external power source, the negative electrode is connected through the n-type conductive pad portion, the n-type ohmic contact metal, the n-type layer, the p-type conductive pad portion, the p-type ohmic contact metal, The anode is connected through the p-type layer to inject current. As a result, in the active layer, electrons and holes recombine with each other to emit light having an energy corresponding to a band gap or energy level difference of the active layer.

When using the sapphire substrate processing technology of the present invention presented above, it is possible to manufacture a top-emitting high-power LED having advantages such as a simple manufacturing process, low production cost, high mass production. In particular, since heat dissipation is improved and reliability of the device is secured, it may have strength in manufacturing application products such as light sources and lighting devices for LCD TVs, which are expected to form a huge market in the future. Due to the implementation of the processing technology of the sapphire substrate according to the present invention it can be a breakthrough turning point in the manufacture of high-power LEDs.

According to a preferred embodiment of the method of manufacturing the top-emitting LED device of the present invention using the sapphire processing technique described above, after the sapphire substrate on which the LED crystal structure is grown is placed on the lead frame, the positive electrode 11, 12) is manufactured by the method of forming and connecting them to an external power source, respectively, each process can be configured as follows.

(1) growing light emitting diode part on sapphire substrate

First, a sapphire substrate 10 in which an n-type layer, an active layer (aka light emitting layer), and a p-type layer are sequentially stacked is prepared using a method such as metal organic chemical vapor deposition (MOCVD). In this case, the n-type layer, the active layer, p-type layer may be formed using a conventional gallium nitride compound known in the art, such as GaN, GaAlN, InGaN, InAlGaN or a mixture thereof, and if necessary, these compound semiconductor layers and A buffer layer may be formed between the sapphire substrates.

(2) etching step

The p-type layer and the active layer corresponding to the predetermined region are dry etched to expose a portion of the upper surface of the n-type layer.

(3) n-omic contact metal forming step

An n-type ohmic contact metal is deposited to apply a predetermined voltage to the n-type layer surface exposed through the etching process.

(4) forming a p-omic contact metal or a translucent p-omic contact metal

After forming a light-transmissive p-omic contact metal by vacuum deposition on the surface of the p-type layer on the light emitting diode portion and performing heat treatment, a p-omic contact metal for wire bonding is formed to form a p-omic contact. For easier fabrication, after performing the etching step (2), a light-transmissive p-omic contact metal may be formed, followed by heat treatment, and then an n-omic contact metal and a p-omic contact metal may be simultaneously formed.

(5) bonding step of the first substrate (see Fig. 3b)

As described above, the light emitting diode portion grown on the sapphire substrate and the first surface of the first substrate are bonded using the first bonding agent.

(6) bonding step of the second substrate (see Fig. 3c)

As mentioned above, the 2nd surface of a 1st board | substrate and the 1st surface of a 2nd board | substrate are bonded together using a 2nd bonding agent.

(7) Processing (Polishing) Step of Sapphire Substrate Surface (Step 3D)

The sapphire processing technique of the present invention described above is processed to a desired thickness range.

(8) second substrate separation (see FIG. 3E)

As described above, the second substrate is separated by applying inherent physical properties of only the second binder, such as adhesion lowering temperature, melting point, sensitivity to light irradiation, selective solvent use, or a mixture thereof.

(9) unit chip separation step (refer to FIG. 3f)

According to the sapphire processing technology of the present invention described above, a unit light emitting diode chip is formed by scribing / breaking the bonded body of the first substrate and the processed sapphire substrate.

(10) Bonding to the Leadframe and Separating the First Substrate

A second surface (processing surface) of the sapphire substrate in the form of a unit chip is bonded to a lead frame for packaging a light emitting diode. A bonding agent known in the art may be used, for example, silver paste, solder, Sn-based low melting alloy thin film, or In-based low melting alloy thin film. Thereafter, as described above, the first substrate is removed.

(11) wire bonding and molding material processing step

After performing gold wire bonding for anode and cathode connection, a light emitting diode is fabricated by covering a molding material such as epoxy or a molding material in which phosphors are mixed.

The method of manufacturing the above-described light emitting diode device is merely a preferred embodiment, and the present invention is not limited thereto.

The present invention provides a light emitting diode device manufactured as described above. In this case, the light emitting diode device of the present invention includes not only a conventional light emitting diode device known in the art, for example, a blue nitride-based light emitting diode device, but also a light emitting diode device of all other wavelengths, and all light emitting diodes having a sapphire substrate as one component. Applicable to the device.

The present invention also provides a light emitting device comprising a light emitting diode device manufactured according to the above method. The light emitting device includes all light emitting devices including light emitting diode elements. Examples of the light emitting device include a lighting device, a display unit, a germicidal lamp, and a display unit.

Hereinafter, the present invention will be described in more detail by explaining preferred embodiments of the present invention. However, the present invention is not limited by the following examples.

[Examples 1 to 11. Fabrication of Light-Emitting Diode Device]

Example 1

1-1. Sapphire Substrate and Silicon Wafer Bonding

A 2 inch sapphire substrate on which a GaN type light emitting diode portion was formed was bonded to a 2 inch silicon wafer having a thickness of 250 μm using wax as the first bonding agent. At this time, the wax (Shift wax) is put on the melted part, and then the wax is heated to 120 ° C. to make a liquid state, and then the surface of the light emitting diode part of the silicon wafer and the sapphire wafer is bonded. It was bonded by pressing at 占 폚.

1-2. Bonding with ceramic blocks

Subsequently, it heated up to 70-100 degreeC using the side chain crystalline polymer and a pressure sensitive adhesive as a 2nd bonding agent, and bonded it to the ceramic block. The surface of the ceramic block on which the second bonding agent is attached and the back surface of the silicon wafer on which the sapphire substrate is bonded are bonded together, and then cooled to room temperature while pressing in a press to complete adhesion to the ceramic block.

1-3. Second surface (rear) processing of sapphire substrate

The back surface of the sapphire substrate was ground in one step using a diamond plate and water, and then in two steps, an oil containing CMP slurry was ground. Thereafter, in three steps, the sapphire substrate was slowly ground to an oil containing CMP slurry, and the sapphire substrate was processed to a thickness of about 35 μm.

1-4. Ceramic block removal

In order to remove a ceramic block, the ceramic block was again heated to the temperature of about 70-100 degreeC, and the ceramic block was isolate | separated from the sapphire substrate and the silicon wafer assembly.

1-5. Unit light emitting diode chip manufacturing and leadframe junction

Subsequently, the surface of the sapphire substrate was scribed and broken to cut out to the size of the unit light emitting diode chip. The sapphire substrate surface of the cut light emitting diode unit chip was bonded to the lead frame using silver paste. The temperature at the time of joining was about 110 degreeC.

1-6. Silicon Wafer Removal and Light Emitting Diode Fabrication

After the IPA was added to the leadframe, the wax was melted and the silicon wafer was removed and cleaned by an additional IPA treatment. Gold wire bonding was performed on the exposed LED structure and molding to complete the fabrication of the LED device.

[Examples 2 to 11]

A light emitting diode device was manufactured in the same manner as in Example 1, except that the first bonding agent and the second bonding agent were used as in Table 1 below.

Example 1st binder 2nd binder 2 Wax; Adhesion by heating to 120 ° C .; Peel while heating to 120 ^o C and dissolving with IPA. Use of thermosetting adhesives; Adhesion is reduced by curing the pressure-sensitive adhesive by heating between 70 ~ 120 ℃ 3 Same as Example 2 Thermal foaming agent; The thermal foaming agent is included in the pressure-sensitive adhesive to foam when heated at 70 to 100 ° C. to facilitate desorption. 4 Use of thermosetting adhesives; Including the existing pressure-sensitive adhesive + thermosetting compound, the adhesive is cured between 100 ~ 150 ^o C, the adhesive strength is reduced Side chain crystalline polymer + pressure-sensitive adhesive; Heat peel type between 70 ~ 100 ℃ 5 Thermal foaming agent; Including the thermal foaming agent having a foaming start temperature of 100 ~ 200 ^° C in the pressure-sensitive adhesive to facilitate foaming when heated. It is preferable that the foaming start temperature is 10 ^o C or higher than the pressure-sensitive adhesive operating temperature. Thermal foaming agent; The foaming start temperature in the pressure-sensitive adhesive is included 70 ~ 120 ℃ thermal foaming agent to foam when heated to facilitate the desorption. It is preferable that the foaming start temperature is 10 ^o C or higher than the pressure-sensitive adhesive operating temperature. 6 Same as Example 5 Side chain crystalline polymer + pressure-sensitive adhesive; Heat peelable between 70 and 100 ^o C 7 Same as Example 5 Heated foam adhesive; By heating it to 100 ~ 120 ^o C, the adhesive itself is thermally expanded or foamed so that desorption occurs. 8 Heated foam adhesive; By heating it to 100 ~ 120 ^o C, the adhesive itself is thermally expanded or foamed so that desorption occurs. Side chain crystalline polymer + pressure-sensitive adhesive; Heat peelable between 70 and 100 ^o C 9 High boiling point plasticizer included; Adhesion decreases above 150 ^o C, including plasticizers with boiling point above 150 ^o C, resulting in desorption. Side chain crystalline polymer + pressure-sensitive adhesive; Heat peel type between 70 ~ 100 ℃ 9 Same as Example 9 Thermal foaming agent; The foaming start temperature in the pressure-sensitive adhesive is included 70 ~ 120 ℃ thermal foaming agent to foam when heated to facilitate the desorption. 10 Use of organic crystals; Organic crystals with melting points of 120 ~ 150 ^o C are used to reduce the cohesion by giving heat above 120 ^o C. Use of organic crystals; Adhesion is reduced only by heat of 70 to 120 ℃ using an organic crystal having a melting point of 70 ~ 120 ℃.

The present invention relates to a method for minimizing the thickness of a sapphire substrate used in the fabrication of a top light emitting diode, and is particularly useful in the manufacture of high power light emitting diodes since heat dissipation is improved compared to the top light emitting structure according to the prior art. Can be.

Claims (18)

(a) a first substrate made of a material capable of performing a braking process; And (b) A bonded body comprising a sapphire substrate on which a light emitting diode portion is grown on a first surface, wherein the first surface of the first substrate and the light emitting diode portions of the sapphire substrate are bonded to each other by a bonding agent. The conjugate of claim 1, wherein the first substrate is the same as or larger than the size of the sapphire substrate. The bonded body of claim 1, wherein the first substrate is a silicon wafer or a ceramic wafer. The joined body according to claim 1, wherein a second surface of the sapphire substrate is formed with a mirror surface. The bonded body of claim 1, wherein the sapphire substrate has a thickness in the range of 5 to 80 μm. The unit chip separated after processing the thickness of the sapphire substrate in the conjugate of any one of claims 1 to 5 in the range of 5 to 80㎛. In the manufacturing method of a light emitting diode device comprising a light emitting diode portion grown on a sapphire substrate, (a) bonding the light emitting diode portion grown on the sapphire substrate and the first surface of the first substrate using a first bonding agent; (b) joining the second surface of the first substrate and the first surface of the second substrate in the resulting bonded body of step (a) using a second bonding agent having a different adhesive force lowering property than the first bonding agent; ; (c) after processing the second surface of the sapphire substrate in the resulting conjugate of step (b), separating the second substrate; (d) separating the bonded body from which the second substrate is separated into unit chips; And (e) bonding the second surface of the processed sapphire substrate in the unit chip to a lead frame, and then separating the first substrate Method of manufacturing a light emitting diode comprising a. The method of claim 7, wherein the first bonding agent and the second bonding agent are materials capable of performing a processing process of the sapphire substrate in a state of being bonded to the sapphire substrate, and have different adhesion force lowering temperatures. The adhesive force lowering temperature difference of the first bonding agent (T ₁ ) and the second bonding agent (T ₂ ) is | T ₁ -T ₂ | ≧ 10 ° C. 10. The method of claim 9, wherein the first binder and the second binder are cold peelable or heat peelable materials which lose adhesive strength at or below a specific temperature. The manufacturing method of Claim 7 whose melting point of the said 1st binder is 80-220 degreeC, and the melting point of the 2nd binder is 40-120 degreeC. The method of claim 7, wherein the first binder and the second binder are at least one selected from the group consisting of side chain crystalline polymers, pressure sensitive adhesives, thermal foaming agents, heated foaming adhesives, high boiling point plasticizers, and organic crystals. The method of claim 7, wherein the first bonding agent or the second bonding agent is a material having a light radiation sensitivity according to the light transmittance of the first substrate or the second substrate to be used together Manufacturing method. The method of claim 13, wherein the light radiation sensitive material is a UV curable pressure sensitive adhesive in which curing occurs by light irradiation. The method of claim 7, wherein the first binder and the second binder are substances dissolved in different solvents. 8. A process according to claim 7, wherein the bonding in steps (b) and (c) is carried out by heating, pressurizing or heating and pressurizing. 8. The method of claim 7, wherein separation of the first substrate and the second substrate in steps (c) and (e) 1) to the first bonding agent (T ₁₎ or the second bonding agent (T _2), the adhesive strength decreases over temperature (heating (cooling to below) having) or; 2) selectively irradiating the first binder or the second binder; 3) use a solvent in which the first binder or the second binder does not dissolve simultaneously but selectively dissolves respectively; or 4) The production method characterized in that the separation using at least one method selected from the group consisting of 1), 2) and 3) at the same time. 18. The method of claim 17, wherein in step (e) the separation of the second substrate is Raise the temperature above the pressure drop temperature T _{2 of} the second bonding agent, and raise the temperature below the pressure drop temperature T ₁ of the first bonding agent, or The adhesive force decreases the temperature of the second bonding agent (T ₂₎ sikidoe cooled below, the adhesive strength decreases the temperature of the first binder preparation is cooled to more than (T _1).

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