High efficient reflective metal layer of light emitting diode

High-efficiency reflective layer light-emitting diode and manufacturing method thereof

Field of invention:

The present invention relates to a high-efficiency light-emitting diode (Light Emitting Diode; LED) structure, in particular to a III-V compound semiconductor light-emitting diode structure and a manufacturing method thereof, wherein the light-emitting diode structure has high reflectivity The metal mirror is in it to prevent the generated light from being absorbed by the substrate.

Background of the invention:

The traditional aluminum gallium indium phosphide light-emitting diode has a Double Heterostructure (DH), and its structure is shown in Figure 1. From bottom to top, they are: substrate ohmic contact electrode layer 1, an n-type arsenic Gallium (GaAs) substrate (Substrate) 1, an n-type (Al_xGa_1-x)_0.5In_0.5P under the cladding layer 3, a (Al_xGa_1-x)_0.5In_0.5The active layer of P5, a p-type (AlxGa_1-x)_0.5In_0.5The cladding layer 7 above P, and a p-type high energy gap current spreading layer (Current Spreading Layer) 9, the material of this layer can be gallium phosphide, gallium arsenide phosphate, indium gallium phosphide, tin oxide or arsenide Aluminum gallium and so on. However, because the energy gap of the gallium arsenide substrate 1 is small, the light emitted by the active layer 5 and the light toward the gallium arsenide substrate 1 will all be absorbed by the gallium arsenide substrate 1. Therefore, in terms of the quantum efficiency of the luminescence of the aluminum gallium indium phosphide light-emitting diode, its efficiency is very low. In addition, the thermal conductivity of gallium arsenide is only about 44W/m-°C. Therefore, with such a small thermal conductivity of gallium arsenide, it is not enough to dissipate all the heat energy of the light-emitting diode.

In order to overcome the shortcomings of the above substrate light absorption. Traditionally, there are some documents exposing LED technology, but these technologies have their shortcomings and limitations, such as Sugawara et al. published in [Appl. Phys Lett. Vol. 61,1775-1777(1992)] and disclosed a method of adding a Distributed Bragg Reflector (DBR) on the gallium arsenide substrate 1, which emits light Please refer to Figure 2 for the structure of the diode. Since the structure is similar to that in Figure 1, some of the films with similar functions are marked with the same figure numbers. In Figure 2, Sugawara et al. added the dispersed Bragg reflective layer 2 to be formed in the gallium arsenide substrate 1 and the lower cladding layer 3 to reflect light toward the gallium arsenide substrate 1. A blocking area 10 is added to enhance the current distribution. However, the reflection efficiency of the DBR layer 2 to the aluminum gallium indium phosphide light-emitting diode is only about 80%. In addition, the reflection characteristics are related to the reflection angle. The DBR layer 2 can be very efficient only for normal incidence or near normal incidence to the gallium arsenide substrate 1. Therefore, the DBR layer 2 has a limited improvement effect on the light quantum efficiency. To make the DBR layer 2 achieve high reflectivity, the epitaxial time needs to be longer to control the thickness of each single layer. As a result, production capacity cannot be increased.

Another example is published in [Appl. Phys Lett. Vol. 64, No. 21, 2839, (1994) by Kish et al., titled "Very high-efficiency semiconductor wafer-bonded transparent-substrate(Al_xGa_1-x)_0.5In_0.5P/GaP", reveals a transparent-substrate (TS) (Al_xGa_lx)_0.5In_0.5P/GaP light-emitting diodes. Please refer to the schematic diagram shown in Figure 3. Among them, Kish et al. replaced the gallium arsenide substrate with a transparent substrate TS 13. TS AlGaInP LED is based on the use of hydride vapor phase epitaxy (Hydride vapor phase epitaxy) epitaxy; HVPE) A p-type gallium phosphide (GaP) window layer 11 with a relatively thick thickness (about 50 μm) is formed on the epitaxy layer 12 of the light-emitting structure. The epitaxial layer of the light-emitting structure contains 0.75m thick p-type Al_0.5In_0.5P coating layer 3 / active layer (Al_xGa_1-x)_0.5In_0.5P5/1μm thick n-type Al_0.5In_0.5The P cladding layer 7 is formed on the temporary n-type gallium arsenide substrate. After the p-type gallium phosphide (GaP) window layer 11 is formed, a conventional chemical etching method is used to selectively remove the n-type gallium arsenide (GaAs) substrate. Then the exposed n-type (Al_xGa_1-x)_0.5In_0.5The P lower cladding layer 3 is bonded to the n-type gallium phosphide substrate TS 13 with a thickness of about 8-10 mils. As far as the luminous brightness is concerned, the TS AlGaInP LED prepared in this way is more than twice as bright as the traditional Absorbing-Substrate (AS) AlGaInP LED. However, the disadvantage of this TS AlGaInP LED is that the manufacturing process is too complicated, and the bonding interface usually has a high resistance characteristic of non-ohmic contact. Therefore, it is impossible to obtain a high production yield and it is difficult to reduce the manufacturing cost.

Another conventional technique, please refer to the schematic diagram in Fig. 4, is a light-emitting diode disclosed in US Patent No. 5,917,202 obtained by Haitz et al. After the light-emitting diode epitaxial layer 40 (including the active layer 41 and the n-type GaP layer 45p and the p-type GaP layer 43 is formed, a metal reflective layer 47 and n Electrodes 47a (which can also be made of the same material as the reflective metal layer 47 to simplify the procedure) are placed on its upper and lower sides, and then pulse lasers are used to heat the reflective metal layer 47 at certain points to make it and the p-type GaP layer 43 And the n electrode 17a and the n-type GaP layer 45 each form a number of alloy dots 49. The alloy dots are distributed in dots (the diameter of each dot and the distance between the dots and the dots are determined by the current area that each dot can spread). use These alloy points 49 can form ohmic contacts without passing the wafer through a furnace high temperature process. However, the production capacity must be determined by the laser programming speed, so it cannot be increased, and any subsequent high-temperature processes are not allowed. For another embodiment of Haitz et al., please refer to Fig. 5, the diode epitaxial layer 50 is combined on a transparent substrate 52, and then a dielectric layer 53 is formed on the transparent substrate 52, and then by micro The shadow and etching technique forms a channel 54a, and then an ohmic contact metal layer 54 is formed to fill the channel. So that the current of the n-electrode and the p-electrode can penetrate to the reflective metal layer 56 formed on the dielectric layer 53. In addition to the complexity of the manufacturing process, the non-conductivity and non-conductivity of the dielectric layer 53 will deteriorate the characteristics of the light-emitting diode chip under high-temperature processing or high-current operation.

The purpose and summary of the invention:

One objective of the present invention is to provide a high-efficiency light-emitting diode structure with a reflective metal layer.

Another object of the present invention is to provide a structure for preventing the reaction between the reflective metal layer and the p-type ohmic contact layer due to annealing. In addition, the ohmic contact method between the transparent conductive oxide layer and the light-emitting diode epitaxial layer in the present invention Four embodiments are also provided.

Another object of the present invention is to provide a structure that prevents the adhesive layer from reacting with the reflective metal layer. To further prevent the reflective metal layer from reacting with the adjacent layer.

The present invention provides a high-efficiency light-emitting diode structure. The structure at least includes a light-emitting diode epitaxial layer structure grown on a temporary substrate with matching lattice constants, a transparent conductive oxide layer and highly reflective metal The layers are then sequentially formed on the p-type transparent ohmic contact layer of the epitaxial layer. Finally with a silicon On the substrate, a metal conductive heat dissipation substrate is deposited on the upper and lower sides, and then a solder layer or metal or metal silicide is used to adhere the highly reflective metal layer and the silicon substrate together. Then remove the temporary substrate. And forming an n electrode. Annealing is performed to make the n-electrode and the light-emitting diode epitaxial layer form a good ohmic contact. In addition, in order to prevent the adhesive layer from reacting with the reflective metal layer, a conductive oxide layer can also be formed on the reflective metal layer first.

In addition, the ohmic contact between the transparent conductive oxide layer and the light emitting diode epitaxial layer can be completed by the following four embodiments. In the first embodiment, ohmic contact dots or mesh layers are formed in the transparent conductive oxide layer at the interface of the light-emitting diode epitaxial layer to evenly distribute the current, and then injected into the light-emitting diode epitaxial layer. In the second embodiment, a thin gallium arsenide epitaxial layer doped with high-conductivity impurities is used between the light-emitting diode epitaxial layer and the transparent conductive oxide layer, so that the transparent conductive oxide layer becomes thinner first. The gallium arsenide layer first forms a good ohmic contact to make the current distribution uniform.

In the third embodiment of the present invention, a transparent metal layer is used as a good ohmic contact between the transparent conductive oxide layer and the light emitting diode epitaxial layer. In the fourth embodiment, a plurality of ohmic contact channels are formed in the transparent conductive oxide layer, so that the current is evenly distributed in the light-emitting diode epitaxial layer.

Detailed description of the invention:

As mentioned earlier, the conventional use of DBR as a reflective layer light-emitting diode can reflect part of the light toward the substrate, but after all, there is a problem with the angle of incidence, which reduces the brightness. However, a reflective metal layer is used instead of the DBR layer. There is no light incident angle problem, but there is no need for any high-temperature process problems after the reflective metal layer is in direct contact with the III-V compound light-emitting diode epitaxial layer. Although HP has proposed another solution, that is, using a dielectric layer to isolate the direct contact between the reflective metal layer and the III-V compound light-emitting diode epitaxial layer, so that any process steps including high-temperature processes can be performed. But the current can only provide a current path through a plurality of conductive holes in the dielectric layer, and there is no other way. As a result, not only the complexity of the process steps is increased, but the dielectric layer itself cannot withstand large currents due to its poor thermal conductivity, and the power is limited.

Therefore, the present invention will provide three new light-emitting diode structure embodiments to solve the above-mentioned shortcomings of traditional light-emitting diodes. The detailed description is as follows.

First, please refer to the cross-sectional schematic diagram of the epitaxial structure layer 1000 of the light emitting diode shown in FIG. 6A, which includes an n-type gallium arsenide (GaAs) substrate 100 and an etching stop layer ( Etching Stop Layer) 102, an n-type aluminum gallium indium phosphide (Al_xGa_1-x)_0.5In_0.5The cladding layer 104 under P, in which the aluminum content ranges from 50 to 100%, is an undoped aluminum gallium indium phosphide (Al_xGa_1-x)_0.5In_0.5P active layer (Active Layer) 106, where the aluminum content ranges from 0-45%. When the aluminum content x=0, the composition of the active layer is Ga_0.5In_0.5P, and the wavelength λd of the light emitted by the light-emitting diode is about 635nm, which is about the red light range. A p-type (Al_xGa_1-x)_0.5In_0.5The Cladding layer 108 on P, in which the aluminum content can also range from 50 to 100%, is a p-type Ohmic Contact Epitaxial Layer 110.

In addition, the material of the etch stop layer 102 can be any III-V compound semiconductor. However, the lattice constant needs to be matched with the gallium arsenide substrate 100 to reduce the occurrence of misalignment. Another point is to use eclipse Engraved mixing agent such as: 5H₃PO₄:3H₂O₂:3H₂O or 1NH₄OH:35H₂O₂) During etching, the etching rate needs to be lower than the etching rate for the gallium arsenide substrate 100. In addition, the etching stop layer 102 also needs a high carrier concentration to reduce the ohmic contact resistance. Typically, the carrier concentration is higher than 1×10¹⁸/cm³. In the present invention, the preferred material of the etching stop layer 102 can be indium gallium phosphide (InGaP) or aluminum gallium arsenide (AlGaAs).

The p-type ohmic contact epitaxial layer 110 should be selected from a material that has a high degree of light transmittance to the active layer 106, and this layer of material is therefore referred to as the transparent ohmic contact layer 110 hereafter. In other words, the transparent ohmic contact layer 110 is selected from materials having an energy band gap larger than the active layer 106, and is doped with a high carrier concentration to facilitate the formation of ohmic contacts. According to the above requirements, the transparent ohmic contact layer 110 can be selected from materials that meet the above requirements among III-V compound semiconductors. For example, if the wavelength range of the light emitted by the active layer 106 is from 590 nm to 650 nm, then aluminum gallium arsenide (AlGaAs) or gallium arsenide phosphorous (GaAsP) can be selected in this way. If the wavelength is around 560nm and below, gallium phosphide (GaP) can be selected. In addition, the carrier concentration of the transparent ohmic contact layer 110 is higher than 1×10¹⁸/cm³。

Subsequently, a p-type ohmic metal contact pattern layer 112 with a dot or mesh pattern is formed on the transparent ohmic contact layer 110. The material of the p-type ohmic metal contact pattern layer 112 can be a metal layer of this type such as Au-Be, Au-Zn or Cr-Au. In order to promote the current injected by the p-electrode (described later) to be uniformly distributed through these ohmic contact dots or mesh layers 112. The number of the ohmic contact dots or grid layers 112 depends on the horizontally spreading surface through these dots or grids, and the spreading surface is in contact with the transparent ohmic contact The thickness of the layer 110 and its resistance value are determined. For example, if the transparent ohmic contact layer 110 is thick, the dot pitch of the ohmic contact dots 112 can be allowed to be sparse. Conversely, it is denser. In addition, the smaller the resistance of the transparent ohmic contact layer 110 is, the larger the lateral spreading surface of each ohmic contact dots is, the larger the number of the ohmic contact dots or the grid layer 112 can be reduced. In addition, the higher the coverage of the p-type ohmic metal contact pattern layer 112 will reduce the light output, but it will also relatively reduce the forward voltage value of the light-emitting diode. Therefore, considering the gains and losses of both light output and contact resistance, the coverage of the p-type ohmic metal contact pattern layer 112 is preferably less than 10%.

The dot-shaped or mesh-shaped p-type ohmic metal contact layer 112 can be formed in the following order. One way is to first form a p-type ohmic metal contact layer, secondly form a photoresist pattern thereon, then apply an etching technique to form the p-type ohmic metal contact pattern layer 112, and finally remove the photoresist pattern. Another method is to first form a photoresist pattern on the transparent ohmic contact layer 110, secondly form a p-type ohmic metal contact layer, and then apply adhesive tape to remove the p-type ohmic metal contact layer with poor adhesion to form The p-type ohmic metal contacts the pattern layer 112, and finally the photoresist pattern is removed.

Subsequently, the light-emitting diode structure is further subjected to a high-temperature annealing step of 350-600° C. to reduce the contact resistance value. Then, a transparent conductive oxide layer 114 and a highly reflective metal layer 116 are successively formed on the transparent ohmic contact layer 110, as shown in the figure, of course including covering the p-type ohmic contact pattern layer 112 therein. The transparent conductive oxide layer 114 is an oxide layer with high conductivity and good light penetration according to the method of the present invention, and will not interfere with the The transparent ohmic contact layer 110 and the high-reflectivity metal layer 116 react. For example, like In₂O₃, SnO₂, CdO, ZnO, ITO (Indium Tin Oxide), CTO (Cadmium Tin Oxide), CuAlO₂, CuGaO₂And SrCu₂O₂. They are all candidates for the transparent conductive oxide layer 114 that can be selected. As for the high-reflectivity reflective metal layer 116, it can be selected from aluminum, gold, silver and the like. The three kinds of metal layers are all selected from metal layers with high reflectivity. At a wavelength of 560 to 650 nm, the reflectivity of the reflective metal layer 116 is about 90% or more. The main improvement of the present invention can be seen because the present invention uses the transparent conductive oxide layer 114 between the high-reflectivity metal layer 116 and the transparent ohmic contact layer 110. This can prevent the reaction between the reflective metal layer 116 and the transparent ohmic contact layer during the high temperature annealing process. Generally speaking, the materials selected for the reflective metal layer 116, aluminum, gold, and silver, will react with almost all III-V compounds. And the higher the annealing temperature, the more serious the situation. If the two react, the light reflectivity of the reflective metal layer 116 will be obviously damaged. Adding an inert layer: the transparent conductive oxide layer 114 can completely avoid the reaction between the reflective metal layer 116 and the transparent ohmic contact layer 110. Therefore, the reflective metal layer 116 can withstand high-temperature annealing without the problem of deterioration of reflectivity.

Then, the aluminum gallium indium phosphide light-emitting diode epitaxial layer 1000 is adhered to the substrate 125 with high thermal conductivity and conductivity. There are many semiconductors, ceramics, and metal materials that are used, such as silicon substrates, silicon carbide substrates, aluminum nitride, copper and aluminum are all excellent candidates for the electrical and thermal conductivity substrate materials, due to their good heat dissipation. , So it can be subjected to higher current. Especially for silicon substrates, not only are they cheap, but they can be polished, etched, or cut. It's easy, so a silicon substrate is a better choice. As shown in FIG. 6B, first, the silicon substrate 120 must be doped with conductive impurities or directly doped with high-concentration conductive impurities. Subsequently, a metal layer is deposited on the upper and lower sides of the silicon substrate 120 to form the ohmic contact metal layer 122. Subsequently, one of the ohmic contact metal layers 122 uses a metal adhesion layer 124 to adhere the metal reflective layer 116 on the aluminum gallium indium phosphide light-emitting diode epitaxial layer and the ohmic contact metal layer 122 together. The material of the metal adhesion layer 124 must have high adhesion strength and current conductivity. For example, it can be selected from solder, low-temperature metals or metal silicides such as PbSn, AuGe, AuBe, AuSi, Sn, In, AuIn, and PdIn. Good choice. In order to prevent the metal adhesion layer 124 and the reflective metal layer 116 from reacting during the high-temperature annealing process, a diffusion barrier layer 119 can be selectively deposited on the reflective metal layer 116 first. The diffusion barrier layer 119 may be selected from indium tin oxide ITO, cadmium tin oxide CTO, or zinc oxide. Or other refractory metal layers with high melting point can be used, such as tungsten, tungsten nitride, molybdenum and some high temperature metal silicides can be used. Of course, if the diffusion barrier layer 119 is not deposited first, the reflective metal layer 116 may be thicker during deposition. In addition, please note that although the metal adhesion layer 124 is formed on the ohmic contact metal layer 122 as an example in FIG. 6B, it does not limit the scope of the present invention, because the metal adhesion layer 124 can also be directly formed on the ohmic contact metal layer 122. It can be on the reflective metal layer or on the diffusion barrier layer 119. In addition, the metal adhesion layer 124 may not be required, as long as the ohmic contact metal layer 122 is a low melting point metal or alloy, but after adhesion, it must be at least resistant to the wire bonding process temperature, so that the reflective layer 116 It adheres firmly to the substrate 120.

After bonding, use grinding or chemical etching mixture such as 5H₃PO₄:3H₂O₂:3H₂O or 1NH₄OH:35H₂O₂) Or reactive ion etching (RIE) to remove the opaque n-type gallium arsenide substrate 100 and stay on the etching stop layer 102. Subsequently, an n-type ohmic contact layer 130 is formed on the etching stop layer 102 as an electrode, and the result is as shown in FIG. 6C. Of course, subsequent annealing is required to reduce the ohmic contact resistance, so as to complete the production of aluminum gallium indium phosphide light-emitting diodes with vertical current conduction and good heat dissipation capabilities. The wavelength range of the aluminum gallium indium phosphide light-emitting diode completed according to the process of the present invention is about 585 to 630 nm, and the lumen illuminance is about 30 lumens/W. In addition, the brightness increases with the injected current, and the current can reach more than 100mA. It proves that silicon as a substrate material is indeed better than a substrate using gallium arsenide. Although the above embodiments use aluminum gallium indium phosphide light-emitting diodes as examples, it does not represent a restriction on the applicable diodes of the present invention. Types, such as aluminum gallium arsenide (AlGaAs) light-emitting diodes, indium gallium arsenide phosphorous (InGaAsP) light-emitting diodes, aluminum gallium indium nitride (AlGaInN) light-emitting diodes or vertical cavity surface-emitting lasers A vertical cavity surface emitting laser can also be applied.

In the first preferred embodiment, it has been mentioned that the transparent conductive oxide layer is formed between the reflective metal layer 116 and the light-emitting diode epitaxial layer 1000, which can prevent the light-emitting diode epitaxial layer from being caused by subsequent high-temperature processes. The reaction of 1000 with the reflective metal layer 116. The ohmic contact mesh or dot layer 112 can make the current injected into the transparent conductive oxide layer spread evenly on the light-emitting diode epitaxial layer 1000 through the ohmic contact mesh or dot layer 112. Instead of being blocked by the energy barrier between the junction of the transparent conductive oxide layer 114 and the light emitting diode epitaxial layer 1000.

The above-mentioned light-emitting diode epitaxial layer 1000 and the transparent conductive oxide layer 114 can also be changed as follows. Please refer to the second embodiment of the present invention, as shown in FIG. 7. A thin film layer with a small energy gap relative to the light-emitting diode epitaxial layer is formed between the ohmic contact conductor layer of the light-emitting diode epitaxial layer 1000 and the transparent conductive oxide layer on the light-emitting diode epitaxial layer A transparent conductive oxide layer is formed on top to promote good ohmic contact between the transparent conductive oxide layer and the light emitting diode epitaxial layer. Taking the InGaAsP light-emitting diode epitaxial layer as an example, the thin film layer with a small energy gap can be a thin layer of gallium arsenide 113g or a thin layer of phosphorous gallium arsenide (the phosphorus content is 20 to 30%) 113g One of them.

Therefore, on the diode epitaxial layer 1000 including the temporary substrate 100, a thin layer of gallium arsenide 113g or a thin layer of phosphorous gallium arsenide (with a phosphorus content of 20 to 30%) 113g is first formed, and then Then, a transparent conductive oxide layer 114 and a reflective metal layer 116 are sequentially formed, and the subsequent steps of the reflective metal layer 116, adhesion of the conductive and thermally conductive substrate, removal of the temporary substrate 100, formation of the n-electrode 130, and annealing are as described above. As mentioned above, due to the small energy gap of gallium arsenide or phosphorous gallium arsenide, there is a problem of light absorption. However, the group III-V compound semiconductor film with a small energy gap (for example, at least 500 angstroms or less, and a typical value of 300 angstroms or less) can allow the carrier concentration to be increased. In particular, for the aforementioned p-type ohmic contact layer 110, in order to prevent the problem of light absorption, a material with a high energy gap, such as GaP, must be selected for the energy gap. As a result, it is very difficult to increase the concentration of p-type carriers. Conversely, gallium arsenide with a small energy gap But it can solve the problem of high-concentration carrier doping. In the present invention, the carrier concentration in the 113g of the gallium arsenide film can be increased to 1×10¹⁹/cm³above. This requires a concentration of 5×10 for a typical good ohmic contact¹⁸/cm³. Of course there is more than enough. The high-concentration gallium arsenide thin film layer 113g can form a good ohmic contact with the transparent conductive oxide layer 114. Therefore, the current injected into the transparent conductive oxide layer from the conductive heat dissipation substrate 125 through the reflective metal layer 116 can first be evenly distributed on the gallium arsenide thin film layer 113g, and then incident on the light emitting diode epitaxial layer 1000 to the n electrode 130 to be formed A current path. In spite of this, in order to prevent the shortcomings of gallium arsenide from absorbing light from overriding its advantages of evenly spreading current, the thickness has to be limited as described above.

For the gallium arsenide layer 113g at or below the above thickness, the light transmittance will increase as its thickness becomes thinner. It is worthwhile to sacrifice a part of the light transmittance to make the injected current perpendicular to the light-emitting diode epitaxial layer 1000 spread more uniformly. In order to spread the current uniformly between the transparent conductive oxide layer 114 and the light emitting diode epitaxial layer 1000 through the metal layer with good ohmic contact, please refer to the third embodiment shown in FIG. 8. A transparent thin ohmic contact metal layer (TCL layer) 113t is first deposited on the light emitting diode epitaxial layer 1000 including the temporary substrate 100, and then the transparent conductive oxide layer is formed on the TCL layer 113t . The subsequent steps are the same as described above. The thin ohmic contact metal layer TCL layer 113t, such as a 100 angstrom thick gold/nickel layer, or gold/beryllium, or gold/zinc composite layer, can form very good ohmic contact with the transparent conductive oxide layer 114, so The current injected into the light-emitting diode epitaxial layer 1000 can also be evenly distributed. The thin TCL layer 113t is light-transmissive at the thickness, so it will not sacrifice too much from the light-emitting diode epitaxial layer. The problem of absorption of light exiting and toward the reflective metal layer (including secondary absorption).

Please refer to FIG. 9 for the fourth embodiment of the present invention. First, a transparent conductive oxide layer 114 is fully formed on one of the light-emitting diode epitaxial layers including a temporary substrate, and then a plurality of ohmic contact channels 115 are defined on the transparent conductive layer by lithography patterns and dry etching steps. In the type oxide layer 114, as shown in the figure, the ohmic contact channel penetrates the upper and lower sides of the transparent conductive type oxide layer 114, and then the ohmic contact metal layer is backfilled. The ohmic contact metal layer can fill or incompletely fill the ohmic contact channel 115, and finally a highly reflective reflective metal layer 116 is formed on the transparent conductive oxide layer 114, and at the same time, the previously incompletely filled The ohmic contact channel 115 is filled. As mentioned above, the metal in the ohmic contact channels 115 is used to make the current from the conductive heat-dissipating substrate spread evenly on the light-emitting diode epitaxial layer through these channels 115. In a preferred embodiment, the area ratio occupied by the ohmic contact channel 115 may be less than 10% of the interface between the transparent conductive oxide layer 114 and the epitaxial diode layer 1000.

The present invention has the following advantages: (1) It provides a vertical current injection type light-emitting diode structure, and only a single gold wire is needed, so the packaging process of the light-emitting diode can be simplified and the production cost can be reduced. . (2) The size of the light-emitting diode can be greatly reduced, so that the number of light-emitting diode crystal grains produced per chip increases. (3) It has good heat dissipation, so LED has good reliability performance and can be operated under high current density. (4) It is easy to mass produce, with high yield and low cost. (5) The reflective metal layer can withstand higher temperatures without deteriorating the quality of the reflective metal layer, so it can provide greater flexibility in chip manufacturing.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the patent application of the present invention. All other equivalent changes or modifications made without departing from the spirit of the present invention should be included in the following Within the scope of the patent application.

<p>1,100. . . Gallium Arsenide Substrate</p><p>2. . . Dispersed Bragg reflector</p><p>2a. . . GaAs buffer layer</p><p>3. 45, 104. . . n-type cladding</p><p>5. 41, 106. . . Active layer</p><p>7, 43, 108. . . p-type cladding</p><p>9. . . p-type high energy gap current dispersion layer</p><p>10. . . Blocking area</p><p>11. . . p-type gallium phosphide) window layer</p><p>13, 52. . . Transparent layer TS</p><p>12, 40, 1000. . . Light emitting epitaxial layer</p><p>19, 47a, 130. . . n-type ohmic contact metal electrode</p><p>27, 120. . . Silicon substrate</p><p>102. . . Etch stop layer</p><p>112. . . p-type ohmic metal contact pattern layer</p><p>124. . . Adhesive layer</p><p>47, 116. . . Highly reflective metal layer</p><p>113t. . . Transparent ohmic contact metal layer</p><p>114. . . Transparent conductive oxide layer</p><p>110. . . P-type ohmic contact epitaxial layer</p><p>126. . . Diffusion barrier</p><p>54, 115. . . Ohmic contact channel</p><p>53. . . Dielectric layer</p><p>113g. . . Thin gallium arsenide layer</p><p>49. . . Ohmic contact point</p>

The preferred embodiment of the present invention will be described in more detail in the following description with the following figures: Figure 1 is a schematic cross-sectional view of a light-emitting diode structure manufactured according to the prior art. Figure 2 is a schematic cross-sectional view of a light-emitting diode with a dispersed Bragg reflective layer according to the prior art. The third figure shows that the light-emitting diode manufactured according to the conventional technology has a transparent material formed according to the adhesive technology as the substrate. Figure 4 shows a light-emitting diode layer fabricated according to the prior art. The doped reflective metal layer is in ohmic contact with n-type GaP and p-type GaP by means of laser heating. Figure 5 shows a light-emitting diode layer fabricated according to the conventional technology, using the dielectric layer and several ohmic contact channels formed therein to allow the reflective metal layer current to pass through to the n-electrode, while also preventing the reflective metal layer from emitting light The reaction of the diode epitaxial layer. Figures 6A to 6C illustrate the structure of the light-emitting diode epitaxial layer fabricated by the first embodiment of the method of the present invention, the substrate structure, and the structure after the two are bonded, with an inert transparent conductor layer on the reflective metal layer and the epitaxy Schematic diagram of the cross-section between the crystal layer structures. Fig. 7 shows the second embodiment of the method according to the present invention. A thin gallium arsenide epitaxial layer doped with highly conductive impurities is used as the ohmic contact medium between the transparent conductive oxide layer and the light-emitting diode epitaxial layer. Schematic diagram. Figure 8 shows the third embodiment of the method according to the present invention, using the TCL layer as the ohmic contact medium between the transparent conductive oxide layer and the light-emitting diode epitaxial layer Schematic diagram. Fig. 9 is a schematic diagram of the ohmic contact channel formed in the transparent conductive oxide layer according to the fourth embodiment of the method of the present invention, and the medium between the transparent conductive oxide layer and the light emitting diode epitaxial layer.