JP2007059830A - High-intensity light-emitting diode having reflection layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-intensity light-emitting diode having a reflection layer. <P>SOLUTION: The high-intensity light-emitting diode includes a luminous structure, a non-alloy ohmic contact layer, a metal layer, and a substrate in this order. As a reflector, the metal layer is formed by a pure metal or metal nitride to attain an improved reflection factor. The non-alloy ohmic contact layer is interposed between the metal layer and the luminous structure, thus attaining required ohmic contact. For preventing the fusion between the metal layer and the non-alloy ohmic contact layer and for maintaining flatness in the reflection surface of the metal layer, an optical transmission layer is interposed between the metal layer and the non-alloy ohmic contact layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting diode, and more particularly to a light emitting diode including a reflective layer that prevents light absorption by the diode surface.

  FIG. 1 is a cross-sectional view of a typical structure of a known light emitting diode (LED). As shown, the LED 100 includes a semiconductor substrate 103, a light emitting structure 102 positioned on the substrate 103, two ohmic contact electrodes 109 formed on the opposite side of the substrate 103 and on the light emitting structure 102, and 101.

  The light emitting structure 102 is often formed of multiple layers of aluminum bearing III-V compound semiconductors such as AlGaAs, yellow green, yellow, amber for infrared and red light generation, and AlGaInP for red light. ing. The substrate 103 is typically made of gallium arsenide (GaAs), which has a lattice constant that matches the lattice constant of the light emitting structure 102. Light generated by the light emitting structure 102 is emitted in all directions (ie, isotropic), but GaAs has an energy gap that is smaller than the energy gap of visible light and is therefore emitted by the light emitting structure 102. An important part of the light is absorbed by the GaAs substrate 103, which affects the external quantum effect of the LED 100 and thus the brightness of the LED 100.

  FIG. 2 is a cross-sectional view of a typical structure of another known light emitting diode. As shown, the LED 100 'requires etching a portion of the light emitting structure 102' to form an electrode 101 'and an electrode 109' on the same side of the LED 100 '. Further, in the LED 100 of FIG. 1, the substrate 103 must be conductive in order to conduct the injected current between the electrodes 101 and 109, whereas the LED 100 ′ of FIG. It may be non-conductive. Like LED 100, LED 100 'still has the same substrate light absorption problem. The LED 100 of FIG. 1 has a vertical electrode arrangement, while the LED 100 ′ of FIG. 2 has a planar electrode arrangement.

  Various means are provided to overcome the problem of light absorption by the substrate. For example, Patent Document 1 and Patent Document 2 show a light-emitting diode structure similar to that shown in FIG. 1 except that the light-emitting structure is formed on a substrate with a bottom distributed Bragg reflector (DBR) and an upper distributed Bragg. It is sandwiched between reflectors. With this DBR structure, light emitted from the light emitting structure toward the substrate is reflected, and absorption by the substrate is prevented. However, DBR can only provide a high reflectivity for normal incident light, and the reflectivity decreases as the incident angle of light increases. The external quantum effect and brightness improvement of the light-emitting diode is thus limited.

  U.S. Pat. No. 6,057,836 shows another two means, which use a wafer bonding process. In one means, an LED epitaxial structure is first grown on a GaAs substrate. The LED epitaxial structure is then wafer bonded to the transparent substrate. In another approach, similarly, an LED epitaxial structure is first grown on a GaAs substrate. The LED epitaxial structure is then wafer bonded to the mirror. Either means improves the LED external quantum effect by removing the GaAs substrate that absorbs light, the former means allows light to pass through the transparent substrate, and the latter means reflects it by a mirror. However, a problem with the means of using a transparent substrate is that the wafer bonding process requires high annealing temperatures over the stretch period, which can lead to doping profile reconstruction and LED performance degradation. The problem with the means of using a mirror is that the reflective surface of the mirror is directly involved in the bonding interface during the wafer bonding process and can cause roughness or poor reactivity or contamination of the reflective surface.

  According to the technique described in Non-Patent Document 1, a silicon substrate with an Au / AuBe reflector is bonded to the LED epitaxial structure before removing the GaAs substrate. Usually, Au / AuBe is used to form ohmic contacts with p-type materials in AlGaInP LEDs. In the technique described in Non-Patent Document 1, Au / AuBe is used as a bonding layer and a metal mirror in a wafer bonding LED epitaxial structure. However, the reflectivity of the alloy material AuBe is low, so that the improvement of the brightness of the LED is limited. The alloy process usually requires a high annealing temperature, which reduces the surface flatness of the reflector and lowers the reflectivity.

  Patent Document 4 describes a light emitting diode using a reflective metal layer. The structure interposes a transparent conductive oxide layer, such as ITO, to prevent the reflective metal layer from reacting with the light emitting structure during the wafer bonding process. In order to improve the ohmic contact between the ITO layer and the light emitting structure, the described structure requires that an ohmic contact grid pattern or channel be formed in the ITO layer or an alloy mesh be formed between the ITO layer and the light emitting structure. Presenting. This structure is complicated in manufacturing process and therefore expensive to manufacture. Alloy mesh requires a high temperature alloy process, and etching the alloy to form a mesh is very difficult to control. In addition, very careful attention must be paid to the thickness of the alloy. If the alloy is too thin, the ohmic contact between the alloy and the light emitting structure will be poor, and if the alloy is too thick, the wafer bonding process cannot achieve a strong bond.

US Pat. No. 4,570,172 US Pat. No. 5,237,581 US Pat. No. 5,376,580 US Pat. No. 6,797,987 “AlGaInP light-emitting diodes with mirror substratified by wafer bonding” Horn et al. Physics Letters, November 15, 1999, Volume 75, Issue 20, pp. 3054-3056

  Accordingly, it is a primary object of the present invention to provide a high brightness LED structure which improves the light absorption problem due to the substrate in the known art.

  According to the present invention, the LED structure includes a light emitting structure and a non-alloy ohmic contact layer, a first metal layer, and a substrate disposed on one side of the light emitting structure in the following order. After the LED structure is formed, a chip process for packaging the LED structure into an LED chip is performed to perform electrode formation and other appropriate operations.

  The substrate may be either conductive or non-conductive. If a non-conductive substrate is used, the electrodes formed in the subsequent chip process need to be arranged in a planar form. If a conductive substrate is used, the electrodes can be arranged in a vertical or planar configuration. In a planar electrode arrangement, the LED structure can optionally have an insulating layer disposed between the substrate and the bottom metal layer for superior insulating performance.

  The most important feature of the present invention is the bonding effect provided by the non-alloy ohmic contact layer and the first metal layer to the substrate light absorption problem. The first metal layer functions as a reflector, and pure metal or metal nitride is used in place of the traditional alloy reflector, thereby avoiding the low reflectivity and high annealing temperature of the alloy metal, non-alloy ohmic The contact layer is interposed between the light emitting structure and the first metal layer, thereby achieving the required low resistance conductivity. The material used for the non-alloy ohmic contact layer is selectively transparent or absorbs light. For light absorbing non-alloy ohmic contact layers, the number of recesses is selectively determined and formed along the bottom surface, thereby reducing light absorption and improving injected current distribution. For transparent non-alloy ohmic contact layers, recesses are formed to improve the injected current distribution.

  Further, in order to prevent fusion of the first metal layer with the non-alloy ohmic contact layer and the light emitting structure, and to maintain the flatness of the reflective surface of the first metal layer, a selectively transparent and conductive first dielectric layer is provided. It can be inserted between one metal layer and a non-alloy ohmic contact layer. Furthermore, at least one additional metal layer can be inserted between the first metal layer and the substrate in order to achieve good bonding between the substrate and the first metal layer. Similarly, a second dielectric layer may be inserted between the first metal layer and the additional metal layer to prevent fusion of the additional metal layer with the first metal layer and a decrease in reflectivity of the first metal layer. .

  The foregoing and other objects, aspects, features and advantages of the present invention will be described in further detail with reference to the drawings in the following description of embodiments.

The invention of claim 1 is a light emitting diode structure comprising a plurality of layers arranged in order from bottom to top,
A substrate,
A first metal layer formed on the substrate with pure metal or metal nitride;
An unalloyed ohmic contact layer formed on the first metal layer;
A light emitting structure formed on the non-alloy ohmic contact layer to generate light by energization of the light emitting diode structure;
The light emitting diode structure is characterized by including the above.
The invention according to claim 2 is the light emitting diode structure according to claim 1, wherein the first metal layer is made of Au, Al, Ag, titanium nitride (TiNx), zirconium nitride (ZrNx), It has a light emitting diode structure.
According to a third aspect of the present invention, the light-emitting diode structure according to the first aspect further includes a first dielectric layer having optical transparency and being located between the first metal layer and the non-alloy ohmic contact layer. The light emitting diode structure is characterized by this.
According to a fourth aspect of the present invention, there is provided the light emitting diode structure according to the third aspect, wherein the first dielectric layer is a transparent conductive oxide.
The invention according to claim 5 is the light emitting diode structure according to claim 4, wherein the first dielectric layer is indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), antimony-doped SnO, fluorine Doped SnO, phosphorus doped SnO, zinc oxide (ZnO), aluminum doped ZnO, indium oxide (InO), cadmium oxide (CdO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO), copper calcium The light emitting diode structure is characterized by being formed of either an oxide (CuCaO) or strontium copper oxide (SrCuO).
According to a sixth aspect of the present invention, there is provided the light emitting diode structure according to the first aspect, further comprising a second metal layer positioned between the first metal layer and the substrate.
A seventh aspect of the present invention is the light emitting diode structure according to the sixth aspect, wherein the second metal layer is formed of one kind of pure metal or alloy.
The invention of claim 8 is the light emitting diode structure according to claim 6, further comprising a second dielectric layer positioned between the first metal layer and the second metal layer. .
According to a ninth aspect of the present invention, in the light emitting diode structure according to the eighth aspect, the second dielectric layer is formed of any one of the following three materials: a transparent conductive oxide, a metal nitride, and an insulating material. The light emitting diode structure is characterized by the following.
The invention according to claim 10 is the light emitting diode structure according to claim 9, wherein the second dielectric layer comprises indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), antimony-doped SnO, Fluorine-doped SnO, phosphorus-doped SnO, zinc oxide (ZnO), aluminum-doped ZnO, indium oxide (InO), cadmium oxide (CdO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO), copper A light-emitting diode formed of calcium oxide (CuCaO) and strontium copper oxide (SrCuO), TiNx, ZrNx, or an insulating material, silicon nitride (SiNx), or silicon oxide (SiOx) It has a structure.
The invention of claim 11 is the light emitting diode structure according to claim 6, further comprising a third metal layer located between the second metal layer and the substrate.
The invention of claim 12 is the light emitting diode structure according to claim 11, wherein the third metal layer is made of pure gold or an alloy.
A thirteenth aspect of the present invention is the light emitting diode structure according to the first aspect, wherein the non-alloy ohmic contact layer is a doped semiconductor layer.
The invention according to claim 14 is the light emitting diode structure according to claim 13, wherein the non-alloy ohmic contact layer is made of carbon-doped AlAs, carbon-doped GaP, carbon-doped AlP, carbon-doped AlGaAs, carbon-doped InAlAs, carbon-doped InGaP, carbon-doped. InAlP, carbon doped AlGaP, carbon doped GaAsP, carbon doped AlAsP, carbon doped AlGaInP, carbon doped AlGaInAs, carbon doped InGaAsP, carbon doped AlGaAsP, carbon doped AlInAsP, carbon doped InGaAlAsP, magnesium doped AlAs, magnesium doped GaP, magnesium doped AlP, Magnesium doped AlGaAs, magnesium doped InAlAs, magnesium doped InGaP, magnesium doped InA P, magnesium doped AlGaP, magnesium doped GaAsP, magnesium doped AlAsP, magnesium doped AlGaInP, magnesium doped AlGaInAs, magnesium doped InGaAsP, magnesium doped AlGaAsP, magnesium doped AlInAsP, magnesium doped InGaAlAsP, zinc doped AlAs, zinc doped GaP, zinc doped AlP, Zinc doped AlGaAs, Zinc doped InAlAs, Zinc doped InGaP, Zinc doped InAlP, Zinc doped AlGaP, Zinc doped GaAsP, Zinc doped AlAsP, Zinc doped AlGaInP, Zinc doped AlGaInAs, Zinc doped InGaAsP, Zinc doped AlGaAsP, Zinc doped AlInAsP, Zinc doped In aAlAsP, carbon doped InP, carbon doped InAs, carbon doped GaAs, carbon doped InAsP, magnesium doped InP, magnesium doped InAs, magnesium doped GaAs, magnesium doped InAsP, zinc doped InAs, zinc doped GaAs, zinc doped InAsP Thus, a light emitting diode structure is provided.
The invention according to claim 15 is the light-emitting diode structure according to claim 1, wherein the non-alloy ohmic contact layer comprises a plurality of recesses along the interface between the non-alloy ohmic contact layer and the first metal layer. The light emitting diode structure is used.
According to a sixteenth aspect of the present invention, there is provided the light emitting diode structure according to the first aspect, wherein the substrate is a conductive substrate.
The invention according to claim 17 is the light emitting diode structure according to claim 16, wherein the substrate is doped Ge, doped Si, doped GaAs, doped GaP, doped InP, doped InAs, doped GaN, doped AlGaAs, doped SiC, doped The light emitting diode structure is formed of any one of GaAsP, Mo, Cu, and Al.
The invention according to claim 18 is the light emitting diode structure according to claim 16, further comprising an insulating layer provided immediately above the substrate for the planar arrangement of the electrodes of the light emitting diode structure. Yes.
The nineteenth aspect of the present invention is the light emitting diode structure according to the eighteenth aspect, wherein the insulating layer is formed of either silicon nitride (SiNx) or silicon oxide (SiOx).
A twentieth aspect of the present invention is the light emitting diode structure according to the first aspect, wherein the substrate is a non-conductive substrate.
The invention according to claim 21 is the light emitting diode structure according to claim 20, wherein the substrate is made of Ge, Si, GaAs, GaP, InP, InAs, GaN, AlN, AlGaAs, SiC, GaAsP, sapphire, glass, quartz, and ceramic. The light-emitting diode structure is characterized by being formed of either one.

  The present invention provides a high brightness light emitting diode with a reflective layer, which includes a light emitting structure, a non-alloy ohmic contact layer, a metal layer, and a substrate arranged in the following order. As a reflector, the metal layer is made of pure metal or metal nitride to achieve excellent reflectivity. The non-alloy ohmic contact layer is interposed between the metal layer and the light emitting structure, thereby achieving the required ohmic contact. In order to prevent the fusion of the metal layer with the non-alloy ohmic contact layer and to maintain the flatness of the reflective surface of the metal layer, an optical transmission layer is interposed between the metal layer and the non-alloy ohmic contact layer.

  The following description relates only to the embodiments of the present invention, and is not intended to limit the application, form, or scope of the present invention. Any modification or alteration in detail that can be made based on the drawings and the following description is not limited to the present invention. Shall belong to the claims.

  FIG. 3 is a sectional view of the first embodiment of the present invention. As shown, the LED structure includes a light emitting structure 202. The light emitting structure 202 includes an active pn junction layer that emits light when energized. The light emitting structure 202 typically, but not necessarily, includes a plurality of III-V compound semiconductor layers. The precise details of the light emitting structure 202 are not strictly pursued in the present invention. For easy reference, all directions facing the light emitting structure 202 and positions close to the light emitting structure 202 are referred to as an upper direction or an upper position, and the opposite side is referred to as a bottom direction or a bottom position in FIGS. Is done.

  The light emitting structure 202 is on the first metal layer 205. The first metal layer 205 functions as a reflecting mirror. Therefore, light emitted from the light emitting structure 202 toward the first metal layer 205 is reflected and returns to the light emitting structure 202. The first metal layer 205 is made of pure metal or metal nitride, for example, Au, Al, Ag, titanium nitride (TiNx), or zirconium nitride (ZrNx). Pure metals or metal nitrides are employed in place of traditional alloy reflectors, thereby achieving excellent reflectivity and avoiding high annealing temperatures. A non-alloy ohmic contact layer 204 is inserted between the light emitting structure 202 and the first metal layer 205 to achieve the required low resistance conductivity.

The non-alloy ohmic contact layer 204 is selectively, but not limited to, transparent or light-absorbing, p-type or n-type doped, and the semiconductor layer typically has at least 1E19 / cm ³ . Typical examples of the non-alloy ohmic contact layer 204 include, but are not limited to, carbon doped AlAs, carbon doped GaP, carbon doped AlP, carbon doped AlGaAs, carbon doped InAlAs, carbon doped InGaP, carbon doped InAlP, carbon doped AlGaP. , Carbon doped GaAsP, carbon doped AlAsP, carbon doped AlGaInP, carbon doped AlGaInAs, carbon doped InGaAsP, carbon doped AlGaAsP, carbon doped AlInAsP, carbon doped InGaAlAsP, magnesium doped AlAs, magnesium doped GaP, magnesium doped AlP, magnesium doped AlGaAs, magnesium Doped InAlAs, magnesium doped InGaP, magnesium doped InAlP, magnesium doped lGaP, magnesium doped GaAsP, magnesium doped AlAsP, magnesium doped AlGaInP, magnesium doped AlGaInAs, magnesium doped InGaAsP, magnesium doped AlGaAsP, magnesium doped AlInAsP, magnesium doped InGaAlAsP, zinc doped AlAs, zinc doped GaP, zinc doped AlP, zinc doped AlGaAs, Zinc doped InAlAs, zinc doped InGaP, zinc doped InAlP, zinc doped AlGaP, zinc doped GaAsP, zinc doped AlAsP, zinc doped AlGaInP, zinc doped AlGaInAs, zinc doped InGaAsP, zinc doped AlGaAsP, zinc doped AlInAsP, zinc doped InGaAlAsP, carbon doped Including InP, carbon-doped InAs, carbon-doped GaAs, carbon-doped InAsP, magnesium-doped InP, magnesium doped InAs, magnesium-doped GaAs, magnesium doped InAsP, zinc-doped InAs, zinc-doped GaAs, a zinc-doped InAsP. The above-described doped compound semiconductor can be transparent or light-absorbing depending on the component composition.

  In another embodiment, the non-alloy ohmic contact layer 204 is selectively etched after its formation to form a plurality of recesses 2041. This is as shown in FIG. The advantage of having the recesses 2041 is that they help control the injected current distribution. Another advantage of the recesses 2041 is that they reduce light absorption when the non-alloy ohmic contact layer 204 is selectively formed of a light absorbing material. The etching depth is usually such that a part of the light emitting structure 202 is exposed.

  In another embodiment, a selectively transparent and conductive first dielectric layer 2051 is inserted between the first metal layer 205 and the non-alloy ohmic contact layer 204, as shown in FIG. It is to prevent fusion between the first metal layer 205 and the non-alloy ohmic contact layer 204, and the light emitting structure 202 can improve reflectivity and flatness of the reflective surface of the first metal layer 205 when they have a recess 2041. Can be maintained. The first dielectric layer 2051 is typically formed of a transparent electrically conductive oxide (TCO). Typical examples include, but are not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), antimony doped SnO, fluorine doped SnO, phosphorus doped SnO. Zinc oxide (ZnO), aluminum doped ZnO, indium oxide (InO), cadmium oxide (CdO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO), copper calcium oxide (CuCaO), And strontium copper oxide (SrCuO).

  In other embodiments, a second metal layer 206 may be disposed between the substrate 207 and the first metal layer 205, as shown in FIG. The second metal layer 206 is formed of a pure metal or an alloy, and is provided to enhance the bonding force to the substrate 207 in the wafer bonding process for forming the LED structure of the present invention. The manufacturing method will be described later. Similarly, in order to prevent the fusion of the second metal layer 206 with the first metal layer 205 and to maintain the reflectivity of the first metal layer 205, the second dielectric layer 2061 is formed from the first metal layer 205 and the second metal layer 205. It can be placed between the layers 206, as shown in FIG.

  It is important to note that: The first metal layer 205 acts as a reflector, and the second dielectric layer 2061 of selective nature is not important. Furthermore, if the LED structure of FIG. 7 includes electrodes arranged in a vertical configuration, the second dielectric layer 2061 is conductive, thereby forming a conductive path between the electrodes. If the LED structure in FIG. 7 includes electrodes arranged in a planar form, the presence or absence of conductivity of the second dielectric layer 2061 does not affect the arrangement of the planar electrodes. Further details will be described later.

  It should also be noted that an additional pair of dielectric layers and metal layers may be provided between the second metal layer 206 and the substrate 207. Similarly, these additional dielectric layers are not required to have optical transparency and electrical conductivity, and these additional metal layers can be formed of pure metals or alloys. The second dielectric layer 2061 and these additional dielectric layers include, as described above, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), antimony doped SnO, fluorine doped SnO, Phosphorus-doped SnO, zinc oxide (ZnO), aluminum-doped ZnO, indium oxide (InO), cadmium oxide (CdO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO), copper calcium oxide ( CuCaO), and strontium copper oxide (SrCuO), and metal nitrides such as TiNx, ZrNx (which do not have optical transparency), or insulating materials such as silicon nitride (SiNx), silicon oxide (SiOx) Can be formed. FIG. 8 shows another embodiment of the present invention. As shown, a third metal layer 208 made of pure metal or alloy is formed on the substrate 207, the purpose of which is to enhance the expression of the wafer bonding process. Further details are provided in the manufacturing process described below.

  Since the first metal layer 205 reflects most of the light toward the substrate, the engineering properties of the substrate 207 are not important. The substrate 207 is a semiconductor substrate, a metal substrate, or other suitable substrate. The substrate 207 may or may not be electrically conductive. Typical materials for the conductive substrate include, but are not limited to, doped Ge, doped Si, doped GaAs, doped GaP, doped InP, doped InAs, doped GaN, doped AlGaAs, doped SiC, Includes doped GaAsP, Mo, Cu, and Al. Typical non-conductive substrate 207 ′ materials include, but are not limited to, Ge, Si, GaAs, GaP, InP, InAs, GaN, AlN, AlGaAs, SiC, GaAsP, sapphire, glass, quartz And ceramic.

  The substrate 207 is conductive, and the electrodes 201 and 209 are arranged in a vertical configuration in the subsequent chip process, as shown in FIG. If the substrate 207 is non-conductive, the electrodes 201 and 209 must be arranged in a planar form. As shown in FIG. 10, a part of the LED structure in FIG. 8 is etched to a predetermined depth to expose a region of one metal layer located between the non-alloy ohmic contact layer 204 and the substrate 207. In this embodiment, the region of the first metal layer 205 is exposed by etching. Electrodes 201 and 209 are then formed on the light emitting structure 202 and on the exposed region of the first metal layer 205, respectively. It should be noted that as long as there are multiple metal layers and there is a current path between the electrodes 201 and 209, there is no limit to the etch depth for the LED structure. For example, as shown in FIG. 11, the LED structure is etched until the second metal layer 206 is exposed. As described above, the presence / absence of electrical conductivity of the second dielectric layer 2061 affects one arrangement of the planar electrodes. Therefore, in order for the planar electrodes 201 and 209 in FIG. 11 to act, the second dielectric layer 2061 must be conductive. On the other hand, the second dielectric layer 2061 in FIG. 10 can be made non-conductive because it is not on the current path between the electrodes 201 and 209.

If the electrode 207 is conductive, the electrodes 201 and 209 can be arranged in a planar form as shown in FIG. Similarly, the LED structure is etched so that the second metal layer 206 is exposed. Electrodes 201 and 209 are then formed on the light emitting structure 202 and on the exposed second metal layer 206. Since the substrate 207 is conductive, the insulating layer 2071 is directly disposed on the substrate 207 and positioned below the metal layer. The insulating layer 2071 is formed of any of the following materials. That is, SiNx and SiOx ₋ . Note that the insulating layer 2071 is not necessarily provided if at least one of the second dielectric layer 2061 and the additional dielectric is non-conductive. However, the insulating layer 2071 can still be implemented because the dielectric layer usually cannot provide the necessary insulation. For good insulation performance, the insulating layer 2071 is similarly implemented in FIG. 10 (having non-conductive 207).

  12-17 illustrate the formation process of FIG. As shown in FIG. 12, a temporary growth substrate 203 is first provided, and then a plurality of half body layers forming the light emitting structure 202 are grown on one side of the temporary growth substrate 203. The main consideration with respect to the substrate 203 is to achieve good luminous efficiency by the light emitting structure 202. For example, the substrate 203 is formed of a material such as GaAs, and the lattice of GaAs matches the light emitting structure 202.

  Then, as shown in FIG. 13, a non-alloyed ohmic contact layer 204 is subsequently disposed on the light emitting structure 202 using an epitaxial growth tool, vacuum deposition, deposition, sputtering, or plating techniques. The formation of the non-alloy ohmic contact layer 204 can be performed immediately after the first growth process of the light emitting structure 202 in the same reactor. Alternatively, an epitaxial structure including the light emitting structure 202 and the substrate 203 is manufactured and stored separately. In order to improve the injection current distribution and / or reduce the light absorption by the non-alloy ohmic contact layer 204, a plurality of recesses 2041 are formed on the surface of the non-alloy ohmic contact layer 204 by etching.

  As shown in FIG. 14, the first dielectric layer 2051, the first metal layer 205, the second dielectric layer 2061, and the second metal layer 206 are arranged in this order by vacuum deposition, deposition, sputtering, or plating technique. The non-alloy ohmic contact layer 204 is covered with

  Thereafter, a conductive substrate 207 is provided, and a third metal layer 208 is formed on one side of the permanent substrate 207 by vacuum deposition, deposition, sputtering or plating techniques, as shown in FIG. It is.

  A wafer bonding process is then performed to join the structures of FIGS. 14 and 15 and a second metal layer 206 is interposed with the third metal layer 208 as in FIG. It should be noted that the second metal layer 206 and the third metal layer 208 act as bonding materials during the wafer bonding process, thereby lowering the annealing temperature of the wafer bonding process and shortening the operation period. Further, the third metal layer 208 provides the necessary ohmic contact to the substrate 207.

  Compared to wafer bonding of the known reflector to the light emitting structure, the present invention directly coats the light emitting structure 202 with the first metal layer 205 (i.e., reflector) prior to the wafer bonding process. The reflective surface of the reflector does not directly participate in the bonding interface during the wafer bonding process. Therefore, the roughness or reactivity of the reflecting surface and contamination are prevented. The first metal layer 205 of the present invention can thus provide a better reflectivity than that formed by the prior art.

  The temporary growth substrate 203 is then removed. The removal of the temporary growth substrate 203 is performed after the light emitting structure 202 is bonded to the permanent substrate 207, thereby avoiding problems due to the light emitting structure 202 being too thin. Next, a traditional chip process is performed to package the LED structure in the chip. This involves placing two metal films on the top and bottom electrodes 209 and 201, respectively, as shown in FIG.

  The LED structure shown in FIG. 10 or FIG. 11 can be formed using essentially the same process. The difference is that, first, in FIG. 15, the electrical properties of the permanent substrate 207 must be properly determined. Next, prior to electrode formation, the LED structure is etched to a predetermined depth from the light emitting structure 202 to one of the metal layers. Third, the electrodes 201 and 209 are formed on the light emitting structure 202 and on the exposed metal layer, respectively.

  Although the present invention is illustrated in the preferred embodiments above, the present invention is not limited to the details of these embodiments. Various changes and modifications can be made based on the foregoing description. Therefore, the scope of the present invention shall conform to the description of the scope of claims.

1 is a cross-sectional view of an exemplary structure of a known light emitting diode (LED). FIG. 3 is a cross-sectional view of a typical structure of another known light emitting diode. It is sectional drawing of the light emitting diode of 1st Example of this invention. It is sectional drawing of the light emitting diode of 2nd Example of this invention. It is sectional drawing of the light emitting diode of 3rd Example of this invention. It is sectional drawing of the light emitting diode of 4th Example of this invention. It is sectional drawing of the light emitting diode of 5th Example of this invention. It is sectional drawing of the light emitting diode of 6th Example of this invention. It is sectional drawing which shows the electrode formation process of the light emitting diode of the Example of this invention. It is sectional drawing which shows the electrode formation process of the light emitting diode of the Example of this invention. It is sectional drawing which shows the electrode formation process of the light emitting diode of the Example of this invention. It is sectional drawing which shows the formation process of the structure of FIG. 3 of this invention. It is sectional drawing which shows the formation process of the structure of FIG. 3 of this invention. It is sectional drawing which shows the formation process of the structure of FIG. 3 of this invention. It is sectional drawing which shows the formation process of the structure of FIG. 3 of this invention. It is sectional drawing which shows the formation process of the structure of FIG. 3 of this invention. It is sectional drawing which shows the formation process of the structure of FIG. 3 of this invention.

Explanation of symbols

100 LED
102 Light Emitting Structure 103 Substrate 101, 109 Electrode 100 ′ LED
101 ', 109' Electrode 102 'Light emitting structure 103' Substrate 202 Light emitting structure 205 First metal layer 204 Non-alloy ohmic contact layer 2041 Recess 2051 First dielectric layer 206 Second metal layer 207 Substrate 2061 Second dielectric layer 208 Third metal Layer 2071 Insulating layer 203 Temporary growth substrate

Claims (21)

A light emitting diode structure comprising a plurality of layers arranged in order from bottom to top,
A substrate,
A first metal layer formed on the substrate with pure metal or metal nitride;
An unalloyed ohmic contact layer formed on the first metal layer;
A light emitting structure formed on the non-alloy ohmic contact layer to generate light by energization of the light emitting diode structure;
A light-emitting diode structure comprising:   2. The light emitting diode structure according to claim 1, wherein the first metal layer is made of Au, Al, Ag, titanium nitride (TiNx), or zirconium nitride (ZrNx).   2. The light emitting diode structure of claim 1, further comprising a first dielectric layer that is optically transmissive and electrically conductive and located between the first metal layer and the non-alloy ohmic contact layer. Diode structure.   4. The light emitting diode structure according to claim 3, wherein the first dielectric layer is a transparent conductive oxide.   5. The light emitting diode structure of claim 4, wherein the first dielectric layer is indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), antimony doped SnO, fluorine doped SnO, phosphorus doped SnO, Zinc oxide (ZnO), aluminum-doped ZnO, indium oxide (InO), cadmium oxide (CdO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO), copper calcium oxide (CuCaO), and A light emitting diode structure formed of any one of strontium copper oxide (SrCuO).   2. The light emitting diode structure according to claim 1, further comprising a second metal layer positioned between the first metal layer and the substrate.   7. The light emitting diode structure according to claim 6, wherein the second metal layer is formed of one kind of pure metal or alloy.   7. The light emitting diode structure according to claim 6, further comprising a second dielectric layer located between the first metal layer and the second metal layer.   9. The light emitting diode structure according to claim 8, wherein the second dielectric layer is formed of any one of the following three types of materials: a transparent conductive oxide, a metal nitride, and an insulating material. Construction.   10. The light emitting diode structure according to claim 9, wherein the second dielectric layer comprises indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), antimony-doped SnO, fluorine-doped SnO, phosphorus-doped SnO. Zinc oxide (ZnO), aluminum doped ZnO, indium oxide (InO), cadmium oxide (CdO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO), copper calcium oxide (CuCaO), And a strontium copper oxide (SrCuO), TiNx, ZrNx, or an insulating material, silicon nitride (SiNx), silicon oxide (SiOx).   7. The light emitting diode structure according to claim 6, further comprising a third metal layer located between the second metal layer and the substrate.   12. The light emitting diode structure according to claim 11, wherein the third metal layer is formed of pure gold or an alloy.   2. The light emitting diode structure according to claim 1, wherein the non-alloy ohmic contact layer is a doped semiconductor layer.   14. The light emitting diode structure according to claim 13, wherein the non-alloy ohmic contact layer comprises carbon doped AlAs, carbon doped GaP, carbon doped AlP, carbon doped AlGaAs, carbon doped InAlAs, carbon doped InGaP, carbon doped InAlP, carbon doped AlGaP, carbon. Doped GaAsP, carbon doped AlAsP, carbon doped AlGaInP, carbon doped AlGaInAs, carbon doped InGaAsP, carbon doped AlGaAsP, carbon doped AlInAsP, carbon doped InGaAlAsP, magnesium doped AlAs, magnesium doped GaP, magnesium doped AlP, magnesium doped AlGaAs, magnesium doped InAlAs , Magnesium doped InGaP, magnesium doped InAlP, magnesium oxide AlGaP, Magnesium doped GaAsP, Magnesium doped AlAsP, Magnesium doped AlGaInP, Magnesium doped AlGaInAs, Magnesium doped InGaAsP, Magnesium doped AlGaAsP, Magnesium doped AlInAsP, Magnesium doped InGaAlAsP, Zinc doped AlAs, Zinc doped GaP, Zinc doped AlP, Zinc doped AlGaAs Zinc doped InAlAs, zinc doped InGaP, zinc doped InAlP, zinc doped AlGaP, zinc doped GaAsP, zinc doped AlAsP, zinc doped AlGaInP, zinc doped AlGaInAs, zinc doped InGaAsP, zinc doped AlGaAsP, zinc doped AlInAsP, zinc doped InGaAlAsP, carbon It is formed of any one of the group InP, carbon-doped InAs, carbon-doped GaAs, carbon-doped InAsP, magnesium-doped InP, magnesium-doped InAs, magnesium-doped GaAs, magnesium-doped InAsP, zinc-doped InAs, zinc-doped GaAs, and zinc-doped InAsP. A light emitting diode structure characterized by that.   2. The light emitting diode structure of claim 1, wherein the non-alloy ohmic contact layer comprises a plurality of recesses along an interface between the non-alloy ohmic contact layer and the first metal layer.   2. The light emitting diode structure according to claim 1, wherein the substrate is a conductive substrate.   The light emitting diode structure of claim 16, wherein the substrate is doped Ge, doped Si, doped GaAs, doped GaP, doped InP, doped InAs, doped GaN, doped AlGaAs, doped SiC, doped GaAsP, Mo, Cu, and A light emitting diode structure formed of any one of Al.   17. The light emitting diode structure according to claim 16, further comprising an insulating layer provided immediately above the substrate for the planar arrangement of the electrodes of the light emitting diode structure.   19. The light emitting diode structure according to claim 18, wherein the insulating layer is formed of silicon nitride (SiNx) or silicon oxide (SiOx).   2. The light emitting diode structure according to claim 1, wherein the substrate is a non-conductive substrate. 21. The light emitting diode structure according to claim 20, wherein the substrate is formed of any one of Ge, Si, GaAs, GaP, InP, InAs, GaN, AlN, AlGaAs, SiC, GaAsP, sapphire, glass, crystal, and ceramic. A light emitting diode structure.

Images