CN101212011A - Light emitting diode and method for manufacturing the same - Google Patents

Abstract

A Light Emitting Diode (LED) and a method of manufacturing the same. The light emitting diode at least comprises: a conductive substrate having a first surface and a second surface opposite to each other; a metal bonding layer arranged on the first surface of the conductive substrate; a metal reflecting layer is jointed on the metal jointing layer; an N-type semiconductor layer arranged on the metal reflecting layer; an active layer arranged on the N-type semiconductor layer; a P-type semiconductor layer arranged on the active layer; a window layer disposed on the P-type semiconductor layer, wherein the window layer has a thickness of 50 μm or more and is made of transparent conductive material; and a P-type electrode disposed on the window layer.

Description

Light-emitting diode and its manufacturing method

technical field

The present invention relates to a light-emitting diode (LED) and its manufacturing method, and in particular to a high-efficiency light-emitting diode and its manufacturing method.

Background technique

In the production of light-emitting diodes, III-V semiconductor compounds, such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AlInGaN) and other materials, is a fairly common material. Such light-emitting epitaxial structures composed of III-V semiconductor compounds are mostly grown on non-conductive sapphire substrates, which are different from conductive substrates used in other light-emitting devices. Since the sapphire substrate is an insulator, electrodes cannot be directly fabricated on the sapphire substrate. Therefore, when making the electrodes of the light-emitting diodes composed of III-V semiconductor compounds, the electrodes must be directly in contact with the P-type semiconductor layer and the N-type semiconductor layer respectively, so as to complete the manufacture of this type of light-emitting element.

Generally, the traditional light-emitting diode structure uses N-type gallium arsenide (GaAs) as the primary substrate (Growth Substrate) material. Since the original substrate composed of N-type gallium arsenide absorbs light, among the photons generated by the active layer of the light-emitting diode, most of the photons towards the original substrate will be absorbed by the original substrate, which seriously affects the performance of the light-emitting diode element. Luminous efficiency.

In order to avoid the light-absorbing problem of the substrate of the light-emitting diode, I. Pollentirer and others of the University of Gent in Belgium published the technology of peeling the GaAs light-emitting diode chip from the GaAs substrate and directly bonding it to the silicon (Si) substrate in the Electronics Letters journal in 1990. . In addition, the United States Hewlett-Packard Company disclosed in its U.S. Patent No. 5,376,580 (application date: March 19, 1993) that aluminum gallium arsenide (AlGaAs) light-emitting diode chips are directly bonded to other substrates after peeling off the gallium arsenide substrate. technology. However, the disadvantage of US Pat. No. 5,376,580 is that the semiconductor is used as the bonding medium, so the alignment of the crystal lattice between the two bonded semiconductor wafers must be considered, and the process is difficult, resulting in a decrease in yield.

Contents of the invention

Therefore, the object of the present invention is to provide a light-emitting diode with a thicker window layer (WindowLayer), which is helpful for current diffusion, and can improve light extraction efficiency, so as to achieve the effect of increasing the brightness of the light-emitting diode.

Another object of the present invention is to provide a light-emitting diode with a P-type upward structure, so it is easier to roughen the surface of the element, so that the light extraction rate can be improved, and the luminance can be improved.

Another object of the present invention is to provide a method of manufacturing a light emitting diode, which grows a thicker window layer on the native substrate, which can be used as a temporary support structure during the subsequent process of the light emitting diode, so the removal of the native substrate, The follow-up process of the light-emitting epitaxy structure and the necessary process of the permanent substrate can be completed before the wafer bonding process. In this way, the process window can be greatly increased without being limited to a lower bonding temperature, and the process window can be effectively improved. Process yield.

Another object of the present invention is to provide a method for manufacturing a light-emitting diode, which can use an alloy with a lower melting point as a chip bonding medium, thereby effectively improving the reliability of the chip bonding process.

According to the above object of the present invention, a light emitting diode is proposed, comprising at least: a conductive substrate having opposite first and second surfaces; a metal bonding layer disposed on the first surface of the conductive substrate; a metal reflective layer , bonded on the metal bonding layer; an N-type semiconductor layer, set on the metal reflective layer; an active layer, set on the N-type semiconductor layer; a P-type semiconductor layer, set on the active layer; a window layer, It is arranged on the P-type semiconductor layer, wherein the thickness of the window layer is more than 50 μm, and the window layer is made of transparent conductive material; and a P-type electrode is arranged on the window layer.

According to a preferred embodiment of the present invention, the thickness of the above-mentioned window layer is between 50 μm and 200 μm.

According to the purpose of the present invention, a method for manufacturing a light-emitting diode is proposed, at least including: providing a primary substrate; forming an N-type semiconductor layer on the primary substrate; forming an active layer on the N-type semiconductor layer; forming a P-type semiconductor Layer on the active layer; form a window layer on the P-type semiconductor layer, wherein a thickness of the window layer is more than 50 μm, and the window layer is made of transparent conductive material; remove the original substrate; form a P-type electrode on the Part of the window layer; forming a metal reflective layer on the N-type semiconductor layer, wherein the metal reflective layer and the active layer are located on opposite sides of the N-type semiconductor layer; providing a conductive substrate, wherein the conductive substrate has a first surface opposite and the second surface, and a metal bonding layer is provided on the first surface of the conductive substrate; and a bonding step is performed to bond the metal reflective layer and the metal bonding layer.

According to a preferred embodiment of the present invention, the step of forming the window layer at least includes forming a part of the thickness of the window layer by a metalorganic chemical vapor deposition method, and forming another part of the thickness of the window layer by a vapor phase epitaxy method.

Description of drawings

1 to 4 are cross-sectional views of the manufacturing process of a light emitting diode according to a preferred embodiment of the present invention.

Detailed ways

The invention discloses a light-emitting diode and its manufacturing method, which has a thicker window layer, so that the current diffusion can be enhanced, and the light extraction efficiency can be improved, which is more conducive to the roughening treatment of the surface of the element, and further improves the light extraction rate to achieve an improvement. Efficacy of the luminous brightness of light-emitting diode components. In addition, all necessary processes can be completed before wafer bonding, so the bonding temperature is more flexible, and a wider process window can be obtained. Furthermore, an alloy with a lower melting point can be used as the die bonding medium, thereby improving the reliability of the die bonding process. In order to make the description of the present invention more detailed and complete, reference may be made to the following description in conjunction with FIG. 1 to FIG. 4 .

Please refer to FIG. 1 to FIG. 4 , which are cross-sectional views of the manufacturing process of a light emitting diode according to a preferred embodiment of the present invention. In the present invention, when fabricating the light emitting diode element, the original substrate 100 is firstly provided, and then the N-type semiconductor layer 106 can be directly grown on the surface of the original substrate 100 by using, for example, an epitaxial method. In one embodiment of the present invention, the N-type contact layer 104 can be optionally formed on the surface of the native substrate 100 first, and then the N-type semiconductor layer 106 is epitaxially grown on the N-type contact layer 104, so as to improve the electrical resistance of the device. sexual quality. In another embodiment of the present invention, the etch stop layer 102 may be selectively deposited on the surface of the original substrate 100, and then the N-type contact layer 104 and the N-type semiconductor layer are sequentially epitaxially grown on the etch stop layer 102. layer 106 to facilitate subsequent removal of the native substrate 100 , as shown in FIG. 1 . In this preferred embodiment, an etch stop layer 102 and an N-type contact layer 104 are sequentially formed on the original substrate 100 , and an N-type semiconductor layer is formed on the N-type contact layer 104 . The material of the N-type contact layer 104 can be, for example, N-type Gallium Arsenide (GaAs), N-type Gallium Arsenide Phosphide (GaAsP), or N-type Aluminum Gallium Indium Phosphide (AlGaInP). The material of the N-type semiconductor layer 106 can be, for example, N-type aluminum gallium indium phosphide [(Al _x Ga _{1- x} ) _0.5 In _0.5 P]. Next, the active layer 108 is grown on the N-type semiconductor 106 by epitaxy, for example, where the active layer 108 may be, for example, a multiple quantum well (Multiple Quantum Well; MQW) structure. Then use, for example, an epitaxy method to grow a P-type semiconductor layer 110 on the active layer 108, wherein the material of the P-type semiconductor layer 110 can be, for example, P-type aluminum gallium indium phosphide [(Al _x Ga _1-x ) _0.5 In _0.5 P ]. Subsequently, a window layer 112 is formed on the P-type semiconductor layer 110 to form the structure shown in FIG. 1 . The window layer 112 is composed of a transparent conductive material, and the material of the window layer 112 can be, for example, gallium phosphide (GaP), gallium arsenide phosphide (GaAsP), or aluminum gallium arsenide (AlGaAs). In the present invention, it is preferable to use a two-stage epitaxial deposition method when forming the window layer 112 . In a preferred embodiment of the present invention, the first film having a partial thickness of the window layer 112 is formed by Metal Organic Chemical Vapor Deposition (MOCVD), and then Vapor Phase Epitaxy (Vapor Phase Epitaxy; VPE) to form a second film with the remaining thickness of the window layer 112 on the first film. In the present invention, the thickness of the window layer 112 is relatively large, preferably more than 50 μm, for example, between 50 μm and 200 μm, so as to provide sufficient structural support for the wafer for subsequent manufacturing processes.

In the present invention, because the thickness of the window layer 112 is relatively large, it can be made into a P-type upward structure, which not only facilitates current diffusion, but also improves light extraction efficiency. In addition, since the thicker window layer 112 is located above, it is beneficial to roughen the surface of the element, which can further increase the light extraction rate, thereby improving the brightness of the element.

After the window layer 112 is fabricated, the original substrate 100 is removed by, for example, etching, using the window layer 112 as a structural support. At this time, if the etching stop layer 102 is provided on the surface of the native substrate 100 , the etching stop layer 102 can be used as an etching end point. In the present invention, after the original substrate 100 is removed, the etch stop layer 102 is preferably removed together. In this preferred embodiment, after the original substrate 100 is removed, since the N-type contact layer 104 is formed on the etching stop layer 102, the N-type contact layer 104 is exposed after the original substrate 100 is removed. as shown in picture 2. On the other hand, if the N-type contact layer 104 is not provided, the N-type semiconductor layer 106 is exposed after the native substrate 100 is removed.

Since the structural strength provided by the thicker window layer 112 is sufficient to support the epitaxial structure for subsequent manufacturing processes, the native substrate 100 can be removed smoothly under the support of the window layer 112 .

Subsequent processing may be performed after the native substrate 100 is removed. For example, optionally, the N-type contact layer 104 is first patterned, and then the metal material layer 138 is formed on the N-type contact layer 104 to form a stacked structure of the N-type metal contact layer 134, so as to reduce the number of N-type metal contact layers 134. The light absorption effect, and form a mesh or distributed point electrode structure, to take into account the ohmic contact quality and light extraction rate. The material of the metal material layer 138 can be, for example, a gold-germanium alloy. A transparent conductive layer 116 is then formed to cover the exposed N-type semiconductor layer 106 and the N-type metal contact layer 134 having a grid-like or dot-like electrode structure. In the present invention, the surface 118 of the transparent conductive layer 116 is bonded to the N-type semiconductor layer 106 . The material of the transparent conductive layer 116 can be, for example, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), indium tin oxide (ITO), cadmium tin oxide (CTO), copper aluminum oxide (CuAlO ₂ ), copper gallium oxide (CuGaO ₂ ), or strontium gallium oxide (SrCu ₂ O ₂ ). Next, a metal reflective layer 120 can be formed to cover the surface of the transparent conductive layer 116 , wherein the metal reflective layer 120 is located on the other surface of the transparent conductive layer 116 opposite to the surface 118 , as shown in FIG. 3 . In other embodiments of the present invention, the fabrication of the transparent conductive layer 116 and the N-type metal contact layer 134 may be omitted, and the metal reflective layer 120 is directly formed to cover the exposed N-type semiconductor layer 106 . The material of the metal reflective layer 120 can be, for example, gold (Au), aluminum (Al), silver (Ag), chromium (Cr) or nickel (Ni). In addition, a diffusion barrier layer 122 can also be selectively formed to cover the metal reflective layer 120 , as shown in FIG. 3 . The material of the diffusion barrier layer 122 can be, for example, molybdenum (Mo), platinum (Pt), tungsten (W), indium tin oxide, zinc oxide or manganese (Mn). In addition, the P-type electrode 114 is formed on a portion of the window layer 112 by, for example, vapor deposition.

At the same time, a permanent substrate such as a conductive substrate 124 is provided. The conductive substrate 124 is preferably made of materials with high electrical and thermal conductivity, wherein the material of the conductive substrate 124 can be, for example, silicon (Si), germanium (Ge), silicon carbide (SiC), or aluminum nitride (AlN). In an embodiment of the invention, the metal bonding layer 130 can be directly formed on the surface of the conductive substrate 124 . The metal bonding layer 130 is preferably a metal with a lower melting point, wherein the material of the metal bonding layer 130 can be, for example, lead-tin alloy (PbSn), gold-germanium alloy (AuGe), gold-beryllium alloy (AuBe), gold-tin alloy (AuSn ), tin, indium (In) or palladium indium alloy (PdIn). In a preferred embodiment of the present invention, the ohmic contact layer 126 and the ohmic contact layer 128 can also be selectively disposed on the opposite surfaces of the conductive substrate 124, so that the ohmic contact layer 126 is interposed between the metal bonding layer 130 and the conductive substrate. 124, to further improve the electrical quality of the light-emitting diode element, as shown in FIG. 3 . The material of the ohmic contact layer 126 and the ohmic contact layer 128 can be, for example, titanium (Ti), nickel, gold, or tungsten.

In the present invention, since the window layer 112 has a greater thickness, the epitaxial wafer after removing the light-absorbing native substrate 100 can complete the required processing steps before the wafer bonding step, without being limited to a lower temperature. Depending on the temperature, the process window can be expanded and the process yield can be improved.

As shown in FIG. 3 and FIG. 4 , after the subsequent processing steps of the epitaxial structure wafer supported by the window layer 112 and the conductive substrate 124 are completed, the bonding step can be carried out, and the metal bonding layer 130 or the diffusion barrier layer 122 can be used. The metal bonding layer 130 on the conductive substrate 124 is used as a bonding medium to bond the metal reflective layer 120 and the conductive substrate 124 to complete the fabrication of the light emitting diode 132 . After bonding, the metal reflective layer 120 can be directly connected to the metal bonding layer 130 , or the metal reflective layer 120 can be indirectly connected to the metal bonding layer 130 through the diffusion barrier layer 122 , as shown in FIG. 4 .

In the present invention, the metal or alloy with a lower melting point is used as the bonding medium, so the bonding temperature is far lower than the traditional bonding temperature using semiconductors as the medium, which can improve the reliability of wafer bonding, and then achieve The purpose of improving manufacturing yield.

It can be seen from the above-mentioned preferred embodiments of the present invention that one advantage of the present invention is that the light-emitting diode of the present invention has a thicker window layer, which is helpful for current diffusion, and can improve light extraction efficiency, thereby achieving the effect of increasing the brightness of the light-emitting diode. .

It can be seen from the above-mentioned preferred embodiments of the present invention that another advantage of the present invention is that because the light-emitting diode of the present invention has a P-type upward structure, it is easier to roughen the surface of the element, thereby improving the light extraction rate, and further Luminous brightness can be improved.

It can be seen from the above-mentioned preferred embodiments of the present invention that another advantage of the present invention is that because the manufacturing method of the light-emitting diode of the present invention is to grow a thicker window layer on the original substrate, it can provide sufficient light-emitting diode during the subsequent process. Structural support, so the removal of the native substrate, the subsequent process of the light-emitting epitaxial structure, and the necessary process of the permanent conductive substrate can be completed before the wafer bonding process, so that it is not limited by the lower bonding temperature , which can greatly increase the process window and effectively improve the process yield.

It can be seen from the above-mentioned preferred embodiments of the present invention that another advantage of the present invention is that the method for manufacturing light-emitting diodes of the present invention can use metals or alloys with lower melting points as the medium for bonding chips, thus effectively improving chip bonding. process reliability.

Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Anyone with ordinary knowledge in this technical field may make various equivalents without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the attached claims of the application.

Claims (26)

1. light-emitting diode comprises at least:

One electrically-conductive backing plate has a relative first surface and a second surface;

One metallic bond layer is located on this first surface of this electrically-conductive backing plate;

One metallic reflector is bonded on this metallic bond layer;

One n type semiconductor layer is located on this metallic reflector;

One active layers is located on this n type semiconductor layer;

One p type semiconductor layer is located on this active layers;

One window layers is located on this p type semiconductor layer, and wherein a thickness of this window layers is more than the 50 μ m, and this window layers is made up of a transparent conductive material; And

One P type electrode is located on this window layers.

2. light-emitting diode as claimed in claim 1, the material that it is characterized in that this electrically-conductive backing plate is silicon, germanium, carborundum or aluminium nitride.

3. light-emitting diode as claimed in claim 1, the material that it is characterized in that this metallic bond layer are terne metal, gold-germanium alloy, golden beryllium alloy, gold-tin alloy, tin, indium or palladium indium alloy.

4. light-emitting diode as claimed in claim 1 is characterized in that the material of this metallic reflector is gold, aluminium, silver, chromium or nickel.

5. light-emitting diode as claimed in claim 1, the material that it is characterized in that this n type semiconductor layer are N type AlGaInP [(Al _xGa _1-x) _0.5In _0.5P], this active layers is a multiple quantum trap structure, and the material of this p type semiconductor layer is P type AlGaInP [(Al _xGa _1-x) _0.5In _0.5P].

6. light-emitting diode as claimed in claim 1, the material that it is characterized in that this window layers are gallium phosphide, gallium phosphide arsenic or aluminum gallium arsenide.

7. light-emitting diode as claimed in claim 1, the thickness that it is characterized in that this window layers is between 50 μ m to 200 μ m.

8. light-emitting diode as claimed in claim 1 is characterized in that also comprising at least:

One first ohmic contact layer is bonded on this first surface of this electrically-conductive backing plate, and between this electrically-conductive backing plate and this metallic bond layer; And

One second ohmic contact layer is bonded on this second surface of this electrically-conductive backing plate.

9. light-emitting diode as claimed in claim 8, the material that it is characterized in that this first ohmic contact layer and this second ohmic contact layer is titanium, nickel, gold or tungsten.

10. light-emitting diode as claimed in claim 1 is characterized in that also comprising at least a diffused barrier layer, between this metallic bond layer and this metallic reflector.

11. light-emitting diode as claimed in claim 10, the material that it is characterized in that this diffused barrier layer is molybdenum, platinum, tungsten, tin indium oxide, zinc oxide or manganese.

12. light-emitting diode as claimed in claim 1 is characterized in that also comprising at least a transparency conducting layer, is bonded on the surface of this metallic reflector.

13. light-emitting diode as claimed in claim 12, the material that it is characterized in that this transparency conducting layer are indium oxide, tin oxide, zinc oxide, tin indium oxide, cadmium tin, cupric oxide aluminium, cupric oxide gallium or strontium oxide strontia gallium.

14. light-emitting diode as claimed in claim 12 is characterized in that also comprising at least:

One N type contact layer is positioned on this n type semiconductor layer of part; And

One metal material layer is located on this N type contact layer, and wherein this N type contact layer and this metal material layer are folded between this N type semiconductive layer and this transparency conducting layer, and are embedded in this transparency conducting layer.

15. light-emitting diode as claimed in claim 14, the material that it is characterized in that this N type contact layer are N p type gallium arensidep, N type gallium phosphide arsenic or N type AlGaInP.

16. a manufacturing method for LED comprises at least:

One primary substrate is provided;

Form a n type semiconductor layer on this primary substrate;

Form an active layers on this n type semiconductor layer;

Form a p type semiconductor layer on this active layers;

Form a window layers on this p type semiconductor layer, wherein a thickness of this window layers is more than the 50 μ m, and this window layers is made up of a transparent conductive material;

Remove this primary substrate;

Form a P type electrode on this window layers of part;

Form a metallic reflector on this n type semiconductor layer, wherein this metallic reflector and this active layers are positioned at relative two sides of this n type semiconductor layer;

One electrically-conductive backing plate is provided, and wherein this electrically-conductive backing plate has a relative first surface and a second surface, and this first surface of this electrically-conductive backing plate is provided with a metallic bond layer; And

Carry out an applying step, so that this metallic reflector engages with this metallic bond layer.

17. manufacturing method for LED as claimed in claim 16, the material that it is characterized in that this metallic bond layer are terne metal, gold-germanium alloy, golden beryllium alloy, gold-tin alloy, tin, indium or palladium indium alloy.

18. manufacturing method for LED as claimed in claim 16, the material that it is characterized in that this window layers are gallium phosphide, gallium phosphide arsenic or aluminum gallium arsenide.

19. manufacturing method for LED as claimed in claim 16, the thickness that it is characterized in that this window layers is between 50 μ m to 200 μ m.

20. manufacturing method for LED as claimed in claim 16 is characterized in that also comprising at least before this metallic bond layer is set:

Form one first ohmic contact layer, be bonded on this first surface of this electrically-conductive backing plate, so that this first ohmic contact layer is between this electrically-conductive backing plate and this metallic bond layer; And

Form one second ohmic contact layer, be bonded on this second surface of this electrically-conductive backing plate.

21. manufacturing method for LED as claimed in claim 16 is characterized in that before the step that forms this n type semiconductor layer, also comprises at least forming a N type contact layer, wherein this N type contact layer is between this n type semiconductor layer and this primary substrate.

22. manufacturing method for LED as claimed in claim 21 is characterized in that also comprising at least forming a transparency conducting layer on this N type contact layer between the step of the step that removes this primary substrate and this metallic reflector of formation.

23. manufacturing method for LED as claimed in claim 22 is characterized in that also comprising at least between the step of the step that removes this primary substrate and this transparency conducting layer of formation:

This N type contact layer of patterning is to expose this n type semiconductor layer of part; And

Form a metal material layer on this N type contact layer, wherein this N type contact layer and this metal material layer are folded between this n type semiconductor layer and this transparency conducting layer.

24. manufacturing method for LED as claimed in claim 16 is characterized in that between the step and this applying step that form this metallic reflector, also comprises at least forming a diffused barrier layer on this metallic reflector.

25. manufacturing method for LED as claimed in claim 16 is characterized in that before the step that forms this n type semiconductor layer, also comprises at least forming an etch stop layer, wherein this etch stop layer is between this n type semiconductor layer and this primary substrate.

26. manufacturing method for LED as claimed in claim 16 is characterized in that the step that forms this window layers comprises at least:

Utilize a Metalorganic chemical vapor deposition mode to form a first film of this window layers, and this first film have a part of thickness of this window layers; And

One second film that utilizes gas phase crystal type of heap of stone to form this window layers is positioned on this first film, and this second film has another part thickness of this window layers.

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