WO2015003564A1

WO2015003564A1 - Gallium nitride based light emitting diode and manufacturing method thereof

Info

Publication number: WO2015003564A1
Application number: PCT/CN2014/081230
Authority: WO
Inventors: 何安和; 林素慧; 彭康伟; 许圣贤; 林潇雄; 徐宸科
Original assignee: 厦门市三安光电科技有限公司
Priority date: 2013-07-08
Filing date: 2014-06-30
Publication date: 2015-01-15
Also published as: CN103367590A

Abstract

A GaN based light emitting diode and a manufacturing method thereof. A metal adhesion layer is additionally disposed between a conventional metal electrode layer and a semiconductor protection layer. The metal adhesion layer is well adhered to a material of the semiconductor protection layer, which avoids protection layer falling caused by poor adherence of a conventional metal electrode surface layer to the material of the semiconductor protection layer, thereby effectively protecting a bottom layer metal electrode.

Description

Gallium nitride based light emitting diode and manufacturing method thereof

[1] Technical field

[2] The present invention relates to a gallium nitride based light emitting diode and a method of fabricating the same, and more particularly to a gallium nitride based high brightness light emitting diode having a metal adhesion layer and a method of fabricating the same.

[3] Background Art

[4] Light Emitting Diode (LED) is a semiconductor light-emitting device made by the principle of semiconductor P-N junction electroluminescence. LEDs have the advantages of high brightness, low power consumption, long life, low operating voltage, and easy integration. LED is a solid-state cold light source. It is the fourth generation of new light source after incandescent lamps, fluorescent lamps and high-intensity discharge (HID) lamps (such as high-pressure sodium lamps and gold lamps). It is recognized as the most developed in the 21st century. One of the high-tech fields of the future, due to the huge business opportunities of LED, is becoming a hot spot in the world.

[5] Currently, commercial blue-green LEDs are based on GaN III-V compound semiconductor materials.

Referring to FIG. 1, in a conventional dressing LED structure, a substrate 200 including an N-type layer 201 stacked from bottom to bottom, a light-emitting region 202, a P-type layer 203, a current spreading layer 204, a P electrode 205, and an N-type layer are provided. 201 N electrode 206 on the exposed surface. Due to the P electrode (usually Cr/Pt/Au,

Ni/Au, Ti/Au materials) inevitably absorb light, so that part of the light emitted by the light-emitting layer fails to be emitted, causing light loss and affecting the luminous efficiency of the chip. Currently, related technologies have passed under the metal electrode. The addition of a reflective film (such as a metal film or DBR) causes the light to be reflected back into the interior of the chip, and then the surface of the chip is emitted by one or more refractions, thereby increasing the luminous efficiency, which is extremely meaningful for improving the luminous efficiency of the LED.

By adding a chip having a reflective electrode formed of a metallic silver or aluminum reflective film, as shown in FIG. 1, the P electrode 205 and the N electrode 206 are replaced by a reflective metal electrode, that is, a reflective electrode light emitting diode chip is obtained. However, in this structure, Au is generally used as the surface metal for the electrode surface. Since Au and the semiconductor protective layer material (usually Si0 ₂ material) have poor adhesion, it is easy to fall off during the chip process, and an effective reflective metal sidewall protection cannot be formed. Therefore, in the aging of the chip package, the problem of abnormal light decay often occurs, especially in the environment of high temperature and high humidity, reflective metals such as silver and aluminum are more easily oxidized (see Figure 2). The light effect is reduced or even invalidated.

[7] Summary of the invention

[8] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a GaN-based high-brightness LED having a metal adhesion layer and a method of fabricating the same. The invention increases the adhesion of the metal electrode to the semiconductor protective layer covering the metal electrode by adding a mouth-shaped metal adhesion layer on the surface metal of the metal electrode, so that the semiconductor protection layer does not fall off in the subsequent chip process, thereby The effective lateral protection is formed, and the reflective metal in the metal electrode layer is prevented from coming into contact with the air to prevent oxidation, thereby improving the high temperature and high humidity resistance of the chip.

[9] The technical solution of the present invention is: a gallium nitride-based light emitting diode, comprising: a growth substrate; a light-emitting epitaxial layer on the growth substrate, which includes a first semiconductor layer, a light-emitting layer, and a second layer in order from bottom to top a semiconductor layer; a gate on the second semiconductor layer and extending to the first semiconductor layer such that a portion of the first semiconductor layer is exposed; a transparent current spreading layer over the second semiconductor layer, at least a portion of the region and the second semiconductor Layer contact; a metal electrode layer is divided into a first metal electrode layer and a second metal electrode layer, the first metal electrode layer is located on the transparent current extension, and the second metal electrode layer is located on the exposed first semiconductor layer; The layers are respectively located on the first metal electrode layer and the second metal electrode layer; a semiconductor protective layer is located on the above structure, and the surface of the metal electrode layer is exposed through the semiconductor protective layer and the metal adhesion layer opening; the metal adhesion The layer corresponds to the position of the mouth of the semiconductor protective layer, and the size is substantially the same.

[10] In the present invention, preferably, the first metal electrode layer is in contact with a portion of the second semiconductor layer in the form of a transparent current spreading port.

[11] The present invention also provides a method for fabricating a gallium nitride-based light-emitting diode, which mainly includes the following process steps: 1) providing a growth substrate; 2) fabricating a light-emitting epitaxial layer on the growth substrate, which is sequentially The first semiconductor layer, the light emitting layer, and the second semiconductor layer are included; 3) etching at least one opening from the second semiconductor layer by an etching process, and extending to the first semiconductor layer such that a portion of the first semiconductor layer is exposed; 4) Forming a current spreading layer on the second semiconductor layer; 5) forming first and second metal electrode layers by electron beam evaporation or ion sputtering, respectively covering the current spreading layer and the exposed first semiconductor layer; a metal adhesion layer is formed on the first and second metal electrode layers by electron beam evaporation or ion sputtering; 7) depositing a semiconductor protective layer on the above structure, and using the same mask A wet or dry etching process is used to simultaneously produce a semiconductor protective layer and a metal adhesion layer to expose the surface of the metal electrode layer; 8) thinning and dicing into a single core particle; wherein, the metal The adhesive layer corresponds to the position of the mouth of the semiconductor protective layer, and the size is substantially the same.

[12] In the invention, preferably, the metal adhesion layer has a ring shape and a ring width of 3 to 15 μ ηι and a thickness of 50 1000 A.

[13] In the invention, preferably, the first and second metal electrode layers and the metal adhesion layer are produced by the same electron beam evaporation or ion sputtering process.

[14] In the present invention, preferably, the wet etching solution used for the semiconductor protective layer and the metal adhesion layer is the same.

[15] In the present invention, preferably, the dry etching used to form the semiconductor protective layer and the metal adhesion layer is the same.

[16] In the present invention, preferably, the growth substrate material is selected from sapphire (A1 ₂ 0 ₃ ) or silicon carbide (SiC).

) or gallium nitride (GaN) or silicon (Si).

[17] In the present invention, preferably, the transparent conductive layer material is selected from nickel/gold alloy or nickel/indium tin oxide alloy or indium tin oxide or zinc oxide or In dilute zinc oxide or A1 miscellaneous zinc oxide or Ga mis. Zinc oxide or one of any combination of the foregoing.

[18] In the present invention, preferably, the first and second metal electrode layers are composed of a plurality of metal laminates, and the reflective metal in the metal laminate may be selected from the group consisting of A1 or Ag or an AlAg alloy, and the reflective metal is located on the laminate. The first or second layer, such as a metal laminate, may be selected from Al/Pt/Au, Ag/Pt/Au, Al/Ti/Pt/Au, Al/Cr/Pt/Au, Cr/Al/Pt/Au, Cr. /Ag/Cr/Pt/Au combination, thickness range is l~50um.

[19] In the present invention, preferably, the metal adhesion layer material is selected from Ti or ruthenium or Cr or Ni or one of any combination of the foregoing.

[20] In the present invention, preferably, the semiconductor protective layer material is selected from 810 ₂ or 81 ₃ or A1 ₂ 0 ₃ or Ti0 ₂ or one of any combination of the foregoing.

[21] Compared with the prior art, the beneficial effects of the present invention are: enhancing the adhesion between the metal electrode and the semiconductor protective layer covering the metal electrode by adding a metal adhesion layer on the metal electrode layer, so that the semiconductor The protective layer does not fall off in the subsequent chip process, thereby forming effective lateral protection, avoiding the contact of the reflective metal and the air in the metal electrode layer, preventing oxidation, and improving the high temperature and high humidity resistance of the chip. Other features and advantages of the invention will be set forth in the description which follows, and The objectives and other advantages of the invention may be realized and obtained in the form of the description particularly pointed in the claims.

[23] While the invention will be described in conjunction with the exemplary embodiments and the methods of the invention, it is understood that the invention is not intended to limit the invention. Rather, the invention is to cover all alternatives, modifications, and equivalents of the scope of the invention as defined by the appended claims.

[24] BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to provide a further understanding of the invention, and are not intended to limit the invention. In addition, the drawing figures are a summary of the description and are not drawn to scale.

[26] Figure 1 is a schematic view showing the structure of a conventional packaged gallium nitride based light emitting diode.

[27] Figure 2 is an unusual schematic diagram of a conventional LED electrode with a reflective metal electrode in a high temperature and high humidity aging experiment.

3 is a cross-sectional view showing the fabrication of a gallium nitride based light emitting diode according to Embodiment 1 of the present invention.

4 is a schematic flow chart of fabricating a gallium nitride based light emitting diode according to Embodiment 2 of the present invention.

5 to FIG. 13 are schematic cross-sectional views showing a process for fabricating a gallium nitride based light emitting diode according to Embodiment 2 of the present invention.

[31] Parts symbol description in the figure:

[32] 100: growth substrate; 101: first semiconductor layer - N-type layer; 102: light-emitting layer; 103: second semiconductor layer - p-type layer; 104: current spreading layer; 105: P electrode of the first metal layer 106: N electrode of the first metal layer; 107: metal adhesion layer; 108: semiconductor protective layer;

[33] 200: substrate; 201: N-type layer; 202: illuminating region; 203: P-type layer; 204: current spreading layer; 205: P electrode; 206: N electrode.

[34] Specific implementation

[35] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, in which the present invention can be applied to the technical problems, and the implementation of the technical effects can be fully understood and implemented. It should be noted that, as long as the conflict is not formed, various embodiments and embodiments in the present invention The various features can be combined with each other, and the resulting technical solutions are within the scope of the present invention.

[36] Example 1

As shown in FIG. 3, the gallium nitride-based light emitting diode having a metal adhesion layer structure includes: a growth substrate 100, an N-type layer 101, a light-emitting layer 102, a P-type layer 103, and a current spreading layer 104. The P electrode 105 of the first metal electrode layer, the N electrode 106 of the second metal electrode layer, the metal adhesion layer 107, and the semiconductor protective layer 108.

[38] Specifically, in the above GaN-based LED structure, the growth substrate 100 is a sapphire substrate; the N-type layer 101 is formed on the sapphire substrate 100; the light-emitting region 102 is formed on the N-type layer 101; The layer 103 is formed on the light-emitting region 102; the current spreading layer 104 is formed on the P-type layer 103, and the material thereof is generally selected from nickel/gold alloy, nickel/indium tin oxide alloy, indium tin oxide, zinc oxide, and Indigo oxidation. One or a combination of zinc, A1 miscellaneous zinc oxide, Ga miscellaneous zinc oxide, in this embodiment, indium tin oxide (ITO) is used; the first and second metal electrode layers 105, 106 are respectively formed on ITO transparent The current spreading layer is on the exposed N-type layer; the reflective metal layer is a plurality of metal layers, wherein the reflective metal material generally selects a high reflectivity metal such as aluminum (A1) or silver (Ag) or nickel (Ni) In a preferred embodiment of the present invention, A1 is selected as the metal reflective layer, Al/Ti/Pt/Au is selected as the first and second metal electrode layers, and the metal adhesion layer 107 is formed on the first and second metals. On the electrode layer, the metal adhesion layer material can be Selection A1 or Ti or TiN Cr or one or any combination of the foregoing, in the present embodiment selection Ti embodiment; semiconductor protective layer 108 is formed on the Ti metal adhesion layer, the protective layer may be a semiconductor selected Si0 ₂ or Si ₃ N ₄ or A1 ₂ 0 ₃ or Ti0 ₂ or one of a combination of any of the foregoing, in the embodiment chosen Si0 ₂ in the present embodiment.

[39] The Ti metal adhesion layer and the SiO ₂ semiconductor protective layer are both provided with a mouth to expose the surface of the metal electrode layer, and the position of the mouth of the metal electrode is correspondingly up and down, and the size is substantially uniform, and the Ti metal adhesion layer after the mouth is ring-shaped. , the ring width is controlled in the range of 3~15 μ ηι, and the thickness is controlled in the range of 50~1000 people. Because the ring width or / and the thickness is too small, it will have good adhesion to Si0 ₂ ; Large, it will affect the wire area of the metal electrode layer. If the thickness is too large, metal materials will be wasted. In the present embodiment, it is preferred that the Ti metal adhesion layer has a ring width of 5 μηη and a thickness of 200 persons.

[40] Ti is selected as the metal adhesion layer, mainly based on its good adhesion to SiO ₂ and its own thermal stability, thus enhancing the adhesion between the metal electrode and the semiconductor protective layer overlying it. Sex, so that the semiconductor protective layer will not fall off in the subsequent process, thus forming effective lateral protection, thus avoiding The reflective metal in the metal electrode layer is prevented from coming into contact with the air to prevent oxidation, thereby improving the high temperature and high humidity resistance of the chip.

[41] Example 2

[42] Correspondingly, the embodiment provides a method for manufacturing a gallium nitride based light emitting diode having a metal adhesion layer structure. For the specific process, please refer to FIG. 4, which includes the following process steps:

[43] S11, providing a growth substrate;

[44] S12, a long-emitting epitaxial layer on the growth substrate, wherein the epitaxial layer is an N-GaN layer, a light-emitting layer, and a P-GaN layer from bottom to top;

[45] S13, etching a partially exposed N-GaN layer mesa from the P-GaN layer by an etching process;

[46] S14, forming a transparent current spreading layer on the P-GaN layer;

[47] S15, forming first and second metal electrode layers on the current spreading layer and the exposed N-GaN layer;

[48] S16, forming a metal adhesion layer on the first and second metal electrodes;

[49] S17, depositing a semiconductor protective layer on the above structure;

[50] S18, through the same mask operation, using a wet or dry etching process, simultaneously preparing a semiconductor protective layer and a metal adhesion layer to expose the surface of the metal electrode layer as a wire bonding area;

[51] S19, thinned and cracked into a single core.

[52] FIG. 5 to FIG. 12 are schematic cross-sectional views showing a manufacturing process of an LED according to an embodiment of the present invention, specifically:

[53] As shown in FIG. 5, first, a growth substrate 100 is provided. In this embodiment, the growth substrate 100 is made of sapphire for forming an epitaxial substrate of a GaN-based blue diode; however, it should be recognized that the growth The substrate 100 can also be silicon carbide or gallium nitride or silicon.

As shown in FIG. 6, the epitaxial layer is epitaxially grown by MOCVD on the growth substrate 100, and the luminescent epitaxial layer is an N-GaN layer 101, a luminescent layer 102, and a P-GaN layer 103 from bottom to top; as shown in FIG. A partially exposed N-GaN layer 101 mesa is etched from the P-GaN layer 103 by an ICP etching process; as shown in FIG. 8, a transparent current spreading layer 104 is formed on the above structure, and a transparent conductive layer material is selected from a nickel/gold alloy. Nickel/indium tin oxide alloy, indium tin oxide, zinc oxide, Indigo zinc oxide, A1 miscellaneous zinc oxide, Ga miscellaneous zinc oxide, or a combination thereof; as shown in FIG. 9, electron beam evaporation or In the ion sputtering method, a first metal electrode layer (P electrode) 105 is formed on the transparent current spreading layer and the bare N-GaN, respectively. a second metal electrode layer (N electrode) 106, a metal electrode layer material selected from AlCr/Pt/Au; as shown in FIG. 10, a first metal electrode layer (P electrode) 105 and a second metal electrode layer (N electrode) are fabricated After 106, no metal stripping operation is required, and the Ti metal adhesion layer 107 is continuously evaporated thereon; as shown in FIG. 11, the semiconductor protection layer 108 is formed on the above structure, and the semiconductor protection layer material is selected from Si0 ₂ ; As shown, through the same mask operation, a wet etching process is used, the etching solution is selected as a buffered oxide etchant BOE solution, and a part of the semiconductor protective layer and the titanium metal adhesion layer are etched away to obtain a semiconductor protective layer and a metal adhesion layer. The surface of the first metal electrode layer (P electrode) 105 and the second metal electrode layer (N electrode) 106 are exposed; it should be noted that the wet etching solution should be selected to etch the metal adhesion layer, but the metal electrode cannot be etched. A solution of the layer is preferred to avoid damage to the metal electrode layer. As shown in FIG. 13, the sapphire substrate 100 is thinned to a thickness of 80 to 250 μm, and split to form a single core pellet, thereby producing a gallium nitride-based light emitting diode having a metal adhesion layer structure.

[55] Example 3

[56] Different from Embodiment 2, in this embodiment, a gallium nitride-based light emitting diode having a metal adhesion layer structure is selected, Cr is used as the metal adhesion layer, and A1 ₂ 0 ₃ is selected as the semiconductor protection layer; The opening of the semiconductor protective layer is realized by the same mask and ICP dry etching process.

[57] In summary, the present invention provides a GaN-based light emitting diode and a method of fabricating the same, which adds a metal adhesion layer between a conventional metal electrode layer and a semiconductor protective layer due to a metal adhesion layer and semiconductor protection. The adhesion of the layer material is good, and the peeling of the protective layer caused by the poor adhesion between the surface layer of the conventional metal electrode (such as Au) and the protective layer material is avoided, thereby effectively protecting the underlying metal electrode.

Claims

claims

[1] A gallium nitride-based light-emitting diode, including:

a growth substrate;

The luminescent epitaxial layer is located on the growth substrate and includes a first semiconductor layer, a luminescent layer and a second semiconductor layer from bottom to top;

An opening is located on the second semiconductor layer and extends to the first semiconductor layer, leaving part of the first semiconductor layer exposed;

A transparent current spreading layer is located on the second semiconductor layer, and at least a partial area is in contact with the second semiconductor layer;

A metal electrode layer is divided into a first metal electrode layer and a second metal electrode layer. The first metal electrode layer is located on the transparent current extension, and the second metal electrode layer is located on the exposed first semiconductor layer; a metal adhesion layer is located on On the first metal electrode layer and the second metal electrode layer; a semiconductor protective layer is located on the above structure, and the surface of the metal electrode layer is exposed through the opening of the semiconductor protective layer and the metal adhesion layer;

It is characterized in that: the opening positions of the metal adhesion layer and the semiconductor protective layer correspond up and down, and the sizes are generally the same.

[2] A gallium nitride-based light-emitting diode according to claim 1, characterized in that: the first metal electrode layer contacts part of the second semiconductor layer through a transparent current expansion opening.

[3] A method of manufacturing a gallium nitride-based light-emitting diode, which mainly includes the following process steps:

1) Provide a growth substrate;

2) Make a luminescent epitaxial layer on the growth substrate, which includes a first semiconductor layer, a luminescent layer and a second semiconductor layer from bottom to top;

3) Use an etching process to etch at least one opening from the second semiconductor layer and extend it to the first semiconductor layer, leaving part of the first semiconductor layer exposed;

4) Make a current spreading layer on the second semiconductor layer;

5) Use electron beam evaporation or ion sputtering technology to make the first and second metal electrode layers, covering the current expansion layer and the exposed first semiconductor layer respectively;

6) Use electron beam evaporation or ion sputtering process to make gold on the first and second metal electrode layers. Belongs to the adhesion layer;

7) Deposit a semiconductor protective layer on the above structure, and use the same photomask operation to use a wet or dry etching process to simultaneously prepare the semiconductor protective layer and the metal adhesion layer, exposing the surface of the metal electrode layer;

8) Thinning and splitting into single core particles;

[4] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The metal adhesion layer is used to increase the adhesion between the metal electrode and the semiconductor protective layer.

[5] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The metal adhesion layer is ring-shaped, and the ring width is 3~15 μm.

[6] A method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The thickness of the metal adhesion layer is 50~1000 people.

[7] A method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The first and second metal electrode layers and metal adhesion layers are produced through the same electron beam evaporation or ion sputtering process.

[8] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The wet etching solution used to make the semiconductor protective layer and the metal adhesion layer is the same.

[9] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The dry etching process used to make the semiconductor protective layer and the metal adhesion layer is the same.

[10] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The metal adhesion layer material is selected from Ti or TiN or Cr or Ni or any combination of the above.

[11] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The semiconductor protective layer material is selected from Si0 ₂ or Si ₃ N ₄ or A1 ₂ 0 ₃ or Ti0 ₂ or any combination of the above.

[12] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The growth substrate material is sapphire (A1 ₂ 0 ₃ ) or silicon carbide (SiC) or gallium nitride ( GaN) or silicon (Si).

[13] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The transparent conductive layer material is selected from nickel I gold alloy or nickel I indium tin oxide alloy or indium tin oxide or zinc oxide or In zinc oxide or Al zinc oxide or Ga zinc oxide or any combination of the above. one.

[14] The method for manufacturing a gallium nitride-based light-emitting diode according to claim 3, characterized in that

: The metal electrode layer is selected from Cr or Pt or Au or Ti or A1 or Ag or any combination of the above.