CN106159043B

CN106159043B - Flip LED chip and forming method thereof

Info

Publication number: CN106159043B
Application number: CN201510152729.5A
Authority: CN
Inventors: 朱秀山; 徐慧文; 李智勇; 朱广敏; 余婷婷; 张宇; 李起鸣
Original assignee: Yingrui Photoelectric Technology (shanghai) Co Ltd
Current assignee: Yingrui Photoelectric Technology (shanghai) Co Ltd
Priority date: 2015-04-01
Filing date: 2015-04-01
Publication date: 2019-12-13
Anticipated expiration: 2035-04-01
Also published as: CN106159043A

Abstract

The invention provides a flip LED chip and a forming method thereof, wherein the forming method comprises the following steps: providing a substrate; forming an N-type semiconductor layer, an active layer and a P-type semiconductor layer; forming an opening exposing a part of the N-type semiconductor layer; p, N forming an electrode layer and an insulating reflecting layer; forming P, N an electrode structure. The flip LED chip comprises a substrate, an N-type semiconductor layer, an active layer and a P-type semiconductor layer; a P electrode layer is arranged on the P type semiconductor layer, and an N electrode layer is arranged on the N type semiconductor layer in the opening; the insulating reflecting layer covers the P-type semiconductor layer, the P electrode layer, the N-type semiconductor layer and the N electrode layer; and the P electrode structure is formed in the insulating reflecting layer and is electrically connected with the P electrode layer, and the N electrode structure is electrically connected with the N electrode layer. The flip LED chip has the beneficial effects that the insulating reflecting layer can reflect part of light to the substrate while playing a role of insulating and isolating, so that the light transmittance of the flip LED chip is increased.

Description

Flip LED chip and forming method thereof

Technical Field

the invention relates to the technical field of LED manufacturing, in particular to a flip LED chip and a forming method thereof.

Background

A Light Emitting Diode (LED) is a semiconductor solid-state Light Emitting device, which is manufactured by using the principle of semiconductor PN junction electroluminescence. The LED device has good photoelectric properties of low starting voltage, small volume, quick response, good stability, long service life, no pollution and the like, so the LED device has more and more extensive application in the fields of outdoor and indoor illumination, backlight, display, traffic indication and the like.

Generally, LED chips are classified into three types, i.e., a horizontal structure (front chip), a vertical structure (vertical chip), and a flip chip; the P, N electrode layers in the LED chip with the flip-chip structure are all located on the same side of the light emitting area, and light emitted by the active layer in the LED chip mainly escapes through the transparent sapphire layer, so that the LED chip is higher in light emitting efficiency.

However, even if the conventional LED chip is changed to the above-mentioned flip-chip structure, the light emitting efficiency is still not ideal.

Therefore, how to further improve the light emitting efficiency of the LED chip becomes one of the technical problems to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide a flip LED chip and a forming method thereof, so as to improve the luminous efficiency of the flip LED chip as much as possible.

In order to solve the above problems, the present invention provides a method for forming a flip LED chip, comprising:

Providing a substrate;

Sequentially forming an N-type semiconductor layer, an active layer and a P-type semiconductor layer on the substrate;

forming an opening exposing a part of the N-type semiconductor layer in the P-type semiconductor layer and the active layer;

Forming a P electrode layer on the P type semiconductor layer;

Forming an N electrode layer on the N-type semiconductor layer in the opening;

Covering an insulating reflecting layer on the P-type semiconductor layer, the P electrode layer, the N-type semiconductor layer and the N electrode layer;

and forming a P electrode structure electrically connected with the P electrode layer and an N electrode structure electrically connected with the N electrode layer in the insulating reflecting layer.

Optionally, after the step of forming the opening and before the step of forming the P electrode layer, the forming method further includes:

forming a transparent conducting layer with the work function larger than that of the P-type semiconductor layer on the P-type semiconductor layer;

The step of forming the P electrode layer includes: and forming a P electrode layer with the work function larger than that of the transparent conductive layer on the transparent conductive layer.

Optionally, the transparent conductive layer is made of indium tin oxide or zinc oxide.

Optionally, after the step of forming the P electrode layer and before the step of covering the insulating reflective layer, the forming method further includes:

Forming a conductive protection layer on the surface and the side wall of the P electrode layer;

The step of covering the insulating reflective layer includes: forming the insulating reflective layer on the conductive protection layer.

Optionally, the step of covering the insulating reflective layer includes:

covering the DBR reflective layer or the ODR reflective layer.

Optionally, the step of covering the insulating reflective layer includes: forming an insulating reflective layer with a thickness of 1-5 μm.

Optionally, the step of covering the insulating reflective layer includes: form a plurality of bilayer structures in proper order, bilayer structure is including the first reflection stratum and the second reflection stratum that form in proper order, the refracting index of second reflection stratum is less than the refracting index of first reflection stratum.

optionally, the step of covering the insulating reflective layer includes: and sequentially forming 5-30 layers of double-layer structures to form the DBR reflecting layer or the ODR reflecting layer.

optionally, the step of covering the insulating reflective layer includes: sequentially forming 14-16 layers of double-layer structures to form the DBR reflecting layer;

or sequentially forming 5-8 double-layer structures, and forming a metal reflecting layer on the surfaces of the 5-8 double-layer structures to form the ODR reflecting layer.

optionally, the first reflective layer is made of titanium oxide, and the second reflective layer is made of silicon dioxide.

Optionally, the insulating reflective layer is formed by reactive plasma deposition.

Optionally, the step of forming the P electrode structure and the N electrode structure in the insulating reflective layer includes:

etching the insulating reflecting layer to form a first opening exposing a part of the P electrode layer and a second opening exposing the N electrode layer in the insulating reflecting layer;

Filling metal in the first opening to form a first conductive pillar electrically connected with the P electrode layer; the first conductive column forms the P electrode structure;

Filling metal in the second opening to form a second conductive pillar electrically connected with the N electrode layer; the second conductive column forms the N electrode structure;

and forming lead patterns which respectively lead out the P electrode layer and the N electrode layer on the surface of the insulation reflecting layer.

optionally, the step of forming the second conductive pillar includes:

Sequentially forming chromium, aluminum, titanium, platinum, gold and nickel in the second opening to form the second conductive pillar.

A flip-chip LED chip comprising:

a substrate;

an N-type semiconductor layer formed on the substrate;

An active layer formed on the N-type semiconductor layer;

a P-type semiconductor layer formed on the active layer, the P-type semiconductor layer and the active layer having an opening therein exposing a portion of the N-type semiconductor layer;

A P electrode layer is arranged on the P type semiconductor layer, and an N electrode layer is arranged on the N type semiconductor layer in the opening;

the insulating reflecting layer covers the P-type semiconductor layer, the P electrode layer, the N-type semiconductor layer and the N electrode layer;

A P electrode structure formed in the insulating reflective layer and electrically connected to the P electrode layer;

And the N electrode structure is formed in the insulating reflecting layer and is electrically connected with the N electrode layer.

Optionally, a transparent conductive layer is formed between the P-type semiconductor layer and the P-electrode layer, and a work function of the transparent conductive layer is greater than that of the P-type semiconductor layer and smaller than that of the P-electrode layer.

optionally, a conductive protection layer is formed between the P electrode layer and the insulating reflective layer.

Optionally, the insulating reflective layer is a DBR reflective layer or an ODR reflective layer.

Optionally, the insulating reflective layer includes a plurality of double-layer structures, each double-layer structure includes a first reflective layer and a second reflective layer located on a surface of the first reflective layer, and a refractive index of the second reflective layer is lower than that of the second reflective layer of the first reflective layer.

Compared with the prior art, the technical scheme of the invention has the following advantages:

After forming a P electrode layer and an N electrode layer of a flip LED chip on a substrate, an insulating reflective layer is covered on the substrate, that is, an insulating reflective layer is formed on the formed P electrode layer, P type semiconductor layer, N electrode layer and N type semiconductor layer. In the subsequent steps, the P electrode structure and the N electrode structure are formed in the insulating reflective layer, that is, the insulating reflective layer serves to electrically isolate the P electrode structure from the N electrode structure. Meanwhile, the insulating reflecting layer is positioned above the active layer, and when the flip LED chip works, light rays emitted by the active layer in a direction away from the substrate are reflected by the insulating reflecting layer and then penetrate out of the substrate. That is, the insulating reflective layer also functions to reflect light to the substrate, which is advantageous to increase the light transmittance of the flip LED chip of the present invention.

Drawings

Fig. 1 to 13 are schematic structural diagrams of steps in an embodiment of a method for forming a flip LED chip according to the present invention.

Detailed Description

In operation, the light emitted from the prior art flip-chip LED chip is generally transmitted through the substrate. However, a part of the light may still leak from the direction away from the substrate, i.e., the back surface of the flip LED chip or be absorbed by the material layer on the back surface of the flip LED chip, which is not favorable for increasing the light transmittance of the formed flip LED chip.

Therefore, the invention provides a flip LED chip and a forming method thereof, wherein the forming method of the flip LED chip comprises the following steps:

Providing a substrate; sequentially forming an N-type semiconductor layer, an active layer and a P-type semiconductor layer on the substrate; forming an opening exposing a part of the N-type semiconductor layer in the P-type semiconductor layer and the active layer; forming a P electrode layer on the P type semiconductor layer; forming an N electrode layer on the N-type semiconductor layer in the opening; covering an insulating reflecting layer on the P-type semiconductor layer, the P electrode layer, the N-type semiconductor layer and the N electrode layer; and forming a P electrode structure electrically connected with the P electrode layer and an N electrode structure electrically connected with the N electrode layer in the insulating reflecting layer.

Through the above steps, after forming the P electrode layer and the N electrode layer of the flip LED chip on the substrate, an insulating reflective layer is covered on the substrate, that is, an insulating reflective layer is formed on the formed P electrode layer, P type semiconductor layer, N electrode layer, and N type semiconductor layer. In the subsequent steps, the P electrode structure and the N electrode structure are formed in the insulating reflective layer, that is, the insulating reflective layer serves to electrically isolate the P electrode structure from the N electrode structure. Meanwhile, the insulating reflecting layer is positioned above the active layer, and when the flip LED chip works, light rays emitted by the active layer in a direction away from the substrate are reflected by the insulating reflecting layer and then penetrate out of the substrate. That is, the insulating reflective layer also functions to reflect light to the substrate, which is advantageous to increase the light transmittance of the flip LED chip of the present invention.

in order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

referring to fig. 1 to 13, schematic structural diagrams of steps in an embodiment of a method for forming a flip-chip LED chip of the invention are shown.

Referring to fig. 1, a substrate 100 is provided; in the present embodiment, the material of the substrate 100 is sapphire (Al)₂O₃)。

however, the material of the substrate 100 is not limited in the present invention, and the material may be, for example, spinel (MgAl)₂O₄) SiC, ZnS, ZnO, GaAs, or the like.

After that, an N-type semiconductor layer, an active layer, and a P-type semiconductor layer are sequentially formed on the substrate 100. Specifically, in this embodiment, the N-type semiconductor layer is an N-type gallium nitride layer 110, the active layer is a multiple quantum well layer 120(MQW), and the P-type semiconductor layer is a P-type gallium nitride layer 130.

The N-type gallium nitride layer 110, the MQW layer 120 and the P-type gallium nitride layer 130 are all necessary structures of the flip-chip LED chip, and therefore the functions of the N-type gallium nitride layer 110, the MQW layer 120(MQW) and the P-type gallium nitride layer 130 are not described in detail in the present invention.

specifically, the N-type gallium nitride layer 110, the multiple quantum well layer 120, and the P-type gallium nitride layer 130 in this embodiment may be sequentially formed on the substrate 100 through an epitaxial process, and the N-type gallium nitride layer 110, the multiple quantum well layer 120, and the P-type gallium nitride layer 130 may have a single-layer or multi-layer structure.

For example, the P-type gallium nitride layer 130 may be formed of Mg-doped In-GaN, Mg-doped P-GaN, and Mg-doped Al-GaN sequentially formed on the multiple quantum well layer 120, the multiple quantum well layer 120 may be a quantum well structure formed of InGaN layers and GaN layers alternately stacked, and the N-type gallium nitride layer 110 may be formed of Si-doped GaN layers.

However, it should be noted that the materials and structures of the N-type gallium nitride layer 110, the mqw layer 120, and the P-type gallium nitride layer 130 are only examples, and the present invention is not limited thereto.

in this embodiment, after the step of forming the P-type gallium nitride layer 130 and before the step of forming the N electrode layer and the P electrode layer, the present embodiment further includes the following steps:

Referring to fig. 2, an opening 131 exposing a portion of the N-type gan layer 110 is formed in the P-type gan layer 130 and the mqw layer 120, so as to form a Mesa for fabricating a flip-chip LED chip. The Mesa exposes the N-type gan layer 110 for subsequent formation of an N-electrode layer electrically connected to the N-type gan layer 110.

in this embodiment, a plasma etching method may be adopted to remove a portion of the P-type gallium nitride layer material and the multiple quantum well layer material to form the opening 131. The etching method has strong anisotropy, and the edge of the formed opening 131 is relatively neat, so that the size of the opening 131 is easier to control.

Specifically, boron trichloride gas and chlorine gas can be used as plasma etching gas, and argon gas can be used as carrier gas of the etching gas.

however, it should be noted that the dry etching and the etching gas used in the dry etching are only an example of the present invention, and the present invention is not limited to how to form the opening 131, and other etching methods, such as wet etching, and the like, may be used to form the opening 131.

thereafter, referring to fig. 3, in the present embodiment, after forming the opening 131, the following steps are further included: forming a transparent conductive layer 140 with a work function larger than that of the P-type gallium nitride layer 130 on the P-type gallium nitride layer 130; the work function of the transparent conductive layer 140 is also smaller than the work function of a subsequently formed P electrode layer, and when the P electrode layer is formed subsequently, the P electrode layer is formed on the transparent conductive layer 140, that is, in this embodiment, by adding one transparent conductive layer 140, the work function of the transparent conductive layer 140 is between the P-type gallium nitride layer 130 and the subsequently formed P electrode layer, which is favorable for reducing the barrier height between the P-type gallium nitride layer 130 and the P electrode layer, and further favorable for reducing the ohmic contact size between the P-type gallium nitride layer 130 and the P electrode layer, so that the working performance of the flip LED chip formed by the present invention, for example, the working voltage of the flip LED chip, can be improved.

The transparent conductive layer 140 has conductivity, and thus does not affect the electrical connection between the P-electrode layer formed later and the P-type gallium nitride layer 130.

In this embodiment, the transparent conductive layer 140 made of Indium Tin Oxide (ITO) material may be formed, and the transparent conductive layer 140 made of such material has a high transmittance, that is, a high transmittance in a visible light band, so that light emitted from the quantum well is not substantially blocked, and light loss is reduced.

moreover, the P-type gallium nitride layer 130 In this embodiment includes an In-GaN layer doped with Mg, that is, the transparent conductive layer 140 made of an indium tin oxide material and the P-type gallium nitride layer 130 both have In components, which is further beneficial to the interpenetration between the transparent conductive layer 140 made of indium tin oxide and the P-type gallium nitride layer 130, so as to be beneficial to reducing the resistivity of the transparent conductive layer 140, further help the current of the flip-chip LED chip during operation to spread on the transparent conductive layer 140, achieve the purpose of current expansion, prevent the occurrence of current congestion, increase the quantum efficiency, and further be beneficial to improving the working performance of the flip-chip LED chip.

In addition, the work function of the ito is generally between the work function of the P-type gan layer 130 and the work function of the P-electrode layer to be formed later, so that the purpose of reducing the height of the barrier between the P-type gan layer 130 and the P-electrode layer can be achieved.

It should be noted that, those skilled in the art should understand that the specific work function of the transparent conductive layer 140 can be adjusted by adjusting the process parameters during the formation thereof, and the present invention aims to make the work function of the formed transparent conductive layer 140 between the P-type gallium nitride layer 130 and the P-electrode layer formed subsequently, so the specific work function thereof should be adjusted according to the actual situation, which is not limited by the present invention.

In addition, the transparent conducting layer 140 made of the indium tin oxide material generally has a relatively small resistance, so that the current of the P electrode layer is spread on the transparent conducting layer 140 when the flip-chip LED chip works, which is favorable for achieving the purpose of current expansion, further preventing the occurrence of current congestion, increasing the quantum efficiency, and further being favorable for improving the working performance of the flip-chip LED chip.

However, the transparent conductive layer 140 that is formed of an ito material is not limited in the present invention, and in other embodiments of the present invention, other transparent and conductive materials may be used, such as zno, which has a similar work function to that of the ito, and is also beneficial to reducing the barrier height between the P-type gan layer 130 and the P-electrode layer formed subsequently, so as to improve the working performance of the flip-chip LED chip and reduce the working voltage of the flip-chip LED chip.

in this embodiment, the transparent conductive layer 140 can be formed to have a thickness within a range of 50 to 3000 angstroms. The transparent conductive layer 140 within this thickness range is not too thin to reduce the conductive capability (i.e. to increase the resistance), and is not too thick to absorb too much light, resulting in a reduction in the transmittance.

In this embodiment, the transparent conductive layer 140 may be formed by magnetron sputtering deposition (Sputter), which is relatively easy to control the formed transparent conductive layer 140. However, the forming method is not limited in the present invention, and other forming processes such as Reactive Plasma Deposition (RPD) may be used to form the transparent conductive layer 140.

Referring to fig. 4 and 5, in the present embodiment, after the step of forming the transparent conductive layer 140, the step of forming the P electrode layer 151 and the N electrode layer 152 includes:

Referring to fig. 4, a P electrode layer 151 having a work function greater than that of the transparent conductive layer 140 is formed on the transparent conductive layer 140.

As described above, the transparent conductive layer 140 is interposed between the P electrode layer 151 and the P-type gallium nitride layer 130, so that the work function difference between the P electrode layer 151 and the P-type gallium nitride layer 130 can be reduced, which is beneficial to reducing the operating voltage of the flip-chip LED chip.

In this embodiment, a metal material may be used to form the P electrode layer 151, so that the P electrode layer 151 has a certain light reflectivity while being used as an electrode, and can be used to reflect light emitted from the multiple quantum well layer 120 in the flip LED chip toward the P electrode layer 151 to the substrate 100 and transmit the light from the substrate 100 to the outside, thereby further increasing the light efficiency of the flip LED chip.

In this embodiment, the P electrode layer 151 may be formed on the surface and the sidewall of the transparent conductive layer 140, that is, the transparent conductive layer 140 is completely covered, which is favorable for receiving and reflecting the light emitted from the mqw layer 120 toward the P electrode layer 151 relatively comprehensively.

Specifically, the P electrode layer 151 may be formed in a single layer or a stacked layer structure.

In this embodiment, a P-electrode layer 151 having a stacked structure is formed, and a silver layer and a tungsten titanium layer are sequentially formed on the transparent conductive layer 140, and the silver layer and the tungsten titanium layer together constitute the P-electrode layer 151 having the stacked structure.

Specifically, the thickness of the silver layer can be in the range of 750 to 3000 angstroms, and the thickness of the tungsten titanium can be in the range of 100 to 1000 angstroms. Within the thickness range, the P electrode layer 151 is not too thin to cause a reduction in reflectivity, and the P electrode layer 151 is not too thick to affect the volume of the whole flip LED chip. However, those skilled in the art should understand that this range of values is only an example, and the thickness of each material layer constituting the P electrode layer 151 should be adjusted according to actual conditions during actual operation.

In addition, the present invention is not limited to whether the P electrode layer 151 of the stacked structure is a silver layer and a tungsten titanium layer, but in another embodiment of the present invention, a silver layer, a tungsten titanium layer, and a platinum layer may be sequentially formed on the transparent conductive layer 140, and the silver layer, the tungsten titanium layer, and the platinum layer together constitute the P electrode layer 151 of the stacked structure. The thickness of the silver layer is within the range of 750-3000 angstroms, the thickness of the titanium tungsten is within the range of 100-1000 angstroms, and the thickness of the platinum layer can be within the range of 100-1000 angstroms. Similarly, the above thickness parameter is only an example, and the thickness of the P electrode layer 151 and the thickness of each material layer in the P electrode layer 151 of the stacked structure are not limited in any way.

Referring to fig. 5, an N electrode layer 152 is formed on the N-type gallium nitride layer 110 in the opening 131.

The N electrode layer 152 in this embodiment may have a single-layer or stacked-layer structure similar to that of the P electrode layer 151 described above, and the material of the N electrode layer 152 may be aluminum, and a work function difference between this material and the N-type gallium nitride layer 110 is small, so that it is not easy to increase a barrier height between the N electrode layer 152 and the N-type gallium nitride layer 110 due to a large work function difference between the N electrode layer 152 and the N-type gallium nitride layer 110, which may further increase an operating voltage of the formed flip LED chip.

However, the material of the N electrode layer 152 may be the same as the material of the P electrode layer 151, and the present invention is not limited thereto.

in the present embodiment, the N electrode 152 should not contact the sidewall of the opening 131, that is, there is a distance 1521 between the N electrode 152 in the opening 131 and the sidewall of the opening 131. This has the advantage that the formed flip LED chip can be further prevented from leaking electricity to some extent.

the P electrode layer 151 and the N electrode layer 152 are not in contact with each other, so that a short circuit between the P electrode layer 151 and the N electrode layer 152 is prevented.

It should be noted that, the steps of forming the P electrode layer 151 and the N electrode layer 152 are not sequentially performed, or the P electrode layer 151 and the N electrode layer 152 may be formed simultaneously in the same step.

Referring to fig. 6, in the present embodiment, after the step of forming the P electrode layer 151 and the N electrode layer 152, the method further includes the following steps:

a conductive protection layer 160 is formed on the P electrode layer 151. The conductive protection layer 160 is used for protecting the formed P electrode layer 151, so that the P electrode is not easily affected by subsequent process steps, and further, the P electrode layer 151 is ensured to be flat and smooth, and further, the light reflectivity of the P electrode is favorably not affected as much as possible.

Specifically, the conductive protection layer 160 in this embodiment is formed on the surface and the sidewall of the P electrode layer 151, that is, the P electrode layer 151 is fully covered, which is favorable for protecting the P electrode layer 151 more comprehensively.

In the present embodiment, the conductive protection layer 160 has a stacked structure, and specifically, the material of the conductive protection layer 160 of the stacked structure may be one or a combination of chromium, platinum, titanium, gold, and nickel.

For example, a chromium layer, a platinum layer, a titanium layer, a gold layer, and a nickel layer may be sequentially formed to form the conductive protection layer 160, wherein the platinum layer and the titanium layer have relatively stable chemical properties and mainly play a role in protecting the P electrode layer 151; the chrome layer mainly plays a role of adhesion, that is, serves to increase adhesion between the P electrode layer 151 and the conductive protection layer 160; the gold and nickel layers serve to protect the other material layers in the conductive protection layer 160.

in the embodiment, the thickness of the chromium layer is within the range of 20-500 angstroms, and the thickness of the platinum layer is within the range of 200-1000 angstroms; the thickness of the titanium layer is within the range of 200-1000 angstroms; the thickness of the gold layer is in the range of 2000-5000 angstroms, and the thickness of the nickel layer is in the range of 200-2000 angstroms. The material layers are in the respective thickness parameter range, so that the material layers can be protected sufficiently and cannot be too thick to affect the volume of the flip LED chip.

in the present embodiment, when the conductive protection layer 160 of the stacked structure is formed, a nickel layer may be finally formed, that is, the nickel layer is located at the uppermost layer in the conductive protection layer 160 of the entire stacked structure. This has the advantages that the material properties of nickel are stable and are not easily corroded, and the use of nickel as the surface layer of the conductive protection layer 160 with a laminated structure is advantageous in that the conductive protection layer 160 is not easily affected in other subsequent steps.

However, the present invention is not limited to whether the conductive protection layer 160 has a multi-layer structure, and in other embodiments of the present invention, the conductive protection layer 160 may have a single-layer structure, and specifically, the conductive protection layer 160 may be made of titanium tungsten with a thickness ranging from 200 to 5000 angstroms. For the same reason, the thickness range is favorable for protecting the flip LED chip sufficiently and simultaneously preventing the thickness from being too thick to affect the volume of the flip LED chip.

in addition, in the present embodiment, the conductive protection layer 160 may be formed by magnetron sputtering deposition or chemical vapor deposition. However, the present invention is not limited to how the conductive protection layer 160 is formed.

Referring to fig. 7, after the step of forming the conductive protection layer 160, the method includes the following steps:

Covering an insulating reflective layer 170 on the P-type gallium nitride layer 130, the P electrode layer 151, the N-type gallium nitride 110 and the N electrode layer 152; since the conductive protection layer 160 is formed on the P electrode layer 151, the insulating reflective layer 170 is also formed on the conductive protection layer 160.

In the subsequent steps, a P electrode structure and an N electrode structure are formed in the insulating reflective layer 170, so that the insulating reflective layer 170 serves to electrically isolate the P electrode structure from the N electrode structure. In addition, since the insulating reflective layer 170 is located above the mqw layer 120, that is, when the flip-chip LED chip of the present invention operates, light emitted from the mqw layer 120 in a direction away from the substrate 100 is reflected by the insulating reflective layer 170, and then is transmitted from the substrate 100 to the outside. This is advantageous for increasing the light transmittance of the flip LED chip of the present invention.

in the present embodiment, the insulating reflective layer 170 may be formed to have a thickness ranging from 1 to 5 μm. An insulating reflective layer within this range is substantially sufficient to reflect light to the substrate 100 without being too thick to affect the overall structure of the resulting flip-chip LED chip.

In this embodiment, the insulating reflective layer 170 is a DBR (Distributed Bragg Reflection) reflective layer. The DBR reflecting layer is also called as a distributed Bragg reflector, and is a periodic structure formed by alternately arranging two materials with different refractive indexes, and light rays are totally reflected by the two materials with different refractive indexes.

Specifically, please refer to fig. 8, which is a schematic structural diagram of the DBR reflective layer in this embodiment. The step of forming the DBR reflective layer includes:

Form a plurality of bilayer structures 111 on P type gallium nitride layer, P electrode layer, N type gallium nitride and the N electrode layer in proper order, bilayer structure 111 is including the first reflector layer 11 and the second reflector layer 12 that form in proper order (that is to say, first reflector layer 11 is formed on P type gallium nitride layer 130, P electrode layer 151, N type gallium nitride 110 and N electrode layer 152, second reflector layer 12 is formed on first reflector layer 11), the refracting index of second reflector layer 12 is less than the refracting index of first reflector layer 11. The DBR reflective layer makes the light entering the DBR reflective layer more easily totally reflected by the refractive index difference between the first reflective layer 11 and the second reflective layer 12, thereby achieving the effect of increasing the overall reflectivity.

In this embodiment, 5 to 30 layers of the double-layer structure 111 may be sequentially formed, for example, 14 to 16 layers of the double-layer structure 111 may be sequentially formed, thereby forming the DBR reflective layer. The DBR reflective layer within this parameter range has a sufficient number of bi-layer structures 111 to substantially reflect light entering the DBR reflective layer without being too thick to affect the volume or waste material.

In this embodiment, the first reflective layer is made of titanium oxide with a high refractive index, and the second reflective layer is made of silicon dioxide with a relatively low refractive index. Meanwhile, the two materials have good insulating property.

in this embodiment, the insulating reflective layer may be formed by reactive plasma deposition, that is, the first reflective layer, the second reflective layer, the first reflective layer, and the second reflective layer … (and so on) are sequentially formed by reactive plasma deposition. This deposition pattern is relatively easy to control.

however, the above is only one example of the present invention, and in other embodiments of the present invention, an ODR (Omni Directional Reflector) reflective layer may also be formed as the insulating reflective layer 170. Specifically, the ODR reflective layer includes a plurality of double-layer structures, and like the DBR reflective layer described above, the double-layer structure of the ODR reflective layer also includes a first reflective layer and a second reflective layer formed in this order, where the refractive index of the second reflective layer is lower than that of the first reflective layer. In addition, forming the ODR reflective layer further includes:

after a plurality of double-layer structures of the ODR reflecting layer are formed, a metal reflecting layer is formed on the surfaces of the plurality of double-layer structures and used for reflecting light rays penetrating through the double-layer structures in the ODR reflecting layer.

The number of the double-layer structures in the ODR reflective layer may be the same as the number of the double-layer structures in the DBR reflective layer described above (5 to 30 double-layer structures in this embodiment). However, since the double-layer structure of the ODR reflective layer has a metal reflective layer, the number of double-layer structures in the ODR reflective layer may be slightly less than that in the DBR reflective layer described above. For example, the number of the double-layer structure in the ODR reflective layer may be about 5 to 8.

in addition, the first and second reflective layers of the ODR reflective layer may be made of the same material as the first and second reflective layers 11 and 12 of the DBR reflective layer, that is, the first reflective layer may be made of titanium oxide having a relatively high refractive index, and the second reflective layer may be made of silicon dioxide having a relatively low refractive index.

Meanwhile, the formation method of the DBR reflective layer can be the same as the formation method of the DBR reflective layer, that is, the formation method of the DBR reflective layer is formed by using the reactive plasma deposition method.

with reference to fig. 7, after the insulating reflective layer 170 is formed, a P electrode structure electrically connected to the P electrode layer 151 and an N electrode structure electrically connected to the N electrode layer 152 are formed in the insulating reflective layer 170. Specifically, the present embodiment includes the following steps:

The insulating reflective layer 170 is etched to form a first opening 171 exposing a portion of the P electrode layer 151 and a second opening 172 exposing the N electrode layer 152. That is, the first opening 171 corresponds to the P electrode layer 151, the second opening 172 corresponds to the N electrode layer 152 in the opening 131, and metal wires are formed in the first opening 171 and the second opening 172 in the subsequent steps to respectively lead out the P electrode and the N electrode of the flip LED chip of the present invention.

Since the conductive protection layer 160 is formed on the P electrode layer 151 in this embodiment, the first opening 171 in this embodiment specifically exposes the conductive protection layer 160. As mentioned above, the conductive protection layer 160 has conductivity, and thus, the implementation of the present invention is not affected.

In this embodiment, a BOE etching process (buffer oxide etch) may be used to etch the insulating reflective layer 170 to form the first opening 171 and the second opening 172. As mentioned above, since the surface of the partial conductive protection layer 160 is a nickel layer, the conductive protection layer 160 is not easily affected by the BOE etching in this step when the first opening 171 is formed.

please refer to fig. 9 and fig. 10 in combination, wherein fig. 10 is a top view of the structure shown in fig. 9. Filling a metal layer 180 on the insulating reflective layer 170 and in the first opening 171 and the second opening 172, wherein a first conductive pillar 181 electrically connected to the P electrode layer 151 is formed in a portion of the metal layer 180 located in the first opening 171, and the first conductive pillar 181 constitutes the P electrode structure; the part of the metal layer 180 located in the second opening 182 forms a second conductive pillar 182 electrically connected to the N electrode layer 152; the second conductive pillar 182 constitutes the N-electrode structure.

in addition, in the present embodiment, a conductive line pattern is further formed on the surface of the insulating reflective layer 170 to lead out the first conductive pillar 181 and the second conductive pillar 182, and further to lead out the P electrode layer 151 and the N electrode layer. Referring to fig. 10, a portion of the metal layer 180 on the surface of the insulating reflective layer 170 forms the conductive line pattern, which includes a first pattern 183 and a second pattern 184 that are not in contact with each other, wherein the first pattern 183 corresponds to the first conductive pillar 181, and is used for leading out the P electrode through the first conductive pillar 181; similarly, the second pattern 184 corresponds to the second conductive pillar 182, and is used for leading out the N electrode through the second conductive pillar 182.

However, the pattern of the metal layer 180 in fig. 10 is only an example, and the present invention does not limit the pattern of the metal layer 180.

In this embodiment, the metal layer 180 of one or a combination of chromium, aluminum, titanium, platinum, gold, and nickel may be formed. Wherein the thickness of chromium is within the range of 20-50 angstroms, the thickness of aluminum is within the range of 750-3000 angstroms, the thickness of titanium is within the range of 200-1000 angstroms, and the thickness of platinum is within the range of 200-1000 angstroms; the thickness of the gold is in the range of 2000-5000 angstroms; the thickness of the nickel is in the range of 200-1000 angstroms.

In this embodiment, for example, the second conductive pillar 182 is formed, and in this embodiment, chromium, aluminum, titanium, platinum, gold, and nickel may be sequentially formed in the second opening 172 to form the second conductive pillar 182. The chromium layer is used as an adhesion layer for increasing the adhesion between the second conductive pillar and the N electrode layer 152, and simultaneously, the size of ohmic contact between the second conductive pillar and the N electrode layer 152 can be reduced; the aluminum layer has good light reflectivity, which is beneficial to further reflecting the light emitted by the multiple quantum well layer 120 to the substrate 100; the titanium and platinum layers are used for preventing the aluminum material from diffusing, and the structure of the titanium, the platinum, the titanium and the platinum is beneficial to relieving the stress of the material; the gold layer is beneficial to increase the conductivity of the second conductive pillar 182; the nickel layer is located on the surface layer of the second conductive pillars 182, and as described above, the material property of the nickel itself is stable, so that the entire second conductive pillars 182 are not easily affected by other subsequent processes.

thereafter, referring to fig. 11 to 13, after the P electrode structure and the N electrode structure are formed, the method further includes the following steps:

Referring first to fig. 11, a passivation layer 190 is formed on the insulating reflective layer 170 and the metal layer 180, and the passivation layer 190 serves to insulate and isolate the pattern of the metal layer 180 on the surface of the insulating reflective layer 170.

In this embodiment, the passivation layer 190 may be SiO₂SiN or SiON as material.

In the present embodiment, the passivation layer 190 may be formed to have a thickness ranging from 5000 to 20000 angstroms, but the above thickness range is only an embodiment and the present invention is not limited thereto.

thereafter, referring to fig. 12, the passivation layer 190 is etched to expose the first conductive pillar 181 and the second conductive pillar 182, so as to lead out the P electrode layer 151 and the N electrode layer 152 connected to the first conductive pillar 181 and the second conductive pillar 182, respectively.

Referring to fig. 13, the extraction electrodes 210 and 220 corresponding to the first conductive pillar 181 and the second conductive pillar 182 are formed, and since the first conductive pillar 181 is electrically connected to the P electrode layer 151, the extraction electrode 210 is used for extracting the P electrode layer 151 so as to facilitate subsequent steps such as packaging; similarly, the second conductive pillar 182 is electrically connected to the N electrode layer 152, and thus serves as the extraction electrode 220 for extracting the N electrode layer 152.

The extraction electrodes 210, 220 should have a distance therebetween to prevent short circuit, and in this embodiment, the distance d should be not less than 100 μm.

in the present embodiment, one or more of chromium, aluminum, titanium, platinum, gold, or tin may be used as the material of the extraction electrodes 210, 220.

Specifically, in the embodiment, the thickness of chromium is within a range of 20 to 50 angstroms, the thickness of aluminum is within a range of 750 to 3000 angstroms, the thickness of titanium is within a range of 200 to 1000 angstroms, and the thickness of platinum is within a range of 200 to 1000 angstroms; the thickness of the gold is in the range of 2000-5000 angstroms; the thickness of the tin is in the range of 200 to 1000 angstroms.

In addition, referring to fig. 13, the present invention further provides a flip LED chip, including:

A substrate 100; in the present embodiment, the material of the substrate 100 is sapphire (Al)₂O₃). However, the material of the substrate 100 is not limited in the present invention, and the material may be, for example, spinel (MgAl)₂O₄) SiC, ZnS, ZnO, GaAs, or the like.

An N-type gallium nitride layer 110 formed on the front surface of the substrate;

A multiple quantum well layer 120 formed on the N-type gallium nitride layer 110;

and a P-type gallium nitride layer 130 formed on the MQW layer 120.

In the present embodiment, the P-type gallium nitride layer 130 may be formed of Mg-doped In-GaN, Mg-doped P-GaN, and Mg-doped Al-GaN sequentially formed on the multiple quantum well layer 120, the multiple quantum well layer 120 may be a quantum well structure formed by alternately stacking InGaN layers and GaN layers, and the N-type gallium nitride layer 110 may be formed of a Si-doped GaN layer.

An opening 131 (please refer to fig. 3 in combination) is formed in the P-type gallium nitride layer 130 and the multi-quantum well layer 120 to expose the N-type gallium nitride layer 110; the N-electrode layer of the present invention is formed on the N-type gallium nitride layer 110 in the opening.

in this embodiment, a transparent conductive layer 140 is formed between the P-type gallium nitride layer 130 and the P-electrode layer 151, and a work function of the transparent conductive layer 140 is smaller than a work function of the P-electrode layer 151 when meeting the work function of the P-type gallium nitride layer 130. That is to say, the work function of the transparent conductive layer 140 is between the P-type gallium nitride layer 130 and the P-electrode layer 151, which is favorable for reducing the barrier height between the P-type gallium nitride layer 130 and the P-electrode layer 151, and further favorable for reducing the ohmic contact between the P-type gallium nitride layer 130 and the P-electrode, and this can improve the working performance of the flip-chip LED chip, for example, reduce the working voltage of the flip-chip LED chip.

The transparent conductive layer 140 is conductive, and therefore does not affect the electrical connection between the P electrode layer 151 and the P-type gallium nitride layer 130.

in this embodiment, the material of the transparent conductive layer 140 may be Indium Tin Oxide (ITO), and the transparent conductive layer 140 made of this material has high light transmittance, that is, has high transmittance in a visible light band, so that light emitted from the quantum well is not substantially blocked, and light loss is reduced.

In addition, the work function of the ito is generally between the work function of the P-type gan layer 130 and the work function of the P-electrode layer 151 formed subsequently, so that the above purpose of reducing the barrier height between the P-type gan layer 130 and the P-electrode layer 151 can be achieved.

It should be noted that, those skilled in the art should understand that the specific work function of the transparent conductive layer 140 can be adjusted by adjusting the process parameters during the formation thereof, and the present invention aims to make the work function of the formed transparent conductive layer 140 between the P-type gallium nitride layer 130 and the P-electrode layer 151 formed subsequently, so the specific work function thereof should be adjusted according to the actual situation, which is not limited by the present invention.

in addition, the transparent conductive layer 140 made of the indium tin oxide material generally has a relatively small resistance, so that the current of the P electrode layer 151 is spread on the transparent conductive layer 140 when the flip LED chip works, which is beneficial to achieving the purpose of current expansion, further preventing the occurrence of current congestion, increasing the quantum efficiency, and further being beneficial to improving the working performance of the flip LED chip.

However, the invention is not limited to whether the material of the transparent conductive layer 140 is indium tin oxide, and in other embodiments of the invention, the transparent conductive layer 140 may also be other transparent and conductive materials, such as zinc oxide. The zinc oxide and the indium tin oxide have similar work functions, and are also favorable for reducing the barrier height between the P-type gallium nitride layer 130 and the subsequently formed P electrode layer 151, so that the working performance of the flip LED chip is improved, and the working voltage of the flip LED chip is reduced.

In this embodiment, the thickness of the transparent conductive layer 140 is within a range of 50 to 3000 angstroms. The transparent conductive layer 140 within this thickness range is not too thin to reduce the conductive capability (i.e. to increase the resistance), and is not too thick to absorb too much light to reduce the transmittance.

The flip LED chip of the present invention further comprises a P electrode layer 151 formed on the P-type gallium nitride layer 130 and an N electrode layer 152 formed on the N-type gallium nitride layer in the opening; as described above, since the transparent conductive layer 140 is interposed between the P electrode layer 151 and the P-type gallium nitride layer 130, the work function difference between the P electrode layer 151 and the P-type gallium nitride layer 130 can be reduced, which is beneficial to reducing the operating voltage of the flip-chip LED chip.

In this embodiment, the P electrode layer 151 is made of a metal material, so that the P electrode layer 151 has a certain light reflectivity while serving as an electrode, and can be used for reflecting light emitted from the multiple quantum well layer 120 in the flip LED chip towards the P electrode layer 151 to the substrate 100, thereby being beneficial to increasing the light efficiency of the flip LED chip.

In this embodiment, the P electrode layer 151 is formed on the surface and the sidewall of the transparent conductive layer 140, that is, the P electrode covers the transparent conductive layer 140 completely, which is favorable for receiving and reflecting the light emitted from the mqw layer 120 toward the P electrode layer 151 more comprehensively.

Specifically, the P electrode layer 151 may have a single layer structure or a stacked layer structure.

in the embodiment, the P electrode layer 151 is a laminated structure, for example, a silver layer is formed on the transparent conductive layer 140, a tungsten layer is formed on the silver layer, and the silver layer and the tungsten titanium layer together constitute the P electrode layer 151 of the laminated structure.

Specifically, the thickness of the silver layer is within the range of 750-3000 angstroms, and the thickness of the tungsten titanium is within the range of 100-1000 angstroms. Within the thickness range, the P electrode layer 151 is not too thin to cause a reduction in reflectivity, and the P electrode layer 151 is not too thick to affect the volume of the whole flip LED chip. However, those skilled in the art should understand that this range of values is only an example, and the thickness of each material layer constituting the P electrode layer 151 should be adjusted according to actual conditions during actual operation.

In addition, the invention is not limited to whether the P electrode layer 151 of the stacked structure is necessarily a silver layer and a tungsten titanium layer, and other embodiments of the invention may further include the following structures:

A silver layer on the transparent conductive layer 140, a tungsten titanium layer on the silver layer, and a platinum layer on the tungsten titanium layer, wherein the silver layer, the tungsten titanium layer, and the platinum layer together form a P electrode layer 151 of the stacked structure. The thickness of the silver layer is within the range of 750-3000 angstroms, the thickness of the titanium tungsten is within the range of 100-1000 angstroms, and the thickness of the platinum layer can be within the range of 100-1000 angstroms. Similarly, the above thickness parameter is only an example, and the thickness of the P electrode layer 151 and the thickness of each material layer in the P electrode layer 151 of the stacked structure are not limited in any way.

In addition, in this embodiment, a conductive protection layer 160 is further disposed on the P electrode layer 151. The conductive protection layer 160 is used for protecting the formed P electrode layer 151, so that the P electrode layer 151 is not easily affected by subsequent process steps, and further the smoothness and smoothness of the P electrode layer 151 are ensured, and further the influence of the light reflectivity step of the P electrode layer 151 is ensured.

For example, the conductive protection layer 160 may include a chromium layer formed on the P electrode layer 151, a platinum layer formed on the chromium layer, a titanium layer formed on the platinum layer, a gold layer formed on the titanium layer, and a nickel layer formed on the gold layer, wherein the platinum layer and the titanium layer are chemically stable and mainly play a role in protecting the P electrode layer 151 and the N electrode layer 152; the chrome layer mainly plays a role of adhesion, that is, serves to increase adhesion between the P electrode layer 151, the N electrode layer 152, and the conductive protection layer 160; the gold and nickel layers serve to protect the other material layers in the conductive protection layer 160.

in the embodiment, the thickness of the chromium layer is within the range of 20-500 angstroms, and the thickness of the platinum layer is within the range of 200-1000 angstroms; the thickness of the titanium layer is within the range of 200-1000 angstroms; the thickness of the gold layer is in the range of 2000-5000 angstroms, and the thickness of the nickel layer is in the range of 200-2000 angstroms. These materials are advantageously in their respective thickness ranges to provide adequate protection without being so thick as to interfere with the bulk of the flip-chip LED chip.

In the present embodiment, the nickel layer is located at the uppermost layer in the entire conductive protection layer 160 of the stacked structure. This has the advantages that the nickel material is stable and is not easily corroded, and the use of nickel as the surface layer of the conductive protection layer 160 with a laminated structure is beneficial to protecting the conductive protection layer 160.

However, the present invention is not limited to whether the conductive protection layer 160 has a multi-layer structure, and in other embodiments of the present invention, the conductive protection layer 160 may have a single-layer structure, and specifically, the conductive protection layer 160 may be made of titanium tungsten with a thickness ranging from 200 to 5000 angstroms. The thickness range is favorable for protecting the flip LED chip sufficiently and simultaneously preventing the flip LED chip from being too thick to affect the volume of the flip LED chip.

The flip LED chip also comprises an insulating reflecting layer covering the P-type gallium nitride layer, the P electrode layer, the N-type gallium nitride layer and the N electrode layer; since the conductive protection layer 160 is formed on the P electrode layer 151, the insulating reflective layer 170 in this embodiment is also located on the conductive protection layer 160.

since the P electrode structure and the N electrode structure are formed in the insulating reflective layer 170, the insulating reflective layer 170 serves to electrically isolate the P electrode structure from the N electrode structure. In addition, since the insulating reflective layer 170 is located above the mqw layer 120, that is, when the flip-chip LED chip of the present invention operates, light emitted from the mqw layer 120 in a direction away from the substrate 100 is reflected by the insulating reflective layer 170, and then is transmitted from the substrate 100 to the outside. This is advantageous for increasing the light transmittance of the flip LED chip of the present invention.

In this embodiment, the thickness of the insulating reflective layer 170 is in a range of 1 to 5 μm. An insulating reflective layer within this range is substantially sufficient to reflect light to the substrate 100 without being too thick to affect the overall structure of the resulting flip-chip LED chip.

Be located a plurality of bilayer structure 111 on P type gallium nitride layer, P electrode layer, N type gallium nitride and the N electrode layer, bilayer structure 111 includes first reflection stratum 11 and is located first reflection stratum 11 surface, and the refracting index is less than the second reflection stratum 12 of first reflection stratum 11 (that is to say, first reflection stratum 11 is formed on P type gallium nitride layer 130, P electrode layer 151, N type gallium nitride 110 and N electrode layer 152, second reflection stratum 12 is formed on first reflection stratum 11), the refracting index of second reflection stratum 12 is less than the refracting index of first reflection stratum 11. The DBR reflective layer makes the light entering the DBR reflective layer more easily totally reflected by the refractive index difference between the first reflective layer 11 and the second reflective layer 12, thereby achieving the effect of increasing the overall reflectivity.

only the two-layer double-layer structure 111 is shown in fig. 8. It should be understood by those skilled in the art that the present invention should not be limited to the structure shown in fig. 8.

In this embodiment, the DBR reflective layer includes 5-30 double-layer structures 111. For example, the structure includes 14 to 16 bi-layer structures 111. The DBR reflective layer within this parameter range has a sufficient number of bi-layer structures 111 to substantially reflect light entering the DBR reflective layer without being too thick to affect the volume or waste material.

in this embodiment, the material of the first reflective layer 11 is titanium oxide with a high refractive index, and the material of the second reflective layer 12 is silicon dioxide with a relatively low refractive index. Meanwhile, the two materials have good insulating property.

The ODR reflecting layer further comprises a metal reflecting layer formed on the surfaces of the plurality of double-layer structures, and the metal reflecting layer is used for reflecting light rays penetrating through the double-layer structures in the ODR reflecting layer.

The flip LED chip of the present invention further includes a P electrode structure formed in the insulating reflective layer and electrically connected to the P electrode layer 151, and an N electrode structure formed in the insulating reflective layer and electrically connected to the N electrode layer 151.

Since the conductive protection layer 160 is formed on the P electrode layer 151 in this embodiment, the P electrode structure in this embodiment is specifically formed on the conductive protection layer 160. This does not affect the practice of the invention.

In this embodiment, a metal layer 180 is further formed in the insulating reflective layer 170 and on the surface thereof, wherein a portion of the metal layer 180 located in the first opening 171 forms a first conductive pillar 181 electrically connected to the P electrode layer 151, and the first conductive pillar 181 constitutes the P electrode structure; the part of the metal layer 180 located in the second opening 182 forms a second conductive pillar 182 electrically connected to the N electrode layer 152; the second conductive pillar 182 constitutes the N-electrode structure.

In addition, in the present embodiment, a conductive wire pattern is formed on the surface of the insulating reflective layer 170 to respectively lead out the first conductive pillar 181 and the second conductive pillar 182, and further lead out the P electrode layer 151 and the N electrode layer (see fig. 10). The part of the metal layer 180 on the surface of the insulating reflective layer 170 forms the conductive line pattern, which includes a first pattern 183 and a second pattern 184 that are not in contact with each other, wherein the first pattern 183 corresponds to the first conductive pillar 181, and is used for leading out the P electrode through the first conductive pillar 181; similarly, the second pattern 184 corresponds to the second conductive pillar 182, and is used for leading out the N electrode through the second conductive pillar 182.

In this embodiment, the material of the metal layer 180 may be one or more of chromium, aluminum, titanium, platinum, gold, and nickel. Wherein the thickness of chromium is within the range of 20-50 angstroms, the thickness of aluminum is within the range of 750-3000 angstroms, the thickness of titanium is within the range of 200-1000 angstroms, and the thickness of platinum is within the range of 200-1000 angstroms; the thickness of the gold is in the range of 2000-5000 angstroms; the thickness of the nickel is in the range of 200-1000 angstroms.

in this embodiment, taking the second conductive pillars 182 as an example, in this embodiment, the second conductive pillars 182 are a chromium layer-aluminum layer-titanium layer-platinum layer-gold layer-nickel layer structure formed on the N electrode layer 152. The chromium layer is used as an adhesion layer for increasing the adhesion between the second conductive pillar and the N electrode layer 152, and simultaneously, the size of ohmic contact between the second conductive pillar and the N electrode layer 152 can be reduced; the aluminum layer has good light reflectivity, which is beneficial to further reflecting the light emitted by the multiple quantum well layer 120 to the substrate 100; the titanium and platinum layers are used for preventing the aluminum material from diffusing, and the structure of the titanium, the platinum, the titanium and the platinum is beneficial to relieving the stress of the material; the gold layer is beneficial to increase the conductivity of the second conductive pillar 182; the nickel layer is located on the surface layer of the second conductive pillars 182, and as described above, the material property of the nickel itself is stable, so that the entire second conductive pillars 182 are not easily affected by other subsequent processes.

In this embodiment, a passivation layer 190 is further formed on the metal layer 180, and the passivation layer 190 is used to isolate the metal layer patterns on the surface 170 from each other.

In the embodiment, the thickness of the passivation layer 190 is in the range of 5000 to 20000 angstroms, but the above thickness range is only an example, and the invention is not limited thereto.

the passivation layer 190 has a pattern to expose the first conductive pillars 181 and the second conductive pillars 182.

in this embodiment, the passivation layer 190 has the extraction electrodes 210 and 220 formed thereon and corresponding to the first conductive pillar 181 and the second conductive pillar 182, and since the first conductive pillar 181 is electrically connected to the P electrode layer 151, the extraction electrode 210 is used for extracting the P electrode layer 151 for subsequent packaging and other steps; similarly, the second conductive pillar 182 is electrically connected to the N electrode layer 152, and thus serves as the extraction electrode 220 for extracting the N electrode layer 152.

In this embodiment, the material of the extraction electrodes 210 and 220 may be one or more of chromium, aluminum, titanium, platinum, gold, or tin. Specifically, the thickness of chromium is within the range of 20-50 angstroms, the thickness of aluminum is within the range of 750-3000 angstroms, the thickness of titanium is within the range of 200-1000 angstroms, and the thickness of platinum is within the range of 200-1000 angstroms; the thickness of the gold is in the range of 2000-5000 angstroms; the thickness of the tin is in the range of 200 to 1000 angstroms.

In addition, the flip LED chip of the present invention can be obtained by, but is not limited to, the above-described formation method.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for forming a flip LED chip, comprising:

Providing a substrate;

Forming a P electrode layer with a work function larger than that of the transparent conductive layer on the transparent conductive layer, wherein the P electrode layer is made of the following materials: the P electrode layer is formed on the surface and the side wall of the transparent conducting layer;

forming an N electrode layer on the N-type semiconductor layer in the opening, wherein the P electrode layer is positioned on two sides of the N electrode layer;

Forming a P electrode structure electrically connected with the P electrode layer and an N electrode structure electrically connected with the N electrode layer in the insulating reflecting layer;

Forming a passivation layer on the insulating reflective layer, the P electrode structure and the N electrode structure;

Etching the passivation layer to expose the P electrode structure and the N electrode structure;

and forming a P extraction electrode and an N extraction electrode which respectively correspond to the P electrode structure and the N electrode structure on the passivation layer, wherein a space is reserved between the P extraction electrode and the N extraction electrode.

2. The method according to claim 1, wherein a material of the transparent conductive layer is indium tin oxide or zinc oxide.

3. The method of forming as claimed in claim 1, wherein after the step of forming the P electrode layer and before the step of covering the insulating reflective layer, the method of forming further comprises:

4. The method of forming as claimed in claim 1, wherein the step of covering the insulating reflective layer comprises:

covering the DBR reflective layer or the ODR reflective layer.

5. The method of forming as claimed in claim 1, wherein the step of covering the insulating reflective layer comprises: forming an insulating reflective layer with a thickness of 1-5 μm.

6. The forming method of claim 4, wherein the step of covering the insulating reflective layer comprises: form a plurality of bilayer structures in proper order, bilayer structure is including the first reflection stratum and the second reflection stratum that form in proper order, the refracting index of second reflection stratum is less than the refracting index of first reflection stratum.

7. The forming method of claim 6, wherein the step of covering the insulating reflective layer comprises: and sequentially forming 5-30 layers of double-layer structures to form the DBR reflecting layer or the ODR reflecting layer.

8. The method of forming as claimed in claim 7, wherein the step of covering the insulating reflective layer comprises: sequentially forming 14-16 layers of double-layer structures to form the DBR reflecting layer;

9. The method according to claim 6, wherein a material of the first reflective layer is titanium oxide, and a material of the second reflective layer is silicon dioxide.

10. The method of claim 1, wherein the insulating reflective layer is formed by reactive plasma deposition.

11. the method of forming as claimed in claim 1, wherein the step of forming the P electrode structure and the N electrode structure in the insulating reflective layer comprises:

12. The forming method of claim 11, wherein the step of forming the second conductive pillar comprises:

13. A flip LED chip, comprising:

A substrate;

An N-type semiconductor layer formed on the substrate;

an active layer formed on the N-type semiconductor layer;

A P electrode layer is arranged on the P type semiconductor layer, and an N electrode layer is arranged on the N type semiconductor layer in the opening, wherein the P electrode layer is positioned on two sides of the N electrode layer;

An N electrode structure formed in the insulating reflective layer and electrically connected to the N electrode layer;

A passivation layer formed on the insulating reflective layer, the passivation layer exposing the P electrode structure and the N electrode structure;

The P leading-out electrode and the N leading-out electrode are formed on the passivation layer and respectively correspond to the P electrode structure and the N electrode structure, and a space is reserved between the P leading-out electrode and the N leading-out electrode;

A transparent conducting layer is formed between the P-type semiconductor layer and the P-electrode layer, the work function of the transparent conducting layer is greater than that of the P-type semiconductor layer and less than that of the P-electrode layer, and the P-electrode layer is made of: and the P electrode layer is formed on the surface and the side wall of the transparent conducting layer.

14. The flip LED chip of claim 13, wherein the material of the transparent conductive layer is indium tin oxide or zinc oxide.

15. The flip LED chip of claim 13, wherein a conductive protective layer is formed between said P electrode layer and said insulating reflective layer.

16. the flip LED chip of claim 13, wherein the insulating reflective layer is a DBR reflective layer or an ODR reflective layer.

17. the flip LED chip of claim 16, wherein the insulating reflective layer comprises a plurality of double layer structures, the double layer structures comprising a first reflective layer and a second reflective layer on a surface of the first reflective layer, the second reflective layer having a refractive index lower than a refractive index of the first reflective layer.

18. The flip LED chip of claim 17, wherein the material of the first reflective layer is titanium oxide and the material of the second reflective layer is silicon dioxide.