CN110649130B - Ultraviolet light-emitting diode and preparation method thereof - Google Patents
Ultraviolet light-emitting diode and preparation method thereof Download PDFInfo
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- CN110649130B CN110649130B CN201910858779.3A CN201910858779A CN110649130B CN 110649130 B CN110649130 B CN 110649130B CN 201910858779 A CN201910858779 A CN 201910858779A CN 110649130 B CN110649130 B CN 110649130B
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/10—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/04—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
- H01L33/06—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
- H01L33/38—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape
- H01L33/382—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape the electrode extending partially in or entirely through the semiconductor body
Abstract
The patent discloses an ultraviolet light emitting diode, it includes: an epitaxial structure; the micropore structure layer is arranged on the P-type semiconductor material side of the epitaxial structure and comprises a micropore area and an electrode matching area; hollow holes are formed in the micropore areas; the electrode matching area is matched with the shape of the negative electrode of the ultraviolet light-emitting diode chip, and is a solid area; and the P-type ohmic contact layer is a metal material layer, and one side of the P-type ohmic contact layer is formed on the microporous structure layer. The omnibearing reflecting mirror is composed of a P-type semiconductor material layer, a thin microporous structure layer and a P-type ohmic contact layer through the scheme. Light emitted by the light-emitting layer is emitted from the N electrode through the reflection of the ODR, and the total reflection and the Fresnel scattering of the micropore structure and the air interface are utilized, so that the absorption of metal of a metal reflector to purple light in the prior art is reduced to the maximum extent, and the light extraction efficiency is improved.
Description
Technical Field
The patent belongs to the technical field of semiconductors, and particularly relates to an ultraviolet light-emitting diode and a preparation method thereof.
Background
In the prior art, the epitaxial structure of the uv led with a vertical structure is shown in fig. 1, and comprises a substrate 100, a nucleation layer, an undoped aluminum nitride layer 101, an n-type aluminum gallium nitride layer 102, an active layer 103, an electron blocking layer 104 and a P-type hole conducting layer 105, wherein a reflective layer, a P, N electrode, an electrode transfer and the like are sequentially formed on the epitaxial structure during the chip fabrication.
In order to improve the light extraction efficiency of the LED, one method is to provide a bragg reflector DBR which is a periodic structure composed of materials having different refractive indexes alternately arranged in an ABAB manner, and the optical thickness of each layer of material is 1/4 of the central emission wavelength, thus forming a reflector having multiple layers and having a reflectance of up to 99% or more. Although the DBR mirror has high reflection efficiency, it has a disadvantage in that the manufacturing process is complicated, the cost is high, and a multi-layer structure is necessary. Another solution that occurs in the prior art is to provide a metal reflective layer 200, as shown in fig. 2, in which light is totally reflected during reflection by the multilayer material of the chip.
In addition, the ultraviolet light emitting diode in the prior art adopts a vertical structure primary electrode and a single roughening process, so that electrode stripping (Peeling) is caused to a great extent.
Disclosure of Invention
The present patent is based on the above-mentioned needs of the prior art, and the technical problem to be solved by the present patent is to provide a novel vertical structure ultraviolet semiconductor light emitting diode and a preparation method thereof, wherein the semiconductor light emitting diode has an ODR reflector structure with a thinned structure and two matched electrodes.
In order to solve the technical problem, the technical scheme that this patent provided includes:
an ultraviolet light emitting diode, comprising: the epitaxial structure of the ultraviolet light-emitting diode comprises an N-type semiconductor material layer, a quantum well and a P-type semiconductor material layer; the micropore structure layer is arranged on the P-type semiconductor material side of the epitaxial structure and comprises a micropore area and an electrode matching area; hollow holes are formed in the micropore areas; the electrode matching area is matched with the shape of the negative electrode of the ultraviolet light-emitting diode chip, and is a solid area; the P-type ohmic contact layer is a metal material layer, and one side of the P-type ohmic contact layer is formed on the micropore structure layer; the bonding layer is arranged on the opposite side of the contact side of the P-type ohmic contact layer and the microporous structure layer, and is made of metal; and the bonding substrate is arranged on the opposite side of the contact side of the bonding layer and the P-type ohmic contact layer.
And a preparation method of the ultraviolet light-emitting diode chip is characterized by comprising the following steps: step one, preparing an ultraviolet light-emitting diode epitaxial structure; sequentially forming an epitaxial structure of an ultraviolet light-emitting semiconductor on a substrate; preparing a thinned micropore structure, and depositing a layer of SiO2 with the thickness of 250nm; a mask array of thin micropores is manufactured by using SiO2 through a photoetching technology, and no micropores exist at the corresponding N electrode part; step three, evaporating a NiAu layer; evaporating and plating a bonding layer Au; step five, manufacturing a bonding substrate; step six, manufacturing a primary electrode; firstly, soaking with primary roughening liquid comprising hydrogen peroxide, citric acid and water to prepare an N-type ohmic contact layer; manufacturing an ohmic contact electrode Al/Cr; forming N-face ohmic contact; and step seven, manufacturing a secondary electrode, namely coarsening N-plane AlGaN in other areas except for the primary electrode area by using KOH solution, and forming the secondary electrode on the primary electrode.
The Omni-directional reflector (Omni-Directional Reflector, ODR) is formed by a thin microporous structure layer, a P-type ohmic contact layer and a bonding layer through the scheme. Light emitted by the light-emitting layer is emitted from the N electrode through the reflection of the ODR, and the total reflection and the Fresnel scattering of the micropore structure and the air interface are utilized, so that the absorption of metal of a metal reflector to purple light in the prior art is reduced to the maximum extent, and the light extraction efficiency is improved.
Drawings
These and/or other aspects will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is an epitaxial structure diagram of a prior art vertical structure UV LED;
FIG. 2 is an epitaxial structure diagram of another UV LED of vertical structure in the prior art;
FIG. 3 is a diagram of the overall structure of a thinned microporous structure vertical UV chip;
FIG. 4 is a schematic view of a thinned microporous structure;
fig. 5 is a plan view of an N-electrode and a thinned microporous structure.
Detailed Description
The technical solutions described in this patent include various specific embodiments and modifications made on the various specific embodiments. In the present embodiment, these technical solutions are exemplarily set forth by way of accompanying drawings so that the inventive concept, technical features, effects of technical features, etc. of the present patent will become more apparent from the description of the present embodiment. It should be noted that the scope of protection of the present patent should obviously not be limited to what has been described in these embodiments, but can be implemented in various ways under the inventive concept of the present patent.
In the description of this embodiment, attention is directed to the following reading references in order to enable an accurate understanding of the meaning expressed by the text in this embodiment:
first, in the drawings of this patent, the same or corresponding elements/layers and the like will be denoted by the same reference numerals. Therefore, the explanation may not be repeated later on for the names of the reference numerals or the elements/layers etc. which have been previously appeared. Also, in the present embodiment, if the terms "first", "second", etc. are used to modify various elements or elements, the terms "first", "second", etc. do not denote a sequence, but rather merely distinguish one element or element from another. Furthermore, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" refer not only to the singular but also to the plural.
Still further, inclusion or inclusion, should be understood that an open ended description does not exclude the presence of other elements than those already described; also, when a layer, region or element is referred to as being "formed on," "disposed on" another layer, region or element, it can be directly or indirectly formed on the other layer, region or element, and similarly, when the relationship between two elements is expressed using terms such as connection, the like, it can be directly or indirectly connected without particular limitation. The term "and/or" may refer to a relationship between two elements that are connected, either together or together.
In addition, in order to illustrate the technical solution of the present patent, the dimensions of the elements depicted in the drawings of the present patent do not represent the dimensional proportion relation of the actual elements, and in particular, in the case of the relatively microscopic structure of the present patent, the dimensions, thickness, proportion, etc. are enlarged or reduced for convenience of expression.
Example 1
The embodiment provides an ultraviolet light emitting diode.
With the development of LED technology, the kinds of LED light sources are variously changed for different needs. For example, uv leds are emerging in the art to meet various demands for uv environments.
Ultraviolet light emitting diodes generally refer to LEDs having a light emission center wavelength of 400nm or less, but sometimes the light emission center wavelength is more than 380nm and the light emission center wavelength is less than 300nm are referred to as near ultraviolet LEDs, but they are all within the category of ultraviolet light emitting diodes referred to in this embodiment.
In the prior art, an ultraviolet light emitting diode generally includes an epitaxial structure, a reflective structure, an electrode and the like. The epitaxial structure is used for forming various layers on the substrate to complete the luminous function of the ultraviolet light-emitting diode, the reflecting structure is used for reflecting light rays in one or more areas to enable the light rays to emit along the expected direction, and the electrode structure is used for supplying power to the ultraviolet light-emitting diode chip. In the prior art, the ultraviolet light is greatly affected by absorption of each layer, so that a very important aspect of improving the brightness of the ultraviolet light emitting diode is to reduce the loss of each layer in the ultraviolet light emitting diode to the ultraviolet light. This is also a problem to be solved in one of the first embodiments.
For this purpose, this embodiment is illustrated with respect to the structure of fig. 3. The materials and structures of the layers of the present embodiment can of course be changed by those skilled in the art according to the inventive concept of the present embodiment; however, while specific advantages of the materials and structures employed are described in this example, it is sufficient to demonstrate that the materials and structures are further inventive relative to conventional options in the art. That is, in the description of the specific example, if technical means and technical effects of an element such as a specific component/module are described, the element should be regarded as further improvements to the technical solution within the framework of the present general inventive concept in the example, and should not be construed as common general knowledge in conventional material selection, parameter selection, structural design, and the like.
The ultraviolet light emitting diode as shown in fig. 3 includes:
epitaxial structure of ultraviolet light-emitting diode
The epitaxial structure of the ultraviolet light emitting diode mainly plays a role in forming PN junction and generating ultraviolet light. The epitaxial structure of an ultraviolet light emitting diode such as in fig. 3 includes: an N-type semiconductor material layer 1, a quantum well layer 2 and a P-type semiconductor material layer 3.
The N-type semiconductor material layer 1 preferably adopts N-type AlGaN; the P-type semiconductor material layer 3 is preferably P-type GaN, and according to the prior studies, the PN junction formed by the N-AlGaN and P-GaN materials is a semiconductor material layer of a preferred ultraviolet light emitting diode, and of course, other materials may be included in the light emitting diode in addition to the above materials to optimize various performances of the light emitting diode, which can be realized by those skilled in the art.
A quantum well 2, a quantum well layer is formed under the N-type semiconductor material layer. Quantum wells refer to potential wells in which electrons or holes having a quantum confinement effect are formed by the interval arrangement of 2 different semiconductor materials. In this embodiment mode, the quantum well layer is used as a light emitting layer, that is, when a current is formed between the N-type semiconductor layer and the P-type semiconductor layer and passes through the quantum well layer, the quantum well layer emits light.
The N-type semiconductor material layer, the quantum well layer and the P-type semiconductor material layer are sequentially arranged and can be from top to bottom or from bottom to top as required, so that an epitaxial structure of a typical ultraviolet light-emitting diode is formed. In fig. 3, N-type semiconductor material layers, quantum well layers, and P-type semiconductor material layers are sequentially arranged from top to bottom for convenience of description, but those skilled in the art will understand that the upper and lower directions defined in this patent are opposite, and do not refer to the opposite relationship between the directions vertically upward or vertically downward. Of course, the epitaxial structure of the ultraviolet light emitting diode may actually comprise other layers in addition to the above-described structure, as has been shown in this patent with the description comprising such an open type. The specific structure of these layers and their manner of operation are well documented in the prior art and are therefore not described in detail in this patent.
Thin microporous structure layer 4
When the epitaxial structure of the ultraviolet light emitting diode is electrified, part of light rays are emitted by the P-type semiconductor material layer, and in order to guide the light rays to a preset direction and improve the extraction efficiency of ultraviolet light rays, a reflecting layer is required to be additionally arranged behind the P-type semiconductor material layer in the prior art so as to reflect the ultraviolet light rays transmitted in the P-type semiconductor material layer. The reflective layer commonly used in the prior art includes either a DBR mirror or a metallic reflective layer. The DBR mirror has very ideal reflection effect, but the DBR mirror has certain limitation because of the difficulty in processing the multilayer structure and high cost, and the metal reflection layer, namely the reflection layer light of the commonly used Au material, can cause total reflection loss in the process of being reflected by the multilayer material of the chip. Therefore, although the scheme is ideal in theory, the scheme has certain limitation due to total reflection loss in the actual process.
In this embodiment, one surface of the P-type semiconductor material is connected to the quantum well, and a thin microporous layer is disposed on the other surface, and the structure of the thin microporous layer is shown in fig. 4-5. The thin microporous structure refers to a substance with uniform micropores and pore diameter equivalent to the size of a common molecule.
SiO is preferably used for the thin microporous layer in the present embodiment 2 Is made by using SiO 2 The advantages of the method are that the SiO2 is very simple compared with the manufacturing process of the material, the thin layer manufacturing is easy to realize, the process is well realized, the cost is very low, the requirement of total reflection can be met, and in the multi-step process manufacturing, the method is suitable for other processesThe influence is not great. As shown in fig. 4, a thin microporous layer having a microporous structure, that is, hollow regions 5 formed in the layer, and semi-columnar regions 6 formed at portions between hole-type regions are alternately arranged to form a thin microporous structure, and the thickness of the thin microporous layer is only 250±2.5nm. The optical path difference in the ODR mirror is derived from SiO 2 And the thickness of the reflecting light is changed from the Au surface to the phase of the reflecting light, and is formed by SiO 2 The generated phase difference, the phase change amount of Au to reflected light and the coherent enhancement condition of the reflected light of two reflecting interfaces are utilized by a formulaWherein h is SiO 2 Thickness n li Is SiO 2 Refractive index of θ n The phase change of Au to reflected light is carried into ultraviolet wavelength and related data, the reflection is maximum when coherence is enhanced, and SiO is calculated 2 The minimum thickness of (2) is 249nm. The front structure of the micropore structure is shown in fig. 5, and the structure is a skeleton type round-corner polygon, namely a net-shaped structure, the diameter of the round-corner polygon is smaller than 0.15mil, and if the diameter is too large, the reflection effect is not obvious; the distance between the holes is limited in a certain range.
In addition, the thin microporous layer is completely formed into a microporous region, and an electrode matching region is formed on the thin microporous layer in addition to the microporous region, wherein the electrode matching region is matched with the shape of the negative electrode of the ultraviolet light emitting diode chip. As shown in fig. 5, although the thin microporous layer is provided on the positive electrode side of the epitaxial structure in the present embodiment, the shape of the thin microporous layer affects the flatness of the negative electrode side of the epitaxial structure. Therefore, the area of the thinned microporous layer, which is correspondingly matched with the negative electrode, is a solid area, that is, no pore structure exists, so that unevenness caused by micropores below the N-face electrode can be prevented, and unnecessary total reflection can be reduced.
P-type ohmic contact layer 7
One side of the thin microporous structure layer is connected with the P-type semiconductor material layer of the epitaxial structure, the other side of the thin microporous structure layer is connected with the P-type ohmic contact layer, the P-type ohmic contact layer mainly plays a role in forming ohmic contact, the P-type ohmic contact layer is made of metal so as to form ohmic contact, and in the embodiment, the material of the P-type ohmic contact layer is preferably NiAu. NiAu has the function of P-type ohmic contact and also has the function of reflection
Bonding layer 8
The bonding layer 8 is disposed on the opposite side of the P-type ohmic contact layer from the contact side of the thin microporous layer, and preferably Au is used in this embodiment, but other bonding layer materials commonly used can also implement this patent. After the bonding layer is disposed at the above position, the layers are formed integrally with one mirror, thereby achieving an overall excellent reflection effect.
Through the scheme, the omnibearing reflecting mirror (Omni-Directional Reflector, ODR) is composed of a thinned micropore structure layer, a P-type ohmic contact layer and a bonding layer, namely SiO2, niAu and Au. Light emitted by the light-emitting layer is emitted from the N electrode through the reflection of the ODR, and the total reflection and the Fresnel scattering of the thinned structure and the air interface are utilized, so that the absorption of metal of a metal reflector to purple light in the prior art is reduced to the maximum extent, and the light extraction efficiency is improved. The thin structure is designed into a thin micropore structure except for the matching part of the thin structure and the electrode, after cutting, a columnar or semi-columnar perforation area is displayed on the side surface, the probability of outward scattering of photons of the deep ultraviolet light emitting diode converted from a TE mode to a TM mode is increased, the effectiveness of the TE mode is increased, and the light extraction efficiency is further improved. The total reflection and the Fresnel scattering of the thinned micropore structure and the air interface are utilized, so that the metal of the simple metal reflector in the prior art is reduced to absorb a large amount of purple light; meanwhile, compared with the existing distributed Bragg reflection layer and metal reflector, the ODR structure is thinned to the greatest extent, and total reflection loss and metal absorption caused by layer-by-layer reflection are reduced.
In addition, the probability of outward scattering of photons is increased due to the increase of the side perforated area, internal absorption of the quantum well is reduced, the effectiveness of TE modes is increased, and the light extraction efficiency is further improved.
Further, to increase the reflectivity of the ODR, the optical path difference in the ODR mirror is derived from SiO 2 And the thickness of the reflecting light is changed from the Au surface to the phase of the reflecting light, and is formed by SiO 2 The generated phase difference, the phase change amount of Au to reflected light and the coherent enhancement condition of the reflected light of two reflecting interfaces, and SiO during coherent enhancement 2 The minimum thickness of (2) is 249nm.
Bonding substrate 9
The bonding substrate is disposed on the opposite side of the contact side of the bonding layer to the P-type ohmic contact layer, and various bonding substrates in the prior art may be used in the present embodiment. The substrate can be a sapphire substrate, a Si substrate, a W-Cu substrate or a Mo-Cu substrate; further, a back surface of the bonded substrate may be plated with a bright metal to save the amount of noble metal used, including Cr/Ni or an alloy thereof, to save costs.
Coarsening structure 10
The coarsening structure is formed on the upper surface of the N-type semiconductor material, and the coarsening structure is formed by adopting a primary coarsening structure and a secondary coarsening structure, wherein the primary coarsening structure can slightly soak the surface of the N-type semiconductor material by adopting primary coarsening liquid which is hydrogen peroxide, citric acid and water according to a proper proportion, so as to manufacture the N-type ohmic contact layer. The secondary roughening structure is carried out by adopting KOH solution and matching with certain temperature, concentration and time. Through the combination of the primary roughening and the secondary roughening, the secondary roughening liquid KOH is faster and finer in roughening, so that the method is particularly suitable for being used on chips with thin microporous structures, and the influence of the thin micropores on the N electrode is reduced.
Secondary electrode structure
In this embodiment, the pattern of the electrode is matched to the pattern of the thin microporous layer, as described above in this example. In this pattern, a large amount of electrode layer material is required, and if a conventional CrAu primary electrode is used, a thick Au-containing material, at least 2000A, is required to be plated, so that the cost is high, and therefore, in this embodiment, a secondary electrode is provided on the roughened structure to solve the above-mentioned problem.
In the exemplary embodiment shown in fig. 5, the primary electrodes 11 are formed on the roughened structures, and the primary electrodes may be made of a low-cost metal, for example, al/Cr, so that they can be used in a large amount to reduce the cost, and the primary electrodes make ohmic contact. A secondary electrode 12, which is formed on the primary electrode 11, may be made of a noble metal such as Au to improve current stability, is formed on the primary electrode. In order to maintain the contact of the electrodes, the edge of the secondary electrode is preferably wider than the primary electrode, and the connection means between the secondary electrode and the primary electrode comprise a snap-fit, that is to say may comprise one or more of other fixed connection means in addition to a snap-fit connection, which may also be used in combination with the snap-fit connection. One preferred way of engagement is to provide small gripping feet on the lower surface of the secondary electrode to grip the edges of the primary electrode to form a firm contact. By adopting the structure of the secondary electrode, au only needs to be coated by 500A under normal conditions, the area is small, and the requirement of wire bonding can be met by combining Al/Cr/Ni; thereby saving the cost of noble metal to a certain extent. And the structure is more beneficial to electrode adhesion and reduces the electrode stripping phenomenon (Peeling). Thereby providing guarantee and convenience for package routing.
Anti-reflection layer 13
On the N-type semiconductor material, an anti-reflection layer is formed in the area outside the electrode, wherein the anti-reflection layer is preferably made of SiO 2 Or SiN.
Example two
The present embodiment provides a method for manufacturing an ultraviolet light emitting diode chip, and the structure of the ultraviolet light emitting diode chip may be described with reference to the first embodiment. In this embodiment, the main point is how to manufacture the chip to achieve the design performance and provide a sufficient product yield.
The method of the second embodiment includes the following steps:
step one, preparing an ultraviolet light-emitting diode epitaxial structure
Sequentially epitaxially forming a buffer layer, a P-GaN layer, a quantum well layer, an N-AlGaN layer, a u-AlGaN layer, and the like on a substrate to prepare a UV LED base epitaxial layer structure (actually, the structure of one embodiment may also include the above layers, which may be a variation of the first embodiment);
step two, preparing a thinned micropore structure
Depositing a layer of SiO2 with the thickness of 250nm; a mask array of thin micropores is manufactured by using SiO2 through a photoetching technology, and no micropores exist at the corresponding N electrode part;
step three, evaporating NiAu layer
Step four, evaporating bonding layer Au
Step five, manufacturing a bonding substrate
Step six, one-time electrode manufacture
Firstly, slightly soaking with primary roughening liquid comprising hydrogen peroxide, citric acid and water to prepare an N-type ohmic contact layer; manufacturing an ohmic contact electrode Al/Cr; forming N-face ohmic contact;
seventh step, manufacturing a secondary electrode
The N-plane AlGaN roughening of the other region than the primary electrode region is performed with KOH solution, and a secondary electrode, that is, a secondary electrode Au, is formed on the primary electrode.
Step eight, manufacturing an anti-reflection layer
And manufacturing an anti-reflection layer on the N-face semiconductor material in the area outside the electrode.
Protecting the electrode by using methods of SiO2 deposition, photoetching and wet etching; the preparation is carried out for secondary roughening, and the roughening of the N-face AlGaN except electrode protection is carried out by using KOH solution matched with certain temperature, concentration and time.
In addition, it is preferable that the thin microporous layer and the P-type ohmic contact are subjected to 480 ℃ annealing treatment in this embodiment mode for good effect of forming the ODR lens.
Claims (8)
1. An ultraviolet light emitting diode, comprising: the epitaxial structure of the ultraviolet light-emitting diode comprises an N-type semiconductor material layer, a quantum well and a P-type semiconductor material layer; the thickness of the microporous layer is 250+/-2.5 nm, the microporous layer is arranged on the P-type semiconductor material side of the epitaxial structure, and the microporous layer comprises a microporous region and an electrode matching region; forming hollow holes in the micropore areas; the electrode matching area is matched with the shape of the negative electrode of the ultraviolet light-emitting diode chip, and is a solid area; the P-type ohmic contact layer is a metal material layer, and one side of the P-type ohmic contact layer is formed on the microporous layer; a bonding layer disposed on a side of the P-type ohmic contact layer opposite to a contact side of the microporous layer, the bonding layer being made of metal; a bonding substrate arranged on the opposite side of the bonding layer to the contact side of the P-type ohmic contact layer; the microporous layer, the P-type ohmic contact layer and the bonding layer form an omnibearing reflecting mirror; the ultraviolet light emitting diode is in a framework type circular-angle polygon, and the diameter of the circular-angle polygon is smaller than 0.15mil.
2. The ultraviolet light emitting diode of claim 1, wherein the hollow holes are uniformly distributed in the microporous region.
3. The ultraviolet light-emitting diode according to claim 1, wherein a roughened structure is formed on the upper surface of the N-type semiconductor material, the roughened structure comprising a primary roughened structure and a secondary roughened structure, wherein the primary roughened structure has a coarsening particle size greater than that of the secondary roughened structure.
4. An ultraviolet light emitting diode according to claim 3, wherein a primary electrode is formed on the roughened structure, and a secondary electrode is formed on the primary electrode, the secondary electrode being fixedly connected to the primary electrode on the primary electrode.
5. The ultraviolet light-emitting diode according to claim 4, wherein the primary electrode has a thickness greater than a thickness of the secondary electrode.
6. The ultraviolet light-emitting diode according to claim 5, wherein the thickness of the secondary electrode is 500A or less.
7. An ultraviolet light emitting diode according to claim 1, wherein the region outside the electrode has an anti-reflection layer on the N-type semiconductor material.
8. The preparation method of the ultraviolet light-emitting diode chip is characterized by comprising the following steps of: step one, preparing an ultraviolet light-emitting diode epitaxial structure, and sequentially forming an ultraviolet light-emitting semiconductor epitaxial structure on a substrate; preparing a thinned microporous layer, and depositing a layer of SiO2 with the thickness of 250nm +/-2.5 nm; a mask array of thin micropores is manufactured by using SiO2 through a photoetching technology, and no micropores exist at the corresponding N electrode part; step three, evaporating a NiAu layer; evaporating and plating a bonding layer Au; step five, manufacturing a bonding substrate; step six, manufacturing a primary electrode; firstly, soaking with primary roughening liquid comprising hydrogen peroxide, citric acid and water to prepare an N-type ohmic contact layer; manufacturing an ohmic contact electrode Al/Cr; forming N-face ohmic contact; manufacturing a secondary electrode, namely coarsening N-plane AlGaN in other areas except for a primary electrode area by using KOH solution, and forming the secondary electrode on the primary electrode; the microporous layer, the P-type ohmic contact layer and the bonding layer form an omnibearing reflecting mirror; the ultraviolet light emitting diode is in a framework type circular-angle polygon, and the diameter of the circular-angle polygon is smaller than 0.15mil.
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| KR20170123847A (en) * | 2016-04-29 | 2017-11-09 | 엘지이노텍 주식회사 | Ultraviolet Light-Emitting Diode with p-type ohmic contact electrode pattern to enhance the light extraction |
| CN109273573A (en) * | 2018-10-23 | 2019-01-25 | 南昌大学 | A kind of light emitting diode (LED) chip with vertical structure, reflecting electrode and preparation method thereof |
| CN211182231U (en) * | 2019-09-11 | 2020-08-04 | 北京中科优唯科技有限公司 | Ultraviolet light-emitting diode |
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| KR20170123847A (en) * | 2016-04-29 | 2017-11-09 | 엘지이노텍 주식회사 | Ultraviolet Light-Emitting Diode with p-type ohmic contact electrode pattern to enhance the light extraction |
| CN109273573A (en) * | 2018-10-23 | 2019-01-25 | 南昌大学 | A kind of light emitting diode (LED) chip with vertical structure, reflecting electrode and preparation method thereof |
| CN211182231U (en) * | 2019-09-11 | 2020-08-04 | 北京中科优唯科技有限公司 | Ultraviolet light-emitting diode |
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