CN211182232U - Inverted ultraviolet light-emitting diode chip - Google Patents
Inverted ultraviolet light-emitting diode chip Download PDFInfo
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- CN211182232U CN211182232U CN201921515520.0U CN201921515520U CN211182232U CN 211182232 U CN211182232 U CN 211182232U CN 201921515520 U CN201921515520 U CN 201921515520U CN 211182232 U CN211182232 U CN 211182232U
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Abstract
The patent discloses an ultraviolet emitting diode chip of flip-chip includes: the epitaxial structure of the ultraviolet light-emitting diode is characterized in that a plurality of thinning areas are arranged on the P-type ohmic contact layer; the current diffusion layer is arranged on the lower surface of the P-type ohmic contact layer; the surface of the P-type ohmic contact layer is fluctuated to be attached to the P-type ohmic contact layer; a DBR lens layer provided on a lower surface of the current diffusion layer and attached to and along the current diffusion layer with surface undulation of the current diffusion layer; a part of the positive electrode passes through the P-type ohmic contact layer and the current diffusion layer and is in contact with the P-type semiconductor material layer; another part of the positive electrode is in contact with the current diffusion layer; the light-emitting brightness of the ultraviolet light-emitting diode chip is improved through the scheme.
Description
Technical Field
The patent belongs to the technical field of semiconductors, and particularly relates to a flip ultraviolet light-emitting diode and a preparation method thereof.
Background
In the prior art, an epitaxial structure of an ultraviolet light emitting diode is shown in fig. 1, and comprises a substrate 100, and 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 which are sequentially epitaxial from the substrate, wherein a chip structure of a flip-chip ultraviolet light emitting diode formed by the epitaxial structure is shown in fig. 2, and a new substrate is bonded, because P-type GaN has strong absorption to deep ultraviolet light below 10-350nm, the quantum efficiency outside ultraviolet L ED of the flip-chip structure is too low, and the brightness is low.
Disclosure of Invention
The present invention is based on the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an ultraviolet light emitting diode and a method for manufacturing the ultraviolet light emitting diode, so as to overcome at least some of the drawbacks of the prior art.
In order to solve the above problem, the technical scheme provided by the patent comprises:
a flip-chip uv led chip, said chip comprising: the epitaxial structure of ultraviolet emitting diode, ultraviolet emitting diode's epitaxial structure includes: the semiconductor device comprises a substrate, an N-type semiconductor material layer, a multi-quantum well layer, a P-type semiconductor material layer and a P-type ohmic contact layer which are arranged from top to bottom; a plurality of thinning areas are arranged on the P-type ohmic contact layer; the current diffusion layer is arranged on the lower surface of the P-type ohmic contact layer; the surface of the P-type ohmic contact layer is fluctuated to be attached to the P-type ohmic contact layer; a DBR lens layer provided on a lower surface of the current diffusion layer and attached to and along the current diffusion layer with surface undulation of the current diffusion layer; a part of the positive electrode passes through the P-type ohmic contact layer and the current diffusion layer and is in contact with the P-type semiconductor material layer; another part of the positive electrode is in contact with the current diffusion layer; and the negative electrode is in contact with the N-type semiconductor material layer.
Preferably, the positive electrode and the negative electrode are both arranged on the substrate at the bottom of the chip.
Preferably, the thinned region is uniformly disposed on the P-type ohmic contact layer.
Preferably, the P-type ohmic contact layer is a P-type GaN layer.
Preferably, the current diffusion layer is an ITO layer.
Preferably, the substrate includes a sapphire substrate, a Si substrate, or a SiC substrate.
Preferably, the N-type semiconductor material layer comprises N-type AlGaN, and the P-type semiconductor material layer comprises P-type AlGaN.
Preferably, a u-AlGaN layer is further formed between the substrate and the N-type semiconductor material layer.
The preparation method is characterized by comprising the following steps of preparing a UV-L ED basic epitaxial layer structure, preparing a UV-L ED basic epitaxial layer structure on a substrate, preparing a P, N electrode mesa structure, making a P, N electrode mesa on the epitaxial layer through photoetching or ICP etching, preparing window-type P-type GaN, etching a concave-convex shape on a P-type GaN region, preparing an ITO layer, etching ITO on an inner ring of the P-type GaN layer in a P electrode region after the ITO layer is evaporated, leaving an outer ring for carrying a P electrode, preparing a DBR layer, evaporating a DBR layer on the ITO film, removing the DBR layer below the N mesa and the P electrode through etching, and preparing the P, N electrode, wherein P, N electrodes are evaporated by different metals.
Preferably, the method further comprises: step seven, bonding the substrate: the sapphire substrate was thinned by bonding P, N electrodes on the new substrate by a bonding process.
The semiconductor light-emitting diode has a window structure, light emitted by a light-emitting layer quantum well is reduced in light absorption and increased in light projection due to light diffraction and reduction of P-type GaN after passing through the P-type GaN of the window structure, more light is reflected out through DBR reflection, and absorption of the P-type GaN to the light is reduced; the light extraction rate is improved, and secondly, the ITO mainly acts as diffusion current, the traditional large-area metal mirror reflection of a P-type GaN layer is replaced by the DBR, the size of a P-layer metal electrode is reduced, and the production cost is reduced.
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 of which:
FIG. 1 is a prior art epitaxial structure of a vertical structure UV LED;
FIG. 2 is an epitaxial structure of another vertical structure UV LED in the prior art;
fig. 3 is a structural diagram of a flip-chip uv led chip according to an embodiment of the present invention.
Detailed Description
The technical solution described in this patent includes various embodiments and modifications made on the various embodiments. In the present embodiment, these technical solutions are exemplarily set forth by way of the drawings so that the inventive concept, technical features, effects of the technical features, and the like of the present patent become more apparent through the description of the present embodiment. It should be noted, however, that the scope of protection of the patent should obviously not be limited to what is described in the examples, but can be implemented in various ways under the inventive concept of the patent.
In the description of the present embodiment, attention is paid to the following reading references in order to be able to accurately understand the meaning of the words in the present embodiment:
first, in the drawings of the present patent, the same or corresponding elements, layers, etc. will be denoted by the same reference numerals. Therefore, the explanation of the reference numbers or names of elements/layers, etc. that have been presented before may not be repeated later. 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 any order but merely distinguish the elements or elements from one another. Furthermore, the singular forms "a", "an" and "the" do not refer to only the singular but also the plural unless the context clearly dictates otherwise.
Further, the inclusion or inclusion should be understood to be an open description that does not exclude the presence of other elements on the basis of the elements already described; further, when a layer, region or component is referred to as being "formed on", "disposed on" another layer, region or component, the layer, region or component may be directly or indirectly formed on the other layer, region or component, and similarly, when a relationship between two elements is expressed using terms such as connection, connection or the like, it may be either directly or indirectly connected without particular limitation. The term "and/or" connects two elements in a relational or an inclusive relationship.
In addition, for the purpose of illustrating the technical solutions of the present patent, the sizes of the elements described in the drawings of the present patent do not represent the dimensional proportional relationship of the actual elements, and particularly, in the case of the microscopic structures related to the present patent, the sizes, thicknesses, proportions, and the like, are enlarged or reduced for convenience of expression.
Example one
The embodiment provides a flip ultraviolet light emitting diode chip.
The inversion is relative to the normal mounting, a L ED normal mounted chip is the earliest occurring chip structure and is also a chip structure commonly used in a low-power chip, an epitaxial layer of an L ED normal mounted chip is sequentially provided with a P-type semiconductor material layer, a light emitting layer, an N-type semiconductor material layer and a substrate layer from top to bottom, and in a L ED chip of the normal mounting structure, an electrode is positioned above the epitaxial layer, so that the electrode can influence the light emission, so in the prior art, a L ED chip structure of the inversion is proposed, the N-type semiconductor material of an L ED chip of the inversion is provided with the light emitting layer and the P-type semiconductor layer above and below the N-type semiconductor layer, and the light emitting layer and the P-type semiconductor material are provided with electrodes and other structures, so that the electrodes are prevented from blocking ultraviolet rays.
For example, the prior art shows an ultraviolet light emitting diode, which generally refers to L ED with a central light emitting wavelength below 400nm, but sometimes refers to near ultraviolet L ED when the central light emitting wavelength is more than 380nm, and refers to deep ultraviolet L ED when the central light emitting wavelength is shorter than 300nm, but all of which are in the category of ultraviolet light emitting diodes referred to in the present embodiment.
Epitaxial structure of ultraviolet light-emitting diode
In this embodiment, various epitaxial structures of ultraviolet light emitting diodes capable of generating ultraviolet light can be exemplified. Generally, the epitaxial structure of the ultraviolet light emitting diode includes: the semiconductor device comprises a substrate, an N-type semiconductor material layer, a multi-quantum well layer and a P-type semiconductor material layer. In fact, although other layers are described in the following description of the present application for the purpose of possibly facilitating better technical effects in engineering implementation, it is understood that when the epitaxial structure of the ultraviolet light emitting diode is described only by itself and not by other limitations in this patent, it refers to the substrate, the N-type semiconductor material layer, the mqw layer, and the P-type semiconductor material layer, so as to be able to generate ultraviolet light after being energized. As to the material structures of the substrate, the N-type semiconductor material layer, the multiple quantum well layer, and the P-type semiconductor material layer, and how they emit the semiconductor light, many embodiments can be referred to in the prior art, and thus they are not described one by one in this embodiment.
For the purpose of generating ultraviolet light, in the present embodiment, the N-type semiconductor material layer and the P-type semiconductor material layer both include AlGaN material, and according to the existing research, a PN junction formed by AlGaN material is a more ideal semiconductor material layer of the ultraviolet light emitting diode. Or equivalent materials may be substituted for AlGaN materials based on other studies, as would be apparent to one skilled in the art.
However, in order to make the inventive concept of the present patent more concretely appreciated by those skilled in the art with reference to specific examples, the present embodiment will be described in detail with reference to an example shown in fig. 3. However, it should be noted that, in the description of the specific example, if the technical means and technical effects of a specific component \ module and other elements are described, the element should be regarded as a further improvement of the technical solution within the framework of the present general inventive concept in the example, and should not be understood as a common general knowledge of conventional material selection, parameter selection, structural design and the like.
The epitaxial structure of the uv led in the example of fig. 3 includes:
substrate 1, said substrate preferably being a sapphire substrate, i.e. Al2O3Is a substrate of material used to form other epitaxial layers thereon. Except for Al2O3Besides the substrate of material, the substrate material of SiC, Si, etc. can be used in the field, which is under different environmentsSuch as material replacement in a laboratory environment.
And the buffer layer 2 is formed below the substrate, in the example shown in fig. 3, a u-AlN/AlGaN layer is used as the buffer layer, and the u-AlN/AlGaN layer is a non-doped aluminum nitride/gallium nitride layer formed on the substrate and plays roles in improving epitaxial growth quality and reducing epitaxial growth defects. In fact, the present embodiment is not limited to u-AlN/AlGaN, and other materials may be used to improve the epitaxial quality and reduce the epitaxial defects.
And an N-AlGaN layer formed under the u-AlN/AlGaN layer, wherein the AlGaN functions as a cathode in the N-type semiconductor material layer 3, that is, the AlGaN can form a large amount of free electrons after being electrified and flow to a cathode.
And a quantum well MQW layer 4, wherein a multi-quantum well MQW layer is formed under the N-type semiconductor material layer, and the multi-quantum well layer is a multi-quantum well layer. A quantum well refers to a potential well of electrons or holes with quantum confinement effect formed by spacing 2 different semiconductor materials. If the barrier layers in a quantum well are thick enough that there is little coupling between the carrier transfer functions between adjacent wells, the multilayer structure will form many separate quantum wells, referred to as multiple quantum wells. In this embodiment mode, the multiple quantum well MQW layer is used as a light-emitting layer, that is, after a current is formed between the N-type semiconductor layer and the P-type semiconductor layer through the multiple quantum well MQW layer, the multiple quantum well MQW layer emits light.
And a P-type semiconductor material layer 5 formed under the multiple quantum well layer, and in the present embodiment, the P-type semiconductor material layer preferably uses a P-AlGaN layer so as to emit ultraviolet rays.
And a P-type ohmic contact layer 6 formed on the lower surface of the P-type semiconductor material layer, wherein in the embodiment, the P-type ohmic contact layer is formed. In this embodiment, a P-type GaN layer is used as the P-type ohmic contact layer. Although P-type GaN is a material for forming an ohmic contact, which is a preferable positive electrode in an ultraviolet semiconductor light emitting diode, P-type GaN absorbs ultraviolet light too much, thereby affecting the brightness of the ultraviolet light emitting diode, and particularly, in a flip-chip ultraviolet light emitting diode, since light is reflected by a metal layer behind a P layer to emit light, it corresponds to a case where light has multiple optical paths in the P-type GaN layer, and thus the absorption of ultraviolet light by P-type GaN significantly affects the brightness of the external light emitting diode. Not only the improvement of the reflective layer is needed to improve the brightness of the uv led, but also how to reduce the absorption of uv light by the P-type GaN layer is another important consideration.
In this embodiment, as shown in fig. 3, a plurality of thinned regions 7 are provided on the P-type GaN layer, i.e., thinned regions having a thickness smaller than that of other regions of GaN. The thinning area can be a recess or a through hole. That is, the thickness to be thinned may vary depending on the wavelength of light, the thickness of each layer, and the thickness to be thinned is dependent on the wavelength of light because light passing through such alternating thinned regions interferes or diffracts, and the through-hole is required when the thickness to be thinned exceeds the thickness of the P-type GaN layer. The plurality of thinned regions are uniformly arranged so as to form uniform light distribution. By providing the thinned P-type GaN layer, the absorption of ultraviolet light is substantially reduced, thereby improving the luminance of the ultraviolet light emitting diode chip.
Current diffusion layer 8
However, the P-type GaN layer reduces the absorption of ultraviolet light after being provided with the thinning region, but the existence of the recess and the through hole can bring the problem of uneven current, so that the ITO layer, namely the indium tin oxide layer, is arranged on the lower surface of the P-type GaN layer along the shape in the embodiment, and the indium tin oxide layer mainly functions as diffusion current, namely, the current transmitted by the electrode is uniformly diffused to the surface of the whole anode semiconductor material, thereby avoiding the current concentration, and being beneficial to the stability of the light emitting quality of the semiconductor material. The optimal thickness of the ITO film layer can be calculated by different transmission wavelengths and ITO refractive indexes.
DBR lens layer 9
The lower surface of the ITO layer is provided with a DBR lens layer, the DBR is a periodic structure formed by two insulating materials with different refractive indexes which are alternately arranged in an ABAB mode, the DBR has a strong reflection effect, the traditional large-area metal mirror reflection of a P-type GaN layer is replaced by the DBR, the size of a P-layer metal electrode is reduced, and the production cost is reduced. The material (such as SiO2 and TaO), thickness and number of the DBR thin film layers can be calculated according to different transmission wavelengths and refractive indexes of the materials;
electrode for electrochemical cell
And the positive electrode 10 is provided with one end arranged on the substrate 12 and the other end connected with the P-type P-AlGaN layer, and is also connected with the ITO layer, so that the ITO layer is in contact with the electrode, and a good current dispersion effect is formed except that the use amount of noble metals is reduced due to the use of the DBR layer.
And the negative electrode 11 is arranged above the substrate at one end and is connected with the N-type semiconductor material at the other end.
Example two
The present embodiment provides a method for manufacturing a flip-chip ultraviolet light emitting diode chip, and the structure of the flip-chip ultraviolet light emitting diode chip is described with reference to the first embodiment. In the present embodiment, the main point is how to prepare the above chip to achieve the designed performance and provide a chip with sufficient yield.
Preparing a UV-L ED basic epitaxial layer structure, namely sequentially extending a buffer layer, a P-GaN layer, a quantum well layer, an N-AlGaN layer and a u-AlGaN layer on a substrate to prepare the UV L ED basic epitaxial layer structure;
step two, preparing P, N electrode mesa structure: making P, N electrode mesa on the epitaxial layer by photolithography and ICP etching; the lithography technique includes a general lithography technique, an electron beam lithography technique, a nanoimprint technique, or a holographic lithography technique.
Step three, preparing window type P-type GaN: etching the P-type GaN region into a concave-convex shape by photoetching and ICP etching (or wet etching);
step four, preparing ITO: after ITO evaporation is finished, etching ITO on the inner ring of a P-type GaNP electrode area through photoetching and wet etching technologies, and reserving the outer ring for carrying a P electrode;
step five, preparing DBR: evaporating DBR layer on ITO film, etching off DBR under N mesa and P electrode by photoetching and etching technique,
step six, preparation of P, N electrode: p, N electrodes are respectively evaporated with different metals,
step seven, bonding the substrate: and P, N electrodes are bonded on the new substrate through a bonding process, and the sapphire substrate is thinned, so that the preparation of the chip is completed.
Compared with the prior art, the invention has the following substantive characteristics and remarkable progress: the semiconductor light-emitting diode has a window structure, light emitted by a light-emitting layer quantum well is reduced in light absorption and increased in light projection due to light diffraction and reduction of P-type GaN after passing through the P-type GaN of the window structure, more light is reflected out through DBR reflection, and absorption of the P-type GaN to the light is reduced; the light extraction rate is improved, and secondly, the ITO mainly acts as diffusion current, the traditional large-area metal mirror reflection of a P-type GaN layer is replaced by the DBR, the size of a P-layer metal electrode is reduced, and the production cost is reduced.
Claims (8)
1. A flip-chip uv led chip, said chip comprising:
the epitaxial structure of ultraviolet emitting diode, ultraviolet emitting diode's epitaxial structure includes: the semiconductor device comprises a substrate, an N-type semiconductor material layer, a multi-quantum well layer, a P-type semiconductor material layer and a P-type ohmic contact layer which are arranged from top to bottom; a plurality of thinning areas are arranged on the P-type ohmic contact layer;
the current diffusion layer is arranged on the lower surface of the P-type ohmic contact layer; the surface of the P-type ohmic contact layer is fluctuated to be attached to the P-type ohmic contact layer;
a DBR lens layer disposed on a lower surface of the current diffusion layer and attached to the current diffusion layer with surface undulation of the current diffusion layer;
a part of the positive electrode passes through the P-type ohmic contact layer and the current diffusion layer and is in contact with the P-type semiconductor material layer; another part of the positive electrode is in contact with the current diffusion layer;
and the negative electrode is in contact with the N-type semiconductor material layer.
2. The flip-chip uv led chip of claim 1, wherein said positive electrode and said negative electrode are disposed on a substrate at the bottom of said chip.
3. The flip-chip uv led chip of claim 1, wherein said thinned region is uniformly disposed on said P-type ohmic contact layer.
4. The UV LED flip-chip according to claim 3, wherein the P-type ohmic contact layer is a P-type GaN layer.
5. The flip-chip uv led chip of claim 1, wherein said current spreading layer is an ITO layer.
6. The flip-chip uv led chip of claim 1, wherein said substrate comprises a sapphire substrate, a Si substrate, or a SiC substrate.
7. The flip-chip uv led chip of claim 1, wherein the N-type semiconductor material layer comprises N-type AlGaN and the P-type semiconductor material layer comprises P-type AlGaN.
8. The flip-chip uv led chip of claim 1, wherein a u-AlGaN layer is further formed between the substrate and the N-type semiconductor material layer.
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| CN201921515520.0U CN211182232U (en) | 2019-09-11 | 2019-09-11 | Inverted ultraviolet light-emitting diode chip |
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| CN201921515520.0U CN211182232U (en) | 2019-09-11 | 2019-09-11 | Inverted ultraviolet light-emitting diode chip |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110931609A (en) * | 2019-09-11 | 2020-03-27 | 北京中科优唯科技有限公司 | Inverted ultraviolet light-emitting diode and preparation method thereof |
| CN113078248A (en) * | 2021-03-30 | 2021-07-06 | 芜湖启迪半导体有限公司 | UVC semiconductor light-emitting device and manufacturing method thereof |
| CN114937724A (en) * | 2022-03-31 | 2022-08-23 | 嘉兴鼎镓半导体有限公司 | UVC-LED chip and manufacturing method thereof |
-
2019
- 2019-09-11 CN CN201921515520.0U patent/CN211182232U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110931609A (en) * | 2019-09-11 | 2020-03-27 | 北京中科优唯科技有限公司 | Inverted ultraviolet light-emitting diode and preparation method thereof |
| CN113078248A (en) * | 2021-03-30 | 2021-07-06 | 芜湖启迪半导体有限公司 | UVC semiconductor light-emitting device and manufacturing method thereof |
| CN114937724A (en) * | 2022-03-31 | 2022-08-23 | 嘉兴鼎镓半导体有限公司 | UVC-LED chip and manufacturing method thereof |
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