CN114725265A - Inverted deep ultraviolet diode and preparation method thereof - Google Patents
Inverted deep ultraviolet diode and preparation method thereof Download PDFInfo
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- CN114725265A CN114725265A CN202210643048.9A CN202210643048A CN114725265A CN 114725265 A CN114725265 A CN 114725265A CN 202210643048 A CN202210643048 A CN 202210643048A CN 114725265 A CN114725265 A CN 114725265A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers 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 having potential barriers 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
- H01L33/40—Materials therefor
- H01L33/405—Reflective materials
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- 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 having potential barriers 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 having potential barriers 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
- H01L33/40—Materials therefor
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The disclosure belongs to the technical field of semiconductors, and particularly relates to a flip deep ultraviolet diode and a preparation method of the flip deep ultraviolet diode. The flip deep ultraviolet diode comprises a diode epitaxial surface, and an N electrode and a P electrode which are arranged on the diode epitaxial surface, wherein the N electrode comprises a metal film formed by copper-aluminum alloy and at least one elementary substance film formed by one of Cr, Ni, Au, Ti and Pt, which is arranged on the copper-aluminum alloy metal film; the P electrode comprises a NiO film and a transparent electrode positioned on the NiO film, the transparent electrode comprises an ITO film positioned at the bottom layer, and Ga arranged on the ITO film2O3A film; the N electrode with be provided with the thickening electrode on the P electrode, the thickening electrode includes the high reflection metal film who is formed by one of Al, Ag and Rh. To reduce the risk of leakage, prevent light decay, reduce the power consumption of the diode and improve the brightness of the diodeThe effect of the degree.
Description
Technical Field
The disclosure belongs to the technical field of semiconductors, and particularly relates to a flip deep ultraviolet diode and a preparation method of the flip deep ultraviolet diode.
Background
In the prior art, an Al metal film is often used for the N electrode to achieve ohmic contact, but the metal aluminum may generate electron migration, that is, the electron flow may bring momentum to metal atoms, so that the metal atoms flow around away from the metal surface, resulting in formation of voids (void) or hillocks (hillocks) on the metal film surface, which may cause a decrease in reflectivity of the flip-chip deep ultraviolet diode and an increase in risk of light attenuation, and may even cause a short circuit of the whole diode. In addition, the P electrode is usually a metal electrode, so that the light extraction rate of the diode is limited.
Disclosure of Invention
The present disclosure is proposed based on the above requirements of the prior art, and the technical problem to be solved by the present disclosure is to provide a flip deep ultraviolet diode and a method for manufacturing the flip deep ultraviolet diode so as to optimize the usage performance of the diode and improve the usage effect of the diode.
In order to solve the above problem, the technical solution provided by the present disclosure includes:
the flip deep ultraviolet diode comprises a diode epitaxial surface, and an N electrode and a P electrode which are arranged on the diode epitaxial surface, wherein the N electrode comprises a metal film formed by copper-aluminum alloy and at least one elementary substance film formed by one of Cr, Ni, Au, Ti and Pt, which is arranged on the copper-aluminum alloy metal film; the P electrode comprises a NiO film and a transparent electrode positioned on the NiO film, the transparent electrode comprises an ITO film positioned at the bottom layer, and Ga arranged on the ITO film2O3A film; the N electrode with be provided with the thickening electrode on the P electrode, the thickening electrode includes the high reflection metal film who is formed by one of Al, Ag and Rh.
By using the N electrode with the copper-aluminum alloy, Al ohmic contact is used, and meanwhile, the stability of the metal copper can effectively inhibit the electron migration of the metal aluminum in the use process of the deep ultraviolet diode, so that the leakage wind is reducedDanger and prevention of light decay; the P electrode comprises a NiO film, so that ohmic contact is effectively improved, the voltage of the flip deep ultraviolet diode is reduced, the using power consumption of the flip deep ultraviolet diode is reduced, and the service life of the diode is prolonged to a certain extent. Further, an ITO film and Ga are provided on the NiO film2O3The film to make flip-chip dark ultraviolet diode have higher dark ultraviolet ray transmissivity, and then improve flip-chip dark ultraviolet diode's luminance.
Preferably, the ITO film and the Ga are2O3The films are connected; the thickness of the ITO film is 3nm-10nm, and the Ga2O3The thickness of the film is 50nm-300 nm.
The thickness of the ITO film is 3nm-10nm, and the absorption of deep ultraviolet light is effectively reduced by the thin ITO film. And Ga is stacked on the ITO film2O3Film formed by said ITO film and said Ga2O3The films are stacked to enhance the light transmittance of deep ultraviolet light, so that the brightness of the flip deep ultraviolet diode is improved by 10% -30%.
Preferably, the transparent electrode includes at least two ITO films and at least one Ga film2O3A film of the ITO film having a thickness of 3nm to 10nm, the Ga2O3The thickness of the film is 3nm-10 nm; the ITO film and the Ga2O3The membranes are arranged in a staggered and stacked mode; the thickness of the transparent electrode is 100nm-300 nm.
Through the setting, the light transmittance of the inverted deep ultraviolet diode is improved, and the light-emitting brightness of the diode is further enhanced.
Preferably, the weight percentage of copper in the copper-aluminum alloy is 1-5%.
Because the metal Cu has higher stability, the electron migration of the metal aluminum in the using process of the deep ultraviolet diode is effectively inhibited while Al ohmic contact is used, so that the electric leakage risk is reduced, and the light attenuation is prevented.
Preferably, the thickness of the NiO is 5nm to 20 nm.
So set up in order effectively to improve ohmic contact, and then realize reducing the effect of flip-chip deep ultraviolet diode voltage, reduce flip-chip deep ultraviolet diode's use consumption simultaneously to prolong the life of diode to a certain extent.
Also provided is a method for manufacturing a flip-chip deep ultraviolet diode, comprising: evaporating and plating on an N electrode table board of a semiconductor epitaxial material to form a plurality of layers of metal films, and annealing to form ohmic contact to obtain an N electrode, wherein the metal films comprise a metal film formed by copper-aluminum alloy and at least one elementary substance film formed by one of Cr, Ni, Au, Ti and Pt, which is arranged on the copper-aluminum alloy metal film, and a Ni metal film is formed on a P electrode table board; forming a NiO film after one of aqua regia, hydrochloric acid or nitric acid is used for treatment; forming a transparent electrode on the NiO film; the process of forming the transparent electrode includes sputtering the substrate to obtain an ITO film, and sputtering Ga on the ITO film2O3Film, and anneal to form ohmic contact to get P electrode; respectively forming thickened electrodes on the surfaces of the N electrode and the P electrode by evaporation; the thickened electrode comprises a plurality of metal films, and the metal films comprise high-reflection metal films formed by evaporation of one of Al, Ag and Rh.
By using the N electrode with the copper-aluminum alloy, Al ohmic contact is used, and meanwhile, the stability of the metal copper can effectively inhibit the electron migration of the metal aluminum in the using process of the deep ultraviolet diode, so that the electric leakage risk is reduced, and light decay is prevented; the P electrode comprises a NiO film, so that ohmic contact is effectively improved, the voltage of the flip deep ultraviolet diode is reduced, the using power consumption of the flip deep ultraviolet diode is reduced, and the service life of the diode is prolonged to a certain extent. Further, an ITO film and Ga are provided on the NiO film2O3The film to make flip-chip dark ultraviolet diode have higher dark ultraviolet ray transmissivity, and then improve flip-chip dark ultraviolet diode's luminance.
Preferably, the transparent electrode includes an ITO film of 3nm to 10nm thickness and Ga of 50nm to 300nm thickness on the ITO film2O3A film; the ITO film and the Ga2O3The films are arranged in a connecting way.
The thickness of the ITO film is 3nm-10nm, and the ITO film is thinnerEffectively reduces the absorption of deep ultraviolet light. And Ga is stacked on the ITO film2O3Film formed by the ITO film and the Ga2O3The films are stacked to enhance the light transmittance of deep ultraviolet light, so that the brightness of the flip deep ultraviolet diode is improved by 10% -30%.
Preferably, the transparent electrode includes an ITO film having a thickness of 3nm to 10nm and Ga having a thickness of 3nm to 10nm2O3A film; the ITO film and the Ga2O3The films are stacked on each other; the thickness of the transparent electrode is 100nm-300 nm.
Through the setting, the light transmittance of the inverted deep ultraviolet diode is improved, and the light-emitting brightness of the diode is further enhanced.
Preferably, the thickness of the Ni metal film formed on the P electrode mesa is 1nm to 50 nm.
Preferably, the weight percentage of copper in the copper-aluminum alloy is 1-5%.
Because the metal Cu has higher stability, the electron migration of the metal aluminum in the using process of the deep ultraviolet diode is effectively inhibited while Al ohmic contact is used, so that the electric leakage risk is reduced, and the light attenuation is prevented.
Compared with the prior art, the N electrode with the copper-aluminum alloy is used, so that Al ohmic contact is used, and meanwhile, the stability of the metal copper can effectively inhibit the electron migration of the metal aluminum in the using process of the deep ultraviolet diode, so that the electric leakage risk is reduced, and light decay is prevented; the P electrode comprises a NiO film, so that ohmic contact is effectively improved, the voltage of the flip deep ultraviolet diode is reduced, the using power consumption of the flip deep ultraviolet diode is reduced, and the service life of the diode is prolonged to a certain extent. Further, an ITO film and Ga are provided on the NiO film2O3The film to make flip-chip dark ultraviolet diode have higher dark ultraviolet ray transmissivity, and then improve flip-chip dark ultraviolet diode's luminance.
Drawings
In order to more clearly illustrate the embodiments of the present specification or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present specification, and other drawings can be obtained by those skilled in the art according to the drawings.
FIG. 1 is a diagram of a basic epitaxial surface in an embodiment of the present disclosure;
FIG. 2 is a diagram of an etched epitaxial surface structure in an embodiment of the present disclosure;
FIG. 3 is a block diagram of an embodiment of the present disclosure after fabrication of an N electrode;
FIG. 4 is a block diagram illustrating the fabrication of a P electrode according to an embodiment of the present disclosure;
FIG. 5 is a diagram illustrating a structure of a stacked and thickened electrode according to an embodiment of the present disclosure;
FIG. 6 is a diagram illustrating a structure after a passivation layer is disposed in an embodiment of the disclosure;
FIG. 7 is a diagram of a flip chip deep ultraviolet diode layer structure in an embodiment of the disclosure;
fig. 8 is a flowchart of steps for fabricating a flip-chip deep ultraviolet diode in an embodiment of the present disclosure.
Reference numerals are as follows:
1. a substrate; 2. an AlN layer; 3. an n-AlGaN layer; 4. a quantum well layer; 5. a P-type electron blocking layer; 6. a p-AlGaN layer; 7. an N electrode; 8. a NiO film; 9. a transparent electrode; 10. thickening the electrode; 11. a passivation layer; 12. and a PAD electrode.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the embodiments of the present disclosure, it should be noted that, unless otherwise explicitly specified or limited, the term "connected" should be interpreted broadly, and may include, for example, a fixed connection, a detachable connection, an integrated connection, a mechanical connection, an electrical connection, a direct connection, and an indirect connection through an intermediate medium. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.
The terms "top," "bottom," "above … …," "below," and "on … …" as used throughout the description are relative positions with respect to components of the device, such as the relative positions of the top and bottom substrates 1 inside the device. It will be appreciated that the devices are multifunctional, regardless of their orientation in space.
For the purpose of facilitating understanding of the embodiments of the present application, the following description will be made in terms of specific embodiments with reference to the accompanying drawings, which are not intended to limit the embodiments of the present application.
Example 1
This embodiment provides a flip chip deep ultraviolet diode, see fig. 7.
The flip deep ultraviolet diode comprises a substrate 1, an epitaxial layer, an N electrode 7 and a P electrode which are arranged on the epitaxial layer, a thickened electrode 10, a passivation layer 11 and a PAD electrode 12 which are covered on the N electrode 7 and the P electrode.
The epitaxial layer is arranged on the substrate 1 and is an AlN layer 2, an n-AlGaN layer 3, a quantum well layer 4 (MQW), a P-type electron barrier layer 5 (EBL) and a P-AlGaN layer 6 from bottom to top respectively. An N electrode 7, a thickened electrode 10, a passivation layer 11 and a PAD electrode 12 are sequentially arranged on the N-AlGaN layer 3; and a P electrode, a thickened electrode 10, a passivation layer 11 and a PAD electrode 12 are sequentially arranged on the P-AlGaN layer 6.
The N electrode 7 has a multilayer structure, and is provided with a Cr metal film, a copper aluminum alloy film and a metal simple film formed by at least one metal of Cr, Ni, Au, Ti and Pt from top to bottom in sequence. Specifically, the Cr metal film is provided on the N-AlGaN layer 3 to bond the N electrode mesa and the metal film on the Cr metal film. The Cr metal film is provided with a copper-aluminum alloy film, and the weight of metal copper in the copper-aluminum alloy film accounts for 1-5 percent of the specific gravity. In the prior art, an Al metal film is stacked on a Cr metal film, and when a flip deep ultraviolet diode is used, the metal aluminum may generate electron migration, that is, because the flow of electrons may bring momentum to metal atoms, so that the metal atoms are separated from the metal surface and flow around, resulting in formation of voids (void) or hillocks (hillock) on the surface of the metal film, which may cause a decrease in reflectivity of the flip deep ultraviolet diode and an increase in risk of light attenuation, and in addition, may even cause a short circuit of the whole diode. In the embodiment, the copper-aluminum alloy is used for replacing metal Al, and since the metal Cu has higher stability, the electron migration of the metal aluminum in the use process of the deep ultraviolet diode is effectively inhibited while Al ohmic contact is used, so that the electric leakage risk is reduced, and light decay is prevented. And a metal single film formed by at least one metal of Cr, Ni, Au, Ti and Pt is superposed on the copper-aluminum alloy film. Specifically, one of the metals is evaporated on the copper-aluminum alloy metal film to form a first metal simple substance film, and other metal simple substances can be continuously evaporated on the first metal simple substance film, so that one metal simple substance film is formed each time the metal simple substances are evaporated. Ohmic contact is formed under the combined action of metal Cr, copper-aluminum alloy and at least one metal of Cr, Ni, Au, Ti and Pt.
The P electrode has a multilayer structure, and the NiO film 8 is arranged on the upper surface of the P-AlGaN layer 6 so as to effectively improve ohmic contact, further realize the effect of reducing the voltage of the flip deep ultraviolet diode, and simultaneously reduce the use power consumption of the flip deep ultraviolet diode so as to prolong the service life of the diode to a certain extent. The thickness of the NiO film 8 is 5nm-20 nm.
A transparent electrode 9 is arranged on the NiO film 8, and the transparent electrode 9 comprises an ITO film and Ga2O3And the ITO film is positioned at the bottom layer of the transparent electrode 9 and is in contact with the NiO, the thickness of the ITO film is 3nm-10nm, and the absorption of deep ultraviolet light is effectively reduced by the thinner ITO film. Ga is stacked on the ITO film2O3Film, Ga2O3The material can penetrate through more deep ultraviolet rays, so that the flip deep ultraviolet diode in the embodiment has higher deep ultraviolet ray transmittance, and further the improvement is realizedThe brightness of the flip-chip deep ultraviolet diode is high. Wherein the ITO film is an ohmic contact layer, the Ga2O3The film is a current spreading layer. In one embodiment of this embodiment, the transparent electrode 9 has two films, i.e. an ITO film located at the bottom layer of the transparent electrode 9 and Ga located at the top layer of the transparent electrode 92O3A membrane, and the Ga2O3The film is stacked in contact with the ITO film, the Ga2O3The thickness of the film is 50nm-300 nm. In another embodiment of this embodiment, the transparent electrode 9 comprises a multilayer film, specifically, an ITO film on the bottom layer of the transparent electrode 9 and Ga disposed on the ITO film2O3Film of Ga2O3The thickness of the film is 3nm-10 nm. The ITO film and the Ga2O3The films are arranged in an intersecting stack, and the films and the transparent electrode form a transparent electrode 9, and the thickness of the transparent electrode 9 is 100nm-300 nm. Through the ITO film and the Ga2O3The setting of piling up of membrane, the luminousness of reinforcing deep ultraviolet light, and then improve flip-chip deep ultraviolet diode's luminance, further, can promote 10% -30% luminance.
And thickened electrodes 10 are arranged on the N electrode 7 and the P electrode. The thickened electrode 10 comprises a plurality of layers of metal films, the bottom layer of the thickened electrode 10 is a metal adhesive film, and the metal adhesive film is in contact with the N electrode 7 and the P electrode. The metal adhesion film is formed of metal Cr or metal Ni, and the thickness thereof is maintained at 1nm-5 nm. And a high-reflection metal film is superposed on the metal adhesive film, is formed by one of high-reflection metals Al, Ag and Rh, and has a thickness of 50-200 nm. Above-mentioned setting will not cause the influence to ohmic contact's characteristic, is setting up transparent electrode 9 simultaneously and improving under the prerequisite of the luminousness of dark ultraviolet light, improves the reflectivity of light through the high reflection metallic film, and then improves flip-chip dark ultraviolet diode's luminous luminance once more for flip-chip dark ultraviolet diode has higher optical efficiency. And other metal films can be continuously superposed on the high-reflection metal film.
And arranging a passivation layer 11 in the region of the formed flip-chip deep ultraviolet diode except the first region and the second region, wherein the passivation layer 11 is formed by one of silicon oxide, silicon nitride or aluminum oxide. The first region is located above the P electrode, the second region is located above the N electrode 7, so that a first space formed by taking the upper surface of the thickened electrode 10 where the first region is located as the bottom surface and surrounding the side surface of the passivation layer 11 as the side surface is formed, a second space formed by taking the upper surface of the thickened electrode 10 where the second region is located as the bottom surface and surrounding the side surface of the passivation layer 11 as the side surface is formed. The first space and the second space are used to dispose the PAD electrode 12.
The PAD electrode 12 is arranged in the first space and the second space, the PAD electrode 12 comprises multiple metal films, the metal films comprise multiple metal single-film films formed by multiple metals such as Cr, Ni, Ti, Pt, Au, Sn and the like, the uppermost metal film of the PAD electrode 12 is a metal film formed by Au or a metal film formed by Sn, and the PAD electrode and the second space are arranged for subsequent packaging eutectic crystal use.
Example 2
This example provides a method for fabricating a flip-chip deep ultraviolet diode, and refers to fig. 1-8.
A base epitaxial surface is prepared on a substrate 1.
An AlN layer 2, an n-AlGaN layer 3, a quantum well layer 4 (MQW), a P-type electron blocking layer 5 (EBL), and a P-AlGaN layer 6 are provided in this order from the bottom up on the substrate 1, as shown in fig. 1.
And etching the basic epitaxial surface to obtain a P electrode table top and an N electrode table top.
Referring to fig. 2, P electrode mesas and N electrode mesas are obtained on the base epitaxial surface by photolithography and ICP etching. The photoetching transfers the pattern of the photoetching mask plate to the photoetching glue of the substrate, and then the pattern on the photoetching glue is transferred to the substrate through etching. Through the process, the exposed upper surface of the P electrode mesa is the surface of the P-AlGaN layer 6, and the exposed upper surface of the N electrode mesa is the surface of the N-AlGaN layer 3.
And preparing the N electrode 7 on the N electrode table board, wherein the preparation process comprises photoetching, metal evaporation and stripping of partial metal and photoresist.
Referring to fig. 3, photolithography is performed on the upper surface of the n-AlGaN layer 3, specifically, a region where metal needs to be deposited is reserved by photolithography, and a photoresist is deposited on a region where metal does not need to be deposited.
And then, plating a film on the upper surface of the N electrode table-board by metal evaporation to form a multi-layer metal film, wherein the metal film comprises a metal film formed by copper-aluminum alloy and a metal single-layer film formed by at least one metal of Cr, Ni, Au, Ti and Pt, and the metal single-layer film is arranged on the copper-aluminum alloy metal film. Specifically, Cr is used for carrying out first-layer metal evaporation on an N electrode table board so as to adhere the N electrode table board and a metal film on a Cr metal film, and the evaporation of copper-aluminum alloy is continuously carried out on the Cr metal film, wherein the metal copper in the copper-aluminum alloy occupies 1-5% of the specific gravity. In the prior art, metal Al is usually superimposed on the Cr metal film, but during the use of the flip-chip deep ultraviolet diode, the metal Al generates electron migration, that is, the metal atom is separated from the metal surface and flows around due to momentum brought by the flow of electrons, so that a pit (void) or a mound (hillock) is formed on the surface of the metal film, which causes the reflectance of the flip-chip deep ultraviolet diode to decrease and increases the risk of light decay, and furthermore, even causes a short circuit of the whole diode. In the embodiment, the copper-aluminum alloy is used to replace metal Al, and since metal Cu has high stability, the Al is used for ohmic contact, and meanwhile, the electron migration of metal aluminum in the use process of the deep ultraviolet diode is effectively inhibited, so that the electric leakage risk is reduced, and the light decay is prevented. And evaporating at least one metal of Cr, Ni, Au, Ti and Pt again on the copper-aluminum alloy metal film to form a metal single film. For example, a first metal simple substance film is formed by evaporating one of the above metals on a copper-aluminum alloy metal film, and other metal simple substances may be evaporated on the first metal simple substance film, wherein a layer of metal simple substance film is formed by one evaporation of the metal simple substances. Ohmic contact is formed under the combined action of metal Cr, copper-aluminum alloy and at least one metal of Cr, Ni, Au, Ti and Pt.
Since the metal film formed by metal evaporation will cover the entire area of the upper surface of the N-electrode mesa and the semiconductor needs to expose the metal to form ohmic contact, the metal film covering the photoresist is removed by lift-off while the photoresist is removed to leave the metal on the upper surface of the N-electrode mesa as the forming N-electrode 7.
The N-electrode 7 is annealed at 750-1000 c to form an ohmic contact without generating a significant additional resistance and without significantly changing the equilibrium carrier concentration inside the semiconductor diode.
And preparing the P electrode on the P electrode table top, wherein the preparation process comprises photoetching, film coating and sputtering of the transparent electrode 9.
Referring to fig. 4, photolithography and a metal plating film are performed on the upper surface of the p-AlGaN layer 6, the metal plating film is completed using metal Ni, and a Ni metal film of 1nm to 50nm is formed on the surface of the p-AlGaN layer 6. And placing the formed whole structure in aqua regia, hydrochloric acid or nitric acid for soaking for 1-5 min to obtain a NiO film 8, wherein the thickness of the NiO film 8 is 5-20 nm. Set up transparent electrode 9 on NiO membrane 8 and can have better ohmic contact to effectively reduce the operating voltage of diode, reduce the use consumption of diode simultaneously, can prolong the life of diode to a certain extent.
Referring to fig. 5, the transparent electrode 9 includes an ITO film disposed on a bottom layer and Ga disposed on the ITO film2O3And (3) a film.
In one embodiment of this example, an ITO film having a thickness of 3nm to 10nm was prepared on NiO film 8 by sputtering, so as to effectively reduce the absorption of deep ultraviolet light. Forming Ga on the ITO film again by sputtering2O3Film of Ga stack2O3The film can effectively improve the transmittance of deep ultraviolet rays, and further improve the brightness of the deep ultraviolet diode. The Ga is2O3The thickness of the film is 50nm-300 nm. Wherein the ITO film is an ohmic contact layer, the Ga2O3The film is a current spreading layer.
In yet another embodiment of this embodiment, the method is as followsPreparing an ITO film on the NiO film 8 by sputtering, wherein the thickness of the ITO film is 3nm-10 nm; forming Ga on the ITO film again by sputtering2O3Film of Ga2O3The thickness of the film is 3nm-10 nm. May be in the Ga2O3Continuously superposing the ITO film on the film, and repeating the steps to obtain the ITO film and Ga2O3The films are stacked alternately to form a transparent electrode 9, and the thickness of the transparent electrode 9 is maintained between 100nm and 300 nm.
Through the two preparation methods of the transparent electrode 9, the brightness of the flip deep ultraviolet diode can be effectively improved, and further, the brightness can be improved by 10% -30%.
The NiO film 8 and the transparent electrode 9 jointly form a P electrode, so that the NiO film has good ohmic contact, can reduce voltage, reduces the using power of the flip deep ultraviolet diode, and can effectively improve the luminous brightness of the diode. The P electrode forms ohmic contact through annealing at 400-600 ℃.
A thick electrode 10 is deposited on the surfaces of the N-electrode 7 and the P-electrode, as shown in fig. 5.
Specifically, a thickened electrode 10 is formed on the surfaces of an N electrode 7 and a P electrode through photoetching and metal evaporation, the thickened electrode 10 also comprises a plurality of metal films, the metal films comprise metal adhesive films formed on the surfaces of the N electrode 7 and the P electrode, the metal adhesive films are formed by evaporation of metal Cr or metal Ni, and the thickness of the metal adhesive films is 1nm-5 nm. And stacking a highly reflective metal film on the metal adhesive film, the highly reflective metal film being formed of one of highly reflective metals Al, Ag, and Rh to achieve an effect of improving luminance by improving reflectivity, the highly reflective metal film having a thickness set between 50nm and 200 nm. The stacking of other metals on the highly reflective metal film may then continue. The brightness of the deep ultraviolet diode is improved and the optical power is improved under the condition of not influencing the ohmic contact characteristic by the arrangement of the thickening electrode 10.
Referring to fig. 6, a passivation layer 11 is formed on the surface of the thickened electrode 10, and the passivation layer 11 is formed of one of silicon oxide, silicon nitride or aluminum oxide. A first space and a second space are respectively formed on the passivation layer 11 by photoetching and etching the passivation layer 11 on the N electrode 7 and the P electrode to provide a space for the PAD electrode 12 arranged on the passivation layer 11.
Referring to fig. 7, photolithography is performed on the bottoms of the first space and the second space, and further, photolithography is performed on the upper surface of the thick electrode 10, and after the photolithography is completed, metal evaporation is performed to form a multi-layer metal film including a multi-metal simple film formed of a plurality of metals, such as Cr, Ni, Ti, Pt, Au, and Sn. The uppermost layer is a metal film formed by metal Au or Sn so as to be used for subsequent packaging eutectic.
The above-mentioned embodiments, objects, technical solutions and advantages of the present application are described in further detail, it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present application, and are not intended to limit the scope of the present application, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present application should be included in the scope of the present application.
Claims (10)
1. A flip-chip deep ultraviolet diode comprises a diode epitaxial surface, and an N electrode and a P electrode which are arranged on the diode epitaxial surface,
the N electrode comprises a metal film formed by copper-aluminum alloy and at least one simple substance film formed by one of Cr, Ni, Au, Ti and Pt, wherein the simple substance film is arranged on the copper-aluminum alloy metal film;
the P electrode comprises a NiO film and a transparent electrode positioned on the NiO film, the transparent electrode comprises an ITO film positioned on the bottom layer and Ga arranged on the ITO film2O3A film;
the N electrode with be provided with the thickening electrode on the P electrode, the thickening electrode includes the high reflection metal film who is formed by one of Al, Ag and Rh.
2. The flip chip deep ultraviolet diode of claim 1,
the ITO film and the Ga2O3The films are connected;
the thickness of the ITO film is 3nm-10nm, and the Ga2O3The thickness of the film is 50nm-300 nm.
3. The flip chip deep ultraviolet diode of claim 1,
the transparent electrode comprises at least two layers of ITO films and at least one layer of Ga2O3A film of the ITO film having a thickness of 3nm to 10nm, the Ga2O3The thickness of the film is 3nm-10 nm;
the ITO film and the Ga2O3The membranes are arranged in a staggered and stacked mode;
the thickness of the transparent electrode is 100nm-300 nm.
4. The flip chip deep ultraviolet diode of claim 1, wherein the weight percentage of copper in the copper aluminum alloy is 1% -5%.
5. The flip chip deep ultraviolet diode of claim 1, wherein the thickness of the NiO is 5nm to 20 nm.
6. A preparation method of a flip deep ultraviolet diode is characterized by comprising the following steps:
evaporating and plating on an N electrode table-board of a semiconductor epitaxial material to form a plurality of layers of metal films, and annealing to form ohmic contact to obtain an N electrode, wherein the metal films comprise a metal film formed by copper-aluminum alloy and at least one layer of elementary substance film formed by one metal of Cr, Ni, Au, Ti and Pt, which is arranged on the copper-aluminum alloy metal film,
forming a layer of Ni metal film on the mesa of the P electrode; forming a NiO film after one of aqua regia, hydrochloric acid or nitric acid is used for treatment; forming a transparent electrode on the NiO film; the process of forming the transparent electrode includes obtaining an ITO film on the bottom layer by sputtering,sputtering and superposing Ga on ITO film2O3Film, and anneal to form ohmic contact to get P electrode;
respectively forming thickened electrodes on the surfaces of the N electrode and the P electrode by evaporation; the thickened electrode comprises a plurality of metal films, and the metal films comprise high-reflection metal films formed by evaporation of one of Al, Ag and Rh.
7. The method of claim 6, wherein the transparent electrode comprises an ITO film with a thickness of 3nm-10nm and Ga with a thickness of 50nm-300nm on the ITO film2O3A film; the ITO film and the Ga2O3The films are arranged in a connecting way.
8. The method for manufacturing a flip-chip deep ultraviolet diode according to claim 6,
the transparent electrode comprises an ITO film with the thickness of 3nm-10nm and Ga with the thickness of 3nm-10nm2O3A film;
the ITO film and the Ga2O3The films are stacked on each other;
the thickness of the transparent electrode is 100nm-300 nm.
9. The method of claim 6, wherein the thickness of the Ni metal film formed on the P electrode mesa is 1nm to 50 nm.
10. The method for preparing a flip chip deep ultraviolet diode as claimed in claim 6, wherein the weight percentage of copper in the copper aluminum alloy is 1% -5%.
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Application publication date: 20220708 |