Disclosure of Invention
In view of this, the present invention provides a light emitting diode and a method for manufacturing the same, which effectively solve the technical problems in the prior art and improve the reliability of the light emitting diode.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a light emitting diode comprising:
a back electrode;
a conductive substrate on one side of the back electrode;
the metal bonding layer is positioned on one side, away from the back electrode, of the conductive substrate;
the ODR reflector layer is positioned on one side, away from the back electrode, of the metal bonding layer and comprises a metal reflecting layer and a dielectric film layer positioned on one side, away from the back electrode, of the metal reflecting layer, wherein the ODR reflector layer comprises a plurality of first through holes or a plurality of second through holes, the first through holes penetrate through the dielectric film layer from one side, away from the back electrode, of the ODR reflector layer, and the second through holes penetrate through the laminated layer of the dielectric film layer and the metal reflecting layer from one side, away from the back electrode, of the ODR reflector layer;
the epitaxial layer is positioned on one side, away from the back electrode, of the ODR reflector layer and comprises a P-type window layer facing one side of the back electrode, the P-type window layer comprises a main body layer and a plurality of first bulges or a plurality of second bulges connected with the main body layer, the first bulges are positioned in the first through holes and form ohmic contact with the metal reflecting layer, and the second bulges are positioned in the second through holes and form ohmic contact with the metal bonding layer;
and the positive electrode is positioned on one side of the epitaxial layer, which is far away from the back electrode.
Optionally, the doping concentration of the first protrusion and the second protrusion is greater than the doping concentration of the body layer.
Optionally, when the ODR mirror layer includes the first through hole, the metal reflective layer is an Au metal reflective layer;
when the ODR reflector layer comprises the second through hole, the metal reflecting layer is an Ag metal reflecting layer, and the metal bonding layer is an Au metal bonding layer.
Optionally, the thickness of the P-type window layer ranges from 0.1 to 11 μm, inclusive.
Optionally, the exposed surface of the epitaxial layer is a roughened surface.
Optionally, the epitaxial layer includes the P-type window layer;
the P-type limiting layer is positioned on one side, away from the back electrode, of the P-type window layer;
the active layer is positioned on one side, away from the back electrode, of the P-type limiting layer;
the N-type limiting layer is positioned on one side, away from the back electrode, of the active layer;
the N-type current expansion layer is positioned on one side, away from the back electrode, of the N-type limiting layer;
the N-type rough layer is positioned on one side, away from the back electrode, of the N-type current expansion layer;
and the N-type ohmic contact layer is positioned on one side, deviating from the back electrode, of the N-type rough layer, and the positive electrode is positioned on one side, deviating from the back electrode, of the N-type ohmic contact layer.
Optionally, the epitaxial layer is an AlGaInP-based epitaxial layer, and the P-type window layer is a P-type GaP window layer;
or, the epitaxial layer is an AlGaAs-based epitaxial layer, the P-type window layer comprises a superposed P-type AlGaAs current expansion layer and a P-type GaP ohmic contact layer, wherein the first protrusion and the second protrusion are formed by the P-type GaP ohmic contact layer, and the main body layer is the P-type AlGaAs current expansion layer.
Correspondingly, the invention also provides a manufacturing method of the light-emitting diode, which comprises the following steps:
sequentially epitaxially growing a buffer layer, a corrosion stop layer and an epitaxial layer on a temporary substrate, wherein a P-type window layer is arranged on one side of the epitaxial layer, which is far away from the temporary substrate;
forming a photoresist layer on one side of the P-type window layer, which is far away from the temporary substrate, wherein the photoresist layers are distributed in a mutually independent point shape;
etching the surface layer of the P-type window layer to form a structure which comprises a main body layer and a plurality of first bulges or a plurality of second bulges, wherein the plurality of first bulges or the plurality of second bulges are connected with the main body layer and correspond to the photoresist layer;
forming an ODR reflector layer on one side, away from the temporary substrate, of the P-type window layer, wherein the ODR reflector layer comprises a dielectric film layer and a metal reflecting layer located on one side, away from the temporary substrate, of the dielectric film layer, when the P-type window layer comprises the first protrusion, the dielectric film layer is formed, then the photoresist layer and redundant dielectric film layer materials on the photoresist layer are stripped through a Lift-off process, and the first protrusion and the metal reflecting layer form ohmic contact; when the P-type window layer comprises the second protrusion, after the dielectric film layer and the metal reflecting layer are formed, stripping the photoresist layer and redundant dielectric film layer materials and redundant metal reflecting layer materials on the photoresist layer by a Lift-off process;
forming a first sub-metal bonding layer on one side, away from the temporary substrate, of the ODR reflector layer, wherein when the P-type window layer comprises the second protrusion, the second protrusion forms ohmic contact with the first sub-metal bonding layer;
bonding the conductive substrate with the second sub-metal bonding layer formed on the surface with the first sub-metal bonding layer to form a metal bonding layer comprising the first sub-metal bonding layer and the second sub-metal bonding layer;
removing the temporary substrate, the buffer layer and the corrosion stop layer;
and forming a positive electrode on one side of the epitaxial layer, which is far away from the conductive substrate, and forming a back electrode on one side of the conductive substrate, which is far away from the epitaxial layer.
Optionally, the doping concentration of the first protrusion and the second protrusion is greater than the doping concentration of the body layer.
Optionally, when the P-type window layer includes the first protrusion, the metal reflective layer is an Au metal reflective layer;
when the P-type window layer comprises the second protrusion, the metal reflecting layer is an Ag metal reflecting layer, and the metal bonding layer is an Au metal bonding layer.
Compared with the prior art, the technical scheme provided by the invention at least has the following advantages:
the invention provides a light-emitting diode and a manufacturing method thereof, wherein an ODR reflector layer comprises a metal reflecting layer and a dielectric film layer positioned on one side of the metal reflecting layer, which is far away from a back electrode, wherein the ODR reflector layer comprises a plurality of first through holes or a plurality of second through holes, the first through holes penetrate through the dielectric film layer from the side, which is far away from the back electrode, of the ODR reflector layer, and the second through holes penetrate through the lamination of the dielectric film layer and the metal reflecting layer from the side, which is far away from the back electrode, of the ODR reflector layer; the P-type window layer comprises a main body layer and a plurality of first bulges or a plurality of second bulges connected with the main body layer, the first bulges are positioned in the first through holes and form ohmic contact with the metal reflecting layer, and the second bulges are positioned in the second through holes and form ohmic contact with the metal bonding layer. And when the light-emitting diode is manufactured, the self-alignment of the protrusion of the P-type window layer and the ODR reflector layer is realized by adopting a Lift-off process. Therefore, the P-type window layer provided by the invention respectively and correspondingly realizes ohmic contact with the metal reflecting layer or the metal bonding layer through the first protrusion or the second protrusion, the condition that metal faults in the through hole are generated when metal materials are filled in the through hole to realize ohmic contact is avoided, the high reliability of the light-emitting diode is ensured, and the problems of high preparation cost and complex process flow caused by filling the metal materials can be solved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 invention.
As mentioned in the background, as the application of LED (Light Emitting Diode) is gradually expanded, the market demand for LED performance is higher and higher. Therefore, the reliability of the light emitting diode is to be improved.
Therefore, the embodiment of the invention provides the light-emitting diode and the manufacturing method thereof, which effectively solve the technical problems in the prior art and improve the reliability of the light-emitting diode.
To achieve the above object, the technical solutions provided by the embodiments of the present invention are described in detail below with reference to fig. 1 to 5.
As shown in fig. 1, which is a schematic structural diagram of a light emitting diode according to an embodiment of the present invention, the light emitting diode includes:
a back electrode 100.
A conductive substrate 200 at one side of the back electrode 100.
A metal bonding layer 300 on a side of the conductive substrate 200 facing away from the back electrode 100.
The ODR mirror layer 400 is located on a side of the metal bonding layer 300 away from the back electrode 100, where the ODR mirror layer 400 includes a metal reflective layer 410 and a dielectric film layer 420 located on a side of the metal reflective layer 410 away from the back electrode, and the ODR mirror layer 400 includes a plurality of first through holes penetrating through the dielectric film layer 420 from a side of the ODR mirror layer 400 away from the back electrode 100.
The epitaxial layer 500 is located on a side of the ODR mirror layer 400 away from the back electrode 100, the epitaxial layer 500 includes a P-type window layer 510 facing the back electrode 100, the P-type window layer 510 includes a main body layer 511 and a plurality of first protrusions 512 connected to the main body layer 511, and the first protrusions 512 are located in the first through holes and form ohmic contact with the metal reflective layer 410.
And the positive electrode 600 is positioned at the side of the epitaxial layer 500, which is far away from the back electrode 100, wherein the occupied area of the positive electrode 600 is smaller than the area of the surface of the side of the epitaxial layer 500, which is far away from the back electrode 100.
Referring to fig. 1, the P-type window layer 510 provided by the embodiment of the invention may form an ohmic contact with the metal reflective layer 410, that is, the depth of the first through hole is the same as the height of the first protrusion 512, that is, the height of the first protrusion 512 is the same as the thickness of the dielectric film layer 420; and, when the ODR mirror layer 400 provided by the embodiment of the present invention includes the first through hole, the metal reflective layer 410 may be an Au metal reflective layer.
Or, the P-type window layer provided by the embodiment of the present invention may also form an ohmic contact with the metal bonding layer, that is, the depth of the second through hole is the same as the height of the second protrusion, that is, the height of the second protrusion is the same as the stacking thickness of the dielectric film layer and the metal reflective layer; and when the ODR mirror layer provided in the embodiment of the present invention includes the second through hole, the metal reflective layer is an Ag metal reflective layer, and the metal bonding layer is an Au metal bonding layer. Specifically, as shown in fig. 2, a schematic structural diagram of a light emitting diode provided in an embodiment of the present invention is shown, where the light emitting diode includes:
a back electrode 100.
A conductive substrate 200 at one side of the back electrode 100.
A metal bonding layer 300 on a side of the conductive substrate 200 facing away from the back electrode 100.
The ODR mirror layer 400 is located on a side of the metal bonding layer 300 facing away from the back electrode 100, where the ODR mirror layer 400 includes a metal reflective layer 410 and a dielectric film layer 420 located on a side of the metal reflective layer 410 facing away from the back electrode, and the ODR mirror layer 400 includes a plurality of second through holes penetrating through a stack of the dielectric film layer 420 and the metal reflective layer 410 from a side of the ODR mirror layer 400 facing away from the back electrode 100.
The epitaxial layer 500 is located on the side of the ODR mirror layer 400 departing from the back electrode 100, the epitaxial layer 500 includes a P-type window layer 510 facing the side of the back electrode 100, the P-type window layer includes a main body layer 511 and a plurality of second protrusions 513 connected to the main body layer, and the second protrusions 513 are located in the second through holes and form ohmic contact with the metal bonding layer 300.
And a positive electrode 600 located on a side of the epitaxial layer 500 facing away from the back electrode 100.
As can be seen from the above, in the technical solution provided in the embodiment of the present invention, the ODR mirror layer includes a metal reflective layer and a dielectric film layer located on a side of the metal reflective layer away from the back electrode, where the ODR mirror layer includes a plurality of first through holes or a plurality of second through holes, the first through holes penetrate through the dielectric film layer from the side of the ODR mirror layer away from the back electrode, and the second through holes penetrate through a stack of the dielectric film layer and the metal reflective layer from the side of the ODR mirror layer away from the back electrode; the P-type window layer comprises a main body layer and a plurality of first bulges or a plurality of second bulges connected with the main body layer, the first bulges are positioned in the first through holes and form ohmic contact with the metal reflecting layer, and the second bulges are positioned in the second through holes and form ohmic contact with the metal bonding layer. Therefore, the P-type window layer provided by the embodiment of the invention respectively and correspondingly realizes ohmic contact with the metal reflecting layer or the metal bonding layer through the first protrusion or the second protrusion, thereby avoiding the occurrence of metal faults in the through hole when the metal material is filled in the through hole to realize ohmic contact, ensuring high reliability of the light-emitting diode, and simultaneously solving the problems of high preparation cost and complex process flow caused by filling the metal material.
In an embodiment of the invention, the doping concentration of the first protrusion and the second protrusion provided by the invention is greater than the doping concentration of the body layer. Wherein the doping concentration of the first and second protrusions may be greater than or equal to 1E19/cm3And of the body layerThe doping concentration may be greater than or equal to 1E18/cm3. Optionally, the thickness of the P-type window layer provided by the embodiment of the present invention may be in a range of 0.1 to 11 μm, inclusive.
It can be understood that, in the P-type window layer provided by the embodiment of the invention, the high-doping concentration region is formed only at the first protrusion and the second protrusion, and the low-doping concentration region is formed at the body layer, so that the protrusion and the metal structure are ensured to form good ohmic contact, the problem of light absorption on the surface of the high-doping P-type window layer is avoided, and the light extraction efficiency of the light emitting diode is improved.
In an embodiment of the invention, the exposed surface of the epitaxial layer provided by the invention is a roughened surface. As shown in fig. 3, a schematic structural diagram of another light emitting diode according to an embodiment of the present invention is provided, wherein an exposed surface of the epitaxial layer 500 is a roughened surface, so as to further ensure high light extraction efficiency of the light emitting diode.
Fig. 4 is a schematic structural diagram of another light emitting diode according to an embodiment of the present invention, wherein the epitaxial layer 500 includes the P-type window layer 510.
And the P-type limiting layer 520 is positioned on the side, facing away from the back electrode 100, of the P-type window layer 510.
And the active layer 530 is positioned on the side, away from the back electrode 100, of the P-type confinement layer 520, and the active layer 530 is a multi-quantum well active layer.
And an N-type confinement layer 540 on a side of the active layer 530 facing away from the back electrode 100.
An N-type current spreading layer 550 located on a side of the N-type confinement layer 540 facing away from the back electrode 100.
An N-type roughened layer 560 on a side of the N-type current spreading layer 550 facing away from the back electrode 100.
And an N-type ohmic contact layer 570 on a side of the N-type roughened layer 560 facing away from the back electrode 100, where the N-type ohmic contact layer 570 may be an N-type GaAs ohmic contact layer, and the positive electrode 600 is located on a side of the N-type ohmic contact layer 570 facing away from the back electrode 100.
In an embodiment of the invention, the epitaxial layer provided by the invention may be an AlGaInP-based epitaxial layer, wherein the P-type confinement layer, the N-type current spreading layer and the N-type roughened layer are all structural layers made of AlGaInP materials, and components in each structural layer made of AlGaInP materials may be specifically adjusted according to practical applications. The P-type window layer is a P-type GaP window layer, namely the first protrusion, the second protrusion and the main body layer are all made of P-type GaP materials; the thickness of the P-type window layer can be 0.1-10 μm inclusive, and specifically can be 1-3 μm inclusive.
Alternatively, the epitaxial layer provided in the embodiment of the present invention may also be an AlGaAs-based epitaxial layer, where the P-type confinement layer, the N-type current spreading layer, and the N-type coarse layer are all structural layers made of AlGaAs material, and components in each structural layer made of AlGaAs material may be specifically adjusted according to actual applications. And the P-type window layer comprises a superposed P-type AlGaAs current expansion layer and a P-type GaP ohmic contact layer, wherein the first protrusion and the second protrusion are formed by the P-type GaP ohmic contact layer, and the main body layer is the P-type AlGaAs current expansion layer. Optionally, the thickness of the P-type AlGaAs current spreading layer may range from 0.9 to 9.9 μm, inclusive, and may specifically be 3 μm; the thickness of the P-type GaP ohmic contact layer may range from 0.1 to 1 μm, inclusive, and may specifically be 0.2 μm.
Correspondingly, the embodiment of the invention also provides a manufacturing method of the light-emitting diode. As shown in fig. 5, a flowchart of a method for manufacturing a light emitting diode according to an embodiment of the present invention is provided, where the method includes:
s1, sequentially epitaxially growing a buffer layer, a corrosion stop layer and an epitaxial layer on the temporary substrate, wherein a P-type window layer is arranged on one side, away from the temporary substrate, of the epitaxial layer.
In an embodiment of the invention, the temporary substrate provided by the invention may be a GaAs temporary substrate, the buffer layer may be an N-type GaAs buffer layer, and the etch stop layer may be an N-type GaInP etch stop layer. The epitaxial layer may be an AlGaInP-based epitaxial layer or an AlGaAs-based epitaxial layer, and the present invention is not particularly limited thereto.
And S2, forming a photoresist layer on one side of the P-type window layer, which is far away from the temporary substrate, wherein the photoresist layers are distributed in a mutually independent point shape.
It can be understood that the mutually independent point-like photoresist layers are photoresist patterns for defining a plurality of first protrusions or a plurality of second protrusions.
S3, etching the surface layer of the P-type window layer to form a structure which comprises a main body layer and a plurality of first bulges or a plurality of second bulges, wherein the first bulges or the second bulges are connected with the main body layer and correspond to the photoresist layer.
It can be understood that the photoresist layer is used as a mask, and a material with a certain thickness, which is not covered by the P-type window layer, of the photoresist layer is removed through a dry etching process or a wet etching process to form the body layer and the first protrusion or the second protrusion.
S4, forming an ODR reflector layer on one side, away from the temporary substrate, of the P-type window layer, wherein the ODR reflector layer comprises a dielectric film layer and a metal reflecting layer located on one side, away from the temporary substrate, of the dielectric film layer, and when the P-type window layer comprises the first protrusion, after the dielectric film layer is formed, the photoresist layer and redundant dielectric film layer materials on the photoresist layer are stripped through a Lift-off process, and the first protrusion and the metal reflecting layer form ohmic contact; and when the P-type window layer comprises the second protrusion, after the dielectric film layer and the metal reflecting layer are formed, stripping the photoresist layer and redundant dielectric film layer materials and redundant metal reflecting layer materials on the photoresist layer by a Lift-off process.
In an embodiment of the invention, the thickness of the dielectric film provided by the invention can be obtained according to (2k +1) λ/4n, where k is 0 or a positive integer, λ is the light-emitting wavelength of the light-emitting diode, and n is the refractive index of the material of the dielectric film. Wherein the dielectric film layer may be MgF2The present invention is not particularly limited.
S5, forming a first sub-metal bonding layer on the side, away from the temporary substrate, of the ODR reflector layer, wherein when the P-type window layer comprises the second protrusion, the second protrusion forms ohmic contact with the first sub-metal bonding layer.
In an embodiment of the invention, the metal reflective layer and the first sub-metal bonding layer provided by the invention can be formed by an evaporation process. Meanwhile, an annealing process is adopted to enable the metal reflecting layer to form ohmic contact with the first protrusion, or the annealing process is adopted to enable the first sub-metal bonding layer to form ohmic contact with the second protrusion.
And S6, bonding the conductive substrate with the second sub-metal bonding layer on the surface with the first sub-metal bonding layer to form a metal bonding layer comprising the first sub-metal bonding layer and the second sub-metal bonding layer.
In an embodiment of the present invention, the conductive substrate provided in the present invention may be a P-type low-resistance silicon wafer, and the present invention is not particularly limited.
And S7, removing the temporary substrate, the buffer layer and the corrosion stop layer.
In an embodiment of the present invention, the epitaxial layer provided by the present invention may include an N-type ohmic contact layer. After the corrosion stop layer is removed, the N-type ohmic contact layer can be subjected to patterning treatment to form an N-type ohmic contact pattern, and then an N-type electrode, namely a positive electrode, is prepared through subsequent photoetching, evaporation, stripping and annealing processes.
S8, forming a positive electrode on the side, away from the conductive substrate, of the epitaxial layer, and forming a back electrode on the side, away from the epitaxial layer, of the conductive substrate.
Optionally, after the positive electrode is formed on the conductive substrate, if the sheet source is required to be split, the reserved cutting channel can be etched to the P-type window layer through a photoetching or dry etching process; then, the exposed surface of the epitaxial layer can be further subjected to roughening treatment to form a roughened surface; then, grinding and thinning the conductive substrate, and preparing a P-type electrode, namely preparing a back electrode, by a lattice evaporation annealing process; finally, the wafer source can be divided into independent light emitting diodes through tangent, back cut and splitting procedures, which are the same as the prior art, so redundant description is not needed in the invention.
In an embodiment of the invention, the doping concentration of the first protrusion and the second protrusion provided by the invention is greater than the doping concentration of the body layer.
And when the P-type window layer provided by the embodiment of the invention comprises the first protrusion, the metal reflecting layer is an Au metal reflecting layer. When the P-type window layer provided by the embodiment of the invention comprises the second protrusion, the metal reflecting layer is an Ag metal reflecting layer, and the metal bonding layer is an Au metal bonding layer.
The embodiment of the invention provides a light-emitting diode and a manufacturing method thereof, wherein an ODR reflector layer comprises a metal reflecting layer and a dielectric film layer positioned on one side of the metal reflecting layer, which is far away from a back electrode, wherein the ODR reflector layer comprises a plurality of first through holes or a plurality of second through holes, the first through holes penetrate through the dielectric film layer from the side, which is far away from the back electrode, of the ODR reflector layer, and the second through holes penetrate through a lamination of the dielectric film layer and the metal reflecting layer from the side, which is far away from the back electrode, of the ODR reflector layer; the P-type window layer comprises a main body layer and a plurality of first bulges or a plurality of second bulges connected with the main body layer, the first bulges are positioned in the first through holes and form ohmic contact with the metal reflecting layer, and the second bulges are positioned in the second through holes and form ohmic contact with the metal bonding layer. And when the embodiment of the invention is used for manufacturing the light-emitting diode, the Lift-off process is adopted to realize the self-alignment of the bulge of the P-type window layer and the ODR reflector layer. Therefore, the P-type window layer provided by the embodiment of the invention respectively and correspondingly realizes ohmic contact with the metal reflecting layer or the metal bonding layer through the first protrusion or the second protrusion, thereby avoiding the occurrence of metal faults in the through hole when the metal material is filled in the through hole to realize ohmic contact, ensuring high reliability of the light-emitting diode, and simultaneously solving the problems of high preparation cost and complex process flow caused by filling the metal material.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.