CN113206179B - Light emitting diode and method of manufacturing the same - Google Patents
Light emitting diode and method of manufacturing the same Download PDFInfo
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- CN113206179B CN113206179B CN202110351783.8A CN202110351783A CN113206179B CN 113206179 B CN113206179 B CN 113206179B CN 202110351783 A CN202110351783 A CN 202110351783A CN 113206179 B CN113206179 B CN 113206179B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
- H01L33/38—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape
Abstract
The application discloses a light emitting diode and a manufacturing method thereof, the light emitting diode includes: a first semiconductor layer; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer; the insulating medium layer is positioned on the second semiconductor layer; and a plurality of ohmic contact structures covering part of the surface of the insulating medium layer, wherein each ohmic contact structure extends into the second semiconductor layer through the surface of the insulating medium layer, and each ohmic contact structure and the second semiconductor layer form ohmic contact. According to the light-emitting diode, the ohmic contact structure and the ohmic contact surface of the second semiconductor layer longitudinally extend to the inside of the second semiconductor layer, so that the area of the ohmic contact surface is increased, the on-resistance of the light-emitting diode is reduced, and the purposes of reducing voltage and reducing energy consumption are achieved.
Description
Technical Field
The present disclosure relates to the field of semiconductor manufacturing technologies, and more particularly, to a light emitting diode and a method for manufacturing the same.
Background
The reversed polarity Light Emitting Diode (LED) has great demand in domestic market, has wide application range, and is applied to daily remote controllers, cameras in markets, security monitoring, medical appliances and automatic card swiping systems of highways.
The application requirements of the reverse polarity light emitting diode include that the reverse polarity light emitting diode has larger luminous power, and the manufacturing process and the process of the reverse polarity light emitting diode are relatively complicated at present to ensure the larger luminous power. Multiple photolithography and thin film deposition techniques result in much more process steps than other led fabrication processes, which increases uncertainty in reducing reliability and overall yield. If the intermediate steps can be simplified or one structure can be used for achieving the effects of various structures, the cost can be reduced, and the adverse effect of uncertain factors on the whole process flow can be reduced.
Therefore, it is desirable to further optimize the structure of the light emitting diode and the method of manufacturing the same so that the process steps can be optimized and the cost can be reduced.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a light emitting diode and a method for manufacturing the same, so as to achieve the purposes of optimizing the process steps and reducing the cost.
According to an aspect of an embodiment of the present invention, there is provided a light emitting diode including a first semiconductor layer; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer; the insulating medium layer is positioned on the second semiconductor layer; and the ohmic contact structures cover part of the surface of the insulating medium layer, each ohmic contact structure extends into the second semiconductor layer through the surface of the insulating medium layer, and each ohmic contact structure and the second semiconductor layer form ohmic contact.
Optionally, the plurality of ohmic contact structures are arranged according to a preset rule.
Optionally, the arranging according to the preset rule includes arranging according to an equal interval.
Optionally, each ohmic contact structure comprises a first part located on the insulating medium layer and a second part located in the insulating medium layer and the second semiconductor layer, and for each ohmic contact structure, the first part covers the contact surface of the second part and the insulating medium layer.
Optionally, the first portion has a thickness of
Optionally, the insulating medium layer acts as a current confinement layer to confine current to each of the ohmic contact structures.
Optionally, a cross-sectional shape of the second portion of each ohmic contact structure is a shape that is wide at the top and narrow at the bottom in a thickness direction of the second semiconductor layer.
Optionally, a cross-sectional shape of the second portion of each ohmic contact structure along a thickness direction of the second semiconductor layer is a shape having the same width from top to bottom.
Optionally, the second part of the ohmic contact structure is 3-5um deep.
Optionally, the cross-sectional shape of the ohmic contact structure is at least one of circular, elliptical and polygonal along a direction parallel to the surface of the insulating medium layer.
Optionally, the cross-sectional shape of the ohmic contact structure is a square along a direction parallel to the surface of the insulating medium layer, and the side length of the square is 4-7 um.
Optionally, a cross-sectional area of the first portion of the ohmic contact structure in a direction parallel to the surface of the insulating medium layer accounts for 3% to 9% of an area of a light emitting region of the light emitting diode.
Optionally, the insulating medium layer and the second semiconductor layer form a single-layer bragg reflector, and a refractive index of the insulating medium layer is smaller than a refractive index of the second semiconductor layer.
Optionally, the thickness of the insulating dielectric layer is 100 to 200 nm.
Optionally, the insulating dielectric layer is obtained by oxidizing a contact layer.
Optionally, the material of the contact layer and the second semiconductor layer includes at least one Al-containing compound of AlGaAs, AlGaInP and AlInP, wherein the Al composition of the Al-containing compound of the contact layer is greater than the Al composition of the Al-containing compound of the second semiconductor layer.
Optionally, the aluminum-containing compound is Al x Ga 1-x As, Al in the second semiconductor layer x Ga 1-x In As, x is 0.1-0.3, and Al in the contact layer x Ga 1-x In As, x is between 1 and 0.8.
Optionally, the aluminum-containing compound is Al x Ga 1-x InP, Al in the second semiconductor layer x Ga 1-x In InP, x is 0.1-0.2, and Al in the contact layer x Ga 1-x In InP, x is 1-0.7.
Optionally, the second semiconductor layer comprises: a blocking layer on the active layer; a space layer on the barrier layer; and a window layer on the space layer, wherein each of the ohmic contact structures extends into the window layer.
Optionally, the thickness of the window layer is 6 to 8 um.
Optionally, the semiconductor device further comprises a reflective layer covering the insulating medium layer and the plurality of ohmic contact structures.
Optionally, the reflective layer is an Ag mirror reflective layer or an Au mirror reflective layer.
Optionally, the method further comprises: a permanent substrate on the reflective layer; and a bonding layer between the permanent substrate and the reflective layer to fixedly connect the permanent substrate and the reflective layer.
Optionally, the method further comprises: the first electrode is positioned on the surface of the first semiconductor layer, which is far away from the active layer; and a second electrode located on a surface of the permanent substrate remote from the bonding layer.
According to another aspect of the embodiments of the present invention, there is provided a method of manufacturing a light emitting diode, including: forming a first semiconductor layer on a growth substrate; forming an active layer on the first semiconductor layer; forming a second semiconductor layer on the active layer; forming an insulating medium layer on the second semiconductor layer; and forming a plurality of ohmic contact structures, covering part of the surface of the insulating medium layer, wherein each ohmic contact structure extends into the second semiconductor layer through the surface of the insulating medium layer, and each ohmic contact structure and the second semiconductor layer form ohmic contact.
Optionally, the step of forming the insulating dielectric layer includes: forming a contact layer on the second semiconductor layer; and oxidizing the contact layer to form an insulating dielectric layer, wherein the insulating dielectric layer acts as a current confinement layer to confine current to each of the ohmic contact structures.
Optionally, the insulating medium layer and the second semiconductor layer form a single-layer bragg reflector, and a refractive index of the insulating medium layer is smaller than a refractive index of the second semiconductor layer.
Optionally, the material of the contact layer and the second semiconductor layer includes at least one Al-containing compound of AlGaAs, AlGaInP and AlInP, wherein the Al composition of the Al-containing compound of the contact layer is greater than the Al composition of the Al-containing compound of the second semiconductor layer.
Optionally, the aluminum-containing compound is Al x Ga 1-x As, Al in the second semiconductor layer x Ga 1-x In As, x is 0.1-0.3, and Al in the contact layer x Ga 1-x In As, x is between 1 and 0.8.
Optionally, the aluminum-containing compound is Al x Ga 1-x InP, Al in the second semiconductor layer x Ga 1-x In InP, x is 0.1-0.2, and Al in the contact layer x Ga 1-x In InP, x is 1-0.7.
Optionally, the step of oxidizing the contact layer comprises steam oxidation.
Optionally, the step of forming the second semiconductor layer comprises: forming a barrier layer on the active layer; forming a space layer on the barrier layer; and forming a window layer on the space layer, wherein each of the ohmic contact structures extends into the window layer.
Optionally, the step of forming a plurality of ohmic contact structures comprises: forming a first mask on the insulating medium layer, wherein the first mask is provided with a first through hole; etching the insulating medium layer and the window layer through the first through hole to form a contact hole; and filling a conductive material in the contact hole to form the ohmic contact structure.
Optionally, before filling the conductive material, the step of forming a plurality of ohmic contact structures further comprises: removing the first mask; and forming a second mask on the insulating medium layer, wherein the second mask is provided with a second through hole, the position of the second through hole corresponds to the first through hole, the aperture of the second through hole is larger than that of the first through hole, the conductive material is further filled in the second through hole, the conductive material filled in the second through hole is positioned on the insulating medium layer and serves as a first part of the ohmic contact structure, the conductive material filled in the contact hole is positioned in the insulating medium layer and the window layer and serves as a second part of the ohmic contact structure, and for each ohmic contact structure, the first part covers the contact surface of the second part and the window layer.
Optionally, the difference between the diameters of the second through hole and the first through hole is 2-3 um.
Optionally, the plurality of ohmic contact structures are arranged according to a preset rule.
Optionally, the arranging according to the preset rule includes arranging according to an equal interval.
Optionally, the first portion of the ohmic contact structure has a thickness of
Optionally, the second part of the ohmic contact structure is 3-5um deep.
Optionally, the cross-sectional shape of the ohmic contact structure is at least one of circular, elliptical and polygonal along a direction parallel to the surface of the insulating medium layer.
Optionally, the cross section of the ohmic contact structure is square along a direction parallel to the surface of the insulating medium layer, and the side length of the square is 4-7 um.
Optionally, a cross-sectional area of the first portion of the ohmic contact structure in a direction parallel to the surface of the insulating medium layer accounts for 3% to 9% of an area of a light emitting region of the light emitting diode.
Optionally, the method further comprises: and annealing the second semiconductor layer and the ohmic contact structure.
Optionally, the thickness of the insulating dielectric layer is 100 to 200 nm.
Optionally, the thickness of the window layer is 6 to 8 um.
Optionally, a cross-sectional shape of the second portion of each ohmic contact structure is a shape that is wide at the top and narrow at the bottom in a thickness direction of the second semiconductor layer.
Optionally, a cross-sectional shape of the second portion of each ohmic contact structure along a thickness direction of the second semiconductor layer is a shape having the same width up and down.
Optionally, forming a reflective layer covering the insulating medium layer and the plurality of ohmic contact structures is further included.
Optionally, the reflective layer is an Ag mirror reflective layer or an Au mirror reflective layer.
Optionally, the method further comprises: forming a first bonding layer on the reflective layer; forming a second bonding layer on the permanent substrate; bonding the first bonding layer and the second bonding layer; and removing the growth substrate.
Optionally, the method further comprises: forming a first electrode on the surface of the first semiconductor layer far away from the active layer; and forming a second electrode on a surface of the permanent substrate remote from the bonding layer.
According to the light emitting diode and the manufacturing method thereof provided by the embodiment of the invention, the ohmic contact structure and the ohmic contact surface of the second semiconductor layer longitudinally extend to the inside of the second semiconductor layer, so that the area of the ohmic contact surface is increased, the on-resistance of the light emitting diode is reduced, and the purposes of reducing voltage and reducing energy consumption are achieved.
Each ohmic contact structure comprises a first part positioned on the insulating medium layer and a second part positioned in the insulating medium layer and the second semiconductor layer, and for each ohmic contact structure, the first part covers the contact surface of the second part and the insulating medium layer, so that the ohmic contact surface is shielded by the first part, and in the subsequent process, other substances cannot be filled in the ohmic contact surface, and the ohmic contact performance is ensured.
An insulating medium layer is formed through an oxidation step, the insulating medium layer not only can be used as a current limiting layer to limit current in an ohmic contact structure, but also can form a single-layer Bragg reflector with a second semiconductor layer below the insulating medium layer, and particularly, a window layer in the second semiconductor layer not only is used as an ohmic contact layer, but also is used for forming the single-layer Bragg reflector, so that the effect of one-layer multi-purpose is achieved, the process steps are simplified, and the cost is reduced.
The reflecting layer is formed on the single-layer Bragg reflector and combined with the Bragg reflector, so that the reflecting efficiency is further improved, and the light-emitting intensity of the light-emitting surface is improved.
In addition, the ohmic contact surface longitudinally extends into the second semiconductor layer, so that the two-dimensional ohmic contact is converted into the three-dimensional ohmic contact, and the ohmic contact area of the three-dimensional ohmic contact is far higher than that of the two-dimensional ohmic contact, so that the plane area of the light reflecting area occupied by the three-dimensional ohmic contact structure can be properly reduced on the premise of increasing the total area of the ohmic contact, and the light intensity of the light emitting diode can be increased while the voltage is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description only relate to some embodiments of the present application and are not limiting on the present application.
Fig. 1 is a schematic view showing a structure of a light emitting diode in the related art.
Fig. 2 to 12 are structural diagrams illustrating a method of manufacturing a light emitting diode according to an embodiment of the present invention at some stages.
FIG. 13 is a graph showing the relationship between the Al composition and the refractive index of an AlGaAs material.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. Like elements are denoted by like reference numerals throughout the various figures. For purposes of clarity, the various features in the drawings are not drawn to scale. In addition, certain well known components may not be shown. For simplicity, the semiconductor structure obtained after several steps can be described in one figure.
It will be understood that when a layer or region is referred to as being "on" or "over" another layer or region, it can be directly on the other layer or region or intervening layers or regions may also be present in the structure of the device. And, if the device is turned over, one layer or region may be "under" or "beneath" another layer or region.
If for the purpose of describing the situation directly on another layer, another area, the expressions "directly on … …" or "on … … and adjacent thereto" will be used herein.
In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
The present invention may be embodied in various forms, some examples of which are described below.
Fig. 1 shows a schematic structure diagram of a light emitting diode in the related art.
As shown in fig. 1, in the related art, the reverse-polarity vertical type light emitting diode includes: the semiconductor device includes a first semiconductor layer 101, an active layer 102, a second semiconductor layer 103, a contact layer 104, an insulating layer 105, a reflective layer 106, a first bonding layer 107, a second bonding layer 108, a substrate 109, an ohmic contact structure 110, a first electrode 121, and a second electrode 122.
Wherein, along the direction from the second electrode 122 to the first electrode 121, the first semiconductor layer 101, the active layer 102, the second semiconductor layer 103, the contact layer 104, the insulating layer 105, the reflective layer 106, the first bonding layer 107, the second bonding layer 108, and the substrate 109 are sequentially stacked. The second electrode 122 is in contact with the first semiconductor layer 101, and the first electrode 121 is in contact with the substrate 109. The ohmic contact structure 110 penetrates the insulating layer 105 and is in contact with the reflective layer 106 and the contact layer 104, respectively, and the ohmic contact structure 110 forms ohmic contact with the contact layer 104.
In the related art, light emitted from the active layer 102 is emitted through the first semiconductor layer 101, and the reflective layer 106 serves to reflect the light, so that more light is emitted from the first semiconductor layer 101. The ohmic contact structure 110 is located between the active layer 102 and the reflective layer 106, and blocks a part of the light reflected path. In order to reduce the on-resistance of the light emitting diode, the ohmic contact structure 110 needs to form an ohmic contact with the contact layer 104, and the larger the area of the ohmic contact formed on the surface of the contact layer 104 is, the smaller the on-resistance is, the lower the voltage of the light emitting diode is, thereby reducing power consumption. However, the larger the area of the ohmic contact formed on the surface of the contact layer 104 is, the larger the light reflecting area occupied by the ohmic contact structure 110 is, which affects the light output amount.
In the related art, the insulating layer 105 serves to limit the current flowing through each ohmic contact structure 110, and the insulating layer 105 is generally MgF 2 Or SiO 2 The insulating material with the equal refractive index lower than 1.7 is formed and is different from the material of the contact layer 104, so that the contact layer 104 and the insulating layer 105 need to be manufactured separately, and the process flow is more.
In view of the above technical problems, embodiments of the present invention provide a light emitting diode and a method for manufacturing the same, which are suitable for a reverse polarity light emitting diode, and will be described in detail with reference to fig. 2 to 12.
As shown in fig. 2, a first semiconductor layer 210, an active layer (MQW multi-quantum well structure) 220, a barrier layer (clipping) 231, a spacer layer (Space)232, a Window layer (Window)233, and a contact layer 20 are sequentially stacked and formed on a growth substrate 10, wherein the barrier layer 231, the spacer layer 232, and the Window layer 233 constitute a second semiconductor layer 230.
In the present embodiment, the material of the growth substrate 10 is GaAs. The material of the first semiconductor layer 210, the active layer 220, the barrier layer 231, the spacer layer 232, the window layer 233, and the contact layer 20 is Al-containing compound such as AlGaAs, AlGaInP, and AlInP. The doping types of the first semiconductor layer 210 and the second semiconductor layer 230 and the contact layer 20 are opposite, for example, the doping type of the first semiconductor layer 210 is N type, the doping types of the second semiconductor layer 230 and the contact layer 20 are P type, or the doping type of the first semiconductor layer 210 is P type, and the doping types of the second semiconductor layer 230 and the contact layer 20 are N type.
In the present embodiment, the thickness D of the window layer 233 is 6 to 8 um. The Al composition of the aluminum-containing compound of the contact layer 20 is greater than that of the second semiconductor layer 230 (the barrier layer 231, the space layer 232, and the window layer 233). In some embodiments, when the aluminum-containing compound is Al x Ga 1-x As, Al of the second semiconductor layer 230 x Ga 1-x Al component x of As is 0.1-0.3, Al of contact layer 20 x Ga 1-x The Al component x of As is between 0.8 and 1, wherein the lower the Al component, the larger the refractive index, As shown in FIG. 13. In other embodiments, when the aluminum-containing compound is Al x Ga 1- x In case of InP, Al of the second semiconductor layer 230 x Ga 1-x The value of the Al component x of the InP is between 0.1 and 0.2, and the Al of the contact layer 20 x Ga 1-x The value of the Al component x of the InP is between 1 and 0.7. However, the embodiments of the present invention are not limited thereto, and those skilled in the art may make other arrangements of the materials, the compositions, and the doping types of the growth substrate 10, the first semiconductor layer 210, the active layer 220, the second semiconductor layer 230, and the contact layer 20 as needed.
Further, the contact layer 20 is oxidized to form an insulating dielectric layer 234, as shown in fig. 3.
In this step, the contact layer 20 is oxidized, for example, by a high temperature steam oxidation process at a temperature of 300 to 800 ℃, and the insulating dielectric layer 234 is formed to have a low refractive index of 1.6 to 1.8.
In the present embodiment, the insulating dielectric layer 234 has a thickness of 100 to 200nm, and the insulating dielectric layer 234 serves as a current confinement layer for confining current from the second electrode formed in a subsequent step into the ohmic contact structure.
In the present embodiment, the refractive index of the insulating medium layer 234 is smaller than that of the second semiconductor layer, and the insulating medium layer 234 and the second semiconductor layer constitute a single-layer bragg reflector.
However, the embodiments of the present invention are not limited thereto, and those skilled in the art may perform other arrangements for the oxidation process as needed.
Further, a first mask 30 is formed on the insulating dielectric layer 234, as shown in fig. 4.
In this step, for example, a photoresist is first coated on the surface of the insulating dielectric layer 234, and then a first mask 30 having a first through hole 31 is formed by using a photolithography process.
In the present embodiment, the aperture of the first through hole 31 is d1, and the shape of the first through hole 31 is circular, elliptical, or polygonal. In some embodiments, the first through hole 31 is square, and the side of the square is 4-7 um. Of course, those skilled in the art can make other arrangements to the shape and size of the first through hole 31 as required.
Further, the insulating dielectric layer 234 and the window layer 233 are etched through the first via hole 31 to form a contact hole 235, as shown in fig. 5.
In this step, portions of the insulating dielectric layer 234 and the window layer 233 are sequentially removed, for example, by a dry etching process, and the shape of the first via 31 is transferred to the contact hole 235 by controlling the time such that the etching stops inside the window layer 233.
In the present embodiment, the depth of the contact hole 235 is 3-5 um. On the surface of the insulating medium layer 234, the cross-sectional area of the contact hole 235 along the direction parallel to the surface of the insulating medium layer 234 accounts for 3% -9% of the area of the light-emitting area of the whole light-emitting diode. Of course, other arrangements of the depth of the contact hole 235 and the relative area ratio of the contact hole 235 to the led may be made by those skilled in the art.
Further, the first mask is removed and a second mask 40 is formed on the insulating dielectric layer 234, as shown in fig. 6.
In this step, for example, the first mask is removed by ashing, and then a second mask 40 is formed on the insulating dielectric layer 234 by photolithography or the like, wherein the second mask 40 has a second via hole 41, the position of the second via hole 41 corresponds to the position of the first via hole 31 or the contact hole 235, and the aperture d2 of the second via hole 41 is larger than the aperture d1 of the first via hole 31. In the present embodiment, aperture d2 is 2 to 3um larger than aperture d 1. Of course, those skilled in the art may make other settings for the difference between the hole diameters of the first through hole 31 and the second through hole 41 as needed.
Further, a conductive material is filled in the contact hole 235 and the second via hole 41 to form an ohmic contact structure 240, as shown in fig. 7.
In this step, a conductive material is filled in the contact hole 235 and the second via hole 41, for example, using an evaporation process.
In this embodiment, the conductive material is, for example, a gold-zinc alloy. The conductive material filled in the second via hole 41 is located on the insulating dielectric layer 234 and serves as a first portion 241 of the ohmic contact structure 240, and the thickness of the first portion 241 is 300 to
The conductive material filled in the contact holes 235 is located in the insulating dielectric layer 234 and the window layer 233 and serves as the second portions 242 of the ohmic contact structures 240, and for each ohmic contact structure 240, the first portions 241 are covered on the contact surfaces of the second portions 242 and the insulating dielectric layer 234. Of course, the conductive material may also be gold beryllium alloy, ITO, IZO or other conductive materials commonly used in the art. After the ohmic contact structure 240 is formed, the second mask is removed, and then the second semiconductor layer 230 and the ohmic contact structure 240 are annealed. And forming good ohmic contact between the ohmic contact structure 240 and the window layer 233 through an annealing step, wherein the annealing temperature is 450-480 ℃, and the annealing time is 15-20 min. Of course, other settings for the annealing time and the annealing temperature may be made by those skilled in the art as desired.
Further, a reflective layer 250 is formed to cover the insulating dielectric layer 234 and the ohmic contact structure 240, as shown in fig. 8.
In this step, a reverse process is formed on the insulating dielectric layer 234 and the ohmic contact structure 240, for example, using an evaporation processAnd an emitting layer 250, wherein the reflecting layer 250 is an Ag mirror reflecting layer or an Au mirror reflecting layer. In the case that the reflective layer 250 is an Ag mirror reflective layer, it is necessary to form stacked Ag, Ti, Pt, and Au layers on the surfaces of the insulating dielectric layer 234 and the ohmic contact structure 240 by using an evaporation process. In the case that the reflective layer 250 is an Au mirror reflective layer, the Au mirror is a single-layer thick Au layer, and an Au layer needs to be formed on the surface of the doping layer and the ohmic contact structure 240 by using an evaporation process. Wherein the thickness range of the reflective layer 250
Further, a first bonding layer 261 is formed on the reflective layer 250, as shown In fig. 9, wherein In the case where the reflective layer 250 is an Ag mirror reflective layer, the material of the first bonding layer 261 is In, and there is good adhesion between In the first bonding layer 261 and the Au layer In the reflective layer 250. In the case where the reflective layer 250 is an Au mirror reflective layer, the first bonding layer 261 may be omitted.
Further, a second bonding layer 302 is formed on the permanent substrate 301, as shown in fig. 10, wherein the material of the second bonding layer 302 is a metal material, and a stacked Ti layer, a Pt layer, and an Au layer are formed on the surface of the permanent substrate 301 by using, for example, an evaporation process.
Further, in the case where the reflective layer 250 is an Ag mirror reflective layer, the first bonding layer 261 and the second bonding layer 302 are bonded, as shown in fig. 11. The growth substrate 10 is removed after the bonding step, wherein In the first bonding layer 261 also has good adhesion with the Au layer In the second bonding layer 302. In the case where the reflective layer 250 is an Au mirror reflective layer, the reflective layer 250 and the second bonding layer 302 are directly bonded.
Further, a second electrode 420 is formed on the permanent substrate 301, and a first electrode 410 is formed on the first semiconductor layer 210, as shown in fig. 12, wherein the second electrode 420 is located on the surface of the permanent substrate 301 away from the bonding layer, and the first electrode 410 is located on the surface of the first semiconductor layer 210 away from the active layer 220. In the present embodiment, the first electrode 410 is an N electrode, and the second electrode 420 is a P electrode.
As shown in fig. 12, the light emitting diode formed according to the above process steps includes: the first semiconductor layer 210, the active layer 220, the second semiconductor layer 230, the insulating dielectric layer 234, the plurality of ohmic contact structures 240, the reflective layer 250, the bonding layer, the permanent substrate 301, the first electrode 410, and the second electrode 420, wherein materials and dimensions of the respective structures may refer to descriptions in the process steps, and are not described herein again. Along the direction from the first electrode 410 to the second electrode 420, the first semiconductor layer 210, the active layer 220, the second semiconductor layer 230, the insulating medium layer 234, the reflective layer 250, the bonding layer, and the permanent substrate 301 are sequentially stacked, wherein the active layer 220 is a multi-layer quantum well structure, a part of light generated by the active layer 220 exits through the first semiconductor layer 210, and another part of light exits through the second semiconductor layer 230 to the reflective layer 250 after being reflected and exits together with light directly passing through the first semiconductor layer 210.
In the present embodiment, each ohmic contact structure 240 covers a portion of the surface of the insulating medium layer 234, each ohmic contact structure 240 extends into the second semiconductor layer 230 through the surface of the insulating medium layer 234, and each ohmic contact structure 240 forms an ohmic contact with the second semiconductor layer 230.
In the present embodiment, the insulating dielectric layer 234 serves to limit the current from the second electrode 420 to the ohmic contact structures 240, and each ohmic contact structure 240 extends from the surface of the insulating dielectric layer 234 into the second semiconductor layer 230. The second semiconductor layer 230 includes a barrier layer 231, a space layer 232, and a window layer 233 stacked in a direction from the first electrode 410 to the second electrode 420, the insulating dielectric layer 234 and the window layer 233 of the second semiconductor layer constitute a single-layer bragg mirror, the refractive index of the insulating dielectric layer 234 is smaller than that of the window layer 233, and each of the ohmic contact structures 240 extends into the window layer 233.
The reflective layer 250 covers the insulating dielectric layer 234 and the ohmic contact structure 240. The bonding layer is used to fixedly connect the permanent substrate 301 and the reflective layer 250, wherein the bonding layer comprises a first bonding layer 261 adjacent to the reflective layer 250 and a second bonding layer 302 adjacent to the permanent substrate 301.
In some embodiments, the plurality of ohmic contact structures 240 are separated from each other. The plurality of ohmic contact structures 240 are arranged according to a predetermined rule, for example, at equal intervals. Of course, the arrangement of the spacing can be modified as desired by those skilled in the art.
Each ohmic contact structure 240 comprises a first part 241 positioned on the insulating medium layer 234 and a second part 242 positioned in the insulating medium layer 234 and the second semiconductor layer 230, and for each ohmic contact structure 240, the first part 241 covers the contact surface of the second part 242 and the insulating medium layer 234, so that the first part 231 shields the ohmic contact surface, and in the subsequent process, other substances cannot be filled in the ohmic contact surface, and the ohmic contact performance is ensured.
In some embodiments, the cross-sectional shape of the ohmic contact structure 240 in a direction parallel to the surface of the insulating dielectric layer 234 is at least one of circular, elliptical, and polygonal, wherein a pattern with the longest cross-sectional shape perimeter is preferred in the case of equal cross-sectional shape area; in one case, if each of the ohmic contact structures 240 having a larger cross-sectional area is divided into two, the total circumference of the cross-section of the divided ohmic contact structures 240 is longer, and thus the ohmic contact area is larger. The cross-sectional shape of the second portion 242 of each ohmic contact structure 240 along the thickness direction of the second semiconductor layer 230 is a shape that is wide at the top and narrow at the bottom or the same width at the top and bottom. Compared to the led structure in fig. 1, the present invention converts two-dimensional ohmic contact into three-dimensional ohmic contact, and the increased ohmic contact area is the area of the sidewall of the ohmic contact structure 240 contacting the window layer 233. In addition, the cross-sectional shape, cross-sectional size, depth, etc. of the ohmic contact structure 240 may be designed according to different design requirements.
According to the light emitting diode and the manufacturing method thereof provided by the embodiment of the invention, the ohmic contact structure and the ohmic contact surface of the second semiconductor layer longitudinally extend to the inside of the second semiconductor layer, so that the area of the ohmic contact surface is increased, the on-resistance of the light emitting diode is reduced, and the purposes of reducing voltage and reducing energy consumption are achieved.
Each ohmic contact structure comprises a first part positioned on the insulating medium layer and a second part positioned in the insulating medium layer and the second semiconductor layer, and for each ohmic contact structure, the first part covers the contact surface of the second part and the insulating medium layer, so that the ohmic contact surface is shielded by the first part, and in the subsequent process, other substances cannot be filled in the ohmic contact surface, and the ohmic contact performance is ensured.
An insulating medium layer is formed through an oxidation step, the insulating medium layer not only can be used as a current limiting layer to limit current in an ohmic contact structure, but also can form a single-layer Bragg reflector with a second semiconductor layer below the insulating medium layer, and particularly, a window layer in the second semiconductor layer not only is used as an ohmic contact layer, but also is used for forming the single-layer Bragg reflector, so that the effect of one-layer multi-purpose is achieved, the process steps are simplified, and the cost is reduced.
The reflecting layer is formed on the single-layer Bragg reflector and combined with the Bragg reflector, so that the reflecting efficiency is further improved, and the light-emitting intensity of the light-emitting surface is improved.
In addition, the ohmic contact surface longitudinally extends into the second semiconductor layer, so that the two-dimensional ohmic contact is converted into the three-dimensional ohmic contact, and the ohmic contact area of the three-dimensional ohmic contact is far higher than that of the two-dimensional ohmic contact, so that the plane area of the light reflecting area occupied by the three-dimensional ohmic contact structure can be properly reduced on the premise of increasing the total area of the ohmic contact, and the light intensity of the light emitting diode can be increased while the voltage is reduced.
The embodiments of the present invention have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.
Claims (51)
1. A light emitting diode comprising:
a first semiconductor layer;
an active layer on the first semiconductor layer;
a second semiconductor layer on the active layer;
the insulating medium layer is positioned on the second semiconductor layer; and
the ohmic contact structures cover part of the surface of the insulating medium layer, each ohmic contact structure extends into the second semiconductor layer through the surface of the insulating medium layer, the bottom and part of the side face of each ohmic contact structure are in contact with the second semiconductor layer, and each ohmic contact structure and the second semiconductor layer form ohmic contact.
2. The light emitting diode of claim 1, wherein the ohmic contact structures are arranged according to a predetermined rule.
3. The light emitting diode of claim 2, wherein the predetermined regular arrangement comprises an arrangement at equal intervals.
4. A light emitting diode according to claim 1 wherein each of said ohmic contact structures comprises a first portion on said insulating dielectric layer and a second portion in said insulating dielectric layer and a second semiconductor layer,
for each ohmic contact structure, the first part covers the contact surface of the second part and the insulating medium layer.
5. The light emitting diode of claim 4, wherein the first portion has a thickness of
6. A light emitting diode according to claim 1 wherein said insulating dielectric layer acts as a current confinement layer to confine current to each of said ohmic contact structures.
7. The light-emitting diode according to claim 4, wherein a cross-sectional shape of the second portion of each of the ohmic contact structures is a shape which is wide at the top and narrow at the bottom in a thickness direction of the second semiconductor layer.
8. The light-emitting diode according to claim 4, wherein a cross-sectional shape of the second portion of each of the ohmic contact structures in a thickness direction of the second semiconductor layer is a shape having the same width in the up-down direction.
9. A light emitting diode according to claim 4 wherein the second portion of the ohmic contact structure is 3 to 5um deep.
10. The light-emitting diode according to claim 1, wherein a cross-sectional shape of the ohmic contact structure in a direction parallel to the surface of the insulating dielectric layer is at least one of circular, elliptical, and polygonal.
11. The light-emitting diode according to claim 1, wherein the ohmic contact structure has a square cross-sectional shape in a direction parallel to the surface of the insulating dielectric layer, and a side length of the square is 4 to 7 um.
12. The light-emitting diode according to claim 4, wherein a cross-sectional area of the first portion of the ohmic contact structure in a direction parallel to the surface of the insulating medium layer accounts for 3% to 9% of an area of a light-emitting area of the light-emitting diode.
13. The light emitting diode of claim 1, wherein the insulating dielectric layer and the second semiconductor layer constitute a single-layer Bragg reflector mirror,
the refractive index of the insulating medium layer is smaller than that of the second semiconductor layer.
14. The light emitting diode of claim 1, wherein the insulating dielectric layer has a thickness of 100 to 200 nm.
15. A light emitting diode according to claim 1 wherein said insulating dielectric layer is obtained by oxidation of a contact layer.
16. The light emitting diode of claim 15, wherein the material of the contact layer and the second semiconductor layer comprises at least one Al-containing compound of AlGaAs, AlGaInP, and AlInP,
wherein an Al component in the aluminum-containing compound of the contact layer is greater than an Al component in the aluminum-containing compound of the second semiconductor layer.
17. The light emitting diode of claim 16, wherein the aluminum containing compound is Al x Ga 1-x As，
Al in the second semiconductor layer x Ga 1-x In As, x is between 0.1 and 0.3,
al in the contact layer x Ga 1-x In As, x is between 1 and 0.8.
18. The light emitting diode of claim 16, wherein the aluminum containing compound is Al x Ga 1-x InP，
Al in the second semiconductor layer x Ga 1-x In InP, x is between 0.1 and 0.2,
al in the contact layer x Ga 1-x In InP, x is 1-0.7.
19. The light emitting diode of claim 1, wherein the second semiconductor layer comprises:
a blocking layer on the active layer;
a space layer on the barrier layer; and
a window layer located on the spatial layer,
wherein each of the ohmic contact structures extends into the window layer.
20. A light emitting diode according to claim 19 wherein said window layer is 6 to 8um thick.
21. A light emitting diode according to any one of claims 1-20 further comprising a reflective layer overlying said dielectric layer and said plurality of ohmic contact structures.
22. A light emitting diode according to claim 21 wherein said reflective layer is an Ag mirror reflective layer or an Au mirror reflective layer.
23. A light emitting diode according to claim 21 further comprising:
a permanent substrate on the reflective layer; and
and the bonding layer is positioned between the permanent substrate and the reflecting layer so as to fixedly connect the permanent substrate and the reflecting layer.
24. A light emitting diode according to claim 23 further comprising:
the first electrode is positioned on the surface of the first semiconductor layer, which is far away from the active layer; and
and the second electrode is positioned on the surface of the permanent substrate far away from the bonding layer.
25. A method of manufacturing a light emitting diode, comprising:
forming a first semiconductor layer on a growth substrate;
forming an active layer on the first semiconductor layer;
forming a second semiconductor layer on the active layer;
forming an insulating medium layer on the second semiconductor layer; and
forming a plurality of ohmic contact structures, covering part of the surface of the insulating medium layer, wherein each ohmic contact structure extends into the second semiconductor layer through the surface of the insulating medium layer, the bottom and part of the side surface of each ohmic contact structure are in contact with the second semiconductor layer, and each ohmic contact structure and the second semiconductor layer form ohmic contact.
26. The method of manufacturing of claim 25, wherein forming the insulating dielectric layer comprises:
forming a contact layer on the second semiconductor layer; and
oxidizing the contact layer to form an insulating dielectric layer,
wherein the insulating medium layer acts as a current confinement layer to confine current to each of the ohmic contact structures.
27. The manufacturing method according to claim 25, wherein the insulating dielectric layer and the second semiconductor layer constitute a single-layer Bragg mirror,
the refractive index of the insulating medium layer is smaller than that of the second semiconductor layer.
28. The method of claim 26, wherein the material of the contact layer and the second semiconductor layer comprises at least one Al-containing compound of AlGaAs, AlGaInP, and AlInP,
wherein an Al component in the aluminum-containing compound of the contact layer is greater than an Al component in the aluminum-containing compound of the second semiconductor layer.
29. The production method according to claim 28, wherein the aluminum-containing compound is Al x Ga 1-x As，
Al in the second semiconductor layer x Ga 1-x In As, x is between 0.1 and 0.3,
al in the contact layer x Ga 1-x In As, x is between 1 and 0.8.
30. The production method according to claim 28, wherein the aluminum-containing compound is Al x Ga 1-x InP，
Al in the second semiconductor layer x Ga 1-x In InP, x is between 0.1 and 0.2,
al in the contact layer x Ga 1-x In InP, x is between 1 and 0.7.
31. The method of manufacturing of claim 26, wherein the step of oxidizing the contact layer comprises a moisture oxidation.
32. The manufacturing method according to claim 25, wherein the step of forming the second semiconductor layer comprises:
forming a barrier layer on the active layer;
forming a space layer on the barrier layer; and
a window layer is formed on the space layer,
wherein each of the ohmic contact structures extends into the window layer.
33. The method of manufacturing of claim 32, wherein the step of forming a plurality of ohmic contact structures comprises:
forming a first mask on the insulating medium layer, wherein the first mask is provided with a first through hole;
etching the insulating medium layer and the window layer through the first through hole to form a contact hole; and
and filling a conductive material in the contact hole to form the ohmic contact structure.
34. The method of manufacturing of claim 33, wherein prior to filling the conductive material, the step of forming a plurality of ohmic contact structures further comprises:
removing the first mask; and
forming a second mask on the insulating medium layer, wherein the second mask is provided with a second through hole, the position of the second through hole corresponds to the first through hole, the aperture of the second through hole is larger than that of the first through hole,
wherein the conductive material is further filled in the second via hole, the conductive material filled in the second via hole is located on the insulating medium layer and serves as a first portion of the ohmic contact structure, the conductive material filled in the contact hole is located in the insulating medium layer and the window layer and serves as a second portion of the ohmic contact structure,
for each ohmic contact structure, the first portion overlies a contact surface of the second portion with the window layer.
35. The manufacturing method according to claim 34, wherein a difference between the hole diameters of the second through hole and the first through hole is 2 to 3 um.
36. The method of claim 25, wherein the ohmic contact structures are arranged according to a predetermined pattern.
37. The manufacturing method according to claim 36, wherein the predetermined regular arrangement includes an arrangement at equal intervals.
38. The method of manufacturing of claim 34, wherein the first portion of the ohmic contact structure has a thickness of
39. The method of manufacturing according to claim 34, wherein the second portion of the ohmic contact structure has a depth of 3 to 5 um.
40. The manufacturing method according to claim 25, wherein a cross-sectional shape of the ohmic contact structure in a direction parallel to the surface of the insulating dielectric layer is at least one of a circle, an ellipse, and a polygon.
41. The manufacturing method according to claim 25, wherein a cross-sectional shape of the ohmic contact structure in a direction parallel to the surface of the insulating dielectric layer is a square having a side length of 4 to 7 um.
42. The manufacturing method according to claim 34, wherein a cross-sectional area of the first portion of the ohmic contact structure in a direction parallel to the surface of the insulating dielectric layer accounts for 3% to 9% of an area of a light emitting region of the light emitting diode.
43. The method of manufacturing of claim 34, further comprising: and annealing the second semiconductor layer and the ohmic contact structure.
44. The method of manufacturing of claim 25, wherein the insulating dielectric layer has a thickness of 100 to 200 nm.
45. The method of manufacturing of claim 32, wherein the window layer is 6 to 8um thick.
46. The manufacturing method according to claim 34, wherein a cross-sectional shape of the second portion of each of the ohmic contact structures is a shape which is wide at the top and narrow at the bottom in a thickness direction of the second semiconductor layer.
47. The manufacturing method according to claim 34, wherein a cross-sectional shape of the second portion of each of the ohmic contact structures in a thickness direction of the second semiconductor layer is a shape having the same width in the upper and lower directions.
48. The method of manufacturing according to any one of claims 25-47, further comprising forming a reflective layer overlying the insulating dielectric layer and the plurality of ohmic contact structures.
49. The manufacturing method according to claim 48, wherein the reflective layer is an Ag mirror reflective layer or an Au mirror reflective layer.
50. The method of manufacturing of claim 48, further comprising:
forming a first bonding layer on the reflective layer;
forming a second bonding layer on the permanent substrate;
bonding the first bonding layer and the second bonding layer; and
and removing the growth substrate.
51. The method of manufacturing of claim 50, further comprising:
forming a first electrode on the surface of the first semiconductor layer far away from the active layer; and
and forming a second electrode, wherein the second electrode is positioned on the surface of the permanent substrate far away from the bonding layer.
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