CN112768484A - Light emitting diode and manufacturing method thereof - Google Patents

Light emitting diode and manufacturing method thereof Download PDF

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Publication number
CN112768484A
CN112768484A CN201911067851.7A CN201911067851A CN112768484A CN 112768484 A CN112768484 A CN 112768484A CN 201911067851 A CN201911067851 A CN 201911067851A CN 112768484 A CN112768484 A CN 112768484A
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light
layer
electrode
transparent substrate
type semiconductor
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CN112768484B (en
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何安和
林素慧
王�锋
夏章艮
詹宇
洪灵愿
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Xiamen Sanan Optoelectronics Technology Co Ltd
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Xiamen Sanan Optoelectronics Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
    • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
    • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • 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
    • H01L33/02—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 semiconductor bodies
    • H01L33/20—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 semiconductor bodies with a particular shape, e.g. curved or truncated substrate
    • 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
    • H01L33/38—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 with a particular shape
    • H01L33/382—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 with a particular shape the electrode extending partially in or entirely through the semiconductor body
    • 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
    • H01L33/38—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 with a particular shape
    • H01L33/385—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 with a particular shape the electrode extending at least partially onto a side surface of the semiconductor body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0016—Processes relating to electrodes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Led Devices (AREA)

Abstract

The invention discloses a light emitting diode and a manufacturing method thereof. In some embodiments, the light emitting diode includes a transparent substrate having a first surface and a second surface opposite to each other, and a sidewall connecting the first surface and the second surface; the light-emitting table top is formed on the first surface of the transparent substrate and comprises a light-emitting epitaxial lamination layer, and the light-emitting epitaxial lamination layer is formed by stacking a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer from the first surface of the transparent substrate; the supporting layer is formed at the periphery of the light-emitting epitaxial lamination layer and forms a plane with the light-emitting table top, and the cross sectional area of the plane is not lower than that of the first surface of the transparent substrate; a first electrode disposed on the plane and electrically connected to the first conductive type semiconductor layer; and a second electrode disposed on the plane and electrically connected to the second conductive type semiconductor layer.

Description

Light emitting diode and manufacturing method thereof
Technical Field
The invention relates to the technical field of semiconductors, in particular to a flip-chip light emitting diode and a manufacturing method thereof.
Background
A Light Emitting Diode (LED) is a semiconductor device that emits light by using energy released during carrier recombination, and particularly, a flip-chip LED chip thereof has been widely used due to advantages of low energy consumption, long service life, energy saving, environmental protection, and the like. Small-sized LEDs have been of particular interest in recent two years as a new technology with a wide market prospect, where Micro-LEDs without transparent substrate support are currently difficult to commercialize on a large scale in a short time due to uncertain technical routes and high costs, while Mini-LEDs with transparent substrate support have begun to be applied in LCD backlights and small-pitch RGB display products.
With the continuous improvement of the pixel requirements of the display screen, the pixel pitch is required to be smaller, the size of the flip LED chip and the packaging device thereof is smaller, and the difficulty and challenge in the manufacturing process are increased. Fig. 31 shows a conventional small-sized flip LED chip, which includes a transparent substrate 110, a light-emitting epitaxial stack on the lower surface of the transparent substrate 110, an insulating layer 130 covering the surface and sidewalls of the light-emitting epitaxial stack, and first and second electrodes 141 and 142. The light emitting epitaxial stack generally includes a first conductive type semiconductor layer 121, an active layer 122, and a second conductive type semiconductor layer 123, and further, a current spreading layer 150 may be formed on a surface of the second conductive type semiconductor layer 123. In the led structure, the limited electrode area is a difficult problem in the die bonding process. The flip-chip LED chip has a small electrode area due to the inward shrinkage of metal electrodes (Bonding pads), especially for Mini-LEDs, the size of the Mini-LEDs with the current yield has reached 3mil × 5mil, and the size will be further reduced in the future, and the gap between the electrodes is usually required to be 15-50 μm, so the size of the electrodes is limited, which is not enough to cover the area of solder paste brushing during the die Bonding, and the solder paste 160 is likely to overflow to the side surface of the chip or between P, N electrodes during the die Bonding process, as shown in fig. 32, resulting in short circuit. Further, the limited solder paste contact area generally results in a low thrust force, which causes problems such as poor heat dissipation and poor high temperature and high humidity characteristics.
Disclosure of Invention
The present invention is directed to a light emitting diode and a method for fabricating the same, which can enlarge the surface of the die attach electrode of a flip chip light emitting diode chip and improve the chip bonding characteristics.
According to a first aspect of the present invention, a light emitting diode includes: the transparent substrate is provided with a first surface, a second surface and a side wall, wherein the first surface and the second surface are opposite, and the side wall is connected with the first surface and the second surface; the light-emitting table top is formed on the first surface of the transparent substrate and comprises a light-emitting epitaxial lamination layer, and the light-emitting epitaxial lamination layer is formed by stacking a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer from the first surface of the transparent substrate; the supporting layer is formed at the periphery of the light-emitting epitaxial lamination layer and forms a plane with the light-emitting table top, and the cross sectional area of the plane is not lower than that of the first surface of the transparent substrate; a first electrode disposed on the plane and electrically connected to the first conductive type semiconductor layer; and a second electrode disposed on the plane and electrically connected to the second conductive type semiconductor layer.
Further, the light emitting mesa may include an insulating layer covering at least an upper surface and a sidewall of the light emitting epitaxial stack and having a first opening through which the first electrode is electrically connected to the first conductive type semiconductor layer and a second opening through which the second electrode is electrically connected to the second conductive type semiconductor layer. The supporting layer is provided with a third surface which is flush with the surface of the insulating layer to form the plane.
Preferably, the insulating layer is an insulating layer, and the support layer is a colored material layer. In some embodiments, the light emitting diode may be applied to RGB application screens, and the support layer is preferably black glue, which may increase the contrast of the display screen.
In some embodiments, the support layer partially covers sidewalls of the transparent substrate.
Preferably, the support layer has a fourth surface flush with the second surface of the transparent substrate.
Preferably, the thickness of the supporting layer covering the side wall of the transparent substrate is 2-20 μm.
Preferably, the first electrode and the second electrode are in a multilayer structure, and the bottom layer is one or a combination of multiple stacked layers of metal materials of Cr, Al, Ti, Ni, Pt and Au. In some embodiments, the surface layers of the first and second electrodes are Sn-containing metal materials, and in other embodiments, the surface layers of the first and second electrodes are Au metal materials.
In some embodiments, the edge of the first surface of the transparent substrate has a side length of 200-300 μm, or 100-200 μm, or 40-100 μm.
In some embodiments, the light emitted from the active layer exits from the second surface of the transparent substrate with an exit angle of 135 ° or less.
According to a second aspect of the present invention, a method for manufacturing a light emitting diode includes the steps of: forming a light emitting mesa on a first surface of a transparent substrate, the light emitting mesa including a light emitting epitaxial stack of a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer stacked from the first surface of the transparent substrate; (II) manufacturing a supporting layer which is formed at the periphery of the light-emitting epitaxial lamination layer and forms a plane with the light-emitting table top, wherein the cross sectional area of the plane is not less than that of the first surface of the transparent substrate; (iii) fabricating a first electrode and a second electrode on the plane, wherein the first electrode is electrically connected to the first conductive type semiconductor layer; the second electrode is electrically connected to the second conductive type semiconductor layer.
Further, the step (one) further comprises: (1) providing an epitaxial structure comprising a transparent substrate and a light-emitting epitaxial stack, the substrate having a first surface and a second surface, and sidewalls connecting the first surface and the second surface, the light-emitting epitaxial stack being formed on the first surface of the transparent substrate and comprising a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer stacked from the first surface of the transparent substrate; (2) defining a cutting channel on the surface of the light-emitting epitaxial lamination, and dividing the epitaxial structure into a series of light-emitting units along the cutting channel; (3) expanding the spacing between the series of light-emitting units; and (b) a filling material layer between the light-emitting units in the step (two), wherein the filling material layer covers the side walls of the light-emitting units to form the support layer.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way.
Fig. 1(a) and (b) are schematic structural diagrams of a light emitting diode according to a first embodiment, fig. 1(a) is a side sectional view, and fig. 1(b) is a schematic plan view.
Fig. 2 is a schematic structural diagram of a light-emitting device according to an embodiment.
Fig. 3 to 4 are schematic structural views of the light emitting diode according to the second embodiment, fig. 3 is a side sectional view, and fig. 4 is a schematic plan view.
Fig. 5 to 10 are schematic structural diagrams illustrating a manufacturing process flow of a light emitting diode according to a second embodiment, wherein fig. 5 is a side sectional view of an LED epitaxial structure, and fig. 6 is a schematic diagram illustrating a LED chip size defined in the epitaxial structure shown in fig. 5 after communication is formed; FIG. 7 is a schematic illustration of the structure of FIG. 6 after an insulating layer has been formed thereon; FIG. 8 is a schematic illustration after forming electrodes on the structure shown in FIG. 7; FIG. 9 is a schematic view of the structure shown in FIG. 8 after thinning from the second surface of the transparent substrate; fig. 10 is a schematic diagram of the structure shown in fig. 9 cut to form individual LED chips.
Fig. 11 shows a photo of an object of the LED chip shown in fig. 23 formed by stealth-cutting and cleaving.
Fig. 12 is a photograph showing a real object in which the LED chips 100 shown in fig. 11 are arranged on a substrate.
Fig. 13 to 14 are schematic structural diagrams of a manufacturing process flow of the light emitting diode according to the third embodiment, in which fig. 13 is a schematic diagram of the structure shown in fig. 8 after being bonded to a temporary support, and fig. 14 is a schematic diagram of the structure shown in fig. 13 after being thinned to communicate with each other.
Fig. 15 to 16 are schematic structural views of the light emitting diode according to the third embodiment, fig. 15 is a side sectional view, and fig. 16 is a schematic plan view.
Fig. 17 to 20 are schematic structural diagrams illustrating a manufacturing process flow of a light emitting diode according to a fourth embodiment, wherein fig. 17 is a schematic diagram illustrating a LED chip size defined in the epitaxial structure shown in fig. 5 and an insulating layer formed thereon; FIG. 18 is a schematic view of the structure of FIG. 17 after cutting and spreading; FIG. 19 is a schematic illustration after forming a photoresist layer over the structure shown in FIG. 18; fig. 20 is a schematic view of electrodes fabricated on the structure shown in fig. 19.
Fig. 21 to 22 are schematic structural views of the light emitting diode according to the fourth embodiment, fig. 21 is a side sectional view, and fig. 22 is a schematic plan view.
Fig. 23 to 25 are schematic structural views of the light emitting diode according to the fifth embodiment, fig. 23 is a side sectional view, and fig. 24 and 25 are schematic plan views.
Fig. 26 to 30 are schematic structural diagrams illustrating a process flow of fabricating a light emitting diode according to a fifth embodiment, wherein fig. 26 is a schematic diagram illustrating a process flow of defining a size of an LED chip and forming an insulating layer in the epitaxial structure shown in fig. 5; FIG. 27 is a schematic view of the structure shown in FIG. 16 after thinning from the second surface of the transparent substrate; FIG. 28 is a schematic view of the structure of FIG. 27 after cutting and spreading; FIG. 29 is a schematic view of forming a profile support layer on the structure shown in FIG. 28; fig. 30 is a schematic view of electrodes fabricated on the structure shown in fig. 29.
Fig. 31 is a schematic cross-sectional view of a light emitting diode according to the related art.
Fig. 32 is a schematic plan view of a light emitting diode mentioned in the background art.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention.
Example one
The present embodiment discloses a flip-chip LED chip, which includes the following stacked layers as shown in fig. 1 (a): a transparent substrate 210, a light emitting epitaxial stack, an insulating layer 230, a first electrode 241 and a second electrode 242. The LED chip may be a small-sized LED chip having a small horizontal area, for example, may have a size of about 62500 μm2The horizontal cross-sectional area of which is about 900 μm2Above and about 62500 μm2The horizontal cross-sectional area below. For example, the LED chip may have a size of 230 μm × 120 μm or 120 μm × 80 μm or 100 μm × 60 μm or 50 μm × 40 μm. However, the horizontal and vertical lengths of the LE chip of the embodiment are not limited to the above.
The details of each structural stack are described below.
As shown in fig. 1(a), the transparent substrate 210 may be a growth substrate for light emitting epitaxial stack growth, such as a sapphire substrate, or may be a transparent substrate 210 bonded to a light emitting epitaxial stack through a transparent adhesive layer. The transparent substrate 210 includes a first surface 210A, a second surface 210B and a sidewall 210C, wherein the first surface and the second surface are opposite, and the transparent substrate 210 preferably includes a plurality of protrusions formed at least at a partial region of the first surface. For example, the transparent substrate 210 may be a patterned sapphire substrate.
The light emitting diode may be a small light emitting diode having a small horizontal area, and the size of the light emitting diode may be reflected by the size of the first surface of the transparent substrate, for example, the side length of the first surface of the transparent substrate 210 is preferably less than or equal to 300 μm, preferably, between 10 μm and 300 μm, or 100 μm and 200 μm, or less than 100 μm, preferably, between 40 μm and 100 μm. The thickness of the transparent substrate 210 is between 30 μm and 150 μm, and the thickness is between 80 μm and 150 μm in the case of being thicker, and between 30 μm and 80 μm in the case of being thinner. The thickness of the light-emitting epitaxial lamination layer is between 1 and 10 mu m. The light emitting diode of the present embodiment has the above-described size and thickness, and thus the light emitting diode can be easily applied to various electronic devices requiring a small and/or thin type light emitting device.
The first surface portion of the transparent substrate 210 is covered by the light emitting epitaxial stack, so the first surface of the transparent substrate 210 is divided into a first region 210a1 covered internally by the light emitting epitaxial stack and a second region 210a2 surrounding the light emitting epitaxial stack. The light emitting diode reserves a cutting channel with a certain width for a cutting process such as laser stealth cutting and splitting in the manufacturing process, the cutting channel is processed by the cutting process to form a second area 210A2 of the first surface of the transparent substrate 210 around the light emitting epitaxial lamination, and the width of the cutting channel is preferably 10-50 micrometers.
The second surface 210B of the transparent substrate 210 is a light emitting surface of the led and is a main light emitting area.
The second region 210a2 of the first surface of the transparent substrate 210 is not covered by the light emitting epitaxial stack, that is, in the manufacturing process of the semiconductor light emitting device, the light emitting epitaxial stack is singulated on the substrate surface before the substrate is cut, and the second region 210a2 of the first surface of the transparent substrate 210 is exposed, so that the stress generated on the substrate by the light emitting epitaxial stack can be reduced, the bending reduction of the light emitting diode in the manufacturing process can be promoted, the light emitting epitaxial stack is prevented from being damaged, and the manufacturing yield is improved.
As shown in fig. 1(b), the first area covered by the light emitting epitaxial stack is smaller than the horizontal area of the first surface of the transparent substrate 210, as viewed from the top of the second conductive type semiconductor layer. Preferably, the horizontal cross-sectional area of the first region 210a1 of the first surface of the transparent substrate 210 occupies 40% to 90% of the horizontal cross-sectional area of the first surface of the transparent substrate. As dimensions become smaller, the area fraction of the light emitting epitaxial stack also becomes correspondingly smaller. For example when sending hairThe horizontal area of the photodiode, i.e., the area of the first surface of the substrate 210, was 28000 μm2The coverage area ratio of the light-emitting epitaxial stack is about 86%, and the area ratio of the second region 210a2 of the first surface of the substrate around the light-emitting epitaxial stack is 14%. The light emitting epitaxial stack includes the first conductive type semiconductor layer 221, the active layer 222, and the second conductive type semiconductor layer 223, and a specific light emitting epitaxial stack may include a iii-v type nitride based semiconductor, for example, a nitride based semiconductor such As (Al, Ga, In) N or a phosphide based semiconductor including (Al, Ga, In) P or an arsenide based semiconductor including (Al, Ga, In) As. The first conductive type semiconductor layer 221 may include n-type impurities (e.g., Si, Ge, Sn) and the second conductive type semiconductor layer may include p-type impurities (e.g., Mg, Sr, Ba). Also, the above impurity types may be reversed. The active layer may include a multiple quantum well structure (MQW) and the elemental composition ratio of the semiconductor may be adjusted to emit a desired wavelength. In the present embodiment, the second conductive type semiconductor layer may be a p-type semiconductor layer.
The surface of the light-emitting epitaxial lamination layer is provided with at least one first electrode step and/or first electrode through hole which exposes part of the first conductivity type semiconductor layer. In the present embodiment, preferably using the electrode via structure, the light emitting epitaxial stack may include at least one hole 270 penetrating at least partially the active layer 222 and the second conductive type semiconductor layer 223 to expose the first conductive type semiconductor layer 221. The hole 270 partially exposes the first conductive type semiconductor layer 221, and the side surface of the hole 270 may be surrounded by the active layer 222 and the second conductive type semiconductor layer 223.
For electrical connection between the second electrode 242 and the second conductive type semiconductor layer 223, a contact electrode 250 may be disposed on the second conductive type semiconductor layer 223. The contact electrode 250 may be in ohmic contact with the second conductive type semiconductor layer 223. The contact electrode 250 may include a transparent conductive layer. The transparent conductive layer may further include at least one of a light-transmitting conductive oxide such as indium tin oxide, zinc indium tin oxide, indium zinc oxide, zinc tin oxide, gallium indium tin oxide, indium gallium oxide, zinc gallium oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, or the like, and a light-transmitting metal layer such as Ni/Au, or the like, for example. The conductive oxide may also include various dopants. Preferably, the thickness of the contact electrode 250 is 50 to 300 nm. The surface contact resistance of the contact electrode 250 with the second conductive type semiconductor layer 223 is preferably lower than the surface contact resistance of the metal electrode with the second conductive type semiconductor layer 223, so that the forward voltage can be reduced and the light emitting efficiency can be improved.
An insulating layer 230 covers the top surface 220B and sidewalls of the light emitting epitaxial stack and the second region 210a2 of the first surface of the transparent substrate 210. Specifically, when the contact electrode 250 is present, the contact electrode 250 and the top surface and sidewalls of the light emitting epitaxial stack not covered by the contact electrode 250 are both covered by the insulating layer 230. And the insulating layer 230 may further at least partially or completely cover the second region 210B exposed on the first surface of the transparent substrate, which may ensure that it covers the sidewall of the light emitting epitaxial stack more stably, and simultaneously prevent moisture from entering the periphery of the light emitting epitaxial stack, thereby reducing the risk of electrical leakage.
Preferably, the insulating layer 230 is an insulating reflective layer covering the top surface and the sidewalls of the light emitting epitaxial stack, and when light radiated by the light emitting layer reaches the surface of the insulating layer 230 through the contact electrode 250, most of the light may be reflected back into the light emitting epitaxial stack by the insulating layer 230 and most of the light is extracted through the second surface side of the transparent substrate, reducing light loss caused by light exiting from the light emitting epitaxial stack surface and the sidewalls. Preferably, the insulating layer 230 is capable of reflecting at least 80% or further at least 90% of the intensity of light radiated by the light-emitting layer reaching the surface thereof. The insulating layer 230 may specifically include a bragg reflector. The bragg reflector may be formed in such a manner that at least two insulating media having different refractive indexes are repeatedly stacked, and may be formed in 4 to 20 pairs, for example, the insulating layer may include TiO2、SiO2、HfO2、ZrO2、Nb2O5、MgF2And the like. In some embodiments, the insulating layer 230 may be deposited with TiO alternately2layer/SiO2And (3) a layer.
Each layer of the bragg reflector may have an optical thickness of 1/4 a peak wavelength of a radiation band of the light emitting layer. The uppermost layer of the bragg reflector may be formed of SiNx. The layer formed of SiNx is excellent in moisture resistance, and can protect the light emitting diode from moisture.
In the case where the insulating layer 230 includes a bragg reflector, the lowermost layer of the insulating layer 230 may have a bottom layer or an interface layer that improves the film quality of the distributed bragg reflector. For example, the insulating layer 230 may comprise SiO with a thickness of about 0.2-1.0 μm2Forming an interface layer and stacking a TiO layer on the interface layer at a specific period2/SiO2。
The insulating layer 230 may also be a single insulating layer only, preferably having a reflectivity generally lower than that of the bragg reflector, at least 40% of the light exiting the insulating layer 230, preferably at least 1 μm or more preferably a thickness of 2 μm or more, such as SiO2The LED has excellent moisture resistance and can protect the LED from moisture.
The insulating layer 230 has at least one first opening 271 and one second opening 272, and the first electrode 241 and the second electrode 108 are formed on the surface of the insulating layer 230. The first electrode 241 is electrically connected to the first electrode contact region of the first conductive type semiconductor layer 221 through the first opening 271, and the second electrode 242 is electrically connected to the contact electrode 250 on the surface of the second conductive type semiconductor layer 223 through the second opening 272. The contact electrode 250 may also have one or more openings, and the second electrode 242 may be in contact with the surface of the second conductive type semiconductor layer partially through the one or more openings of the contact electrode 250. Preferably, the resistance between the second electrode 242 and the second conductive type semiconductor layer 223 is higher than the resistance between the contact electrode 250 and the second conductive type semiconductor layer 223 to minimize current crowding directly at a position where the second electrode contacts the second conductive type semiconductor layer.
Referring to fig. 1(a) and (B), at least one of the first and second electrodes 242 includes a planar electrode 241A (or 242A) on the upper surface of the light-emitting epitaxial stack and a sidewall electrode 241B (or 242B) covering the side surface of the light-emitting epitaxial stack, wherein the sidewall electrode contacts the second region 210a2 on the first surface of the substrate 210. In some embodiments, the first and second electrodes 241 and 242 may have upper surface distributions corresponding to surface distributions of lower surfaces of portions forming the first and second electrodes 241 and 242, respectively. Thus, the first electrode 241 may include a recess (not shown) on the first opening 271, and the second electrode 242 may include a recess (not shown) on the second opening 272, so that the contact area between the first electrode 241 and the second electrode 242 is increased, and a step is generated at the contact portion to prevent the first electrode 241 and the second electrode 242 from being peeled off.
The first electrode 241 and/or the second electrode 242 extend towards the side wall of the LED chip and contact a part of the first surface of the substrate of the LED chip, a side wall electrode is formed in the cutting path area, the surface area of the electrode of the LED chip can be enlarged, for example, the surface area of the electrode of the LED chip can be 3mil multiplied by 5mil, the conventional electrode can be 30 multiplied by 50 mu m, the electrode coverage of the side wall of the cutting path is increased, the width of the cutting path covered by the electrode can be about 6 mu m, and the surface area of a single electrode can be increased by 660 mu m2(50X 6+ 30X 6X 2) to cover the solder paste area enough during packaging, thereby preventing the solder paste from overflowing to the side of the chip or causing electrical short circuit between electrodes during die bonding. In a preferred embodiment, the first electrode and the second electrode cover the sidewalls of the light emitting epitaxial stack except for the electrode isolation region and partially cover the scribe line region of the first surface of the substrate 210. For the small-sized LED chip shown in fig. 1, for example, in a flip chip with a size of 230 μm × 120 μm, or 120 μm × 80 μm, or 100 μm × 60 μm, or 50 μm × 40 μm, the area occupied by the light-emitting epitaxial stack is relatively small, and the second area of the first surface of the substrate 210 around the light-emitting epitaxial stack is relatively large, so that the size of the electrode formed on the upper surface 220B of the light-emitting epitaxial stack is small, and the surface area of the electrode can reach 90% to 120% of the area of the first surface of the substrate 210 by extending the electrode to the exposed upper surface of the substrate 210, which is beneficial for improving the die bonding yield in subsequent packaging.
Preferably, the sidewall electrode 241B (or 242B) and the planar electrode 241A (or 242A) have the same material layer, and may be a single-layer or multi-layer structure, and the sidewall electrode and the planar electrode may be formed in the same process, so that the integrity of the sidewall electrode and the planar electrode may be maintained, and the sidewall electrode and the planar electrode are prevented from being disconnected or even peeled off.
The thickness of the sidewall electrode 241B (or 242B) may be 1 to 10 μm, preferably 3 to 8 μm, for example, 6 μm. The sidewall electrode having such a thickness range is advantageous for bonding with a bonding material (for example, solder such as solder paste) of the package substrate, and good connection is formed.
In the embodiment, at least one of the first electrode 217 and the second electrode 272 covers the top surface and the side wall of the light-emitting epitaxial lamination layer at the same time, and covers the ISO cutting channel except the electrode isolation region, so that the surface area of the electrode is increased, and when eutectic connection is performed with the packaging substrate, due to the shrinkage force of metal materials such as Au and Ni on the solder paste, the eutectic die bonding solder paste has the function of converging and solidifying the solder paste, and short circuit caused by solder paste overflow is reduced; further, the electrode covers the insulating layer 230 on the sidewall of the light emitting epitaxial stack, increasing the pulling capability of the sidewall structure and solder paste stress, and protecting the insulating layer 230 from cracking.
Fig. 2 shows a light emitting device using the led chip shown in fig. 1, which includes a carrier substrate 260, the led chip located on the substrate 260, a first bonding portion 261, and a second bonding portion 262. The carrier substrate 260 may provide a region where the LED chip is mounted, and may be a substrate of a light emitting diode package or a substrate of a light emitting module, for example. The carrier substrate 260 has a first conductive pattern 263 and a second conductive pattern 264 on a surface thereof. The carrier substrate 260 may include a conductive substrate, an insulating substrate, or a Printed Circuit Board (PCB). The LED chip is located on the carrier substrate 260 and electrically connected to the carrier substrate 260. The first and second bonding portions 261 and 262 are located between the LED chip and the carrier substrate 260 to bond the LED chip to the carrier substrate 260 and are electrically connected to each other. The first bonding part 261 may be in contact with the first electrode 241 of the LED chip and in contact with the first conductive pattern 263 of the carrier substrate 260, and the second bonding part 262 may be in contact with the second electrode 242 of the LED chip and in contact with the second conductive pattern 264 of the carrier substrate 260. The first bonding portion 261 and the second bonding portion 262 are not limited as long as they are substances that electrically connect the LED chip and the second bonding portion 263 of the carrier substrate and bond them to each other, and may include, for example, solder. At least one of the first and second bonding portions 261 and 262 is simultaneously in contact with the planar electrode 241A (or 242A) and the sidewall electrode 241B (or 242B) of the LED chip.
In this embodiment, the first bonding portion 261 and the second bonding portion 262 cover at least a portion of the side electrode 241B (or 242B) covering the side surface of the light emitting epitaxial stack in addition to the planar electrodes 241A and 242A, so as to increase the electrode contact area between the bonding portion and the LED chip, have a function of converging die bonding solder paste, and reduce short circuit caused by solder paste overflow. Furthermore, the side surface of the LED chip is used as one of the bonding surfaces between the LED chip and the carrier substrate 260, and the distance D2 between the first bonding portion 261 and the second bonding portion 263 can be increased to be larger than the distance D1 between the first electrode and the second electrode, thereby reducing the risk of short circuit between the first bonding portion and the second bonding portion. Further, the sidewall electrode is arranged between the insulating layer and the joint part of the sidewall of the light-emitting epitaxial stack, so that the sidewall structure and the pulling capacity of solder stress are increased, the insulating layer 230 is protected from being cracked, and the first joint part 261 and the second joint part 262 are prevented from being electrically short-circuited with the side surface of the light-emitting epitaxial stack due to the cracking of the insulating layer.
Example two
Fig. 3 and 4 show another flip-chip LED chip implemented in accordance with the present invention. Unlike the first embodiment, the outer periphery of the first surface 210A of the transparent substrate 210 has a step 211, the step 211 has a third surface 210D between the first surface 210A and the second surface 210B, and a sidewall 210E connecting the first surface and the third surface, and the first electrode 241A and/or the second electrode 242 extends to the step 211 to at least partially cover the sidewall 210E connecting the first surface and the third surface 210D. The distance from the third surface 210D to the first surface 210A is preferably 10-40 μm, such as 20-30 μm, and the distance from the third surface to the second surface is preferably 10-60 μm, such as 30-50 μm. By providing the step 211 at the outer periphery of the transparent substrate 210 and extending the first electrode and/or the second electrode to the step 211, the LED core can be further increasedSurface area of the sheet electrode. About 62500 μm for horizontal cross-sectional area2The following small-sized LED chip, particularly with a horizontal cross-sectional area of 22500 μm2For example, in the case of a 120 μm × 80 μm or 100 μm × 60 μm or 50 μm × 40 μm LED chip, the width W1 of the step 211 is preferably 5 to 20 μm, and when the width of the step is less than 5 μm, there is a possibility that there is not enough contact area for receiving the electrode located on the sidewall of the LED chip, and when the width of the step exceeds 20 μm, it is disadvantageous to reduce the size of the LED chip.
The LED chip coats the electrode on part of the side wall 210E of the transparent substrate, and can reflect light rays emitted to the side wall 210E of the transparent substrate by the active layer, so that the luminous efficiency is improved. Furthermore, the light-emitting angle of the LED chip can be adjusted by adjusting the position of the third surface of the step, for example, when small-angle light emission is required, the distance from the third surface to the second surface can be reduced as much as possible, so that most of the side wall of the transparent substrate is coated by the electrode, and the light emission from the side wall of the LED chip is reduced. In a preferred embodiment, the first electrode and the second electrode simultaneously cover the sidewalls of the steps except for the electrode isolation region and contact the third surface, as shown in fig. 4.
The insulating layer 230 covers at least the top surface 220B and sidewalls of the light emitting epitaxial stack and the exposed area of the first surface of the transparent substrate 210. And the insulating layer 230 can further at least partially or completely cover the sidewall 210E of the step of the transparent substrate, which can ensure that it can more stably cover the sidewall of the light-emitting epitaxial stack, and simultaneously prevent water vapor from entering the periphery of the light-emitting epitaxial stack, thereby reducing the risk of electric leakage.
The following describes the manufacturing process of the LED chip of this embodiment in detail.
As shown in fig. 5, a light emitting epitaxial stack including a first conductive type semiconductor layer 221, an active layer 222, and a second conductive type semiconductor layer 223 sequentially stacked is formed on the first surface 210A of the transparent substrate 210.
As shown in fig. 6, a scribe line and an electrode region are defined on the light emitting epitaxial stack according to the size of the LED chip, the second conductive type semiconductor layer 223 and the active layer 222 of the electrode region are etched through one or more masks to form a hole 270, the hole 270 exposes a portion of the surface 221A of the first conductive type semiconductor layer, the second conductive type semiconductor layer 223, the active layer 222 and the first conductive type semiconductor layer 221 of the scribe line region are etched to form a trench 280, the bottom of the trench 280 penetrates into the transparent substrate 210, a sidewall 210E is formed in the transparent substrate, that is, the bottom surface 210C of the trench 280 is located between the first surface 210A and the second surface 210B of the transparent substrate, and the depth of the trench 280 penetrating into the transparent substrate is determined by the position of the third surface 210D of the mesa 211 of the light emitting diode chip shown in fig. 3. In a specific embodiment, the second conductive type semiconductor layer 223 and the active layer 222 in the electrode region may be removed by dry etching to form the hole 270, and then the channel 280 may be formed by laser etching the light emitting epitaxial stack of the scribe line.
As shown in fig. 7, the plating insulating layer 230 covers the surface and the sidewall of the light emitting epitaxial stack and the exposed region of the first surface of the transparent substrate 210. Further, the insulating layer 230 may also partially cover the sidewall 210E of the trench. In the conventional coating process, such as evaporation or sputtering, the thickness of the insulating layer 230 on the sidewall of the light-emitting epitaxial stack is generally lower than the thickness of the top surface of the light-emitting epitaxial stack and the second region of the first surface of the transparent substrate due to the shadow effect, so that the thickness on the sidewall of the light-emitting epitaxial stack is 40-90% of the thickness of the top surface of the semiconductor sequence. In one embodiment, the contact electrode 250 is formed on the surface of the second conductive type semiconductor layer 223, and the material may be ITO, GTO, GZO, ZnO, or a combination of several materials, and then the insulating layer 230 is formed.
The insulating layer 230 forms a first opening 271 in the first electrode electrical connection region of the first conductive type semiconductor layer 221, and forms a second opening 272 in the surface of the contact electrode 250.
As shown in fig. 8, the first electrode and the second electrode are formed by photolithography and evaporation processes, and the electrodes cover the sidewalls of the light emitting epitaxial stack and the sidewalls 210E of the channel and contact the bottom surface 210D of the channel 280. The minimum horizontal pitch of the first and second electrodes 241 and 242 on the insulating layer 230 is preferably 5 μm, and the material may be a combination of metals such as Cr, Pt, Au, Ti, Ni, Al, and the like. Preferably, the electrode is a multilayer structure, and the surface layer of the electrode is preferably made of Au material. The electrode layer on the upper surface of the light-emitting epitaxial lamination and the electrode layer on the side wall are formed in the same step and contact with the bottom of the communication layer, so that the integrity of the electrode is ensured, and the side wall electrode is prevented from falling off or breaking.
As shown in fig. 9, thinning is performed from the second surface 210B of the transparent substrate 210 using a grinding apparatus according to the thickness requirement of the chip. Preferably, the thickness of the substrate may be 150 μm or less. For small-sized LED chips, the thickness is preferably less than 100 μm, for example, 40 to 80 μm.
As shown in fig. 10, the transparent substrate 210 is singulated to form individual led chips. In one embodiment, the transparent substrate is a sapphire substrate, the laser beam scans the scribe line to form a plurality of modified explosion points in the transparent substrate below the scribe line, and the cleaving blade cleaves the transparent substrate 210 along the scribe line to form the individual led chip as shown in fig. 3.
In the embodiment, the trench is formed deep into the transparent substrate 210 at the scribe line, and the electrode is formed on the sidewall of the trench, so that on one hand, the surface area of the electrode can be increased, and on the other hand, in the subsequent grinding and thinning process, the communication is favorable for releasing the stress, and especially for a thinner LED chip, for example, an LED chip with a thickness of 80 μm or less, the warpage generated in the grinding process of the transparent substrate 210 can be effectively reduced.
EXAMPLE III
In the LED chip supported by the transparent substrate, after the transparent substrate is thinned, the LED chip is usually cut in a manner of stealth cutting combined with cleaving. For a particle having a diameter of about 62500 μm2For example, the LED chip may have a size of 230 μm × 120 μm, or 120 μm × 80 μm, or 100 μm × 60 μm, or 50 μm × 40 μm, when the size of the chip is smaller, the size of the cutting track reserved at the periphery of the light emitting epitaxial stack is limited, and the problem of cutting edge distortion and even edge chipping often occurs during the cleaving process. FIG. 11 shows a pattern 31 formed by stealth-cutting, cleavingA pictorial photograph of the LED chip shown. The off-white portion 110a1 of each LED chip is the surface of the transparent substrate exposed at the periphery of the light-emitting mesa 120 in the LED chip, a cutting street with a certain width is reserved in the area for a cutting process such as laser stealth cutting and splitting, the cutting street is processed by the cutting process to form a cutting street area of the transparent substrate around the light-emitting mesa, each LED chip has four cutting edges 110B1, as can be seen from the figure, the edges of most LED chips are distorted, so that the LED chips have irregular shapes, and fig. 12 shows a physical photograph diagram in which the LED chips 100 shown in fig. 11 are arranged on the substrate. It can be seen from the figure that the LED chip back surface (the back surface of the transparent substrate) is irregular in shape.
Fig. 13 to 14 show a method for manufacturing an LED chip according to still another embodiment of the present invention, which can obtain a small-sized LED chip with regular shape.
First, the method shown in fig. 5 to 8 is used to form a trench 280 on the light emitting epitaxial structure and to fabricate the first electrode 241 and the second electrode 242, and the specific steps can refer to the description of the second embodiment. As shown in fig. 13, the epitaxial structure shown in fig. 8 is attached to a support film or bonded to a temporary substrate 290; as shown in fig. 14, the epitaxial structure shown in fig. 8 is divided into a series of individual LED chips by thinning from the second surface 210B of the transparent substrate using a grinding apparatus and polishing to the depth of the trench 280.
In this embodiment, a trench 280 is formed in the scribe line region by laser etching or dry etching, the bottom of the trench 280 penetrates into the transparent substrate 210, the depth of the trench is determined according to the thickness of the chip, and then the trench is thinned from the second surface of the transparent substrate to the position of the trench 280 by mechanical methods such as grinding, so as to form a series of independent LED chips.
Fig. 15 and 16 show a flip LED chip formed using the above method. The LED chip has regular cutting edges, the first electrode 241 and the second electrode 242 completely cover the side wall of the transparent substrate except for the electrode separation region, on one hand, the surface area of the electrodes can be increased, on the other hand, the light-emitting outer table surface of the LED can be protected and supported, and the LED chip is more suitable for thin small-size LED chips, for example, the thickness of the LED chip is less than 60 micrometers, 10-50 micrometers, particularly the thickness of the LED chip is less than 40 micrometers, and the thickness of the transparent substrate is reduced to less than 40 micrometers, and the physical supporting strength of the transparent substrate can be increased through the electrode coating of the LED chip.
In an embodiment, the transparent substrate at the outer periphery of the light emitting epitaxial mesa is substantially removed, and the area of the transparent substrate 210 is close to that of the light emitting mesa, so that the actual size of the LED chip can be further reduced.
Referring to fig. 16, most of the side walls of the LED chip are covered by the electrodes, and only the electrode isolation regions are left, so that most of the light emitted from the active layer to the side walls is reflected, the light emitting angle of the chip is reduced, the light emitting angle can reach below 135 °, the side walls are substantially not light, and the chip can be applied to COB or RBG displays, and the package end does not need to be coated with black glue on the side surfaces, thereby achieving a high contrast effect.
In some embodiments, the LED wafer may not be thinned to the position of the channel 280, i.e., a certain thickness is formed between the back surface of the transparent substrate and the bottom of the communication, and the transparent substrate is stressed to crack the LED wafer along the communication 280, thereby forming a plurality of LED chips. Preferably, the thickness is 20 μm or less, for example, 3 to 12 μm, and in this range, the cleaving is not necessary, and the residual thickness is small, and the range in which the cut edge is deviated is small, and the distortion is not easily generated.
Example four
Fig. 17 to 20 show a method of manufacturing an LED chip according to still another embodiment of the present invention, which can obtain a flip LED chip having electrodes with a larger size. The following is a brief description with reference to the drawings.
First, defining a scribe line and a mesa on the epitaxial structure shown in fig. 5 according to the size of the LED chip, etching to remove the light emitting epitaxial stack in the scribe line region, forming a scribe line 280, dividing the light emitting epitaxial stack into a series of light emitting mesas, forming a contact electrode 250 and an insulating layer 230 on each light emitting mesa, wherein the insulating layer 230 covers at least the upper surface and the sidewall of the light emitting mesa, forming a first opening 271 in the first electrode electrical connection region of the first conductive type semiconductor layer 221, and forming a second opening 272 on the surface of the contact electrode 250, as shown in fig. 17; cutting the transparent substrate 210 along the cutting path 280, dividing the luminescent epitaxial structure into a series of luminescent units, and adhering the series of luminescent units to the expandable support film 290 to expand the film, so as to expand the spacing between the luminescent units, as shown in fig. 18, in this embodiment, the cutting may be performed in a laser stealth matching splitting manner; as shown in fig. 19, a photoresist layer 291 is formed on the electrode spacer, the photoresist layer being formed on the top surface of the light emitting cell and between the gaps of the adjacent light emitting cells; as shown in fig. 20, a first electrode 241 and a second electrode 242 are fabricated, which, in addition to covering the surface of the insulating layer 230, also fill the gap between the periphery of the light emitting unit and the photoresist layer 291, and finally the support film is removed, so as to form a series of independent LED chips as shown in fig. 21 and 22, where the first electrode and the second electrode cover the side wall of the LED chip and extend to the periphery of the side wall of the LED chip, thereby breaking the limitation of the small-sized LED chip on the size of the electrodes.
Preferably, the first electrode 230 and the second electrode 230 include a multi-layer structure, the bottom layer of the electrode is one or more stacked layers of Cr, Al, Ti, Ni, Pt, Au, and the like, and the surface layer of the electrode is a Sn-containing or Au-containing metal material, such as Sn, SnAgCu, SnAu, Au, CuAu alloy. In this embodiment, the electrode pad can be directly attached to the carrier substrate by vapor deposition or electroplating, and the electrode covers the side wall of the LED chip and extends to the periphery of the side wall of the LED chip, so as to effectively solve the problem of poor contact caused by insufficient solder in packaging due to small electrode area of the small-sized LED chip. Preferably, the minimum pitch between the first electrode and the second electrode is 15 μm or more, and the sidewall thickness W2 of the first electrode and the second electrode is preferably 10 μm or more, and may be 15 to 100 μm, for example.
EXAMPLE five
FIGS. 23-25 illustrate yet another flip-chip LED chip in accordance with the present invention. The LED chip comprises the following stacked layers: a transparent substrate 210, a light emitting mesa including a light emitting epitaxial stack and an insulating layer 230 covering a surface of the light emitting epitaxial stack, a first electrode 241 and a second electrode 242. Further, a support layer 231 is formed at the outer periphery of the transparent substrate 210, the support layer 231 covers the sidewall 210C of the transparent substrate 210 and the sidewall of the light emitting mesa, and has a first surface 231A and a second surface 231B, and a sidewall connecting the first surface 231A and the second surface 231B, wherein the first surface 231A is substantially flush with the surface 230A of the insulating layer 230 located on the second conductivity type semiconductor layer, and the second surface 231B is flush with the second surface 210B of the transparent substrate, so as to form a plane extending outward from the outer periphery of the light emitting mesa, the cross-sectional area of the plane is larger than that of the light emitting mesa, and the first electrode 241 and the second electrode 242 are formed on the plane, so as to increase the electrode area of the LED chip, thereby enlarging the die bonding window of the package terminal. Referring to fig. 14, L1 to L3 respectively indicate an edge of a light emitting mesa, an edge of a transparent substrate 210, and an edge of a supporting layer 231, a blank area in the middle of the drawing is a planar area on the light emitting mesa, an area filled with oblique lines is the supporting layer 231, a cutting street with a certain width is reserved for a cutting process such as laser stealth cutting and splitting in a manufacturing process of a light emitting diode, the cutting street is processed by the cutting process to form a second area of the first surface of the transparent substrate 210 around a light emitting epitaxial lamination, i.e., an area between L1 and L2, a width W4 of the cutting street is usually 10 to 50 μm, in this embodiment, the planar area on the electrode side of an LED chip is expanded outside the light emitting mesa by the supporting layer 231, the cutting street area of the transparent substrate 210 can be fully utilized to manufacture a planar electrode, and the problem of limited electrode area of a small-sized flip-. Particularly, for a small-sized flip-chip LED chip, for example, an LED chip with a size of 120 μm × 80 μm or smaller, the ratio of the area of the dicing street region to the cross-sectional area of the chip is large, the support layer 231 fully utilizes the dicing street region to heighten and extend the dicing street region beyond the edge of the transparent substrate, so as to obtain an enough planar electrode, ensure the electrode surface area of the small-sized flip-chip LED chip, and solve the problem of electrical short circuit caused by solder paste overflow due to a small area in the packaging process caused by a too small electrode.
For a particle having a diameter of about 62500 μm2The LED chip of a small size having a horizontal cross-sectional area of 230 μm × 120 μm, or 120 μm × 80 μm, or 100 μm × 60 μm, or 50 μm × 40 μm, for example, may be used, and the distance W3 from the edge L3 of the support layer 231 to the edge L2 of the transparent substrate is preferably 2 to 20 μm, for example, 5 to 10 μm.
The material of the support layer 231 may be SiO2、Al2O3、Ti3O5、SiNxThe insulating material may be formed by curing materials such as epoxy resin, silicone, and photoresist, and a material having excellent heat dissipation properties may be used.
The first electrode 241 and the second electrode 242 are formed on the surface 231A of the insulating layer 230 and the supporting layer 231. Preferably, the first and second electrodes may include a multilayer structure. In some embodiments, the electrode material is a combination of metals such as Cr, Pt, Au, Ti, Ni, Al, etc., and the surface layer is an Au material. In other embodiments, the bottom electrode layer is one or more of Cr, Al, Ti, Ni, Pt, Au, and the like, and the top electrode layer is a Sn-containing metal material, such as Sn, SnAgCu, SnAu. In this embodiment, the LED chip may be formed by evaporation or electroplating, and the electrode pad may be directly attached and soldered on the carrier substrate.
In some embodiments, the support layer may completely cover the outer periphery of the transparent substrate, as shown in fig. 25, in which fig. 24 is a plan view of one side of the transparent substrate, and fig. 25 is a plan view of one side of the electrode. Because the supporting layer completely covers the sidewalls of the LED chip, when the supporting layer 231 is made of a non-light-transmitting material, such as a reflective material or a light-absorbing material, the sidewalls can be ensured not to emit light, so that the light-emitting angle of the LED chip is reduced, the light-emitting angle can reach 135 ° or less, and the LED chip has high directivity. In one embodiment, the LED chip is applied to RGB display, and the supporting layer 231 is preferably made of black material, so that high contrast effect can be achieved.
The following describes the manufacturing process of the LED chip of this embodiment in detail.
Firstly, the epitaxial lamination of the light-emitting epitaxial structure is subjected to a simplification treatment to form a series of light-emitting table surfaces. Specifically, a scribe line and an electrode region are defined on the light emitting epitaxial structure shown in fig. 5 according to the size of the LED chip, a hole 270 is formed by etching the second conductive type semiconductor layer 223 and the active layer 222 of the electrode region through one or more photomasks, the hole 270 exposes a portion of the surface of the first conductive type semiconductor layer 221, and the second conductive type semiconductor layer 223, the active layer 222, and the first conductive type semiconductor layer 221 of the scribe line region are etched to form a trench 280. Further, a contact electrode 250 and an insulating layer 230 may be sequentially formed on the second conductive type semiconductor layer 223, the top surface and the sidewall of the light emitting epitaxial stack not covered by the contact electrode 250 and the contact electrode 250 are all covered by the insulating layer 230, a first opening 271 is formed in the first electrode electrical connection region of the first conductive type semiconductor layer 221, and a second opening 272 is formed in the surface of the contact electrode 250, as shown in fig. 26.
Next, the thickness of the transparent substrate 210 is reduced by polishing or the like as necessary, as shown in fig. 27.
Next, the transparent substrate 210 is cut along the cutting streets 280, the luminescent epitaxial structure is divided into a series of luminescent units, and the series of luminescent units are adhered to the expandable support film 290 to expand the film, so as to expand the spacing between the luminescent units, as shown in fig. 28, in this embodiment, the cutting may be performed by laser stealth matching splitting.
Next, a material layer is filled between the respective light emitting cells as a support layer 231, as shown in fig. 29. Preferably, the surface 231A of the support layer is flush with the surface of the insulating layer 230, thereby forming a flat surface on the light emitting epitaxial stack and the periphery.
Next, a first electrode 241 and a second electrode 242 are formed on the plane, wherein the first electrode 241 is electrically contacted to the first conductive type semiconductor layer 221 through the first opening 271, and the second electrode 242 is electrically contacted to the contact electrode 250 through the second opening. The first electrode 241 and the second electrode 242 are extended to the outer periphery of the light emitting epitaxial stack, as shown in fig. 30.
Finally, the above structure is singulated by etching or the like to form a series of flip-chip LED chips as shown in fig. 23. In this embodiment, the singulation process is preferably performed by laser etching.
In this embodiment, a supporting layer 231 is formed on the periphery of the transparent substrate after singulation, and the supporting layer 231 can provide more planar areas for making electrodes on one hand and easily obtain regular cutting edges on the other hand, so as to obtain LED chips with regular shapes and uniform sizes.
The foregoing embodiments are merely illustrative of the principles of this invention and its efficacy, rather than limiting it, and various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the invention, which is defined in the appended claims.

Claims (13)

1. A light emitting diode, comprising:
the transparent substrate is provided with a first surface, a second surface and a side wall, wherein the first surface and the second surface are opposite, and the side wall is connected with the first surface and the second surface;
the light-emitting table top is formed on the first surface of the transparent substrate and comprises a light-emitting epitaxial lamination layer, and the light-emitting epitaxial lamination layer is formed by stacking a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer from the first surface of the transparent substrate;
the supporting layer is formed at the periphery of the light-emitting epitaxial lamination layer and forms a plane with the light-emitting table top, and the cross sectional area of the plane is not lower than that of the first surface of the transparent substrate;
a first electrode disposed on the plane and electrically connected to the first conductive type semiconductor layer;
and a second electrode disposed on the plane and electrically connected to the second conductive type semiconductor layer.
2. The led of claim 1, wherein: the light emitting mesa includes an insulating layer covering at least an upper surface and a sidewall of the light emitting epitaxial stack and having a first opening through which the first electrode is electrically connected to the first conductive type semiconductor layer and a second opening through which the second electrode is electrically connected to the second conductive type semiconductor layer.
3. The led of claim 2, wherein: the insulating layer is an insulating layer, and the supporting layer is a colored material layer.
4. The light-emitting diode according to claim 3, wherein: the supporting layer is made of black glue.
5. The led of claim 2, wherein: the supporting layer is provided with a third surface which is flush with the surface of the insulating layer to form the plane.
6. The led of claim 1, wherein: the support layer at least partially covers the sidewalls of the transparent substrate.
7. The light-emitting diode of claim 6, wherein: the supporting layer is provided with a fourth surface which is flush with the second surface of the transparent substrate.
8. The light-emitting diode of claim 6, wherein: the supporting layer covers the side wall of the transparent substrate, and the thickness of the supporting layer is 2-20 mu m.
9. The led of claim 1, wherein: the first electrode and the second electrode are of a multilayer structure, the bottom layer is one or a combination of a plurality of layers of Cr, Al, Ti, Ni, Pt and Au metal materials, and the surface layer is made of Sn or Au metal materials.
10. The led of claim 1, wherein: the edge length of the first surface of the transparent substrate is between 200 to 300 μm, or 100 to 200 μm, or 40 to 100 μm.
11. The led of claim 1, wherein: the light emitted by the active layer is emitted from the second surface of the transparent substrate, and the light-emitting angle of the light is below 135 degrees.
12. The manufacturing method of the light-emitting diode is characterized by comprising the following steps of:
forming a light emitting mesa on a first surface of a transparent substrate, the light emitting mesa including a light emitting epitaxial stack of a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer stacked from the first surface of the transparent substrate;
(II) manufacturing a supporting layer which is formed at the periphery of the light-emitting epitaxial lamination layer and forms a plane with the light-emitting table top, wherein the cross sectional area of the plane is not less than that of the first surface of the transparent substrate;
(iii) fabricating a first electrode and a second electrode on the plane, wherein the first electrode is electrically connected to the first conductive type semiconductor layer; the second electrode is electrically connected to the second conductive type semiconductor layer.
13. The method of claim 12, wherein the step (one) further comprises:
(1) providing an epitaxial structure comprising a transparent substrate and a light-emitting epitaxial stack, the substrate having a first surface and a second surface, and sidewalls connecting the first surface and the second surface, the light-emitting epitaxial stack being formed on the first surface of the transparent substrate and comprising a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer stacked from the first surface of the transparent substrate;
(2) defining a cutting channel on the surface of the light-emitting epitaxial lamination, and dividing the epitaxial structure into a series of light-emitting units along the cutting channel;
(3) expanding the spacing between the series of light-emitting units;
and (b) a filling material layer between the light-emitting units in the step (two), wherein the filling material layer covers the side walls of the light-emitting units to form the support layer.
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