CN108470801B - LED core particle and manufacturing method thereof - Google Patents
LED core particle and manufacturing method thereof Download PDFInfo
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- CN108470801B CN108470801B CN201810234070.1A CN201810234070A CN108470801B CN 108470801 B CN108470801 B CN 108470801B CN 201810234070 A CN201810234070 A CN 201810234070A CN 108470801 B CN108470801 B CN 108470801B
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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
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- H01L33/0093—Wafer bonding; Removal of the growth substrate
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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
- H01L33/44—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 coatings, e.g. passivation layer or anti-reflective coating
Abstract
The embodiment of the invention discloses a manufacturing method of an LED core grain, which comprises the steps of forming a first cutting seam penetrating and cutting a PN junction structure before a first metal bonding structure is ablated by a laser scribing process, then forming a first protective layer on the surface of the first cutting seam to form a protective layer on the side wall of the LED core grain, and forming a second cutting seam penetrating through a current spreading layer in the first cutting seam to reduce a fusant generated in the subsequent laser scribing process, reduce the absorption of the fusant on emergent rays of the side wall of the LED core grain in the direction of the side wall, and improve the luminous efficiency of the LED core grain.
Description
Technical Field
The invention relates to the technical field of LEDs, in particular to an LED core particle and a manufacturing method thereof.
Background
A Light Emitting Diode (LED) is a kind of semiconductor Diode, which can convert electric energy into Light energy to emit visible Light of various colors such as red, yellow, green, blue, etc., and invisible Light of infrared and ultraviolet, and has the advantages of low working voltage and current, high reliability, long service life, etc. Among them, the quaternary system LED chip has been widely applied to various fields such as large screen display, traffic signal lamp, landscape lighting, and automobile status display lamp due to its high luminous efficiency, wide color range, and long service life.
Specifically, when a quaternary system LED chip is manufactured, an LED wafer including a plurality of quaternary system LED dies is usually manufactured first, and then a cutting method is used to cut the whole LED wafer into single quaternary system LED die, but when the quaternary system LED wafer formed by a substrate transfer and metal bonding process is cut into single quaternary system LED die in the conventional manufacturing method, the quaternary system LED die has a phenomenon of a decrease in light emission efficiency (the light emission efficiency of the chip is detected before and after laser scribing to evaluate the influence caused by the laser scribing).
Disclosure of Invention
In order to solve the above technical problems, embodiments of the present invention provide an LED core particle and a manufacturing method thereof, so as to improve the light emitting efficiency of the LED core particle.
In order to solve the above problems, the embodiments of the present invention provide the following technical solutions:
a method for manufacturing an LED core particle comprises the following steps:
fabricating a first semiconductor structure, the first semiconductor structure comprising: the epitaxial structure comprises an etching stop layer positioned on the surface of the first substrate, an ohmic contact layer positioned on the surface of the etching stop layer, a PN junction structure positioned on the surface of the ohmic contact layer and a current expansion layer positioned on the surface of the PN junction structure, wherein the reflecting structure comprises a first dielectric layer positioned on the surface of the current expansion layer and a first metal layer positioned on the surface of the first dielectric layer;
forming a first metal bonding structure on the surface of the reflecting structure;
manufacturing a second semiconductor structure, wherein the second semiconductor structure comprises a second substrate;
bonding the first semiconductor structure and the second semiconductor structure using the first metal bonding structure;
removing partial areas of the first substrate, the etch stop layer in the epitaxial structure and the ohmic contact layer, reserving the partial areas, and forming at least one ohmic contact pattern in a plurality of preset areas on the surface of the PN junction structure, wherein the preset areas correspond to the LED core particles to be manufactured one by one;
forming a bonding pad in the preset area, wherein the bonding pad completely covers the ohmic contact pattern of the preset area;
cutting the epitaxial structure from the side of the pad, and forming a first cutting seam between any two adjacent preset areas in the plurality of preset areas, wherein the first cutting seam completely penetrates through the PN junction structure and does not expose the first metal layer;
forming a first protective layer on the surface of the first cutting seam;
forming a second cutting seam in the area where the first cutting seam is located, wherein the second cutting seam penetrates through the first medium layer at most, and the width of the second cutting seam is smaller than that of the first cutting seam;
forming a third cutting seam in the area where the second cutting seam is located by utilizing a laser scribing process, wherein the third cutting seam completely penetrates through the first metal bonding structure and extends into the second substrate;
and cutting a fourth cutting seam from the side of the second substrate, which is far away from the first metal bonding structure, until the fourth cutting seam is communicated with the third cutting seam, so as to form a plurality of independent LED core particles.
Optionally, forming an epitaxial structure on the first substrate further includes: and forming a first limiting layer between the ohmic contact layer and the PN junction structure.
Optionally, forming an epitaxial structure on the first substrate further includes:
a second confinement layer is formed between the current spreading layer and the PN junction structure.
Optionally, forming an epitaxial structure on the first substrate further includes: forming a roughened layer between the ohmic contact layer and the first confinement layer;
before forming the first protective layer on the first kerf surface, the method further comprises: and carrying out roughening treatment on the surface of one side of the roughened layer, which is far away from the first limiting layer, so that the side of the roughened layer, which is far away from the first limiting layer, is a rough surface.
Optionally, the forming a reflective structure on a side of the epitaxial structure facing away from the first substrate includes:
forming a first medium layer on the surface of one side, away from the first substrate, of the epitaxial structure, wherein the first medium layer is provided with a plurality of contact holes;
and forming a first metal layer on the surface of one side, away from the epitaxial structure, of the first dielectric layer and in the contact hole, and heating and fusing the first metal layer at a first preset temperature for a first preset time.
Optionally, the width of the first cutting slit ranges from 20 micrometers to 50 micrometers, inclusive; the depth of the first cutting peak ranges from 4 microns to 10 microns, inclusive.
Optionally, forming a second dicing seam in a region where the first dicing seam is located, where the second dicing seam exposes the first metal bonding structure portion region, includes:
and forming a second cutting seam in the area where the first cutting seam is located by utilizing an ICP (inductively coupled plasma) dry etching process or a chemical wet etching process, wherein the second cutting seam takes the fact that the second cutting seam completely penetrates through the current expansion layer as the standard, so that the second cutting seam exposes a part of the area of the first metal bonding structure.
Optionally, the width of the second cutting seam ranges from 10 micrometers to 40 micrometers, inclusive.
An LED core particle manufactured by the manufacturing method of any one of the above, comprising:
a second substrate;
the metal bonding structure is positioned on the surface of the second substrate and comprises a first metal bonding structure;
the reflecting structure is positioned on one side, away from the second substrate, of the metal bonding structure and comprises a first metal layer positioned on the surface of the metal bonding structure and a first dielectric layer positioned on the surface of the first metal layer;
an epitaxial structure on a side of the reflective structure facing away from the metal bond structure, the epitaxial structure comprising: the metal bonding structure comprises a current spreading layer, a PN junction structure and an ohmic contact pattern, wherein the current spreading layer is positioned on one side of the reflecting structure, which is far away from the metal bonding structure;
the bonding pad is positioned on one side, away from the PN junction structure, of the ohmic contact pattern and is electrically connected with the ohmic contact pattern;
in the preset direction X, the width of the PN junction structure is smaller than that of the current spreading layer and than that of the metal bonding structure.
Optionally, the epitaxial structure further includes:
a first confinement layer positioned between the PN junction structure and the ohmic contact pattern; and/or the presence of a gas in the gas,
a second confinement layer located between the PN junction structure and the current spreading layer.
Compared with the prior art, the technical scheme has the following advantages:
according to the manufacturing method of the LED core grain provided by the embodiment of the invention, before the first metal bonding structure is ablated by using a laser scribing process, the first cutting slit penetrating and cutting the PN junction structure is formed, then the first protective layer is formed on the surface of the first cutting slit to form the protective layer on the side wall of the LED core grain, and the second cutting slit penetrating through the current spreading layer is formed in the first cutting slit to reduce the fusant generated in the subsequent laser scribing process, reduce the absorption of the fusant on the emergent light of the LED core grain, and improve the luminous efficiency of the LED core grain.
In addition, according to the manufacturing method of the LED core particle provided by the embodiment of the invention, when the second cutting seam is formed, since the surface of the first cutting seam is protected by the first protection layer, even if the second cutting seam contacts the first metal bonding structure during etching to generate a part of melt, the melt does not adhere to the PN junction sidewall of the LED core particle, so that the LED core particle is prevented from being electrically leaked.
In summary, the light emitting from the side wall of the core particle of the LED chip manufactured by the method of the present invention can be significantly improved, so that the overall light emitting efficiency of the core particle is improved by 8% to 10%, the leakage phenomenon is also significantly reduced, and the yield is improved by 1% to 2%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flow chart of a method for fabricating an LED core particle according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a first semiconductor structure in a method for manufacturing an LED core particle according to an embodiment of the present invention;
fig. 3 is a schematic layout diagram of contact holes on an LED chip in a method for manufacturing an LED core particle according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an ohmic contact pattern in a method for fabricating an LED core particle according to an embodiment of the present invention;
FIG. 5 is a top view of a bonding pad in a method of fabricating an LED die according to an embodiment of the invention;
fig. 6 is a top view of a first cutting slit in a method for making an LED core particle according to an embodiment of the present invention;
FIG. 7 is a cross-sectional view of the first slit of FIG. 6;
fig. 8 is a top view of a first protective layer on the surface of a first slit in a method for manufacturing an LED core particle according to an embodiment of the present invention;
FIG. 9 is a cross-sectional view of the first protective layer shown in FIG. 8;
FIG. 10 is a top view of a second protective layer in a method of fabricating an LED core die according to one embodiment of the present invention;
fig. 11 is a top view of a second dicing line in a method of manufacturing an LED core particle according to an embodiment of the present invention;
FIG. 12 is a cross-sectional view of the second cutting seam shown in FIG. 11;
fig. 13 is a cross-sectional view of a third cut in a method of fabricating an LED core die according to an embodiment of the present invention;
fig. 14 is a schematic structural diagram of an LED core particle according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
As described in the background section, in the conventional cutting method, after a quaternary system LED wafer formed by using a substrate transfer and metal bonding process is cut into single quaternary system LED core particles, the quaternary system LED core particles have a phenomenon of low light emitting efficiency.
The inventor researches and discovers that because the metal bonding layer is contained in the quaternary system LED wafer formed by adopting the substrate transfer and metal bonding processes, the metal bonding layer can be scratched and cracked only by adopting laser, when the whole quaternary system LED chip is cut into single quaternary system LED core particles, in the existing manufacturing method, cutting channels are firstly formed on the whole quaternary system LED chip so as to divide the area where each quaternary system LED core particle is located, and then the laser scribing process is utilized to scribe the middle of the cutting channels so as to form the single quaternary system LED core particles.
Due to the limitation of the process, the cutting street cannot be accurately stopped on the surface of the metal bonding layer, therefore, during specific cutting, the cutting street is usually formed on the LED chip, the cutting street extends to a certain area above the metal bonding layer, based on penetrating through a PN junction in the LED chip, and then the metal bonding layer and the area above the metal bonding layer are cut by using a laser scribing process, so that more high-temperature melts are generated during the laser scribing process and adhere to the side wall of the LED core grain, so that the side wall of the LED core grain is blocked from light emitting, and the light emitting efficiency is reduced.
In addition, black melts formed at the edges of the cutting channels during laser scribing are easy to adhere to PN junctions of the LED core particles, so that the LED core particles have a current leakage phenomenon.
In view of this, an embodiment of the present invention provides a method for manufacturing an LED core particle, as shown in fig. 1, the method includes:
s1: fabricating a first semiconductor structure, as shown in fig. 2, the first semiconductor structure comprising: the epitaxial structure comprises a first substrate 10, an epitaxial structure 20 positioned on the surface of the first substrate 10, and a reflecting structure 30 positioned on the surface of the epitaxial structure 20, wherein the first substrate 10 is a gallium arsenide substrate, and the epitaxial structure 20 comprises an etch stop layer 21 positioned on the surface of the first substrate 10, an ohmic contact layer 22 positioned on the surface of the etch stop layer 21, a PN junction structure 23 positioned on the surface of the ohmic contact layer 22, and a current spreading layer 24 positioned on the surface of the PN junction structure 23. The etching stop layer 21 is used as a stop layer in a subsequent etching process, the ohmic contact layer 22 is used for electrically connecting the PN junction structure 23 and a pad formed subsequently, the PN junction structure 23 is used for generating emergent light of the LED, the current spreading layer 24 is used for improving current conduction efficiency, and the reflection structure 30 is used for reflecting the light emitted by the PN junction structure 23 to one side of the current spreading layer 24 back to one side of the ohmic contact layer 22 so as to improve the light emitting amount of the light of the LED chip from one side of the ohmic contact layer 22.
Specifically, on the basis of the above embodiment, in an embodiment of the present invention, the fabricating the first semiconductor structure includes: providing a first substrate, wherein the first substrate is a gallium arsenide substrate; forming an epitaxial structure on the first substrate; and forming a reflecting structure on the side of the epitaxial structure, which is far away from the first substrate. Optionally, the process of forming the epitaxial structure is MOCVD (Metal-organic Chemical Vapor Deposition), but the present invention is not limited thereto, and in other embodiments of the present invention, the process of forming the epitaxial structure may also be other Deposition processes, as the case may be.
Optionally, on the basis of the foregoing embodiment, in an embodiment of the present invention, the epitaxial structure includes: an N-GaInP etch stop layer on the surface of the first substrate; the N-GaAs ohmic contact layer is positioned on one side, away from the first substrate, of the N-GaInP corrosion stop layer; the PN junction structure is positioned on one side, away from the N-GaInP corrosion stop layer, of the N-GaAs ohmic contact layer; and the current spreading layer is positioned on one side of the PN junction structure, which is far away from the N-GaAs ohmic contact layer. Accordingly, forming an epitaxial structure on the first substrate includes:
forming an N-GaInP corrosion stop layer on the surface of the first substrate; forming an N-GaAs ohmic contact layer on the surface of the N-GaInP corrosion stop layer on the side opposite to the first substrate; forming a PN junction structure on the surface of one side of the N-GaAs ohmic contact layer, which is far away from the N-GaInP corrosion stop layer; and forming a current spreading layer on the surface of one side of the PN junction structure, which is far away from the N-GaAs ohmic contact layer.
In the above embodiment, the current spreading layer is a P-GaP current spreading layer; continuing with fig. 2, the PN junction structure comprises: the N-type waveguide layer (namely the N-Space waveguide layer) is positioned on one side, away from the N-GaInP corrosion stop layer, of the N-GaAs ohmic contact layer; a MQW (Multiple Quantum well) active region on the side of the N-type waveguide layer facing away from the ohmic contact layer; and the P-type waveguide layer (namely, the P-Space waveguide layer) is positioned on one side of the MQW active region, which is far away from the N-type waveguide layer. In specific operation, electrons in the N-type waveguide layer and holes in the P-type waveguide layer both move towards the MQW active region and recombine in the MQW active region to generate LED light.
Optionally, on the basis of any of the above embodiments, in an embodiment of the present invention, in order to prevent electrons in the N-type waveguide layer from moving to a side away from the MQW active region, as shown in fig. 2, the epitaxial structure 20 further includes: and a first confinement layer 25 located between the ohmic contact layer 22 and the PN junction structure 23, specifically, when the ohmic contact layer is an N-GaAs ohmic contact layer, the first confinement layer is an N-type confinement layer. Accordingly, forming an epitaxial structure on the first substrate further comprises: and forming a first limiting layer between the ohmic contact layer and the PN junction structure.
Similarly, on the basis of any of the above embodiments, in an embodiment of the present invention, in order to prevent the holes in the P-type waveguide layer from moving to the side away from the MQW active region, as shown in fig. 2, the epitaxial structure 20 further includes: and a second confinement layer 26 located between the current spreading layer 24 and the PN junction structure 23, specifically, when the current spreading layer is a P-GaP current spreading layer, the second confinement layer is a P-type confinement layer. Accordingly, forming an epitaxial structure on the first substrate further comprises: a second confinement layer is formed between the current spreading layer and the PN junction structure.
On the basis of any of the above embodiments, in an embodiment of the present invention, in order to reduce the proportion of total reflection when the light of the PN junction structure is emitted from the ohmic contact layer side to the air interface, and increase the light output amount of the LED chip, as shown in fig. 2, the epitaxial structure 20 further includes: and the roughened layer 27 is positioned between the first limiting layer 25 and the ohmic contact layer 22, and the surface of one side, away from the first limiting layer 25, of the roughened layer 27 is a roughened surface. Accordingly, forming an epitaxial structure on the first substrate further comprises: forming a roughened layer between the ohmic contact layer and the first confinement layer; and subsequently, roughening the surface of one side of the roughened layer, which is far away from the first limiting layer, so that the surface of one side of the roughened layer, which is far away from the first limiting layer, is a rough surface.
Specifically, in one embodiment of the present invention, when the ohmic contact layer is an N-GaAs ohmic contact layer and the first confinement layer is an N-type confinement layer, the roughened layer is an N-AlGaInP roughened layer.
Optionally, on the basis of any one of the above embodiments, in a specific embodiment of the present invention, a total thickness of the epitaxial structure ranges from 5 μm to 15 μm, inclusive; the thickness of the coarsening layer is 2-4 μm so as to ensure the coarsening effect of the coarsening layer; the thickness of the current spreading layer ranges from 1 μm to 3 μm, so as to avoid that the current spreading layer is too thin and affects the spreading effect of the current spreading layer, and avoid that the current spreading layer is too thick and absorbs too much light and affects the light output and the light emitting efficiency of the LED core particles.
On the basis of any one of the foregoing embodiments, in an embodiment of the present invention, the forming a reflective structure on a side of the epitaxial structure facing away from the first substrate includes: forming a first medium layer on the surface of one side, away from the first substrate, of the epitaxial structure, wherein the first medium layer is provided with a plurality of contact holes; and forming a first metal layer on the surface of one side of the first dielectric layer, which is far away from the epitaxial structure, and in the contact hole, and heating and fusing for a first preset time at a first preset temperature, so that the part, which is positioned in the contact hole, of the first metal layer can be in good ohmic contact with the current expansion layer. As shown in fig. 3, fig. 3 is a schematic diagram illustrating the arrangement of the contact holes a in the first dielectric layer when the size of the LED core particle is a square of 5.5mil (137.5 micrometers), which is not limited in the present invention, and the size, number and arrangement position of the contact holes in the first dielectric layer are determined by the spreading effect of the current spreading layer, the size of the contact holes, and the reflection effect of the reflection structure.
In another embodiment of the present invention, the LED core particle may have a square shape or a rectangular shape, and the size thereof may be 5.5mil, or other values such as 6mil or 8mil, as the case may be.
On the basis of the above embodiments, in an embodiment of the present invention, the first preset temperature is in a range of 300 ℃ to 500 ℃, inclusive, and preferably 460 ℃; the first preset time is 10 minutes to 30 minutes, inclusive, preferably 15 minutes, but the present invention is not limited thereto, as the case may be.
It should be noted that, in the embodiment of the present invention, the reflecting structure is preferably an omnidirectional reflector, and the present invention is not limited to this, as the case may be. Specifically, in an embodiment of the present invention, a refractive index of the first dielectric layer ranges from 1.4 to 2.2, including end values, such as a silicon dioxide layer, a silicon nitride layer, and the like, to ensure a reflection effect of the first dielectric layer, and the first metal layer is a metal layer with a reflection effect, such as a gold layer, a silver layer, an aluminum layer, and the like, to ensure a reflection effect of the first metal layer.
Optionally, on the basis of the above embodiment, in an embodiment of the present invention, a forming process of the first dielectric layer is PECVD (Plasma Enhanced Chemical Vapor Deposition), and the thickness is 106 nm; the forming process of the contact hole is photoetching and wet etching; the first metal layer is a laminated Au layer, an AuZn layer and an Au layer, and the thickness of the first metal layer is 100nm to 300nm, including an endpoint value, preferably 300nm, but the invention is not limited thereto, and is determined as the case may be.
On the basis of any one of the above embodiments, in an embodiment of the present invention, before forming a reflective structure on a side of the epitaxial structure facing away from the first substrate, the method further includes: and cleaning the epitaxial structure to remove impurities on the surface of the epitaxial structure. Optionally, the cleaning the epitaxial structure includes: the epitaxial structure is subjected to organic cleaning, preferably, the epitaxial structure is subjected to organic cleaning by using acetone, but the present invention is not limited thereto, and in other embodiments of the present invention, other cleaning manners and/or other cleaning agents may also be used for cleaning the epitaxial structure, as the case may be.
S2: and forming a first metal bonding structure on the surface of the reflecting structure.
Specifically, in an embodiment of the present invention, the first metal bonding structure is an Au layer with a thickness of 6 μm, but the present invention is not limited thereto, as the case may be.
S3: and manufacturing a second semiconductor structure, wherein the second semiconductor structure comprises a second substrate. Optionally, the second substrate is a silicon substrate, but the invention is not limited thereto, as the case may be.
In one embodiment of the present invention, the second semiconductor structure includes only a second substrate; in another embodiment of the present invention, the second semiconductor structure includes: the second metal bonding structure is an Au layer, but the invention is not limited to this, and the second metal bonding structure is located on the surface of the second substrate.
S4: and bonding the first semiconductor structure and the second semiconductor structure by using the first metal bonding structure.
It should be noted that, in the embodiment of the present invention, before bonding the first semiconductor structure and the second semiconductor structure by using the first metal bonding structure, the method further includes: and polishing the second substrate and cleaning the second semiconductor structure to remove impurities on the surface of the second semiconductor structure. And then bonding the first semiconductor structure and the second semiconductor structure by using a bonding machine.
Optionally, in an embodiment of the present invention, the second semiconductor structure is cleaned by using an organic cleaning agent, and the cleaning agent is acetone, but the present invention is not limited thereto, as the case may be.
S5: and removing partial areas of the first substrate, the etch stop layer in the epitaxial structure and the ohmic contact layer, reserving the partial areas, and forming at least one ohmic contact pattern in a plurality of preset areas on the surface of the PN junction structure, wherein the preset areas correspond to the LED core particles to be manufactured one by one.
Specifically, in an embodiment of the present invention, removing a partial region of the first substrate, the etch stop layer in the epitaxial structure, and the ohmic contact layer, and leaving a partial region, and forming at least one ohmic contact pattern in a plurality of predetermined regions on the surface of the PN junction structure includes:
removing the first substrate and the etching stop layer in the epitaxial structure by using a wet etching process;
and removing partial area of the ohmic contact layer by utilizing a photoetching process, and forming at least one ohmic contact pattern in a plurality of preset areas on the surface of the PN junction structure.
It should be noted that the ohmic contact pattern may be a point, a straight line, a ring, or another pattern, and the present invention is not limited to this, and specifically, as long as the ratio of the area occupied by the at least one ohmic contact pattern in the preset region to the area of the preset region is ensured to be 1% to 3%, including the end point value, so as to prevent the area occupied by the ohmic contact pattern in the preset region from being small and affecting the ohmic contact effect, and simultaneously prevent the area occupied by the ohmic contact pattern in the preset region from being large and absorbing light more and affecting the light output amount of the LED core particle.
As shown in fig. 4, fig. 4 is a plan view of the LED chip including four LED core particles, and the ohmic contact pattern B is in the form of a circular ring. Wherein the inner diameter radius of the ohmic contact pattern B is 26 micrometers, and the outer diameter radius thereof is 31 micrometers.
S6: and forming a bonding pad in the preset area, wherein the bonding pad completely covers the ohmic contact pattern of the preset area.
In one embodiment of the present invention, forming a pad in the predetermined region, wherein the ohmic contact pattern of the pad completely covering the predetermined region includes:
forming a metal covering layer on one side of the ohmic contact pattern, which is far away from the PN junction structure, wherein the metal covering layer completely covers the ohmic contact pattern and at least covers part of the PN junction structure;
and removing partial area of the metal covering layer by using a lift-off peeling method to form a pad C, wherein the pad C completely covers the ohmic contact pattern of the preset area where the pad is positioned, as shown in FIG. 5. Specifically, in one embodiment of the present invention, the bonding pad is a circular bonding pad with a radius of 36 μm, but the present invention is not limited thereto, as the case may be.
S7: and cutting the epitaxial structure from the side of the welding disc, and forming a first cutting seam between any two adjacent preset areas in the plurality of preset areas, wherein the first cutting seam completely penetrates through the PN junction structure and does not expose the first metal layer.
Specifically, in an embodiment of the present invention, the cutting the epitaxial structure from the pad side, and forming a first cutting seam between any two adjacent preset regions in the plurality of preset regions, where the first cutting seam completely penetrates through the PN junction structure and does not expose the first metal layer includes:
etching the epitaxial structure from the side of the pad by using an ICP (inductively Coupled Plasma) dry etching or a chemical wet etching process, and forming a first cutting slit D between any two adjacent preset regions in the plurality of preset regions, as shown in fig. 6 and 7, where the first cutting slit D completely penetrates through the PN junction structure and does not expose the first metal layer. The etching solution of the chemical wet etching process may be a mixed solution of phosphoric acid and hydrogen peroxide or other etching solutions, which is not limited in the present invention and is determined as the case may be.
Specifically, in an embodiment of the present invention, the width of the first cutting slit ranges from 20 micrometers to 50 micrometers, inclusive, and is optionally 34 micrometers; the depth of the first cutting peak ranges from 5 micrometers to 10 micrometers inclusive; the value range of the ICP etching time is 100s-300s, including an end point value, the invention is not limited to this, and particularly, the phenomenon that the LED core particles generate electric leakage due to by-products when the first cutting slit penetrates through the current limiting layer and contacts the first metal layer is avoided on the basis that the first cutting slit does not penetrate through the current limiting layer.
S8: and forming a first protective layer on the surface of the first cutting seam. The first slit surface at least includes a first slit sidewall, and may also include the first slit bottom, which is not limited in the present invention as long as the first slit sidewall is included.
Specifically, in an embodiment of the present invention, the forming a first protection layer on the surface of the first cut includes:
forming a protective covering layer on the surface of the first cutting seam and the surface of the epitaxial structure by utilizing PECVD;
and removing a partial region of the protective covering layer to form a first protective layer E, wherein the first protective layer E at least covers the surface of the first cutting seam, as shown in fig. 8 and 9, so as to protect the side wall of the LED core particle to be formed and the first cutting seam. Optionally, removing the partial region of the protective overcoat includes using NH4And F, removing part of the area of the protective covering layer by using the solution. However, the present invention is not limited thereto, as the case may be.
It should be noted that, in the embodiment of the present invention, a width of the first protection layer in a region between adjacent LED core particles may be equal to a width of the first cutting slit, or may be slightly greater than the width of the first cutting slit, which is not limited in the present invention, as long as the first protection layer completely covers a surface of the first cutting slit.
On the basis of the above embodiment, in a specific embodiment of the present invention, the first protection layer is a silicon nitride layer with a thickness of 500 angstroms, and the width of the first protection layer in the region between adjacent LED core particles is 38 micrometers, but the present invention is not limited thereto, as the case may be.
On the basis of any one of the above embodiments, in an embodiment of the present invention, when the epitaxial structure includes a roughened layer located between the first confinement layer and the ohmic contact layer, and a surface of the roughened layer on a side away from the first confinement layer is a rough surface, before the first protective layer is formed on the first cut seam surface, a surface of the roughened layer on a side away from the first confinement layer is roughened, so that a surface of the roughened layer on a side away from the first confinement layer is a rough surface. Specifically, in an embodiment of the present invention, roughening a surface of the roughened layer away from the first confinement layer so that the surface of the roughened layer away from the first confinement layer is a rough surface includes:
as shown in fig. 10, a second protective layer F is formed on a side of the pad facing away from the ohmic contact layer, where the second protective layer F completely covers the pad, the first cutting slit and the edge of the light emitting region of the LED core particle, and optionally, the process for forming the second protective layer is a photolithography process;
taking the second protection layer as a protection layer, and carrying out roughening treatment on the surface of the roughened layer, which is away from the first limiting layer, so that the surface of the roughened layer, which is away from the first limiting layer, is a rough surface;
and removing the second protective layer.
Specifically, on the basis of the above embodiment, in an embodiment of the present invention, the second protective layer includes a first protective region and a second protective region, wherein the first protective region is used for covering the first cutting slit and the edge of the light emitting region of the LED core particles, the width of the region between the adjacent LED core particles is 42 micrometers, the second protective region is used for covering the pad region, and the radius of the second protective region is 40 micrometers, but the present invention is not limited thereto, as long as it is ensured that the second protective layer can completely cover the pad, the edge of the light emitting region of the first cutting slit and the LED core particles. The second protective layer ensures that the bonding pad, the first cutting seam and the edge of the light emitting region of the LED core particle are completely covered, and the smaller the area is, the better the area is, so as to increase the rough area of the surface of the roughened layer on the side away from the PN junction structure.
S9: as shown in fig. 11 and 12, a second cutting seam G is formed in the area where the first cutting seam is located, the second cutting seam G penetrates through the first dielectric layer at most, and the width of the second cutting seam G is smaller than that of the first cutting seam.
Specifically, in an embodiment of the present invention, forming a second cutting seam in a region where the first cutting seam is located, where the second cutting seam penetrates through the first dielectric layer at most includes:
and forming a second cutting seam in the area of the first cutting seam by utilizing an ICP (inductively coupled plasma) dry etching process or a chemical wet etching process, wherein the second cutting seam completely penetrates through the first medium layer, so that the second cutting seam exposes the part of the first metal layer.
It should be noted that, in the embodiment of the present invention, the second dicing line may penetrate through the first dielectric layer and extend to the surface of the first metal layer, and may also penetrate through the current spreading layer and extend to the surface of the first dielectric layer.
Because ICP utilizes plasma to react with the material being processed to form gaseous products, the gaseous products are carried away by the exhaust system of the ICP processing apparatus and do not produce a melt. Therefore, the forming process of the first cutting seam and the second cutting seam is preferably an ICP dry etching process to reduce reaction products in the forming process of the first cutting seam and the second cutting seam.
It should be noted that the purpose of forming the second cutting seam is to remove the current spreading layer and the redundant first protection layer on the sidewall of the bottom of the first cutting seam, so as to reduce the source of the melt (such as the melt generated by laser ablation of the current spreading layer and the first dielectric layer) in the subsequent laser scribing process, so that the melt generated in the laser scribing process does not break through the first protection layer on the sidewall of the first cutting seam, reduce the amount of the melt generated in the laser ablation process adhering to the sidewall of the LED core particle, improve the light emitting efficiency of the LED core particle, and simultaneously avoid the melt generated in the laser ablation process contacting the PN junction structure of the LED core particle, so as to avoid the occurrence of the electrical leakage phenomenon.
Optionally, in the contact of the above embodiment, in an embodiment of the present invention, a width of the second dicing line ranges from 10 micrometers to 40 micrometers, inclusive, but the present invention is not limited thereto, as the case may be. Specifically, in one embodiment of the present invention, the width of the second dicing line is 22 μm.
S10: as shown in fig. 13, a third cutting seam H is formed in a region where the second cutting seam is located by using a laser scribing process, and the third cutting seam H completely penetrates through the first metal bonding structure 200 and extends into the second substrate 300, but the invention is not limited thereto, and the third cutting seam H completely penetrates through the first metal bonding structure 200 and extends at least to a surface of the second substrate 300 facing to a side of the first metal bonding structure 200.
Specifically, in an embodiment of the present invention, the width of the third cutting slit ranges from 8 micrometers to 15 micrometers inclusive, and the depth ranges from 20 micrometers to 50 micrometers inclusive.
S11: and cutting a fourth cutting seam from the side of the second substrate, which is far away from the first metal bonding structure, until the fourth cutting seam is communicated with the third cutting seam, so as to form a plurality of independent LED core particles, as shown in FIG. 14.
Specifically, in an embodiment of the present invention, the cutting a fourth dicing line from the side of the second substrate away from the first metal bonding structure until the fourth dicing line communicates with the third dicing line to form a plurality of individual LED core particles includes:
performing primary cutting of a fourth cutting seam on the second substrate from the side of the second substrate, which is far away from the first metal bonding structure, in a blade back scribing mode to realize pre-separation of the LED core particles;
and cutting the second substrate again at a fourth cutting seam from the side of the second substrate departing from the first metal bonding structure by adopting a splitting mode until the fourth cutting seam is communicated with the third cutting seam, so that the LED core particles are thoroughly separated, and a plurality of independent LED core particles are formed.
Accordingly, embodiments of the present invention also provide an LED core particle, as shown in fig. 14, which includes:
a second substrate 300; the metal bonding structure 400 is positioned on the surface of the second substrate 300, and the metal bonding structure 400 comprises a first metal bonding structure 200; a reflective structure 30 located on a side of the metal bond structure 400 facing away from the second substrate 300; an epitaxial structure 20 on a side of the reflective structure 30 facing away from the metal bond structure 400, the epitaxial structure 20 comprising: a current spreading layer 24 positioned on the side of the reflective structure 30 away from the metal bonding structure 400, and a PN junction structure 23 positioned on the side of the current spreading layer 24 away from the reflective structure 30; an ohmic contact pattern (not shown) on a side of the PN junction structure 23 facing away from the current spreading layer 24; a bonding pad C positioned on one side of the ohmic contact pattern, which is far away from the PN junction structure 23, wherein the bonding pad C is electrically connected with the ohmic contact pattern;
in the preset direction X, the width of the PN junction structure 23 is smaller than the width of the current spreading layer 24 is smaller than the width of the metal bonding structure 400.
It should be noted that, in the LED core particle provided in the embodiment of the present invention, the reason why the width of the PN junction structure 23 is smaller than the width of the current spreading layer 24 and smaller than the width of the metal bonding structure 400 is that, in the manufacturing process of the LED core particle, the width of the first cutting seam D is larger than the width of the second cutting seam G and is larger than the width of the third cutting seam H.
Optionally, on the basis of the above embodiment, in an embodiment of the present invention, the second substrate is a silicon substrate, but the present invention is not limited thereto.
It should be noted that, in the embodiment of the present invention, when the second semiconductor structure includes a second substrate and a second metal bonding structure located on a surface of the second substrate, the metal bonding structure 400 includes not only the first metal bonding structure 200 but also the second metal bonding structure; the present invention is not limited in this regard, as the case may be.
According to the manufacturing method of the LED core grain provided by the embodiment of the invention, before the first metal bonding structure is ablated by using a laser scribing process, the first cutting slit penetrating and cutting the PN junction structure is formed, then the first protective layer is formed on the surface of the first cutting slit to form the protective layer on the side wall of the LED core grain, and the second cutting slit penetrating through the current spreading layer is formed in the first cutting slit to reduce the fusant generated in the subsequent laser scribing process, reduce the absorption of the fusant on the emergent light of the LED core grain, and improve the luminous efficiency of the LED core grain.
In addition, according to the manufacturing method of the LED core particle provided by the embodiment of the invention, when the second cutting seam is formed, since the surface of the first cutting seam is protected by the first protection layer, even if the second cutting seam contacts the first metal bonding structure during etching to generate a part of melt, the melt does not adhere to the PN junction sidewall of the LED core particle, so that the LED core particle is prevented from being electrically leaked.
In summary, the light emitting from the side wall of the core particle of the LED chip manufactured by the method of the present invention can be significantly improved, so that the overall light emitting efficiency of the core particle can be improved by 8% to 10%, the leakage phenomenon can be significantly reduced, and the yield can be improved by 1% to 2%.
In the description, each part is described in a progressive manner, each part is emphasized to be different from other parts, and the same and similar parts among the parts are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for manufacturing an LED core particle is characterized by comprising the following steps:
fabricating a first semiconductor structure, the first semiconductor structure comprising: the epitaxial structure comprises an etching stop layer positioned on the surface of the first substrate, an ohmic contact layer positioned on the surface of the etching stop layer, a PN junction structure positioned on the surface of the ohmic contact layer and a current expansion layer positioned on the surface of the PN junction structure, wherein the reflecting structure comprises a first dielectric layer positioned on the surface of the current expansion layer and a first metal layer positioned on the surface of the first dielectric layer;
forming a first metal bonding structure on the surface of the reflecting structure;
manufacturing a second semiconductor structure, wherein the second semiconductor structure comprises a second substrate;
bonding the first semiconductor structure and the second semiconductor structure using the first metal bonding structure;
removing the first substrate and the corrosion stop layer in the epitaxial structure, removing partial areas of the ohmic contact layer, reserving the partial areas, and forming at least one ohmic contact pattern in a plurality of preset areas on the surface of the PN junction structure, wherein the preset areas correspond to the LED core particles to be manufactured one by one;
forming a bonding pad in the preset area, wherein the bonding pad completely covers the ohmic contact pattern of the preset area;
cutting the epitaxial structure from the side of the pad, and forming a first cutting seam between any two adjacent preset areas in the plurality of preset areas, wherein the first cutting seam completely penetrates through the PN junction structure and does not expose the first metal layer;
forming a first protective layer on the surface of the first cutting seam;
forming a second cutting seam in the area where the first cutting seam is located, wherein the second cutting seam penetrates through the first medium layer at most, and the width of the second cutting seam is smaller than that of the first cutting seam;
forming a third cutting seam in the area where the second cutting seam is located by utilizing a laser scribing process, wherein the third cutting seam completely penetrates through the first metal bonding structure and extends into the second substrate;
and cutting a fourth cutting seam from the side of the second substrate, which is far away from the first metal bonding structure, until the fourth cutting seam is communicated with the third cutting seam, so as to form a plurality of independent LED core particles.
2. The method of manufacturing of claim 1, wherein forming an epitaxial structure on the first substrate further comprises: and forming a first limiting layer between the ohmic contact layer and the PN junction structure.
3. The method of manufacturing of claim 1, wherein forming an epitaxial structure on the first substrate further comprises:
a second confinement layer is formed between the current spreading layer and the PN junction structure.
4. The method of manufacturing of claim 2, wherein forming an epitaxial structure on the first substrate further comprises: forming a roughened layer between the ohmic contact layer and the first confinement layer;
before forming the first protective layer on the first kerf surface, the method further comprises: and carrying out roughening treatment on the surface of one side of the roughened layer, which is far away from the first limiting layer, so that the side of the roughened layer, which is far away from the first limiting layer, is a rough surface.
5. The method of claim 1, wherein forming a reflective structure on a side of the epitaxial structure facing away from the first substrate comprises:
forming a first medium layer on the surface of one side, away from the first substrate, of the epitaxial structure, wherein the first medium layer is provided with a plurality of contact holes;
and forming a first metal layer on the surface of one side, away from the epitaxial structure, of the first dielectric layer and in the contact hole, and heating and fusing the first metal layer at a first preset temperature for a first preset time.
6. The method of manufacturing of claim 1, wherein the width of the first cut seam ranges from 20 microns to 50 microns, inclusive; the depth of the first cutting peak ranges from 4 microns to 10 microns, inclusive.
7. The method of claim 1, wherein forming a second dicing line in a region where the first dicing line is located, the second dicing line exposing a portion of the first metal bonding structure region comprises:
and forming a second cutting seam in the area where the first cutting seam is located by utilizing an ICP (inductively coupled plasma) dry etching process or a chemical wet etching process, wherein the second cutting seam takes the fact that the second cutting seam completely penetrates through the current expansion layer as the standard, so that the second cutting seam exposes a part of the area of the first metal bonding structure.
8. The method of claim 7, wherein the width of the second dicing line ranges from 10 microns to 40 microns, inclusive.
9. An LED core particle produced by the production method according to any one of claims 1 to 8, comprising:
a second substrate;
the metal bonding structure is positioned on the surface of the second substrate and comprises a first metal bonding structure;
the reflecting structure is positioned on one side, away from the second substrate, of the metal bonding structure and comprises a first metal layer positioned on the surface of the metal bonding structure and a first dielectric layer positioned on the surface of the first metal layer;
an epitaxial structure on a side of the reflective structure facing away from the metal bond structure, the epitaxial structure comprising: the metal bonding structure comprises a current spreading layer, a PN junction structure and an ohmic contact pattern, wherein the current spreading layer is positioned on one side of the reflecting structure, which is far away from the metal bonding structure;
the bonding pad is positioned on one side, away from the PN junction structure, of the ohmic contact pattern and is electrically connected with the ohmic contact pattern;
wherein, in the direction X of predetermineeing, the width of PN junction structure is less than the width of current spreading layer is less than the width of metal bonding structure, it is on a parallel with to be located PN junction structure both sides and with PN junction structure adjacent two predetermine regional line direction.
10. The LED core particle of claim 9, wherein said epitaxial structure further comprises:
a first confinement layer positioned between the PN junction structure and the ohmic contact pattern; and/or the presence of a gas in the gas,
a second confinement layer located between the PN junction structure and the current spreading layer.
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| CN110660888B (en) * | 2019-11-08 | 2021-02-02 | 扬州乾照光电有限公司 | Light emitting diode and manufacturing method thereof |
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| CN102097553A (en) * | 2010-12-03 | 2011-06-15 | 北京工业大学 | Sapphire substrate-based single chip white light emitting diode |
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| CN101604717A (en) * | 2009-07-15 | 2009-12-16 | 山东华光光电子有限公司 | A kind of vertical GaN-based LED chip and preparation method thereof |
| CN102097553A (en) * | 2010-12-03 | 2011-06-15 | 北京工业大学 | Sapphire substrate-based single chip white light emitting diode |
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