An LED chip and its manufacturing method

Abstract

This invention provides an LED chip and its fabrication method. The method involves providing a composite substrate comprising a first substrate, a bonding layer, and a second substrate stacked sequentially. Next, after growing epitaxial layers and forming corresponding contact electrodes on the surface of the composite substrate, the bonding layer is exposed at the edge of the LED chip by a grinding process along one side of the composite substrate. Finally, the bonding layer and the first substrate are simultaneously removed by etching. This avoids physical grinding of the entire substrate while achieving uniformity in LED chip thinning. Furthermore, in the fabrication process of the LED chip of this invention, the second substrate does not require direct processing, and the final thickness of the LED chip is determined by the thickness of the second substrate. Therefore, the thickness of the LED chip of this invention is easily controlled, making it particularly suitable for small-sized LED chips.

Description

Technical Field

[0001] This invention relates to the field of light-emitting diodes, and more particularly to an LED chip and its manufacturing method. Background Technology

[0002] With the rapid development of LED technology and the gradual improvement of LED luminous efficacy, LED applications are becoming increasingly widespread, and people are paying more and more attention to the development prospects of LEDs in displays. An LED chip's function is to convert electrical energy into light energy. Specifically, it includes an epitaxial stack and N-type and P-type electrodes respectively disposed on the epitaxial stack. The epitaxial stack includes a P-type semiconductor layer, an N-type semiconductor layer, and an active layer located between the N-type and P-type semiconductor layers. When current flows through the LED chip, holes in the P-type semiconductor and electrons in the N-type semiconductor move towards the active layer and recombine there, causing the LED chip to emit light.

[0003] As the size of LED chips used in displays becomes smaller and smaller, the required thickness of the LED chips is also decreasing; taking the current 3*5Mil as an example, the thickness needs to be reduced to below 50μm. This is because: for small-sized LED chips, the heat generated per unit area increases, and the thermal conductivity and thickness of the growth substrate directly affect the heat dissipation of the chip, so the substrate needs to be as thin as possible.

[0004] However, existing polishing equipment suffers from inaccurate end-point detection in its end-point detection module, leading to inaccurate stopping times in the polishing process. This results in some layers that should not be removed being polished and / or some layers that should be removed not being removed, causing uneven polishing thickness. For example, during substrate polishing, the center of the LED chip is often thicker while the edges are polished away. At the same time, due to the stress inherent in the sapphire substrate itself, breakage frequently occurs during the polishing process.

[0005] In view of this, the inventor has specifically designed an LED chip and its manufacturing method, which leads to this invention. Summary of the Invention

[0006] The purpose of this invention is to provide an LED chip and its manufacturing method to solve the problems of uneven grinding thickness and chip breakage that occur in the substrate grinding process of existing LED chips.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for manufacturing an LED chip includes the following steps:

[0009] S01. A composite substrate is provided, the composite substrate comprising a first substrate, a bonding layer and a second substrate stacked sequentially along the growth direction;

[0010] S02. An epitaxial stack is grown on the surface of the composite substrate, the epitaxial stack comprising at least a first type semiconductor layer, an active region and a second type semiconductor layer stacked sequentially along a first direction;

[0011] S03, Etching a local area of ​​the epitaxial stack to a portion of the first type semiconductor layer to form a groove and a mesa;

[0012] S04. Deeply etch the edges of the epitaxial stack to form a substrate exposed portion;

[0013] S05. Deposit an insulating reflective layer, wherein the insulating reflective layer covers the epitaxial stack in such a way that it is held in the exposed portion of the substrate; and etch the insulating reflective layer by photolithography to make it have through holes that expose the bottom surface of the groove and the surface of the mesa portion respectively;

[0014] S06. Fabricate a first electrode and a second electrode, wherein the first electrode is stacked on the bottom surface of the groove through a through-hole and extends upward to the surface of the insulating reflective layer; the second electrode is stacked on the platform through a through-hole and extends upward to the surface of the insulating reflective layer;

[0015] S07. Along one side of the composite substrate, the bonding layer is exposed at the edge of the LED chip by an edge grinding process;

[0016] S08. Simultaneously remove the bonding layer and the first substrate by etching the bonding layer;

[0017] The thickness of the second substrate meets the requirements for supporting the epitaxial stack.

[0018] Preferably, the bonding layer is etched by wet etching in step S08.

[0019] Preferably, the composite substrate is formed by bonding the first substrate and the second substrate together under the action of temperature and pressure.

[0020] Preferably, the bonding layer comprises at least one of silicon oxide and silicon nitride.

[0021] Preferably, the second substrate comprises silicon, sapphire, or silicon carbide.

[0022] Preferably, the first substrate comprises any one of silicon, sapphire, silicon carbide, gallium nitride, and aluminum nitride.

[0023] Preferably, a current spreading layer is formed on the platform.

[0024] Preferably, current-spreading metals are formed on the ITO surface and the bottom surface of the groove, respectively; and the first electrode and the second electrode respectively form contact with the corresponding current-spreading metals by means of through holes embedded in the insulating reflective layer.

[0025] Preferably, the first electrode and the second electrode are composed of one or more of the following materials stacked together: chromium, nickel, aluminum, titanium, platinum, gold, palladium, silver, gold-tin alloy, and tin alloy.

[0026] The present invention also provides an LED chip, which is obtained by any of the manufacturing methods described above.

[0027] As can be seen from the above technical solution, the LED chip and its manufacturing method provided by the present invention involve providing a composite substrate, the composite substrate comprising a first substrate, a bonding layer, and a second substrate stacked sequentially along the growth direction; then, after growing an epitaxial stack and forming corresponding contact electrodes on the surface of the composite substrate, the bonding layer is exposed at the edge of the LED chip by an edge grinding process along one side of the composite substrate; finally, the bonding layer and the first substrate are removed simultaneously by etching the bonding layer; wherein the thickness of the second substrate meets the requirements for supporting the epitaxial stack. Thus, while avoiding physical grinding of the entire substrate, uniformity can be achieved during the thinning of the LED chip. Furthermore, in the manufacturing process of the LED chip of the present invention, there is no need to directly process the second substrate, and the final thickness of the LED chip is determined by the thickness of the second substrate. Therefore, the thickness of the LED chip of the present invention is easy to control, especially suitable for small-sized LED chips. Finally, the LED chip manufacturing method provided by the present invention achieves the above-mentioned beneficial effects while being simple, convenient, and easy to mass-produce. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figures 1 to 8 This is a schematic diagram of the structure corresponding to the steps of the LED chip manufacturing method provided in the embodiments of the present invention;

[0030] Figure 9 This is a schematic diagram of the structure of the LED chip provided in the embodiment of the present invention;

[0031] Explanation of symbols in the diagram:

[0032] 1. Composite substrate; 11. First substrate; 12. Bonding layer; 13. Second substrate;

[0033] 2. Epitaxial stack, 21. Type I semiconductor layer, 22. Active region, 23. Type II semiconductor layer;

[0034] 3. Groove;

[0035] 4. Countertop;

[0036] 5. Exposed substrate portion;

[0037] 6. Current spreading layer;

[0038] 7. Current spreads through metals;

[0039] 8. Insulating reflective layer; 81. Through hole;

[0040] 9. First electrode;

[0041] 10. Second electrode. Detailed Implementation

[0042] To make the content of this invention clearer, the following description, in conjunction with the accompanying drawings, further illustrates the invention. This invention is not limited to this specific embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0043] A method for manufacturing an LED chip includes the following steps:

[0044] S01, such as Figure 1 As shown, a composite substrate 1 is provided, the composite substrate 1 comprising a first substrate 11, a bonding layer 12 and a second substrate 13 stacked sequentially along the growth direction;

[0045] In this embodiment of the invention, the composite substrate 1 is formed by bonding the first substrate 11 and the second substrate 13 together under the action of temperature and pressure.

[0046] In this embodiment of the invention, the bonding layer 12 includes at least one of silicon oxide and silicon nitride.

[0047] In this embodiment of the invention, the second substrate 13 comprises silicon, sapphire, or silicon carbide.

[0048] In this embodiment of the invention, the first substrate 11 includes any one of silicon, sapphire, silicon carbide, gallium nitride, and aluminum nitride.

[0049] S02, such as Figure 2As shown, an epitaxial stack 2 is grown on the surface of the composite substrate 1. The epitaxial stack 2 includes at least a first type semiconductor layer 21, an active region 22 and a second type semiconductor layer 23 stacked sequentially along a first direction.

[0050] In this embodiment of the invention, the types of the first type semiconductor layer 21, the active region 22 and the second type semiconductor layer 23 of the epitaxial stack 2 are not limited in this embodiment. For example, the first type semiconductor layer 21 may be, but is not limited to, a gallium nitride layer, and correspondingly, the second type semiconductor layer 23 may be, but is not limited to, a gallium nitride layer.

[0051] S03, such as Figure 3 As shown, a local area of ​​the epitaxial stack 2 is etched to a portion of the first type semiconductor layer 21 to form a groove 3 and a mesa 4;

[0052] In this embodiment of the invention, a pattern can be formed on the surface of the epitaxial stack 2 by photolithography with photoresist, and then the exposed area of ​​the photoresist can be dry etched by ICP to a portion of the first type semiconductor layer 21 to form a groove 3 and a mesa 4. It should be emphasized that this embodiment does not limit the etching process.

[0053] S04, such as Figure 4 As shown, the edges of the epitaxial stack 2 are deeply etched to form a substrate exposed portion 5;

[0054] In this embodiment of the invention, a pattern can be formed on the surface of the epitaxial stack 2 by photolithography using photoresist, exposing the edges of the epitaxial stack 2. Then, the exposed area can be further dry-etched using ICP to form the substrate exposed portion 5. It should be emphasized that this embodiment does not limit the etching process.

[0055] S05, such as Figure 5 As shown, a current spreading layer 6 is formed on the surface of the platform 4;

[0056] In this embodiment of the invention, the current spreading layer 6 includes one or more of ITO, IZO, IGO, and ZnO.

[0057] In this embodiment of the invention, after depositing the current spreading layer 6 on the entire surface of the LED chip using vapor deposition or sputtering, annealing is performed in a nitrogen protective atmosphere. Then, etching is performed using a mixed solution of HCl (hydrochloric acid) and FeCl3 (ferric chloride) to retain the current spreading layer 6 only on the mesa 4 as the current conductor for the light-emitting mesa 4.

[0058] S06, such as Figure 6 As shown, current-spreading metal 7 is formed on the ITO surface and the bottom surface of the groove 3, respectively;

[0059] In this embodiment of the invention, the current-extending metal 7 includes one or more of chromium, nickel, aluminum, titanium, platinum, gold, palladium, and silver.

[0060] S07, such as Figure 7 As shown, an insulating reflective layer 8 is deposited, which covers the epitaxial stack 2 in such a way that it is held in the exposed portion 5 of the substrate; and the insulating reflective layer 8 is etched by photolithography to make it have through holes 81 that expose the bottom surface of the groove 3 and a portion of the surface of the mesa 4 respectively.

[0061] In this embodiment of the invention, the insulating reflective layer 8 includes a DBR reflective layer.

[0062] In this embodiment of the invention, the exposed substrate 5 surrounds the epitaxial stack 2; the insulating reflective layer 8 is stacked on the second substrate 13 in such a way that it is held in the exposed substrate 5, and surrounds the epitaxial stack 2.

[0063] In this embodiment of the invention, after depositing the DBR reflective layer, a pattern is created on the surface of the LED chip using photoresist, and then the exposed area of ​​the DBR reflective layer is etched using a dry etching method to form a through hole 81 that exposes the bottom surface of the groove 3 and part of the surface of the mesa 4.

[0064] S08, such as Figure 8 As shown, a first electrode 9 and a second electrode 10 are fabricated. The first electrode 9 is stacked on the bottom surface of the groove 3 through a through hole 81 and extends upward to the surface of the insulating reflective layer 8; the second electrode 10 is stacked on the platform 4 through a through hole 81 and extends upward to the surface of the insulating reflective layer 8.

[0065] In this embodiment of the invention, the first electrode 9 and the second electrode 10 are composed of one or more of chromium, nickel, aluminum, titanium, platinum, gold, palladium, silver, gold-tin alloy, and tin alloy stacked together.

[0066] In this embodiment of the invention, an electrode pattern is fabricated on the surface of the DBR reflective layer using negative adhesive, and then metal is deposited using vapor deposition. After removing the gold and adhesive, the electrode pattern fabrication is completed.

[0067] The second electrode 10 is electrically connected to the corresponding current-extending metal 7 through the through hole 81 exposed on the platform 4, and extends upward to the surface of the DBR reflective layer; the first electrode 9 is electrically connected to the corresponding current-extending metal 7 through the through hole 81 exposed on the bottom surface of the groove 3, and extends upward to the surface of the DBR reflective layer.

[0068] S09. Along one side of the composite substrate 1, the bonding layer 12 is exposed at the edge of the LED chip by a grinding process.

[0069] S10. By etching the bonding layer 12, the bonding layer 12 and the first substrate 11 are removed simultaneously.

[0070] The thickness of the second substrate 13 meets the requirements for supporting the epitaxial stack 2.

[0071] The present invention also provides an LED chip, which is obtained by any of the manufacturing methods described above.

[0072] As can be seen from the above technical solution, the LED chip and its manufacturing method provided by the present invention involve providing a composite substrate 1, which includes a first substrate 11, a bonding layer 12, and a second substrate 13 stacked sequentially along the growth direction. Next, after growing an epitaxial stack 2 on the surface of the composite substrate 1 and forming corresponding contact electrodes, the bonding layer 12 is exposed at the edge of the LED chip by a grinding process along one side of the composite substrate 1. Finally, the bonding layer 12 and the first substrate 11 are simultaneously removed by etching. The thickness of the second substrate 13 meets the requirements for supporting the epitaxial stack 2. Thus, while avoiding physical grinding of the entire substrate, uniformity can be achieved during the thinning of the LED chip. Furthermore, in the manufacturing process of the LED chip of the present invention, there is no need to directly process the second substrate 13, and the final thickness of the LED chip is determined by the thickness of the second substrate 13. Therefore, the thickness of the LED chip of the present invention is easy to control, especially suitable for small-sized LED chips. Finally, the LED chip manufacturing method provided by the present invention achieves the above-mentioned beneficial effects while being simple, convenient, and easy to mass-produce.

[0073] The apparatus provided in this embodiment of the invention operates on the same principle and produces the same technical effects as the aforementioned method embodiments. For the sake of brevity, any parts not mentioned in the apparatus embodiments can be referred to the corresponding content in the aforementioned method embodiments. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, apparatuses, and units described above can all be referred to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0075] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not 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

1. A method of fabricating an LED chip, the method comprising: Includes the following steps: ​ S01. A composite substrate is provided, the composite substrate comprising a first substrate, a bonding layer and a second substrate stacked sequentially along the growth direction; S02. An epitaxial stack is grown on the surface of the composite substrate, the epitaxial stack comprising at least a first type semiconductor layer, an active region and a second type semiconductor layer stacked sequentially along a first direction; S03, Etching a local area of ​​the epitaxial stack to a portion of the first type semiconductor layer to form a groove and a mesa; S04. Deeply etch the edges of the epitaxial stack to form a substrate exposed portion; S05. Deposit an insulating reflective layer, wherein the insulating reflective layer covers the epitaxial stack in such a way that it is held in the exposed portion of the substrate; and etch the insulating reflective layer by photolithography to make it have through holes that expose the bottom surface of the groove and the surface of the mesa portion respectively; S06. Fabricate a first electrode and a second electrode, wherein the first electrode is stacked on the bottom surface of the groove through a through-hole and extends upward to the surface of the insulating reflective layer; the second electrode is stacked on the platform through a through-hole and extends upward to the surface of the insulating reflective layer; S07. Along one side of the composite substrate, the bonding layer is exposed at the edge of the LED chip by an edge grinding process; S08. Simultaneously remove the bonding layer and the first substrate by etching the bonding layer; The thickness of the second substrate meets the requirements for supporting the epitaxial stack.

2. The method of claim 1, wherein In step S08, the bonding layer is etched by wet etching.

3. The method of claim 1, wherein the LED chip is formed on a substrate. The composite substrate is formed by bonding the first substrate and the second substrate together under the action of temperature and pressure.

4. The method of claim 1, wherein the LED chip is formed on a sapphire substrate. The bonding layer includes at least one of silicon oxide and silicon nitride.

5. The method for manufacturing an LED chip according to claim 1, characterized in that, The second substrate comprises silicon, sapphire, or silicon carbide.

6. The method for manufacturing an LED chip according to claim 1, characterized in that, The first substrate includes any one of silicon, sapphire, silicon carbide, gallium nitride, and aluminum nitride.

7. The method for manufacturing an LED chip according to claim 1, characterized in that, It also includes forming a current spreading layer on the platform.

8. The method for manufacturing an LED chip according to claim 7, characterized in that, Current-spreading metal is formed on the surface of the current-spreading layer and the bottom surface of the groove, respectively; and the first electrode and the second electrode respectively form contact with the corresponding current-spreading metal by means of through holes embedded in the insulating reflective layer.

9. The method for manufacturing an LED chip according to claim 1, characterized in that, The first electrode and the second electrode are composed of one or more of the following materials stacked together: chromium, nickel, aluminum, titanium, platinum, gold, palladium, silver, gold-tin alloy, and tin alloy.

10. An LED chip, characterized in that, The LED chip is obtained by the manufacturing method according to any one of claims 1-9.

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