A flip-chip LED chip and its preparation method

Abstract

The present application provides a flip-chip LED chip and a preparation method thereof, the preparation method comprising: forming a patterned peeling layer on a patterned epitaxial layer; forming a patterned interface improvement layer on the patterned peeling layer, wherein the patterned interface improvement layer comprises a plurality of interface improvement blocks, and the cross-sectional width of the interface improvement blocks gradually increases in the direction in which the interface improvement layer is away from the peeling layer; forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, wherein the reflective layer on the patterned interface improvement layer is spaced from the reflective layer on the patterned epitaxial layer, and the reflective layer is a Bragg reflector; and etching the patterned peeling layer so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer. The preparation method of the flip-chip LED chip provided by the present application is low in cost, the reflective effect of the reflective layer is good, and the luminous performance and stability of the flip-chip LED chip are good.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a flip-chip LED chip and a preparation method thereof. Background Art

[0002] Light Emitting Diode (LED) is an electroluminescent semiconductor light-emitting device. It has been widely used in lighting, display, medical treatment, optical communication and other fields due to its advantages of low energy consumption, small size, long life, good stability, fast response and stable wavelength. According to different architectures, LED chips can be divided into normal LED chips, flip-chip LED chips and vertical LED chips. Among them, flip-chip LED chips have the advantages of low voltage, high brightness, high reliability and high saturation current density, and have excellent development prospects.

[0003] In the related art, a flip-chip LED chip generally includes a reflective layer, which is arranged on the same side as the electrode in the flip-chip LED chip to reflect the light emitted by the epitaxial layer of the flip-chip LED chip and emit it to the outside of the flip-chip LED chip. The reflective layer can be a metal reflective layer or a Bragg reflector (full name: Distributed Bragg Reflector, abbreviated as: DBR), where DBR is a periodic structure composed of two material layers with different refractive indices arranged alternately, and has the advantages of high reflectivity, large reflection coverage, and electrical insulation, and has gradually become the mainstream choice for the reflective layer in flip-chip LED chips.

[0004] The applicant further discovered that in practical applications, DBR is usually a graphical structure, which means that in order to meet the application requirements of DBR in flip-chip LED chips, DBR needs to be graphically processed. However, currently, inductively coupled plasma (ICP) etching is usually used to prepare graphical DBRs, and the disadvantages of ICP etching include but are not limited to: DBR etching is difficult and time-consuming, which increases the preparation cost; the depth cannot be accurately controlled, and it is easy to etch the film layer below the DBR, resulting in over-etching problems, affecting the luminous performance of the flip-chip LED chip; the interface formed by etching will expose the internal structure of the DBR, thereby affecting the reflection effect of the reflective layer and the stability of the flip-chip LED chip.

[0005] Therefore, how to reduce the preparation cost while eliminating the over-etching problem and improving the interface structure of the reflective layer, thereby improving the reflective effect of the reflective layer and improving the luminous performance and stability of the flip-chip LED chip, is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] The present application provides a flip-chip LED chip and a preparation method thereof, which can effectively solve the problems of high preparation cost, poor reflection effect of the reflection layer, and poor luminous performance and stability of the flip-chip LED chip in the related art.

[0007] In a first aspect, the present application provides a method for preparing a flip-chip LED chip, the method for preparing a flip-chip LED chip comprising:

[0008] forming a patterned lift-off layer on the patterned epitaxial layer;

[0009] forming a patterned interface improvement layer on the patterned peeling layer, wherein the patterned interface improvement layer comprises a plurality of interface improvement blocks, and the cross-sectional width of the interface improvement blocks gradually increases in a direction in which the interface improvement layer is away from the peeling layer;

[0010] forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, wherein the reflective layer on the patterned interface improvement layer is spaced apart from the reflective layer on the patterned epitaxial layer, and the reflective layer is a Bragg reflector;

[0011] The patterned peeling layer is subjected to an etching treatment so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer.

[0012] Optionally, the step of forming a patterned interface improvement layer on the patterned release layer includes:

[0013] forming a positive photoresist layer on the patterned epitaxial layer and the patterned lift-off layer;

[0014] Partially exposing the positive photoresist layer by using an exposure device disposed on a side of the positive photoresist layer away from the patterned stripping layer;

[0015] Cleaning the positive photoresist layer to form a patterned positive photoresist layer, wherein the positive photoresist layer has a plurality of through holes, and the cross-sectional widths of the through holes increase in sequence in a direction from the interface improvement layer away from the stripping layer;

[0016] Using the patterned positive photoresist layer as a mask, an interface improvement material is deposited to form a patterned interface improvement layer on the patterned stripping layer.

[0017] Optionally, in the step of forming a patterned lift-off layer on the patterned epitaxial layer, the lift-off layer is an aluminum oxide layer;

[0018] In the step of forming a patterned interface improvement layer on the patterned release layer, the patterned interface improvement layer is an aluminum metal layer;

[0019] The step of etching the patterned stripping layer so that the patterned interface improvement layer together with the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer includes etching the patterned stripping layer using ammonia water with a concentration of 10% to 30%.

[0020] Optionally, in the step of forming a patterned lift-off layer on the patterned epitaxial layer, the patterned lift-off layer has a first thickness;

[0021] In the step of forming a patterned interface improvement layer on the patterned release layer, the patterned interface improvement layer has a second thickness;

[0022] Wherein, the second thickness is greater than the first thickness.

[0023] Optionally, in the step of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, the reflective layer on the patterned epitaxial layer has a plurality of openings, and the patterned stripping layer is arranged in the plurality of openings, wherein in the direction where the interface improvement layer moves away from the stripping layer, the cross-sectional width of the opening gradually increases.

[0024] Optionally, in the step of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, the reflective layer on the patterned epitaxial layer includes a first sub-reflective layer to an nth sub-reflective layer stacked sequentially on the patterned epitaxial layer, where n is greater than or equal to 2, wherein each of the first sub-reflective layer to the nth sub-reflective layer has an inclined interface on a side facing the opening, and the lengths of the inclined interface from the first sub-reflective layer to the nth sub-reflective layer increase sequentially.

[0025] Optionally, in the step of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, a sidewall of the opening is an inclined interface of the nth sub-reflective layer.

[0026] Optionally, before the step of forming a patterned lift-off layer on the patterned epitaxial layer, the method further comprises:

[0027] Forming an epitaxial layer on a substrate, wherein the epitaxial layer includes a first semiconductor layer, a light emitting layer, and a second semiconductor layer sequentially stacked on the substrate;

[0028] forming a transparent conductive layer on the epitaxial layer;

[0029] Performing patterning on the transparent conductive layer to form a patterned transparent conductive layer;

[0030] The second semiconductor layer and the light emitting layer in the epitaxial layer are patterned to form a patterned epitaxial layer.

[0031] Optionally, after the step of etching the patterned peeling layer so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer, the method further includes:

[0032] A patterned electrode layer is formed on the patterned epitaxial layer, wherein the patterned electrode layer includes a plurality of electrodes, and each of the electrodes is surrounded by a reflective layer on the patterned epitaxial layer.

[0033] In a second aspect, the present application provides a flip-chip LED chip, which includes a patterned epitaxial layer and a reflective layer arranged on the patterned epitaxial layer, the reflective layer on the patterned epitaxial layer having a plurality of openings, electrodes being arranged in the openings, wherein the cross-sectional width of the openings gradually increases in a direction in which the reflective layer moves away from the patterned epitaxial layer; the reflective layer on the patterned epitaxial layer includes a first sub-reflective layer to an nth sub-reflective layer stacked sequentially on the patterned epitaxial layer, n being greater than or equal to 2, wherein each of the first sub-reflective layer to the nth sub-reflective layer has an inclined interface on a side facing the opening, and the lengths of the inclined interface of the first sub-reflective layer to the inclined interface of the nth sub-reflective layer increase sequentially; and the sidewall of the opening is the inclined interface of the nth sub-reflective layer.

[0034] The present application provides a flip-chip LED chip and a preparation method thereof, the preparation method of the flip-chip LED chip comprising: forming a patterned peeling layer on a patterned epitaxial layer; forming a patterned interface improvement layer on the patterned peeling layer, wherein the patterned interface improvement layer comprises a plurality of interface improvement blocks, and the cross-sectional width of the interface improvement blocks gradually increases in the direction in which the interface improvement layer is away from the peeling layer; forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, wherein the reflective layer on the patterned interface improvement layer is spaced apart from the reflective layer on the patterned epitaxial layer, and the reflective layer is a Bragg reflector; and etching the patterned peeling layer so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer. The preparation method of the flip-chip LED chip provided by the present application is low in cost, the reflective effect of the reflective layer is good, and the luminous performance and stability of the flip-chip LED chip are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0036] Figure 1 It is a schematic diagram of the structure of a DBR formed by ICP etching in the related art.

[0037] Figure 2 A schematic flow chart of a method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0038] Figure 3 This is a structural schematic diagram corresponding to step S10 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0039] Figure 4 This is a structural schematic diagram corresponding to step S20 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0040] Figure 5 This is a structural schematic diagram corresponding to step S30 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0041] Figure 6 This is a structural schematic diagram corresponding to step S40 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0042] Figure 7 This is a schematic flow chart corresponding to step S20 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0043] Figure 8 A schematic diagram of the structure of the reflective layer provided in an embodiment of the present application.

[0044] Fig. 9 This is a structural schematic diagram corresponding to step S01 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0045] Fig.10 This is a structural schematic diagram corresponding to step S02 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0046] Fig.11 This is a structural schematic diagram corresponding to step S03 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0047] Fig.12 This is a structural schematic diagram corresponding to step S04 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0048] Fig.13This is a structural schematic diagram corresponding to step S50 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application.

[0049] Fig.14 This is a schematic diagram of the structure of the flip-chip LED chip provided in an embodiment of the present application.

[0050] Description of reference numerals:

[0051] Edge interface A1 formed by etching; sub-membrane layer M1; substrate 11; epitaxial layer 12; first semiconductor layer 121; light-emitting layer 122; second semiconductor layer 123; transparent conductive layer 13; peeling layer 14; interface improvement layer 15; interface improvement block 151; reflective layer 16; opening 160; first sub-reflective layer 161; nth sub-reflective layer 16n; inclined interface AB; electrode layer 17; electrode 171. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0053] The terms "first" and "second" in this document are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0054] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0056] In the related art, the preparation method of flip-chip LED chips usually adopts ICP etching to prepare patterned DBR, and the disadvantages of ICP etching include but are not limited to: the etching of DBR film layer is difficult and time-consuming, which increases the preparation cost; the depth cannot be accurately controlled, and it is easy to etch the film layer below the DBR, resulting in over-etching problems, affecting the luminous performance of the flip-chip LED chip; the interface formed by etching will expose the internal structure of the DBR, thereby affecting the reflective effect of the reflective layer and the stability of the flip-chip LED chip. Specifically, Figure 1 is a schematic diagram of the structure of a DBR formed by ICP etching in the related art, referring to Figure 1 The edge interface A1 formed by etching of the DBR is composed of the side walls of multiple sub-film layers M1 in the DBR, which exposes the internal structure of the DBR, thereby affecting the reflection effect of the reflection layer and the stability of the flip-chip LED chip.

[0057] In order to improve the problems of high preparation cost, poor reflection effect of the reflection layer, and poor luminous performance and stability of the flip-chip LED chip in the preparation method of the related art, the present application provides a flip-chip LED chip preparation method and a flip-chip LED chip.

[0058] In a first aspect, an embodiment of the present application provides a method for preparing a flip-chip LED chip. Figure 2 This is a schematic diagram of the process for preparing a flip-chip LED chip provided in an embodiment of the present application. Figure 2 As shown, the method for preparing a flip-chip LED chip provided in the embodiment of the present application includes step S10, step S20, step S30, and step S40.

[0059] Figure 3 This is a schematic diagram of the structure corresponding to step S10 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Figure 2 and Figure 3 As shown, step S10 includes: forming a patterned lift-off layer 14 on the patterned epitaxial layer 12 .

[0060] Figure 4 This is a schematic diagram of the structure corresponding to step S20 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Figure 2and Figure 4 As shown, step S20 includes: forming a patterned interface improvement layer 15 on the patterned peeling layer 14, wherein the patterned interface improvement layer 15 includes a plurality of interface improvement blocks 151, and in the direction in which the interface improvement layer 15 is away from the peeling layer 14, the cross-sectional width of the interface improvement block 151 gradually increases.

[0061] Figure 5 This is a schematic diagram of the structure corresponding to step S30 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Figure 2 and Figure 5 As shown, step S30 includes: forming a reflective layer 16 on the patterned epitaxial layer 12 and the patterned interface improvement layer 15, wherein the reflective layer 16 on the patterned interface improvement layer 15 is spaced apart from the reflective layer 16 on the patterned epitaxial layer 12, and the reflective layer 16 is a Bragg reflector.

[0062] Figure 6 This is a schematic diagram of the structure corresponding to step S40 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Figure 2 and Figure 6 As shown, step S04 includes: etching the patterned peeling layer 14 so that the patterned interface improvement layer 15 together with the reflective layer 16 on the patterned interface improvement layer 15 are peeled off from the patterned epitaxial layer 12 .

[0063] In the method for preparing a flip-chip LED chip provided in an embodiment of the present application, step S10 forms a patterned peeling layer 14 on the patterned epitaxial layer 12, and then, the patterned peeling layer 14 can be used to form an easy-to-peel-off area and a difficult-to-peel-off area on the patterned epitaxial layer 12, so that, in the subsequent step S30, after forming a reflective layer 16 specifically as a Bragg reflector on the patterned epitaxial layer 12, the patterned peeling layer 14 can be corroded by performing step S40 without using an etching process to achieve removal of the reflective layer 16 in a local area, thereby achieving the preparation of a patterned Bragg reflector while improving the problem of high preparation cost caused by the difficulty and time of etching the Bragg reflector, and improving the problem of decreased luminous performance of the flip-chip LED chip caused by over-etching due to the inability to accurately control the depth of the DBR.

[0064] Secondly, in the method for preparing a flip-chip LED chip provided in an embodiment of the present application, a patterned interface improvement layer 15 is formed on the patterned peeling layer 14 in step S20, and then, the composite structure of the stacked peeling layer 14 and the interface improvement layer 15 can be used to form a larger height difference between the easy-to-peel area and the difficult-to-peel area, so that in the subsequent step S30, the reflective layer 16 on the patterned interface improvement layer 15 is spaced from the reflective layer 16 on the patterned epitaxial layer 12, and then, in step S40, when the patterned interface improvement layer 15 together with the reflective layer 16 on the patterned interface improvement layer 15 are peeled off from the patterned epitaxial layer 12, the peeling yield is improved, and the film integrity of the edge interface of the reflective layer 16 on the patterned epitaxial layer 12 is maintained, thereby reducing the preparation cost and improving the reflective effect of the reflective layer 16 and the stability of the flip-chip LED chip.

[0065] Again, in the method for preparing a flip-chip LED chip provided in an embodiment of the present application, in step S20, the cross-sectional width of the interface improvement block 151 is gradually increased in the direction of the interface improvement layer 15 away from the peeling layer 14, thereby facilitating in step S30 the improvement of the edge interface morphology of the reflective layer 16 on the patterned epitaxial layer 12, thereby preventing the internal structure of the Bragg reflector from being exposed at the edge interface, thereby improving the reflection effect of the reflective layer 16 on the patterned epitaxial layer 12 at the edge interface and enhancing the stability of the flip-chip LED chip.

[0066] In some implementations of the present application, step S10, step S20, step S30, and step S40 are performed sequentially, that is, step S20 is performed after step S10 is completed, step S30 is performed after step S20 is performed, and step S40 is performed after step S30 is performed.

[0067] Figure 7 This is a flow chart corresponding to step S20 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Figure 7 As shown, in some embodiments of the present application, step S20 includes step S21, step S22, step S23, and step S24, wherein step S21, step S22, step S23, and step S24 are performed sequentially.

[0068] In some embodiments of the present application, step S21 includes: forming a positive photoresist layer (not shown in the figure) on the patterned epitaxial layer 12 and the patterned lift-off layer 14 .

[0069] In some embodiments of the present application, step S22 includes: locally exposing the positive photoresist layer by using an exposure device disposed on a side of the positive photoresist layer away from the patterned lift-off layer 14 .

[0070] In some embodiments of the present application, step S23 includes: cleaning the positive photoresist layer to form a patterned positive photoresist layer, wherein the positive photoresist layer has a plurality of through holes (not shown in the figure), and the cross-sectional width of the through holes increases successively in the direction from the interface improvement layer 15 away from the stripping layer 14.

[0071] In some embodiments of the present application, step S24 includes: using the patterned positive photoresist layer as a mask, depositing an interface improvement material to form a patterned interface improvement layer 15 on the patterned lift-off layer 14 .

[0072] In the preparation method of the flip-chip LED chip provided in the embodiment of the present application, the present application adopts the method of first forming a positive photoresist layer covering the patterned epitaxial layer 12 and the patterned stripping layer 14, and then using an exposure device arranged on the side of the positive photoresist layer away from the interface improvement layer 15 to locally expose the positive photoresist layer, thereby being able to utilize the characteristics that the exposed part of the positive photoresist will be removed by the developer and the exposure intensity will gradually weaken with the exposure depth. After the positive photoresist layer is cleaned, an inverted trapezoidal through hole is formed in the patterned positive photoresist layer; further, subsequently, an interface improvement block 151 with an inverted trapezoidal structure and arranged corresponding to the patterned stripping layer 14 can be formed in each of the through holes by depositing an interface improvement material.

[0073] Continue to refer to Figure 7 In some embodiments of the present application, step S20 also includes step S25, and step S25 is located after step S24. Step S25 includes: removing the patterned positive photoresist layer.

[0074] In some embodiments of the present application, in the step S10 of forming a patterned stripping layer 14 on the patterned epitaxial layer 12, the stripping layer 14 is an aluminum oxide layer; in the step S20 of forming a patterned interface improvement layer 15 on the patterned stripping layer 14, the patterned interface improvement layer 15 is an aluminum metal layer; the step S40 of corroding the patterned stripping layer 14 so that the patterned interface improvement layer 15 together with the reflective layer 16 on the patterned interface improvement layer 15 are stripped from the patterned epitaxial layer 12 includes corroding the patterned stripping layer 14 using ammonia water with a concentration of 10% to 30%.

[0075] In the method for preparing the flip-chip LED chip provided in the embodiment of the present application, since the peeling layer 14 is an aluminum oxide layer, and the interface improvement layer 15 is an aluminum metal layer, the aluminum oxide layer and the aluminum metal layer have strong temperature resistance (can maintain stable performance at an operating temperature above 200 degrees Celsius), and the cost is relatively low. Therefore, when executing step S30, a high-temperature process can be used to deposit a Bragg reflector with a multilayer film structure, which is conducive to forming a reflective layer 16 with a denser film structure and better reflection effect, thereby improving the luminous performance and stability of the flip-chip LED chip. On this basis, the present application uses ammonia water with a concentration of 10% to 30% to corrode the patterned peeling layer 14, so that it can take into account the peeling effect and efficiency without affecting other film layers (such as the epitaxial layer 12 and the reflective layer 16).

[0076] In some embodiments of the present application, in the step S30 of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, a reflective layer 16 is formed on the patterned epitaxial layer 12 and the patterned interface improvement layer 15 at 200 to 400 degrees Celsius.

[0077] It should be noted that, in the related art, although the photoresist layer can also be used as a stripping layer, the temperature resistance of the photoresist layer is poor, which will affect the temperature parameters in the film forming process of the reflective layer 16, thereby causing the problem of reduced film density of each film layer in the Bragg reflector. However, in the method for preparing the flip-chip LED chip provided by the present application, when executing step S30, the stripping layer 14 and the interface improvement layer 15 can both be applied to high temperatures above 200 degrees Celsius, which is conducive to forming a reflective layer 16 with a denser film structure and better reflection effect.

[0078] In some embodiments of the present application, in the step S10 of forming a patterned peeling layer 14 on the patterned epitaxial layer 12, the patterned peeling layer 14 has a first thickness; in the step S20 of forming a patterned interface improvement layer 15 on the patterned peeling layer 14, the patterned interface improvement layer 15 has a second thickness; wherein the second thickness is greater than the first thickness.

[0079] In the method for preparing a flip-chip LED chip provided in an embodiment of the present application, the applicant has discovered in research that the process of etching the patterned peeling layer 14 in step S40 will be affected by the process of forming the reflective layer 16 on the patterned epitaxial layer 12 and the patterned interface improvement layer 15 in step S30. The reason is that when the height difference between the easy-to-peel region where the patterned peeling layer 14 is provided and the non-easy-to-peel region where the patterned peeling layer 14 is not provided is small, the reflective layer 16 formed on the patterned epitaxial layer 12 and the reflective layer 16 formed on the patterned interface improvement layer 15 are often provided continuously, which will result in the solution that can corrode the peeling layer 14 being unable to smoothly contact the peeling layer 14, thereby reducing the preparation yield. In order to improve this problem, the present application limits the thickness threshold of the interface improvement layer 15. By making the thickness of the interface improvement layer 15 greater than the thickness of the stripping layer 14, the reflective layer 16 on the patterned interface improvement layer 15 can be spaced apart from the reflective layer 16 on the patterned epitaxial layer 12 in step S30, thereby improving the stripping yield of the stripping layer 14 and reducing the preparation cost.

[0080] In some embodiments of the present application, the thickness of the interface improvement layer 15 is 2 to 100 times the thickness of the release layer 14 .

[0081] Continue to refer to Figure 5 In some embodiments of the present application, in the step S30 of forming the reflective layer 16 on the patterned epitaxial layer 12 and the patterned interface improvement layer 15, the reflective layer 16 on the patterned epitaxial layer 12 has a plurality of openings 160, and the patterned peeling layer 14 is arranged in the plurality of openings 160, wherein in the direction in which the interface improvement layer 15 is away from the peeling layer 14, the cross-sectional width of the opening 160 gradually increases.

[0082] In the method for preparing a flip-chip LED chip provided in an embodiment of the present application, the present application can form an inverted trapezoidal opening 160 in the reflective layer 16 on the patterned epitaxial layer 12 under the influence of the inverted trapezoidal interface improvement block 151. When the opening 160 in the reflective layer 16 on the patterned epitaxial layer 12 is an inverted trapezoid, it is more conducive to improving the integrity of the edge interface of the reflective layer 16, and further conducive to improving the reflection efficiency of the reflective layer 16, thereby improving the luminous effect and stability of the flip-chip LED chip.

[0083] Figure 8 This is a schematic diagram of the structure of the reflective layer provided in the embodiment of the present application. Figure 8As shown, in some embodiments of the present application, in the step S30 of forming the reflective layer 16 on the patterned epitaxial layer 12 and the patterned interface improvement layer 15, the reflective layer 16 on the patterned epitaxial layer 12 includes a first sub-reflective layer 161 to an nth sub-reflective layer 16n sequentially stacked on the patterned epitaxial layer 12, where n is greater than or equal to 2, wherein each of the first sub-reflective layer 161 to the nth sub-reflective layer 16n has an inclined interface AB on the side facing the opening 160, and the lengths of the inclined interface AB from the first sub-reflective layer 161 to the nth sub-reflective layer 16n increase sequentially.

[0084] In the method for preparing a flip-chip LED chip provided in the embodiment of the present application, since each sub-reflection layer from the first sub-reflection layer 161 to the nth sub-reflection layer 16n has an inclined interface AB on the side facing the opening 160, and the lengths of the inclined interface AB in the first sub-reflection layer 161 to the inclined interface AB in the nth sub-reflection layer 16n increase successively, it is possible to enhance the reflection effect of each inclined interface AB, thereby improving the reflection efficiency of the reflection layer 16, and making the reflection efficiency of each sub-reflection layer 16 in the reflection layer 16 consistent in each region, thereby improving the luminous effect of the flip-chip LED chip.

[0085] In some embodiments of the present application, the refractive indices of two adjacent sub-reflection layers 16 are different.

[0086] In some embodiments of the present application, in the step S30 of forming the reflective layer 16 on the patterned epitaxial layer 12 and the patterned interface improvement layer 15 , the sidewall of the opening 160 is the inclined interface AB of the nth sub-reflective layer 16 n .

[0087] In the method for preparing a flip-chip LED chip provided in the embodiment of the present application, since the side wall of the opening 160 in step S30 is the inclined interface AB of the nth sub-reflection layer 16n, the outermost sub-reflection layer 16 can be used to cover the remaining sub-reflection layers 16, so that the structure of the reflective layer 16 at the edge interface can be more complete, which is beneficial to the improvement of reflection efficiency and stability, and further improves the luminous effect and stability of the flip-chip LED chip.

[0088] In some embodiments of the present application, before the step of forming a patterned peeling layer 14 on the patterned epitaxial layer 12, the method for preparing the flip-chip LED chip also includes step S01, step S02, step S03 and step S04, wherein step S01, step S02, step S03 and step S04 are performed sequentially.

[0089] Fig. 9This is a schematic diagram of the structure corresponding to step S01 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Fig. 9 As shown, step S01 includes: forming an epitaxial layer 12 on a substrate 11 , wherein the epitaxial layer 12 includes a first semiconductor layer 121 , a light emitting layer 122 , and a second semiconductor layer 123 sequentially stacked on the substrate 11 .

[0090] In some embodiments of the present application, the substrate 11 may be a sapphire substrate 11; the first semiconductor layer 121 may be an N-type semiconductor layer, the light-emitting layer 122 may be a multi-quantum well layer, and the second semiconductor layer 123 may be a P-type semiconductor layer.

[0091] Fig.10 This is a schematic diagram of the structure corresponding to step S02 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Fig.10 As shown, step S02 includes: forming a transparent conductive layer 13 on the epitaxial layer 12 .

[0092] In some embodiments of the present application, the transparent conductive layer 13 may be an indium tin oxide (English full name: IndiumTinOxide; abbreviated: ITO) layer.

[0093] Fig.11 This is a schematic diagram of the structure corresponding to step S03 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Fig.11 As shown, step S03 includes: performing patterning on the transparent conductive layer 13 to form a patterned transparent conductive layer 13 .

[0094] In some embodiments of the present application, the patterned transparent conductive layer 13 is used to subsequently electrically connect the P-type electrode and the second semiconductor layer 123 to achieve a current expansion function, thereby improving the overall performance of the flip-chip LED chip and extending its service life.

[0095] Fig.12 This is a schematic diagram of the structure corresponding to step S04 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Fig.12 As shown, step S04 includes: performing patterning on the second semiconductor layer 123 and the light emitting layer 122 in the epitaxial layer 12 to form a patterned epitaxial layer 12 .

[0096] In some embodiments of the present application, in the patterned epitaxial layer 12, the second semiconductor layer 123 and the light-emitting layer 122 in a local area are removed, and correspondingly, the first semiconductor layer 121 in a local area is exposed, and the exposed first semiconductor layer 121 can subsequently be electrically connected to the N-type electrode.

[0097] Fig.13 This is a schematic diagram of the structure corresponding to step S50 in the method for preparing a flip-chip LED chip provided in an embodiment of the present application. Fig.13 In some embodiments of the present application, after the step S40 of corroding the patterned peeling layer 14 so that the patterned interface improvement layer 15 together with the reflective layer 16 on the patterned interface improvement layer 15 are peeled off from the patterned epitaxial layer 12, the method for preparing the flip-chip LED chip also includes a step S50, wherein step S50 includes: forming a patterned electrode layer 17 on the patterned epitaxial layer 12, wherein the patterned electrode layer 17 includes a plurality of electrodes 171, and each of the electrodes 171 is surrounded by the reflective layer 16 on the patterned epitaxial layer 12.

[0098] In some embodiments of the present application, the plurality of electrodes 171 include a P-type electrode and an N-type electrode, wherein the P-type electrode is electrically connected to the second semiconductor layer 123 through the transparent conductive layer 13 , and the N-type electrode is electrically connected to the first semiconductor layer 121 .

[0099] In some embodiments of the present application, the electrode 171 is connected to the reflective layer 16 on the patterned epitaxial layer 12 to avoid light leakage from the electrode layer 17 .

[0100] In a second aspect, an embodiment of the present application provides a flip-chip LED chip. Fig.14 This is a schematic diagram of the structure of the flip-chip LED chip provided in the embodiment of the present application. Figure 8 and Fig.14 As shown, the flip-chip LED chip includes a patterned epitaxial layer 12 and a reflective layer 16 arranged on the patterned epitaxial layer 12, the reflective layer 16 on the patterned epitaxial layer 12 has a plurality of openings 160, and electrodes 171 are arranged in the openings 160, wherein the cross-sectional width of the openings 160 gradually increases in the direction in which the reflective layer 16 is away from the patterned epitaxial layer 12; the reflective layer 16 on the patterned epitaxial layer 12 includes a first sub-reflective layer 161 to an nth sub-reflective layer 16n sequentially stacked on the patterned epitaxial layer 12, where n is greater than or equal to 2, wherein each of the first sub-reflective layer 161 to the nth sub-reflective layer 16n has an inclined interface AB on the side facing the opening 160, and the lengths of the inclined interface AB of the first sub-reflective layer 161 to the inclined interface AB of the nth sub-reflective layer 16n increase sequentially; the sidewall of the opening 160 is the inclined interface AB of the nth sub-reflective layer 16n.

[0101] In the flip-chip LED chip provided in the embodiment of the present application, since the opening 160 in the reflective layer 16 on the patterned epitaxial layer 12 is an inverted trapezoid, it is more conducive to improving the integrity of the edge interface of the reflective layer 16, and further conducive to improving the reflection efficiency of the reflective layer 16, thereby improving the luminous effect and stability of the flip-chip LED chip.

[0102] In addition, in the flip-chip LED chip provided in the embodiment of the present application, since each sub-reflection layer in the first sub-reflection layer 161 to the nth sub-reflection layer 16n has an inclined interface AB on the side facing the opening 160, and the lengths of the inclined interface AB in the first sub-reflection layer 161 to the inclined interface AB in the nth sub-reflection layer 16n increase successively, it is possible to enhance the reflection effect of each inclined interface AB, thereby improving the reflection efficiency of the reflection layer 16, and making the reflection efficiency of each sub-reflection layer 16 in the reflection layer 16 consistent in each region, thereby improving the luminous effect of the flip-chip LED chip.

[0103] In addition, in the flip-chip LED chip provided in the embodiment of the present application, since the side wall of the opening 160 is the inclined interface AB of the nth sub-reflection layer 16n, the outermost sub-reflection layer 16 can be used to cover the remaining sub-reflection layers 16, so that the structure of the reflective layer 16 at the edge interface can be more complete, which is beneficial to the improvement of reflection efficiency and stability, and further improves the luminous effect and stability of the flip-chip LED chip.

[0104] In some embodiments of the present application, the flip-chip LED chip is prepared by any of the above-mentioned methods for preparing a flip-chip LED chip.

[0105] In some embodiments of the present application, the patterned epitaxial layer 12 includes a first semiconductor layer 121 , a light emitting layer 122 , and a second semiconductor layer 123 which are stacked in sequence.

[0106] In some embodiments of the present application, the flip-chip LED chip includes a transparent conductive layer 13 disposed on the patterned epitaxial layer 12 .

[0107] In some embodiments of the present application, the flip-chip LED chip includes a substrate 11. Of course, in other embodiments of the present application, the substrate 11 may be omitted.

[0108] In some embodiments of the present application, a buffer layer or other functional layer may be provided between the substrate 11 and the patterned epitaxial layer 12 .

[0109] In summary, the present application provides a flip-chip LED chip and a preparation method thereof, the preparation method of the flip-chip LED chip comprising: forming a patterned peeling layer on a patterned epitaxial layer; forming a patterned interface improvement layer on the patterned peeling layer, wherein the patterned interface improvement layer comprises a plurality of interface improvement blocks, and the cross-sectional width of the interface improvement blocks gradually increases in the direction in which the interface improvement layer is away from the peeling layer; forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, wherein the reflective layer on the patterned interface improvement layer is spaced apart from the reflective layer on the patterned epitaxial layer, and the reflective layer is a Bragg reflector; and etching the patterned peeling layer so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer. The preparation method of the flip-chip LED chip provided by the present application is low in cost, the reflective effect of the reflective layer is good, and the luminous performance and stability of the flip-chip LED chip are good.

[0110] The above is a detailed introduction to a flip-chip LED chip and a preparation method thereof provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a flip-chip LED chip, characterized in that: The method for preparing the flip-chip LED chip comprises: forming a patterned lift-off layer on the patterned epitaxial layer; forming a patterned interface improvement layer on the patterned peeling layer, wherein the patterned interface improvement layer comprises a plurality of interface improvement blocks, and the cross-sectional width of the interface improvement blocks gradually increases in a direction in which the interface improvement layer is away from the peeling layer; forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, wherein the reflective layer on the patterned interface improvement layer is spaced apart from the reflective layer on the patterned epitaxial layer, and the reflective layer is a Bragg reflector; performing an etching process on the patterned peeling layer so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer; Wherein, in the step of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, the reflective layer on the patterned epitaxial layer has a plurality of openings, and the patterned stripping layer is arranged in the plurality of openings, wherein in the direction in which the interface improvement layer is away from the stripping layer, the cross-sectional width of the opening gradually increases.

2. The method for preparing a flip-chip LED chip according to claim 1, characterized in that: The step of forming a patterned interface improvement layer on the patterned release layer comprises: forming a positive photoresist layer on the patterned epitaxial layer and the patterned lift-off layer; Partially exposing the positive photoresist layer by using an exposure device disposed on a side of the positive photoresist layer away from the patterned stripping layer; Cleaning the positive photoresist layer to form a patterned positive photoresist layer, wherein the positive photoresist layer has a plurality of through holes, and the cross-sectional widths of the through holes increase in sequence in a direction from the interface improvement layer away from the stripping layer; Using the patterned positive photoresist layer as a mask, an interface improvement material is deposited to form a patterned interface improvement layer on the patterned stripping layer.

3. The method for preparing a flip-chip LED chip according to claim 1, characterized in that: In the step of forming a patterned lift-off layer on the patterned epitaxial layer, the lift-off layer is an aluminum oxide layer; In the step of forming a patterned interface improvement layer on the patterned release layer, the patterned interface improvement layer is an aluminum metal layer; The step of etching the patterned stripping layer so that the patterned interface improvement layer together with the reflective layer on the patterned interface improvement layer are stripped from the patterned epitaxial layer includes etching the patterned stripping layer using ammonia water with a concentration of 10% to 30%.

4. The method for preparing a flip-chip LED chip according to claim 1, characterized in that: In the step of forming a patterned lift-off layer on the patterned epitaxial layer, the patterned lift-off layer has a first thickness; In the step of forming a patterned interface improvement layer on the patterned release layer, the patterned interface improvement layer has a second thickness; Wherein, the second thickness is greater than the first thickness.

5. The method for preparing a flip-chip LED chip according to claim 1, characterized in that: In the step of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, the reflective layer on the patterned epitaxial layer includes a first sub-reflective layer to an nth sub-reflective layer stacked sequentially on the patterned epitaxial layer, where n is greater than or equal to 2, wherein each of the first sub-reflective layer to the nth sub-reflective layer has an inclined interface on a side facing the opening, and the lengths of the inclined interface from the first sub-reflective layer to the nth sub-reflective layer increase sequentially.

6. The method for preparing a flip-chip LED chip according to claim 5, characterized in that: In the step of forming a reflective layer on the patterned epitaxial layer and the patterned interface improvement layer, the sidewall of the opening is the inclined interface of the nth sub-reflective layer.

7. The method for preparing a flip-chip LED chip according to claim 1, characterized in that: Before the step of forming a patterned lift-off layer on the patterned epitaxial layer, the method further comprises: Forming an epitaxial layer on a substrate, wherein the epitaxial layer includes a first semiconductor layer, a light emitting layer, and a second semiconductor layer sequentially stacked on the substrate; forming a transparent conductive layer on the epitaxial layer; Performing patterning on the transparent conductive layer to form a patterned transparent conductive layer; The second semiconductor layer and the light emitting layer in the epitaxial layer are patterned to form a patterned epitaxial layer.

8. The method for preparing a flip-chip LED chip according to claim 7, characterized in that: After the step of etching the patterned peeling layer so that the patterned interface improvement layer and the reflective layer on the patterned interface improvement layer are peeled off from the patterned epitaxial layer, the method further includes: A patterned electrode layer is formed on the patterned epitaxial layer, wherein the patterned electrode layer includes a plurality of electrodes, and each of the electrodes is surrounded by a reflective layer on the patterned epitaxial layer.

9. A flip-chip LED chip, characterized in that: The flip-chip LED chip is prepared by the method for preparing a flip-chip LED chip according to claim 6, wherein the flip-chip LED chip comprises a patterned epitaxial layer and a reflective layer arranged on the patterned epitaxial layer, wherein the reflective layer on the patterned epitaxial layer has a plurality of openings, wherein electrodes are arranged in the openings, wherein the cross-sectional width of the openings gradually increases in the direction in which the reflective layer moves away from the patterned epitaxial layer; the reflective layer on the patterned epitaxial layer comprises a first sub-reflective layer to an nth sub-reflective layer sequentially stacked on the patterned epitaxial layer, wherein n is greater than or equal to 2, wherein each of the first sub-reflective layer to the nth sub-reflective layer has an inclined interface on a side facing the opening, and the lengths of the inclined interface of the first sub-reflective layer to the inclined interface of the nth sub-reflective layer increase sequentially; and the sidewall of the opening is the inclined interface of the nth sub-reflective layer.

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