A kind of automotive grade light emitting diode chip and its preparation method

Abstract

The present application provides an automotive-grade light-emitting diode chip and a method for preparing the same. The method for preparing the automotive-grade light-emitting diode chip includes: forming a patterned light-emitting epitaxial layer; forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer; wherein the steps of forming the patterned conductive reflective layer and the patterned conductive protective layer on the light-emitting epitaxial layer include: forming a patterned photoresist layer on one side of the light-emitting epitaxial layer; using the photoresist layer as a mask and adopting an evaporation coating method to form a patterned conductive reflective layer; using the photoresist layer as a mask and adopting a sputtering coating method to form a patterned conductive protective layer covering the conductive reflective layer on the conductive reflective layer. The present application can prepare a conductive protective layer with good coating properties for the conductive reflective layer using only one photomask, which not only reduces the production cost, but also improves the reliability of the automotive-grade light-emitting diode chip.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and specifically to an automotive-grade light-emitting diode chip and a method for preparing the same. Background Art

[0002] Light Emitting Diode (LED) chips are semiconductor components that emit light through the recombination of electrons and holes. They have the advantages of low energy consumption, small size, long life, good stability, fast response, and stable luminous wavelength. They are currently widely used in daily lighting, automobiles, displays, medical treatment, optical communications and other fields.

[0003] Taking the automotive field as an example, the application of LED chips in automobiles includes automotive lighting, turn signals, signal lights, etc., and the grade of LED chips should meet the requirements of automotive grade. Compared with consumer-grade LED chips and industrial-grade LED chips, automotive-grade LED chips have stricter requirements on optoelectronic performance and / or reliability. In the related art, in order to make the LED chip meet the optoelectronic performance requirements of automotive-grade LED chips, a flip-chip LED chip is generally used, and a silver mirror structure with excellent reflection effect is set in the flip-chip LED chip to improve the luminous brightness of the flip-chip LED chip. However, the applicant found in internal research that the metallic silver in the silver mirror structure is prone to silver migration, thereby reducing the reliability of the LED chip. At present, the silver migration phenomenon is generally improved by covering the top of the silver mirror structure with a protective layer, but in order to improve the anti-silver migration ability of the protective layer, the protective layer needs to completely cover the silver mirror structure. Correspondingly, the pattern area of ​​the protective layer needs to be larger than the pattern area of ​​the silver mirror structure, that is, the pattern design of the protective layer is different from the pattern design of the silver mirror structure, which requires the use of two masks to form the silver mirror structure and the protective layer respectively, resulting in high manufacturing costs of flip-chip LED chips.

[0004] Therefore, how to take into account the coating effect of the protective layer on the silver mirror structure to ensure the reliability of the LED chip while reducing the production cost is a technical problem that technicians in this field continue to solve. Summary of the invention

[0005] The present application provides an automotive-grade light-emitting diode chip and a method for preparing the same, which can effectively solve the problem in the related art that it is difficult to reduce the production cost while taking into account the coating effect of the protective layer in the LED chip on the silver mirror structure.

[0006] In a first aspect, the present application provides an automotive-grade light-emitting diode chip and a method for preparing the same. The method for preparing the automotive-grade light-emitting diode chip comprises the following steps:

[0007] forming a patterned light-emitting epitaxial layer;

[0008] forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, wherein the conductive reflective layer includes silver, and the conductive protective layer does not include silver;

[0009] Wherein, the step of forming a patterned conductive reflective layer and a patterned conductive protective layer on the light-emitting epitaxial layer comprises:

[0010] forming a patterned photoresist layer on one side of the light-emitting epitaxial layer;

[0011] Using the photoresist layer as a mask, forming a patterned conductive reflective layer by evaporation coating;

[0012] The photoresist layer is used as a mask and a sputtering coating method is adopted to form a patterned conductive protection layer covering the conductive reflective layer on the conductive reflective layer.

[0013] Optionally, in the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer, the patterned photoresist layer includes an opening, and a cross-sectional width of the opening decreases sequentially in a direction in which the photoresist layer is away from the light-emitting epitaxial layer.

[0014] Optionally, in the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer, the patterned photoresist layer has a first thickness;

[0015] In the step of forming a patterned conductive reflective layer by using the photoresist layer as a mask and adopting an evaporation coating method, the patterned conductive reflective layer has a second thickness;

[0016] In the step of forming a patterned conductive protective layer covering the conductive reflective layer on the conductive reflective layer by sputtering using the photoresist layer as a mask, the patterned conductive protective layer has a third thickness;

[0017] The first thickness is greater than the sum of the second thickness and the third thickness.

[0018] Optionally, the third thickness is greater than the second thickness.

[0019] Optionally, in the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer, the angle between the side wall of the opening and the normal perpendicular to the photoresist layer is greater than or equal to 55°; wherein the first thickness is two to five times the sum of the second thickness and the third thickness.

[0020] Optionally, the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer includes:

[0021] Forming a negative photoresist layer on one side of the light-emitting epitaxial layer, wherein the thickness of the photoresist layer is 3 microns to 5 microns;

[0022] Performing a first baking on the photoresist layer, wherein the first baking temperature is 85° C. to 95° C., and the first baking time is 80 seconds to 100 seconds;

[0023] The local area of ​​the negative photoresist layer is exposed by using an exposure device arranged on the side of the photoresist layer away from the light-emitting epitaxial layer, wherein the exposure energy is controlled at 180 mj / cm 2 Up to 200mj / cm 2 ;

[0024] The photoresist layer is developed and baked for a second time to form a patterned photoresist layer, wherein the development time is controlled to be between 60 seconds and 80 seconds, the temperature of the second baking is between 100° C. and 110° C., and the time of the second baking is between 110 seconds and 130 seconds.

[0025] Optionally, the step of forming a patterned light-emitting epitaxial layer includes:

[0026] forming a light-emitting epitaxial layer on one side of a growth substrate;

[0027] forming a current spreading layer on the light emitting epitaxial layer;

[0028] Using a photomask to form a patterned current spreading layer and a patterned light-emitting epitaxial layer;

[0029] The step of forming a patterned current spreading layer and a patterned light-emitting epitaxial layer by using a photomask comprises:

[0030] forming a positive photoresist film on the current spreading layer and baking the film;

[0031] exposing a local area of ​​the positive photoresist film;

[0032] Developing and baking the positive photoresist film to form a mesa photolithography pattern;

[0033] Etching the current spreading layer using the mesa photolithography pattern to form a patterned current spreading layer;

[0034] Etching the light-emitting epitaxial layer using the mesa photolithography pattern to remove the second type semiconductor layer and the multi-quantum well layer not covered by the mesa photolithography pattern, thereby forming a patterned light-emitting epitaxial layer;

[0035] removing the mesa photolithography pattern;

[0036] The method of etching the current spreading layer using the mesa photolithography pattern is wet etching, and the method of etching the light-emitting epitaxial layer using the mesa photolithography pattern is reactive coupled plasma etching.

[0037] Optionally, after the step of forming the patterned light-emitting epitaxial layer and before the step of forming the patterned conductive reflective layer and the patterned conductive protective layer on one side of the light-emitting epitaxial layer, the method further includes the following steps: forming a patterned current blocking layer on one side of the light-emitting epitaxial layer;

[0038] Wherein, the step of forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer comprises:

[0039] forming a patterned photoresist layer on a surface of the current blocking layer on a side away from the light-emitting epitaxial layer;

[0040] Using the photoresist layer as a mask, etching a local area of ​​the current blocking layer to reduce the thickness of the current blocking layer in the local area to form a groove structure;

[0041] Using the photoresist layer as a mask, forming a patterned conductive reflective layer by evaporation coating;

[0042] The photoresist layer is used as a mask and a sputtering coating method is adopted to form a patterned conductive protection layer covering the conductive reflective layer on the conductive reflective layer.

[0043] Optionally, after the step of forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, the method further includes the following steps:

[0044] forming a patterned first passivation layer on one side of the conductive protection layer;

[0045] forming a patterned separation metal layer on one side of the first passivation layer;

[0046] forming a patterned second passivation layer on one side of the separation metal layer;

[0047] forming a patterned electrode layer on one side of the second passivation layer;

[0048] The growth substrate is thinned.

[0049] In a second aspect, the present application provides an automotive-grade light-emitting diode chip, wherein the automotive-grade light-emitting diode chip is prepared by any of the above-mentioned methods for preparing an automotive-grade light-emitting diode chip, wherein the automotive-grade light-emitting diode chip comprises:

[0050] light emitting epitaxial layer;

[0051] A conductive reflective layer, disposed on one side of the light-emitting epitaxial layer, wherein the conductive reflective layer comprises silver;

[0052] A conductive protective layer covers the conductive reflective layer, and the conductive protective layer does not include silver.

[0053] The present application provides a vehicle-grade light-emitting diode chip and a method for preparing the same. The method for preparing the vehicle-grade light-emitting diode chip comprises the following steps: forming a patterned light-emitting epitaxial layer; forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, wherein the conductive reflective layer comprises silver and the conductive protective layer does not comprise silver; wherein the steps of forming the patterned conductive reflective layer and the patterned conductive protective layer on the light-emitting epitaxial layer comprise: forming a patterned photoresist layer on one side of the light-emitting epitaxial layer; using the photoresist layer as a mask, forming a patterned conductive reflective layer by evaporation coating; using the photoresist layer as a mask, forming a patterned conductive protective layer covering the conductive reflective layer on the conductive reflective layer by sputtering coating. The present application utilizes the characteristics of different film-forming ranges of evaporation coating and sputtering coating under the same photoresist mask, and only uses one photomask to effectively reduce the production and manufacturing cost, thereby preparing a conductive protective layer with good coating properties for the conductive reflective layer and improving the reliability of the vehicle-grade light-emitting diode chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] 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.

[0055] Figure 1 A schematic flow chart of a method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0056] Figure 2 A schematic cross-sectional view of an automotive-grade light-emitting diode chip provided for some embodiments of the present application.

[0057] Figure 3 A schematic flow chart of step S10 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0058] Figure 4 A cross-sectional schematic diagram corresponding to step S11 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0059] Figure 5 A cross-sectional schematic diagram corresponding to step S12 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0060] Figure 6 A cross-sectional schematic diagram corresponding to step S13 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0061] Figure 7 A cross-sectional schematic diagram corresponding to step S20 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0062] Figure 8 A schematic flow chart of step S30 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0063] Fig. 9 A cross-sectional schematic diagram corresponding to step S31 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0064] Fig.10 A cross-sectional schematic diagram corresponding to step S32 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0065] Fig.11 A cross-sectional schematic diagram corresponding to step S33 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0066] Fig.12 A cross-sectional schematic diagram corresponding to step S34 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0067] Fig.13 for Fig.12 A partial enlarged view of the A1 area in the middle.

[0068] Fig.14 A cross-sectional schematic diagram corresponding to step S35 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0069] Fig.15 A cross-sectional schematic diagram corresponding to step S40 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0070] Fig.16 A schematic cross-sectional view corresponding to step S50 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0071] Fig.17 A cross-sectional schematic diagram corresponding to step S60 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0072] Fig.18A cross-sectional schematic diagram corresponding to step S70 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0073] Fig.19 A cross-sectional schematic diagram corresponding to step S80 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application.

[0074] Description of reference numerals:

[0075] Growth substrate 100; photoresist layer 200; opening 201; light-emitting epitaxial layer 10; first type semiconductor layer 11; multi-quantum well layer 12; second type semiconductor layer 13; current spreading layer 20; current blocking layer 30; through hole 31; groove structure 32; side wall 321 of the groove structure; conductive reflective layer 40; side wall 41 of the conductive reflective layer; conductive protective layer 50; side wall 51 of the conductive protective layer; first passivation layer 60; separation metal layer 70; second passivation layer 80; electrode layer 90; first type electrode 91; second type electrode 92; normal L1 perpendicular to the photoresist layer; gap M1. DETAILED DESCRIPTION

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] In a first aspect, the present application provides a method for preparing an automotive-grade light-emitting diode chip, which comprises the following steps: forming a patterned light-emitting epitaxial layer; forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, wherein the conductive reflective layer comprises silver and the conductive protective layer does not comprise silver; wherein the steps of forming a patterned conductive reflective layer and a patterned conductive protective layer on the light-emitting epitaxial layer comprise: forming a patterned photoresist layer on one side of the light-emitting epitaxial layer; using the photoresist layer as a mask and adopting an evaporation coating method to form a patterned conductive reflective layer; using the photoresist layer as a mask and adopting a sputtering coating method to form a patterned conductive protective layer covering the conductive reflective layer on the conductive reflective layer.

[0081] In the method for preparing the automotive-grade light-emitting diode chip provided by the present application, the patterned photoresist layer serves as a mask (or photomask) for forming the conductive reflective layer and the conductive protective layer. The present application creatively utilizes the characteristics of different film-forming ranges of evaporation coating and sputtering coating under the same photoresist mask, and prepares and forms a conductive reflective layer and a conductive protective layer with different film-forming areas when only one photomask is used, and enables the conductive protective layer to well cover the conductive reflective layer, which effectively reduces the production cost of automotive-grade light-emitting diode chips and improves the reliability of automotive-grade light-emitting diode chips.

[0082] It should be noted that the conductive protective layer corresponds to the protective layer in the related art, and the conductive reflective layer corresponds to the silver mirror structure in the related art. Therefore, the present application can take into account the coating effect of the protective layer on the silver mirror structure to ensure the reliability of the LED chip while reducing the production cost.

[0083] Figure 1 A schematic flow chart of a method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application; Figure 2 A cross-sectional diagram of an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 1 and Figure 2As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S10, and step S10 includes: forming a patterned light-emitting epitaxial layer 10 on one side of the growth substrate 100.

[0084] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S20, and step S20 includes: forming a patterned current blocking layer 30 on one side of the light-emitting epitaxial layer 10.

[0085] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S30, and step S30 includes: forming a patterned conductive reflective layer 40 and a patterned conductive protective layer 50 on one side of the light-emitting epitaxial layer 10.

[0086] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S40, and step S40 includes: forming a patterned first passivation layer 60 on one side of the conductive protection layer 50.

[0087] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S50, and step S50 includes: forming a patterned separation metal layer 70 on one side of the first passivation layer 60.

[0088] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S60, and step S60 includes: forming a patterned second passivation layer 80 on one side of the separation metal layer 70.

[0089] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S70, and step S70 includes: forming a patterned electrode layer 90 on one side of the second passivation layer 80.

[0090] Reference Figure 1 and Figure 2 As shown, in some embodiments of the present application, the method for preparing the automotive-grade light-emitting diode chip includes step S80, and step S80 includes: thinning the growth substrate 100.

[0091] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, after steps S10 to S80, the prepared automotive-grade light-emitting diode chip can achieve normal light emission while having the advantages of low preparation cost and high reliability.

[0092] Figure 3 A flow chart of step S10 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. In some embodiments of the present application, step S10 includes step S11, step S12, and step S13, wherein step S11 includes: forming a light-emitting epitaxial layer 10 on one side of a growth substrate 100; step S12 includes: forming a current spreading layer 20 on the light-emitting epitaxial layer 10; step S13 includes: forming a patterned current spreading layer 20 and a patterned light-emitting epitaxial layer 10 using a photomask.

[0093] In the method for preparing the automotive-grade light-emitting diode chip provided in the embodiment of the present application, the patterned current expansion layer 20 can increase the current path, reduce the on-resistance, realize current expansion, and further reduce the current density directly below the electrode, so that the current is evenly distributed in the device area of ​​the automotive-grade light-emitting diode chip, greatly improving the light extraction efficiency of the automotive-grade light-emitting diode chip. In addition, by using a mask to form the patterned current expansion layer 20 and the patterned light-emitting epitaxial layer 10, the present application can simplify the film forming process of the light-emitting epitaxial layer 10 and the current expansion layer 20, thereby reducing the production and preparation cost of automotive-grade light-emitting diodes.

[0094] Figure 4 A cross-sectional schematic diagram corresponding to step S11 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 3 and Figure 4 As shown, in some embodiments of the present application, step S11 includes: forming a light-emitting epitaxial layer 10 on one side of a growth substrate 100, wherein the light-emitting epitaxial layer 10 includes a first type semiconductor layer 11, a multi-quantum well layer 12, and a second type semiconductor layer 13 stacked in sequence on one side of the growth substrate 100.

[0095] In some embodiments of the present application, in step S11, the growth substrate 100 is a sapphire substrate.

[0096] In some embodiments of the present application, in step S11, a gallium nitride-based first-type semiconductor layer 11, a multi-quantum well layer 12, and a second-type semiconductor layer 13 may be grown on the growth substrate 100 by using an organic metal chemical vapor deposition method (full name in English: Metal Organic Chemical Vapor Deposition, abbreviated as: MOCVD), wherein the first-type semiconductor layer 11 is one of an N-type semiconductor layer and a P-type semiconductor layer, and the second-type semiconductor layer 13 is the other of an N-type semiconductor layer and a P-type semiconductor layer. Exemplarily, the first-type semiconductor layer 11 is an N-type semiconductor layer, and the second-type semiconductor layer 13 is a P-type semiconductor layer.

[0097] Figure 5 A cross-sectional schematic diagram corresponding to step S12 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 3 and Figure 5 As shown, in some embodiments of the present application, step S12 includes: forming a current spreading layer 20 on a surface of the second type semiconductor layer 13 in the light emitting epitaxial layer 10 which is away from the growth substrate 100 .

[0098] In some embodiments of the present application, in step S12, the current spreading layer 20 is a transparent conductive layer, such as an indium tin oxide (English full name: Indium Tin Oxide, abbreviated as: ITO) layer. The current spreading layer 20 can be formed by sputtering coating. The thickness of the current spreading layer 20 can be 100 angstroms to 1300 angstroms.

[0099] Figure 6 A cross-sectional schematic diagram corresponding to step S13 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 3 and Figure 6 As shown, in some embodiments of the present application, step S13 includes: forming a patterned current spreading layer 20 and a patterned light emitting epitaxial layer 10 by using a photomask.

[0100] In some embodiments of the present application, step S13 includes: forming a positive photoresist film on the current spreading layer 20 and baking it; exposing a local area of ​​the positive photoresist film; developing and baking the positive photoresist film to form a mesa photolithography pattern; etching the current spreading layer 20 using the mesa photolithography pattern to form a patterned current spreading layer 20; etching the light-emitting epitaxial layer 10 using the mesa photolithography pattern to etch away the second type semiconductor layer 13 and the multi-quantum well layer 12 not covered by the mesa photolithography pattern to form A patterned light-emitting epitaxial layer 10; removing the mesa photolithography pattern; wherein the method of etching the current spreading layer 20 using the mesa photolithography pattern is wet etching, and the method of etching the light-emitting epitaxial layer 10 using the mesa photolithography pattern is reactive coupled plasma etching, wherein the side etching effect of wet etching on the indium tin oxide layer is greater than the side etching effect of reactive coupled plasma etching, and the current spreading layer 20 and the light-emitting epitaxial layer 10 with different patterned structures can be prepared by using only one mask and only the mesa photolithography pattern.

[0101] In some embodiments of the present application, in step S13 , the area of ​​the patterned current spreading layer 20 is smaller than the area of ​​the patterned light emitting epitaxial layer 10 .

[0102] Figure 7 This is a cross-sectional schematic diagram corresponding to step S20 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 7 As shown, in some embodiments of the present application, step S20 includes: forming a current blocking layer 30 on one side of the light-emitting epitaxial layer 10; forming a blocking layer photolithography pattern on the current blocking layer 30; etching the current blocking layer 30 using the blocking layer photolithography pattern to etch away the current blocking layer 30 not covered by the blocking layer photolithography pattern to form a patterned current blocking layer 30; and removing the blocking layer photolithography pattern.

[0103] In some embodiments of the present application, in step S20 , the patterned current blocking layer 30 includes a plurality of through holes 31 , and the patterned current blocking layer 30 can prevent current from flowing in unnecessary paths, thereby improving current utilization efficiency.

[0104] In some embodiments of the present application, in step S20 , the material of the current blocking layer 30 may be silicon oxide.

[0105] In some embodiments of the present application, in step S20, the thickness of the current blocking layer 30 is 210 nanometers to 400 nanometers, or 1100 nanometers to 1300 nanometers. Preferably, the thickness of the current blocking layer 30 is 1100 nanometers to 1300 nanometers, so as to thicken the current blocking layer 30, so as to facilitate further patterning of the current blocking layer 30 in subsequent processes to realize the design of the groove structure 32, and the specific role of the groove structure 32 will be described below.

[0106] Figure 8 This is a flow chart of step S30 in the method for preparing a vehicle-grade light-emitting diode chip provided in some embodiments of the present application. Figure 8 As shown, step S30 includes step S31, step S33 and step S34, step S31 includes: forming a patterned photoresist layer 200 on one side of the light-emitting epitaxial layer 10; step S33 includes: using the photoresist layer 200 as a mask, adopting an evaporation coating method to form a patterned conductive reflective layer 40; step S34 includes: using the photoresist layer 200 as a mask, adopting a sputtering coating method to form a patterned conductive protective layer 50 covering the conductive reflective layer 40 on the conductive reflective layer 40.

[0107] Fig. 9 A cross-sectional schematic diagram corresponding to step S31 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 8 and Fig. 9 As shown, in some embodiments of the present application, step S31 includes: forming a patterned photoresist layer 200 on a surface of the current blocking layer 30 on a side away from the light-emitting epitaxial layer 10 .

[0108] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, after step S20 , step S31 is performed to make the carrier film layer of the patterned photoresist layer 200 a current blocking layer 30 .

[0109] In some embodiments of the present application, in step S31 , the patterned photoresist layer 200 includes an opening 201 , and in a direction in which the photoresist layer 200 is away from the light-emitting epitaxial layer 10 , the cross-sectional width of the opening 201 decreases sequentially.

[0110] In the method for preparing the automotive-grade light-emitting diode chip provided in the embodiment of the present application, the opening 201 of the patterned photoresist layer 200 is used to pass the film-forming particles during the subsequent coating process of the conductive reflective layer 40 and the conductive protective layer 50, that is, the structural design of the opening 201 of the patterned photoresist layer 200 will directly affect the subsequent film-forming range of the conductive reflective layer 40 and the conductive protective layer 50. The applicant found in internal research that when the cross-sectional width of the opening 201 decreases successively in the direction of the photoresist layer 200 away from the light-emitting epitaxial layer 10, the opening 201 is horn-shaped, and the opening 201 can not only play the role of limiting the main film-forming area of ​​the conductive reflective layer 40 and the conductive protective layer 50, but also give full play to the film-forming difference between evaporation coating and sputtering coating, so that the conductive protective layer 50 of the sputtering coating can be more fully diffused, thereby forming a conductive protective layer 50 with high film-forming accuracy and good coating of the conductive reflective layer 40, thereby improving the reliability of the automotive-grade light-emitting diode chip.

[0111] In some embodiments of the present application, in step S31, the patterned photoresist layer 200 has a first thickness; in step S33, the patterned conductive reflective layer 40 has a second thickness; in step S34, the patterned conductive protective layer 50 has a third thickness; wherein the first thickness is greater than the second thickness and the third thickness.

[0112] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, when the sum of the film thicknesses of the patterned conductive reflective layer 40 and the patterned conductive protective layer 50 is greater than or equal to the patterned photoresist layer 200, after the film formation is completed, adhesion will occur between the conductive protective layer 50 and the side wall of the opening 201, thereby reducing the film formation quality and increasing the difficulty of the subsequent stripping process. Therefore, the present application makes the first thickness greater than the second thickness and the third thickness.

[0113] In some embodiments of the present application, the third thickness is greater than the second thickness.

[0114] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, the applicant discovered in internal research that when the thickness of the conductive reflective layer 40 is too large, the film-forming diffusion distance of the conductive protective layer 50 will be squeezed, thereby causing the sputtered conductive protective layer 50 to be unable to fully diffuse, resulting in a decrease in the coating ability of the conductive protective layer 50 on the conductive reflective layer 40. Therefore, the present application makes the third thickness greater than the second thickness.

[0115] In some embodiments of the present application, in step S31, the angle between the sidewall of the opening 201 and the normal L1 perpendicular to the photoresist layer 200 is greater than or equal to 55°; the first thickness is two to five times the sum of the second thickness and the third thickness.

[0116] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, the applicant has found in internal research that the film-forming diffusion angle of the evaporated coating is smaller than the film-forming diffusion angle of the sputtered coating, and the film-forming diffusion angle of the evaporated coating does not exceed 80°, and the film-forming diffusion angle of the sputtered coating does not exceed 110°. Accordingly, the present application makes the angle between the side wall of the opening 201 and the normal perpendicular to the photoresist layer 200 greater than or equal to 55°, thereby avoiding the limitation on the film-forming diffusion range group of the sputtered coating caused by the small inclination angle of the side wall of the opening 201, expanding the coating range of the conductive protective layer 50, thereby improving the coverage of the conductive protective layer 50 on the conductive reflective layer 40, and improving the reliability of the automotive-grade light-emitting diode chip.

[0117] In addition, since the angle between the side wall of the opening 201 and the normal line perpendicular to the photoresist layer 200 is greater than or equal to 55°, when the film-forming particles pass through the opening 201 and are plated below the side wall of the opening 201, it is possible to avoid as much as possible the adhesion between the film-forming particles and the side wall of the opening 201. On this basis, since the first thickness is two to five times the sum of the second thickness and the third thickness, it is possible to ensure that the film-forming particles are fully diffused in the space defined by the opening 201, avoiding the problem that the film diffusion distance is less than the preset value due to the increase in the film thickness, and the coating of the conductive protective layer 50 on the conductive reflective layer 40 is reduced.

[0118] In some embodiments of the present application, step S31 includes: forming a negative photoresist layer 200 on one side of the light-emitting epitaxial layer 10, wherein the thickness of the photoresist layer 200 is 3 microns to 5 microns; performing a first baking on the photoresist layer 200, wherein the temperature of the first baking is 85°C to 95°C, and the time of the first baking is 80 seconds to 100 seconds; using an exposure device arranged on the side of the photoresist layer 200 away from the light-emitting epitaxial layer 10, exposing a local area of ​​the negative photoresist layer 200, wherein the exposure energy is controlled at 180mj / cm 2 Up to 200mj / cm 2; The photoresist layer 200 is developed and baked for a second time to form a patterned photoresist layer 200, wherein the development time is controlled at 60 seconds to 80 seconds, the temperature of the second baking is 100°C to 110°C, and the time of the second baking is 110 seconds to 130 seconds.

[0119] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, since the thickness of the photoresist layer 200 is 3 microns to 5 microns, it is possible to ensure that the photoresist layer 200 has sufficient thickness to form an opening 201 with a sidewall having a predetermined inclination angle.

[0120] Furthermore, in the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, by adopting a negative photoresist layer 200 of a specific thickness, a first baking at a specific temperature, and using an exposure device arranged on the side of the photoresist layer 200 away from the light-emitting epitaxial layer 10, a local area of ​​the negative photoresist layer 200 is exposed to a specific exposure energy, so that the residual film rate of the negative photoresist layer 200 at different exposure depths can be different, and then after development and a second baking, an opening 201 with a predetermined inclination angle is formed.

[0121] Fig.10 A schematic flow chart of step S32 in the method for preparing a vehicle-grade light-emitting diode chip provided in some embodiments of the present application. Figure 8 and Fig.10 As shown, step S32 includes: using the photoresist layer 200 as a mask, etching a local area of ​​the current blocking layer 30 to reduce the thickness of the current blocking layer 30 in the local area to form a groove structure 32.

[0122] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, in the subsequent steps S33 and S34 after step S31, the patterned photoresist layer 200 is used as a mask for forming a patterned conductive reflective layer 40 and a patterned conductive protective layer 50, and step S32 makes the patterned photoresist layer 200 also serve as a mask for forming a groove structure 32 in the current blocking layer 30, thereby achieving further patterning of the current blocking layer 30 without increasing the number of masking times and reducing the production cost as much as possible.

[0123] The present application forms the groove structure 32, and then utilizes the groove structure 32 to form a gap between the film forming platform (i.e., the bottom of the groove structure 32) and the photoresist layer 200, and then utilizes the gap as a space for forming the conductive reflective layer 40 and the conductive protective layer 50, thereby increasing the film forming diffusion distance of the conductive reflective layer 40 and the conductive protective layer 50 during film forming, and avoiding adhesion between the conductive reflective layer 40 and the conductive protective layer 50 and the side wall of the opening 201 as much as possible, so as to make it easier to peel off the subsequent redundant conductive reflective film (not shown in the figure) and the redundant conductive protective film (not shown in the figure), thereby improving the film forming quality and further improving the reliability of the automotive-grade light-emitting diode chip. It should be noted that the redundant conductive reflective film and the conductive reflective layer 40 are formed as one piece, and the redundant conductive protective film and the conductive protective layer 50 are formed as one piece.

[0124] In some implementations of the present application, the etching method for the local area of ​​the current blocking layer 30 is wet etching, and accordingly, the maximum area of ​​the groove structure 32 is not less than the maximum area of ​​the opening 201 .

[0125] In some embodiments of the present application, in step S20, the thickness of the current blocking layer 30 is 1100 nanometers to 1300 nanometers; in step S31, the groove structure 32 is arranged on the side of the multiple through holes 31 after thinning away from the current spreading layer 20, corresponding to the position of the current spreading layer 20.

[0126] It should be noted that, in other embodiments of the present application, step S32 may be omitted. In this case, in step S20, the thickness of the current blocking layer 30 is 210 nanometers to 400 nanometers.

[0127] Fig.11 This is a cross-sectional schematic diagram corresponding to step S33 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 8 and Fig.11 As shown, step S33 includes: using the photoresist layer 200 as a mask, and adopting an evaporation coating method to form a patterned conductive reflective layer 40, wherein the conductive reflective layer 40 includes silver.

[0128] In the preparation method of the automotive-grade LED chip provided in the embodiment of the present application, the patterned conductive reflective layer 40 forms a silver mirror structure to further reflect the light in the automotive-grade LED chip and reflect it to the light-emitting surface of the automotive-grade LED chip, thereby improving the light-emitting efficiency of the automotive-grade LED chip.

[0129] In some embodiments of the present application, in step S33 , the conductive reflective layer 40 includes a titanium metal layer, a silver metal layer, a titanium metal layer and a platinum metal layer stacked in sequence on one side of the light-emitting epitaxial layer 10 .

[0130] In some embodiments of the present application, in step S33 , the thickness of the conductive reflective layer 40 is 300 nanometers to 400 nanometers.

[0131] Fig.12 A cross-sectional schematic diagram corresponding to step S34 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 8 and Fig.12 As shown, step S34 includes: using the photoresist layer 200 as a mask, and adopting a sputtering coating method to form a patterned conductive protection layer 50 covering the conductive reflective layer 40 on the conductive reflective layer 40, wherein the conductive protection layer 50 does not include silver.

[0132] In the method for preparing an automotive-grade light-emitting diode chip provided in an embodiment of the present application, the patterned conductive protective layer 50 is used to protect the silver mirror structure to prevent the migration of silver in the silver mirror structure. Accordingly, the conductive protective layer 50 does not include silver.

[0133] In some embodiments of the present application, the conductive protection layer 50 includes a titanium-tungsten alloy, a platinum metal layer, a titanium-tungsten alloy, a platinum metal layer and a titanium metal layer which are sequentially stacked on one side of the light-emitting epitaxial layer 10 .

[0134] In some embodiments of the present application, in step S33 , the thickness of the conductive protection layer 50 is 450 nanometers to 550 nanometers.

[0135] Fig.13 for Fig.12 A partial enlarged view of the A1 area in the middle. Fig.12 and Fig.13 As shown, the inclination degree of the side wall 41 of the prepared conductive reflective layer 40 compared with the normal line L1 perpendicular to the photoresist layer 200 is the smallest, the inclination degree of the side wall 51 of the prepared conductive protection layer 50 compared with the normal line L1 perpendicular to the photoresist layer 200 is greater than the inclination degree of the side wall 41 of the prepared conductive reflective layer 40 compared with the normal line L1 perpendicular to the photoresist layer 200, and the inclination degree of the side wall of the opening 201 in the prepared photoresist layer 200 compared with the normal line L1 perpendicular to the photoresist layer 200 is the largest.

[0136] In some embodiments of the present application, a gap M1 is formed between the photoresist layer 200 and the conductive protection layer 50 , thereby avoiding adhesion between the conductive protection layer 50 and the photoresist layer 200 , which is beneficial to improving the reliability of automotive-grade light-emitting diode chips.

[0137] In some embodiments of the present application, in the region where the gap M1 is located, the sidewall 51 of the conductive protection layer 50 and the sidewall 321 of the groove structure 32 are respectively located on both sides of the normal L1 perpendicular to the photoresist layer 200. The present application forms the groove structure 32 by wet etching, so that the inclination direction of the sidewall 321 of the groove structure 32 is different from the inclination direction of the sidewall 51 of the conductive protection layer 50, which is conducive to the formation of the gap M1, can avoid the adhesion problem caused by the conductive protection layer 50 completely filling the groove structure 32, and can further improve the reliability of the automotive-grade light-emitting diode chip. Exemplarily, the angle between the sidewall 51 of the conductive protection layer 50 and the sidewall 321 of the groove structure 32 is an obtuse angle.

[0138] Fig.14 A cross-sectional schematic diagram corresponding to step S35 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 8 and Fig.14 As shown, step S30 also includes step S35 , and step S35 includes: removing the photoresist layer 200 .

[0139] In some embodiments of the present application, before removing the photoresist layer 200, the step further includes: removing the redundant conductive reflective film (not shown in the figure) and the redundant conductive protective film (not shown in the figure) by dry stripping. Exemplarily, the conductive reflective layer 40 and the conductive protective layer 50 can be removed and recycled by using an adhesive blue film.

[0140] Fig.15 A cross-sectional schematic diagram corresponding to step S40 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 1 and Fig.15 As shown, the method for preparing an automotive-grade light-emitting diode chip further includes step S40 , and step S40 includes: forming a patterned first passivation layer 60 on one side of the conductive protection layer 50 .

[0141] In some embodiments of the present application, in step S40, the first passivation layer 60 may be formed by plasma enhanced chemical vapor deposition, with a thickness of 900 nanometers to 1100 nanometers, and the material may be silicon oxide.

[0142] Fig.16A cross-sectional schematic diagram corresponding to step S50 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 1 and Fig.16 As shown, the method for preparing an automotive-grade light-emitting diode chip also includes step S50 , and step S50 includes: forming a patterned separation metal layer 70 on one side of the first passivation layer 60 .

[0143] In some embodiments of the present application, in step S50, the functions of the separation metal layer 70 include: providing a platform of equal height for the subsequent formation of the first type electrode 91 and the second type electrode 92, and serving as a transfer electrode.

[0144] Fig.17 This is a cross-sectional schematic diagram corresponding to step S60 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 1 and Fig.17 As shown, the method for preparing an automotive-grade light-emitting diode chip further includes step S60 , and step S60 includes: forming a patterned second passivation layer 80 on one side of the separation metal layer 70 .

[0145] In some embodiments of the present application, in step S60, the second passivation layer 80 may be formed by plasma enhanced chemical vapor deposition, with a thickness of 900 nanometers to 1100 nanometers, and the material may be silicon oxide.

[0146] Fig.18 This is a cross-sectional schematic diagram corresponding to step S70 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 1 and Fig.18 As shown, the method for preparing an automotive-grade light-emitting diode chip also includes step S70 , and step S70 includes: forming a patterned electrode layer 90 on one side of the second passivation layer 80 .

[0147] In some embodiments of the present application, in step S70, the electrode layer 90 includes a first type electrode 91 and a second type electrode 92, the first type electrode 91 is electrically connected to the first type semiconductor layer 11 through a portion of the separation metal layer 70, the second type electrode 92 is electrically connected to the second type semiconductor layer 13 through another portion of the separation metal layer 70, and the surface of the first type electrode 91 is at the same height as the surface of the second type electrode 92.

[0148] Fig.19 This is a cross-sectional schematic diagram corresponding to step S80 in the method for preparing an automotive-grade light-emitting diode chip provided in some embodiments of the present application. Figure 1 and Fig.19As shown, the method for preparing an automotive-grade light-emitting diode chip also includes step S80 , and step S80 includes: thinning the growth substrate 100 .

[0149] Continue to refer to Figure 1 and Figure 2 In the second aspect, the present application also provides an automotive-grade light-emitting diode chip, which is prepared by any of the above-mentioned methods for preparing automotive-grade light-emitting diode chips, wherein the automotive-grade light-emitting diode chip comprises: a light-emitting epitaxial layer 10; a conductive reflective layer 40, which is arranged on one side of the light-emitting epitaxial layer 10, and the conductive reflective layer 40 comprises silver; a conductive protective layer 50, which covers the conductive reflective layer 40, and the conductive protective layer 50 does not include silver.

[0150] In some embodiments of the present application, the automotive-grade light-emitting diode chip further includes: a growth substrate 100, the light-emitting epitaxial layer 10 is arranged on one side of the growth substrate 100; a current spreading layer 20 is arranged on the side of the light-emitting epitaxial layer 10 away from the growth substrate 100; a current blocking layer 30 is arranged on the side of the current spreading layer 20 away from the current spreading layer 20; a first passivation layer 60 is arranged on the side of the conductive protective layer 50 away from the conductive reflective layer 40; a separation metal layer 70 is arranged on the first passivation layer 60 away from the conductive protective layer 50; a second passivation layer 80, arranged on the side of the separation metal layer 70 away from the first passivation layer 60; an electrode layer 90, arranged on the side of the second passivation layer 80 away from the separation metal layer 70, the electrode layer 90 includes a first type electrode 91 and a second type electrode 92, the first type electrode 91 is electrically connected to the first type semiconductor layer 11 in the light emitting epitaxial layer 10 through the separation metal layer 70, and the second type electrode 92 is electrically connected to the second type semiconductor layer 13 in the light emitting epitaxial layer 10 through the separation metal layer 70.

[0151] In some embodiments of the present application, the surface of the first type electrode 91 is flush with the surface of the second type electrode 92 to form an equal-height pad design.

[0152] In some embodiments of the present application, there is a gap M1 between the current blocking layer 30 and the conductive protection layer 50 .

[0153] In summary, the present application provides a vehicle-grade light-emitting diode chip and a method for preparing the same. The method for preparing the vehicle-grade light-emitting diode chip comprises the following steps: forming a patterned light-emitting epitaxial layer; forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, wherein the conductive reflective layer comprises silver and the conductive protective layer does not comprise silver; wherein the steps of forming the patterned conductive reflective layer and the patterned conductive protective layer on the light-emitting epitaxial layer comprise: forming a patterned photoresist layer on one side of the light-emitting epitaxial layer; using the photoresist layer as a mask, forming a patterned conductive reflective layer by evaporation coating; using the photoresist layer as a mask, forming a patterned conductive protective layer covering the conductive reflective layer on the conductive reflective layer by sputtering coating. The present application utilizes the characteristics of different film-forming ranges of evaporation coating and sputtering coating under the same photoresist mask, and prepares a conductive protective layer with good coating properties for the conductive reflective layer while using only one photomask to effectively reduce the production and manufacturing cost, thereby improving the reliability of the vehicle-grade light-emitting diode chip.

[0154] The above is a detailed introduction to an automotive-grade light-emitting diode chip and a preparation method thereof provided in the embodiments 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 ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing an automotive-grade light-emitting diode chip, characterized in that: The method for preparing the automotive-grade light-emitting diode chip comprises the following steps: forming a patterned light-emitting epitaxial layer; forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, wherein the conductive reflective layer includes silver, and the conductive protective layer does not include silver; Wherein, the step of forming a patterned conductive reflective layer and a patterned conductive protective layer on the light-emitting epitaxial layer comprises: forming a patterned photoresist layer on one side of the light-emitting epitaxial layer; Using the photoresist layer as a mask, forming a patterned conductive reflective layer by evaporation coating; Using the photoresist layer as a mask, a patterned conductive protective layer covering the conductive reflective layer is formed on the conductive reflective layer by sputtering; Wherein, in the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer, the patterned photoresist layer includes an opening, and the cross-sectional width of the opening decreases successively in the direction in which the photoresist layer is away from the light-emitting epitaxial layer.

2. The method for preparing an automotive-grade light-emitting diode chip according to claim 1, characterized in that: In the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer, the patterned photoresist layer has a first thickness; In the step of forming a patterned conductive reflective layer by using the photoresist layer as a mask and adopting an evaporation coating method, the patterned conductive reflective layer has a second thickness; In the step of forming a patterned conductive protective layer covering the conductive reflective layer on the conductive reflective layer by sputtering using the photoresist layer as a mask, the patterned conductive protective layer has a third thickness; The first thickness is greater than the sum of the second thickness and the third thickness.

3. The method for preparing an automotive-grade light-emitting diode chip according to claim 2, characterized in that: The third thickness is greater than the second thickness.

4. The method for preparing an automotive-grade light-emitting diode chip according to claim 3, characterized in that: In the step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer, the angle between the sidewall of the opening and the normal line perpendicular to the photoresist layer is greater than or equal to 55°; The first thickness is two to five times the sum of the second thickness and the third thickness.

5. The method for preparing an automotive-grade light-emitting diode chip according to claim 4, characterized in that: The step of forming a patterned photoresist layer on one side of the light-emitting epitaxial layer comprises: Forming a negative photoresist layer on one side of the light-emitting epitaxial layer, wherein the thickness of the photoresist layer is 3 microns to 5 microns; Performing a first baking on the photoresist layer, wherein the first baking temperature is 85° C. to 95° C., and the first baking time is 80 seconds to 100 seconds; The local area of ​​the negative photoresist layer is exposed by using an exposure device arranged on the side of the photoresist layer away from the light-emitting epitaxial layer, wherein the exposure energy is controlled at 180 mj / cm 2 Up to 200mj / cm 2 ; The photoresist layer is developed and baked for a second time to form a patterned photoresist layer, wherein the development time is controlled to be between 60 seconds and 80 seconds, the temperature of the second baking is between 100° C. and 110° C., and the time of the second baking is between 110 seconds and 130 seconds.

6. The method for preparing an automotive-grade light-emitting diode chip according to claim 1, characterized in that: The step of forming a patterned light-emitting epitaxial layer comprises: forming a light-emitting epitaxial layer on one side of a growth substrate; forming a current spreading layer on the light emitting epitaxial layer; Using a photomask to form a patterned current spreading layer and a patterned light-emitting epitaxial layer; The step of forming a patterned current spreading layer and a patterned light-emitting epitaxial layer by using a photomask comprises: forming a positive photoresist film on the current spreading layer and baking the film; exposing a local area of ​​the positive photoresist film; Developing and baking the positive photoresist film to form a mesa photolithography pattern; Etching the current spreading layer using the mesa photolithography pattern to form a patterned current spreading layer; Etching the light-emitting epitaxial layer using the mesa photolithography pattern to remove the second type semiconductor layer and the multi-quantum well layer not covered by the mesa photolithography pattern, thereby forming a patterned light-emitting epitaxial layer; removing the mesa photolithography pattern; The method of etching the current spreading layer using the mesa photolithography pattern is wet etching, and the method of etching the light-emitting epitaxial layer using the mesa photolithography pattern is reactive coupled plasma etching.

7. The method for preparing an automotive-grade light-emitting diode chip according to claim 1, characterized in that: After the step of forming the patterned light-emitting epitaxial layer and before the step of forming the patterned conductive reflective layer and the patterned conductive protective layer on one side of the light-emitting epitaxial layer, the method further includes the following steps: forming a patterned current blocking layer on one side of the light-emitting epitaxial layer; Wherein, the step of forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer comprises: forming a patterned photoresist layer on a surface of the current blocking layer on a side away from the light-emitting epitaxial layer; Using the photoresist layer as a mask, etching a local area of ​​the current blocking layer to reduce the thickness of the current blocking layer in the local area to form a groove structure; Using the photoresist layer as a mask, forming a patterned conductive reflective layer by evaporation coating; The photoresist layer is used as a mask and a sputtering coating method is adopted to form a patterned conductive protection layer covering the conductive reflective layer on the conductive reflective layer.

8. The method for preparing an automotive-grade light-emitting diode chip according to claim 6, characterized in that: After the step of forming a patterned conductive reflective layer and a patterned conductive protective layer on one side of the light-emitting epitaxial layer, the step further includes: forming a patterned first passivation layer on one side of the conductive protection layer; forming a patterned separation metal layer on one side of the first passivation layer; forming a patterned second passivation layer on one side of the separation metal layer; forming a patterned electrode layer on one side of the second passivation layer; The growth substrate is thinned.

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