A method for cutting LED epitaxial wafers

Abstract

This invention discloses a method for dicing LED epitaxial wafers, relating to the field of wafer dicing technology. The method includes: mixing a long-chain copolymer amphoteric buffer resin as component A and an amino-functionalized metal chelate trapping agent as component B to prepare a protective liquid; coating the protective liquid onto the surface of the LED epitaxial wafer to form a liquid film; baking the liquid film to allow the solvent and volatile components to escape, forming a solid protective layer on the surface of the LED epitaxial wafer; dicing the LED epitaxial wafer; and rinsing the diced LED epitaxial wafer to rapidly dissociate the solid protective layer and remove dicing debris and molten metal from the wafer surface. This invention constructs a protective system that combines stress buffering and active trapping functions, effectively dissipating the mechanical shear force generated by high-speed dicing using molecular rheological properties to prevent wafer edge chipping, and achieving thorough water washing and desorption through a hydrophilic-induced swelling and disintegration mechanism, thus avoiding electrode oxidation and residue.

Description

Technical Field

[0001] This invention relates to the field of wafer cutting technology, and more specifically to a cutting method for LED epitaxial wafers. Background Technology

[0002] With the rapid development and integration of semiconductor optoelectronic technology, in typical LED epitaxial wafer manufacturing scenarios, device structures are evolving towards multilayer composite film systems and miniaturized electrodes. This complex wafer structure, when subjected to high-speed mechanical cutting or laser stealth processing, experiences extremely high instantaneous mechanical shear forces and localized thermal shocks at the processing interface. Traditional protective methods, based on physical shielding or single solvent barriers and the principle of linear superposition, are ill-suited to these extreme conditions. Under intense stress transmission and thermal fields, traditional protective layers are prone to brittle fracture or high-temperature carbonization, leading to a surge in the risk of chipping at the wafer dicing edge. Furthermore, they are ineffective in preventing the electrostatic adsorption and reverse adhesion of molten metal slag, resulting in electrode oxidation, short circuits, and cleaning residue problems, severely restricting the yield and electrical reliability of high-precision optoelectronic chips. Summary of the Invention

[0003] The purpose of this invention is to provide a cutting method for LED epitaxial wafers, which solves the problems existing in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides a cutting method for LED epitaxial wafers, comprising the following steps:

[0005] S1. Preparation of Protective Solution: A component is an amphoteric acrylic resin copolymerized from methacrylic acid, polyethylene glycol monomethacrylate, and methacryloyloxyethyltrimethylammonium chloride; B component is a hyperbranched polyamide obtained by melt polycondensation of citric acid and ethylenediamine; Components A and B are weighed and mixed at a mass ratio of 9:1 to 11:1; a volatile alkaline regulator is then added to adjust the pH of the system to 8.3 to 8.7, followed by pH adjustment and viscosity stabilization treatment. The volatile alkaline regulator is ammonia or a water-soluble organic amine with a boiling point below 100℃; deionized water is then added to dilute the solution to a viscosity of 300 to 500 mPa·s, and the solution is then subjected to ultrasonic defoaming treatment to obtain the protective solution.

[0006] S2, Dynamic Coating: The protective liquid obtained in step S1 is coated onto the surface of the LED epitaxial wafer through a gradient spin coating process to form a liquid film;

[0007] S3, Temperature-dependent curing: The liquid film is baked with a gradient temperature increase, which causes the solvent and volatile components in the liquid film to escape and form a solid protective layer on the surface of the LED epitaxial wafer.

[0008] S4. Cutting: Perform mechanical wheel cutting or laser stealth cutting on the LED epitaxial wafer covered with a solid protective layer.

[0009] S5. Phase change cleaning: Use deionized water to rinse the cut LED epitaxial wafer. The rinsing pressure is set to 0.4~0.6MPa. The deionized water environment induces the polymer chain segments to absorb water and swell at a high rate, destroying the dense structure of the solidified film layer, thereby causing the solid protective layer to quickly dissociate and completely detach from the wafer surface, carrying cutting debris and molten metal slag.

[0010] Preferably, component A comprises the following raw materials in parts by weight: 35-45 parts methacrylic acid, 25-35 parts polyethylene glycol monomethacrylate with a number average molecular weight of 400-600, 25-35 parts methacryloyloxyethyltrimethylammonium chloride, 0.2-0.6 parts chain transfer agent, 0.6-1.0 parts initiator, and 380-420 parts deionized water;

[0011] Component B comprises the following raw materials in parts by weight: 18-20 parts citric acid, 6-8 parts ethylenediamine, and 90-110 parts solvent.

[0012] Preferably, the preparation method of component A is as follows: A portion of deionized water is added to a reaction vessel, and an inert gas is introduced for deoxygenation treatment for 20-40 minutes, followed by heating to 70-80°C. Methacrylic acid, polyethylene glycol monomethacrylate, methacryloyloxyethyltrimethylammonium chloride, and the remaining deionized water are mixed to obtain a monomer phase, and the initiator is dissolved to obtain an initiating phase. The monomer phase and the initiating phase are simultaneously added using a double-drop polymerization process, wherein the chain transfer agent is dissolved in the monomer phase and is added starting when the addition reaches 45-55% of the monomer phase, and the addition treatment lasts for 1-2 hours. After the addition is completed, the temperature is raised to 80-90°C, and the mixture is stirred at 250-350 r / min for 3-5 hours. After cooling, the pH is adjusted to neutral to obtain component A. The chain transfer agent is thioglycolic acid, and the dosage is adjusted to 0.2-0.6 parts by weight.

[0013] Preferably, the preparation method of component B is as follows: citric acid is dissolved in anhydrous ethanol solvent, cooled to 0-5°C in an ice bath, and ethylenediamine is slowly added dropwise, controlling the dropping rate to prevent violent exothermic reaction. The mixture is stirred for 30-60 minutes to form an ammonium salt intermediate. The intermediate is then transferred to a rotary evaporator to completely remove the solvent under reduced pressure, yielding a solid ammonium salt intermediate. The solid ammonium salt intermediate is placed in a reaction vessel and heated to 145-155°C under nitrogen protection for melt polycondensation reaction for 3-5 hours. During the reaction, the viscosity of the system is monitored using an online viscometer or stirring power monitor. When the viscosity is detected at a shear rate of 10 s⁻¹, the viscosity is measured. -1When the melt viscosity reaches 60-80 Pa·s under the given conditions, heating should be stopped immediately and the temperature should be rapidly reduced to room temperature to prevent cross-linking and gelation of the system. The resulting product should be placed in anhydrous ethanol and stirred and refluxed in a water bath at 40-50°C, along with ultrasonic dispersion, until completely dissolved. The solid content should be adjusted to 40%-50% to obtain an alcohol-soluble component B solution.

[0014] Preferably, in S1, the specific operation of mixing and blending is as follows: weigh component A and component B at a mass ratio of 9:1 to 11:1 and mix them. Add a volatile alkaline regulator to adjust the pH of the system to 8.3 to 8.7 for pH adjustment and viscosity stabilization treatment. Add deionized water to dilute to a viscosity of 300 to 500 mPa·s. Then perform ultrasonic defoaming treatment for 15 to 25 minutes to obtain a protective solution.

[0015] Ammonia is selected as the volatile alkaline regulator.

[0016] Preferably, in S2, the gradient spin coating process includes three stages:

[0017] First stage: Set the rotation speed to 400~600r / min, spin coat for 4~6s to allow the protective liquid to spread;

[0018] Second stage: Set the rotation speed to 2400~2600 r / min, the acceleration to 400~600 r / min / s, spin coat for 25~35s to form the main film layer;

[0019] Third stage: Set the rotation speed to 2800~3200r / min, spin coat for 4~6s, and remove the glue beads at the edges;

[0020] For LED epitaxial wafers with a surface step height greater than 5μm, after the second stage, a settling process is added for 8~12s. After the thixotropy is established by solvent evaporation, the third stage is then carried out.

[0021] Preferably, in S3, the gradient temperature baking includes:

[0022] S31. Set the temperature to 55~65℃ and bake for 50~70 seconds to remove solvent and prevent boiling over.

[0023] S32. Set the temperature to 85~95℃ and bake for 80~100s to volatilize the alkaline regulator to lower the pH value and induce physical anchoring formation.

[0024] Preferably, in S4, the rotational speed of the mechanical cutting wheel is set to be greater than 30,000 r / min;

[0025] In S5, the rinsing pressure of deionized water is set to 0.4~0.6MPa, utilizing the hydrogen bonding between carboxyl and amino groups in a pH neutral water environment.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] By constructing a flexible protection system with dynamic stress dissipation capabilities, the mechanical stability of wafers under extreme processing conditions is significantly improved. Utilizing the specific spatial configuration and rheological properties of molecular chain segments, it can act as a microscopic lubricant and buffer medium at the moment of contact with the high-speed cutting wheel, effectively dispersing and absorbing high-frequency shear stress. This avoids brittle fracture of hard and brittle substrates caused by stress concentration, overcomes the defects of traditional rigid or purely physical barrier materials that are easily broken under high-speed shearing, ensures the flatness of the cutting edge, greatly reduces the loss of effective light-emitting area of ​​the chip due to edge chipping, and significantly improves the appearance yield.

[0028] By introducing specific chemical action sites into the protection system, it can actively adsorb and encapsulate the molten metal slag generated by the electrode layer during the cutting process, effectively shielding the electrostatic adsorption effect and preventing the reverse adhesion and oxidation of conductive debris on the chip surface. It has environmentally responsive phase change dissociation characteristics, which can quickly release the physical anchoring between molecules in a specific water washing environment, completely carrying away the encapsulated debris and carbonization products, achieving zero surface residue under mild cleaning conditions, and ensuring the wire bonding strength of subsequent packaging processes.

[0029] It possesses excellent morphological adaptability and production tolerance. For complex wafer structures with large height differences on the surface, it can quickly establish structural support at the edge of the step through precise control of rheological properties, achieving conformal coverage and eliminating the protection blind spots in deep trench structures of traditional coating processes. At the same time, through unique pH adjustment and viscosity stabilization treatment strategies, it maintains excellent chemical stability during the storage stage, while rapidly forming a high-strength protective film during the coating and curing stage. This not only extends the industrial applicability of the material, but also ensures the stability and consistency of continuous large-scale production. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram illustrating the state changes of each process step in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram illustrating the molecular swelling and desorption principle of the protective system of the present invention. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise stated, all chemical reagents used in this embodiment are commercially available analytical grade products;

[0035] The polyethylene glycol monomethacrylate in component A is selected from oligomer monomers with a number average molecular weight of 400-600. Side chains in this molecular weight range can provide suitable chain segment movement freedom after curing, achieving the best stress dissipation effect. If the molecular weight is too low, the flexibility is insufficient; if the molecular weight is too high, the crystallinity is enhanced, which is not conducive to water washing and removal.

[0036] The initiator is a water-soluble initiator, preferably one or more of ammonium persulfate, potassium persulfate, or 2,2'-diamidinyl-2,2'-azopropane dihydrochloride;

[0037] Unless otherwise specified, the solvent in component B refers specifically to anhydrous ethanol or other alcohol solvents that can dissolve citric acid and the reaction products. Non-polar solvents that are incompatible with the system should be avoided.

[0038] Example 1

[0039] See Figure 1 and Figure 2 This embodiment provides a cutting method for LED epitaxial wafers. This method solves the problems of edge chipping and metal debris adhesion in existing multilayer composite wafers under high-speed cutting by constructing a protection system with stress buffering and active capture functions. The method includes the following detailed steps:

[0040] Step S1, Preparation of protective solution: (1) Preparation of component A: The raw materials of component A include: 40 parts by weight of methacrylic acid, 30 parts by weight of polyethylene glycol monomethacrylate (number average molecular weight Mn=500), 30 parts by weight of methacryloyloxyethyltrimethylammonium chloride, 0.25 parts by weight of water-soluble chain transfer agent mercaptoacetic acid, 0.8 parts by weight of initiator ammonium persulfate and 400 parts by weight of deionized water; the preparation method is set as follows: add 200 parts by weight of deionized water to the reaction vessel, and pass nitrogen gas to remove oxygen for 30 min. The temperature was raised to 75℃; a homogeneous monomer aqueous solution was prepared by mixing methacrylic acid, polyethylene glycol monomethacrylate (Mn=500), methacryloyloxyethyltrimethylammonium chloride, mercaptoacetic acid, and the remaining 200 parts by weight of deionized water; 0.8 parts by weight of ammonium persulfate was dissolved in 10 parts by weight of deionized water to prepare the initiating phase; the monomer phase and the initiating phase were added dropwise simultaneously using a double dropwise polymerization process for 1.5 h; after the dropwise addition was completed, the temperature was raised to 85℃, and the mixture was stirred at 300 r / min for 4 h to mature. After cooling, the pH was adjusted to neutral to obtain component A.

[0041] (2) Preparation of Component B: The raw materials for Component B include 19 parts by weight of citric acid, 7 parts by weight of ethylenediamine, and 100 parts by weight of anhydrous ethanol as a resolvent. The preparation method is as follows: citric acid is dissolved in 20 parts by weight of anhydrous ethanol, cooled to 3°C in an ice bath, and ethylenediamine is slowly added dropwise. The mixture is stirred and reacted for 30 min to form a salt. After removing the ethanol by rotary evaporation, the residue is transferred to a reaction vessel and heated to 150°C under nitrogen protection for melt polycondensation reaction for 3-5 h. During the reaction, the viscosity is indirectly controlled by monitoring the output torque of the stirring motor. Preliminary measurements show that when the torque increases by 25%-30% compared to the initial molten state, the corresponding viscosity reaches the target range. At this time, the melt polycondensation reaction time is about 4 h. When the viscosity is monitored to be equivalent to 150°C and a shear rate of 10 s, the viscosity is controlled to be ... -1 When the melt viscosity reaches 70 Pa·s, heating is immediately stopped, the cooling jacket of the reactor is opened and cold nitrogen gas is introduced into the reactor to cool the material to below 60°C within 10 minutes in order to control the degree of condensation and prevent cross-linking and gelation. The resulting reddish-brown solid prepolymer is redissolved in 100 parts by weight of anhydrous ethanol, and the insoluble matter is removed by filtration to obtain a B component solution with a solid content of about 20%.

[0042] (3) Mixing and blending: Weigh the above-prepared components A and B at a mass ratio of 10:1 and mix them. Add ammonia water as a volatile alkaline regulator to adjust the pH of the system to 8.5 for pH adjustment and viscosity stabilization. Add deionized water to dilute to a viscosity of 400 mPa·s. Then, perform ultrasonic defoaming treatment for 20 min to obtain a protective solution.

[0043] Step S2, Dynamic Coating: The protective liquid obtained in Step S1 is coated onto the surface of the LED epitaxial wafer using a gradient spin coating process to form a liquid film. The gradient spin coating process includes three stages: the first stage is set with a rotation speed of 500 r / min and a spin coating time of 5 s to allow the protective liquid to spread; the second stage is set with a rotation speed of 2500 r / min and an acceleration of 500 r / min / s and a spin coating time of 30 s to form the main film layer; the third stage is set with a rotation speed of 3000 r / min and a spin coating time of 5 s to remove edge adhesive beads.

[0044] Step S3, Temperature Curing: The liquid film is baked at a gradient temperature to allow the solvent and volatile components in the liquid film to escape and form a solid protective layer on the surface of the LED epitaxial wafer; specifically, the temperature is set to 60°C and baked for 60 seconds to remove the solvent and prevent boiling; then the temperature is set to 90°C and baked for 90 seconds to volatilize the alkaline regulator to lower the pH value and induce the formation of physical anchoring.

[0045] Step S4: Cutting: The LED epitaxial wafer covered with a solid protective layer is mechanically cut with a cutting wheel, and the cutting wheel speed is set to 35000 r / min;

[0046] Step S5, Phase Change Cleaning: The cut LED epitaxial wafer is rinsed with deionized water to dissociate the solid protective layer and remove the cutting debris. The rinsing pressure of the deionized water is set to 0.5 MPa. The high osmotic pressure environment of the deionized water and the strong hydrophilicity of the polyethylene glycol side chains induce the solid protective layer network to absorb water and swell rapidly. The expansion stress generated by the volume phase change overcomes the physical anchoring effect between the polymer and the wafer surface, thereby achieving complete removal.

[0047] Example 2

[0048] This embodiment is designed for conventional LED epitaxial wafer cutting scenarios with relatively flat surfaces and high production efficiency requirements, and the parameters have been adjusted based on Embodiment 1.

[0049] In step S1, the protective solution is prepared with a proportion that favors a rigid framework. The raw materials include: Parts by weight of methacrylic acid Parts by weight of polyethylene glycol monomethacrylate, Parts by weight of methacryloyloxyethyltrimethylammonium chloride Parts by weight of n-dodecyl mercaptan, Initiator by weight and Parts by weight of deionized water; in the preparation method of component A, the monomer phase is added dropwise to... Add chain transfer agent at the appropriate time, and control the reaction temperature at [temperature range]. Stir and cook ;

[0050] Component B selection: Citric acid by weight Parts by weight of ethylenediamine and Anhydrous ethanol in parts by weight; in the preparation method of component B, the melt polycondensation reaction temperature is set to 145℃, and the reaction time is... ;

[0051] The mixing and blending process is as follows: according to the mass ratio Weigh out components A and B, and add ammonia to adjust the pH to the specified values. Dilute to viscosity Ultrasonic defoaming ;

[0052] In step S2, dynamic coating, the gradient spin coating process parameters are set as follows: First stage Spin coating Phase Two acceleration Spin coating Phase Three Spin coating ;

[0053] In step S3, temperature-controlled curing, the temperature is set to... bake Subsequently bake ;

[0054] In step S4, during the cutting process, the rotational speed of the mechanical cutting wheel is set to... ;

[0055] In step S5, the phase change cleaning process, the rinsing pressure of the deionized water is set to... .

[0056] Example 3

[0057] This embodiment is for LED epitaxial wafers with a thicker metal electrode layer. Based on embodiment 1, it focuses on enhancing the ability to capture metal debris and the antistatic properties.

[0058] In step S1, the proportion of functional monomers in component A is increased, and the raw materials include: Parts by weight of methacrylic acid Parts by weight of polyethylene glycol monomethacrylate, Parts by weight of methacryloyloxyethyltrimethylammonium chloride Parts by weight of n-dodecyl mercaptan, Initiator by weight and Parts by weight of deionized water; in the preparation method of component A, the monomer phase is added dropwise to... Add chain transfer agent at the appropriate time, reaction temperature , ripening ;

[0059] Component B increases the concentration of the trapping agent; its raw materials include: Citric acid by weight Parts by weight of ethylenediamine and Anhydrous ethanol in parts by weight; in the preparation method of component B, the melt polycondensation reaction temperature is set to 150℃ and the reaction time is 4h;

[0060] The mixing and blending process is as follows: according to the mass ratio Weigh out components A and B, and add ammonia to adjust the pH to the specified values. Dilute to viscosity Ultrasonic defoaming ;

[0061] In step S2, dynamic coating, the gradient spin coating process parameters are set as follows: First stage Spin coating Phase Two acceleration Spin coating Phase Three Spin coating ;

[0062] In step S3, temperature-controlled curing, the temperature is set to... bake Subsequently bake ;

[0063] In step S4, during the cutting process, the rotational speed of the mechanical cutting wheel is set to... ;

[0064] In step S5, the phase change cleaning process, the rinsing pressure of the deionized water is set to... .

[0065] Example 4

[0066] This embodiment is specifically designed for surfaces with a step height greater than [missing information]. The problem of insufficient step coverage for complex-shaped LED epitaxial wafers is solved by introducing a static settling process, based on Example 1.

[0067] The proportions of raw materials and preparation methods for each component in step S1 are consistent with those in Example 1, and the mixing ratio is the same. pH adjusted to Viscosity controlled at ;

[0068] In step S2 dynamic coating, the gradient spin coating process is adjusted to: first stage Spin coating Phase Two Spin coating After the second stage, a settling process is added, with the settling time set as follows: This settling process utilizes solvent evaporation to induce thixotropy, allowing the protective liquid to rapidly establish yield stress at the step edge, resisting gravity flow; followed by the third stage. Spin coating ;

[0069] The parameters for steps S3 to S5 are the same as in Example 1: S3 Baking and S4 cutter wheel speed S5 flushing pressure .

[0070] Example 5

[0071] This embodiment explores the process adaptability of using laser stealth cutting to replace mechanical blade wheel cutting, and its basic process is the same as that in Embodiment 1;

[0072] In step S1, the raw material for component A in preparing the protective solution includes: Parts by weight of methacrylic acid Parts by weight of polyethylene glycol monomethacrylate, Parts by weight of methacryloyloxyethyltrimethylammonium chloride Parts by weight of n-dodecyl mercaptan, Initiator by weight and Parts by weight of deionized water; in the preparation method of component A, the dropping time is extended to... To ensure a more uniform molecular weight distribution; Component B raw materials include: Citric acid by weight Parts by weight of ethylenediamine and Anhydrous ethanol in parts by weight; the mixing and blending process is as follows: according to the mass ratio Mix, adjust pH to viscosity Ultrasonic defoaming ;

[0073] In step S2, dynamic coating, standard gradient spin coating is used: first stage Spin coating Phase Two acceleration Spin coating Phase Three Spin coating ;

[0074] In step S3, temperature-controlled curing, a two-stage baking process is employed: and ;

[0075] In step S4, laser stealth cutting is performed on the LED epitaxial wafer covered with a solid protective layer. The solid protective layer mainly serves to prevent the back adhesion of smoke and debris generated by laser ablation.

[0076] In step S5, the phase change cleaning process, the rinsing pressure of the deionized water is set to... .

[0077] Comparative Example

[0078] To further illustrate the beneficial effects of the technical solution of the present invention, the following comparative examples were used for performance testing:

[0079] Comparative Example 1

[0080] The only difference from Example 1 is that no chain transfer agent (n-dodecyl mercaptan) was added during the preparation of component A, and a one-time feeding polymerization was used instead of a double-dropping process; the remaining raw material ratios and process steps are exactly the same as in Example 1; this comparative example aims to verify the bimodal molecular weight distribution and the effect of the chain transfer agent on the rheological properties under high shear.

[0081] Comparative Example 2

[0082] The only difference from Example 1 is that: in the S1 mixing and blending process, no volatile alkaline regulator (ammonia) was added, and component A and component B were directly mixed and diluted for use; the other conditions were the same as in Example 1; this comparative example aims to verify the effect of pH adjustment and viscosity stabilization treatment on the pot life of the protective solution and cleaning residue.

[0083] Comparative Example 3

[0084] The coating is applied using a commercially available, standard water-soluble PVA protective solution, and then cured and cut according to its standard process. ) and cleaning.

[0085] To verify the structure and molecular weight distribution characteristics of the resin prepared in this invention, the structures of components A and B prepared in Example 1 were characterized:

[0086] Molecular weight distribution of component A: Gel permeation chromatography was used for testing. The results showed that component A exhibited a distinct bimodal distribution; the weight-average molecular weight distribution of the low molecular weight fraction was as follows: The region, primarily regulated by chain transfer agents, imparts excellent wettability and rheological responsiveness to the material; the weight-average molecular weight distribution of the high molecular weight fraction is within a certain range. The region, which forms the main framework of the solid protective layer, provides mechanical strength; the dual-mode distribution coefficient is 3.8, confirming that the specific chain transfer agent addition process successfully controlled the molecular weight distribution;

[0087] Infrared spectral analysis of component B: Infrared spectral scanning was performed on the prepared component B dry film; the spectrum at 1650 cm⁻¹... -1 A strong absorption peak appears at 1540 cm⁻¹, corresponding to the amide I band (C=O stretching vibration); at 1540 cm⁻¹... -1 An absorption peak appears at 1710 cm⁻¹, corresponding to the amide II band (NH bending vibration); at the same time, the characteristic peak of the carboxyl group at 1710 cm⁻¹ is retained; this indicates that citric acid and ethylenediamine successfully underwent partial amidation reaction during melt polycondensation, forming a hyperbranched polyamide structure with both amide bond backbone and active carboxyl groups on the side chain. This structure is the material basis for realizing the functions of metal chelation and water washing desorption.

[0088] Performance comparison and effect analysis

[0089] The diced wafers obtained in Examples 1-5 and Comparative Examples 1-3 were inspected. The inspection items included: chipping size (maximum chipping width observed under a microscope), electrode corrosion / oxidation (discoloration caused by residual metal debris), and the pot life of the protective solution (viscosity increase exceeding [percentage missing]). Time of cleaning and residual cleaning (SEM scan); data are summarized in the following table:

[0090] Table 1 Comparison of performance test results of each embodiment and comparative example.

[0091]

[0092] As shown in Table 1, Example 1, employing a dual-mode molecular weight distribution A component and pH latency technology, maintained an extremely low chipping size even under ultra-high-speed cutting, and the electrode surface remained bright and residue-free after cleaning. In contrast, Comparative Example 1, lacking chain transfer agent regulation, failed to form a dual-mode distribution, resulting in a shear thickening effect under high shear, losing its lubricating buffering effect, and causing a surge in chipping size. Comparative Example 2 lacked pH adjustment and viscosity stabilization treatment, resulting in premature hydrogen bonding complexation of components A and B after mixing, shortening the pot life to [missing information]. Within hours, and because the complex structure is difficult to dissociate during cleaning, residues are generated, resulting in slight oxidation of the electrode; the existing technology represented by Comparative Example 3 cannot cope with the high stress and heat generated by high-speed cutting, resulting in severe edge chipping and carbonization residue problems; the data of Example 4 proves the effectiveness of the static process in solving the problem of deep groove structure coverage.

[0093] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for cutting LED epitaxial wafers, characterized in that, Includes the following steps: S1. Preparation of Protective Solution: A component is an amphoteric acrylic resin copolymerized from methacrylic acid, polyethylene glycol monomethacrylate, and methacryloyloxyethyltrimethylammonium chloride; B component is a hyperbranched polyamide obtained by melt polycondensation of citric acid and ethylenediamine; Components A and B are weighed and mixed at a mass ratio of 9:1 to 11:1; a volatile alkaline regulator is then added to adjust the pH of the system to 8.3 to 8.7, followed by pH adjustment and viscosity stabilization treatment. The volatile alkaline regulator is ammonia or a water-soluble organic amine with a boiling point below 100℃; deionized water is then added to dilute the solution to a viscosity of 300 to 500 mPa·s, and the solution is then subjected to ultrasonic defoaming treatment to obtain the protective solution. S2, Dynamic Coating: The protective liquid obtained in step S1 is coated onto the surface of the LED epitaxial wafer through a gradient spin coating process to form a liquid film; S3, Temperature-dependent curing: The liquid film is baked with a gradient temperature increase, which causes the solvent and volatile components in the liquid film to escape and form a solid protective layer on the surface of the LED epitaxial wafer. S4. Cutting: Perform mechanical wheel cutting or laser stealth cutting on the LED epitaxial wafer covered with a solid protective layer. S5. Phase change cleaning: Use deionized water to rinse the cut LED epitaxial wafer. The rinsing pressure is set to 0.4~0.6MPa. The deionized water environment induces the polymer chain segments to absorb water and swell at a high rate, which destroys the dense structure of the solidified film layer, thereby causing the solid protective layer to quickly disintegrate and completely remove the cutting debris and molten metal from the wafer surface. Component A comprises the following raw materials in parts by weight: 35-45 parts methacrylic acid, 25-35 parts polyethylene glycol monomethacrylate with a number average molecular weight of 400-600, 25-35 parts methacryloyloxyethyltrimethylammonium chloride, 0.2-0.6 parts chain transfer agent, 0.6-1.0 parts initiator, and 380-420 parts deionized water; Component B comprises the following raw materials in parts by weight: 18-20 parts citric acid, 6-8 parts ethylenediamine and 90-110 parts solvent; The preparation method of component A is as follows: Add some deionized water to a reaction vessel, purge with inert gas for 20-40 minutes to remove oxygen, and heat to 70-80℃; mix methacrylic acid, polyethylene glycol monomethacrylate, methacryloyloxyethyltrimethylammonium chloride, and the remaining deionized water to obtain the monomer phase; dissolve the initiator to obtain the initiating phase; simultaneously add the monomer phase and the initiating phase using a double-drop polymerization process, wherein the chain transfer agent is dissolved in the monomer phase and is added starting when the addition reaches 45-55% of the monomer phase, and the addition process lasts for 1-2 hours; after the addition is complete, heat to 80-90℃, set to 250-350 r / min for stirring and maturation for 3-5 hours, cool down, and adjust the pH to neutral to obtain component A; the chain transfer agent is thioglycolic acid, and the amount is adjusted to 0.2-0.6 parts by weight; The preparation method of component B is as follows: citric acid is dissolved in anhydrous ethanol solvent and cooled to 0-5°C in an ice bath environment. Ethylenediamine is slowly added dropwise, controlling the dropping rate to prevent violent exothermic reaction. The reaction is stirred for 30-60 min to form an ammonium salt intermediate. The intermediate is then transferred to a rotary evaporator to completely remove the solvent under reduced pressure, yielding a solid ammonium salt intermediate. The solid ammonium salt intermediate is placed in a reaction vessel and heated to 145-155°C under nitrogen protection for melt polycondensation reaction for 3-5 h. During the reaction, the viscosity of the system is monitored using an online viscometer or stirring power monitor. When the viscosity is detected at a shear rate of 10 s⁻¹, the viscosity is measured. -1 When the melt viscosity reaches 60-80 Pa·s under the given conditions, heating should be stopped immediately and the temperature should be rapidly reduced to room temperature to prevent cross-linking and gelation of the system. The resulting product should be placed in anhydrous ethanol and stirred and refluxed in a water bath at 40-50°C, along with ultrasonic dispersion, until completely dissolved. The solid content should be adjusted to 40%-50% to obtain an alcohol-soluble component B solution.

2. The method for cutting LED epitaxial wafers according to claim 1, characterized in that, Ammonia is selected as the volatile alkaline regulator.

3. The method for cutting LED epitaxial wafers according to claim 1, characterized in that, In S2, the gradient spin coating process includes three stages: First stage: Set the rotation speed to 400~600r / min, spin coat for 4~6s to allow the protective liquid to spread; Second stage: Set the rotation speed to 2400~2600 r / min, the acceleration to 400~600 r / min / s, spin coat for 25~35s to form the main film layer; Third stage: Set the rotation speed to 2800~3200r / min, spin coat for 4~6s, and remove the glue beads at the edges; For LED epitaxial wafers with a surface step height greater than 5μm, after the second stage, a settling process is added for 8~12s. After the thixotropy is established by solvent evaporation, the third stage is then carried out.

4. The method for cutting LED epitaxial wafers according to claim 1, characterized in that, In S3, gradient heating baking includes: S31. Set the temperature to 55~65℃ and bake for 50~70 seconds to remove solvent and prevent boiling over. S32. Set the temperature to 85~95℃ and bake for 80~100s to volatilize the alkaline regulator to lower the pH value and induce physical anchoring formation.

5. The method for cutting LED epitaxial wafers according to claim 1, characterized in that, In S4, the rotational speed of the mechanical cutting wheel is set to be greater than 30,000 r / min; In S5, the rinsing pressure of deionized water is set to 0.4~0.6MPa, utilizing the pH neutral water environment to dissociate the hydrogen bonds between carboxyl and amino groups.

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