Method and device for detecting defects of epitaxial wafer of light emitting diode

Abstract

The invention relates to the technical field of defect detection, and discloses a method and a device for detecting defects of an epitaxial wafer of a light-emitting diode. The method comprises the following steps: S1, putting an epitaxial wafer into a feeding pipe, starting a driving device to drive a pushing mechanism, and pushing the epitaxial wafer to a detection position by adjusting the driving device; s2, driving a transmission gear system to be engaged through a transmission assembly, driving an intermittent transmission mechanism to be intermittently engaged with a driven gear, and enabling a lifting driving mechanism to rotate to drive a detection block to be in spring loading descending contact with the epitaxial wafer; s3, measuring the height of the bottom surface of the detection block and calculating the thickness of the epitaxial wafer; and S4, determining a defect detection result based on the thickness of the epitaxial wafer and the standard thickness, and controlling a sorting execution mechanism to perform partitioned storage according to the defect detection result. According to the invention, the start-stop impact vibration is inhibited, the pushing position error is reduced, and the in-place precision of the epitaxial wafer is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of defect detection, in particular to a method and device for detecting defects of an epitaxial wafer of a light emitting diode. BACKGROUND

[0002] The thickness uniformity of an epitaxial wafer of a light emitting diode directly affects the consistency of the light emitting wavelength and the light efficiency of the device as the core substrate for LED manufacturing. The conventional epitaxial wafer thickness detection device uses fixed speed control in the process of pushing the wafer one by one, and the start-stop impact can cause large pushing position error, affecting the alignment accuracy of the detection block and the epitaxial wafer. Meanwhile, in the process of contact thickness measurement, the dynamic vibration and spring nonlinearity caused by the extrusion of the detection block on the epitaxial wafer can introduce measurement error, reducing the repeatability accuracy of the thickness measurement. SUMMARY

[0003] The main purpose of the present application is to provide a method and device for detecting defects of an epitaxial wafer of a light emitting diode. The present application suppresses the start-stop impact vibration, reduces the pushing position error, improves the alignment accuracy of the epitaxial wafer, introduces the spring compression amount bias compensation coefficient to correct the measurement results, compensates for the error caused by the contact deformation of the epitaxial wafer and the nonlinearity of the elastic element, improves the repeatability accuracy and accuracy of the thickness measurement, and realizes high efficiency and high precision defect detection of the LED epitaxial wafer one by one.

[0004] To achieve the above purpose, the present application provides a method for detecting defects of an epitaxial wafer of a light emitting diode, comprising the following steps: S1: put the epitaxial wafer into the feeding pipe and start the driving device to drive the pushing mechanism, and push the epitaxial wafer to the detection position by adjusting the driving device; S2: drive the intermittent transmission mechanism to intermittently engage with the driven gear by driving the transmission assembly to engage with the transmission gear system, so that the lifting driving mechanism rotates to drive the detection block spring to load and descend to contact the epitaxial wafer; S3: measure the height of the bottom surface of the detection block and calculate the thickness of the epitaxial wafer; S4: determine the defect detection result based on the thickness of the epitaxial wafer and the standard thickness, and control the sorting execution mechanism to store in different zones according to the defect detection result.

[0005] Optionally, in the first implementation manner of the first aspect of the present application, step S1 comprises: S11: put the epitaxial wafer into the feeding pipe and slide to the pushing waiting position, and start the driving device to drive the reciprocating linear pushing motion of the pushing mechanism; S12: set the initial displacement and initial speed of the pushing mechanism based on the speed difference between the target speed and the initial speed; S13: constructing a sliding mode switching function based on the speed difference and an integral term of the speed difference, setting a switching gain coefficient of the sliding mode switching function, setting a control gain and an adaptive gain coefficient according to an absolute value of the sliding mode switching function; S14: collecting a pushing displacement and a pushing speed of the pushing mechanism and adjusting an output torque of the driving device to control the pushing speed, and pushing the epitaxial wafer to the detection position.

[0006] Optionally, in the second implementation manner of the first aspect of the present application, the step S13 comprises: S131: time-integrating the speed difference to obtain an integral term and set a switching gain coefficient of the sliding mode switching function, and constructing the sliding mode switching function based on the speed difference, the switching gain coefficient and the integral term; S132: setting a control gain and setting a corresponding adaptive gain coefficient according to a chattering requirement of the sliding mode switching function.

[0007] Optionally, in the third implementation manner of the first aspect of the present application, the step S14 comprises: S141: the displacement measuring device measures the pushing displacement of the pushing mechanism and calculates the pushing speed, and updates the sliding mode switching function based on a target speed and the pushing speed; S142: judging a sign of the sliding mode switching function, calculating an output torque adjustment amount of the driving device based on the control gain and the sign of the sliding mode switching function, and transmitting the output torque adjustment amount to the screw driving mechanism through the gear transmission system to drive the pushing mechanism to adjust the pushing speed; S143: controlling the pushing mechanism to push the epitaxial wafer, and stopping the pushing when the pushing displacement reaches a target pushing distance to obtain the epitaxial wafer at the detection position.

[0008] Optionally, in the fourth implementation manner of the first aspect of the present application, the step S142 comprises: S1421: judging the sign of the sliding mode switching function, outputting a deceleration instruction when the sign is positive, outputting an acceleration instruction when the sign is negative, multiplying the control gain and the sign of the sliding mode switching function to obtain the output torque adjustment amount of the driving device; S1422: transmitting the output torque adjustment amount of the driving device to the intermediate transmission shaft through the main transmission shaft to drive the gear transmission system; S1423: the intermediate transmission shaft drives the screw transmission shaft to rotate through the spur gear transmission mechanism to drive the screw driving mechanism to rotate, the screw driving mechanism drives the moving base and the transmission assembly to move through the nut pair, and the transmission assembly controls the pushing speed of the pushing mechanism through the transmission conversion mechanism.

[0009] Optionally, in the fifth implementation manner of the first aspect of the present application, the step S2 comprises: S21: the transmission assembly rotates to drive the driving bevel gear in the transmission gear system to engage the driven bevel gear, the driven bevel gear drives the first transmission shaft to rotate, the intermittent transmission mechanism outside the first transmission shaft intermittently engages the driven gear in the effective transmission area, and the second transmission shaft is driven to rotate to drive the lifting driving mechanism to rotate; S22: the lifting driving mechanism drives the lifting seat to descend along the guide mechanism through the nut pair, the support assembly fixed to the lifting seat drives the adjusting rod and the telescopic rod to descend, and the detection block at the bottom end of the telescopic rod contacts the surface of the epitaxial wafer under the pre-tightening force of the elastic element.

[0010] Optionally, in a sixth implementation form of the first aspect of the present application, step S3 comprises: S31: when the detection block remains in the extrusion state, the displacement measuring device measures the height of the bottom surface of the detection block at a first sampling time to obtain a first measured height, measures the height at a second sampling time after a set interval to obtain a second measured height, and measures the height at a third sampling time after another set interval to obtain a third measured height; S32: the first measured height, the second measured height and the third measured height are added and then divided by three to obtain an average height value, a height difference between the average height value and a height reference value of the detection block is calculated, a difference between a target compression amount of the elastic element and a distance and the height difference of the lifting driving mechanism is calculated to obtain a compression amount deviation of the elastic element, the compression amount deviation of the elastic element is multiplied by a spring compression amount deviation compensation coefficient to obtain a compensation amount, and a standard epitaxial wafer thickness is added to the difference and the compensation amount to obtain the epitaxial wafer thickness.

[0011] Optionally, in a seventh implementation form of the first aspect of the present application, step S4 comprises: S41: a thickness difference value is obtained by subtracting the epitaxial wafer thickness from the standard epitaxial wafer thickness; S42: a relationship between the thickness difference value and a thickness difference value threshold is judged, the defect detection result is marked as an over-thick defect when the thickness difference value is greater than the thickness difference value threshold, the defect detection result is marked as an over-thin defect when the thickness difference value is less than a negative value of the thickness difference value threshold, and the defect detection result is marked as qualified when an absolute value of the thickness difference value is less than or equal to the thickness difference value threshold; S43: the intermittent transmission mechanism reversely engages to drive the detection block to ascend and separate from the epitaxial wafer, the pushing mechanism pushes the epitaxial wafer to the collecting device, and the sorting execution mechanism is controlled according to the defect detection result to store in different zones.

[0012] Optionally, in an eighth implementation form of the first aspect of the present application, step S43 comprises: S431: the intermittent transmission mechanism reversely engages the driven gear after rotating through the non-transmission area, drives the lifting driving mechanism to reversely rotate, and drives the detection block to ascend along the guide mechanism and separate from the surface of the epitaxial wafer through the lifting seat and the support assembly; S432: The pushing mechanism pushes the epitaxial wafer to the opening of the isolation plate again and falls into the collection device, and according to the defect detection result, the sorting execution mechanism is driven to move, so that the qualified epitaxial wafer, the too thick defect epitaxial wafer and the too thin defect epitaxial wafer are respectively stored in different partitions of the collection device.

[0013] The application further provides an epitaxial wafer defect detection device of a light emitting diode, which is used for executing the steps of the epitaxial wafer defect detection method of the light emitting diode.

[0014] To sum up, the application sets a sliding mode controller to adjust the feeding speed of the pushing mechanism in real time, constructs a sliding mode switching function based on the speed deviation and its integral term, dynamically adjusts the output torque of the driving device according to the symbol of the switching function, realizes the accurate pushing of the epitaxial wafer by the pushing mechanism according to the three-stage speed planning of the acceleration section, the uniform speed section and the deceleration section, suppresses the start-stop impact vibration, reduces the pushing position error, improves the epitaxial wafer positioning accuracy, sets the intermittent transmission mechanism and the driven gear to intermittently mesh in the effective transmission area, drives the detection block to spring-loaded contact the surface of the epitaxial wafer under the pre-tightening force of the elastic element, realizes the accurate timing coordination of the pushing and detection actions, and avoids the interference problem under the continuous transmission mode. The displacement measuring device samples the height of the bottom surface of the detection block three times and takes the arithmetic mean value, effectively eliminates the random measurement noise, calculates the compression amount deviation of the elastic element based on the difference between the target compression amount of the elastic element and the height difference between the actual descending distance and the height of the lifting driving mechanism, introduces the spring compression amount deviation compensation coefficient to modify the measurement result, compensates the error caused by the epitaxial wafer contact deformation and the nonlinear characteristics of the elastic element, improves the repeatability accuracy and accuracy of the thickness measurement, and realizes the high-efficiency and high-precision piece-by-piece defect detection of the LED epitaxial wafer. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the steps of the epitaxial wafer defect detection method of the light emitting diode in an embodiment of the application; Figure 2 is a comparison diagram of the pushing speed adjustment curves based on the sliding mode control in an embodiment of the application; Figure 3 is a L-shaped block intermittent pushing displacement-time characteristic and epitaxial wafer piece-by-piece detection beat diagram in an embodiment of the application.

[0016] The implementation, functional features and advantages of the application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0018] Referring Figure 1 The embodiment provides a method for detecting defects of an epitaxial wafer of a light emitting diode, comprising the following steps: S1: putting the epitaxial wafer into a feeding pipe and starting a driving device to drive a pushing mechanism, and pushing the epitaxial wafer to a detection position by adjusting the driving device; S2: driving a transmission gear system to engage through a transmission assembly, driving an intermittent transmission mechanism to intermittently engage with a driven gear, and rotating a lifting driving mechanism to drive a detection block to be spring-loaded and lowered to contact the epitaxial wafer; S3: measuring the height of the bottom surface of the detection block and calculating the thickness of the epitaxial wafer; S4: determining a defect detection result based on the thickness of the epitaxial wafer and a standard thickness, and controlling a sorting execution mechanism to store in different zones according to the defect detection result.

[0019] In one example, step S1 comprises: S11: putting the epitaxial wafer into the feeding pipe and sliding to a pushing waiting position, and starting a driving device to drive a pushing mechanism to perform a reciprocating linear pushing motion; S12: setting an initial displacement and an initial speed of the pushing mechanism, and calculating a speed difference value based on a target speed and the initial speed; S13: constructing a sliding mode switching function based on the speed difference value and an integral term thereof, setting a switching gain coefficient of the sliding mode switching function, and setting a control gain and an adaptive gain coefficient according to the absolute value of the sliding mode switching function; S14: collecting the pushing displacement and the pushing speed of the pushing mechanism and adjusting the output torque of the driving device to control the pushing speed, and pushing the epitaxial wafer to the detection position.

[0020] In this example, the epitaxial wafers to be tested are sequentially put into the inlet of the feeding pipe and slide along the wall of the feeding pipe to the pushing waiting position at the lower end under the action of gravity. The pushing waiting position is located in front of the L-shaped pushing mechanism and is aligned with the initial pushing displacement position. After the pushing preparation is completed, the motor driving device is started to make the L-shaped block in the pushing mechanism start a periodic reciprocating linear motion in the horizontal direction. The pushing structure is connected with the guide bearing assembly through a screw-nut pair and maintains the linear stability of the trajectory in a high-frequency switching state. The control system sets the initial displacement x(0)=0mm and the initial speed v(0)=0mm / s of the L-shaped block, configures the target pushing distance x tar (such as 25mm) and the target speed v t (such as 45mm / s), calculates the difference value e(t)=v(t)-v t, the speed difference value is taken as a pushing state error signal. The speed difference value is introduced into the core function construction process of the sliding mode controller, and a sliding mode switching function is established according to the control law σ(t)=e(t)+λ∫e(τ)dτ, wherein λ is a switching gain coefficient, and the value is set by identification and engineering optimization to balance response speed and chattering suppression. The absolute value of σ(t) is taken as a dynamic adjustment factor to set the control gain K0 and the adaptive gain K a , so that the total control gain K(t)=K0+K a ·|σ(t)| is able to adaptively adjust the control force amplitude according to the error state. In the pushing process, the displacement x(t) and the speed v(t) of the pushing mechanism are sampled at a high frequency, the speed deviation e(t) and the sliding mode switching function σ(t) are updated in real time in each sampling period, and the driving torque adjustment amount ΔT(t)= K(t)·sgn[σ(t)] is calculated according to the sign of σ(t) and the value of K(t), and the torque signal is fed back to the driving motor, so as to realize dynamic adjustment of the motor output response, and the adjustment result is transmitted to the L-shaped block through the multi-stage gear set and the screw system, forming a closed-loop control of the pushing speed. The closed-loop control mechanism enables the pushing mechanism to quickly respond to the control command in the entire motion cycle, and keeps the speed error |e(t)| stable within ±1.2mm / s in the multi-section speed trajectory (acceleration section, constant speed section, deceleration section), so that the epitaxial wafer pushing position error is controlled within the limit deviation of ±0.15mm, and the epitaxial wafer is smoothly and accurately pushed to the detection position.

[0021] In one example, step S13 comprises: S131: time-integrating the speed difference value to obtain an integral term and set a switching gain coefficient of the sliding mode switching function, and constructing the sliding mode switching function based on the speed difference value, the switching gain coefficient and the integral term; S132: setting a control gain, and setting a corresponding adaptive gain coefficient according to the chattering requirement of the sliding mode switching function.

[0022] Figure 2For the push speed adjustment curve based on sliding mode control, the horizontal axis is time (0~2.0s), and the vertical axis is push speed (0~50mm / s). In the figure, the solid line is the target speed curve, which adopts a three-stage speed planning: the acceleration stage (about 0.5s) accelerates from 0 to the maximum speed of 45mm / s, the constant speed stage (about 0.5~1.0s) maintains the constant speed of 45mm / s, and the deceleration stage (after 1.0s) decelerates from the maximum speed to 0. The dashed line is the actual speed curve of PID control, which has obvious overshoot and speed oscillation. At the end of the acceleration stage, the speed exceeds the target value by about 5mm / s, and fluctuations also occur in the constant speed stage and the deceleration stage. In contrast, the sliding mode control can achieve fast response, accurate tracking of the target speed curve, suppression of overshoot and oscillation, and control of the speed tracking error within ±1.2mm / s, which is better than the ±4.5mm / s error of traditional PID control, ensuring smooth and accurate positioning of the wafer during the wafer pushing process.

[0023] In this example, when the pushing mechanism starts to act, the control system collects the current speed v(t) of the L-shaped block in real time, and compares it with the target speed v t to obtain the speed error e(t)=v(t) v t The speed difference is integrated in time to obtain the integral term I(t)=∫0 t e(τ)dτ, which reflects the cumulative deviation of the pushing system in the entire time domain. In actual discrete control, the integral term is discretized by trapezoidal integration, i.e. I(t)=I(t Δt)+[e(t)+e(t Δt)]·Δt / 2, which ensures the numerical stability of the integration process within a finite sampling period. Based on the speed difference e(t), the integral term I(t), and the empirically set switching gain coefficient λ, the sliding mode switching function σ(t)=e(t)+λ·I(t) is constructed. The sliding mode switching function serves as an aggregated indicator of the current dynamic state, and its sign and amplitude jointly determine the direction and intensity of the controller output. The gain of the control output is differentiated and set, and a basic control gain K0 is set, which is used to maintain stable control ability when the error is small. When the error is large or the disturbance is severe, an adaptive gain K a is introduced, which is related to the amplitude of the switching function σ(t), so that the total control gain K(t)=K0+K a ·|σ(t)| can dynamically expand with the state, where the value of K a is determined according to the allowable range of chattering in sliding mode control. Through engineering parameter tuning or model simulation, its optimal interval is obtained, which ensures rapid convergence of the error while suppressing high-frequency oscillation, and realizes high-precision and high-robustness continuous control of the push speed of the L-shaped pushing mechanism.

[0024] In one example, step S14 comprises: S141: The displacement measuring device measures the pushing displacement of the pushing mechanism and calculates the pushing speed, and updates the sliding mode switching function based on the target speed and the pushing speed; S142: Determine the sign of the sliding mode switching function, calculate the drive device output torque adjustment amount based on the control gain and the sign of the sliding mode switching function, and transmit it to the screw drive mechanism through the gear transmission system to drive the pushing mechanism to adjust the pushing speed; S143: Control the pushing mechanism to push the epitaxial wafer, and stop pushing when the pushing displacement reaches the target pushing distance to obtain the epitaxial wafer at the detection position.

[0025] Figure 3 The L-shaped block intermittent pushing displacement-time characteristic and the epitaxial wafer piece-by-piece detection beat chart are shown in the figure. The horizontal axis is time (018s), and the vertical axis is the cumulative pushing displacement of the L-shaped block (0125mm). The curve rises in steps, and each step corresponds to the complete detection period of an epitaxial wafer. Starting from the pushing waiting position, the first epitaxial wafer is pushed 25mm to the detection position (corresponding to the first step), and after detection is completed, it is continuously pushed to the discharge position, and then the second, third, fourth, and fifth epitaxial wafers are pushed in turn. The pushing distance of each wafer is 25mm. Each detection period includes: pushing stage (L-shaped block accelerating-uniform decelerating pushing epitaxial wafer, about 0.85s), static detection stage (L-shaped block remains static, detects block spring-loaded thickness, about 0.8s), discharge stage (pushes epitaxial wafer to collection frame, about 0.45s). The horizontal section of the step curve represents the static detection time, and the vertical section represents the pushing motion time. The working characteristics of the L-shaped block intermittent pushing of the present application realize efficient detection of epitaxial wafers piece by piece, and the single wafer detection period is about 2.1s, improving the detection efficiency.

[0026] In this example, the displacement measuring device, such as a grating ruler or an encoder, is configured on the pushing mechanism stroke path to measure the actual displacement of the pushing mechanism in real time, and based on the displacement difference between two consecutive sampling time points divided by the sampling period Δt, the current pushing speed v(t)=[x(t) x(t Δt)] / Δt is calculated; at the same time, the current speed v(t) and the target speed v t of the control system are subjected to difference operation to obtain the speed error e(t)=v(t) v tand combines the switching gain coefficient λ and the historical integral term I(t), the sliding mode switching function σ(t)=e(t)+λ·I(t) is updated in real time to dynamically reflect the current speed deviation state. According to the sign of σ(t), the control command direction is determined. If σ(t)>0, it indicates that the current speed is higher than the target value, and a negative torque needs to be output to realize braking. If σ(t)<0, it indicates that the speed is insufficient, and a positive torque needs to be output to accelerate the correction. Accordingly, the preset basic control gain K0 and the adaptive gain K a The real-time control gain K(t)=K0+K a ·|σ(t)| is calculated, and the torque adjustment amount ΔT(t)= K(t)·sgn[σ(t)] of the driving device is output. The torque signal acts on the driving motor and transmits the rotation speed and direction through the multi-stage bevel gear set in the gear transmission system, and then converts the rotary motion into linear displacement through the screw-nut pair, thereby driving the pushing mechanism (such as an L-shaped block) to adjust the pushing speed. As the pushing mechanism approaches the target speed trajectory under continuous adjustment, the epitaxial wafer is gradually pushed forward, and when the displacement measuring device detects that the current pushing displacement x(t) has reached the preset target pushing distance x tar , for example, 25 mm, the control system immediately sends a stop command to the driving motor to cut off the torque output, and the pushing mechanism stops at the specified position, and the epitaxial wafer successfully reaches the detection position.

[0027] In this embodiment, after step S143, there is also a pushing to position accuracy verification and secondary adjustment step based on the convergence state of the sliding mode switching function: S144: After the pushing mechanism stops pushing, the sliding mode switching function value is continuously monitored, and the root mean square value of the sliding mode switching function within a set time window after stopping is calculated; S145: The relationship between the root mean square value of the sliding mode switching function and the convergence threshold is judged, and when the root mean square value is greater than the convergence threshold, it is determined that the pushing position has not converged stably, and the residual displacement deviation of the current pushing displacement and the target pushing distance is recorded; S146: The deviation direction is judged based on the sign of the residual displacement deviation, and when the residual displacement deviation is positive, the pushing mechanism is driven to retreat in the reverse direction, and when the residual displacement deviation is negative, the pushing mechanism is driven to advance in the forward direction, and the fine adjustment distance is the absolute value of the residual displacement deviation; S147: After fine adjustment, the root mean square value of the sliding mode switching function is monitored again, and when the root mean square value is less than or equal to the convergence threshold, it is confirmed that the epitaxial wafer reaches the accurate detection position, and the lifting driving mechanism is triggered to descend; S148: The initial speed deviation, the peak value of the sliding mode switching function, and the convergence time of this pushing process are recorded, and the average convergence time is calculated based on the pushing data of multiple epitaxial wafers in succession, and when the convergence time of a certain epitaxial wafer exceeds the average convergence time by a set multiple, the adaptive gain coefficient of the next epitaxial wafer pushing process is adaptively increased to speed up the convergence speed of the sliding mode switching function.

[0028] In one example, step S142 includes: S1421: judge the sign of the sliding mode switching function, output deceleration instruction when the sign is positive, output acceleration instruction when the sign is negative, multiply the control gain with the sign of the sliding mode switching function to get the driving device output torque adjustment amount, and take the negative value; S1422: transmit the driving device output torque adjustment amount to the intermediate transmission shaft through the gear transmission system driven by the main transmission shaft; S1423: the intermediate transmission shaft drives the screw transmission shaft through the spur gear transmission mechanism to rotate the screw drive mechanism, the screw drive mechanism drives the moving seat and the transmission assembly to move through the nut pair, and the transmission assembly controls the pushing speed of the pushing mechanism through the transmission conversion mechanism.

[0029] In this example, the control system judges the sign state of the sliding mode switching function σ(t) in real time, when σ(t) is positive, it indicates that the current speed of the pushing mechanism is higher than the target speed, and a deceleration control instruction needs to be output to reduce the driving torque; when σ(t) is negative, it indicates that the pushing speed is lower than the target speed, and an acceleration instruction needs to be issued to increase the driving force. Based on the judgment logic, according to the preset basic control gain K0 and the adaptive gain K a Calculate the current control gain K(t)=K0+K a ·|σ(t)|, and multiply the gain value with sgn[σ(t)] and take the negative value to generate the output torque adjustment amount ΔT(t)= K(t)·sgn[σ(t)], to realize the dynamic matching of the driving response of the current error state. The torque adjustment amount is directly acted on the main transmission shaft by the driving motor, the input gear installed on the main transmission shaft rotates under the action of the torque, and the rotating torque is transmitted to the intermediate transmission shaft through a set of bevel gears or helical gears in meshing, so that the intermediate transmission shaft obtains stable and continuous power input. The intermediate transmission shaft is in parallel engagement with the screw transmission shaft through the spur gear set fixedly connected thereto, drives the screw transmission shaft to rotate, and then converts the rotary motion into linear straight line motion through the screw-nut pair structure, and drives the moving seat arranged on the nut pair to move stably along the guide rail. The moving seat is rigidly connected with the transmission assembly, and the transmission assembly is connected with the pushing mechanism through the transmission conversion mechanism (such as a guide slider or a sliding coupling), so as to transmit and convert the linear displacement of the moving seat into the straight line pushing speed adjustment of the L-shaped block of the pushing mechanism, and realize the dynamic control of the speed of the L-shaped block in the acceleration and deceleration stages.

[0030] In one example, step S2 includes: S21: the transmission assembly rotates to drive the driving bevel gear in the transmission gear system to mesh with the driven bevel gear, the driven bevel gear drives the first transmission shaft to rotate, the intermittent transmission mechanism outside the first transmission shaft intermittently meshes with the driven gear in the effective transmission area, and drives the second transmission shaft to rotate to drive the lifting drive mechanism to rotate; S22: the lifting driving mechanism drives the lifting seat to descend along the guide mechanism through the nut pair, and the support assembly fixed to the lifting seat drives the adjusting rod and the telescopic rod to descend, and the detection block at the bottom end of the telescopic rod contacts the surface of the epitaxial wafer under the pre-tightening force of the elastic element.

[0031] In this example, when the epitaxial wafer is pushed to the detection position and stably stays, the control system starts the transmission assembly to rotate continuously at a set angular velocity, the output shaft of the transmission assembly is connected with the driving bevel gear, the driving bevel gear and the driven bevel gear form a stable meshing pair, transmit torque and realize transmission direction conversion, so that the driven bevel gear drives the first transmission shaft to rotate. The first transmission shaft is externally provided with an intermittent transmission mechanism, which is in the form of an incomplete gear, and only a certain sector area on the circumference is provided with a limited number of teeth, and the remaining circular arc is a toothless idling area, so as to realize intermittent power output. When the toothed segment of the incomplete gear on the first transmission shaft is meshed with the driven gear on the second transmission shaft, effective power transmission is generated, at this time the second transmission shaft obtains the rotating torque in the meshing segment time window and starts to rotate, thereby driving the lifting driving mechanism fixedly connected at the end of the second transmission shaft to rotate, and the rotation is only carried out during the intermittent meshing, and a downward driving action is completed. Under the rotating action of the lifting driving mechanism, the screw rod provided at the output end of the lifting driving mechanism starts to rotate, and the rotating motion is converted into linear displacement along the axial direction through the nut pair structure matched with the screw rod, drives the lifting seat fixedly connected with the nut pair to uniformly descend along the preset guide mechanism (such as a limiting rod or a precise slide rail), and keeps the stability of the movement direction and posture. The lifting seat is provided with a support assembly for mechanical transmission at the bottom, the support assembly is fixedly connected with the adjusting rod and indirectly connected with the telescopic rod, and the telescopic rod structure is provided with a compressible elastic element, such as a spiral compression spring, the upper end of the telescopic rod is sleeved with the adjusting rod and keeps an initial pre-compression state; when the lifting seat continuously descends, the adjusting rod and the telescopic rod synchronously descend as a whole, until the detection block fixed at the bottom end of the telescopic rod slowly contacts the surface of the epitaxial wafer in a static state, at this time the pre-tightening force of the elastic element applies a stable but controlled loading pressure to the detection block, so that the detection block realizes flexible contact instead of rigid collision, thereby avoiding damage to the epitaxial wafer while establishing a mechanical contact reference for thickness detection.

[0032] In this embodiment, after step S22, a step of identifying the contact time based on the acceleration mutation of the detection block and self-adapting the pre-tightening force of the elastic element is further included: S23: During the driving of the lifting driving mechanism in the lowering process of the detection block, the acceleration sensor collects the acceleration of the detection block in real time at a set sampling frequency, and the acceleration change rate is obtained by calculating the acceleration difference at adjacent two sampling times; S24: judging the relationship between the absolute value of the acceleration change rate and the contact recognition threshold value, when the absolute value of the acceleration change rate is greater than the contact recognition threshold value, it is determined that the detection block contacts the surface of the epitaxial wafer, and the height of the bottom surface of the detection block at the contact time is recorded as the initial contact height; S25: calculating the contact position deviation between the initial contact height and the preset contact height, when the absolute value of the contact position deviation is greater than the position deviation threshold value, it is determined that there is obvious convex or concave on the surface of the epitaxial wafer, and the epitaxial wafer is marked as surface topography abnormal; S26: calculating the equivalent contact stiffness of the surface of the epitaxial wafer based on the amplitude of the acceleration change rate at the contact time, and dividing the equivalent contact stiffness by the standard contact stiffness to obtain the stiffness ratio; S27: self-adapting the target compression amount of the elastic element according to the stiffness ratio, when the stiffness ratio is greater than the set upper limit value, increasing the target compression amount of the elastic element to compensate for the insufficient contact deformation of the hard surface of the epitaxial wafer, when the stiffness ratio is less than the set lower limit value, reducing the target compression amount of the elastic element to avoid excessive extrusion of the soft surface of the epitaxial wafer; S28: the lifting driving mechanism continues to drive the detection block to lower to the position corresponding to the adjusted target compression amount of the elastic element and then stops, and after waiting for a set stable time, the height sampling action of the displacement measuring device is performed.

[0033] After step S22 and before step S3, the method further comprises a measurement stability determination step based on time delay analysis of the block contact vibration signal: S221: after the block contacts the surface of the wafer, the vibration sensor collects the block vibration signal, and the displacement signal of the pushing mechanism is recorded simultaneously, and the signal collection time is set to a set time period from the contact moment; S222: the power spectrum of the block vibration signal and the displacement signal of the pushing mechanism is calculated respectively, and the power cepstrum of each is obtained by taking the logarithm of the respective power spectrum and performing inverse transform, and the time delay value corresponding to the first peak position in the block vibration signal power cepstrum is identified, which represents the delay characteristic of the block contact vibration relative to the interference vibration of the pushing mechanism; S223: based on the time delay value, the influence degree of the interference component of the pushing mechanism in the block vibration signal is determined, when the time delay value is greater than a set time delay threshold, it is determined that the block vibration and the pushing mechanism vibration are relatively independent, and the measurement stability determination can be directly performed; when the time delay value is less than or equal to the time delay threshold, it is determined that the interference of the pushing mechanism is significant, and the periodic component with the same frequency as the displacement signal of the pushing mechanism in the block vibration signal needs to be suppressed; S224: the envelope of the amplitude of the block vibration signal is calculated, and the decay time required for the envelope amplitude to decay from the peak value to a set percentage of the peak value is calculated, when the decay time is less than a set stability time threshold, it is determined that the block has entered a stable extrusion state, and the displacement measurement device is allowed to perform height sampling; when the decay time is greater than or equal to the stability time threshold, the waiting time is prolonged, and the determination is performed again until the stability condition is met.

[0034] In one example, step S3 comprises: S31: when the block is in the extrusion state, the displacement measurement device measures the height of the bottom surface of the block at a first sampling time to obtain a first measured height, measures the height at a second sampling time after a set time interval to obtain a second measured height, and measures the height at a third sampling time after a set time interval to obtain a third measured height; S32: the first measured height, the second measured height and the third measured height are added and divided by three to obtain an average height value, the height difference between the average height value and the block height reference value is calculated, the difference between the target compression amount of the elastic element and the descent distance of the lifting driving mechanism and the height difference value is calculated to obtain the compression amount deviation of the elastic element, the compression amount deviation of the elastic element is multiplied by the spring compression amount deviation compensation coefficient to obtain a compensation amount, and the standard wafer thickness is added to the difference and the compensation amount to obtain the wafer thickness.

[0035] In this example, when the detection block completes the contact with the surface of the wafer and enters a stable extrusion state under the action of the elastic loading mechanism, the control system keeps the detection block stationary to maintain the force condition unchanged, at this time the displacement measuring device is started to sample the height of the bottom surface of the detection block at multiple time points to improve the measurement accuracy. The displacement measuring device is a high-precision grating ruler or a laser displacement sensor, which continuously records the height of the bottom surface of the detection block without disturbing the state of the detection block. At the first sampling time t1, the absolute height H1 of the bottom surface of the detection block is recorded by the displacement measuring device, after a set stable time interval Δt (for example, 0.2 seconds), the second sampling is performed to obtain the second measurement height H2, and after a third time interval Δt, the third sampling is performed to obtain the third measurement height H3, forming a three-point time sequence sample. In order to eliminate the accidental deviation caused by mechanical microseismicity, material hysteresis or environmental noise, the arithmetic average operation is performed on the above three height values, and the average measurement height =(H1+H2+H3) / 3 is obtained by adding H1, H2 and H3 and dividing by three. The average height value is compared with the preset detection block height reference value H0, and the height difference between them is calculated, which reflects the relative deviation of the detection block between the standard state and the current measurement state; at the same time, the total descent distance Δd corresponding to this descent is calculated according to the screw stroke parameter and the angle control data of the lifting driving mechanism, and then combined with the target compression amount δ tar of the elastic element (such as a spiral spring), the deviation value δ e of the actual compression amount of the elastic element relative to the theoretical compression is obtained by tar [Δd ΔH] = δ e , which reflects the error accumulation caused by the elastic compression of the wafer surface or the deformation amount of the detection block. The spring compression amount deviation compensation coefficient η determined by the calibration process is introduced, and multiplied by δ e to obtain the modified compensation amount η·δ e . The control system calculates the thickness value h of the current wafer according to the standard thickness value h0 of the wafer, and adds the height difference ΔH and the compensation amount η·δ e together to perform the calculation formula h=h0+ΔH+η·δ e .

[0036] In one example, step S4 includes: S41: subtracting the thickness of the wafer from the standard wafer thickness to obtain a thickness difference; S42: judging the relationship between the thickness difference value and the thickness difference value threshold, marking the defect detection result as over-thick defect when the thickness difference value is greater than the thickness difference value threshold, marking the defect detection result as over-thin defect when the thickness difference value is less than the negative value of the thickness difference value threshold, and marking the defect detection result as qualified when the absolute value of the thickness difference value is less than or equal to the thickness difference value threshold; S43: the intermittent transmission mechanism reversely engages the detection block to make the detection block rise and separate from the epitaxial wafer, the pushing mechanism pushes the epitaxial wafer to the collecting device, and the sorting execution mechanism is controlled according to the defect detection result to store in different zones.

[0037] In this example, the control system calculates the difference between the current epitaxial wafer thickness value h(i) measured by the detection block and the preset standard epitaxial wafer thickness h0, and obtains the thickness deviation Δh(i)=h(i) h0. The thickness difference value is used to measure the actual deviation of the current wafer under the process control target value. The thickness difference value threshold δ th (e.g. ±2.5μm) is called and compared with Δh(i). When Δh(i) is greater than δ th , it indicates that the current epitaxial wafer thickness exceeds the upper limit of the standard, which is an "over-thick defect", and the defect mark D(i) is assigned as 1 at this time. If Δh(i) is less than δ th , that is, the thickness is lower than the lower limit of the standard, it indicates that there is an "over-thin defect", and the mark D(i)=2 at this time. If the absolute value of Δh(i) is less than or equal to δ thIf the thickness is within the tolerance range, the product is considered as "qualified" and the value D(i) = 0 is assigned. After the thickness determination is completed, the intermittent transmission mechanism enters the reverse meshing state, the incomplete gear rotates again and re-engages with the third gear in the reverse tooth area, driving the lifting drive mechanism to rotate in the reverse direction, thereby reversing the second reciprocating lead screw, the screw rod drives the nut pair and the second bearing seat fixed thereon to ascend along the guide rail, and the detection block rigidly connected therewith synchronously rises back to disengage from the surface of the epitaxial wafer, while the elastic element releases the pre-pressing energy and cooperates with the acceleration of the back-up action. After the detection block completely rises back, the pushing mechanism is restarted, and the L-shaped block of the slide mode controller pushes the epitaxial wafer that has been detected to the discharge position from the detection position, and an opening structure is provided at the end of the pushing path to make the epitaxial wafer vertically fall into the collection device under the action of gravity. At this time, the control system controls the position of the pneumatic push plate in the sorting execution mechanism according to the defect mark D(i). When D(i) = 0, the push plate remains in the neutral position, and the epitaxial wafer vertically falls into the left qualified area; when D(i) = 1, the push plate shifts to the left by a certain distance, guiding the epitaxial wafer into the middle over-thick defect collection area; when D(i) = 2, the push plate shifts to the right by the same distance, making the epitaxial wafer enter the right over-thin defect collection area, and completing the spatial partitioning collection operation according to the defect type. After the sorting action is completed, the push plate automatically resets, the next epitaxial wafer in the feeding pipe slides into the pushing waiting position under the action of gravity, the system resets the initial displacement and speed parameters of the pushing mechanism, reinitializes the slide mode controller, and enters the next detection cycle, realizing the closed-loop operation process of piece-by-piece cycle detection, judgment and intelligent sorting.

[0038] In one example, step S43 comprises: S431: After the intermittent transmission mechanism rotates through the non-transmission area, the driven gear is reversely meshed, driving the lifting drive mechanism to rotate in the reverse direction, and the detection block is driven to rise back along the guide mechanism to disengage from the surface of the epitaxial wafer through the lifting seat and the support assembly; S432: The pushing mechanism pushes the epitaxial wafer to the opening of the isolation plate again to fall into the collection device, and drives the sorting execution mechanism to move according to the defect detection result, so as to store the qualified epitaxial wafer, the over-thick defect epitaxial wafer and the over-thin defect epitaxial wafer in different partitions of the collection device.

[0039] In this example, the control of the incomplete gear structure continues to rotate, when it turns through the 240° toothless non-drive area, it enters the remaining 120° toothed area and reversely engages with the third gear, at this time the engagement direction is opposite to the descending stage, the intermediate transmission gear is driven to rotate reversely, the second transmission shaft connected coaxially with the intermediate transmission gear is reversely rotated, and then the lifting driving mechanism is moved in the reverse direction. The second reciprocating screw rod in the lifting driving mechanism drives the nut pair engaged with it to move axially under the reverse rotation, the second bearing seat rigidly connected with the nut pair uniformly rises under the constraint of the guide mechanism, and drives the limit block, adjusting rod and first telescopic rod connected therewith to move upward as a whole. Since the detection block is fixed at the bottom end of the telescopic rod, the detection block synchronously rises along the guide track in this process and gradually separates from the surface of the epitaxial wafer until it returns to the initial position of the rising, at this time the elastic element completes the energy release from the compressed state to the pre-compressed state, and the detection block returns to the standby state. The slide mode control system restarts the pushing mechanism, and performs a complete horizontal pushing action through the L-shaped block to push the detected epitaxial wafer from the detection position to the discharge end position. An isolation plate opening structure is arranged above the discharge end, and the epitaxial wafer slides into the opening under the pushing of the L-shaped block and falls vertically into the collecting device below the isolation plate under the action of gravity. According to the defect mark D(i) generated in the previous thickness detection process, the sorting execution mechanism is automatically controlled to act, if D(i)=0, it indicates that the epitaxial wafer is qualified, the push plate is controlled to keep the neutral position, and the epitaxial wafer falls freely into the qualified area on the left side of the collecting device; if D(i)=1, it indicates that the epitaxial wafer has an over-thickness defect, the push plate is offset by a preset distance Δx l to the one side, so that the epitaxial wafer enters the middle over-thickness defect storage area; if D(i)=2, it indicates that the epitaxial wafer is an under-thickness defect, the push plate is offset by a distance Δx r to the other side, so that the epitaxial wafer enters the right under-thickness defect area. The entire sorting process is one-to-one corresponding to the sorting control signal and the defect code, and after the action is completed, the push plate is immediately reset, ready to accept the defect sorting instruction of the next epitaxial wafer.

[0040] With reference Figure 2 , the embodiment provides an epitaxial wafer defect detection device of a light emitting diode, which is used for executing steps of an epitaxial wafer defect detection method of a light emitting diode, and comprises: The feeding pipe is used for feeding the epitaxial wafer to be detected; the driving device is arranged at the top of the device, and the driving device is connected with the rotary transmission mechanism through an output shaft; the pushing mechanism is connected with the rotary transmission mechanism through a transmission conversion mechanism, and is used for pushing the epitaxial wafer to a detection position; the gear transmission system is arranged between the driving device and the screw driving mechanism, and comprises a main transmission shaft, a first-stage bevel gear transmission mechanism, a second-stage bevel gear transmission mechanism, a third-stage bevel gear transmission mechanism and an intermediate transmission shaft which are sequentially engaged and transmitted; the screw driving mechanism is connected with the intermediate transmission shaft through a spur gear transmission mechanism, and a moving seat is arranged outside the screw driving mechanism; the moving seat is connected with the screw driving mechanism through a nut pair; the transmission assembly is fixedly connected to the moving seat, and the transmission assembly controls the pushing speed of the pushing mechanism through the transmission conversion mechanism; the transmission gear system is arranged on one side of the transmission assembly, and comprises a driving bevel gear, a driven bevel gear and a first transmission shaft; the driving bevel gear is fixed outside the transmission assembly, the driven bevel gear is engaged with the driving bevel gear and is fixed to the first transmission shaft; the intermittent transmission mechanism is fixed outside the first transmission shaft, and has an effective transmission area and a non-transmission area; the driven gear and a second transmission shaft are intermittently engaged with the effective transmission area of the intermittent transmission mechanism, and the driven gear is fixed to the second transmission shaft; the lifting driving mechanism is connected with the second transmission shaft, and a lifting seat is arranged outside the lifting driving mechanism; the lifting seat is connected with the lifting driving mechanism through a nut pair; the guide mechanism is used for moving the lifting seat up and down; the supporting assembly, the adjusting rod and the telescopic rod are fixed to the lifting seat, the adjusting rod and the bottom end of the telescopic rod respectively; the detection block is fixed to the bottom end of the telescopic rod; the elastic element is arranged outside the telescopic rod, and exerts a pre-tightening force on the detection block; the displacement measuring device is used for measuring the height of the bottom surface of the detection block; the isolation plate is arranged inside the device, and an opening is arranged at the top of the isolation plate; the collecting device is fixed to the bottom of the isolation plate, and a plurality of sub-areas are arranged inside the collecting device; the sorting execution mechanism is arranged inside the collecting device, and is used for storing the epitaxial wafer in different sub-areas according to the defect judgment result.

[0041] In the embodiments of the device, the specific implementation of each unit can refer to the description in the method embodiments, and will not be repeated here.

[0042] It should be noted that in this paper, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, device, article or method including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, device, article or method. Without more limitations, the element defined by the statement "including a" does not exclude the existence of other identical elements in the process, device, article or method including the element.

[0043] The above merely describes preferred embodiments of the present application, and is not intended to limit the patent scope of the present application, and any equivalent structure or equivalent process conversion, or direct or indirect application in other related technical fields, which are made by using the content of the present application specification and drawings, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting defects in the epitaxial wafer of a light-emitting diode, characterized in that, include: S1: Insert the epitaxial wafer into the feed tube and start the drive device to drive the pushing mechanism. Adjust the drive device to push the epitaxial wafer to the detection position. S2: The transmission component drives the transmission gear system to mesh, which in turn drives the intermittent transmission mechanism to mesh intermittently with the driven gear, causing the lifting drive mechanism to rotate and drive the detection block to descend and contact the outer extension plate under spring loading. S3: Measure the height of the bottom surface of the test block and calculate the thickness of the epitaxial wafer; S4: Determine the defect detection results based on the epitaxial wafer thickness and standard thickness, and control the sorting execution mechanism to store the wafers in designated areas according to the defect detection results.

2. The method for detecting defects in the epitaxial wafer of a light-emitting diode according to claim 1, characterized in that, Step S1 includes: S11: The epitaxial wafer is fed into the feed tube and slid down to the push waiting position. The drive device is started to drive the reciprocating linear push motion of the push mechanism. S12: Set the initial displacement and initial velocity of the pushing mechanism, based on the velocity difference between the target velocity and the initial velocity; S13: Construct a sliding mode switching function based on the speed difference and its integral term, set the switching gain coefficient of the sliding mode switching function, and set the control gain and adaptive gain coefficient according to the absolute value of the sliding mode switching function; S14: Collect the pushing displacement and pushing speed of the pushing mechanism and adjust the output torque of the drive device to control the pushing speed, pushing the epitaxial wafer to the detection position.

3. The method for detecting defects in the epitaxial wafer of a light-emitting diode according to claim 2, characterized in that, Step S13 includes: S131: Integrate the speed difference over time to obtain the integral term and set the switching gain coefficient of the sliding mode switching function. Construct the sliding mode switching function based on the speed difference, the switching gain coefficient, and the integral term. S132: Set the control gain, and set the corresponding adaptive gain coefficient according to the chattering requirements of the sliding mode switching function.

4. The method for detecting defects in the epitaxial wafer of a light-emitting diode according to claim 2, characterized in that, Step S14 includes: S141: The displacement measuring device measures the pushing displacement of the pushing mechanism and calculates the pushing speed, and updates the sliding mode switching function based on the target speed and the pushing speed; S142: Determine the sign of the sliding mode switching function, calculate the output torque adjustment of the drive device based on the control gain and the sign of the sliding mode switching function, and transmit it to the screw drive mechanism through the gear transmission system to drive the pushing mechanism to adjust the pushing speed; S143: Control the pushing mechanism to push the epitaxial wafer. When the pushing displacement reaches the target pushing distance, the pushing stops, and the epitaxial wafer at the detection position is obtained.

5. The method for detecting epitaxial wafer defects of a light-emitting diode according to claim 4, characterized in that, Step S142 includes: S1421: Determine the sign of the sliding mode switching function. When the sign is positive, output a deceleration command; when the sign is negative, output an acceleration command. Multiply the control gain by the sign of the sliding mode switching function and take the negative value to obtain the output torque adjustment of the drive device. S1422: The output torque adjustment of the drive unit is transmitted to the intermediate drive shaft through the gear transmission system driven by the main drive shaft. S1423: The intermediate drive shaft drives the screw drive shaft to rotate through the flat gear transmission mechanism, and the screw drive mechanism drives the moving seat and transmission assembly to move through the nut pair. The transmission assembly controls the pushing speed of the pushing mechanism through the transmission conversion mechanism.

6. The method for detecting defects in the epitaxial wafer of a light-emitting diode according to claim 1, characterized in that, Step S2 includes: S21: The rotation of the transmission component drives the active bevel gear in the transmission gear system to mesh with the driven bevel gear. The driven bevel gear drives the first transmission shaft to rotate. The intermittent transmission mechanism outside the first transmission shaft intermittently meshes with the driven gear in the effective transmission area, driving the second transmission shaft to rotate and driving the lifting drive mechanism to rotate. S22: The lifting drive mechanism drives the lifting seat to descend along the guide mechanism through the nut pair. The support assembly fixed by the lifting seat drives the adjusting rod and the telescopic rod to descend. The detection block at the bottom of the telescopic rod contacts the surface of the epitaxial sheet under the pre-tightening force of the elastic element.

7. The method for detecting defects in the epitaxial wafer of a light-emitting diode according to claim 1, characterized in that, Step S3 includes: S31: When the detection block is kept in a squeezed state, the displacement measuring device measures the height of the bottom surface of the detection block at the first sampling time to obtain the first measurement height, and measures the second measurement height at the second sampling time after a set interval, and measures the third measurement height at the third sampling time after a set interval. S32: Add the first measurement height, the second measurement height and the third measurement height and divide by three to get the average height value. Calculate the height difference between the average height value and the reference value of the detection block height. Calculate the difference between the target compression amount of the elastic element and the difference between the descent distance and the height difference of the lifting drive mechanism to get the compression amount deviation of the elastic element. Multiply the compression amount deviation of the elastic element by the spring compression amount deviation compensation coefficient to get the compensation amount. Add the standard epitaxial sheet thickness to the difference and the compensation amount to get the epitaxial sheet thickness.

8. The method for detecting defects in the epitaxial wafer of a light-emitting diode according to claim 1, characterized in that, Step S4 includes: S41: Subtract the thickness of the epitaxial wafer from the thickness of the standard epitaxial wafer to obtain the thickness difference; S42: Determine the relationship between the thickness difference and the thickness difference threshold. When the thickness difference is greater than the thickness difference threshold, mark the defect detection result as an excessively thick defect. When the thickness difference is less than the negative value of the thickness difference threshold, mark the defect detection result as an excessively thin defect. When the absolute value of the thickness difference is less than or equal to the thickness difference threshold, mark the defect detection result as qualified. S43: The intermittent transmission mechanism reverses the engagement to drive the detection block to rise and disengage from the epitaxial wafer. The pushing mechanism pushes the epitaxial wafer to the collection device. Based on the defect detection results, the sorting execution mechanism is controlled to store the wafer in designated areas.

9. The method for detecting epitaxial wafer defects of a light-emitting diode according to claim 8, characterized in that, Step S43 includes: S431: After the intermittent transmission mechanism passes through the non-transmission area, it engages the driven gear in the opposite direction, driving the lifting drive mechanism to rotate in the opposite direction. Through the lifting seat and support assembly, it drives the detection block to rise along the guide mechanism and detach from the surface of the epitaxial wafer. S432: The pushing mechanism pushes the epitaxial wafer again to the opening of the isolation plate and it falls into the collection device. Based on the defect detection results, the sorting execution mechanism is driven to move and store the qualified epitaxial wafer, the excessively thick defective epitaxial wafer, and the excessively thin defective epitaxial wafer in different partitions of the collection device.

10. A device for detecting defects in the epitaxial wafer of a light-emitting diode, characterized in that, The steps are for implementing the epitaxial wafer defect detection method for any one of claims 1 to 9 of a light-emitting diode.

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