Splitting method

Abstract

Provided is a cleaving method, belonging to the field of semiconductor manufacturing. The method comprises: attaching a first blue film to one side of a light-emitting diode chip away from a sapphire substrate, the thickness of the normal light-emitting diode chip being not less than 200 microns; using a bifocal laser to perform scribing treatment on the other side of the light-emitting diode chip; during the scribing treatment, the distance between the two focal points of the laser emitted by the bifocal laser in the light-emitting diode chip is controlled to be 25-30 microns, the point spacing of the non-bevelled cleaving surface of the sapphire substrate is controlled to be 5-7 microns, and the point spacing of the bevelled cleaving surface of the sapphire substrate is controlled to be 9-10 microns; the parameters of the bifocal laser, the light-emitting angle of the bifocal laser, and the power of the bifocal laser are controlled, so that the laser is irradiated onto the line of the light-emitting diode chip, and the fluctuation range of the line is-2 microns to 2 microns; and a cleaving knife is used to perform cleaving on the scribed light-emitting diode chip.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor manufacturing, and in particular, to a scribing method. BACKGROUND

[0002] With the continuous development of technology, consumption is constantly upgraded, and cultural entertainment accounts for a growing proportion of household consumption. Under the increasing demand for household entertainment, large-screen display technology has also undergone a number of breakthrough innovations, from cathode ray tube (CRT) displays to liquid crystal displays (LCDs). LCD technology is also constantly innovating. For example, LCD backlights have evolved from using cold cathode fluorescent lamps (CCFL) backlights to using light emitting diodes (LEDs) as backlights, resulting in more realistic color effects, higher brightness, and higher energy efficiency.

[0003] LEDs are divided into flip-chip LEDs and vertical LEDs. Flip-chip LED products have inverted trapezoidal scribe lanes, while vertical LED products have rectangular scribe lanes. The minimum width of the bottom of the inverted trapezoidal scribe lane for flip-chip LEDs is currently 12 μm, while the minimum width of the bottom of the rectangular scribe lane for vertical LEDs is currently 14 μm. How to use inverted trapezoidal scribe lanes for vertical high-voltage LED chips (a type of vertical LED chip) and reduce the width of the bottom of the inverted trapezoidal scribe lane to 10 μm is a current technical difficulty. The reason is that a too-narrow scribe lane bottom can cause problems such as unexploded products, electrode lifting, scribe lane debris, and backside glue filaments during the scribing process, thereby affecting product appearance yield and electrical performance yield. SUMMARY

[0004] Embodiments of the present disclosure provide a scribing method that can avoid electrode lifting and other issues, thereby improving product yield. The technical solution is as follows:

[0005] At least one embodiment of the present disclosure provides a scribing method suitable for vertical light emitting diode chips with sapphire substrates. The method includes:

[0006] Attaching a first blue film to the side of the light emitting diode chip that is farthest from the sapphire substrate, wherein the thickness of the vertical light emitting diode chip is not less than 200 microns;

[0007] slicing the other side of the light emitting diode chip by using a bifocal laser; during the slicing, the distance between the two focal points of the laser emitted by the bifocal laser in the light emitting diode chip is controlled to be 25-30 μm, the point distance of the non-inclined fracture surface of the sapphire substrate is controlled to be 5-7 μm, and the point distance of the inclined fracture surface of the sapphire substrate is controlled to be 9-10 μm; the parameters of the bifocal laser, the light emission angle of the bifocal laser, and the power of the bifocal laser are controlled so that the fluctuation range of the line on the light emitting diode chip irradiated by the laser is-2 μm to 2 μm;

[0008] slicing the light emitting diode chip by using a bifocal laser; during the slicing, the distance between the two focal points of the laser emitted by the bifocal laser in the light emitting diode chip is controlled to be 25-30 μm, the point distance of the non-inclined fracture surface of the sapphire substrate is controlled to be 5-7 μm, and the point distance of the inclined fracture surface of the sapphire substrate is controlled to be 9-10 μm; the parameters of the bifocal laser, the light emission angle of the bifocal laser, and the power of the bifocal laser are controlled so that the fluctuation range of the line on the light emitting diode chip irradiated by the laser is-2 μm to 2 μm;

[0009] Optionally, the method further comprises:

[0010] Before slicing, the parameters of the bifocal laser, the light emission angle of the bifocal laser, and the power of the bifocal laser are determined as follows:

[0011] using a U-FAST bifocal laser, taking the blasting effect and the line straightness as the optimization targets, stepwise adjusting the parameters of the U-FAST bifocal laser to obtain first laser parameter values, the parameters of the U-FAST bifocal laser including DW0, DW1, and PK26PA values;

[0012] using the first laser parameter values as the parameters of the U-FAST bifocal laser, taking the line deviation as the optimization target, stepwise adjusting the light emission angle of the U-FAST bifocal laser to obtain a first laser light emission angle, the light emission angle of the U-FAST bifocal laser including a non-inclined fracture surface light emission angle and an inclined fracture surface light emission angle;

[0013] using the first laser parameter values as the parameters of the U-FAST bifocal laser and using the first laser light emission angle as the light emission angle of the U-FAST bifocal laser, taking the line fluctuation range as the optimization target, stepwise adjusting the power of the U-FAST bifocal laser to obtain a first laser power;

[0014] the first laser parameter values, the first laser light emission angle, and the first laser power are the parameters of the bifocal laser, the light emission angle of the bifocal laser, and the power of the bifocal laser used during slicing.

[0015] Optionally, the DW0, DW1, and PK26PA values are 15-20, 15-20, and 8-9, respectively.

[0016] The non-bevel facet light emitting angle and the bevel facet light emitting angle are 55° and 84° respectively.

[0017] Optionally, a blue film is attached to one side of the light emitting diode chip, comprising:

[0018] The light emitting diode chip is placed on a base with a nano vacuum hole, and vacuum is used for adsorption, with an adsorption pressure less than or equal to -80 kPa.

[0019] In the adsorbed state, the first blue film is attached to one side of the light emitting diode chip.

[0020] Optionally, the viscosity of the first blue film is less than or equal to 0.3 N / 20 mm, and the diameter of the first blue film is 255-260 mm.

[0021] Optionally, during the scribing process, the laser frequency of the non-bevel facet of the sapphire substrate is 90-110 Hz, and the scribing speed is 450-630 mm / s; the laser frequency of the bevel facet of the sapphire substrate is 45-55 Hz, and the scribing speed is 450-550 mm / s.

[0022] Optionally, the method further comprises:

[0023] The sapphire substrate is preferentially split along the bevel facet in the direction from the edge to the center of the light emitting diode chip.

[0024] Optionally, during the splitting process, a force of 2-3 μm is used.

[0025] Optionally, the method further comprises:

[0026] The second blue film is attached to the metal ring.

[0027] The split light emitting diode chip is attached to the second blue film of the metal ring for pressing.

[0028] One side of the light emitting diode chip is placed on a nano vacuum disc for adsorption, and the first blue film is removed.

[0029] The second blue film is expanded to separate the split light emitting diode chip.

[0030] Optionally, during the pressing process, the pressing time is 8-12 s, and the pressing pressure is less than or equal to -0.6 MPa.

[0031] Optionally, the method further comprises:

[0032] Place the expanded film light emitting diode chip on the optical display mirror to perform the inclined plate inspection, and observe the electrode lifting of the edge of the light emitting diode chip.

[0033] The technical solution provided by the embodiments of the present disclosure has the following beneficial effects:

[0034] In the scheme of the present disclosure, when the scribing of the light emitting diode chip is performed, the distance of the two focal points of the bifocal laser in the light emitting diode chip is controlled to be 25-30 μm, the point spacing of the non-inclined fracture surface of the sapphire substrate is controlled to be 5-7 μm, the point spacing of the inclined fracture surface of the sapphire substrate is controlled to be 9-10 μm, and the parameters of the bifocal laser, the light emitting angle of the bifocal laser and the power of the bifocal laser are controlled, so that the line fluctuation range of the laser irradiated on the light emitting diode chip is-2 μm to 2 μm. By providing more energy by the bifocal laser, the two sides of the light emitting diode chip can be scribed in the case of a thicker sapphire substrate; and by controlling the point spacing, the parameters of the bifocal laser, the light emitting angle of the bifocal laser and the power of the bifocal laser, the flip light emitting diode chip is processed, so that this scribing mode cooperates with the above laser focal length to ensure that the inverted trapezoidal scribing channel with a bottom width of 10 microns or less is formed on the flip light emitting diode, and has good scribing precision, thereby ensuring the appearance yield and electrical yield of the flip light emitting diode chip. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without creative labor.

[0036] Figure 1 is a flowchart of a scribing method provided by some embodiments of the present disclosure;

[0037] Figure 2 is a flowchart of a scribing method provided by some embodiments of the present disclosure;

[0038] Figure 3 is an abnormality schematic diagram of a product provided by some embodiments of the present disclosure;

[0039] Figure 4 is an abnormality schematic diagram of a product provided by some embodiments of the present disclosure. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in combination with the drawings.

[0041] Figure 1 is a flow chart of a cleaving method provided by some embodiments of the present disclosure. The method is a cleaving method applied to a light emitting diode chip, referring to Figure 1 , the method comprises:

[0042] S11: attaching a first blue film to a side of the light emitting diode chip away from the sapphire substrate, the thickness of the normal light emitting diode chip is not less than 200 microns.

[0043] In the embodiments of the present disclosure, the normal light emitting diode is targeted, and the thickness of the sapphire substrate is relatively thick, for example, the thickness of the normal light emitting diode chip is 200 microns. Wherein, the normal light emitting diode refers to a light emitting diode with the light emitting surface away from the substrate.

[0044] The size of a single chip after the light emitting diode is cleaved can be 730 microns by 266 microns.

[0045] S12: using a bifocal laser to perform a scribing process on the other side of the light emitting diode chip; during the scribing process, the distance between the two focal points of the laser emitted by the bifocal laser in the light emitting diode chip is controlled to be 25-30 microns, the point spacing of the non-oblique cleavage surface of the sapphire substrate is controlled to be 5-7 microns, and the point spacing of the oblique cleavage surface of the sapphire substrate is controlled to be 9-10 microns; the parameters of the bifocal laser, the light emitting angle of the bifocal laser and the power of the bifocal laser are controlled, so that the line fluctuation range of the laser irradiated on the light emitting diode chip is-2 microns to 2 microns.

[0046] Wherein, the method of the present disclosure is used to form an inverted trapezoidal scribing channel in the normal light emitting diode chip, the opening width of the inverted trapezoidal scribing channel is 14 microns, and the bottom width is 10 microns. Compared with the rectangular scribing channel with the bottom and opening width of 14 microns, the number of integrated chip pieces in the wafer of the same area can be increased, the single chip cost can be reduced, and the product market competitiveness can be increased.

[0047] Wherein, the point spacing size is usually related to the scribing speed and the laser frequency. For example, the point spacing can be defined as the ratio (unit is microns) of the value of the scribing speed (unit is mm / s) and the value of the laser frequency (unit is Hz). Since the power required by the non-oblique cleavage surface is large, the point spacing is smaller, that is, the dot is more dense. Such numerical design is more in line with the scribing demand, and ensures the scribing quality.

[0048] The parameters of the bifocal laser include DW0, DW1 and PK26PA, and the DW0, DW1 and PK26PA are used to control the peak frequency of the laser. The light-emitting angle of the bifocal laser includes a non-oblique facet light-emitting angle and an oblique facet light-emitting angle. The power of the bifocal laser is the output power of the bifocal laser.

[0049] The DW0 is a short name of DWQINIT0, the DW1 is a short name of DWQINIT1, and the PK26PA is a short name of PK26PARA, all of which are adjustable parameters of the U-FAST bifocal laser.

[0050] In addition, the distance from the focus point far from the sapphire substrate to the surface of the sapphire substrate is 80-95 mu m, and a bidirectional scribing method is used for processing.

[0051] The other side of the light-emitting diode chip can be the back of the light-emitting diode chip, that is, one side of the substrate.

[0052] In the embodiment of the present disclosure, bidirectional scribing, that is, S-shaped scribing, that is, along the track from A end to B end, and then from B end to A end, laser scribing is performed in the process of coming and going.

[0053] In the embodiment of the present disclosure, the two focal points of the laser emitted by the bifocal laser are arranged along the thickness direction of the substrate. The bifocal laser makes the energy entering the chip interior larger, and the laser energy is more likely to cause the front and back of the light-emitting diode chip to crack.

[0054] The depth of the two focal points of the bifocal laser and the distance between the two focal points can be controlled by the laser.

[0055] S13: using a cleaver to crack the scribed light-emitting diode chip.

[0056] In the related art, the cleaver angle is 70°, and the embodiment of the present disclosure can use a larger angle, for example, 70° to 80°, so as to facilitate the cracking of large-size light-emitting diode chips.

[0057] It should be noted that the light-emitting diode chip in the embodiment of the present disclosure is a wafer before scribing, and the wafer includes a plurality of light-emitting diode chip units. After cracking, it becomes a die, and each die is a light-emitting diode chip unit.

[0058] In the scheme of the present disclosure, when the scribing of the light emitting diode chip is performed, the distance of the two focal points of the bifocal laser in the light emitting diode chip is controlled to be 25-30 μm, the point spacing of the non-bevel surface of the sapphire substrate is controlled to be 5-7 μm, the point spacing of the bevel surface of the sapphire substrate is controlled to be 9-10 μm, and the parameters of the bifocal laser, the light emitting angle of the bifocal laser and the power of the bifocal laser are controlled, so that the line fluctuation range of the laser irradiated on the light emitting diode chip is-2 μm to 2 μm. More energy is provided by the bifocal laser, so that in the case of a thicker sapphire substrate, the two sides of the light emitting diode chip can be scribed; and by controlling the point spacing, the parameters of the bifocal laser, the light emitting angle of the bifocal laser and the power of the bifocal laser, the flip light emitting diode chip is processed, so that this scribing mode cooperates with the above laser focal length to ensure that the inverted trapezoidal scribing groove with a bottom width of 10 microns or less is formed on the flip light emitting diode, and has good scribing precision, thereby ensuring the appearance yield and electrical yield of the flip light emitting diode chip.

[0059] Figure 2 is a flowchart of another scribing method provided by some embodiments of the present disclosure. The method is a scribing method applied to a light emitting diode chip. Referring to Figure 2 , the method comprises:

[0060] S21: placing the light emitting diode chip on the machine base with a nano vacuum hole, and using vacuum adsorption with an adsorption pressure less than or equal to-80 kPa.

[0061] S22: attaching the first blue film to one side of the light emitting diode chip in the adsorbed state.

[0062] Wherein, one side of the light emitting diode chip can be the front side of the light emitting diode chip, that is, the side away from the substrate.

[0063] In this implementation, by first vacuum adsorbing the light emitting diode chip and then attaching the blue film, the attachment quality can be ensured.

[0064] In the embodiments of the present disclosure, the viscosity of the first blue film is less than or equal to 0.3 N / 20 mm, and the diameter of the first blue film is 255-260 mm.

[0065] Exemplarily, the diameter of the first blue film is 258 mm.

[0066] Exemplarily, the first blue film can be attached to an iron ring with a diameter of 210 mm first, and then one side of the light emitting diode chip is attached to the first blue film.

[0067] In the implementation, the blue film with the above viscosity can ensure the adhesion to the light emitting diode chip and ensure the normal subsequent scribing.

[0068] S23: scribe the other surface of the light emitting diode chip using a bifocal laser; during the scribing, the distance between the two focal points of the laser emitted by the bifocal laser in the light emitting diode chip is controlled to be 25-30 μm, the point distance of the non-bevel surface of the sapphire substrate is controlled to be 5-7 μm, and the point distance of the bevel surface of the sapphire substrate is controlled to be 9-10 μm; the parameters of the bifocal laser, the light emission angle of the bifocal laser, and the power of the bifocal laser are controlled, so that the line fluctuation range of the laser irradiated on the light emitting diode chip is-2 μm to 2 μm.

[0069] The point distance is generally related to the scribing speed and the laser frequency. For example, the point distance can be defined as the ratio (in μm) of the value of the scribing speed (in mm / s) and the value of the laser frequency (in Hz). Since the power required by the non-bevel surface is large, the point distance is smaller, that is, the dot is more dense, and such a numerical design is more in line with the scribing requirements and ensures the scribing quality.

[0070] The parameters of the bifocal laser include DW0, DW1, and PK26PA value, which are used to control the peak frequency of the laser. The light emission angle of the bifocal laser includes the light emission angle of the non-bevel surface and the light emission angle of the bevel surface. The power of the bifocal laser is the output power of the bifocal laser.

[0071] In addition, the distance between the focal point far from the sapphire substrate in the two focal points and the surface of the sapphire substrate is 80-95 μm, and a bidirectional scribing method is used for processing.

[0072] In the scheme of the present disclosure, when dicing a light emitting diode chip, the distance between the two focal points of a bifocal laser in the light emitting diode chip is controlled to be 25-30 μm, the point spacing of the non-bevel surface of the sapphire substrate is controlled to be 5-7 μm, the point spacing of the bevel surface of the sapphire substrate is controlled to be 9-10 μm, and the parameters of the bifocal laser, the light emission angle of the bifocal laser and the power of the bifocal laser are controlled so that the line fluctuation range of the laser irradiated on the light emitting diode chip is -2 μm to 2 μm. By providing more energy through the bifocal laser, the two sides of the light emitting diode chip can be cut in the case of a thicker sapphire substrate; and by controlling the point spacing, the parameters of the bifocal laser, the light emission angle of the bifocal laser and the power of the bifocal laser to process the normal light emitting diode chip, this dicing method can ensure that an inverted trapezoidal dicing lane with a bottom width of 10 microns or less is formed on the normal light emitting diode, and has good dicing precision, thereby ensuring the appearance yield and electrical yield of the normal light emitting diode chip.

[0073] For example, in the dicing process, the distance between the two focal points of the laser emitted by the bifocal laser in the light emitting diode chip is controlled to be 28 μm, and the distance from the focal point farther from the sapphire substrate to the surface of the sapphire substrate is 92 μm.

[0074] In the embodiment of the present disclosure, during the dicing process, the laser frequency of the non-bevel surface of the sapphire substrate is 90-110 Hz, and the dicing speed is 450-630 mm / s; the laser frequency of the bevel surface of the sapphire substrate is 45-55 Hz, and the dicing speed is 450-550 mm / s.

[0075] In the embodiment of the present disclosure, the bevel surface of the sapphire substrate, i.e. the cleavage surface of the sapphire substrate, refers to a surface that will break along a certain crystal face net under external force.

[0076] In combination with the above dicing speed and laser frequency, the distance of the laser focal point at the bevel surface of the sapphire substrate is different from the distance at the non-bevel surface, for example, at the bevel surface, the distance from the focal point farther from the sapphire substrate to the surface of the sapphire substrate is 90-95 μm, and at the non-bevel surface, the distance from the focal point farther from the sapphire substrate to the surface of the sapphire substrate is 80-90 μm.

[0077] For example, when dicing, the laser dices according to the set trajectory, if the actual dicing trajectory deviates from the set trajectory, it is a bevel surface, and the laser is controlled according to the focal depth of the bevel surface. If the actual dicing trajectory is consistent with the set trajectory, it is a non-bevel surface, and the laser is controlled according to the focal depth of the non-bevel surface.

[0078] In this implementation, by using the aforementioned power and dicing speed, compared to related technologies, the laser power is reduced and the dicing machine speed is lowered, thus ensuring the dicing effect.

[0079] For example, during the dicing process, the laser frequency on the non-cleft surface of the sapphire substrate is 100Hz and the dicing speed is 500mm / s; the laser frequency on the cleft surface of the sapphire substrate is 50Hz and the dicing speed is 450mm / s.

[0080] In this embodiment of the disclosure, the power control of the dual-focus laser enables the line fluctuation range of the laser irradiation on the light-emitting diode chip to be from -2μm to 2μm.

[0081] Furthermore, during the debugging process, the power of the dual-focus laser can prevent the chip from failing to crack during three consecutive dicing passes (no cracks appear on both sides of the chip during the dicing process).

[0082] In this implementation, the grading quality can be further guaranteed by controlling the fluctuation of the grading lines.

[0083] The lines produced by dicing are typically straight lines with a fluctuation range of -2μm to 2μm, meaning they fluctuate 2μm to either side of the originally designed straight path. In conventional LED dicing schemes, the fluctuation range of the lines produced is too large for the LED chip, thus requiring control of the fluctuation range. This disclosure addresses this issue by controlling the laser power to achieve a line fluctuation range of -2μm to 2μm, avoiding problems such as misalignment of the back-side lines and uneven edge size of the product, thereby resolving the aforementioned appearance abnormalities.

[0084] In addition, when slicing, it is necessary to ensure that both the front and back sides are completely cut. When slicing, attention should be paid to the lines on the back of the product, and wavy or misaligned lines should be avoided.

[0085] In this embodiment of the disclosure, the laser may be a U-FAST dual-focus laser.

[0086] In this embodiment of the disclosure, the method further includes:

[0087] Before dicing, the parameters of the dual-focus laser, the output angle of the dual-focus laser, and the power of the dual-focus laser are determined as follows:

[0088] The first step involves using a U-FAST dual-focus laser, with the explosion effect and line straightness as optimization targets, and adjusting the parameters of the U-FAST dual-focus laser in a stepwise manner to obtain the first laser parameter values. The parameters of the U-FAST dual-focus laser include DW0, DW1, and PK26PA values.

[0089] Among them, DW0 is short for DWQINIT0, DW1 is short for DWQINIT1, and PK26PA is short for PK26PARA. These are all adjustable parameters of the U-FAST dual-focus laser.

[0090] Adjusting DW0, DW1, and PK26PA aims to regulate the peak power of the laser. Lower values ​​for DW0, DW1, and PK26PA result in higher peak power and lower power required for product cracking. Therefore, optimizing appropriate values ​​for DW0, DW1, and PK26PA can improve the reverse leakage current (IR) and forward voltage (VF) yield of the scratched product. DW0 primarily controls the peak power at 100Hz, while DW1 controls the peak power at 50Hz. The default range for DW0 and DW1 is 8–99, and the default range for PK26PA is 4.5–15. Based on the cracking effect and the straightness of the back lines, DW0 and DW1 are adjusted in units of 5. If the initial value of laser DW0 and DW1 is 90, it is decreased in units of 5 to obtain a range of 15 to 20 suitable for this disclosure. The PK26PA is adjusted in units of 0.5. If the initial value of the laser is 10, it is decreased in units of 0.5. When the cracking effect and the back lines are close to meeting the process requirements, it needs to be fine-tuned in units of 0.1 until the process requirements are met, to obtain a range of 8 to 9 suitable for this disclosure.

[0091] In this embodiment of the disclosure, the process requirement may be the best result within a number of trials, or a benchmark may be set as the process requirement, and there is no limitation thereto.

[0092] The second step involves using the first laser parameter value as the parameter of the U-FAST dual-focus laser, and adjusting the output angle of the U-FAST dual-focus laser in steps with the line deviation as the optimization target to obtain the first laser output angle. The output angle of the U-FAST dual-focus laser includes the non-oblique crack surface output angle and the oblique crack surface output angle.

[0093] Here, adjusting the laser's output angle refers to adjusting the motorized lever of the U-FAST dual-focus laser. This lever consists of a motor and a polarizer; the motor controls the rotation of the polarizer, thereby adjusting the output angle. The default output angle of the U-FAST dual-focus laser is 90 degrees when not controlled, and the adjustments disclosed herein are based on this.

[0094] After the laser parameters are optimized, the laser emission angle is adjusted to ensure that the center line of each scribe line is in the predetermined position, rather than deviating from it. The laser emission angle is mainly adjusted by a motorized lever. The default angle for non-oblique scribe lines is 45°, and the default angle for oblique scribe lines is 90°. The adjustment is done in steps, for example, adjusting by 1 degree each time. The deviation is checked by the scriber itself to determine the optimal angle (center line deviation within 1 micrometer). The emission angle for non-oblique scribe lines is 55°, and the emission angle for oblique scribe lines is 84°.

[0095] Among them, line deviation refers to the distance between the actual center line and the set center line.

[0096] The third step involves using the first laser parameter value as the parameter of the U-FAST dual-focus laser and the first laser output angle as the output angle of the U-FAST dual-focus laser, with the line fluctuation range as the optimization target, and adjusting the power of the U-FAST dual-focus laser in steps to obtain the first laser power.

[0097] The fluctuation range refers to the distance between the highest and lowest points of the line and the center line.

[0098] After adjusting the laser parameters and laser emission angle as described above, the optimal power was determined by testing the cracking effect of the product. Adjustments were made in 20mW increments. The optimal power was achieved when both sides cracked within 1-2 seconds during the observation of the cracking effect. During power adjustment, it was crucial to avoid more than three consecutive instances of failure to crack. The wave pattern on the back side should be controlled within 2μm fluctuations to ensure a high dicing yield. The final determined power is product-specific and not limited here.

[0099] The first laser parameter values, the first laser emission angle, and the first laser power are the parameters of the dual-focus laser used during dicing, the emission angle of the dual-focus laser, and the power of the dual-focus laser.

[0100] Using the above method, the DW0, DW1 and PK26PA values ​​were finally determined to be 15-20, 15-20 and 8-9, respectively.

[0101] The light emission angles of the non-oblique crack surface and the oblique crack surface are 55° and 84°, respectively.

[0102] In this embodiment of the disclosure, the laser power determined by the above method is relatively small, which causes less damage to the LED chip during dicing and results in a high electrical yield of the LED chip.

[0103] In this embodiment of the disclosure, the dual-focus laser further includes a beam expander disposed between the laser and the light-emitting diode chip, the beam expander being used to control the laser spot size to 5 mm to 7 mm.

[0104] By setting a beam expander to control the beam width (the width of the beam generated by the laser irradiating the chip surface), the laser is made more suitable for dicing LED chips.

[0105] In this embodiment of the disclosure, the beam expander can be a 1.5 to 2x beam expander.

[0106] In this embodiment, the distance between the beam expander and the laser can be adjusted as needed, as long as the requirements for the line fluctuation range and the chamfer angle are ultimately met.

[0107] S24: The diced LED chip is split using a cleaver.

[0108] When dicing, a dicing blade with a dicing angle of 70° to 80° is selected, as this angle is beneficial for dicing thicker sapphire substrates. This design avoids poor dicing on the side furthest from the sapphire substrate during dicing, which could cause slight electrode warping and improve the yield of micro-LED products.

[0109] For example, the dicing diode chip is diced using a dicing blade with a dicing angle of 75°.

[0110] In this embodiment of the disclosure, during the chip splitting process, a force of 2-3 μm is applied to the spacing between the LED chips under chip splitting adjustment conditions. Furthermore, the blade is struck twice consecutively with a hammer during chip splitting.

[0111] The LED chip spacing here refers to the distance between adjacent LED chips after they have been split by a cleaver. The splitting and debugging process is performed before the actual splitting.

[0112] In this implementation, the LED chip spacing is 2-3 μm and the chip is split with force during the splitting adjustment, which ensures the quality of the splitting and avoids the electrodes from lifting.

[0113] For example, during the chip splitting process, the spacing between the LED chips is 2.5 μm under chip splitting debugging conditions.

[0114] In this embodiment of the disclosure, before splitting the wafer, the distance between the chopping blade and the light-emitting diode chip is 45-55 μm; during splitting, the chopping blade presses against the light-emitting diode chip for 15-25 ms.

[0115] Here, the distance between the cutting tool and the LED chip is set at 45–55 μm. This distance is neither too large, which would affect the cutting efficiency, nor too small, which would make the chip easily damaged by bumps. This achieves a balance between risk and efficiency.

[0116] In this implementation, the cutting blade presses against the LED chip for 15-25 ms, a time that is neither too long nor too short, ensuring the cutting effect while avoiding damage to the LED chip.

[0117] For example, before splitting the wafer, the distance between the chopping blade and the LED chip is 50 μm; during splitting, the chopping blade presses against the LED chip for 20 ms.

[0118] In this embodiment of the disclosure, step S24 may include:

[0119] The cleaving is performed along the direction from the edge of the LED chip toward the center, with priority given to cleaving the oblique surface of the sapphire substrate.

[0120] The above method refers to splitting the oblique crack surface on the slicing path first, from the edge to the center, after determining the slicing path. After the oblique crack surface is split, the non-oblique crack surface on the slicing path is split from the edge to the center.

[0121] Among them, the oblique crack surface and the non-oblique crack surface can be recorded in advance during the laser scribing process.

[0122] In addition, during the above-mentioned cleaving process, the cleaving method used was frontal cleaving, and the cleaving direction was longitudinal cleaving.

[0123] Cleaving refers to splitting the LED from the front side with electrodes. During cleaving, the cleaver strikes down, then rises and moves to the next position, repeating the process. Therefore, the cleaving path can be planned. In this embodiment, cleaving proceeds from the edge of the LED chip towards the center, with the oblique cleaving surface cleaved first, followed by the non-oblique cleaving surface. This makes the non-oblique cleaving surface easier to cleave and prevents the un-cleaved oblique cleaving surface from breaking apart and deforming during cleaving, thus avoiding affecting the cleaving effect. Furthermore, experimental verification has shown that this approach yields the best cleaving effect.

[0124] The hammering force used in the splitting process can be verified in advance through testing, for example, by observing the DBR back-crushing on the back of the product after splitting. Figure 3 Large-area back collapses and rubber strands are prohibited. Figure 4 If the following abnormalities exist, the hammering force needs to be re-optimized.

[0125] S25: Attach the second blue film to the metal ring.

[0126] For example, the metal ring is an iron ring.

[0127] The size of the iron ring is 260mm.

[0128] In this embodiment of the disclosure, the viscosity of the second blue film is greater than or equal to 0.4, and the diameter of the second blue film is 255-260 mm.

[0129] For example, the diameter of the second blue film is 258 mm. Although the blue film is smaller than the iron ring, it can adhere to most of the iron ring without affecting the use of the blue film.

[0130] S26: After the dicing is completed, the light-emitting diode chip is attached to the second blue film of the metal ring and pressed.

[0131] This is the side of the LED chip that is not covered by the first blue film.

[0132] In this embodiment of the disclosure, during tableting, the tableting time is 8 to 12 seconds and the tableting pressure is less than or equal to -0.6 MPa.

[0133] In this implementation, the aforementioned pressing time and pressure can ensure the pressing effect while avoiding damage to the LED chip.

[0134] For example, during tableting, the tableting time is 10 seconds and the tableting pressure is less than or equal to -0.6 MPa.

[0135] S27: Place one side of the light-emitting diode chip on a nano vacuum disk for adsorption, and remove the first blue film.

[0136] This is where the LED chip is attached to the side with the second blue film.

[0137] After placing one side of the LED chip on the nano vacuum disk for adsorption, the first blue film can be peeled off.

[0138] In this embodiment of the disclosure, after step S27 is performed, the third blue film can be reattached and then peeled off, and this process can be repeated twice. By attaching and peeling off the blue film, it is easier to detect problems such as electrodes lifting up during scratches.

[0139] S28: Expand the second blue film to separate the light-emitting diode chip after cleaving.

[0140] In the above steps, the light-emitting diode chip is separated after being cleaved by pressing and expanding the film.

[0141] In this embodiment of the disclosure, the second blue film is expanded by 120±2 mm.

[0142] In this embodiment of the disclosure, the diameter of the entire light-emitting diode wafer before cleaving is 105 mm, and the diameter of the region formed by multiple chips after film expansion is 120 ± 2 mm, so that the multiple chips are fully separated.

[0143] S29: Place the expanded film of the light-emitting diode chip on an optical display mirror for inclined plate inspection to observe the lifting of the electrodes at the edge of the light-emitting diode chip.

[0144] The inclined plate test refers to the process of using an inclined plate to support the light-emitting diode chip during observation, making it easier for the optical display lens to observe the lifting of the electrodes of the light-emitting diode chip.

[0145] After each scratching procedure is completed, the technicians place the expanded film product on an optical display mirror for inclined plate inspection to observe whether the electrode edges are raised. Once it is confirmed that there are no raised electrodes, the product can be delivered for mass production.

[0146] After the above improvements, the problem of electrodes being suspended and tilted due to sapphire defects on the side of the chip can be largely eliminated.

[0147] After the above improvements, the appearance yield increased by 0.83%, the electrical yield increased by 1.26%, and the overall yield increased by 2.09%. The data before and after the improvement are shown in Table 1 below:

[0148] Table 1

[0149]

[0150] VF2 represents the chip's turn-on voltage.

[0151] In other words, the cleaving scheme provided in this disclosure has been experimentally verified, demonstrating that the adopted scheme and its parameters can improve the appearance and electrical yield of the upright LED chip after cleaving.

[0152] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for slicing, characterized in that, The method is applicable to upright light-emitting diode chips with a sapphire substrate, and the method includes: A first blue film is attached to the side of the light-emitting diode chip away from the sapphire substrate, and the thickness of the upright light-emitting diode chip is not less than 200 micrometers; A dual-focus laser is used to scribe the other side of the LED chip. During the scribe process, the distance between the two focal points of the laser emitted by the dual-focus laser within the LED chip is controlled to be 25–30 μm, the dot spacing of the non-cleft surfaces of the sapphire substrate is controlled to be 5–7 μm, and the dot spacing of the cleft surfaces of the sapphire substrate is controlled to be 9–10 μm. The parameters, emission angle, and power of the dual-focus laser are controlled so that the line fluctuation range of the laser irradiation on the LED chip is -2 μm to 2 μm. The dicing process is used to cleave the diced LED chip.

2. The method according to claim 1, characterized in that, The method further includes: Before dicing, the parameters of the dual-focus laser, the output angle of the dual-focus laser, and the power of the dual-focus laser are determined as follows: Using a U-FAST dual-focus laser, with the explosion effect and line straightness as optimization targets, the parameters of the U-FAST dual-focus laser are adjusted in steps to obtain the first laser parameter value. The parameters of the U-FAST dual-focus laser include DW0, DW1 and PK26PA values. When using the first laser parameter value as the parameter of the U-FAST dual-focus laser, the line deviation is used as the optimization target, and the output angle of the U-FAST dual-focus laser is adjusted in steps to obtain the first laser output angle. The output angle of the U-FAST dual-focus laser includes the non-oblique crack surface output angle and the oblique crack surface output angle. Using the first laser parameter value as the parameter of the U-FAST dual-focus laser and the first laser output angle as the output angle of the U-FAST dual-focus laser, the power of the U-FAST dual-focus laser is adjusted in steps with the line fluctuation range as the optimization target to obtain the first laser power. The first laser parameter values, the first laser emission angle, and the first laser power are the parameters of the dual-focus laser used during dicing, the emission angle of the dual-focus laser, and the power of the dual-focus laser.

3. The method according to claim 2, characterized in that, The values ​​of DW0, DW1, and PK26PA are 15-20, 15-20, and 8-9, respectively. The light emission angles of the non-oblique crack surface and the oblique crack surface are 55° and 84°, respectively.

4. The method according to any one of claims 1 to 3, characterized in that, A blue film is attached to one side of the light-emitting diode chip, including: The light-emitting diode chip is placed on a base with nano-vacuum holes and adsorbed under vacuum with an adsorption pressure of less than or equal to -80 kPa. In the adsorption state, the first blue film is attached to one side of the light-emitting diode chip. The viscosity of the first blue film is less than or equal to 0.3N / 20mm, and the diameter of the first blue film is 255-260mm.

5. The method according to any one of claims 1 to 3, characterized in that, During the dicing process, the laser frequency on the non-cleft surface of the sapphire substrate is 90-110 Hz, and the dicing speed is 450-630 mm / s; the laser frequency on the cleft surface of the sapphire substrate is 45-55 Hz, and the dicing speed is 450-550 mm / s.

6. The method according to any one of claims 1 to 3, characterized in that, The process of cleaving the diced LED chip using a cleaver includes: The slit is made along the direction from the edge of the light-emitting diode chip toward the center, and the oblique surface of the sapphire substrate is slit preferentially.

7. The method according to any one of claims 1 to 3, characterized in that, During the chip splitting process, the spacing between the LED chips is 2-3 μm under the chip splitting debugging conditions.

8. The method according to any one of claims 1 to 3, characterized in that, The method further includes: Attach the second blue film to the metal ring; After the dicing is completed, the light-emitting diode chip is attached to the second blue film of the metal ring and pressed. One side of the light-emitting diode chip is placed on a nano vacuum disk for adsorption, and the first blue film is removed. The second blue film is expanded to separate the light-emitting diode chip after cleaving.

9. The method according to claim 8, characterized in that, During tableting, the tableting time is 8 to 12 seconds, and the tableting pressure is less than or equal to -0.6 MPa.

10. The method according to claim 8, characterized in that, The method further includes: The expanded film of the light-emitting diode chip is placed on an optical display mirror for inclined plate inspection to observe the lifting of the electrodes at the edge of the light-emitting diode chip.

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