A laser lift-off method and laser lift-off apparatus

Abstract

The application discloses a laser stripping method and a laser stripping device. The laser stripping method comprises the following steps: emitting laser from the side of the carrier glass away from the sacrificial layer, so that the laser is obliquely incident into the carrier glass at an angle inclined to the surface of the carrier glass, so that the sacrificial layer absorbs laser energy and is thermally decomposed; the peeling area of the flexible panel is scanned by multiple laser scans at the oblique incidence angle, the laser energy density of adjacent two laser scans is distributed in a gradient decreasing manner, the path of the latter laser scan is staggered from the path of the former laser scan by a preset distance in the direction perpendicular to the scanning travel direction, and the preset distance is smaller than the width of the laser spot. Through the above method, the laser stripping method provided by the application greatly improves the laser energy utilization rate, avoids damaging the flexible substrate, and greatly improves the peeling yield.

Description

Technical Field

[0001] This application relates to the field of flexible display panel manufacturing technology, and in particular to a laser peeling method and laser peeling device. Background Technology

[0002] As flexible display technology advances towards higher generation lines (≥8th generation), the demand for mass production of ultra-thin PI flexible substrates and UTG ultra-thin glass composite flexible panels is increasing dramatically. Laser lift-off (LLO) is a core technology for achieving precise separation between the flexible substrate and the rigid carrier glass. Its core principle is to use a specific wavelength laser to irradiate the carrier glass side, causing the sacrificial layer between the flexible substrate and the carrier glass to precisely absorb the laser energy and undergo thermal decomposition. The generated gas, through expansion force, pushes the flexible substrate and carrier glass to achieve damage-free separation.

[0003] However, existing laser stripping processes have the following drawbacks: 1) Low energy utilization and easy damage to functional layers due to vertical laser incidence. Existing processes mostly use vertically incident laser scanning, which causes the laser to reflect at the interface between the carrier glass and the sacrificial layer, resulting in a laser energy utilization rate of only about 60%. At the same time, the reflected light can burn the functional layer on the front side of the flexible substrate, producing defects such as black spots and bright spots, which cannot meet the high-quality requirements of high-generation line panels. 2) Uneven stripping in a single scan and easy to cause substrate defects. The concentrated energy distribution in a single scan can easily lead to uneven decomposition of the sacrificial layer. Insufficient gas generation in some areas results in incomplete stripping, while excessive energy in some areas causes heat accumulation, leading to warping and edge cracking of the flexible substrate, which seriously affects product yield. 3) Low yield of large-size panels in high-generation lines. For large-size (≥8th generation) flexible panels, due to the difficulty in controlling energy at a single point and the amplification of heat accumulation effect, the stripping yield of a single vertical scan is only about 85%, which cannot meet the yield requirements of large-scale mass production in high-generation lines. Currently, the industry only adjusts the incident angle or the number of scans, without forming a systematic matching solution, which cannot solve the above-mentioned core technical problems at the same time. Summary of the Invention

[0004] This application provides a laser peeling method and a laser peeling apparatus to solve the problems of low energy utilization, easy damage to the substrate, and low yield in the current laser peeling process for flexible panels in high-generation lines.

[0005] To address the aforementioned technical problems, this application provides a laser peeling method. This laser peeling method is used to separate the flexible substrate of a flexible panel from a carrier glass. The flexible panel includes a flexible substrate, a sacrificial layer, and a carrier glass stacked sequentially. The laser peeling method includes: emitting a laser from the side of the carrier glass away from the sacrificial layer, causing the laser to obliquely enter the carrier glass at an angle inclined to the surface of the carrier glass, so that the sacrificial layer absorbs laser energy and undergoes thermal decomposition; performing multiple laser scans on the peeling area of ​​the flexible panel using the oblique angle of incidence, with the laser energy density of adjacent laser scans decreasing in a gradient distribution, and the path of the subsequent laser scan being offset from the path of the previous laser scan by a predetermined distance perpendicular to the scanning direction, the predetermined distance being less than the width of the laser spot.

[0006] In some embodiments, the angle between the incident direction of the laser and the horizontal plane of the carrier glass is 40°–70°.

[0007] In some embodiments, during the multiple laser scans of the peeled area of ​​the flexible panel using the oblique incidence angle, the peeled area is scanned 3–5 times, and the laser energy density of the first laser scan is 280–350 mJ / cm².

[0008] In some embodiments, the laser energy density of each subsequent laser scan is reduced by 50–80 mJ / cm² compared to the previous scan, and the laser energy density of the final laser scan is 80–120 mJ / cm².

[0009] In some embodiments, the multiple laser scans all employ a serpentine scanning path, and the preset distance is 1 / 3–2 / 3 of the laser spot width.

[0010] In some embodiments, the scanning parameters of the laser scanning include: a laser spot width of 200–400 μm, a laser scanning speed of 50–300 mm / s, and a laser pulse frequency of 50–600 Hz.

[0011] In some embodiments, after performing multiple laser scans on the peeled area of ​​the flexible panel using the oblique incidence angle, the method further includes: Visual inspection is used to perform full-area detection of the separation gap between the flexible substrate and the carrier glass. If the separation gap size at each location is greater than or equal to a preset size threshold, the peeling is determined to be complete, and inert gas is used to purge and remove the residue at the peeling interface.

[0012] In some embodiments, after performing full-area detection of the separation gap between the flexible substrate and the carrier glass using visual inspection, the method further includes: If a local unseparated area is detected, a single scan is performed on the local unseparated area, and the separation gap is detected again until the separation is determined to be complete.

[0013] In some embodiments, the laser energy density for a single scan of the locally unseparated region is 100–150 mJ / cm².

[0014] To solve the above-mentioned technical problems, another technical solution adopted in this application is: to provide a laser ablation device. This laser ablation device, applying the laser ablation method as described above, is characterized by comprising: Laser emitting module, used to emit laser light; An angle adjustment module, connected to the laser emitting module, is used to adjust the incident direction of the laser so that the laser is incident at an angle inclined to the surface of the carrier glass. A mobile support module is used to support the flexible panel and can drive the flexible panel to move relative to the laser emitting module; A control module, electrically connected to the laser emitting module, the angle adjustment module, and the carrier moving module, is used to control the energy output of the laser emitting module and the movement trajectory of the carrier moving module to perform multiple laser scans on the peeled area of ​​the flexible panel.

[0015] The beneficial effects of this application are as follows: Unlike existing technologies, this application discloses a laser peeling method and a laser peeling apparatus. In this embodiment, by incidenting the laser at an angle of 40°–70° into the carrier glass, the reflectivity of the laser at the interface between the carrier glass and the sacrificial layer is effectively reduced, greatly improving the laser energy utilization rate. Simultaneously, it avoids burn defects caused by reflected light directly hitting the flexible functional layer of the flexible panel. Furthermore, by employing multiple laser scans with progressively decreasing energy, the first high-energy scan achieves deep decomposition of the sacrificial layer, while subsequent low-energy scans achieve shallow and uniform decomposition, avoiding the heat accumulation problem of a single high-energy scan, ensuring a consistent peeling gap, and solving the problem of warping and cracking of the flexible substrate. In addition, by offsetting the subsequent scan path from the previous scan by a preset distance less than the spot width, the energy weakness area at the edge of the spot is eliminated, significantly improving the peeling yield for large-size ≥8th generation high-generation flexible panels. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic flowchart of an embodiment of the laser ablation method provided in this application; Figure 2 This is a schematic diagram of the flexible panel structure; Figure 3 This is a schematic diagram of an embodiment of the laser ablation device provided in this application. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0018] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] This application provides a laser ablation method, see reference. Figure 1 and Figure 2 , Figure 1 This is a schematic flowchart of an embodiment of the laser ablation method provided in this application. Figure 2 This is a schematic diagram of the flexible panel structure.

[0021] The laser lift-off method is used to separate the flexible substrate 202 of the flexible panel 200 from the carrier glass 204. The flexible panel 200 includes a flexible functional layer 201, a flexible substrate 202, a sacrificial layer 203 and a rigid carrier glass 204 stacked in sequence. The flexible substrate 202 can be made of polyimide (PI) or ultra-thin flexible glass (UTG), and the sacrificial layer can be a SiO2 layer or an organic resin layer.

[0022] During the manufacturing process of the flexible panel 200, after the functional layer is prepared on the carrier glass 204, the flexible substrate 202 and the carrier glass 204 are separated without damage.

[0023] The laser ablation method includes: Step 10: Emit a laser from the side of the carrier glass away from the sacrificial layer, so that the laser is obliquely incident into the carrier glass at an angle tilted to the surface of the carrier glass, so that the sacrificial layer absorbs the laser energy and undergoes thermal decomposition.

[0024] In the prior art, vertically incident lasers are prone to strong reflection at the interface between the carrier glass 204 and the sacrificial layer 203, which not only leads to low laser energy utilization, but also causes the reflected light to directly hit the flexible functional layer 201 and burn the flexible functional layer 201.

[0025] like Figure 2 As shown, when the obliquely incident laser beam enters the carrier glass 204 at a certain angle and reaches the interface of the sacrificial layer 203, the reflected light is deflected to the side and upward due to the change in the incident angle, and is no longer reflected back to the flexible functional layer 201 perpendicularly. Thus, while causing the sacrificial layer 203 to absorb heat and decompose, the physical conditions for the flexible functional layer 203 to be burned are fundamentally eliminated.

[0026] In this embodiment, the angle α between the incident direction of the laser and the horizontal plane of the carrier glass 204 is 40°–70°. The specific value of the angle α between the incident direction of the laser and the horizontal plane of the carrier glass 204 can be flexibly selected according to the thickness and refractive index of the carrier glass 204.

[0027] Specifically, the angle α between the incident direction of the laser and the horizontal plane of the carrier glass 204 can be 40°, 45°, 50°, 55°, 60°, 65° or 70°, etc.

[0028] When the included angle α is set to 40°, the oblique optical path of the laser in the carrier glass 204 is relatively short, which is suitable for ultra-thin flexible substrates (such as PI with a thickness ≤30μm) that are extremely sensitive to heat accumulation. This angle can ensure that the reflected light deviates from the flexible functional layer 203 and minimize the transmission attenuation of the laser in the carrier glass 204.

[0029] When the included angle α is set to 55°, after optical tracing calculation, the reflected light path is guided to the side of the carrier glass 204 for maximum dissipation, completely eliminating stray light. Moreover, the combined indicators of laser transmittance and focus quality are better at this angle, making it particularly suitable for the batch peeling process of large-size ≥8th generation high-generation flexible panels.

[0030] When the included angle α is set to 70°, the laser enters the carrier glass 204 in a grazing posture. At this angle, the projection of the light spot on the horizontal plane is elongated, which is suitable for specific process scenarios that require expanding the width of a single scan. However, it is necessary to use a glass material with high transmittance to overcome the slight energy loss caused by the long optical path.

[0031] If the angle α is greater than 70°, the optical path characteristics are close to perpendicular incidence, the reflected light deflection amplitude is insufficient, and the laser is prone to reflection at the interface between the carrier glass 204 and the sacrificial layer 203, which not only reduces the laser energy utilization rate, but also poses a risk of burning the flexible functional layer 201. If the incident angle is less than 40°, the incident area of ​​the laser on the surface of the carrier glass 204 increases sharply, resulting in severe elliptical distortion of the laser spot and a significant decrease in energy density, which cannot meet the laser energy threshold requirements for the decomposition of the sacrificial layer 203.

[0032] Therefore, this embodiment strictly limits the included angle α to the range of 40°–70°, changes the reflection path of the reflected light to cause it to dissipate on the side, effectively reduces the interface reflectivity, and greatly improves the laser energy utilization rate to over 90%. It completely eliminates the appearance defects such as black spots and bright spots on the front of the flexible panel that are easily caused during laser peeling, and is extremely suitable for the high-quality processing requirements of high-generation flexible panels.

[0033] Furthermore, this laser ablation method can also incorporate a spatial light modulator (SLM) for beam shaping. Since the optical path changes when the laser is obliquely incident through the carrier glass 204 compared to perpendicular incident, it may introduce slight astigmatism or focus shift. By placing a spatial light modulator in the optical path, phase compensation of the laser wavefront can be performed in real time, dynamically correcting the optical path difference caused by oblique incident. This ensures that the light spot focused inside the sacrificial layer 203 always remains circular and its energy is distributed in a flat-top shape, thereby further improving the consistency of the modified layer in the edge area of ​​large-size panels.

[0034] Step 20: Perform multiple laser scans on the peeled area of ​​the flexible panel using an oblique incidence angle, with the laser energy density of adjacent laser scans decreasing in a gradient, and the path of the subsequent laser scan being offset from the path of the previous laser scan by a preset distance perpendicular to the scanning direction, which is less than the width of the laser spot.

[0035] In existing laser stripping solutions, only a single high-energy laser scan is used to scan the stripping area of ​​the flexible panel 200, which can easily lead to heat accumulation, causing the sacrificial layer 203 to release decomposition gas violently, resulting in warping or edge cracking of the flexible substrate 202.

[0036] This embodiment performs multiple laser scans on the peeling area of ​​the flexible panel 200 and sets up an energy gradient reduction mechanism to ensure that the heat input of each laser scan is precisely matched with the staged decomposition kinetics of the sacrificial layer 203. This gradually releases decomposition gases and mitigates thermal stress, resulting in uniform thermal stress distribution throughout the separation process and avoiding thermal shock. This prevents warping or edge cracking of the flexible substrate 202. At the same time, through a path misalignment design, the laser scan spots of each scan form an interlaced coverage in space, resulting in more uniform spot coverage. This effectively eliminates local overheating and energy superposition blind spots, and also effectively avoids the problem of uneven peeling caused by energy attenuation at the edge of the spot in a single scan. This makes the stress distribution at the peeling interface highly uniform, ensuring the integrity and consistency of the peeling interface and greatly improving the peeling yield.

[0037] In this embodiment, when performing multiple laser scans on the peeling area of ​​the flexible panel 200 at an oblique incidence angle, the peeling area of ​​the flexible panel 200 is scanned 3-5 times. The laser energy density of the first laser scan is 280-350 mJ / cm², and the laser energy density of adjacent laser scans decreases in a gradient distribution. The first scan uses a high laser energy density to achieve deep decomposition of the sacrificial layer 203, and subsequent scans use a gradually increasing laser energy density to achieve shallow and uniform decomposition of the sacrificial layer 203. This avoids the heat accumulation problem caused by using a single high laser energy density scan, and ensures that the gas generated by the decomposition of the sacrificial layer 203 is released evenly and the peeling gap is consistent. This makes the peeling of the large-size flexible panel 200 of the high generation line more thorough and avoids warping and cracking of the flexible substrate 202.

[0038] Specifically, the peeled area of ​​the flexible panel 200 is subjected to 3, 4, or 5 laser scans. The laser energy density of the first laser scan can be 280 mJ / cm², 290 mJ / cm², 300 mJ / cm², or 310 mJ / cm². 2 For sacrificial layers 203 of different thicknesses and materials, the laser energy density and number of laser scans in the first pass can be adapted to achieve dynamic matching between energy input and material thermal response characteristics, thereby gradually releasing decomposition gases and mitigating thermal stress.

[0039] When the sacrificial layer 203 is a relatively thin SiO2 layer (e.g., 0.5 μm thick), three scans are sufficient to achieve thorough decomposition from the surface to the interior, balancing efficiency and yield.

[0040] When the sacrificial layer 203 is a relatively thick organic photoresist layer or amorphous carbon layer (thickness > 1 μm), the number of scan passes is increased to 4 or 5. Increasing the number of scan passes is not a simple repetition, but rather a way to distribute the total decomposition energy across more laser scan cycles, allowing the sacrificial layer 203 material to undergo the complete physical process of "preheating-main decomposition-venting-homogenization". This effectively avoids the internal stress accumulation caused by poor venting during rapid thermal decomposition of thick materials.

[0041] The laser energy density for the first laser scan is set to 280–350 mJ / cm², a range that precisely matches the thermal decomposition threshold of commonly used sacrificial layer materials in high-generation laser lines. If the first laser energy density is below 280 mJ / cm², it may fail to penetrate the bottom layer of sacrificial layer 203 in the first scan; if the first laser energy density is above 350 mJ / cm², the excess heat will be conducted to the flexible substrate 202 and the flexible functional layer 201, causing thermal damage.

[0042] In this embodiment, after the first laser scan, the laser energy density of each subsequent laser scan is reduced by 50–80 mJ / cm² compared to the previous scan, and the laser energy density of the last laser scan is 80–120 mJ / cm².

[0043] The gradient design, with each subsequent laser energy density reduction of 50–80 mJ / cm², aims to maintain the stability of the decomposition reaction. If the reduction is less than 50 mJ / cm², the thermal effects of adjacent laser scans will be too strong, negating the purpose of multiple scans; if the reduction is greater than 80 mJ / cm², the energy step difference between adjacent laser scans will be too large, easily inducing localized alternating hot and cold microcracks in the material. The final laser energy density is controlled at 80–120 mJ / cm², which precisely maintains the micro-expansion of residual gas in the decomposed pores, promoting the uniform opening of the separation gaps without generating new thermal decomposition.

[0044] For example, when the initial laser energy density is 350 mJ / cm² and a total of 5 scans are performed, the laser energy densities for each scan are 350, 290, 230, 170, and 110 mJ / cm², respectively. This ensures that the energy input for each laser scan is completed within the material's heat capacity threshold, avoiding a sudden increase in thermal stress and local carbonization, while also ensuring that the gas release rate and the expansion speed of the peeling interface are precisely synchronized.

[0045] For example, when the laser energy density of the first pass is 300 mJ / cm² and there are a total of 4 scans, the laser energy densities of each pass are 300, 240, 180 and 120 mJ / cm² respectively. The last pass uses a laser energy of 120 mJ / cm² to precisely match the residual bonding energy of the surface layer of the sacrificial layer 203, so as to achieve gentle dissociation of the peeling interface.

[0046] For example, when the first laser energy density is 280 mJ / cm² and there are three scans, the laser energy densities for each scan are 280, 220, and 120 mJ / cm², respectively. The last scan uses a laser energy of 120 mJ / cm² to precisely trigger the residual bonding energy on the surface of the sacrificial layer 203, ensuring that there is no residue or damage during the peeling process.

[0047] In this embodiment, the laser energy density of the first laser scan is set to 280–350 mJ / cm², and the laser energy density of each subsequent laser scan is reduced by 50–80 mJ / cm² compared to the previous scan, with the laser energy density of the final laser scan controlled at 80–120 mJ / cm². Under this mechanism, the high energy of the first scan can penetrate the carrier glass 204 to achieve deep and instantaneous decomposition of the sacrificial layer 203, breaking the main bonding force. The decreasing energy gradient of subsequent scans acts on the shallow residual sacrificial layer 203, achieving uniform decomposition. This gradient energy distribution from deep to shallow fundamentally eliminates local thermal stress concentration, allows for uniform release of decomposition gas, and ensures a high degree of consistency in the peeling gap.

[0048] In this embodiment, during multiple laser scans, the path of each subsequent laser scan is offset from the path of the previous laser scan by a predetermined distance perpendicular to the scanning direction. This predetermined distance is less than the width of the laser spot. This offset design causes the heat-affected zones of adjacent scan paths to partially overlap, forming a continuous and uniform heat treatment zone. This avoids heat treatment blind zones caused by overheating superposition or complete separation due to complete path overlap, thereby ensuring the continuity of the sacrificial layer 203 at the microscale and the integrity of the interface peeling.

[0049] The preset distance is less than the width of the laser spot, which can realize the spatial complementarity of the spots on adjacent scanning paths. That is, by utilizing the energy complementarity effect of the spots on adjacent scanning paths, the edge energy dead zone caused by the Gaussian distribution of the beam energy is completely eliminated, so as to ensure scanning uniformity.

[0050] Laser scanning can employ either a serpentine scanning path or a loop scanning path, both of which ensure complete scanning coverage. The serpentine path is suitable for elongated substrates, while the loop path is more suitable for square or rectangular substrates, balancing scanning efficiency and heat accumulation control.

[0051] In this embodiment, a serpentine scanning path is used for multiple laser scans. Compared with the traditional round-trip scanning path, the serpentine scanning path eliminates the acceleration and deceleration pauses during scanning reversal, ensuring that the energy density of the laser acting on the sacrificial layer 203 is absolutely uniform along the time axis.

[0052] Furthermore, the preset distance is 1 / 3 to 2 / 3 of the laser spot width. The preset distance by which the paths of the two consecutive laser scans are staggered can be 1 / 3, 1 / 2, or 2 / 3 of the laser spot width, among which 1 / 2 of the laser spot width can achieve the optimal overlap rate of the heat-affected zone.

[0053] Specifically, when the pre-set offset distance is less than 1 / 3 of the laser spot width, the energy overlap area between adjacent scanning paths is too large, leading to severe secondary damage due to thermal accumulation in the overlap area. When the pre-set offset distance is greater than 2 / 3 of the laser spot width, due to the extremely low energy at the spot edge, there may be a scanning blind zone that is not fully covered between the two scanning paths, resulting in filamentary connections after stripping and insufficient and incomplete stripping. Therefore, the offset ratio of 1 / 3 to 2 / 3 of the laser spot width is the golden range for achieving energy spatial homogenization.

[0054] Furthermore, the scanning parameters for each laser scan include: laser spot width of 200–400 μm, laser scanning speed of 50–300 mm / s, and laser pulse frequency of 50–600 Hz.

[0055] In some embodiments, the laser spot width is set to 200 μm, combined with a high scanning speed (e.g., 300 mm / s) and a high pulse frequency (e.g., 600 Hz), forming a processing mode of "small spot, high frequency, and fast movement". The single-point dwell time in this mode is extremely short and the heat-affected zone is extremely small, which is suitable for UTG ultra-thin glass flexible panels that are extremely sensitive to thermal stress.

[0056] In other embodiments, the laser spot width is set to 400 μm, combined with a lower scanning speed (e.g., 50 mm / s) and a lower pulse frequency (e.g., 50 Hz), forming a processing mode of "large spot, low frequency, and slow movement speed". The large spot provides a larger single-pass coverage area, the low frequency ensures sufficient single-pulse energy, and the slow movement speed ensures sufficient energy deposition. This mode is particularly suitable for the pre-peeling process of silicon carbide flexible panels with thicker sacrificial layer materials or higher decomposition thresholds.

[0057] This embodiment effectively avoids the thermal shock peaks and path gap defects of traditional reciprocating scanning by employing a serpentine scanning path and setting the distance between the two laser scanning paths at a preset distance of 1 / 3–2 / 3 of the laser spot width perpendicular to the scanning direction. This achieves dual homogenization of energy in both spatial and temporal dimensions, significantly improving the uniformity and integrity of the peeling interface. At the same time, with the assistance of specific laser scanning parameters, it achieves perfect splicing and complementarity of laser energy in space, eliminating energy blind spots and excessive overlap areas, and ensuring the overall uniformity of the peeling interface of large-size panels in high-generation lines.

[0058] Furthermore, in this laser stripping method, the gradient reduction strategy of laser energy density in multiple laser scans can be combined with feedback from real-time infrared thermal imaging to dynamically adjust the dwell time and spot overlap rate of each laser scan, enabling millisecond-level adaptive compensation of laser energy in the spatial distribution of the stripping interface, thereby further improving the uniformity of the thermal field and the stability of the gas escape path at the stripping interface.

[0059] Step 30: Use visual inspection to perform full-area detection of the separation gap between the flexible substrate and the carrier glass.

[0060] Step 40: If the separation gap size at each location is greater than or equal to the preset size threshold, the peeling is determined to be complete, and the residue at the peeling interface is removed by purging with inert gas.

[0061] Step 50: If a local unseparated area is detected, perform a single scan on the local unseparated area and repeat the detection of the separation gap until the separation is determined to be complete.

[0062] After multiple laser scans are completed, the side containing the flexible functional layer 201 and the flexible substrate 202 is fixed, and the carrier glass 20 hangs down naturally under its own gravity. The area of ​​the sacrificial layer 203 that has been decomposed by the laser will further open up under the action of gravity to form obvious gaps, while the undecomposed area remains tightly attached.

[0063] The hardware for visual inspection may include an area scan camera and a telecentric lens. The area scan camera and telecentric lens acquire images of the separation interface, and the image processing unit performs edge recognition and gap size calibration. When it is determined that the separation gaps at all points are uniform and greater than or equal to a preset size threshold, the separation is considered to have met the standard.

[0064] Specifically, the hardware constituting the visual inspection also includes an infrared backlight source. Due to the difference in light transmittance of the flexible panel 200, the infrared backlight can penetrate the carrier glass 204 and the flexible substrate 202, causing the separation gap between the carrier glass 204 and the flexible substrate 202 to appear as a high-contrast dark band in the image.

[0065] The width of the dark band is extracted by an image processing algorithm and compared with a preset size threshold, for example, a preset size threshold of 50 μm. If the width of the dark band across the entire region is ≥50 μm, it proves from a physical mechanism that the gas expansion force of the sacrificial layer 203 has completely overcome the interlayer van der Waals force.

[0066] It should be noted that the preset size threshold is not a fixed value. It can be dynamically set according to the thickness and material of the flexible substrate 202. For example, for ultra-thin UTG substrates, the threshold can be set to 30-50μm; for thicker PI substrates, the threshold can be set to 50-80μm.

[0067] Once the peeling is complete, inert gases such as argon and nitrogen are used to purge and remove thermal decomposition residues from the interface to prevent the residues from damaging the flexible substrate 202 during subsequent handling.

[0068] In this embodiment, inert gas purging is not only used for physical slag removal, but also has the function of assisting thermal management. For example, high-purity helium is used as the purging gas. Due to the extremely high thermal conductivity of helium, it can quickly remove the residual heat from the peeling interface while purging the residue, realizing "second-level quenching" of the flexible substrate. This effectively prevents the molecular chains of the flexible substrate 202 (especially PI material) from relaxing or changing orientation at high temperatures, thereby further locking the low warpage state of the panel.

[0069] In some embodiments, due to the large area of ​​the high-generation flexible panel 200, there may be localized unseparated areas caused by slight thickness fluctuations in the carrier glass 204 or uneven coating of the sacrificial layer 203. Visual inspection can identify and record the coordinates of these unseparated areas. The flexible substrate 200 or the laser head can be moved relative to these coordinates to precisely position the laser head above them for a single, targeted re-scan. After the re-scan is completed, the system automatically triggers a re-inspection procedure, forming a closed-loop control logic of detection-re-scanning-re-inspection, completely preventing defective products with incomplete separation from flowing into the next process.

[0070] Furthermore, during local laser re-scanning, the incident angle of the laser can be automatically fine-tuned according to the location of the unseparated area. For example, it can be dynamically deflected by ±2° based on the original angle α. This is because the unseparated area is often accompanied by local stress deformation. Fine-tuning the incident angle can compensate for the optical path deflection caused by the deformation, which greatly improves the success rate of re-scanning.

[0071] Furthermore, the laser energy density for a single scan of the unseparated area is 100–150 mJ / cm². Since the area surrounding the unseparated region is usually already in a state of peeled-off voids, if the laser energy density for the scan is too high, the intense shock wave and thermal radiation will penetrate the voids and directly act on the back of the flexible substrate 202, causing excessive thermal impact on the already peeled area of ​​the flexible substrate 202, and even irreversible ablation pits. If the scan energy is too low, it cannot cut off the undecomposed sacrificial layer. Therefore, 100–150 mJ / cm² is appropriate. 2 The energy range of the cleanup is just right to provide the critical energy required to cut the bonding force of the residual sacrificial layer 203, which can accurately remove the connection point without affecting the surrounding structure, and at the same time will not cause new thermal damage.

[0072] This embodiment, through a closed-loop process design of detection-re-re-inspection, can greatly improve the overall peeling yield and peeling stability of the high-generation flexible panel 200.

[0073] Based on this, this application also provides a laser ablation device 100, see reference. Figure 3 , Figure 3 This is a schematic diagram of an embodiment of the laser ablation device provided in this application.

[0074] The laser peeling device 100 employs the laser peeling method described above. The laser peeling device 100 includes a laser emitting module 10, an angle adjustment module 20, a carrier moving module 30, a vision inspection module 40, and a control module 50. The laser emitting module 10 emits a laser beam; the angle adjustment module 20 is connected to the laser emitting module 10 and adjusts the incident direction of the laser beam, causing it to be incident at an angle inclined to the surface of the carrier glass 204; the carrier moving module 30 carries the flexible panel 200 and can drive relative movement between the flexible panel 202 and the laser emitting module 10; the vision inspection module 40 is used to inspect the flexible substrate. The separation gap between 202 and the carrier glass 204 is detected over the entire area. The control module 50 is electrically connected to the laser emitting module 10, the angle adjustment module 20, the carrier moving module 30, and the vision inspection module 40. It is used to control the energy output of the laser emitting module 10 and the movement trajectory of the carrier moving module 30 to perform multiple laser scans on the peeling area of ​​the flexible panel 200. It is also used to acquire the separation gap image data collected by the vision inspection module 40 and determine whether the peeling is complete. When the peeling is not complete, it coordinates with the control laser emitting module 10 and the carrier moving module 30 to perform a single scan on the local unseparated area.

[0075] Optionally, the laser emitting module 10 uses an excimer laser (such as a 308nm wavelength), the angle adjustment module 20 includes a mirror group driven by a high-precision servo motor, the carrying and moving module 30 uses a marble air-floating platform to isolate external vibrations, the vision inspection module 40 uses a combination of an infrared backlight source, an area array camera and a telecentric lens, and the control module 50 uses an FPGA-based real-time motion controller to ensure that the switching of energy gradients and path misalignment can be synchronized at the microsecond level under high-speed scanning of 50-300mm / s.

[0076] Optionally, the laser lift-off device 200 may also include a temperature control module (not shown), which is fitted below the carrier moving module 30 for active temperature control of the flexible panel 200 during the intervals between multiple laser scans. Since there is an unavoidable time interval between multiple scans, the temperature of the carrier glass 204 will fluctuate with the environment. The temperature control module uses a semiconductor cooling chip to maintain the temperature of the carrier glass 204 at room temperature (e.g., 22±0.5℃), eliminating thermal drift of optical components and mismatch of material thermal expansion coefficients caused by temperature differences. This controls the focal length drift during multiple scans to the nanometer level, further improving the lift-off yield.

[0077] Optionally, the laser stripping device 100 also integrates a diffractive optical element (DOE) beam splitting module (not shown) in its optical path. For the high-generation ultra-large flexible panel 200, the control module 50 uses the DOE to split a single laser beam into multiple beams (such as a 2×2 array) sub-beams. Combined with the large-stroke movement of the carrier moving module 30, seamless parallel oblique incidence scanning of multiple regions is achieved, thereby multiplying the effective scanning area per unit time and improving the laser stripping efficiency.

[0078] Unlike existing technologies, this application discloses a laser peeling method and a laser peeling apparatus. In this embodiment, by incidenting the laser at an angle of 40°–70° into the carrier glass, the reflectivity of the laser at the interface between the carrier glass and the sacrificial layer is effectively reduced, increasing the laser energy utilization rate from 60% to over 90%. Simultaneously, it avoids burn defects caused by reflected light directly hitting the flexible functional layer of the flexible panel. Furthermore, by employing multiple laser scans with progressively decreasing energy, the first high-energy scan achieves deep decomposition of the sacrificial layer, while subsequent low-energy scans achieve shallow and uniform decomposition, avoiding the heat accumulation problem of a single high-energy scan, ensuring consistent peeling gaps, and solving the problem of warping and cracking of the flexible substrate. In addition, by offsetting the subsequent scan path from the previous scan by a preset distance less than the spot width, the energy weakness area at the edge of the spot is eliminated. Combined with online visual inspection and anomaly correction closed-loop process, this method can significantly improve peeling yield and mass production efficiency for large-size ≥8th generation high-generation flexible panels, demonstrating strong versatility.

[0079] The above descriptions are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application. The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

Claims

1. A laser lift-off method for separating a flexible substrate from a carrier glass of a flexible panel, the flexible panel comprising a flexible substrate, a sacrificial layer, and a carrier glass stacked sequentially, characterized in that, The laser ablation method includes: A laser is emitted from the side of the carrier glass away from the sacrificial layer, so that the laser is obliquely incident into the carrier glass at an angle inclined to the surface of the carrier glass, so that the sacrificial layer absorbs the laser energy and undergoes thermal decomposition; The flexible panel is subjected to multiple laser scans at the oblique incidence angle, and the laser energy density of adjacent laser scans decreases in a gradient manner. The path of the subsequent laser scan is offset from the path of the previous laser scan by a preset distance perpendicular to the scanning direction, and the preset distance is less than the width of the laser spot.

2. The laser ablation method according to claim 1, characterized in that, The angle between the incident direction of the laser and the horizontal plane of the carrier glass is 40°–70°.

3. The laser ablation method according to claim 1, characterized in that, In the process of performing multiple laser scans on the peeled area of ​​the flexible panel using the oblique incidence angle, the peeled area is scanned 3–5 times, and the laser energy density of the first laser scan is 280–350 mJ / cm².

4. The laser ablation method according to claim 3, characterized in that, The laser energy density of each subsequent laser scan is reduced by 50–80 mJ / cm² compared to the previous scan, and the laser energy density of the final laser scan is 80–120 mJ / cm².

5. The laser ablation method according to claim 1, characterized in that, The multiple laser scans all employ a serpentine scanning path, and the preset distance is 1 / 3–2 / 3 of the laser spot width.

6. The laser ablation method according to claim 5, characterized in that, The laser scanning parameters include: laser spot width of 200–400 μm, laser scanning speed of 50–300 mm / s, and laser pulse frequency of 50–600 Hz.

7. The laser ablation method according to claim 1, characterized in that, After performing multiple laser scans on the peeled area of ​​the flexible panel using the oblique incidence angle, the method further includes: Visual inspection is used to perform full-area detection of the separation gap between the flexible substrate and the carrier glass. If the separation gap size at each location is greater than or equal to a preset size threshold, the peeling is determined to be complete, and inert gas is used to purge and remove the residue at the peeling interface.

8. The laser ablation method according to claim 7, characterized in that, After performing full-area detection of the separation gap between the flexible substrate and the carrier glass using visual inspection, the method further includes: If a local unseparated area is detected, a single scan is performed on the local unseparated area, and the separation gap is detected again until the separation is determined to be complete.

9. The laser ablation method according to claim 8, characterized in that, The laser energy density for a single scan of the unseparated local area is 100–150 mJ / cm².

10. A laser ablation apparatus, employing the laser ablation method as described in any one of claims 1 to 9, characterized in that, include: Laser emitting module, used to emit laser light; An angle adjustment module, connected to the laser emitting module, is used to adjust the incident direction of the laser so that the laser is incident at an angle inclined to the surface of the carrier glass. A mobile support module is used to support the flexible panel and can drive the flexible panel to move relative to the laser emitting module; A visual inspection module is used to perform full-area detection of the separation gap between the flexible substrate and the carrier glass; A control module, electrically connected to the laser emitting module, the angle adjustment module, the visual inspection module, and the carrier-mounted moving module, is used to control the energy output of the laser emitting module and the movement trajectory of the carrier-mounted moving module to perform multiple laser scans on the peeled area of ​​the flexible panel.

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