Wafer slotting system and method based on laser beam shaping by spatial light modulator

Abstract

This invention relates to a wafer grooving system and method based on a spatial light modulator-shaped laser beam, comprising a laser, a controller, a spatial light modulator, an optical transmission system, a processing platform, and a rangefinder. The laser emitter emits a laser beam and inputs it into the optical transmission system. The controller controls the spatial light modulator to shape the laser beam in the optical transmission system, sequentially forming a first and second stripe-shaped spot on the wafer surface. These spots are then sequentially grooved on the wafer surface according to the same pre-defined grooving trajectory. This invention utilizes the spatial light modulator to adjust the spot size and sequentially form the first and second spots, which are then sequentially grooved on the wafer surface according to the same pre-defined grooving trajectory. This allows the second spot to remove residue from both sides of the groove formed by the first spot, improving grooving quality. Furthermore, the energy distribution of the second spot can be adjusted to modify the groove structure, offering the advantage of precisely modulating the grooving pattern.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser processing technology, and in particular to a wafer grooving system and method based on a spatial light modulator-shaped laser beam. Background Technology

[0002] The continuous shrinking of semiconductor device dimensions and the increasing integration of chips have led to a sharp increase in the connections between metal interconnect layers, the parasitic capacitance between multilayer wirings, and the resistance of metal wires. This results in a series of problems, such as RC delay and increased power consumption, which seriously affect chip performance. When device dimensions are smaller than 90nm, wafers must use Low-K materials (low-k dielectrics) to isolate and support the interconnects between different layers within the integrated circuit. Because Low-K materials have a low dielectric constant, they can effectively reduce the parasitic capacitance of metal interconnects, thereby improving chip stability and operating frequency. Therefore, Low-K technology is currently a key focus in integrated circuit development, especially in areas such as logic operations and memory.

[0003] The use of Low-K materials has also brought a series of problems. This is because the mechanical strength and adhesion properties of Low-K materials are lower than those of silicon dioxide. During the chip separation process, traditional cutting tools can cause Low-K materials to splatter and have poor appearance, such as chipping, cracks, passivation, and metal layer lifting, which seriously affect the product yield.

[0004] To address the problems associated with traditional cutting tools, the mainstream approach is to use laser grooving to remove the low-k and copper metal layers. Laser processing, due to its non-contact, high-precision, and widely applicable characteristics, has become an effective solution for wafer fabrication.

[0005] There are two common laser beam shaping methods: one is a mask + elliptical spot shaping system. The elliptical spot shaping system primarily shapes the original Gaussian energy distribution laser spot into an approximately flat-topped spot, and then uses the mask to adjust the spot width. The second method uses a DOE (diffractive optical element) to split the laser into multiple beams, which are then arranged at specific points to achieve the grooving effect using multiple Gaussian focused spots. However, both methods have significant drawbacks:

[0006] 1. The essence of laser processing of Low-k materials on wafers is to utilize a high-energy beam to generate localized high temperatures in a very short time, causing the metal layer and interlayer dielectric to rapidly melt, vaporize, and be jetted away, thereby achieving precise material removal. Therefore, during laser processing, residues generated from the evaporation and jetting of the Low-k interlayer dielectric and metal material on the wafer surface will adhere to the wafer surface, affecting the material yield and processing quality.

[0007] 2. Current shaping methods cannot adjust the energy distribution of the shaping spot, and therefore cannot adjust the groove structure of the groove after grooving in real time. Different wafer samples have different grooving requirements. For example, some wafer samples require a large bottom groove width after grooving to facilitate subsequent diamond wheel cutting, which requires a "U"-shaped groove. Other wafer samples require higher strength and require a "U"-shaped groove. Conventional shaping methods cannot meet these different needs.

[0008] In addition, in the laser grooving process, a water-soluble temporary protective film is usually applied beforehand to protect the Low-k dielectric layer from contaminant penetration. This film undergoes irreversible modification due to the high heat load during laser processing. Because of the thermochemical deformation of the water-soluble temporary film, the cleaning solution cannot penetrate it, resulting in the inability to remove the film and slag in subsequent cleaning processes. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a wafer grooving system and method based on a spatial light modulator shaping laser beam, which addresses the shortcomings of the prior art.

[0010] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a wafer grooving system based on a spatial light modulator shaping laser beam, comprising a laser, a controller, a spatial light modulator, an optical path transmission system, a processing platform, and a rangefinder;

[0011] The laser is used to emit a laser beam;

[0012] The controller is used to set the grooving trajectory, generate control commands based on the grooving trajectory and size and the slag height information fed back by the rangefinder, and send them to the spatial light modulator.

[0013] The spatial light modulator is disposed in the optical path transmission system and is used to shape the laser beam in the optical path transmission system according to the control command of the controller, and sequentially form a strip-shaped first light spot and a second light spot on the wafer surface, wherein the size of the first light spot is smaller than the size of the second light spot;

[0014] The optical transmission system is used to transmit the laser beam emitted and shaped by the laser to the processing platform;

[0015] The processing platform is used to clamp the wafer and adjust its position so that the first and second light spots of different sizes formed by the laser beam reaching the wafer surface will successively perform two grooving operations on the wafer surface according to the same set grooving trajectory. The first light spot forms a first groove after grooving the wafer surface, and the second light spot forms a second groove after grooving the first groove and the two sides of the wafer surface.

[0016] The rangefinder is used to scan the molten slag on both sides of the first groove opening and to feed back the acquired molten slag height information to the controller.

[0017] The beneficial effects of this invention are as follows: The wafer grooving system based on a spatial light modulator-shaped laser beam utilizes a spatial light modulator to adjust the size of the shaping spot, sequentially forming a first spot and a second spot. It achieves rapid switching between different shaping spot sizes within the same dicing path on the Low-k layer of the wafer surface. This allows the first and second spots to sequentially groove the wafer surface along the same pre-defined grooving trajectory. Thus, when the second spot grooves, it can precisely remove the slag on both sides of the first groove from the first spot's grooving, based on the slag height from the first grooving. This solves the problem of slag generation during Low-k layer processing on the wafer surface, achieving high-quality grooving. Furthermore, the energy distribution of the second spot can be adjusted to modify the groove structure, offering the advantage of precise modulation of the grooving pattern. The two-stage laser grooving disperses the laser energy, avoiding the high-temperature critical point that easily reaches the water-soluble temporary protective film during single-stage laser grooving, which causes irreversible modification. This facilitates the wetting of the cleaning solution, allowing for the removal of the water-soluble temporary protective film and slag after grooving.

[0018] Based on the above technical solution, the present invention can be further improved as follows:

[0019] Further: The optical path transmission system includes a beam expander and collimator, a polarizer, a lens, a switching mirror, a focusing lens, a focusing objective, and a laser spot analyzer. The laser beam emitted from the laser sequentially enters the beam expander and collimator and the polarizer before being incident on the spatial light modulator. After being shaped by the spatial light modulator, the laser beam is incident on the lens. The switching mirror reflects the laser beam emitted from the lens to the laser spot analyzer or the focusing lens. The laser beam reflected to the focusing lens passes through the focusing objective and reaches the stage, forming a first and a second stripe-shaped spot on the wafer surface, so as to sequentially grooving the wafer surface according to the same set grooving trajectory.

[0020] The beneficial effects of the above-mentioned further scheme are as follows: the laser beam emitted from the laser can be expanded and collimated by the beam expanding and collimating element, then polarized by the polarizer and incident on the spatial light modulator. After being shaped and modulated, the laser beam is incident on the lens for focusing, and then reflected by the mirror to the laser spot analyzer or the focusing lens. The laser spot analyzer can analyze the spot parameters. The laser beam incident on the focusing lens is focused and then emitted, reaching the worktable, forming a strip-shaped first spot and a second spot on the wafer surface, thereby realizing the grooving processing of the Low-k layer on the wafer surface.

[0021] Further: The controller generates control commands based on the slotting trajectory and dimensions, as well as the slag height information fed back by the rangefinder, specifically as follows:

[0022] The controller determines the closed-loop energy distribution corresponding to the first light spot based on the slotting trajectory and size, generates a first control command, and sends it to the spatial light modulator.

[0023] The controller determines the closed-loop energy distribution corresponding to the second light spot based on the slotting trajectory and size, as well as the slag height information fed back by the rangefinder, generates a second control command, and sends it to the spatial light modulator.

[0024] The beneficial effects of the above-mentioned further scheme are: control commands for the first slotting can be accurately generated by the slotting trajectory and size, and the closed-loop energy distribution corresponding to the second spot can be accurately determined by the slag height fed back by the rangefinder during the second slotting, thereby accurately obtaining the corresponding second spot.

[0025] Further: The spatial light modulator shapes the laser beam and sequentially forms a first spot and a second spot on the wafer surface, so that the first spot and the second spot formed by the laser beam on the wafer surface sequentially groove the wafer surface according to the same preset grooving trajectory. Specifically, this includes the following steps:

[0026] The spatial light modulator shapes the laser beam according to the first control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped first light spot on the wafer surface, so as to groove the Low-k layer on the wafer surface according to the set grooving trajectory to form a first groove.

[0027] The spatial light modulator shapes the laser beam according to the second control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped second light spot on the wafer surface. This allows for grooving of the Low-k layer on the wafer surface according to the same set grooving trajectory, removing the slag on both sides of the first groove opening, and forming the second groove.

[0028] The width of the second light spot is greater than the width of the first light spot, and the first groove is located within the second groove.

[0029] The beneficial effects of the above-mentioned further solution are as follows: A first strip-shaped spot is formed on the wafer surface by a laser beam, and a groove is created on the Low-k layer of the wafer surface according to a set grooving trajectory, forming a first groove and obtaining the main structure of the groove. Then, a wider second strip-shaped spot is formed on the wafer surface by a laser beam, and the same grooving trajectory is used to groove the Low-k layer of the wafer surface. This removes the slag on both sides of the first groove opening. Simultaneously, the specific shape of the groove is precisely controlled by controlling the energy distribution of the second spot through the spatial light modulator. This not only improves the grooving quality but also allows for control of the grooving precision according to different application scenarios, thus meeting the grooving processing requirements of different wafers.

[0030] Furthermore, the width of the second light spot is at least 5 μm greater than the width of the first light spot.

[0031] The beneficial effect of the above-mentioned further scheme is that by controlling the width of the second spot and the first spot, the slag generated during the grooving process can be reduced as much as possible, while the grooving efficiency can be improved as much as possible.

[0032] Furthermore, the energy ratio of the second light spot to the first light spot is 0.4-0.6.

[0033] The beneficial effects of the above-mentioned further solution are: by adjusting the energy of the second light spot and the first light spot, the efficiency of grooving can be improved. At the same time, the slag on both sides of the first groove opening can be removed by the second light spot during grooving, without generating a lot of new slag, which greatly improves the grooving quality.

[0034] Furthermore, the energy distribution of the first light spot is uniform, while the energy distribution of the second light spot is high at both ends and low in the middle.

[0035] The beneficial effects of the above-mentioned further solution are as follows: by setting the energy distribution of the first light spot to a uniform distribution state, the required groove structure can be processed on the predetermined grooving trajectory of the wafer, so that the first light spot forms the main structure of the required groove on the wafer pre-cut track. By setting the energy distribution of the second light spot to a distribution state with high energy at both ends and low energy in the middle, when processing the first groove structure formed by the first light spot, the residue on both sides of the groove can be effectively removed by using the second light spot with high energy at both ends. While increasing the groove width, the shape of the groove can be precisely controlled by controlling the proportion of the energy at both ends of the second shaping light spot to the overall energy.

[0036] Furthermore, the energy at both ends of the second light spot accounts for 20%-50% of the total light spot energy.

[0037] The present invention also provides a wafer grooving method based on a spatial light modulator-shaped laser beam, which employs the aforementioned wafer grooving system based on a spatial light modulator-shaped laser beam and includes the following steps:

[0038] The laser emitter emits a laser beam, which is then input into the optical transmission system.

[0039] The controller generates a first control command for the spatial light modulator based on the set slotting trajectory and size, and sends it to the spatial light modulator.

[0040] The spatial light modulator, located in the optical transmission system, shapes the laser beam in the optical transmission system according to the first control command of the controller.

[0041] The optical transmission system transmits the laser beam emitted and shaped from the laser to the processing platform;

[0042] The processing platform clamps the wafer and adjusts its position so that the first spot formed by the laser beam reaches the wafer surface and grooves the wafer surface according to the set grooving trajectory, forming the first groove.

[0043] The rangefinder scans the molten slag on both sides of the first groove opening and feeds back the obtained molten slag height to the controller;

[0044] The controller generates a second control command based on the slotting trajectory and size, as well as the slag height information fed back by the rangefinder, and sends it to the spatial light modulator.

[0045] The spatial light modulator, located in the optical transmission system, shapes the laser beam in the optical transmission system according to the second control command of the controller.

[0046] The optical path transmission system transmits the laser beam emitted and shaped by the laser to the processing platform, so that the second spot formed by the laser beam reaches the wafer surface and grooves the first groove and both sides of the wafer surface according to the same grooving trajectory, forming the second groove; wherein the size of the first spot is smaller than the size of the second spot, and the first groove is located in the second groove.

[0047] Based on the above technical solution, the present invention can be further improved as follows:

[0048] Further: The spatial light modulator shapes the laser beam in the optical path transmission system and sequentially forms a first and a second stripe-shaped light spot on the wafer surface, so that the first and second light spots of different sizes formed by the laser beam on the wafer surface sequentially groove the wafer surface according to the same pre-set grooving trajectory. Specifically, this includes the following steps:

[0049] The spatial light modulator shapes the laser beam, and the output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped first light spot on the wafer surface, so as to groove the Low-k layer on the wafer surface according to the set grooving trajectory, forming a first groove.

[0050] The spatial light modulator shapes the laser beam, and the output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped second spot on the wafer surface. This spot is used to groove the Low-k layer on the wafer surface according to the same grooving trajectory, and removes the slag on both sides of the first groove opening to form the second groove.

[0051] The width of the second light spot is greater than the width of the first light spot, and the first groove is located within the second groove.

[0052] After the first groove is processed, the slag height data on both sides of the first groove is measured using a laser rangefinder on the equipment. This slag height data is fed back to a computer, where a specific software algorithm controls the energy distribution of the second laser spot to precisely control the slag produced by the first laser spot. Specifically, when the laser rangefinder reads a high slag height on both sides of the first groove, the energy of the second laser spot is increased to increase the amount of material processed on both sides of the second groove, thus removing the higher slag. Conversely, when the slag height on both sides of the first groove is low, the energy of the second laser spot is reduced to decrease the amount of material processed. This closed-loop slag removal method achieves dynamic and precise control of the slag at the groove opening.

[0053] The beneficial effects of the above-mentioned further solution are as follows: A first strip-shaped spot is formed on the wafer surface by a laser beam, and a groove is created on the Low-k layer of the wafer surface according to a set grooving trajectory, forming a first groove and obtaining the main structure of the groove. Then, a wider second strip-shaped spot is formed on the wafer surface by a laser beam, and the same grooving trajectory is used to groove the Low-k layer of the wafer surface. This removes the slag on both sides of the first groove opening. Simultaneously, the specific shape of the groove is precisely controlled by controlling the energy distribution of the second spot through the spatial light modulator. This not only improves the grooving quality but also allows for control of the grooving precision according to different application scenarios, thus meeting the grooving processing requirements of different wafers. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of a wafer grooving system based on a spatial light modulator-shaped laser beam according to an embodiment of the present invention;

[0055] Figure 2 This is the structure of a first light spot and a second light spot, as well as the corresponding first groove and second groove, according to an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the energy distribution of the first light spot according to an embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of the energy distribution of the second light spot according to an embodiment of the present invention;

[0058] Figure 5 This is the structure of a first light spot and a second light spot, and the corresponding first groove and second groove, according to another embodiment of the present invention;

[0059] Figure 6 This is a schematic flowchart of a wafer grooving method based on a spatial light modulator-shaped laser beam according to an embodiment of the present invention.

[0060] The attached diagram lists the components represented by each number as follows:

[0061] 1. Beam expander and collimator; 2. Polarizer; 3. Spatial light modulator; 4. Lens; 5. Switching mirror; 6. Focusing lens; 7. Focusing objective lens; 8. Processing platform. Detailed Implementation

[0062] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0063] This invention addresses the problem of slag adhesion on both sides of the groove after processing specific dicing paths on the wafer surface during laser grooving. It reduces slag accumulation by changing the width of the shaping laser spot during grooving. Specifically:

[0064] like Figure 1 As shown, a wafer grooving system based on a spatial light modulator-shaped laser beam includes a laser, a controller, a spatial light modulator, an optical path transmission system, a processing platform 8, and a rangefinder.

[0065] The laser is used to emit a laser beam;

[0066] The controller is used to set the grooving trajectory, generate control commands based on the grooving trajectory and size and the slag height information fed back by the rangefinder, and send them to the spatial light modulator.

[0067] The spatial light modulator 3 is disposed in the optical path transmission system and is used to shape the laser beam in the optical path transmission system according to the control command of the controller, and sequentially form a strip-shaped first light spot and a second light spot on the wafer surface, wherein the size of the first light spot is smaller than the size of the second light spot;

[0068] The optical path transmission system is used to transmit the laser beam emitted and shaped by the laser to the processing platform 8;

[0069] The processing platform 8 is used to clamp the wafer and adjust the position of the wafer so that the laser beam reaches the wafer surface and forms a first spot and a second spot of different sizes. The first spot and the second spot are then used to groove the wafer surface twice according to the same grooving trajectory. The first spot forms a first groove after grooving the wafer surface, and the second spot forms a second groove after grooving the first groove and the two sides of the wafer surface.

[0070] The rangefinder is used to scan the molten slag on both sides of the first groove opening and to feed back the acquired molten slag height information to the controller.

[0071] The wafer grooving system based on a spatial light modulator-shaped laser beam of the present invention utilizes a spatial light modulator to adjust the size of the shaping laser spot, sequentially forming a first spot and a second spot. It achieves rapid switching between different shaping spot sizes within the same dicing path on the Low-k layer of the wafer surface. This allows the first and second spots to sequentially groove the wafer surface along the same pre-defined grooving trajectory. Thus, when the second spot grooves, it can precisely remove the slag on both sides of the first groove from the first spot's grooving, based on the slag height from the first grooving. This solves the problem of slag generation during Low-k layer processing on the wafer surface, achieving a high-quality grooving effect. Furthermore, the structure of the groove can be adjusted by regulating the energy distribution of the second spot, offering the advantage of precisely modulating the grooving pattern. The two-stage laser grooving disperses the laser energy, avoiding the high-temperature critical point that easily reaches the water-soluble temporary protective film during single-stage laser grooving, which can lead to irreversible modification. This facilitates the wetting of the cleaning solution, allowing for the removal of the water-soluble temporary protective film and slag after grooving.

[0072] In one or more embodiments of the present invention, the optical path transmission system includes a beam expander and collimator 1, a polarizer 2, a lens 4, a switching mirror 5, a focusing lens 6, a focusing objective lens 7, and a laser spot analyzer 9. The laser beam emitted from the laser sequentially enters the beam expander and collimator 1 and the polarizer 2 and is then incident on the spatial light modulator 3. After being shaped by the spatial light modulator 3, the laser beam is incident on the lens 4. The switching mirror 5 reflects the laser beam emitted from the lens 4 to the laser spot analyzer 9 or the focusing lens 6. The laser beam reflected to the focusing lens 6 passes through the focusing objective lens 7 and reaches the stage 8, forming a first and a second stripe-shaped spot on the wafer surface in sequence, so as to sequentially grooving the wafer surface according to the same set grooving trajectory.

[0073] The laser beam emitted from the laser can be expanded and collimated by the beam expanding and collimating element 1, then polarized by the polarizer 2 and incident on the spatial light modulator 3. After being shaped and modulated, the laser beam is incident on the lens 4 for focusing, and then reflected by the mirror 5 to the laser spot analyzer 9 or the focusing lens 6. The laser spot analyzer 9 can analyze the spot parameters. The laser beam incident on the focusing lens 6 is focused and then emitted, reaching the stage 8, forming a strip-shaped first spot and a second spot on the wafer surface, thereby realizing the grooving process of the Low-k layer on the wafer surface.

[0074] For ease of adjustment, in this embodiment of the invention, the switching reflector 5 is electrically driven and can automatically switch between two angles, that is, the rotation angle of the switching reflector 5 can reflect the laser beam to the laser spot analyzer 9 or the focusing lens 6.

[0075] In one or more embodiments of the present invention, the controller generates control commands based on the slotting trajectory and dimensions, as well as the slag height information fed back by the rangefinder, specifically as follows:

[0076] The controller determines the closed-loop energy distribution corresponding to the first light spot based on the slotting trajectory and size, generates a first control command, and sends it to the spatial light modulator.

[0077] The controller determines the closed-loop energy distribution corresponding to the second light spot based on the slotting trajectory and size, as well as the slag height information fed back by the rangefinder, generates a second control command, and sends it to the spatial light modulator.

[0078] By using the grooving trajectory and dimensions, control commands for the first grooving can be precisely generated. Furthermore, during the second grooving, the closed-loop energy distribution corresponding to the second spot can be accurately determined by the slag height fed back by the rangefinder, thus accurately obtaining the corresponding second spot.

[0079] Specifically, such as Figure 2 As shown, in one or more embodiments of the present invention, the spatial light modulator 3 shapes the laser beam according to the first control command and sequentially forms a first light spot and a second light spot on the wafer surface, so that the first light spot and the second light spot formed by the laser beam reaching the wafer surface sequentially perform grooving on the wafer surface according to the same set grooving trajectory. The specific implementation is as follows:

[0080] The spatial light modulator 3 shapes the laser beam according to the second control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped first light spot on the wafer surface. This spot is then used to groove the Low-k layer on the wafer surface according to a set grooving trajectory, forming a first groove. Figure 2As shown in the upper left image, the blue stripe represents the first light spot, and the white stripe represents the first groove formed by the slotting.

[0081] In practice, a small-sized first light spot with relatively uniform energy is used to pre-process the pre-set dicing path on the wafer surface, forming a first groove on the pre-set dicing path. At this time, there are residues with a width of about 2-3 μm and a height of about 3 μm on both sides of the first groove on the pre-set dicing path, such as... Figure 2 As shown in the lower left image.

[0082] The spatial light modulator 3 shapes the laser beam, and the output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped second light spot on the wafer surface. This spot is used to groove the Low-k layer on the wafer surface according to the same pre-set grooving trajectory, removing the slag on both sides of the first groove opening and simultaneously forming the second groove. Figure 2 As shown in the upper right image, the blue stripe is the second light spot, and the white stripe is the second groove formed by the slotting.

[0083] Here, a laser beam with a second spot size (more than 5μm wider than the first spot) is used to perform a grooving process on the wafer surface for a predetermined cut. Since the slag on both sides of the first groove opening is removed, and the inner side of the groove opening is hollowed out during the formation of the second groove, only a very small amount of slag remains on the outer side, thus achieving the grooving effect while reducing slag at the groove opening and improving the grooving quality. Figure 2 As shown in the lower right image.

[0084] The width of the second light spot is greater than the width of the first light spot, and the first groove is located within the second groove.

[0085] After the first groove is processed, the slag height data on both sides of the first groove is detected by a rangefinder on the equipment. This slag height data is fed back to the controller. The controller uses a software algorithm to control the energy distribution of the second light spot, thereby precisely removing the slag generated during the processing of the first light spot. Specifically, when the rangefinder reads a high slag height on both sides of the first groove, the energy of the second light spot is increased to increase the amount of material processed on both sides of the second groove to remove the higher slag. When the energy of the second light spot on both sides of the first groove is low, the energy of the second light spot is reduced to reduce the amount of material processed on both sides of the second groove. This closed-loop slag removal method achieves dynamic and precise control of the slag at the opening of the first groove. Here, the rangefinder can be an existing Keyence rangefinder.

[0086] A laser beam forms a strip-shaped first spot on the wafer surface, grooving the Low-k layer along a predetermined grooving trajectory to form a first groove, thus obtaining the main structure of the groove. Then, a wider, strip-shaped second spot is formed on the wafer surface using the laser beam to groove the Low-k layer along the same grooving trajectory. This removes the slag on both sides of the first groove opening. Simultaneously, the energy distribution of the second spot is controlled by the spatial light modulator 3 to precisely control the specific shape of the groove. This not only improves the grooving quality but also allows for control of the grooving precision according to different application scenarios, meeting the grooving processing requirements of different wafers.

[0087] Optionally, in one or more embodiments of the present invention, the width of the second light spot is at least 5 μm greater than the width of the first light spot. By controlling the widths of the second and first light spots, the slag generated during the grooving process can be minimized while grooving efficiency can be maximized.

[0088] Optionally, in one or more embodiments of the present invention, the energy ratio of the second light spot to the first light spot is 0.4-0.6. By adjusting the energy of the second light spot and the first light spot, the efficiency of grooving can be improved. At the same time, the second light spot removes the slag on both sides of the first groove opening during grooving without generating a large amount of new slag, thus greatly improving the grooving quality.

[0089] like Figure 3 and Figure 4 As shown, in one or more embodiments of the present invention, Figure 3 In the first light spot, the energy distribution is uniform. Figure 4 In this process, the energy distribution of the second light spot is characterized by high energy at both ends and low energy in the middle. By setting the energy distribution of the first light spot to a uniform distribution, the required groove structure can be processed on the predetermined grooving trajectory of the wafer, allowing the first light spot to form the main structure of the required groove on the pre-cut track of the wafer. By setting the energy distribution of the second light spot to a distribution with high energy at both ends and low energy in the middle, the high-energy second light spot at both ends can effectively remove the residue on both sides of the groove. While increasing the groove width, the shape of the groove can be precisely controlled by controlling the proportion of energy at both ends of the second shaping light spot to the overall energy.

[0090] Optionally, in one or more embodiments of the present invention, the energy at both ends of the second light spot accounts for 20%-50% of the total light spot energy.

[0091] Since the first spot needs to process the required groove structure on the pre-cut track of the wafer, the energy distribution of the first spot is a nearly uniformly distributed shaping spot so that the first spot can form the main structure of the required groove on the pre-cut track of the wafer. Then, the second spot is used to modify the first groove structure in the first step. Specifically, the energy distribution of the second spot is high at both ends and low in the middle. During processing, the shaping spot with high energy at both ends can effectively remove the residue on both sides of the groove. While increasing the groove width, the shape of the second groove can be precisely controlled by controlling the proportion of the energy at both ends of the second spot to the overall energy.

[0092] Specifically, such as Figure 3 and Figure 4 The laser beam spot shown can be viewed in the spot analyzer. The energy at both ends of the second spot accounts for 20%-50% of the total spot energy, which allows for precise control of the groove shape being processed. When the energy at both ends accounts for 50% of the total energy, the desired "U"-shaped groove can be processed, such as... Figure 5 As shown on the left, this design improves the groove width ratio (the ratio of the lower groove width to the upper groove width), facilitating subsequent cutting by the cutting wheel. Alternatively, selecting an energy level where the energy at both ends accounts for 20% of the total energy can produce the desired "∪" shaped groove. Figure 5 As shown on the right, the junction between the bottom of the groove and the groove wall has a smooth arc transition, which avoids stress concentration and helps improve the chip strength.

[0093] This invention first uses a small first spot to pre-process a predetermined dicing path on a specific dicing path on the wafer surface. During the processing, slag will accumulate on both sides of the first groove. In the next step, a larger second spot is used to repeat the grooving process at the grooving position of the previous step. When grooving, the larger second spot will cover the groove processed by the previous smaller shaping spot and the slag on both sides. At this time, the larger second spot will melt and remove the pre-processed second groove and the slag at the groove opening at the same time, thereby achieving the effect of less slag at the groove opening and improving the grooving quality.

[0094] Meanwhile, to meet the specific process requirements of different wafer samples from customers, if there are specific requirements for the shape of the groove after grooving, such as a "U"-shaped or "U"-shaped groove, a spatial light modulator 3 is used to control the ratio of energy at both ends of the second shaping spot to the total energy, thereby controlling the shape of the second groove after grooving on a specific dicing track of the wafer. When the energy ratio at both ends of the second spot is higher, a "U"-shaped groove can be obtained; when the energy ratio on both sides of the shaping spot is lower, a "U"-shaped groove can be obtained.

[0095] This invention utilizes the spatial light modulator's ability to easily adjust the spot size, enabling rapid switching between different shaping spot sizes within the same dicing channel of the Low-k layer on the wafer surface. This solves the problem of slag generation during Low-k layer processing on the wafer surface. Furthermore, based on the spatial light modulator's ability to easily modulate the spot energy distribution, the groove structure is controlled to meet the grooving requirements of different wafers, thus achieving a high-quality grooving effect. Additionally, by controlling the energy levels at both ends of the second spot, the shape of the second groove after grooving is controlled, thereby achieving precise modulation of the grooving shape.

[0096] It should be noted that, in the embodiments of the present invention, more laser beams may be set, and strip-shaped light spots of different widths may be formed sequentially on the wafer surface, and grooving processing may be performed sequentially on the predetermined cutting channels on the wafer surface, forming grooves of a specific shape on the predetermined cutting channels on the wafer surface.

[0097] like Figure 6 As shown, the present invention also provides a wafer grooving method based on a spatial light modulator-shaped laser beam, which employs the aforementioned wafer grooving system based on a spatial light modulator-shaped laser beam and includes the following steps:

[0098] The laser emitter emits a laser beam, which is then input into the optical transmission system.

[0099] The controller generates a first control command for the spatial light modulator 3 based on the set slotting trajectory and size, and sends it to the spatial light modulator.

[0100] The spatial light modulator 3, installed in the optical path transmission system, shapes the laser beam in the optical path transmission system according to the first control command of the controller;

[0101] The optical transmission system transmits the laser beam emitted and shaped from the laser to the processing platform 8;

[0102] The processing platform 8 clamps the wafer and adjusts its position so that the first spot formed by the laser beam reaches the wafer surface and grooves the wafer surface according to the set grooving trajectory, forming the first groove.

[0103] The rangefinder scans the molten slag on both sides of the first groove opening and feeds back the obtained molten slag height to the controller;

[0104] The controller generates a second control command based on the slotting trajectory and size, as well as the slag height information fed back by the rangefinder, and sends it to the spatial light modulator.

[0105] The spatial light modulator 3, installed in the optical path transmission system, shapes the laser beam in the optical path transmission system according to the second control command of the controller;

[0106] The optical path transmission system transmits the laser beam emitted and shaped by the laser to the processing platform 8, so that the second spot formed by the laser beam reaches the wafer surface and grooves the first groove and both sides of the wafer surface according to the same grooving trajectory, forming the second groove; wherein the size of the first spot is smaller than the size of the second spot, and the first groove is located in the second groove.

[0107] In one or more embodiments of the present invention, the spatial light modulator 3 shapes the laser beam in the optical path transmission system and sequentially forms a strip-shaped first light spot and a second light spot on the wafer surface, so that the first light spot and the second light spot of different sizes formed by the laser beam reaching the wafer surface sequentially groove the wafer surface according to the same set grooving trajectory, specifically including the following steps:

[0108] The spatial light modulator 3 shapes the laser beam according to the first control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped first light spot on the wafer surface, so as to groove the Low-k layer on the wafer surface according to the set grooving trajectory to form a first groove.

[0109] The spatial light modulator 3 shapes the laser beam according to the second control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped second light spot on the wafer surface. This allows for grooving of the Low-k layer on the wafer surface according to the same grooving trajectory, removing the slag on both sides of the first groove opening, and forming the second groove.

[0110] The width of the second light spot is greater than the width of the first light spot, and the first groove is located within the second groove.

[0111] A laser beam forms a strip-shaped first spot on the wafer surface, grooving the Low-k layer of the wafer surface according to a set grooving trajectory to form a first groove, thus obtaining the main structure of the groove. Then, a wider strip-shaped second spot is formed on the wafer surface using the same grooving trajectory to groove the Low-k layer of the wafer surface. This removes the slag on both sides of the first groove opening. At the same time, the energy distribution state of the second spot is controlled by the spatial light modulator 3 to precisely control the specific shape of the groove. This not only improves the grooving quality but also allows for control of the grooving precision according to different application scenarios, thus meeting the grooving processing requirements of different wafers.

[0112] Here, the spatial light modulator 3 shapes the laser beam in the optical path transmission system and sequentially forms a first and second stripe-shaped spot on the wafer surface. This allows the first and second spots of different sizes formed by the laser beam to sequentially groove the wafer surface according to the same set grooving trajectory. Grooving in two separate laser laps disperses the laser energy and avoids the water-soluble temporary protective film from reaching its irreversible modification critical temperature due to excessive laser heat during a single laser grooving. This ensures that after grooving the first and second spots, the water-soluble temporary protective film on the Low-k layer surface will not undergo irreversible modification, making it easier to clean off the water-soluble temporary protective film and slag after grooving.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wafer grooving system based on a spatial light modulator-shaped laser beam, characterized in that: Includes a laser, controller, spatial light modulator, optical transmission system, processing platform (8) and rangefinder; The laser is used to emit a laser beam; The controller is used to set the grooving trajectory, generate control commands based on the grooving trajectory and size and the slag height information fed back by the rangefinder, and send them to the spatial light modulator. The spatial light modulator (3) is disposed in the optical path transmission system and is used to shape the laser beam in the optical path transmission system according to the control command of the controller, and sequentially form a strip-shaped first light spot and a second light spot on the wafer surface, wherein the size of the first light spot is smaller than the size of the second light spot; The optical path transmission system is used to transmit the laser beam emitted and shaped by the laser to the processing platform (8). The processing platform (8) is used to clamp the wafer and adjust the position of the wafer so that the first spot and the second spot of different sizes formed by the laser beam reaching the wafer surface will be slotted twice on the wafer surface in sequence according to the same slotting trajectory. The first spot forms a first groove after slotting the wafer surface, and the second spot forms a second groove after slotting the first groove and the two sides of the wafer surface. The rangefinder is used to scan the molten slag on both sides of the first groove opening and to feed back the acquired molten slag height information to the controller.

2. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 1, characterized in that: The optical path transmission system includes a beam expander and collimator (1), a polarizer (2), a lens (4), a switching mirror (5), a focusing lens (6), a focusing objective (7), and a laser spot analyzer (9). The laser beam emitted from the laser enters the beam expander and collimator (1) and the polarizer (2) in sequence and then enters the spatial light modulator (3). After being shaped by the spatial light modulator (3), the laser beam enters the lens (4). The switching mirror (5) reflects the laser beam emitted from the lens (4) to the laser spot analyzer (9) or the focusing lens (6). The laser beam reflected to the focusing lens (6) passes through the focusing objective (7) and reaches the processing platform (8), forming a strip-shaped first spot and a second spot on the wafer surface in sequence, so as to groove the wafer surface in sequence according to the same grooving trajectory.

3. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 1, characterized in that: The controller generates control commands based on the slotting trajectory and dimensions, as well as the slag height information fed back by the rangefinder, specifically as follows: The controller determines the closed-loop energy distribution corresponding to the first light spot based on the slotting trajectory and size, generates a first control command, and sends it to the spatial light modulator (3). The controller determines the closed-loop energy distribution corresponding to the second light spot based on the slotting trajectory and size and the slag height information fed back by the rangefinder, generates a second control command, and sends it to the spatial light modulator (3).

4. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 3, characterized in that: The spatial light modulator (3) shapes the laser beam and sequentially forms a first spot and a second spot on the wafer surface, so that the first spot and the second spot formed by the laser beam on the wafer surface sequentially groove the wafer surface according to the same set grooving trajectory. The specific implementation is as follows: The spatial light modulator (3) shapes the laser beam according to the first control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped first light spot on the wafer surface, so as to groove the Low-k layer on the wafer surface according to the set grooving trajectory to form a first groove. The spatial light modulator (3) shapes the laser beam according to the second control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped second light spot on the wafer surface. It then grooves the Low-k layer on the wafer surface according to the same grooving trajectory, removes the slag on both sides of the first groove opening, and forms the second groove. The width of the second light spot is greater than the width of the first light spot, and the first groove is located within the second groove.

5. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 4, characterized in that: The width of the second light spot is at least 5 μm greater than the width of the first light spot.

6. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 4, characterized in that: The energy ratio of the second light spot to the first light spot is 0.4-0.

6.

7. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 4, characterized in that: The energy distribution of the first light spot is uniform, while the energy distribution of the second light spot is high at both ends and low in the middle.

8. The wafer grooving system based on a spatial light modulator-shaped laser beam according to claim 7, characterized in that: The energy at both ends of the second light spot accounts for 20%-50% of the total light spot energy.

9. A wafer grooving method based on a spatial light modulator-shaped laser beam, comprising the wafer grooving system based on a spatial light modulator-shaped laser beam as described in any one of claims 1-8, characterized in that, Includes the following steps: The laser emitter emits a laser beam, which is then input into the optical transmission system. The controller generates a first control command for the spatial light modulator (3) based on the set slotting trajectory and size, and sends it to the spatial light modulator; The spatial light modulator (3) installed in the optical path transmission system shapes the laser beam in the optical path transmission system according to the first control command of the controller; The optical transmission system transmits the laser beam emitted and shaped by the laser to the processing platform (8). The processing platform (8) clamps the wafer and adjusts the position of the wafer so that the first spot formed by the laser beam reaching the wafer surface can groove the wafer surface according to the set grooving trajectory to form the first groove. The rangefinder scans the molten slag on both sides of the first groove opening and feeds back the obtained molten slag height to the controller; The controller generates a second control command based on the slotting trajectory and size, as well as the slag height information fed back by the rangefinder, and sends it to the spatial light modulator. The spatial light modulator (3) installed in the optical path transmission system shapes the laser beam in the optical path transmission system according to the second control command of the controller; The optical path transmission system transmits the laser beam emitted and shaped by the laser to the processing platform (8), so that the second spot formed by the laser beam reaches the wafer surface and grooves the first groove and both sides of the wafer surface according to the same grooving trajectory, forming the second groove; wherein the size of the first spot is smaller than the size of the second spot, and the first groove is located in the second groove.

10. The wafer grooving method based on a spatial light modulator-shaped laser beam according to claim 9, characterized in that, The spatial light modulator (3) shapes the laser beam in the optical path transmission system and sequentially forms a first and a second stripe-shaped light spot on the wafer surface, so that the first and second light spots of different sizes formed by the laser beam reaching the wafer surface sequentially groove the wafer surface according to the same set grooving trajectory. The specific steps include the following: The spatial light modulator (3) shapes the laser beam according to the first control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped first light spot on the wafer surface, so as to groove the Low-k layer on the wafer surface according to the set grooving trajectory to form a first groove. The spatial light modulator (3) shapes the laser beam according to the second control command. The output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a strip-shaped second light spot on the wafer surface. It then grooves the Low-k layer on the wafer surface according to the same grooving trajectory, removes the slag on both sides of the first groove opening, and forms the second groove. The width of the second light spot is greater than the width of the first light spot, and the first groove is located within the second groove.

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