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

Abstract

The invention relates to a wafer slotting system and method based on a shaping laser beam of a spatial light modulator. The wafer slotting system comprises a laser, a controller, the spatial light modulator, a light path transmission system, a processing platform and a range finder, the laser transmitter transmits a laser beam and inputs the laser beam to the light path transmission system; the controller controls the spatial light modulator to shape laser beams in the light path transmission system, strip-shaped first light spots and strip-shaped second light spots are sequentially formed on the surface of the wafer, and the surface of the wafer is sequentially slotted according to the same set slotting track. According to the invention, the spatial light modulator is utilized to adjust the spot size, the first spot and the second spot are sequentially formed, and the surface of the wafer is sequentially slotted according to the same set slotting track, so that when the second spot is slotted, residues on the two sides of a groove when the first spot is slotted can be removed, the slotting quality is improved, and the production efficiency is improved. And meanwhile, the structure of the groove can be adjusted by adjusting the energy distribution state of the second light spot, and the advantage of accurately modulating the grooving shape is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor laser processing, and in particular to a wafer slotting system and method based on a spatial light modulator shaped laser beam. BACKGROUND

[0002] With the continuous reduction of the size of semiconductor devices and the increase of chip integration, the connection between metal interconnection layers, the parasitic capacitance between multi-layer wiring and the resistance of metal wires increase sharply, resulting in a series of problems such as RC delay and power consumption increase, which seriously affect the performance of the chip. When the device size is less than 90 nm, the wafer must use Low-K material (Low-k dielectric, low dielectric constant material) as the material for isolation and support between different layers of interconnection lines inside the integrated circuit. Since the Low-K material has a low dielectric constant, it can effectively reduce the parasitic capacitance of the metal interconnection line, thereby improving the stability and operating frequency of the chip. Therefore, the Low-K process is the focus of the development of integrated circuits at present, especially in the fields of logic operation, storage, etc.

[0003] The use of Low-K material also brings a series of problems, because the mechanical strength and adhesion performance of Low-k material are lower than those of silicon dioxide. In the chip separation process, traditional knife cutting can cause Low-K material to splash and have poor appearance, such as collapse, cracking, passivation, and metal layer lifting, which seriously affects the yield of the product.

[0004] To solve the problems caused by traditional knife cutting, the mainstream method is to use laser slotting to remove low-k and copper metal layers. Laser processing has become an effective solution for wafer processing due to its non-contact, high precision, and wide applicability.

[0005] There are two common shaping schemes: one scheme is Mask (called mask) + elliptical spot shaping system. The elliptical spot shaping system mainly shapes the original laser spot with Gaussian energy distribution into an approximate flat-top spot, and then adjusts the width of the spot through the Mask. The second scheme is to use a DOE (Diffractive Optical Element) to divide the laser into multiple beams, and through a specific point arrangement to achieve the effect of slotting with multiple Gaussian focused spots. However, both of these two ways have obvious defects:

[0006] 1. The essence of laser processing of wafer Low-k material is to use high-energy light beams to produce local high temperature in a very short time, so that the metal layer and the interlayer dielectric are rapidly melted, vaporized and ejected, thereby completing the precise removal of the material. Therefore, the evaporation and ejection of the Low-k interlayer dielectric and metal material on the wafer surface during the laser processing process will produce residues that will adhere to the wafer surface, thereby affecting the material's yield and processing quality;

[0007] 2. The conventional shaping method cannot adjust the energy distribution of the shaped spot, so it cannot adjust the groove structure in real time after grooving. Different wafer samples require different grooving processes, such as some wafer samples require a "N" type groove with a large bottom groove width for subsequent diamond wheel cutting, and some wafer samples require a "U" type groove with high strength. The conventional shaping method cannot meet such different needs.

[0008] In addition, in the laser grooving process, in order to protect the Low-k dielectric layer from contaminant penetration, a water-soluble temporary protective film is usually pre-coated. Such film will irreversibly modify due to high heat load during laser processing. Due to the thermal chemical deformation of the water-soluble temporary film, the cleaning liquid cannot penetrate, resulting in the inability to clean the film and slag in the subsequent cleaning process. SUMMARY

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

[0010] The technical solution of the present application to solve the above technical problems is as follows: a wafer grooving system 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 range finder;

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

[0012] The controller is used to set a grooving track, generate a control instruction according to the grooving track and size and the slag height information fed back by the range finder, and send it to the spatial light modulator;

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

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

[0015] The processing platform is used to clamp the wafer and adjust the position of the wafer, so that the laser beam reaches the wafer surface to form different sizes of the first spot and the second spot in turn according to the same grooving track set by the controller, and then grooves the wafer surface twice, wherein the first spot forms a first groove after grooving on the wafer surface, and the second spot forms a second groove after grooving on the first groove and both sides of the wafer surface;

[0016] The range finder is used for scanning the molten slag on both sides of the first groove notch, and feeding the obtained molten slag height information to the controller.

[0017] The wafer grooving system based on the spatial light modulator shaping laser beam has the advantages that: the spatial light modulator is used for adjusting the shaping spot size, the first spot and the second spot are sequentially formed, and the fast switching of different shaping spot sizes in the cutting groove in the Low-k layer of the wafer surface is realized, so that the wafer surface is sequentially grooved according to the same grooving track set by the first spot and the second spot. The second spot can accurately remove the molten slag on both sides of the first groove when the first groove is grooved, the problem of molten slag generated in the processing of the Low-k layer on the wafer surface is solved, the effect of high-quality grooving is realized, and the energy distribution state of the second spot can be adjusted to adjust the structure of the groove. The groove type is accurately modulated, and the laser grooving is performed twice, so that the laser energy can be dispersed, the high-heat critical point of irreversible modification of the water-soluble temporary protective film caused by high heat when the laser grooving is performed once is avoided, and the water-soluble temporary protective film and the molten slag can be cleaned after the grooving is completed.

[0018] Based on the above technical solutions, the application can be further improved as follows:

[0019] Further, the optical transmission system comprises a beam expanding and collimating element, a polarizer, a lens, a switching mirror, a focusing lens, a focusing objective lens and a laser spot analyzer, the laser beam emitted by the laser enters the beam expanding and collimating element and the polarizer in sequence and then is incident on the spatial light modulator, the laser beam shaped by the spatial light modulator is incident on the lens, the switching mirror reflects the laser beam emitted by the lens to the laser spot analyzer or the focusing lens, and the laser beam reflected to the focusing lens passes through the focusing objective lens and reaches the workbench, and the first spot and the second spot in the form of a strip are formed on the wafer surface in sequence to groove the wafer surface according to the same grooving track set.

[0020] The above-mentioned further scheme has the advantages that: the beam expanding and collimating element can perform beam expanding and collimating processing on the laser beam emitted by the laser, then the polarizer is used for polarization control, and the laser beam is incident on the spatial light modulator, the laser beam shaped by the spatial light modulator is incident on the lens for focusing, then the laser beam is reflected to the laser spot analyzer or the focusing lens by the reflecting mirror, the laser spot analyzer can analyze the spot parameters, the laser beam incident on the focusing lens is emitted after focusing and reaches the workbench, and the first spot and the second spot in the form of a strip are formed on the wafer surface in sequence, so that the wafer surface Low-k layer is grooved.

[0021] Further, the controller generates the control instructions according to the slotting trajectory and size and the molten slag height information fed back by the distance meter, and the specific implementation is as follows:

[0022] The controller determines the closed-loop energy distribution corresponding to the first light spot according to the slotting trajectory and size, generates the first control instructions, and sends them to the spatial light modulator.

[0023] The controller determines the closed-loop energy distribution corresponding to the second light spot according to the slotting trajectory and size and the molten slag height information fed back by the distance meter, generates the second control instructions, and sends them to the spatial light modulator.

[0024] The beneficial effect of the above further scheme is that the control commands for the first slotting can be accurately generated according to the slotting trajectory and size, and the closed-loop energy distribution corresponding to the second light spot can be accurately determined according to the molten slag height fed back by the distance meter during the second slotting, so that the corresponding second light spot can be accurately obtained.

[0025] Further, the spatial light modulator shapes the laser beam and sequentially forms the first light spot and the 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 follow the same slotting trajectory set to slot the wafer surface, and the specific implementation includes the following steps:

[0026] The spatial light modulator shapes the laser beam according to the first control instructions, 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 to slot the Low-k layer of the wafer surface according to the set slotting trajectory and form a first groove.

[0027] The spatial light modulator shapes the laser beam according to the second control instructions, 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 to slot the Low-k layer of the wafer surface according to the same set slotting trajectory, remove the molten slag on both sides of the first groove, and form a second groove.

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

[0029] The beneficial effect of the above further scheme is that: by forming a strip-shaped first light spot on the wafer surface through the laser beam to groove the Low-k layer on the wafer surface according to the set groove track to form a first groove, and then forming a wider strip-shaped second light spot on the wafer surface through the laser beam to groove the Low-k layer on the wafer surface along the same groove track, the slag on both sides of the first groove can be removed, and the specific shape of the groove can be accurately controlled by controlling the energy distribution state of the second light spot through the spatial light modulator, which not only improves the quality of grooving, but also controls the precision of grooving according to different application scenarios to meet the grooving processing requirements of different wafers.

[0030] Further: the width of the second light spot is at least 5 μm larger than the width of the first light spot.

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

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

[0033] The beneficial effect of the above further scheme is that: by adjusting the energy of the second light spot and the first light spot, on the one hand, the efficiency of grooving can be improved, and on the other hand, the slag on both sides of the first groove can be removed by the second light spot during grooving, without generating much new slag, greatly improving the quality of grooving.

[0034] Further: the energy distribution of the first light spot is in a uniform distribution state, and the energy distribution of the second light spot is in a distribution state of high energy at both ends and low energy in the middle.

[0035] The beneficial effect of the above further scheme is that: by setting the energy distribution of the first light spot to be in a uniform distribution state, the required groove structure can be machined on the predetermined grooving track of the wafer, so that the first light spot forms the main structure of the required groove on the wafer pre-cutting path, and by setting the energy distribution of the second light spot to be in a distribution state of high energy at both ends and low energy in the middle, the slag on both sides of the groove can be effectively removed by the second light spot with high energy at both ends when machining the first groove structure formed by the first light spot, which can increase the width of the groove while accurately controlling the shape of the groove by controlling the proportion of the energy of the second beam at both ends to the overall energy.

[0036] Further: the proportion of the energy of the second light spot at both ends to the overall light spot energy is in the range of 20%-50%.

[0037] The application also provides a wafer slotting method based on a spatial light modulator shaped laser beam, which adopts the wafer slotting system based on the spatial light modulator shaped laser beam and comprises the following steps.

[0038] The laser transmitter transmits a laser beam and inputs the laser beam into the optical path transmission system;

[0039] The controller generates a first control instruction according to the set slotting track and size and sends the first control instruction to the spatial light modulator;

[0040] The spatial light modulator arranged in the optical path transmission system shapes the laser beam in the optical path transmission system according to the first control instruction of the controller;

[0041] The optical path transmission system transmits the laser beam emitted and shaped by the laser to the machining platform;

[0042] The machining platform clamps the wafer and adjusts the position of the wafer, so that the first spot formed by the laser beam reaching the wafer surface slots the wafer surface according to the set slotting track and forms a first groove;

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

[0044] The controller generates a second control instruction according to the slotting track and size and the slag height information fed back by the range finder and sends the second control instruction to the spatial light modulator;

[0045] The spatial light modulator arranged in the optical path transmission system shapes the laser beam in the optical path transmission system according to the second control instruction of the controller;

[0046] The optical path transmission system transmits the laser beam emitted and shaped by the laser to the machining platform, so that the second spot formed by the laser beam reaching the wafer surface slots the first groove and both sides of the wafer surface according to the set same slotting track and forms a 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] On the basis of the above technical solution, the application can also be improved as follows:

[0048] Further, the spatial light modulator shapes the laser beam in the optical path transmission system and sequentially forms the first spot and the second spot in the form of a strip on the wafer surface, so that the laser beam reaches the wafer surface to form the first spot and the second spot with different sizes and sequentially slots the wafer surface according to the set same slotting track, and specifically comprises 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 groove track and form 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 light spot on the wafer surface, so as to groove the Low-k layer on the wafer surface according to the same set groove track, remove the slag on both sides of the first groove, and form a 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 in the second groove.

[0052] After the first groove is processed, the height data of the slag on both sides of the first groove is tested by the laser range finder on the equipment, and the height data of the slag is fed back to the computer to control the energy distribution of the second light spot through a specific software algorithm to accurately control the slag generated by the first light spot. The specific method is that when the laser range finder reads the height of the slag on both sides of the first groove is higher, the energy on both sides of the second light spot is increased to increase the processing amount of the material on both sides of the second groove to remove the slag with higher height, and when the height on both sides of the first groove is lower, the energy on both sides of the second light spot is reduced to reduce the processing amount of the material on both sides of the second groove. The closed-loop slag removal method realizes the function of dynamic and accurate control of the groove slag.

[0053] The beneficial effects of the above further scheme are: the laser beam forms a strip-shaped first light spot on the wafer surface to groove the Low-k layer on the wafer surface according to the set groove track and form a first groove, and then the laser beam forms a wider strip-shaped second light spot on the wafer surface to groove the Low-k layer on the wafer surface according to the same groove track, so that the slag on both sides of the first groove can be removed, and the energy distribution state of the second light spot is controlled by the spatial light modulator to accurately control the specific shape of the groove. Not only improves the quality of grooving, but also can control the accuracy of grooving according to different application scenarios to meet the grooving processing requirements of different wafers. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 It is a structure schematic view of a wafer grooving system based on a spatial light modulator shaping laser beam according to an embodiment of the present application;

[0055] Figure 2 It is a structure of a first light spot and a second light spot and corresponding first grooves and second grooves according to an embodiment of the present application;

[0056] Figure 3 An energy distribution diagram of a first light spot of an embodiment of the present application;

[0057] Figure 4 An energy distribution diagram of a second light spot of an embodiment of the present application;

[0058] Figure 5 A structure of a first light spot and a second light spot and corresponding first grooves and second grooves of another embodiment of the present application;

[0059] Figure 6 A flowchart of a wafer grooving method based on a spatial light modulator shaping laser beam of an embodiment of the present application.

[0060] In the drawings, the components represented by each reference numeral are listed as follows:

[0061] 1, beam expansion collimation element, 2, polarizer, 3, spatial light modulator, 4, lens, 5, switching mirror, 6, focusing lens, 7, focusing objective lens, 8, machining platform. DETAILED DESCRIPTION

[0062] The principles and features of the present application are described below in conjunction with the accompanying drawings, and the examples are only used to explain the present application and are not intended to limit the scope of the present application.

[0063] The present application is directed to the problem of slag attachment on both sides of the groove after processing the specific cutting path on the wafer surface in the laser grooving process, and the accumulation of slag is reduced by changing the width of the shaped light spot during grooving. Specifically as follows:

[0064] As shown in Figure 1 A wafer grooving system based on a spatial light modulator shaping laser beam, comprising a laser, a controller, a spatial light modulator, an optical transmission system, a machining platform 8 and a range finder;

[0065] The laser is configured to emit a laser beam.

[0066] The controller is configured to set a grooving track, generate a control instruction according to the grooving track and size and slag height information fed back by the range finder, and send the control instruction to the spatial light modulator.

[0067] The spatial light modulator 3 is disposed in the optical transmission system and is configured to shape the laser beam in the optical transmission system according to the control instruction of the controller, and sequentially form a first light spot and a second light spot in the form of a strip 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 transmission system is configured to transmit the shaped laser beam emitted by the laser to the machining platform 8.

[0069] The processing platform 8 is used for clamping the wafer and adjusting the position of the wafer, so that the laser beam reaches the wafer surface to form different sizes of first and second light spots in turn according to the same slotting track set to perform twice slotting on the wafer surface, wherein the first light spot forms a first groove after slotting on the wafer surface, and the second light spot forms a second groove after slotting on the wafer surface and both sides of the first groove.

[0070] The range finder is used for scanning the slag on both sides of the first groove opening and feeding the obtained slag height information to the controller.

[0071] The wafer slotting system based on the spatial light modulator shaping laser beam of the application adjusts the size of the shaped light spot by using the spatial light modulator, sequentially forms first and second light spots, and realizes the rapid switching of different shaped light spot sizes in the same cutting path on the wafer surface Low-k layer, so that the first and second light spots are sequentially slotting on the wafer surface according to the same slotting track set, so that the second light spot can accurately remove the slag on both sides of the first groove when the first light spot is slotting, solve the problem of slag generated by processing the Low-k layer on the wafer surface, realize the effect of high-quality slotting, and also adjust the structure of the groove by adjusting the energy distribution state of the second light spot, has the advantages of accurate modulation of the slot type, and can disperse the laser energy by twice laser slotting, avoid the high heat critical point of irreversible modification of the water-soluble temporary protective film due to high heat when single laser slotting is used, so that the cleaning liquid can be easily infiltrated, so that the water-soluble temporary protective film and slag can be easily cleaned after slotting.

[0072] In one or more embodiments of the application, the optical transmission system includes a beam expander collimating element 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 by the laser enters the beam expander collimating element 1 and the polarizer 2 in turn and then is incident on the spatial light modulator 3, the laser beam shaped by the spatial light modulator 3 is incident on the lens 4, the switching mirror 5 reflects the laser beam emitted by 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 workbench 8, and first and second light spots in the form of strips are formed on the wafer surface in turn to perform slotting on the wafer surface according to the same slotting track set.

[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 size, 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 of the middle, the blue long bar is the first light spot, and the white long bar is the first groove formed by slotting.

[0081] In practice, a small size first light spot with relatively uniform energy is used to pre-process the preset cutting path on the wafer surface to form a first groove on the preset cutting path. At this time, there is a residue with a width of 2-3 μm and a height of about 3 μm on both sides of the first groove on the preset cutting path, as shown in the lower left of the middle. Figure 2

[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 to groove the Low-k layer of the wafer surface according to the set same slotting track, remove the slag on both sides of the first groove, and form a second groove at the same time, as shown in the upper right of the middle. Figure 2

[0083] Here, the second light spot (the width of the second light spot is more than 5 μm larger than the width of the first light spot) is used to perform the slotting process on the predetermined cutting of the wafer surface. Since the slag on both sides of the slot of the first groove will be removed, and the inside of the slot will be hollowed out when the second groove is formed, there will be only a small amount of slag on the outside of the slot, thereby achieving the effect of slotting while reducing the slag in the slot and improving the slotting quality, as shown in the lower right of the middle. Figure 2

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

[0085] After the first groove is processed, the height data of the slag on both sides of the first groove is detected by the distance meter on the equipment, and the height data of the slag is fed back to the controller. The controller controls the energy distribution of the second light spot through a software algorithm, and then accurately removes the slag generated by the first light spot. The specific method is that when the distance meter reads that the height of the slag on both sides of the first groove is high, the height of the slag is removed by increasing the energy on both sides of the second light spot to increase the material processing amount on both sides of the second groove. When the energy on both sides of the first groove is low, the energy on both sides of the second light spot is reduced to reduce the material processing amount on both sides of the second groove. This closed-loop slag removal method realizes the function of dynamic and accurate control of the slag in the slot of the first groove. Here, the distance meter can use the existing distance meter of Keyence.

[0086] ​​​The first light spot in the shape of a strip is formed on the wafer surface by a laser beam to groove the Low-k layer on the wafer surface according to a set groove track, and a first groove is formed, thereby obtaining a main structure of the groove; then, the second light spot in the shape of a wider strip is formed on the wafer surface by a laser beam to groove the Low-k layer on the same groove track, so that the slag on both sides of the first groove can be removed, and the specific shape of the groove can be accurately controlled by controlling the energy distribution state of the second light spot through the spatial light modulator 3, thereby improving the quality of the groove and controlling the precision of the groove according to different application scenarios to meet the groove processing requirements of different wafers.

[0087] Optionally, in one or more embodiments of the present application, the width of the second light spot is at least 5 μm larger than the width of the first light spot. By controlling the width of the second light spot and the first light spot, the slag generated during the grooving process can be reduced as much as possible, and the efficiency of the grooving can be improved as much as possible.

[0088] Optionally, in one or more embodiments of the present application, 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, on the one hand, the efficiency of the grooving can be improved, and on the other hand, the slag on both sides of the first groove can be removed by the second light spot during the grooving, and more new slag will not be generated, thereby greatly improving the quality of the grooving.

[0089] As shown in Figure 3 and Figure 4 , in one or more embodiments of the present application, Figure 3 , the energy distribution of the first light spot is in a uniform distribution state, Figure 4 , the energy distribution of the second light spot is in a distribution state of high energy at both ends and low energy in the middle. By setting the energy distribution of the first light spot to be in a uniform distribution state, the required groove structure on the predetermined groove track of the wafer can be processed, and the first light spot can form the main structure of the required groove on the wafer pre-cutting path. By setting the energy distribution of the second light spot to be in a distribution state of high energy at both ends and low energy in the middle, the slag on both sides of the groove can be effectively removed by the second light spot with high energy at both ends, and the width of the groove can be increased, and the shape of the groove can be accurately controlled by controlling the proportion of the energy at both ends of the second beam shaping light spot to the overall energy.

[0090] Optionally, in one or more embodiments of the present application, the proportion of the energy at both ends of the second light spot to the overall light spot energy is in the range of 20%-50%.

[0091] Since the first light spot needs to process the required groove structure on the wafer pre-cutting path, the energy distribution of the first light spot is shaped as a nearly uniform distribution, so that the first light spot can form the main body structure of the required groove on the wafer pre-cutting path, and then the first groove structure of the first step is processed by using the second light spot. Specifically, the energy distribution of the second light spot is high at both ends and low in the middle, and the high-energy shaped light spot at both ends can effectively remove the residues on both sides of the groove during processing, thereby increasing the width of the groove and accurately controlling the shape of the second groove by controlling the proportion of the energy at both ends of the second light spot.

[0092] Specifically, as shown in Figure 3 and Figure 4 the light spot of the laser beam can be viewed in the light spot analyzer, and the proportion of the energy at both ends of the second light spot to the total light spot energy is 20%-50%, which can accurately control the groove type of the processed groove. When the proportion of the energy at both ends to the total energy is 50%, the required “N” type groove can be processed, as shown in Figure 5 the left side, which is beneficial to improve the groove width ratio (the ratio of the lower groove width to the upper groove width of the groove type), and facilitates the cutting processing of the cutter wheel in the subsequent cutter wheel processing. When the proportion of the energy at both ends to the total energy is 20%, the required “∪” type groove can be processed, as shown in Figure 5 the right side, at which time the junction of the groove bottom to the groove wall is relatively smooth with a circular arc transition, which avoids stress concentration and is beneficial to improve the strength of the chip.

[0093] The present application first uses a small-sized first light spot to pre-process the predetermined cutting path on the wafer surface, and in the processing process, the molten slag is accumulated on both sides of the first groove. In the next step, a large-sized second light spot is used to groove processing at the position of the previous step, and the large-sized second light spot will cover the groove processed by the small-sized shaped light spot and the molten slag on both sides during the grooving. At this time, the large-sized second light spot will melt and remove the pre-processed second groove and the molten slag of the groove opening at the same time, thereby achieving the effect of less molten slag of the groove opening and improving the quality of the grooving.

[0094] Meanwhile, according to the process requirements of different wafer samples of customers, if there are specific requirements for the groove shape after grooving processing, such as the “N” type or “∪” type groove. The proportion of the energy at both ends of the shaped second light spot to the total energy is controlled by using the spatial light modulator 3, so as to control the shape of the second groove after grooving on the specific cutting path of the wafer. When the proportion of the energy at both ends of the second light spot is high, the “N” type groove can be obtained, and when the proportion of the energy at both ends of the shaped light spot is low, the “∪” type groove can be obtained.

[0095] The application realizes the rapid switching of different shaped light spot sizes in the cutting channel of the wafer surface Low-k layer by utilizing the characteristics of the spatial light modulator, solves the problem of slag generated by the wafer surface Low-k layer processing, controls the groove structure according to the characteristics of the spatial light modulator to meet the slotting processing requirements of different wafers, so as to realize the high-quality slotting effect, and controls the shape of the second groove after slotting by controlling the energy size of the two ends of the second light spot, so as to realize the precise modulation of the slotting groove.

[0096] It should be particularly pointed out that in the embodiments of the application, more laser beams can also be arranged, and different width strip-shaped light spots can be sequentially formed on the wafer surface, and slotting processing can be sequentially performed on the predetermined cutting channel of the wafer surface, so as to form a groove with a specific shape on the predetermined cutting channel of the wafer surface.

[0097] As shown in Figure 6 The application also provides a wafer slotting method based on a spatial light modulator shaped laser beam, which adopts the wafer slotting system based on the spatial light modulator shaped laser beam, and includes the following steps:

[0098] The laser emitter emits a laser beam and inputs it into the optical path transmission system;

[0099] The controller generates a first control instruction according to the set slotting track and size to the spatial light modulator 3 and sends it to the spatial light modulator;

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

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

[0102] The processing platform 8 clamps the wafer and adjusts the position of the wafer, so that the first light spot formed on the wafer surface by the laser beam performs slotting on the wafer surface according to the set slotting track, and forms a first groove;

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

[0104] The controller generates a second control instruction according to the slotting track and size and the slag height information fed back by the range finder and sends it to the spatial light modulator;

[0105] The spatial light modulator 3 arranged in the optical path transmission system shapes the laser beam in the optical path transmission system according to the second control instruction 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 reaching the wafer surface is slotted according to the same slotted track set on the first groove and both sides of the wafer surface, forming a 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 application, the spatial light modulator 3 shapes the laser beam in the optical path transmission system, and sequentially forms a first spot and a second spot on the wafer surface in the form of a strip, so that the first spot and the second spot of different sizes formed by the laser beam reaching the wafer surface are sequentially slotted according to the same slotted track set, specifically including the following steps:

[0108] The spatial light modulator 3 shapes the laser beam according to the first control instruction, and the output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a first spot in the form of a strip on the wafer surface, so as to slot the Low-k layer of the wafer surface according to the set slotted track, forming a first groove;

[0109] The spatial light modulator 3 shapes the laser beam according to the second control instruction, and the output laser beam reaches the wafer surface after passing through the optical path transmission system, forming a second spot in the form of a strip on the wafer surface, so as to slot the Low-k layer of the wafer surface according to the same slotted track set, and remove the slag on both sides of the first groove, and form a second groove;

[0110] Wherein, the width of the second spot is greater than the width of the first spot, and the first groove is located in the second groove.

[0111] By forming a first spot in the form of a strip on the wafer surface by the laser beam, the Low-k layer of the wafer surface is slotted according to the set slotted track, forming a first groove to obtain the main structure of the groove, and then forming a second spot in the form of a strip on the wafer surface by the laser beam, the Low-k layer of the wafer surface is slotted according to the same slotted track, so that the slag on both sides of the first groove can be removed, and the energy distribution state of the second spot is controlled by the spatial light modulator 3 to accurately control the specific shape of the groove, not only improving the quality of the slotting, but also controlling the precision of the slotting according to the requirements of different application scenarios, to meet the slotting 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 the first light spot and the second light spot in the strip shape on the wafer surface, so that the laser beam reaches the first light spot and the second light spot of different sizes formed on the wafer surface in turn according to the same slotting track set, and the wafer surface is slotting in two times of laser in turn. The laser energy can be dispersed, the irreversible modification critical temperature of the water-soluble temporary protective film is avoided when the laser heat is too high in single laser slotting, the irreversible modification of the water-soluble temporary protective film on the surface of the Low-k layer is avoided after the first light spot and the second light spot are slotting processed, so that the water-soluble temporary protective film and the slag can be cleaned after the slotting is completed.

[0113] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

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 stage (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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