Method for dividing processing object including substrate layer and at least one material layer

Abstract

The disclosed method for dividing a processing object comprises the steps of: preparing a processing object including a substrate layer and at least one material layer formed on the upper surface of the substrate layer; shaping laser light into a processing beam; forming a recess to be cut that partially extends from the material layer to the inside of the substrate layer, while relatively moving the processing beam one or more times in the processing direction with respect to the processing object; and dividing the processing object along the recess to be cut. In at least one relative movement from among the one or more relative movements in the step of forming the recess to be cut, the processing beam has a Gaussian intensity profile, and the recess to be cut having a shape of which the width becomes narrower as the depth increases in a cross section orthogonal to the processing direction is formed in the processing object by the processing beam having the Gaussian intensity profile.

Description

Method for dividing a workpiece comprising a substrate layer and at least one material layer

[0001] The present disclosure relates to a method for dividing a processing object, and more particularly, to a method for forming a cutting groove in a processing object and dividing the processing object along the cutting groove.

[0002] In semiconductor manufacturing, glass substrates, silicon substrates, sapphire substrates, and other substrates are used as wafers. To separate the multiple circuit elements formed on the wafer during the semiconductor manufacturing process or after the semiconductor manufacturing process is complete, the wafer must be cut.

[0003] Among cutting methods, there is the mechanical cutting method, which uses a rotating saw blade to cut the wafer. Mechanical cutting methods pose a risk of damage to circuit elements on the wafer due to debris generated during the cutting process. Furthermore, mechanical cutting methods have the disadvantage of being very slow, requiring blade replacement costs and time due to blade wear. Furthermore, microcracks may form near the cut line.

[0004] Among laser cutting methods, there is laser full cutting, which completely cuts the wafer. Laser full cutting is difficult to apply to thick wafers.

[0005] A hybrid cutting method involves removing semiconductor patterns on a wafer using a laser, followed by mechanical cutting. However, this method requires two separate cutting processes, which can be time-consuming and reduce productivity. Furthermore, the need for both laser and mechanical cutting equipment increases equipment costs and requires a significant amount of space on the production line.

[0006] The present disclosure provides a method for dividing a processing object capable of dividing the processing object through laser processing.

[0007] The present disclosure provides a method for dividing a workpiece with improved productivity.

[0008] A method for dividing a processing object according to one aspect of the present disclosure comprises the steps of: preparing a processing object including a substrate layer and at least one material layer formed on an upper surface of the substrate layer; shaping laser light into a processing beam; forming a cutting groove that partially extends from the material layer to the inside of the substrate layer while relatively moving the processing beam relative to the processing object one or more times in a processing direction; and dividing the processing object along the cutting groove, wherein in at least one of the one or more relative movements in the step of forming the cutting groove, the processing beam has a Gaussian intensity profile, and the cutting groove is formed in the processing object by the processing beam having the Gaussian intensity profile in a cross-section perpendicular to the processing direction, the width of which becomes narrower as the depth increases and having a sharp end.

[0009] As an example, the laser light may be pulsed laser light having a pulse width of 1 μs or less.

[0010] In one embodiment, the processing beam may include a first processing beam having a flat-top strength profile and a second processing beam having a Gaussian strength profile. The step of forming the cutting groove may include a first processing step of forming a first cutting groove having a shape having a flat lower surface in a cross-section perpendicular to the processing direction in the processing object while relatively moving the first processing beam at least once along the cutting line; and a second processing step of forming a second cutting groove having a shape having a width that becomes narrower as the depth increases and a sharp end in a cross-section perpendicular to the processing direction extending from the lower surface of the first cutting groove into the interior of the substrate layer while relatively moving the second processing beam at least once along the cutting line.

[0011] As an example, the formation range of the first cutting groove in the thickness direction of the processing object may be formed in one range among a part of the material layer, the entire material layer, and the entire material layer and a part of the substrate layer.

[0012] As an example, the width of the second cutting groove may be smaller than the width of the first cutting groove.

[0013] As an example, the width of the first cutting groove may be at least three times the width of the second cutting groove.

[0014] As an example, the depth of the second cutting groove may be at least 2.5 times the width of the upper edge of the second cutting groove.

[0015] As an example, the distance from a reference line extending in the thickness direction of the processing object from the pointed end of the second cutting groove to the upper edge of the second cutting groove may be 5 μm or less.

[0016] As one embodiment, the first processing beam includes a plurality of first processing beams spaced apart from each other in the processing direction, the second processing beam includes a plurality of second processing beams spaced apart from each other in the processing direction, and the number of the plurality of first processing beams may be less than the number of the plurality of second processing beams.

[0017] As an example, the second processing beam includes a plurality of second processing beams spaced apart from each other in the processing direction, and a spot size of the plurality of second processing beams may be 20 μm or less.

[0018] As an example, the spacing between the plurality of second processing beams may be 1 to 5 mm.

[0019] In one embodiment, the step of preparing the object to be processed may include a step of reducing the thickness of the object to be processed by polishing the lower surface of the substrate layer; and a step of adhering the object to be processed onto a stretched film. The step of dividing the object to be processed may include a step of stretching the stretched film to form a crack from the sharp end of the groove to be cut to the lower surface of the substrate layer.

[0020] As an example, with respect to the object to be processed after polishing, the sharp end of the groove to be cut may be positioned within a range of 5 to 10 μm from the lower surface of the substrate layer.

[0021] As an example, after polishing, the pointed end of the groove to be cut may be positioned in a range of 30% to 80% of the thickness of the substrate layer from the upper surface of the substrate layer.

[0022] As one embodiment, the step of dividing the object to be processed may include a step of polishing the lower surface of the substrate layer at least to a position adjacent to a pointed end of the groove to be cut.

[0023] In one embodiment, the machining beam has a Gaussian intensity profile in all of the one or more relative movements, and the machining beam having a Gaussian intensity profile may include a plurality of machining beams arranged in the machining direction.

[0024] As an example, the spot size of the plurality of processing beams may be 20 μm or less.

[0025] As an example, the spacing between the plurality of processing beams may be 1 to 5 mm.

[0026] In one embodiment, the groove to be cut includes a first portion extending downward from the material layer, and a second portion having a shape that becomes narrower as the depth increases in a cross-section perpendicular to the processing direction and has a pointed end, which partially extends from the first portion into the interior of the substrate layer, and the width of the first portion may be greater than the width of the second portion.

[0027] As an example, the depth of the groove to be cut may be at least 2.5 times the width of the upper edge of the first portion.

[0028] According to embodiments of the method for dividing a processing object of the present disclosure, a V-shaped cutting groove is formed in the processing object using a processing beam having a Gaussian intensity profile, and the processing object is divided using this cutting groove as a starting point. Therefore, efficient division processing is possible compared to conventional methods that combine laser processing and mechanical processing.

[0029] By dividing the processing beam into multiple processing beams spaced apart in the processing direction and processing them, the occurrence of debris, burrs, etc. can be reduced, and since molten by-products can be removed by the subsequent processing beam, it is possible to form a high-quality cutting groove.

[0030] By forming a first cutting groove in a material layer using a first machining beam having a flat-top strength profile and then forming a second cutting groove in a substrate layer using a second machining beam having a Gaussian strength profile, formation of a high-quality cutting groove is possible.

[0031] FIG. 1 is a schematic diagram of a laser processing device according to one embodiment of the present disclosure.

[0032] Figure 2 is a schematic plan view of one embodiment of a processing target.

[0033] Figure 3 is a schematic cross-sectional view of one embodiment of a processing target.

[0034] Figure 4 is a schematic cross-sectional view of one embodiment of a processing target.

[0035] FIG. 5 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure.

[0036] FIG. 6 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure.

[0037] Figure 7 is a drawing showing an example of a step of preparing a workpiece including a polishing process.

[0038] Figure 8 is a drawing showing an example of the first processing step.

[0039] Figure 9 shows an example of a process for forming a first cutting groove.

[0040] Figure 10 shows examples of the first cut-off grooves.

[0041] Figure 11 is a drawing showing an example of a secondary processing step.

[0042] Figure 12 shows an example of a process for forming a second cutting groove.

[0043] Figure 13 is a detailed drawing of an example of a first cutting plan home and a second cutting plan home.

[0044] Figure 14 is a drawing showing an example of a step of dividing a processing target.

[0045] FIG. 15 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure.

[0046] Figure 16 is a detailed drawing of an example of a first cutting plan home and a second cutting plan home.

[0047] Figure 17 is a drawing showing an example of a step of dividing a processing target.

[0048] FIG. 18 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure.

[0049] Figure 19 shows an example of a groove to be cut.

[0050] FIG. 20 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure.

[0051] Figure 21 is a detailed drawing of an example of a groove to be cut.

[0052] Figure 22 is a drawing showing an example of a step of dividing a processing target.

[0053] Hereinafter, embodiments of a method for dividing a processing object according to the present disclosure will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals designate the same components, and the size or thickness of each component may be exaggerated for clarity of explanation.

[0054] FIG. 1 is a schematic diagram of a laser processing device according to one embodiment of the present disclosure. Referring to FIG. 1, the laser processing device may include a stage (100) on which a processing target (1) is mounted, a laser generator (200) that generates laser light (L), an optical system (300) that shapes the laser light (L) and focuses it on the processing target (1), and a control unit (400) that controls the laser processing device.

[0055] FIG. 2 is a schematic plan view of one embodiment of a processing object (1). FIG. 3 is a schematic cross-sectional view of one embodiment of a processing object (1). FIG. 4 is a schematic cross-sectional view of one embodiment of a processing object (1). Referring to FIGS. 2 to 4, the processing object (1) may include a substrate layer (11) having at least one material layer formed on an upper surface thereof. The substrate layer (11) may be, for example, a wafer used in a semiconductor process, such as a glass substrate, a silicon substrate, or a sapphire substrate. The substrate layer (11) may also be referred to as a wafer or a substrate. The at least one material layer may include a pattern layer (13) formed on the substrate layer (11) through a series of semiconductor processes to form a semiconductor element (12). Although not depicted in detail in the drawings, the pattern layer (13) may include a semiconductor element pattern and a metal pattern. The at least one material layer may further include a covering layer (14) covering the pattern layer (13). The covering layer (14) may be, for example, a protective layer for protecting the pattern layer (13), but is not limited thereto, and may be a functional layer required for the semiconductor element (12) to be applied to a subsequent process. The thickness of the material layer is not particularly limited. As a non-limiting example, the thickness of the pattern layer (13) may be approximately 10 to 20 μm. As a non-limiting example, the thickness of the pattern layer (13) may be approximately 10 to 30 μm. As a non-limiting example, the thickness of the covering layer (14) may be approximately 5 to 10 μm.

[0056] By dividing the workpiece (1) along the cutting line (15), a plurality of semiconductor elements (12) can be individually separated. The cutting line (15) illustrated in Fig. 2 is not a line formed on the surface of the actual workpiece (1), but is a virtual line indicating the position where the cutting groove described later is to be formed.

[0057] A workpiece (1) is mounted on a stage (100). Although not shown in the drawing, a fixing means for fixing the workpiece (1) to the stage (100) may be provided. For example, the fixing means may be a vacuum chuck. The stage (100) may be moved laterally, for example, in the X direction, or in the X direction and the Y direction, by a moving means not shown. The stage (100) may also be moved in the Z direction perpendicular to the X direction and the Y direction. The stage (100) may also be rotated about the Z direction as an axis. For example, the stage (100) may be moved in the X direction to form a cutting groove extending in the X direction. Then, the stage (100) may be rotated 90 degrees with respect to the Z direction and moved in the X direction to form a cutting groove extending in the Y direction.

[0058] A laser generator (200) generates laser light (L). The laser light (L) may be, for example, collimated parallel light. The laser light (L) may be pulsed laser light having a pulse width of 1 μs or less. The laser light (L) may be, for example, ultrashort pulsed laser light having a pulse width of the nanosecond order, picosecond order, or femtosecond order. For example, the laser light (L) may have a pulse width of the femtosecond order. This can reduce the occurrence of a heat affected zone (HAZ) during the processing. The laser light (L) has very high focusing properties and can focus up to the diffraction limit. For example, the power of the laser light (L) may be 1 to 100 W. For example, the frequency of the laser light (L) may be, for example, 2 MHz.

[0059] The optical system (300) shapes the laser light (L) to have a power profile suitable for processing and focuses it on the processing target (1). For example, the optical system (300) can split the laser light (L) into two processing beams having different intensity profiles and focus them on the processing target (1), respectively. For example, the optical system (300) can split each of the two processing beams having different intensity profiles into a plurality of processing beams and focus them on the processing target (1).

[0060] For example, the beam splitter (310) splits the laser light (L) into first and second laser lights (L1) (L2). The optical configuration of the beam splitter (310) is not particularly limited. The beam shaper (320) shapes the first laser light (L1) into a first processing beam (L11) having a flat-top intensity profile. In addition, the beam shaper (320) shapes the second laser light (L2) into a second processing beam (L21) having a Gaussian intensity profile. The attenuator (330) adjusts the power of the first and second processing beams (L11) (L21). For example, the attenuator (330) can provide the second processing beam (L21) to the processing object (1) by setting the power of the first processing beam (L11) to "0", and can provide the first processing beam (L11) to the processing object (1) by setting the power of the second processing beam (L21) to "0". The attenuator (300) can be arranged in front of the beam shaper (320) to selectively adjust the power of the first and second laser lights (L1) (L2) to "0".

[0061] As an example, the optical system (300) can split each of the first and second processing beams (L11) (L21) into a plurality of processing beams and provide them to the processing object (1). For example, the first beam splitter (341) can split the first processing beam (L11) into a plurality of first processing beams (L12) spaced apart in the processing direction (e.g., X direction). The plurality of first processing beams (L12) can be focused by the first focusing optical system (351) at positions spaced apart from each other in the processing direction (e.g., X direction) on the cutting line (15) on the processing object (1). When the power of the laser light (L) is P and the number of the plurality of first processing beams (L12) is n, the power of each of the plurality of first processing beams (L12) is P / n. The second beam splitter (342) can split the second processing beam (L21) into a plurality of second processing beams (L22) spaced apart in the processing direction (e.g., X direction). The plurality of second processing beams (L22) can be focused at positions spaced apart from each other in the processing direction (e.g., X direction) on the cutting line (15) on the processing target (1) by the second focusing optical system (352). Similarly, if the power of the laser light (L) is P and the number of the plurality of second processing beams (L22) is m, the power of each of the plurality of first processing beams (L12) is P / m. The optical structures of the first and second beam splitters (341)(342) are not particularly limited. For example, the first and second beam splitters (341)(342) can be implemented by various optical systems such as an imaging optical system, a polygon optical system, and an optical system using a diffractive optical element. The first and second condensing optical systems (351)(352) may include condensing lenses. The first and second condensing optical systems (351)(352) may also include a zoom lens unit for adjusting the size, for example, beam width, of the plurality of first and second processing beams (L12)(L22).

[0062] The control unit (400) controls the stage (100), the laser generator (200), and the optical system (300) to form a groove to be cut in the object to be processed (1), as described below. The control unit (400) may be provided with, for example, a processor, a memory, and an input means. A control program for controlling a laser processing device may be stored in the memory. A processing command including various parameters for forming a groove to be cut may be input through the input means. The processor may control the laser processing device to form the groove to be cut by driving the control program stored in the memory. The input means may be, for example, a host computer connected to the laser processing device, or may be a self-input means, such as a keyboard, provided in the laser processing device itself.

[0063] When the processing beam is focused on the object to be processed (1), a state in which a very high peak power is locally concentrated is formed by temporally and spatially compressing the beam near the focusing point. Then, the object to be processed (1) is locally melted and vaporized by the energy of the processing beam. For example, the relative position of the processing beam with respect to the object to be processed (1) is aligned so that the processing beam is positioned on the cutting line on the object to be processed (1), and the processing beam is relatively moved at least once in the processing direction (e.g., the X direction) with respect to the object to be processed (1), thereby forming a cutting groove extending in the X direction. The relative movement of the processing beam with respect to the object to be processed (1) in the processing direction can be implemented, for example, by moving the stage (100) on which the object to be processed (1) is mounted in the processing direction. Of course, the object to be processed (1) may be positioned at a fixed position and the processing beam may be moved in the processing direction.

[0064] FIG. 5 is a flowchart of a method for dividing a processing object according to an embodiment of the present disclosure. Referring to FIG. 5, the method for dividing a processing object according to the present disclosure may include a step (S10) of preparing a processing object (1), a step (S20) of shaping a laser light (L) into a processing beam, a step (S30) of forming a cutting groove that partially extends from a material layer to the inside of a substrate layer (11) while moving the processing beam in a processing direction with respect to the processing object (1), and a step (S40) of dividing the processing object along the cutting groove. Hereinafter, various embodiments of the method for dividing a processing object will be described.

[0065] Hereinafter, the terms U shape and V shape are used to describe the shape of the groove to be cut. The U shape refers to a shape in which the width changes little as the depth increases in a cross-section orthogonal to the machining direction (e.g., X direction). In other words, the U shape refers to a shape with a flat (non-pointed) lower surface and whose upper and lower widths are almost the same. However, the side surface of the U shape does not have to be a strictly depth direction (e.g., Z direction) surface. The V shape refers to a shape in which the width becomes narrower and has a pointed end as the depth increases in a cross-section orthogonal to the machining direction (e.g., X direction). In other words, the V shape is a shape with a pointed end and whose width becomes wider as it goes upward (e.g., +Z direction). The side surface of the V shape may be a plane inclined with respect to the depth direction (e.g., Z direction), or may be a curved surface with a changing inclination angle with respect to the Z direction.

[0066]

[0067] First embodiment

[0068] FIG. 6 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure. Referring to FIGS. 5 and 6, a first embodiment of the method for dividing a processing object will be described.

[0069]

[0070] [Step S10]

[0071] A machining target (1) is prepared. As described above, the machining target (1) includes a substrate layer (11) and at least one material layer formed on the upper surface of the substrate layer (11). As illustrated in FIG. 3, the at least one material layer may include a pattern layer (13) for forming a semiconductor element (12). As illustrated in FIG. 4, the at least one material layer may further include a covering layer (14) covering the pattern layer (13). The material layers illustrated in FIGS. 3 and 4 are exemplary, and the material layers are not limited to the pattern layer (13) and the covering layer (14). The machining target (1) may have three or more material layers formed on the upper surface of the substrate layer (11), as needed. The machining target (1) is mounted on, for example, a stage (100). In the following embodiments, the relative movement of the machining beam and the machining target (1) is assumed as the machining beam being positioned at a stationary position and the stage (100) being moved.

[0072] If the thickness of the substrate layer (11) is thicker than the thickness that can be divided by forming a groove to be cut and stretching using a stretching film, the thickness of the object to be processed (1) can be reduced by polishing the substrate layer (11) before forming the groove to be cut. Referring to Fig. 6, the step (S10) of preparing the object to be processed (1) may include a step (S11) of reducing the thickness of the object to be processed (1) by polishing the substrate layer (11) from the lower surface, and a step (S12) of bonding the object to be processed (1) to a stretching film after the polishing.

[0073] The polishing process can be performed by a mechanical polishing device. Fig. 7 is a drawing showing an example of a step of preparing a workpiece (1) including a polishing process. Referring to Fig. 7, the workpiece (1) is turned over so that the lower surface of the substrate layer (11) faces the polisher (501) and is placed on a holder of the polisher (not shown). Then, the polisher (501) is driven to polish the lower surface of the substrate layer (11) to reduce the thickness of the substrate layer (11). Here, the lower surface is the opposite surface to the upper surface where the material layer is formed. The thickness (T1) of the workpiece (1) after polishing may be, for example, 100 μm or less. As a non-limiting example, the thickness (T11) of the substrate layer (11) after polishing may be approximately 40 to 60 μm. After the polishing process is completed, the workpiece (1) is adhered to a stretched film (502). The lower surface of the substrate layer (11) is attached onto the stretched film (502). The processing target (1) can be mounted on the stage (100) of the laser processing device while being adhered to the stretch film (502).

[0074]

[0075] [Step S20]

[0076] The laser light is shaped into a processing beam. The control unit (400) controls the laser generator (200) to generate the laser light (L). The laser light (L) may be pulsed laser light having a pulse width of 1 μs or less, and may be, for example, ultrashort pulsed laser light having a pulse width of the nanosecond order, picosecond order, or femtosecond order. Such laser light (L) has very high focusing properties and can be focused up to the diffraction limit. The power of the laser light (L) may be appropriately determined for the processing beam to process the processing object (1). For example, the power of the laser light (L) may be determined by considering the power of each processing beam when the processing beam is divided into multiple processing beams as described below. For example, the laser light (L) may be femtosecond pulsed laser light in an ultraviolet wavelength band having a frequency of 2 MHz and a power of 10 W.

[0077] A method for dividing a processing object according to one embodiment uses two processing beams having different intensity profiles to form a groove to be cut. Each of the two processing beams includes a plurality of processing beams spaced apart from each other in a processing direction (e.g., X direction). To this end, a step (S20) of shaping laser light into a processing beam includes a step (S21) of dividing the processing beam into first and second processing beams (L11) (L21), and a step (S22) of dividing the first processing beam (L11) into a plurality of first processing beams (L12) and the second processing beam (L21) into a plurality of second processing beams (L22).

[0078] Referring to FIG. 1, the laser light (L) generated from the laser generator (200) is shaped by the optical system (300) and focused on the processing target (1). For example, the laser light (L) generated from the laser generator (200) is split into two processing beams (L1) (L2) by the beam splitter (310). Then, the processing beam (L1) is shaped into a first processing beam (L11) having a flat-top intensity profile by the beam shaper (320). The processing beam (L2) is shaped into a second processing beam (L21) having a Gaussian intensity profile by the beam shaper (320). The first processing beam (L11) is split into a plurality of first processing beams (L12) spaced apart from each other in the processing direction (e.g., X direction) by the first beam splitter (341). The second processing beam (L21) is split into a plurality of second processing beams (L22) spaced apart from each other in the processing direction (e.g., X direction) by the second light splitter (342).

[0079] The distance between the plurality of first processing beams (L12) may be, for example, 1 to 5 mm. For example, the distance between the plurality of first processing beams (L12) may be determined by considering the power and processing speed (i.e., relative movement speed) of each processing beam so that the next processing beam can reach the processing position before the processing byproduct generated by the preceding processing beam is completely solidified. If the distance between the plurality of first processing beams (L12) is too close, the processing quality may deteriorate due to the thermal effect of the preceding beam, and if it is too far, the number of branched processing beams may be too small due to the branching angle limit of the optical system (300). Taking this into account, the distance between the plurality of first processing beams (l12) may be about 1 to 5 mm, and for example, about 2.0 to 3.0 mm.

[0080] The beam width (spot size) of the plurality of first processing beams (L12) may be, for example, 20 μm or less. Here, the beam width refers to the beam width in the direction orthogonal to the processing direction (for example, the X direction). In addition, the beam width of the plurality of first processing beams (L12) refers to the beam width focused on the processing target (1) by the first focusing optical system (351). The number of the plurality of first processing beams (L12) may be, for example, three. However, the present invention is not limited thereto, and the number of the plurality of first processing beams (L12) may be two, four, or more, as needed. Since the beam width of the plurality of first processing beams (L12) having a flat-top intensity profile is relatively large compared to the plurality of second processing beams (L22) having a Gaussian intensity profile, the number of the plurality of first processing beams (L12) may be less than the number of the plurality of second processing beams (L22). The number of first processing beams (L12), the beam spacing, and the beam width can be appropriately determined to form a first cutting groove to be described later, taking into account the power of the laser light (L).

[0081] The distance between the plurality of second processing beams (L22) may be, for example, 1 to 5 mm. For example, the distance between the plurality of second processing beams (L22) may be determined by considering the power and processing speed (i.e., relative movement speed) of each processing beam so that the next processing beam can reach the processing position before the processing byproduct generated by the preceding processing beam is completely solidified. If the distance between the plurality of second processing beams (L22) is too close, the processing quality may deteriorate due to the thermal effect of the preceding beam, and if it is too far, the number of branched processing beams may be too small due to the branching angle limit of the optical system (300). Taking this into account, the distance between the plurality of second processing beams (L22) may be, for example, 1 to 5 mm, and for example, 2.0 to 3.0 mm.

[0082] The smaller the beam width (spot size) of the plurality of first processing beams (L12), the more advantageous it may be for forming the V-shaped second cutting groove described later. If the beam width of the plurality of second processing beams (L22) is large, the amount of debris or chipping may increase during processing. This is because, when the beam width is large, the beam quality of the outer region of the beam becomes lower than that of the central region. In addition, the smaller the beam width, the smaller the line width of the second cutting groove formed by processing, so that a sharper V-shaped second cutting groove can be formed. Taking this into account, the beam width of the plurality of second processing beams (L22) may be, for example, 20 μm or less. Here, the beam width is a beam width in a direction orthogonal to the processing direction (for example, the X direction). In addition, the beam width of the plurality of second processing beams (L22) refers to the beam width focused on the object (1) to be processed by the second focusing optical system (352). However, if the beam width is excessively small, the distance between the focusing optical system and the object (1) to be processed becomes short, and the focal length of the focusing optical system becomes short. Then, it is difficult to install a protective device to protect the focusing optical system from foreign substances generated during processing, and there is a possibility that the focusing optical system may be contaminated because the suction of foreign substances is not performed well. In addition, since the depth of field (DOF) of the focusing optical system becomes short, in order to prevent interference between the object (1) to be processed and the focusing optical system during the process of replacing the object (1) to be processed, it is necessary to move the focusing optical system or the entire optical system in the Z direction, for example, and then mount the object (1) to be processed on the stage (100), and then move the focusing optical system or the entire optical system in the Z direction again to the processing position. Therefore, this may be disadvantageous in terms of shortening the process time.

[0083] The number of the plurality of second processing beams (L22) may be greater than the number of the plurality of first processing beams (L12). For example, the number of the plurality of second processing beams (L22) may be, for example, five. However, the present invention is not limited thereto, and the number of the plurality of second processing beams (L22) may be four or less, or six or more. As the number of the plurality of second processing beams (L22) increases, the power of each second processing beam (L22) decreases. Therefore, the number, beam spacing, and beam width of the plurality of second processing beams (L22) may be appropriately determined to form the second cutting groove in consideration of the power of the laser light (L).

[0084]

[0085] [Step S30]

[0086] By processing a workpiece (1) using a processing beam, a cutting groove extending partially from a material layer to the inside of a substrate layer (11) is formed in the workpiece (1). A method for dividing a workpiece according to one embodiment may include a first processing step (S32) of forming a U-shaped first cutting groove in the workpiece (1) while moving a first processing beam (L12), for example, a plurality of first processing beams (L12), relative to the workpiece (1) at least once, and a second processing step (S34) of forming a V-shaped second cutting groove extending from a lower surface of the first cutting groove to the inside of the substrate layer (11) while moving a second processing beam (L22), for example, a plurality of second processing beams (L22), relative to the workpiece (1) at least once.

[0087] First, for example, the control unit (400) controls the attenuator (330) so that the power of the second processing beam (L21) becomes “0” (S31). Then, the second processing beam (L21) is turned off and the first processing beam (L11) is turned on. The first processing beam (L11) is split into a plurality of first processing beams (L12) by the first beam splitter (341), and each of the plurality of first processing beams (L12) is focused on the surface of the processing target (1) by the first focusing optical system (351) to have a predetermined beam width. Next, the first processing step (S32) is performed.

[0088] FIG. 8 is a drawing showing an example of the first processing step (S32). FIG. 8 shows a cross-sectional view and a plan view together. For example, in FIG. 8, the processing direction is the +X direction, and the relative movement of the first processing beam (L12) and the processing object (1) is implemented by driving the stage (100) to move the processing object (1). Therefore, when the processing direction is the +X direction, the processing object (1) is moved in the -X direction. In FIG. 8, the focused shape of the first processing beam (L12) is shown as a circle, but the focused shape of the first processing beam (L12) is not limited thereto. For example, the focused shape of the first processing beam (L12) may have various shapes such as an ellipse, a square, and a line beam. As described above, the first processing beam (L12) may have a flat-top type intensity profile. In FIG. 8, three first processing beams (L12) are employed as an example. Three first processing beams (l12) are arranged to be spaced apart from each other in the processing direction, and the mutual spacing distance between the plurality of first processing beams (L12), i.e., the arrangement interval (G1), satisfies the above-described condition. The beam width (W1) of each of the three first processing beams (l12) also satisfies the above-described condition.

[0089] The stage (100) is driven to align three first processing beams (L12) on the cutting line (15) of the processing object (1). Each of the three first processing beams (L12) is focused on the surface of the processing object (1) by the first focusing optical system (351), thereby forming three focusing points. Then, the three first processing beams (L12) are temporally and spatially compressed near the focusing points, thereby forming a state in which a very high peak power is locally concentrated. The processing object (1) is locally melted and vaporized by the energy of the three first processing beams, thereby forming a first cutting groove (Fig. 9: 21).

[0090] The first cutting groove (21) may be formed by one processing, or may be formed by multiple processing. Here, “one processing” may mean, for example, one processing in the +X direction, or may mean one reciprocating processing including one processing in the +X direction and one processing in the -X direction.

[0091] Fig. 9 shows an example of a process for forming a first cutting groove (21). Fig. 9 exemplarily shows a process for forming a first cutting groove (21) by one machining in the +X direction. Referring to Fig. 9, among three first machining beams (L12), the first beam (L12-1) that is the most advanced in the machining direction, the second beam (L12-2), and the third beam (L12-3) are sequentially irradiated onto the machining target (1). By the beam (L12-1), the machining target (1), for example, a material layer, is locally melted and evaporated, so that a concave U-shaped groove in the thickness direction from the upper surface of the machining target (1) begins to be formed, as shown in (a) of Fig. 9. Next, the second beam (L12-2) and the third beam (L12-3) are sequentially irradiated onto the workpiece (1), and the width and depth of the groove increase as shown in (b) and (c) of FIG. 9, and finally, a U-shaped first cutting groove (21) can be formed as shown in (c) of FIG. 9.

[0092] In the case where the first cutting groove (21) is formed through multiple processing, Fig. 9 can be understood as a drawing showing the process in which the width and depth of the groove gradually increase through multiple processing.

[0093] When a first cutting groove (21) is formed using a single processing beam with strong power, the occurrence of debris, burrs, etc. may increase, which may contaminate the surface of the processing target (1). In addition, the quality of the first cutting groove (21) may be deteriorated as the molten by-products are attached to the side wall of the first cutting groove (21) and solidified. According to the present embodiment, a plurality of first processing beams (L12) having divided powers, for example, three, are used to sequentially form and expand grooves to form the first cutting groove (21). Therefore, the occurrence of debris, burrs, etc. can be reduced. In addition, since the molten by-products attached to the side wall of the groove can be removed by the subsequent processing beam, the formation of a high-quality first cutting groove (21) is possible.

[0094] Fig. 10 shows examples of a first cutting groove (21). Referring to Fig. 10, the width (21W) of the first cutting groove (21) may be larger than the width of the second cutting groove described later. For example, the width (21W) of the first cutting groove (21) may be three times or more the width of the second cutting groove described later. In one embodiment, the width (21W) of the first cutting groove (2) may be approximately 40 μm. The first cutting groove (21) is for removing a material layer along the cutting line (15). However, the first cutting groove (21) does not strictly remove only the material layer along the cutting line (15). Accordingly, the formation range of the first cutting groove (21) in the thickness direction of the processing target (1), i.e., the Z direction, may cover a part of the material layer as shown in (a) of FIG. 10, the entire material layer as shown in (b) of FIG. 10, or the entire material layer and a part of the substrate layer (11) as shown in (c) of FIG. 10.

[0095] Next, the second processing step (S34) is performed. Before that, the control unit (400) controls the attenuator (330) so that the power of the first processing beam (L11) becomes “0” (S33). Then, the first processing beam (L11) is turned off and the second processing beam (L21) is turned on. The second processing beam (L21) is split into a plurality of second processing beams (L22) by the second beam splitter (342), and each of the plurality of second processing beams (L22) is focused on the surface of the processing object (1) by the second focusing optical system (352) to have a predetermined beam width.

[0096] Fig. 11 is a drawing showing an example of a secondary processing step (S34). Fig. 11 shows a cross-sectional view and a plan view together. Fig. 11 shows a case where secondary processing is performed in a state where a material layer is removed along a cutting line (15) to be cut by primary processing. For example, in Fig. 11, the processing direction is the +X direction, and the relative movement of the second processing beam (L22) and the processing object (1) is implemented by driving the stage (100) to move the processing object (1). Therefore, when the processing direction is the +X direction, the processing object (1) is moved in the -X direction. In Fig. 11, the focused shape of the second processing beam (L22) is shown as a circle, but the focused shape of the second processing beam (L22) is not limited thereto. For example, the focused shape of the second processing beam (L22) may have various shapes such as an ellipse, a square, a line beam, etc. As described above, the second processing beam (L22) has a Gaussian intensity profile. As an example, five second processing beams (L22) are illustrated in Fig. 11. The five second processing beams (L22) are arranged to be spaced apart from each other in the processing direction, and the mutual spacing distance between the plurality of second processing beams (L22), i.e., the array interval (G2), satisfies the above-described condition. The beam width (W2) of each of the five second processing beams (L22) also satisfies the above-described condition.

[0097] The second cutting groove (22) may be formed by one processing, or may be formed by multiple processing. Here, "one processing" may mean, for example, one processing in the +X direction, or may mean one reciprocating processing including one processing in the +X direction and one processing in the -X direction.

[0098] Fig. 12 shows an example of a process for forming a second cutting groove (22). Fig. 12 exemplarily shows a process for forming a second cutting groove (22) by one machining in the +X direction. Referring to Fig. 12, among five second machining beams (L22), the first beam (L22-1) which is the most advanced in the machining direction, and the second to fifth beams (L22-2, L22-3, L22-4, L22-5) are sequentially irradiated onto the machining target (1). By the first beam (L22-1), the machining target (1), for example, the material layer (if remaining in the first cutting groove (21)) and the substrate layer (11) are locally melted and evaporated, so that a concave V-shaped groove in the thickness direction begins to be formed from the lower surface of the first cutting groove (21), as shown in Fig. 12 (a). Next, the second to fifth beams (L22-2, L22-3, L22-4, L22-5) are sequentially irradiated onto the workpiece (1), and the width and depth of the groove increase as shown in (b), (c), (d), and (e) of FIG. 12, and finally, as shown in (e) of FIG. 12, a V-shaped second cutting groove (22) partially extending from the lower surface of the first cutting groove (21) into the inside of the substrate layer (11) can be formed.

[0099] In the case where the second cutting groove (22) is formed through multiple processing, Fig. 12 can be understood as a drawing showing the process in which the width and depth of the groove gradually increase through multiple processing.

[0100] According to the present embodiment, a plurality of second processing beams (L22), for example, five, having divided powers are used to sequentially form and expand grooves to form a second cutting groove (22). Accordingly, the occurrence of debris, burrs, etc. can be reduced. In addition, since molten byproducts attached to the side walls of the grooves can be removed by the subsequent processing beams, formation of a high-quality second cutting groove (22) is possible.

[0101] Fig. 13 is a detailed view of an example of a first cutting groove (21) and a second cutting groove (22). Referring to Fig. 13, as described above, a cutting groove (20) including first and second cutting grooves (21) (22) that partially extend from the material layer to the substrate layer (11) is formed through the first and second processing. The width (22W) of the second cutting groove (22) is smaller than the width (21W) of the first cutting groove (21). As described above, the width (21W) of the first cutting groove (21) may be three times or more the width (22W) of the second cutting groove (22). For example, the width (21W) of the first cutting groove (21) may be about 40 μm.

[0102] As an example, the width (22W) of the second cutting groove (22) may be 10 μm or less. In other words, the distance (22hW) from the reference line (RL) extending in the thickness direction of the workpiece (1), i.e., the Z direction, from the pointed end (22t) of the second cutting groove (22) to the upper edge (22e) of the second cutting groove (22) may be 5 μm or less.

[0103] As an example, the second cutting groove (22) may be formed so that the pointed end (22t) is positioned at a range of 30 to 80% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11). Here, the thickness (11T) of the substrate layer (11) refers to the thickness after the aforementioned polishing process. However, the range of 30 to 80% is not absolute, and depending on the material of the substrate layer (11), the second cutting groove (22) may be positioned at a range of more than 80% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11).

[0104] As an example, the distance between the sharp end (22t) of the second cutting groove (22) and the lower surface of the substrate layer (11) may be approximately 5 to 10 μm. Here, the thickness (11T) of the substrate layer (11) refers to the thickness after the aforementioned polishing process. Accordingly, in the elongation process described later, the processing target (1) can be divided with high quality by cracks generated from the sharp end (22t) of the second cutting groove (22).

[0105] As an example, the depth (22D) of the second cutting groove (22) may be at least 2.5 times the width (22W) of the upper edge (22e) of the second cutting groove (22). As a result, a high-quality second cutting groove (22) having a small inclination angle of the slope with respect to the reference line (RL) can be realized.

[0106] Although Fig. 13 illustrates that the slope of the second cutting groove (22) is a curved surface with a varying inclination angle, this is not limited thereto. The slope of the second cutting groove (22) may also be a plane with a constant inclination angle.

[0107] The power of the laser light (L) in the first processing step (S32) may be the same as the power of the laser light (L) in the second processing step (S34). However, this is not limited thereto. For example, at least one of the power, frequency, and processing speed of the laser light (L) in the first processing step (S32) and the second processing step (S34) may be different. The processing speed is the relative movement speed of the processing beam with respect to the processing target (1). The power, frequency, and processing speed of the laser light (L) in the first processing step (S32) and the second processing step (S34) may be appropriately adjusted so as to obtain high-quality first and second cutting-target grooves (21)(22).

[0108]

[0109] [Step S40]

[0110] Next, a step (S40) of dividing the workpiece (1) along the cutting groove (20) is performed. Fig. 14 is a drawing showing an example of a step of dividing the workpiece. Referring to Figs. 6 and 14, the method for dividing the workpiece of the present embodiment may include a step (S41) of forming a crack (CR) from the pointed end (22t) of the second cutting groove (22) to the lower surface of the substrate layer (11) by stretching the stretching film (502).

[0111] For example, the processing target (1) is in a state where its lower surface is attached to a stretched film (502). In this state, the stretched film (502) is stretched in a direction perpendicular to the cutting groove (20). For example, although not illustrated in the drawing, the process of stretching the stretched film (502) can be performed by fixing the edge of the stretched film (502) and pushing upward with a pusher (not illustrated) from the lower portion of the stretched film (502). As a result, the stretched film (502) is stretched, for example, along the XY plane, and a tensile force in a direction perpendicular to the cutting groove (20) is applied to the processing target (1). Then, a crack (CR) is generated from the sharp end (22t) of the second cutting groove (22), and the crack (CR) extends to the lower surface of the substrate layer (11). In this way, the object to be processed (1) can be divided based on the groove (20) to be cut. Although not shown in the drawing, by performing the cooling process while the object to be processed (1) is adhered to the stretching film (502) before performing the stretching process, the stretching film (502) can also be divided together with the object to be processed (1) by the stretching process.

[0112]

[0113] Second embodiment

[0114] FIG. 15 is a flowchart of a method for dividing a processing object according to an embodiment of the present disclosure. In the first embodiment of the method for dividing a processing object described with reference to FIG. 6 described above, in the step (S10) of preparing a processing object (1), the lower surface of the substrate layer (11) is polished to reduce the thickness of the processing object (1), and a cutting groove (20) including first and second cutting grooves (21) (22) is formed, and then the processing object (1) is divided using the cutting groove (20) as a starting point through an elongation process. In contrast, the method for dividing a processing object according to the second embodiment illustrated in FIG. 15 differs from the method for dividing a processing object according to the second embodiment in that the substrate layer (11) is not polished in the step of preparing a processing object (1), and after a cutting groove (20) including first and second cutting grooves (21) (22) is formed, the processing object (1) is divided using the cutting groove (20) as a starting point through a polishing process. In the following, descriptions overlapping with those of the embodiment illustrated in Fig. 6 will be omitted, and differences will be mainly explained.

[0115]

[0116] [Step S10a]

[0117] A processing object (1) is prepared. As described above, the processing object (1) includes a substrate layer (11) and at least one material layer formed on the upper surface of the substrate layer (11). As illustrated in FIG. 3, the at least one material layer may include a pattern layer (13) for forming a semiconductor element (12). As illustrated in FIG. 4, the at least one material layer may further include a covering layer (14) covering the pattern layer (13). The material layers illustrated in FIGS. 3 and 4 are exemplary, and the material layers are not limited to the pattern layer (13) and the covering layer (14). The processing object (1) may have three or more material layers formed on the upper surface of the substrate layer (11), as needed. The step (10a) of preparing the processing object (1) is identical to the step (S10) of preparing the processing object (1) described above in that the polishing process and the process of bonding the processing object (1) are omitted. Therefore, the description of step S10 of the first embodiment, excluding the polishing process and the bonding process to the stretched film, applies equally to step S10a.

[0118]

[0119] [Step S20a]

[0120] A method for dividing a processing object according to one embodiment uses two processing beams having different intensity profiles to form a groove to be cut. Each of the two processing beams includes a plurality of processing beams spaced apart from each other in a processing direction (e.g., X direction). To this end, a step (S20a) of shaping laser light into a processing beam includes a step (S21) of dividing the processing beam into first and second processing beams (L12) (L22), and a step (S22) of dividing the first processing beam (L12) into a plurality of first processing beams (L13) and the second processing beam (L22) into a plurality of second processing beams (L23). Step S20a is the same as step S20 of the first embodiment described above. Therefore, the description of step S20 of the first embodiment applies equally to step S20a of the present embodiment.

[0121]

[0122] [Step S30a]

[0123] By processing a workpiece (1) using a processing beam, a cutting groove extending partially from a material layer to the inside of a substrate layer (11) is formed in the workpiece (1). A method for dividing a workpiece according to one embodiment may include a first processing step (S32) of forming a U-shaped first cutting groove (21) in the workpiece (1) while relatively moving a first processing beam (L12), for example, a plurality of first processing beams (L12), at least once, and a second processing step (S34) of forming a V-shaped second cutting groove (22) extending from a lower surface of the first cutting groove (21) to the inside of the substrate layer (11) while relatively moving a second processing beam (L22), for example, a plurality of second processing beams (L22), at least once. Step S30a is the same as step S30 of the first embodiment described above. Accordingly, the description of step S30 of the first embodiment applies equally to step S30a of the present embodiment. However, in forming the second cutting groove (22), there is a difference in the depth of the second cutting groove (22), as follows.

[0124] Fig. 16 is a detailed view of an example of a first cutting groove (21) and a second cutting groove (22). Referring to Fig. 16, as described above, a cutting groove (20) including first and second cutting grooves (21) (22) that partially extend from the material layer to the substrate layer (11) is formed through the first and second processing. The width (22W) of the second cutting groove (22) is smaller than the width (21W) of the first cutting groove (21). As described above, the width (21W) of the first cutting groove (21) may be three times or more the width (22W) of the second cutting groove (22). For example, the width (21W) of the first cutting groove (21) may be about 40 μm.

[0125] As an example, the width (22W) of the second cutting groove (22) may be 10 μm or less. In other words, the distance (22hW) from the reference line (RL) extending in the thickness direction of the workpiece (1), i.e., the Z direction, from the pointed end (22t) of the second cutting groove (22) to the upper edge (22e) of the second cutting groove (22) may be 5 μm or less.

[0126] Since the processing target (1) has not undergone a polishing process to reduce the thickness, the thickness (11T2) of the substrate layer (11) is greater than the thickness (11T) of the substrate layer (11) in the embodiment illustrated in Fig. 13. Therefore, the depth (22D) of the second cutting groove (22) can be determined in consideration of the polishing amount of the polishing process for division described later. In one embodiment, the second cutting groove (22) can be formed so that the pointed end (22t) is positioned in a range of 30 to 80% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11). However, the range of 30~80% is not absolute, and depending on the material of the substrate layer (11), the amount of polishing in the polishing process, etc., the second cutting groove (22) may be positioned at a position where the sharp end (22t) does not exceed 30% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11), or may be positioned at a position exceeding 80%. The depth (22D) of the second cutting groove (22) may be 2.5 times or more the width (22W) of the upper edge (22e) of the second cutting groove (22), whereby a high-quality second cutting groove (22) having a small inclination angle of the slope with respect to the reference line (RL) can be implemented.

[0127] Although Fig. 16 illustrates that the slope of the second cutting groove (22) is a curved surface with a changing inclination angle, this is not limited to this. The slope of the second cutting groove (22) may also be a plane with a constant inclination angle.

[0128]

[0129] [Step S40a]

[0130] Next, a step (S40a) of dividing the workpiece (1) along the cutting groove (20) is performed. Fig. 17 is a drawing showing an example of a step of dividing the workpiece. Referring to Figs. 15 and 17, the method for dividing the workpiece of the present embodiment may include a step (S42) of polishing the lower surface of the substrate layer (11) at least to a position adjacent to the cutting groove (20), that is, the pointed end (22t) of the second cutting groove (22).

[0131] The polishing process can be performed, for example, by a mechanical polishing device. As illustrated in (a) of Fig. 17, the workpiece (1) is turned over so that the lower surface of the substrate layer (11) faces the polisher (501) and is placed on a holder of the polisher (not illustrated). Then, the polisher (501) is driven to polish the lower surface of the substrate layer (11) to reduce the thickness of the substrate layer (11). Polishing is performed from the lower surface of the substrate layer (11) to the vicinity of the pointed end (22t) of the second cutting groove (22). As the thickness of the substrate layer (11) decreases and the lower surface of the substrate layer (11) approaches the sharp end (22t) of the second cutting groove (22), a crack (CR) is generated from the sharp end (22t) of the second cutting groove (22) as shown in (b) of FIG. 17, and the crack (CR) can extend to the lower surface of the substrate layer (11). As a result, the object to be processed (1) can be divided based on the cutting groove (20). As shown in (c) of FIG. 17, polishing can be performed up to the sharp end (22t) of the second cutting groove (22). As a result, the object to be processed (1) can be divided based on the cutting groove (20).

[0132] The first and second embodiments described above relate to a method for forming a cutting groove (20) by sequentially forming a first cutting groove (21) and a second cutting groove (22) by first and second processing using two processing beams having different intensity distributions, respectively, and dividing a processing target (1) based on the cutting groove (20). However, the present invention is not limited thereto, and a cutting groove that partially extends from a material layer to the inside of a substrate layer (11) may be formed by using a processing beam having a Gaussian intensity profile or a plurality of processing beams having Gaussian intensity profiles.

[0133]

[0134] Third embodiment

[0135] Fig. 18 is a flowchart of a method for dividing a processing object according to one embodiment of the present disclosure. Referring to Fig. 18, a third embodiment of the method for dividing a processing object will be described. The method for dividing a processing object according to this embodiment differs from the first embodiment described above in that a cutting groove extending partially from the material layer to the interior of the substrate layer (11) is formed using a processing beam having a Gaussian intensity distribution. The differences will be mainly described below.

[0136]

[0137] [Step S10b]

[0138] A processing object (1) is prepared. The processing object (1) is mounted on a stage (100) after a polishing process to reduce the thickness and an adhesion process to a stretched film (502). The step (S10b) of preparing the processing object (1) is identical to the step (S10) of preparing the processing object (1) of the first embodiment. Therefore, the description of step S10 of the first embodiment applies equally to step S10b.

[0139]

[0140] [Step S20b]

[0141] A method for dividing a processing object according to one embodiment uses a processing beam (L21) having a Gaussian intensity profile to form a groove to be cut. The processing beam (L21) may include a plurality of processing beams (L22) spaced apart from each other in a processing direction (e.g., X direction). To this end, the step (S20b) of shaping the processing beam with laser light includes a step (S23) of shaping the laser light (L) into a processing beam (L21) having a Gaussian intensity profile, and a step (S24) of dividing the processing beam (L21) into a plurality of processing beams (L22).

[0142] The control unit (400) controls the laser generator (200) to generate laser light (L). The laser light (L) may be pulsed laser light having a pulse width of 1 μs or less, and may be, for example, ultrashort pulsed laser light having a pulse width of the nanosecond order, picosecond order, or femtosecond order. Such laser light (L) has very high focusing properties and can be focused up to the diffraction limit. For example, the laser light (L) of the present embodiment may be femtosecond pulsed laser light in the ultraviolet wavelength band having a frequency of 2 MHz and a power of 10 W.

[0143] In forming the processing beam (L12), the optical system (300) illustrated in FIG. 1 can be utilized. For example, referring to FIG. 1, the laser light (L) generated from the laser generator (200) is shaped by the optical system (300) and focused on the processing target (1). For example, the laser light (L) generated from the laser generator (200) is split into two processing beams (L1) (L2) by the beam splitter (310). Then, the processing beam (L1) is shaped by the beam shaper (320) into a first processing beam (L11) having a flat-top intensity profile. The processing beam (L2) is shaped by the beam shaper (320) into a second processing beam (L21) having a Gaussian intensity profile. At this stage, the intensity of the first processing beam (L11) is adjusted to “0” by the attenuator (330). Therefore, the first processing beam (L11) is not used for processing in the step after the attenuator (330). The second processing beam (L21) is split into a plurality of second processing beams (L22) spaced apart from each other in the processing direction (e.g., X direction) by the second beam splitter (342). Hereinafter, the second processing beam (L21) is referred to as the processing beam (L21), and the plurality of second processing beams (L22) are referred to as the plurality of processing beams (L22).

[0144] As an example, in explaining the process of forming the processing beam (L12), the beam splitter (310), the attenuator (320), the first beam splitter (341), and the first focusing optical system (351) in FIG. 1 may be considered as absent. In this case, the second beam splitter (342) and the second focusing optical system (352) may simply be referred to as the beam splitter (342) and the focusing optical system (352), and the second processing beam (L2) (L21) (L22) may be referred to as the processing beam (L2) (L21) (L22). For example, the laser light (L) generated from the laser generator (200) is used for processing as the processing beam (L2). The processing beam (L2) is shaped into the processing beam (L21) having a Gaussian intensity profile by the beam shaper (320). The processing beam (L21) is split into a plurality of processing beams (L22) spaced apart from each other in the processing direction (e.g., X direction) by a beam splitter (342).

[0145] The distance between the plurality of processing beams (L22) may be, for example, 1 to 5 mm. For example, the distance between the plurality of processing beams (L22) may be determined by considering the power and processing speed (i.e., relative movement speed) of each processing beam so that the next processing beam can reach the processing position before the processing byproduct generated by the preceding processing beam is completely solidified. If the distance between the plurality of processing beams (L22) is too close, the processing quality may deteriorate due to the thermal effect of the preceding beam, and if it is too far, the number of branched processing beams may be too small due to the branching angle limit of the optical system (300). Taking this into account, the distance between the plurality of processing beams (L22) may be, for example, 1 to 5 mm, and for example, 2.0 to 3.0 mm.

[0146] The smaller the beam width of the plurality of processing beams (L22), the more advantageous it may be for forming a V-shaped cutting groove to be described later. If the beam width of the plurality of processing beams (L22) is large, the amount of debris or chipping may increase during processing. This is because, when the beam width is large, the beam quality of the outer region of the beam becomes lower than that of the central region. In addition, the smaller the beam width, the smaller the line width of the second cutting groove formed by processing, so that a sharper V-shaped cutting groove can be formed. Taking this into account, the beam width of the plurality of processing beams (L22) may be, for example, 20 μm or less. Here, the beam width refers to the beam width in the direction orthogonal to the processing direction (for example, the X direction). In addition, the beam width of the plurality of processing beams (L22) refers to the beam width focused on the processing target (1) by the second focusing optical system (352). However, if the beam width is too small, the distance between the focusing optical system and the object to be processed (1) becomes short, and the focal length of the focusing optical system becomes short. Then, it is difficult to install a protective device to protect the focusing optical system from foreign substances generated during processing, and there is a possibility that the focusing optical system may be contaminated because the suction of foreign substances is not performed well. In addition, since the depth of field (DOF) of the focusing optical system becomes short, in the process of replacing the object to be processed (1), in order to prevent interference between the object to be processed (1) and the focusing optical system, it is necessary to move the focusing optical system or the entire optical system in the Z direction, for example, and then mount the object to be processed (1) on the stage (100), and then move the focusing optical system or the entire optical system in the Z direction again to the processing position. Therefore, this may be disadvantageous in terms of shortening the process time.

[0147] For example, the number of the plurality of processing beams (L22) may be, for example, five. However, the present invention is not limited thereto, and the number of the plurality of processing beams (L22) may be four or less, or six or more. As the number of the plurality of processing beams (L22) increases, the power of each processing beam (L22) decreases. Therefore, the number of the plurality of processing beams (L22), the beam spacing, and the beam width may be appropriately determined to form a groove to be cut in consideration of the power of the laser light (L).

[0148]

[0149] [Step S30b]

[0150] By processing the workpiece (1) using a processing beam (L21), a cutting groove that partially extends from the material layer to the inside of the substrate layer (11) is formed in the workpiece (1).

[0151] The processing beam (L21) is split into a plurality of processing beams (L22) by a beam splitter (342), and each of the plurality of processing beams (L22) is focused to have a predetermined beam width on the surface of the processing target (1) by a focusing optical system (352). The arrangement of a plurality of, for example, five, processing beams (L22) on the processing target (1) is the same as in Fig. 11 and the corresponding description. The groove to be cut can be formed by one processing, or can be formed by multiple processing. Here, “one processing” can mean, for example, one processing in the +X direction, or can mean one round-trip processing including one processing in the +X direction and one processing in the -X direction.

[0152] Among the five second processing beams (L22), the first beam (L22-1) that is the most advanced in the processing direction and the second to fifth beams (L22-2, L22-3, L22-4, L22-5) are sequentially irradiated onto the processing target (1). By processing once or multiple times, a V-shaped cutting groove (30) that partially extends from the material layer to the inside of the substrate layer (11) is formed in the processing target (1), as illustrated in FIG. 19. Referring to FIG. 19, the cutting groove (30) may include a first portion (30a) and a second portion (30b). The first portion (30a) is a portion formed in the material layer, and the second portion (30b) is a portion that extends from the first portion (30a) to the inside of the substrate layer (11). Since the material layer and the substrate layer (11) have different material compositions, the width (30aW) of the upper edge of the first portion (30a) formed on the material layer is generally larger than the width (30bW) of the upper edge (30e) of the second portion (30b). Since the processing beam (L22) has a Gaussian intensity profile, the cutting groove (30) including the first portion (30a) and the second portion (30b) has an overall V-shape.

[0153] In Fig. 19, the groove (30) to be cut is depicted as having no steps overall, and the slope of the groove (30) to be cut is depicted as a curved surface with a changing inclination angle. However, this is not limited thereto, and for example, in Fig. 19, the first part (30a) and the second part (30b) may have a discontinuous shape (in other words, a shape in which a step exists between the first part (30a) and the second part (30b). The slope of the groove (30) to be cut may also be a plane having a constant inclination angle.

[0154] As an example, the width (30bW) of the second portion (30b) of the groove (30) to be cut may be 10 μm or less. In other words, the distance (30bhW) from the reference line (RL) extending in the thickness direction of the workpiece (1), i.e., the Z direction, from the pointed end (30t) of the second portion (30b) of the groove (30) to the upper edge (30e) of the second portion (30b) of the groove (30) to be cut may be 5 μm or less.

[0155] As an example, the groove (30) to be cut may be formed so that the pointed end (22t) is positioned at a range of 30 to 80% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11). Here, the thickness (11T) of the substrate layer (11) refers to the thickness after the aforementioned polishing process. However, the range of 30 to 80% is not absolute, and depending on the material of the substrate layer (11), the groove (30) to be cut may be positioned at a range of more than 80% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11).

[0156] As an example, the depth (30D) of the cutting groove (30) may be at least 2.5 times the width (30aW) of the upper edge of the first portion (30a) of the cutting groove (30). As a result, a high-quality cutting groove (30) having a small inclination angle of the slope with respect to the reference line (RL) can be realized.

[0157] As an example, the distance between the sharp end (30t) of the groove (30) to be cut and the lower surface of the substrate layer (11) may be approximately 5 to 10 μm. Here, the thickness (11T) of the substrate layer (11) refers to the thickness after the polishing process described above. Accordingly, the workpiece (1) can be split with high quality by cracks generated from the sharp end (30t) of the groove (30) to be cut in the elongation process described later.

[0158]

[0159] [Step S40b]

[0160] Next, a step (S40b) of dividing the object to be processed (1) along the groove (30) to be cut by a stretching process is performed. Step S40b is the same as step S41 of the first embodiment described above, except that the object to be processed (1) in which the groove (30) to be cut is formed is applied. Therefore, the description regarding step S41 of the first embodiment applies equally to step S40b of the present embodiment. When the stretching film (502) is stretched, a crack (CR) may be formed from the sharp end (30t) of the groove (30) to be cut to the lower surface of the substrate layer (11). As the crack (CR) extends to the lower surface of the substrate layer (11), the object to be processed (1) may be divided based on the groove (30) to be cut. Although not shown in the drawing, by performing the cooling process while the object to be processed (1) is adhered to the stretching film (502) before performing the stretching process, the stretching film (502) can also be divided together with the object to be processed (1) by the stretching process.

[0161]

[0162] Fourth embodiment

[0163] FIG. 20 is a flowchart of a method for dividing a processing object according to an embodiment of the present disclosure. In the embodiment of the method for dividing a processing object described with reference to FIG. 18 described above, in the step (S10b) of preparing a processing object (1), the lower surface of the substrate layer (11) is polished to reduce the thickness of the processing object (1), and a cutting groove (30) is formed, and then the processing object (1) is divided using the cutting groove (30) as a starting point through an elongation process. In contrast, the method for dividing a processing object according to the embodiment illustrated in FIG. 20 differs from the method for dividing a processing object according to the embodiment illustrated in FIG. 20 in that the substrate layer (11) is not polished in the step of preparing the processing object (1), and after the cutting groove (30) is formed, the processing object (1) is divided using the cutting groove (30) as a starting point through a polishing process. Hereinafter, any description overlapping with that of the embodiment illustrated in FIG. 20 will be omitted, and the differences will be mainly described.

[0164]

[0165] [Step S10c]

[0166] A processing object (1) is prepared. The step (10c) of preparing the processing object (1) differs from the step (S10) of preparing the processing object (1) of the first embodiment in that the polishing process and the process of bonding the processing object (1) are omitted. Therefore, the description of step S10 of the first embodiment, excluding the polishing process and the process of bonding the processing object (1), applies equally to step S10c.

[0167]

[0168] [Step S20c]

[0169] According to one embodiment, a method for dividing a processing object uses a processing beam (L21) having a Gaussian intensity profile to form a groove to be cut. The processing beam (L21) may include a plurality of processing beams (L22) spaced apart from each other in a processing direction (e.g., X direction). To this end, the step (S20b) of shaping the processing beam with laser light includes a step (S23) of shaping the laser light (L) into a processing beam (L21) having a Gaussian intensity profile, and a step (S24) of dividing the processing beam (L21) into a plurality of processing beams (L22). Step S20c is the same as step S20b of the third embodiment described above. Therefore, the description of step S20b of the third embodiment applies equally to step S20c of the present embodiment.

[0170]

[0171] [Step S30c]

[0172] By processing the object to be processed (1) using a plurality of processing beams (L22), a cutting groove (30) that partially extends from the material layer to the inside of the substrate layer (11) is formed in the object to be processed (1). Step S30c is the same as step S30b of the third embodiment described above. Therefore, the description of step S30b of the third embodiment applies equally to step S30c of the present embodiment. However, in forming the cutting groove (30), there is a difference as follows with respect to the depth of the cutting groove (30).

[0173] Fig. 21 is a detailed drawing of an example of a cutting groove (30). Referring to Fig. 21, as described above, a cutting groove (30) that partially extends from the material layer to the substrate layer (11) is formed by a processing beam (L22) having a Gaussian intensity profile. As described above, the cutting groove (30) may include a first portion (30a) and a second portion (30b). The width (30aW) of the upper edge of the first portion (30b) is larger than the width (30bW) of the upper edge (30e) of the second portion (30b). Since the processing beam (L22) has a Gaussian intensity profile, the first portion (30a) and the second portion (30b) have a V-shape, and the cutting groove (30) has a V-shape overall.

[0174] In Fig. 21, the groove (30) to be cut is depicted as having no steps overall, and the slope of the groove (30) to be cut is depicted as a curved surface with a changing inclination angle. However, this is not limited thereto, and for example, in Fig. 21, the first part (30a) and the second part (30b) may have a discontinuous shape (in other words, a shape in which a step exists between the first part (30a) and the second part (30b). The slope of the groove (30) to be cut may also be a plane with a constant inclination angle.

[0175] As an example, the width (30bW) of the second portion (30b) of the groove (30) to be cut may be 10 μm or less. In other words, the distance (30bhW) from the reference line (RL) extending in the thickness direction of the workpiece (1), i.e., the Z direction, from the pointed end (30t) of the second portion (30b) of the groove (30) to the upper edge (30e) of the second portion (30b) of the groove (30) to be cut may be 5 μm or less.

[0176] Since the workpiece (1) has not undergone a polishing process to reduce the thickness, the thickness (11T2) of the substrate layer (11) is greater than the thickness (11T) of the substrate layer (11) in the embodiment illustrated in Fig. 19. Therefore, the depth of the groove (30) to be cut can be determined in consideration of the polishing amount of the polishing process for division described later. In one embodiment, the groove (30) to be cut can be formed such that the pointed end (30t) is positioned within a range of 30 to 80% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11). However, the range of 30 to 80% is not absolute, and depending on the material of the substrate layer (11), the amount of polishing in the polishing process, etc., the cutting groove (30) may be positioned at a position where the sharp end (30t) does not exceed 30% of the thickness (11T) of the substrate layer (11) from the upper surface of the substrate layer (11), or may be positioned at a position exceeding 80%. The depth (30D) of the cutting groove (30) may be 2.5 times or more the width (30bW) of the upper edge of the first portion (30a) of the cutting groove (30), whereby a high-quality second cutting groove (22) having a small inclination angle of the slope with respect to the reference line (RL) can be implemented.

[0177]

[0178] [Step S40c]

[0179] Next, a step (S40c) of dividing the workpiece (1) along the groove (30) to be cut is performed. Fig. 22 is a drawing showing an example of a step of dividing the workpiece. The method for dividing the workpiece of the present embodiment may include a step (S40d) of polishing the lower surface of the substrate layer (11) at least to a position adjacent to the sharp end (22t) of the groove (30) to be cut.

[0180] The polishing process can be performed, for example, by a mechanical polishing device. As illustrated in (a) of Fig. 22, the workpiece (1) is turned over so that the lower surface of the substrate layer (11) faces the polisher (501) and is placed on a holder of the polisher (not illustrated). Then, the polisher (501) is driven to polish the lower surface of the substrate layer (11) to reduce the thickness of the substrate layer (11). Polishing is performed from the lower surface of the substrate layer (11) to the vicinity of the pointed end (30t) of the groove (30) to be cut. As the thickness of the substrate layer (11) decreases and the lower surface of the substrate layer (11) approaches the sharp end (30t) of the groove (30) to be cut, a crack (CR) is generated from the sharp end (22t) of the groove (30) to be cut, as shown in (b) of FIG. 22, and the crack (CR) can extend to the lower surface of the substrate layer (11). As a result, the object to be processed (1) can be divided based on the groove (30) to be cut. As shown in (c) of FIG. 22, polishing can be performed up to the sharp end (30t) of the groove (22) to be cut. As a result, the object to be processed (1) can be divided based on the groove (20) to be cut.

[0181] Although embodiments of the present invention have been described above, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible.

Claims

1. A step of preparing a processing object including a substrate layer and at least one material layer formed on the upper surface of the substrate layer; A step of shaping laser light into a processing beam; A step of forming a cutting groove that partially extends from the material layer to the inside of the substrate layer while moving the processing beam relative to the processing object at least once in the processing direction; A step of dividing the workpiece along the cutting groove; A method for dividing a workpiece, wherein in at least one of the one or more relative movements in the step of forming the cutting groove, the workpiece beam has a Gaussian intensity profile, and the cutting groove is formed in a shape in which the width becomes narrower as the depth increases in a cross-section perpendicular to the workpiece direction and has a sharp end by the workpiece beam having the Gaussian intensity profile.

2. In paragraph 1, A method for dividing a processing object using the above laser light as a pulse laser light having a pulse width of 1 ㎲ or less.

3. In paragraph 1, The above-mentioned processing beam includes a first processing beam having a flat-top intensity profile and a second processing beam having a Gaussian intensity profile, The step of forming the above-mentioned cutting groove is: A first processing step of forming a first cutting groove having a flat lower surface in a cross-section perpendicular to the processing direction on the processing object while relatively moving the first processing beam at least once along the cutting line; A method for dividing a workpiece, comprising: a second processing step of forming a second cutting groove having a shape that becomes narrower as the depth increases and has a sharp end in a cross-section perpendicular to the processing direction extending from the lower surface of the first cutting groove into the inside of the substrate layer while relatively moving the second processing beam at least once along the cutting line; 4. In paragraph 3, A method for dividing a processing object, wherein the formation range of the first cutting groove in the thickness direction of the processing object is formed as one range among a part of the material layer, the entire material layer, and the entire material layer and a part of the substrate layer.

5. In paragraph 3, A method for dividing a workpiece, wherein the width of the second cutting groove is smaller than the width of the first cutting groove.

6. In paragraph 3, A method for dividing a workpiece, wherein the width of the first cutting groove is at least three times the width of the second cutting groove.

7. In paragraph 3, A method for dividing a workpiece, wherein the depth of the second cutting groove is at least 2.5 times the width of the upper edge of the second cutting groove.

8. In paragraph 3, A method for dividing a processing object, wherein the distance from a reference line extending in the thickness direction of the processing object from the pointed end of the second cutting groove to the upper edge of the second cutting groove is 5 μm or less.

9. In paragraph 3, The first processing beam includes a plurality of first processing beams spaced apart from each other in the processing direction, The second processing beam includes a plurality of second processing beams spaced apart from each other in the processing direction, A method for dividing a processing object, wherein the number of the plurality of first processing beams is less than the number of the plurality of second processing beams.

10. In paragraph 3, The second processing beam includes a plurality of second processing beams spaced apart from each other in the processing direction, A method for dividing a processing object in which the spot size of the plurality of second processing beams is 20㎛ or less.

11. In paragraph 10, A method for dividing a processing object in which the spacing between the plurality of second processing beams is 1 to 5 mm.

12. In paragraph 1, The step of preparing the above processing target is: A step of reducing the thickness of the processing object by polishing the lower surface of the substrate layer; and A step of adhering the above-mentioned processing object onto a stretched film; The step of dividing the above processing object is: A method for dividing a processing object, comprising: a step of stretching the stretching film to form a crack from a sharp end of the groove to be cut to the lower surface of the substrate layer.

13. In paragraph 12, A method for dividing a processing object, wherein the sharp end of the groove to be cut is located within a range of 5 to 10 μm from the lower surface of the substrate layer, based on the processing object after polishing.

14. In paragraph 12, A method for dividing a processing object, wherein the sharp end of the groove to be cut is located in a range of 30% to 80% of the thickness of the substrate layer from the upper surface of the substrate layer after polishing.

15. In paragraph 1, The step of dividing the above processing object is: A method for dividing a workpiece, comprising: a step of polishing the lower surface of the substrate layer at least to a position adjacent to the pointed end of the groove to be cut; 16. In paragraph 1, In all of the above one or more relative movements, the processing beam has a Gaussian intensity profile, A method for dividing a machining object, wherein the machining beam has a Gaussian intensity profile and includes a plurality of machining beams arranged in the machining direction.

17. In paragraph 16, A method for dividing a processing object in which the spot size of the plurality of processing beams is 20㎛ or less.

18. In paragraph 16, A method for dividing a processing object in which the spacing between the plurality of processing beams is 1 to 5 mm.

19. In paragraph 16, The above-mentioned cutting groove includes a first portion extending downward from the material layer, and a second portion having a shape that becomes narrower as the depth increases in a cross-section perpendicular to the processing direction and has a pointed end, which partially extends from the first portion into the inside of the substrate layer. A method for dividing a processing object in which the width of the first portion is greater than the width of the second portion.

20. In paragraph 19, A method for dividing a workpiece, wherein the depth of the groove to be cut is at least 2.5 times the width of the upper edge of the first portion.

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