Processing method and processing apparatus

Abstract

To achieve processing for forming a groove along a street for sectioning a plurality of devices provided on a semiconductor wafer by a laser of smaller energy.SOLUTION: In a first step, scanning is performed along a processing object region while irradiating the processing object region with a first laser for forming a spot whose length in the width direction of the processing object region on a street is shorter than the width of the processing object region. In the first step, a first laser is irradiated such that a plurality of scanning trajectories of a spot of the first laser are formed in a width direction of a processing target region. In a second step subsequent to the first step, scanning is performed along the processing target region while irradiating the processing target region with a second laser that forms a spot having a length in the width direction of the processing target region corresponding to the width of the processing target region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosed technique relates to a processing method and processing apparatus for forming grooves in streets that separate a plurality of devices provided on a semiconductor wafer. [Background technology]

[0002] The following techniques are known as techniques for forming grooves in streets that separate multiple devices provided on a semiconductor wafer. For example, Patent Document 1 describes a laser processing device equipped with an optical axis swinging means that swings the optical axis of a pulsed laser beam oscillated from a pulsed laser beam oscillator and guides the beam to a condenser.

[0003] Patent Document 2 describes a method characterized in that a laser scribe head creates a two-dimensional array of laser beam spots.

[0004] Patent Document 3 describes a laser processing device that includes a spot shaping unit that shapes the spot shape of a pulsed laser beam emitted by an oscillator so that it is long in the Y-axis direction and short in the X-axis direction, and a polygon mirror that disperses the spot shaped by the spot shaping unit in the X-axis direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-68149 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-223677 [Patent Document 3] Japanese Patent Publication No. 2022-107953 Summary of the Invention [Problem to be solved by the invention]

[0006] Low-k films used as insulating films in semiconductor devices have low mechanical strength and are generally Blade dicing carries the risk of film peeling. Therefore, before blade dicing, laser grooving is performed, in which a pulsed laser is used to remove the wiring layer, including the low-k film, along the streets that separate multiple devices on the semiconductor wafer. Laser grooving poses problems such as heat damage to the device and generation of debris.

[0007] To address the heat issue, it is conceivable to use an ultrashort pulse laser with a pulse width on the order of pico to femto. However, laser heads capable of outputting ultrashort pulse lasers are generally expensive, and introducing them requires significant costs.

[0008] Another possible solution is to scan a low-energy laser multiple times along the street. However, if a metal-containing structure is present on the street, the low-energy laser may not be able to remove the structure even by scanning multiple times.

[0009] The disclosed technology has been made in consideration of the above points, and aims to realize processing to form grooves along streets that separate multiple devices formed on a semiconductor wafer using a laser with lower energy. [Means for solving the problem]

[0010] The processing method according to the disclosed technique includes: forming a slot for dividing a plurality of devices provided on a semiconductor wafer; A processing method for forming grooves along a street. This processing method includes a first step of irradiating a processing target area with a first laser beam, the first laser beam forming a spot whose length in the width direction of the processing target area on the street is shorter than the width of the processing target area, while scanning the processing target area, and a second step, after the first step, of irradiating a processing target area with a second laser beam, the second laser beam forming a spot whose length in the width direction of the processing target area is a length corresponding to the width of the processing target area, while scanning the processing target area. In the first step, the first laser beam is irradiated so that multiple scanning trajectories of the spot of the first laser are aligned in the width direction of the processing target area.

[0011] In the first step, the process of irradiating the area to be processed with the first laser, which forms a single spot, and scanning along the area to be processed may be carried out multiple times while changing the irradiation position of the first laser in the width direction of the area to be processed.

[0012] The first laser may form a plurality of spots arranged at different positions in the width direction of the processing target area.

[0013] The first laser may be applied so that the direction in which the plurality of spots are arranged is perpendicular to the direction in which the processing target area extends. The first laser may be applied so that the direction in which the plurality of spots are arranged is inclined with respect to the direction in which the processing target area extends.

[0014] The first laser may form a plurality of spots arranged at different positions in a width direction of the processing target area and a plurality of spots arranged at different positions in a scanning direction of the first laser.

[0015] In the first step, projections and recesses may be formed in a film or structure present in the processing target area by irradiating the first laser, or cracks or voids may be formed in the film or structure.

[0016] In the first step, the film or structure present in the processing target area may be divided or fractured by irradiation with the first laser, or irregularities may be formed on the surface of the film or structure.

[0017] In the second step, a film or structure present in the processing target region may be removed by irradiating the second laser.

[0018] A processing apparatus according to the disclosed technology is a processing apparatus for forming grooves along streets that partition multiple devices on a semiconductor wafer. This processing apparatus includes: a first laser irradiation means that irradiates the processing target area with a first laser that forms a spot on the street whose length in the width direction of the processing target area is shorter than the width of the processing target area, while scanning the processing target area; and a second laser irradiation means that irradiates the processing target area with a second laser that forms a spot whose length in the width direction of the processing target area corresponds to the width of the processing target area, while scanning the processing target area. The first laser irradiation means irradiates the first laser so that multiple scanning trajectories of the first laser spot are aligned in the width direction of the processing target area. [Effects of the Invention]

[0019] According to the disclosed technology, it is possible to perform processing to form grooves along streets that separate multiple devices provided on a semiconductor wafer using a laser with lower energy. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 10 is a plan view showing an example of a processing mode in a first step according to an embodiment of the disclosed technique. [Figure 2] FIG. 10 is a plan view showing an example of a processing mode in a first step according to an embodiment of the disclosed technique. [Figure 3] FIG. 10 is a plan view showing an example of a processing mode in a first step according to an embodiment of the disclosed technique. [Figure 4A] 10 is a cross-sectional view showing an example of the state of a processing target region after completion of a first step according to an embodiment of the disclosed technique. FIG. [Figure 4B] 10 is a cross-sectional view showing an example of the state of a processing target region after completion of a first step according to an embodiment of the disclosed technique. FIG. [Figure 4C] 10 is a cross-sectional view showing an example of the state of a processing target region after completion of a first step according to an embodiment of the disclosed technique. FIG. [Figure 5] FIG. 2 is a diagram illustrating an example of the configuration of a first laser optical system used in a first step according to an embodiment of the disclosed technique. [Figure 6] 10 is a diagram showing another example of the configuration of the first laser optical system used in the first step according to the embodiment of the disclosed technique. FIG. [Figure 7] 10 is a diagram showing another example of the configuration of the first laser optical system used in the first step according to the embodiment of the disclosed technique. FIG. [Figure 8] FIG. 10 is a plan view showing an example of a processing mode in a second step according to an embodiment of the disclosed technique. [Figure 9] 10 is a cross-sectional view showing an example of the state of a processing target region after completion of a second step according to an embodiment of the disclosed technique. FIG. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of a second laser optical system used in a second step according to an embodiment of the disclosed technique. [Figure 11A] 10 is an image showing the state of a street when a groove is formed along the street by a processing method according to a comparative example. [Figure 11B] 10 is an image showing the state of a street when a groove is formed along the street by a processing method according to the disclosed technique. [Figure 12] FIG. 10 is a plan view showing an example of a processing mode in a first step according to another embodiment of the disclosed technique. [Figure 13] FIG. 10 is a plan view showing an example of a processing mode in a first step according to another embodiment of the disclosed technique. [Figure 14]FIG. 10 is a plan view showing an example of another aspect of the treatment in the first step according to another embodiment of the disclosed technique. [Figure 15] FIG. 10 is a plan view showing an example of another aspect of the treatment in the first step according to another embodiment of the disclosed technique. [Figure 16] FIG. 10 is a diagram showing an example of the configuration of a first laser optical system used in a first step according to another embodiment of the disclosed technique. [Figure 17] 10 is a diagram showing another example of the configuration of the first laser optical system used in the first step according to another embodiment of the disclosed technique. FIG. [Figure 18] 10 is a diagram showing another example of the configuration of the first laser optical system used in the first step according to another embodiment of the disclosed technique. FIG. [Figure 19] 10A to 10C are diagrams illustrating an example of a method for adjusting the rotation angle of a diffractive optical element according to an embodiment of the disclosed technique. [Figure 20] FIG. 10 is a plan view showing an example of a processing mode in a first step according to another embodiment of the disclosed technique. [Figure 21] FIG. 10 is a diagram showing an example of the configuration of a first laser optical system used in a first step according to another embodiment of the disclosed technique. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the disclosed technology will be described with reference to the drawings. In each drawing, substantially the same or equivalent components or parts are denoted by the same reference numerals.

[0022] A processing method according to an embodiment of the disclosed technology is a method for forming grooves in streets that separate a plurality of devices provided on a semiconductor wafer, and relates to laser grooving applied in the manufacturing process of semiconductor devices. Laser grooving is a processing method that exposes silicon, the base material of the semiconductor wafer, by forming grooves along the streets while removing films or structures present on the streets with a pulsed laser. Laser grooving is performed prior to blade dicing for cutting semiconductor chips from the semiconductor wafer. The film to be removed in laser grooving may be, for example, an insulating film such as a low-k film present on the streets. In laser grooving, The structure to be removed in this process may be, for example, a metal such as a TEG (Test Element Group) electrode present on the street. In laser grooving, a processing target area is set on the street. The processing target area is the area contained in the street and is the area to be processed by laser irradiation. The processing target area extends along the street. In the following, the direction in which the street extends (i.e., the direction in which the processing target area extends) is defined as the X direction, the width direction of the street (i.e., the width direction of the processing target area) is defined as the Y direction, and the depth direction of the semiconductor wafer is defined as the Z direction, and these directions will be clearly indicated in each figure.

[0023] [First embodiment] A processing method according to an embodiment of the disclosed technology includes a first step and a second step. FIG. 1 is a plan view showing an example of a processing mode in the first step. In the first step, a first laser is irradiated onto a processing target area 10 set on a street 2 and scanned along the processing target area 10. A length d1 of the first laser spot 11 in the width direction (Y direction) of the processing target area 10 is shorter than a width W of the processing target area 10. The shape of the first laser spot 11 is not particularly limited, but may be, for example, circular. Alternatively, as shown in FIGS. 2 and 3, the shape of the first laser spot 11 may be rectangular or elliptical with the longitudinal direction of the spot oriented in the extension direction (X direction) of the processing target area 10.

[0024] In the first step, the first laser is irradiated so that multiple scanning trajectories 12 of the spot 11 of the first laser are aligned in the width direction (Y direction) of the processing target area 10. For example, as shown in Fig. 1, the process of scanning the processing target area 10 along the processing target area 10 while irradiating the processing target area 10 with the first laser forming a single spot 11 may be performed multiple times while changing the irradiation position of the first laser in the width direction (Y direction) of the processing target area 10.

[0025] 4A, 4B, and 4C are cross-sectional views (YZ cross-sectional views) showing an example of the state of the processing target area 10 after the first step is completed. A semiconductor wafer to which the processing method according to this embodiment is applied has a substrate 100 made of a semiconductor such as silicon, and an insulating film 101 provided on the surface of the substrate 100. The insulating film 101 extends not only in the region where the semiconductor device is formed, but also in the processing target area 10. The insulating film 101 is, for example, SiO2, and may be a so-called low-k film. The insulating film 101 present in the processing target area 10 is, for example, SiO2, and may be a so-called low-k film. This is the target to be removed in the laser grooving according to the embodiment. Note that structures such as TEG electrodes may exist in the processing target region 10, and such structures are also the target to be removed.

[0026] 4A, in the first step, a first laser may be irradiated to form irregularities 102 on the surface of an insulating film 101 present in a processing target area 10. By irradiating the processing target area 10 with the first laser so that multiple scanning trajectories of a spot 11 of the first laser are aligned in the width direction (Y direction) of the processing target area 10, the irregularities 102 can be formed over a wide range in the width direction of the processing target area 10.

[0027] Also, as shown in FIG. 4B, in the first step, the object to be processed is irradiated with the first laser. Cracks 103 may be generated in the insulating film 101 present in the region 10. The cracks 103 extend from the surface of the insulating film 101 in the depth direction (Z direction) of the semiconductor wafer. By irradiating the region 10 to be processed with the first laser so that multiple scanning trajectories of the spot 11 of the first laser are aligned in the width direction (Y direction) of the region 10 to be processed, multiple cracks 103 aligned in the width direction of the region 10 to be processed can be generated.

[0028] 4C, in the first step, voids 104 may be formed in the insulating film 101 present in the processing target area 10 by irradiating with a first laser. The voids 104 extend from the surface of the insulating film 101 in the depth direction (Z direction) of the semiconductor wafer. By irradiating with the first laser so that multiple scanning trajectories of the spot 11 of the first laser are aligned in the width direction (Y direction) of the processing target area 10, multiple voids 104 aligned in the width direction of the processing target area 10 can be formed.

[0029] At the completion of the first step, one of the irregularities 102, cracks 103, and voids 104 may be formed in the insulating film 101 present in the processing target area 10, or two or more of the irregularities 102, cracks 103, and voids 104 may be present together. Furthermore, in the first step, the insulating film 101 present in the processing target area 10 may be divided or fractured by irradiation with the first laser. If a structure such as a TEG electrode is present in the processing target area 10, in the first step, irregularities may be formed on the surface of the structure, cracks may be generated in the structure, or voids may be formed in the structure by irradiation with the first laser. In the first step, the structure present in the processing target area 10 may be divided or fractured by irradiation with the first laser.

[0030] FIG. 5 is a diagram showing an example of the configuration of the first laser optical system 30 used in the first step. The first laser optical system 30 has a laser oscillator 31 and a lens 32. The semiconductor wafer 1 to be processed is held on a stage 50. The laser oscillator 31 outputs a first laser L1. The first laser L1 may be a UV pulse laser. The first laser L1 output from the laser oscillator 31 is irradiated onto the surface of the semiconductor wafer 1 via the lens 32. The focus of the lens 32 is adjusted to the surface of the semiconductor wafer 1, and a spot of the first laser L1 is formed on the surface of the semiconductor wafer 1. By moving the stage 50 in the X and Y directions, it is possible to move the irradiation position of the first laser L1 along the processing target region 10. In order to avoid damage to the device and the generation of debris due to heat, the energy per spot of the first laser L1 is set to 10 μJ or less. It is preferable that the output of the laser oscillator 31 be controlled in this manner.

[0031] 6 and 7 are diagrams showing other examples of the configuration of the first laser optical system 30 used in the first step. As shown in Fig. 6, the first laser optical system 30 may include a beam shaper 33 for shaping the spot of the first laser L1 into a desired shape. As shown in Fig. 7, the first laser optical system 30 may include a 4f optical system 34 for removing noise. The first laser optical system 30 may also include a beam expander (not shown) for adjusting the beam diameter to an appropriate size and an attenuator (not shown) for adjusting the laser output.

[0032] FIG. 8 is a plan view showing an example of the processing mode in the second step. The second step is carried out after the first step. In the second step, the second laser is scanned along the processing target area 10 while irradiating the processing target area 10 with the second laser. The length d2 of the second laser spot 21 in the width direction (Y direction) of the processing target area 10 is the same as or slightly shorter than the width W of the processing target area 10. It is preferable that the length d2 of the second laser spot 21 in the width direction (Y direction) of the processing target area 10 is 80% or more and less than 100% of the width W of the processing target area 10. The length d2 of the second laser spot 21 in the width direction (Y direction) of the processing target area 10 is shorter than the length d1 of the first laser spot 11 in the width direction (Y direction) of the processing target area 10. The shape of the spot 21 of the second laser may be rectangular, as exemplified in Fig. 8, or may be elliptical, oval, or circular.

[0033] FIG. 9 is a cross-sectional view (YZ cross-sectional view) showing an example of the state of the processing target area 10 after the second step is completed. In the second step, the insulating film 101 present in the processing target area 10 is removed by irradiation with the second laser. If a structure such as a TEG electrode is present in the processing target area 10, the structure present in the processing target area 10 is removed by irradiation with the second laser in the second step. As a result, a groove 110 is formed in the semiconductor wafer along the street 2, and the substrate 100 is exposed at the bottom of the groove 110. That is, in the second step, the insulating film 101 or structure present in the processing target area 10 is removed by laser ablation. Laser ablation is a phenomenon in which, when the irradiation intensity of laser light reaches a certain level or higher, electron, thermal, photochemical, and mechanical energy is exchanged on the surface of a solid. As a result, neutral atoms, molecules, positive and negative ions, clusters, electrons, and photons are emitted, and plasma with an electron temperature reaching several thousand degrees is generated, thereby removing the surface of a solid.

[0034] By performing the first step before performing the second step, it is possible to reduce the energy of the second laser irradiated in the second step. The reason for this is presumed to be as follows: As shown in Fig. 4A, in the first step, asperities 102 are formed on the surface of the insulating film 101 or structure present in the processing target area 10 by irradiating the first laser, thereby increasing the surface area of ​​the insulating film 101 or structure. This promotes energy absorption by the insulating film 101 or structure of the second laser irradiated in the second step, making it possible to remove the insulating film 101 or structure with a second laser having lower energy.

[0035] 4B, in the first step, the first laser irradiation generates cracks 103 in the insulating film 101 or structure present in the processing target area 10, thereby mechanically and thermally dividing the insulating film 101 or structure. This suppresses the diffusion and release of heat generated in the insulating film 101 or structure by the second laser irradiation in the second step, making it possible to remove the insulating film 101 or structure with the second laser having lower energy.

[0036] 4C , in the first step, voids 104 are formed in the insulating film 101 or structure present in the processing target area 10 by irradiating the first laser, thereby mechanically and thermally dividing the insulating film 101 or structure. This not only suppresses the diffusion and release of heat generated in the insulating film 101 or structure by irradiating the second laser in the second step, but also reduces the volume of the object to be removed, making it possible to remove the insulating film 101 or structure with the second laser having lower energy.

[0037] FIG. 10 is a diagram showing an example of the configuration of the second laser optical system 40 used in the second step. The second laser optical system 40 has a laser oscillator 41, a beam shaper 43, and a lens 42. The semiconductor wafer 1 to be processed is held on a stage 50. The laser oscillator 41 outputs a second laser L2. The second laser L2 may be a UV pulse laser. The second laser L2 output from the laser oscillator 41 is shaped by the beam shaper 43 into an elongated spot shape as shown in FIG. 8, and is irradiated onto the surface of the semiconductor wafer 1 via the lens 42. The focus of the lens 42 is adjusted to the surface of the semiconductor wafer 1, and a spot of the second laser L2 is formed on the surface of the semiconductor wafer 1. By moving the stage 50 in the X and Y directions, the irradiation position of the second laser L2 can be moved along the processing target area 10. In order to avoid damage to the device and generation of debris due to heat, it is preferable to control the output of the laser oscillator 41 so that the energy per spot of the second laser L2 is 10 μJ or less. stomach.

[0038] The laser oscillator 41 may be the same as the laser oscillator 31 constituting the first laser optical system 30, or may be a different one. When a laser oscillator is shared between the first and second steps, a means for switching the optical path of the laser light output from the laser oscillator is provided. Alternatively, a means for switching between inserting into and retracting from the optical path optical elements such as lenses and beam shapers used in each step may be provided. Furthermore, the second laser optical system 40 may include a beam expander (not shown) for adjusting the beam diameter to an appropriate size and an attenuator (not shown) for adjusting the laser output.

[0039] As described above, the processing method according to the embodiment of the disclosed technology includes a first step of irradiating the processing target area 10 with a first laser L1 that forms a spot 11 whose length in the width direction (Y direction) of the processing target area 10 is shorter than the width of the processing target area 10 while scanning the processing target area 10, and a second step, after the first step, of irradiating the processing target area 10 with a second laser L2 that forms a spot 21 whose length in the width direction (Y direction) of the processing target area 10 corresponds to the width of the processing target area 10 while scanning the processing target area 10. In the first step, the first laser L1 is irradiated so that multiple scanning trajectories 12 of the spot 11 of the first laser L1 are aligned in the width direction (Y direction) of the processing target area 10.

[0040] In the first step, the first laser L1, which forms a spot 11 whose length d1 in the width direction (Y direction) of the processing target area 10 is shorter than the width W of the processing target area 10, is irradiated onto the processing target area 10 while scanning along the processing target area 10, and the first laser L1 is irradiated so that multiple scanning trajectories of the spot 11 of the first laser L1 are aligned in the width direction (Y direction) of the processing target area 10. This forms at least one of irregularities 102, cracks 103, and voids 104 in the insulating film 101 or structure present in the processing target area 10. This promotes energy absorption in the insulating film 101 or structure of the second laser L2 irradiated in the second step. Alternatively, the diffusion and release of heat generated in the insulating film 101 or structure by the irradiation of the second laser L2 is suppressed. Therefore, the energy of the second laser L2 required to remove the insulating film 101 or structure can be reduced. In other words, according to the processing method according to the embodiment of the disclosed technology, it is possible to perform processing to form grooves along the streets that separate multiple devices provided on a semiconductor wafer using a laser with lower energy.

[0041] In laser grooving, damage to devices and generation of debris due to heat are problems. According to the processing method according to the embodiment of the disclosed technology, it is possible to address the heat problem without using an ultrashort pulse laser, which requires a large introduction cost. Furthermore, it is possible to appropriately remove insulating films or structures despite the low energy laser output.

[0042] FIG. 11A is an image showing the state of a street when a groove is formed along the street by a processing method according to a comparative example, and FIG. 11B is an image showing the state of a street when a groove is formed along the street by a processing method according to the disclosed technology. In the processing method according to the comparative example, the first step was not performed, and in the second step, a 10 μJ laser was scanned along the street twice. According to the processing method according to the comparative example, a portion of the TEG electrode, which is a structure present on the street, remained without being removed. On the other hand, in the processing method (Example) according to the disclosed technology, the first step was performed, and in the second step, an 8 μJ laser was scanned along the street once. According to the processing method according to the disclosed technology, even though the laser energy was smaller than that of the comparative example and only one scan was performed in the second step, the insulating film and structure present on the street were able to be removed without leaving any residue.

[0043] In the above explanation, a processing method including the first and second steps has been exemplified, but edge cutting processing may be performed before or after the first step to form two parallel grooves along the street at both ends of the street. For edge cutting processing, the technology described in JP 2021-192922 A can be applied.

[0044] [Second embodiment] 12 is a plan view showing an example of a processing mode in the first step according to the second embodiment of the disclosed technology. In the second embodiment, as in the first embodiment described above, the first laser is irradiated in the first step so that multiple scanning trajectories 12 of the first laser spot 11 are aligned in the width direction (Y direction) of the processing target area 10.

[0045] In the second embodiment, as shown in FIG. 12, a first laser beam, which forms multiple spots 11 arranged at different positions in the width direction (Y direction) of the processing target area 10, is irradiated onto the processing target area 10 and scanned along the processing target area 10. The direction in which the multiple spots 11 are arranged may be perpendicular to the extension direction (X direction) of the processing target area 10 (FIG. 12) or inclined (FIG. 13). Even with this configuration, it is possible to form at least one of irregularities, cracks, and voids in the insulating film or structure present in the processing target area 10 at the completion of the first step. The shape of the first laser beam spot 11 is not particularly limited, and may be, for example, circular. Alternatively, as shown in FIGS. 14 and 15, the shape of the first laser beam spot 11 may be rectangular or elliptical with the longitudinal direction of the spot oriented in the extension direction (X direction) of the processing target area 10.

[0046] 16 is a diagram showing an example of the configuration of a first laser optical system 30A used in the first step according to the second embodiment. The first laser optical system 30A has a laser oscillator 31, a diffractive optical element (DOE) 35, and a lens 32. That is, the first laser optical system 30A has a configuration in which a diffractive optical element 35 is added to the laser optical system 30 according to the first embodiment illustrated in FIG.

[0047] The first laser beam L1 output from the laser oscillator 31 is optically branched by passing through the diffractive optical element 35. As a result, multiple spots 11 arranged in a line are formed on the surface of the semiconductor wafer 1, as shown in FIGS. 12 and 13. The diffractive optical element 35 is rotatable around the optical axis of the first laser beam L1. The direction in which the multiple spots 11 of the first laser beam L1 are arranged can be changed by changing the rotation angle of the diffractive optical element 35. The rotation angle of the diffractive optical element 35 is adjusted so that the multiple spots 11 are arranged at different positions in the width direction (Y direction) of the processing target area 10. The irradiation position of the first laser beam can be moved along the processing target area 10 by moving the stage 50 in the X and Y directions. To avoid thermal damage to the device and the generation of debris, it is preferable to control the output of the laser oscillator 31 so that the energy per spot of the first laser beam L1 is 10 μJ or less.

[0048] 17 and 18 are diagrams showing other examples of the configuration of the first laser optical system 30A. As shown in Fig. 17, the first laser optical system 30A may include a beam shaper 33 for shaping the spot of the first laser L1 into a desired shape. As shown in Fig. 18, the first laser optical system 30A may include a 4f optical system 34 for removing noise. The first laser optical system 30A may also include a beam expander (not shown) for adjusting the beam diameter to an appropriate size and an attenuator (not shown) for adjusting the laser output.

[0049] 19 is a diagram showing an example of a method for adjusting the rotation angle of the diffractive optical element 35. Diffracted light The rotation angle of the optical element 35 coincides with the tilt angle θ of the direction in which the multiple spots 11 are arranged relative to the extension direction (X direction) of the processing target area 10. The tilt angle θ is expressed by the following equation (1). In equation (1), A1 is the length in the width direction (Y direction) of the processing target area 10 by the first laser. A1 may be the same as or slightly smaller than the width W of the processing target area 10. Also, in equation (1), A2 is the length from one end to the other end of the multiple spots 11 of the first laser. θ=Arcsin(A1 / A2) (1)

[0050] As described above, according to the processing method of the second embodiment of the disclosed technology, the first step includes scanning the processing target area 10 while irradiating the processing target area 10 with the first laser L1, which forms multiple spots 11 arranged at different positions in the width direction of the processing target area 10. According to the processing method of the second embodiment, similar to the processing method of the first embodiment, it is possible to achieve processing to form grooves along the streets 2 using a laser with lower energy. Furthermore, because the first laser L1 forms multiple spots 11 arranged at different positions in the width direction of the processing target area 10, the number of scans required to align multiple scanning trajectories of the spots in the width direction of the processing target area 10 can be reduced compared to when the first laser L1 forms a single spot. This allows the processing time of the first step to be shortened compared to when the first laser L1 forms a single spot.

[0051] Although the above description has been given of an example in which the multiple spots 11 are spaced apart from one another, the multiple spots 11 may be connected in a line. That is, each spot 11 may partially overlap with an adjacent spot 11.

[0052] [Third embodiment] 20 is a plan view showing an example of a processing mode in the first step according to the third embodiment of the disclosed technology. In the third embodiment, as in the first embodiment described above, the first laser is irradiated so that multiple scanning trajectories 12 of the first laser spot 11 are aligned in the width direction (Y direction) of the processing target area 10.

[0053] 20 , a first laser that forms multiple spots 11 arranged at different positions in the width direction (Y direction) of the processing target area 10 and multiple spots 11 arranged at different positions in the scanning direction (X direction) of the first laser is irradiated onto the processing target area 10 and scanned along the processing target area 10. Even with this configuration, it is possible to form at least one of irregularities, cracks, and voids in the insulating film or structure present in the processing target area 10 at the completion of the first step. The shape of the first laser spot 11 is not particularly limited, and may be, for example, circular. Alternatively, the shape of the first laser spot 11 may be rectangular or elliptical with the longitudinal direction of the spot oriented in the extension direction (X direction) of the processing target area 10.

[0054] 21 is a diagram showing an example of the configuration of a first laser optical system 30B used in the first step according to the third embodiment. The first laser optical system 30B according to the third embodiment has a laser oscillator 31, diffractive optical elements 35A and 35B, and a lens 32. That is, the first laser optical system 30B according to the third embodiment has a configuration in which two diffractive optical elements 35A and 35B are added to the laser optical system 30 according to the first embodiment shown in FIG.

[0055] The diffractive optical element 35A splits the first laser L1 output from the laser oscillator 31 in the width direction (Y direction) of the processing target area 10. The diffractive optical element 35B splits the first laser L1 split by the diffractive optical element 35A in the extension direction (X direction) of the processing target area 10. The diffractive optical elements 35A and 35B are each rotatable about the optical axis of the first laser L1. The direction in which the first laser L1 spots 11 are arranged can be changed by changing the rotation angle of the diffractive optical elements 35A and 35B. The irradiation position of the first laser L1 can be moved along the processing target region 10 by moving the stage 50 in the X and Y directions. To avoid damage to the device and the generation of debris due to heat, it is preferable to control the output of the laser oscillator 31 so that the energy per spot of the first laser L1 is 10 μJ or less.

[0056] The first laser optical system 30B may include a beam shaper for shaping the spot of the first laser L1 into a desired shape, following the examples of Figures 17 and 18. The first laser optical system 30B may also include a 4f optical system for removing noise. The first laser optical system 30B may also include a beam expander (not shown) for adjusting the beam diameter to an appropriate size and an attenuator (not shown) for adjusting the laser output.

[0057] As described above, according to the processing method of the third embodiment of the disclosed technology, the first step includes scanning the processing target area 10 while irradiating the processing target area 10 with the first laser L1, which forms multiple spots 11 arranged at different positions in the width direction of the processing target area 10 and multiple spots 11 arranged at different positions in the scanning direction of the first laser. According to the processing method of the third embodiment, as with the processing method of the first embodiment, it is possible to achieve processing to form grooves along the streets 2 using a laser with lower energy. Furthermore, as with the processing method of the second embodiment, it is possible to reduce the number of scans required to align multiple scanning trajectories of the spots 11 in the width direction of the processing target area 10, thereby shortening the processing time of the first step. [Explanation of symbols]

[0058] 1. Semiconductor wafer 2 Street 10 Processing area 11 Spots 12 Scanning trajectory 21 Spots 30, 30A, 30B laser optics 31 Laser oscillator 32 Lens 33 Beam Shaper 34 4f optical system 35, 35A, 35B Diffractive optical elements 40 Laser Optics 41 Laser oscillator 42 Lens 43 Beam Shaper 50 stages 100 boards 101 insulating film 102 Unevenness 103 Crack 104 void

Claims

1. 1. A processing method for forming grooves along streets that separate a plurality of devices provided on a semiconductor wafer, comprising: a first step of scanning the processing target area along the processing target area while irradiating the processing target area with a first laser that forms a spot whose length in the width direction of the processing target area on the street is shorter than the width of the processing target area; a second step of scanning the processing target area while irradiating the processing target area with a second laser that forms a spot whose length in the width direction of the processing target area corresponds to the width of the processing target area after the first step; Including, In the first step, the first laser is irradiated so that a plurality of scanning trajectories of the spot of the first laser are aligned in the width direction of the processing target area. Processing method.

2. In the first step, the process of scanning the target area while irradiating the target area with the first laser that forms a single spot is carried out multiple times while changing the irradiation position of the first laser in the width direction of the target area. The processing method according to claim 1.

3. The first laser forms a plurality of spots arranged at different positions in the width direction of the processing target area. The processing method according to claim 1.

4. The first laser is irradiated so that the direction in which the plurality of spots are arranged is perpendicular to the direction in which the processing target area extends. The processing method according to claim 3.

5. The first laser is irradiated so that the direction in which the plurality of spots are arranged is inclined with respect to the direction in which the processing target area extends. The processing method according to claim 3.

6. The first laser forms a plurality of spots arranged at different positions in the width direction of the processing target area and a plurality of spots arranged at different positions in the scanning direction of the first laser. The processing method according to claim 1.

7. In the first step, the first laser is irradiated to form irregularities in a film or structure present in the processing target area, or to form cracks or voids in the film or structure. The processing method according to claim 1.

8. In the first step, the film or structure present in the processing target area is divided or fractured by the irradiation of the first laser, or irregularities are formed on the surface of the film or the structure. The processing method according to claim 1.

9. In the second step, a film or structure present in the processing target area is removed by irradiating the second laser. The processing method according to claim 1.

10. A processing apparatus for forming grooves along streets that separate a plurality of devices provided on a semiconductor wafer, comprising: a first laser irradiation means for irradiating the area to be processed with a first laser that forms a spot whose length in the width direction of the area to be processed on the street is shorter than the width of the area to be processed, while scanning the area to be processed along the area to be processed; a second laser irradiation means for irradiating the processing target area with a second laser that forms a spot whose length in the width direction of the processing target area corresponds to the width of the processing target area while scanning the processing target area; Including, The first laser irradiation means irradiates the first laser so that a plurality of scanning trajectories of the spot of the first laser are aligned in the width direction of the processing target area. Processing equipment.

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