WO2017126506A1 - Procédé de découpe d'un objet à traiter - Google Patents

Procédé de découpe d'un objet à traiter Download PDF

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Publication number
WO2017126506A1
WO2017126506A1 PCT/JP2017/001422 JP2017001422W WO2017126506A1 WO 2017126506 A1 WO2017126506 A1 WO 2017126506A1 JP 2017001422 W JP2017001422 W JP 2017001422W WO 2017126506 A1 WO2017126506 A1 WO 2017126506A1
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WO
WIPO (PCT)
Prior art keywords
workpiece
laser light
laser
light
cutting
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PCT/JP2017/001422
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English (en)
Japanese (ja)
Inventor
惇治 奥間
陽 杉本
Original Assignee
浜松ホトニクス株式会社
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Priority to JP2017562821A priority Critical patent/JP6752232B2/ja
Publication of WO2017126506A1 publication Critical patent/WO2017126506A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/50—Working by transmitting the laser beam through or within the workpiece
    • B23K26/53—Working by transmitting the laser beam through or within the workpiece for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks

Definitions

  • One aspect of the present invention relates to a workpiece cutting method.
  • Patent Document 1 describes a semiconductor chip manufacturing method.
  • a semiconductor wafer formed by laminating an n-type gallium nitride semiconductor layer (n-type layer) and a p-type gallium nitride semiconductor layer (p-type layer) on a sapphire substrate is divided into a plurality of semiconductor chips.
  • an element isolation groove is formed with a desired chip shape.
  • the element isolation trench is formed by etching the p-type layer.
  • a modified region is formed inside the sapphire substrate.
  • the modified region is formed by irradiating a laser beam with the focusing point inside the sapphire substrate.
  • the modified region is used for dividing the substrate (wafer). Thereafter, the substrate (wafer) is divided into chips using a braking device.
  • a light shielding region that shields laser light may be provided on the surface of a workpiece such as the substrate (wafer).
  • the surface is used as a laser light incident surface, and the laser light is irradiated onto the workpiece while moving the condensing point of the laser light so as to pass through the light shielding region as seen from the direction intersecting the incident surface.
  • the laser light is irradiated onto the workpiece while moving the condensing point of the laser light so as to pass through the light shielding region as seen from the direction intersecting the incident surface.
  • An object of one aspect of the present invention is to provide a processing object cutting method capable of suppressing deterioration of a cut surface.
  • a processing object cutting method is a processing object cutting method for cutting a processing object having a main surface including a light shielding region that shields laser light along a cutting scheduled line.
  • the first step of making the laser beam incident on a condensing lens for condensing the laser beam on the workpiece, and the laser beam while condensing the laser beam inside the workpiece by the condenser lens And a second step of forming a modified region inside the workpiece along the planned cutting line by relatively moving the condensing point along the planned cutting line.
  • the laser beam is incident on the condensing lens in a state where the intensity profile of the laser beam is annulus.
  • step 2 The main surface with a plane of incidence of the laser light along the line to cut so as to pass through the light shielding region when viewed from a direction intersecting the principal surface relatively moving the converging point.
  • the workpiece has a main surface including a light shielding region that shields laser light.
  • the main surface is used as the laser light incident surface, and the condensing point is relatively moved along the planned cutting line so as to pass through the light shielding region.
  • the present inventors collect a laser beam having an annular intensity profile and irradiate the object to be processed, so that there is a portion where the modified region is missing at a position corresponding to the light shielding region. It was found that it is possible to suppress the occurrence.
  • laser light having an annular intensity profile is incident on the condenser lens. Therefore, according to this method, generation
  • the workpiece has a semiconductor layer for a semiconductor laser containing gallium nitride, the semiconductor layer includes a main surface, and the light shielding region is cut.
  • the stripe-shaped high-density defect region provided in the semiconductor layer so as to extend in a direction crossing the planned line, and the planned cutting line may be set along the cleavage plane of the semiconductor layer.
  • the modified region is formed along the planned cutting line set along the cleavage plane of the semiconductor layer for the semiconductor laser so as not to cause a missing portion as described above. Is possible. For this reason, it is possible to suppress the degradation of the cut surface (cleavage surface) and realize the mirror surface of the cut surface.
  • the intensity profile in the first step, may be formed in an annular shape by a spatial light modulator presenting a predetermined modulation pattern.
  • the annular shape of the intensity profile of the laser light can be dynamically changed by controlling a predetermined modulation pattern of the spatial light modulator. Therefore, it is possible to form an appropriate modified region according to the material of the workpiece, the required cutting accuracy, and the like.
  • FIG. 3 is a cross-sectional view taken along the line II-II of the workpiece of FIG. It is a top view of the processing target after laser processing.
  • FIG. 5 is a cross-sectional view taken along the line VV of the workpiece in FIG. 4.
  • FIG. 5 is a cross-sectional view taken along line VI-VI of the workpiece in FIG. 4. It is a perspective view which shows the chip
  • FIG. 1 It is a figure which shows the process target object of the process target cutting method which concerns on this embodiment. It is a figure which shows the structure of the optical system shown by FIG. It is a figure which shows the intensity profile of a laser beam. It is sectional drawing which shows the main processes of the workpiece cutting method which concerns on this embodiment. It is a figure which shows the cut surface of a workpiece. It is a figure for demonstrating the relationship between the offset amount of a beam center and a light shielding area
  • the processing object cutting method irradiates the processing object with laser light along the planned cutting line, thereby improving the cutting starting point at least inside the processing target along the planned cutting line. Form a region. First, the formation of the modified region will be described with reference to FIGS.
  • a laser processing apparatus 100 includes a laser light source 101 that oscillates a laser beam L, a dichroic mirror 103 that is arranged to change the direction of the optical axis (optical path) of the laser beam L by 90 °, and , And a condensing lens 105 for condensing the laser light L on the workpiece 1.
  • the laser processing apparatus 100 includes a support base 107 for supporting the workpiece 1 irradiated with the laser light L condensed by the condenser lens 105, a stage 111 for moving the support base 107, A laser light source control unit 102 that controls the laser light source 101 in order to adjust the output, pulse width, pulse waveform, and the like of the laser light L, and a stage control unit 115 that controls the movement of the stage 111 are provided.
  • the laser light L emitted from the laser light source 101 is changed in the direction of its optical axis by 90 ° by the dichroic mirror 103, and is placed inside the processing object 1 placed on the support base 107.
  • the light is collected by the condenser lens 105.
  • the stage 111 is moved, and the workpiece 1 is moved relative to the laser beam L along the planned cutting line 5. Thereby, a modified region along the planned cutting line 5 is formed on the workpiece 1.
  • the stage 111 is moved in order to move the laser light L relatively, but the condenser lens 105 may be moved, or both of them may be moved.
  • the laser light L may be incident on the condenser lens 105 via the optical system 113.
  • a plate-like member for example, a substrate, a wafer, or the like
  • a scheduled cutting line 5 is set on the workpiece 1.
  • the planned cutting line 5 is a virtual line extending linearly.
  • the laser beam L is cut in a state where the condensing point (condensing position) P is aligned with the inside of the workpiece 1 as shown in FIG. 3. It moves relatively along the planned line 5 (that is, in the direction of arrow A in FIG. 2).
  • the modified region 7 is formed on the workpiece 1 along the planned cutting line 5.
  • the modified region 7 formed along the planned cutting line 5 becomes the cutting start region 8.
  • the condensing point P is a portion where the laser light L is condensed.
  • the planned cutting line 5 is not limited to a straight line, but may be a curved line, a three-dimensional shape in which these lines are combined, or a coordinate designated.
  • the planned cutting line 5 is not limited to a virtual line but may be a line actually drawn on the surface 3 of the workpiece 1.
  • the modified region 7 may be formed continuously or intermittently.
  • the modified region 7 may be in the form of a line or a dot. In short, the modified region 7 only needs to be formed at least inside the workpiece 1.
  • a crack may be formed starting from the modified region 7, and the crack and the modified region 7 may be exposed on the outer surface (front surface 3, back surface, or outer peripheral surface) of the workpiece 1. .
  • the laser light incident surface when forming the modified region 7 is not limited to the front surface 3 of the workpiece 1 and may be the back surface of the workpiece 1.
  • the modified region 7 when the modified region 7 is formed inside the workpiece 1, the laser light L passes through the workpiece 1 and is near the condensing point P located inside the workpiece 1. Especially absorbed. Thereby, the modified region 7 is formed in the workpiece 1 (that is, internal absorption laser processing). In this case, since the laser beam L is hardly absorbed by the surface 3 of the workpiece 1, the surface 3 of the workpiece 1 is not melted. On the other hand, when the modified region 7 is formed on the surface 3 of the workpiece 1, the laser light L is absorbed particularly near the condensing point P located on the surface 3 and melted and removed from the surface 3. Then, removal portions such as holes and grooves are formed (surface absorption laser processing).
  • the modified region 7 is a region where the density, refractive index, mechanical strength and other physical characteristics are different from the surroundings.
  • Examples of the modified region 7 include a melt treatment region (meaning at least one of a region once solidified after melting, a region in a molten state, and a region in a state of being resolidified from melting), a crack region, and the like.
  • a melt treatment region meaning at least one of a region once solidified after melting, a region in a molten state, and a region in a state of being resolidified from melting
  • a crack region and the like.
  • there are a dielectric breakdown region, a refractive index change region, etc. there is a region where these are mixed.
  • the modified region 7 includes a region in which the density of the modified region 7 is changed in comparison with the density of the non-modified region in the material of the workpiece 1 and a region in which lattice defects are formed (these are Collectively called high dislocation density region).
  • the area where the density of the melt processing area, the refractive index changing area, the density of the modified area 7 is changed as compared with the density of the non-modified area, and the area where lattice defects are formed are further included in the interior of these areas or the modified areas.
  • cracks (cracks, microcracks) are included in the interface between the region 7 and the non-modified region.
  • the included crack may be formed over the entire surface of the modified region 7, or may be formed in only a part or a plurality of parts.
  • the workpiece 1 includes a substrate made of a crystal material having a crystal structure.
  • the workpiece 1 includes a substrate formed of at least one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO 3 , and sapphire (Al 2 O 3 ).
  • the workpiece 1 includes, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO 3 substrate, or a sapphire substrate.
  • the crystal material may be either an anisotropic crystal or an isotropic crystal.
  • the modified region 7 can be formed by forming a plurality of modified spots (processing marks) along the planned cutting line 5.
  • the modified region 7 is formed by collecting a plurality of modified spots.
  • the modified spot is a modified portion formed by one pulse shot of pulsed laser light (that is, one pulse of laser irradiation: laser shot).
  • the modified spot include a crack spot, a melting treatment spot, a refractive index change spot, or a mixture of at least one of these.
  • the size and length of cracks to be generated are appropriately determined in consideration of the required cutting accuracy, required flatness of the cut surface, thickness, type, crystal orientation, etc. of the workpiece 1. Can be controlled.
  • FIG. 7 is a perspective view showing a chip manufactured using the workpiece cutting method according to the present embodiment.
  • the chip 10 is a semiconductor laser containing gallium nitride, for example.
  • the chip 10 includes a cut surface (for example, an m-plane in a gallium nitride crystal) 10a that is a cleavage plane, and another cut surface (for example, an a-plane in a gallium nitride crystal) 10b that intersects the cut surface 10a.
  • the chip 10 includes a substrate 11, a semiconductor layer 12 formed on the substrate 11, and an electrode 13 formed on the substrate 11 and the semiconductor layer 12.
  • the substrate 11 is a semiconductor substrate containing, for example, gallium nitride.
  • the substrate 11 is a GaN substrate, for example.
  • the semiconductor layer 12 is a semiconductor stacked portion formed by, for example, epitaxial growth.
  • the semiconductor layer 12 includes, for example, gallium nitride.
  • the semiconductor layer 12 includes a light emitting layer (active layer) 14 for a semiconductor laser, for example.
  • the light emitting layer 14 is embedded in the semiconductor layer 12.
  • the end surface 14s of the light emitting layer 14 is included in the cut surface 10a.
  • the end face 14s is a mirror surface that forms a laser resonator.
  • the electrode 13 is used for applying a voltage to the semiconductor layer 12.
  • the chip 10 includes a pair of stripe cores 15.
  • the stripe core 15 is provided in the semiconductor layer 12 so as to extend in a direction crossing the cut surface 10 a of the chip 10.
  • the stripe core 15 includes, for example, gallium nitride.
  • the stripe core 15 is a high density defect region.
  • the stripe core 15 shields the laser light L by, for example, scattering.
  • FIGS. 8 and 9 are diagrams showing a processing object of the processing object cutting method according to the present embodiment.
  • FIG. 8 is a plan view
  • FIG. 9A is a partially enlarged view of FIG.
  • FIG. 9B is a cross-sectional view taken along the line IX-IX in FIG.
  • the processing object cutting method according to the present embodiment first, the processing object 1 is prepared as shown in FIGS.
  • the workpiece 1 has a plurality of chip portions 20 for the chips 10.
  • the tip portion 20 has a direction parallel to the orientation flat 6 of the workpiece 1 (hereinafter sometimes referred to as “first direction”) and a direction orthogonal to the orientation flat 6 (hereinafter referred to as “second direction”). Are arranged in two dimensions.
  • the workpiece 1 has a substrate 21 for the substrate 11 provided over a plurality of chip portions 20. Further, the workpiece 1 has a semiconductor layer 22 for the semiconductor layer 12 provided over the plurality of chip portions 20. As described above, the semiconductor layer 22 is a semiconductor layer for a semiconductor laser containing, for example, gallium nitride. The semiconductor layer 22 is provided on the substrate 21. The semiconductor layer 22 includes a main surface 22 s that is a surface opposite to the substrate 21.
  • the workpiece 1 is set with a plurality of scheduled cutting lines 5a along the first direction and a plurality of scheduled cutting lines 5b along the second direction.
  • the planned cutting line 5a and the planned cutting line 5b cross each other (for example, orthogonal).
  • the chip 10 is obtained by cutting the workpiece 1 along the planned cutting line 5a and the planned cutting line 5b and cutting out the chip part 20. That is, a single chip portion 20 is defined by a region surrounded by a pair of cutting planned lines 5a adjacent to each other and a pair of cutting planned lines 5b adjacent to each other.
  • the cutting lines 5a are set along the cleavage planes of the substrate 21 and the semiconductor layer 22 (for example, the m-plane of gallium nitride crystal). Therefore, a pair of cutting lines 5a adjacent to each other defines the length of the chip portion 20 in the second direction (the resonator length of the semiconductor laser).
  • the planned cutting line 5b is set, for example, along the a-plane of the gallium nitride crystal. A pair of cutting planned lines 5b adjacent to each other defines the length of the chip portion 20 in the first direction.
  • the semiconductor layer 22 is provided with a plurality of stripe cores 15 extending along the second direction.
  • the chip portions 20 adjacent to each other in the first direction are partitioned by the stripe core 15.
  • the stripe core 15 extends along a direction intersecting (for example, orthogonal to) the cleavage plane (for example, m-plane of gallium nitride crystal) of the substrate 21 and the semiconductor layer 22.
  • the planned cutting line 5 b is set in the stripe core 15 along the stripe core 15.
  • the planned cutting line 5 a is set across a plurality of stripe cores 15 so as to intersect (for example, orthogonally) the stripe cores 15.
  • the stripe core 15 constitutes a part of the main surface 22 s of the semiconductor layer 22.
  • a region corresponding to the stripe core 15 in the main surface 22s is a light shielding region SA that shields the laser light L. Therefore, the light shielding area SA is a stripe-shaped high-density defect area provided in the semiconductor layer 22 so as to extend in a direction intersecting (for example, orthogonal to) the planned cutting line 5a.
  • the light shielding area SA overlaps a part of the planned cutting line 5a when viewed from the direction intersecting the main surface 22s. Further, the planned cutting line 5b is located in the light shielding area SA.
  • Each chip unit 20 includes an electrode 13 and a light emitting layer 14.
  • the electrode 13 is provided on the main surface 22s.
  • the light emitting layer 14 is provided (embedded) in the semiconductor layer 22 between the stripe cores 15 adjacent to each other.
  • the modified region 7 is formed by irradiating the workpiece 1 with the laser beam L. More specifically, first, as shown in FIGS. 1 and 10, the workpiece 1 is placed on the support base 107 so that the main surface 22 s (surface 3) is positioned on the condenser lens 105 side.
  • the condensing lens 105 is an objective lens arranged closest to the main surface 22 s among the lenses of the laser processing apparatus 100. Therefore, no optical element such as another lens is interposed between the condenser lens 105 and the main surface 22s.
  • the laser light L is incident on the condenser lens 105 for condensing the laser light L on the workpiece 1 (first step).
  • the laser light L is incident on the condenser lens 105 in a state where the intensity profile of the laser light L is annular.
  • the intensity profile here is an intensity distribution of the laser light L in a plane orthogonal to the optical axis Ax of the laser light L.
  • the optical system 113 is used to make the intensity profile of the laser light L when entering the condenser lens 105 into an annular shape.
  • the optical system 113 is provided between the laser light source 101 (here, the dichroic mirror 103) and the condenser lens 105 on the optical path of the laser light L.
  • the optical system 113 has a function for making the intensity profile of the laser light L into an annular shape.
  • the optical system 113 includes a pair of mirrors 121 and 123 and a spatial light modulator 122.
  • the mirror 121 deflects the laser light L from the laser light source 101 (dichroic mirror 103) toward the modulation surface 122s of the spatial light modulator 122.
  • the mirror 123 deflects the laser light L from the modulation surface 122 s of the spatial light modulator 122 toward the condenser lens 105.
  • the spatial light modulator 122 is, for example, an LCOS-SLM (Liquid Crystal On Silicon Spatial Light Modulator).
  • the spatial light modulator 122 has a modulation surface 122s including a liquid crystal layer and the like.
  • the spatial light modulator 122 presents a predetermined modulation pattern on the modulation surface 122s.
  • the spatial light modulator 122 modulates the light incident on the modulation surface 122s, changes the intensity profile, and emits the light. Therefore, in the first step, the intensity profile of the laser beam L is made annular by the spatial light modulator 122 presenting a predetermined modulation pattern.
  • FIG. 11 is a diagram showing the intensity profile of the laser beam.
  • FIG. 11A shows an intensity profile Pb of normal laser light L in a state where it is not modulated.
  • FIG. 11B shows an intensity profile Pa of the laser light L that is modulated using the spatial light modulator 122.
  • the optical system 113 uses a spatial light modulator 122 to convert a Gaussian beam having a solid circular intensity profile into a beam having an annular intensity profile. Here, a central circular region having a relatively high strength is cut.
  • it is set as the solid circle shape in the condensing point P.
  • the minimum inner diameter can be 1.50 mm and the maximum inner diameter can be 2.40 mm.
  • the condensing point 105 of the laser light L is focused on the cutting line 5a while condensing the laser light L inside the workpiece 1 by the condensing lens 105.
  • the modified region 7 is formed in the workpiece 1 along the planned cutting line 5a (second step). More specifically, in the second step, first, the surface of the workpiece 1 (the main surface 22s of the semiconductor layer 22) is the incident surface of the laser light L, and the condensing point P of the laser light L is the substrate. 21 is in a state matched to the inside. That is, the laser light L is condensed inside the substrate 21 through the semiconductor layer 22.
  • a plurality of modified spots 7 s are formed inside the substrate 21.
  • the modified region 7 is formed as a set of modified spots 7s.
  • the modified spot 7s is also formed in a portion (a portion corresponding to the light shielding region SA) located immediately below the light shielding region SA when viewed from the direction intersecting the main surface 22s. Therefore, here, the modified region 7 is not lost (interrupted) in the portion corresponding to the light shielding region SA.
  • the intensity profile of the laser beam L is maintained in an annular shape even when entering the main surface 22s.
  • this second step by adjusting the irradiation condition of the laser beam L, not only the inside of the substrate 21 but also the surface of the substrate 21 opposite to the semiconductor layer 22 (the back surface of the workpiece 1), for example. It is possible to cause cracks to reach. Further, the cracks extending from the adjacent modified spots 7s can be connected to each other.
  • the modified region 7 along all the planned cutting lines 5a is formed inside the workpiece 1 by sequentially performing this second step on all the planned cutting lines 5a.
  • the planned cutting line 5 a is set along the cleavage planes of the substrate 21 and the semiconductor layer 22. Therefore, in the second step, the modified region 7 is formed along the cleavage planes of the substrate 21 and the semiconductor layer 22.
  • the workpiece 1 can be cut along the planned cutting line 5a by cleaving from the modified region 7 as a starting point. Cutting of the workpiece 1 along the planned cutting line 5a can be performed by applying a force to the workpiece 1 in the direction of opening a crack extending from the modified region 7.
  • a plurality of bar-shaped processed objects including the plurality of chips 10 (chip portions 20) arranged along the scheduled cutting line 5a are obtained.
  • the substrate 11 is formed from the substrate 21 and the semiconductor layer 12 is formed from the semiconductor layer 22, and each chip 10 is obtained. It is done.
  • the planned cutting line 5b is located in the light shielding area SA throughout. Therefore, the cutting along the planned cutting line 5b is not a method of forming the modified region 7 inside the substrate 21 by the incidence of the laser light L from the main surface 22s, but a method such as laser ablation can be used. .
  • the laser light L is incident on the condenser lens 105 in the first step. Thereafter, in the second step, the laser beam L is condensed inside the workpiece 1 by the condensing lens 105, and the condensing point P is moved relative to the cutting target line 5a, so that the cutting is scheduled. A modified region 7 is formed inside the workpiece 1 along the line 5a.
  • the workpiece 1 has a main surface 22s including a light shielding area SA that shields the laser light L.
  • the main surface 22s is used as the incident surface of the laser light L, and the condensing point P is relatively moved along the planned cutting line 5a so as to pass through the light shielding area SA.
  • the missing part (disrupted) of the modified area 7 (Part) M may occur at the position corresponding to the light shielding area SA inside the workpiece 1.
  • the cut surface 10a may meander, and a step G may occur in the cut surface 10a.
  • the conventional method here means that in the first step, the intensity profile of the laser light L is not circular as shown in FIG. 14A, but is circular as shown in FIG. In this state, the laser beam L is made incident on the condenser lens 105 in the state where the intensity profile is maintained.
  • the present inventors collect the laser beam L having an annular intensity profile and irradiate the workpiece 1 with the laser beam L in the position corresponding to the light shielding region SA. It has been found that the occurrence of the missing portion M can be suppressed.
  • the laser beam L having an annular intensity profile is incident on the condenser lens 105 in the first step. Therefore, according to this processing object cutting method, as shown in FIG. 13A, the occurrence of the missing portion M of the modified region 7 at the position corresponding to the light shielding region SA is suppressed. As a result, it is possible to suppress degradation of the cut surface 10a such as a step G formed on the cut surface 10a.
  • the laser light L having an annular intensity profile and the laser light Ln having a normal (conventional) intensity profile having a solid circular shape As shown in FIG. 14 (c), the laser light L having an annular intensity profile and the laser light Ln having a normal (conventional) intensity profile having a solid circular shape, Depending on the positional relationship, the transmittance with respect to the workpiece 1 is different. This point will be described in more detail.
  • the offset amount between the beam centers of the laser beams L and Ln and the center of the light shielding area SA is Lo.
  • the offset amount Lo becomes 0 when the beam centers of the laser beams L and Ln coincide with the center of the light shielding area SA.
  • the offset Lo is displaced from the negative side to the positive side beyond 0.
  • the transmittance of the laser light Ln having a normal intensity profile decreases as the offset amount Lo approaches zero. Then, the transmittance of the laser beam Ln is minimized when the offset amount Lo is 0, for example, a loss of about 65%.
  • the transmittance of the laser light L having an annular intensity profile decreases as the offset amount Lo approaches 0, but the offset amount. It becomes flat when Lo is between ⁇ 1 and 1.
  • the transmittance at this time is larger than the transmittance of the normal laser light L, and is only about 40% loss, for example.
  • FIG. 15 the intensity on the optical axis of the annular laser beam L is larger than the intensity on the optical axis of the normal laser beam Ln from the incident surface of the laser beam (in the drawing). Even if “z”) becomes large, it is difficult to attenuate.
  • the laser beam L has less energy loss when passing through the light shielding area SA than the laser beam Ln. For this reason, the energy at the condensing point P of the laser beam L is greater than that of the laser beam Ln immediately below the light shielding area SA.
  • the modified region 7 is sufficiently formed even immediately below the light shielding region SA, and the missing portion M of the modified region 7 is unlikely to occur. This is considered to be a cause of the above effect.
  • the conditions of the experiment for the above consideration are as follows as an example.
  • the outer diameter (beam outer diameter) Do of the intensity profile of the laser beam L on the incident surface of the laser beam L of the objective lens is 2.88 mm.
  • the outer diameter of the laser beam Ln on the incident surface of the laser beam Ln of the objective lens 2.88 mm.
  • the width of the light shielding area SA 1.0 mm.
  • the experiment for the above consideration is not the measurement of the transmittance and the beam diameter in the workpiece 1 but an experiment on the objective lens. This is because it is difficult to measure the transmittance of the workpiece 1.
  • the beam diameter of the laser light L incident on the objective lens was 5.0 mm
  • the pupil diameter of the objective lens was 2.88 mm. Since the beam outer shape Do of the laser light L incident on the objective lens is determined by the pupil diameter of the objective lens, in this case, it is 2.88 mm as described above, and the inner diameter Di is 2.0 mm.
  • the light shielding area SA was formed on the objective lens. For this reason, the width of the light shielding area SA is converted to the width at the entrance surface of the objective lens.
  • the ratio ( ⁇ i) to the width of the shielding area SA is equal between the experiment and the value of the experiment on the workpiece 1. From this, it can be said that the experiment is equivalent to the experiment under the actual condition with the workpiece 1 at least in the above consideration.
  • the condensing point when the laser beam L having an annular intensity profile is condensed to the maximum is compared with the similar condensing point of the laser beam Ln having a normal intensity profile, It has been confirmed that the laser beam L is elongated along the optical axis, and the cross-sectional area along the optical axis is increased.
  • the energy input to the workpiece 1 can be increased at the condensing point of the laser beam L compared to the condensing point of the laser beam Ln.
  • the laser beam L when used, sufficient energy can be input to form the modified region 7 even immediately below the light shielding region SA, and the missing portion M of the modified region 7 can be reduced. Hard to occur. This is considered to be another cause of the above effect.
  • the processing object 1 has a semiconductor layer 22 for a semiconductor laser containing gallium nitride.
  • the semiconductor layer 22 includes a main surface 22s.
  • the light shielding area SA is a stripe-shaped high-density defect area provided in the semiconductor layer 22 so as to extend in a direction intersecting the planned cutting line 5a.
  • the planned cutting line 5 a is set along the cleavage planes of the substrate 21 and the semiconductor layer 22.
  • the semiconductor layer 22 for the semiconductor laser and the cutting scheduled line 5a set along the cleavage plane of the substrate 21 are as described above. It is possible to form the modified region 7 so that the missing portion M does not occur. For this reason, it is possible to suppress the deterioration of the cut surface (cleavage surface) and to reliably realize the mirror surface of the cut surface.
  • the intensity profile of the laser beam L is made annular by the spatial light modulator 122 presenting a predetermined modulation pattern. For this reason, by controlling a predetermined modulation pattern of the spatial light modulator 122, the annular shape of the intensity profile of the laser light L can be dynamically changed. Therefore, it is possible to form an appropriate modified region 7 according to the material of the workpiece 1 and the required cutting accuracy.
  • the above embodiment has been described as an embodiment of the processing object cutting method according to one aspect of the present invention. Therefore, the workpiece cutting method according to one aspect of the present invention is not limited to the above embodiment.
  • the processing object cutting method according to one aspect of the present invention can arbitrarily change the above-described form without changing the gist of each claim.
  • the processing target in the processing target cutting method according to one aspect of the present invention is not limited to the processing target 1 described above. That is, the object to be processed does not include the semiconductor layer 22 (semiconductor layer 12) for the semiconductor laser containing gallium nitride, and may be, for example, TEG. Further, the light shielding area SA is not limited to the high density defect area but may be a wiring or the like. That is, the object to be processed can be an arbitrary object provided with an arbitrary shielding region with respect to the incident surface of the laser beam.
  • the optical system 113 only needs to have a function for making the intensity profile of the laser light L into an annular shape, and is not limited to one using the spatial light modulator 122.
  • the optical system 113 may use an axicon lens pair.
  • the optical system 113 may use a mask member that is provided for the condenser lens 105 and shields the central portion of the beam spot of the laser light L in a circular shape.
  • the mask member may be provided directly on the incident surface of the laser beam L of the condensing lens 105, or may be held away from the incident surface.
  • the processing object cutting method according to the present embodiment is effective not only for a processing object having a light shielding area on the incident surface as described above but also for a processing object having no light shielding area. It has been confirmed that. That is, even if the workpiece does not have a light shielding area, if a laser beam having a normal intensity profile is collected and irradiated, a missing part of the modified area may suddenly occur. is there. On the other hand, according to the workpiece cutting method according to the present embodiment, it is possible to reduce the occurrence of such a sudden missing portion of the modified region and suppress the deterioration of the cut surface.
  • the intensity profile Pa of the laser beam L is an annular shape.
  • the intensity profile Pa may be an annular shape to the last, and is not limited to the case where both the outer edge and the inner edge are perfect circles. Another example of the annular intensity profile Pa will be described.
  • FIG. 16 is a diagram showing a modification of the annular intensity profile.
  • FIG. 16A shows a case where the outer edge Co and the inner edge Ci of the intensity profile Pa are both perfect circles as described above.
  • FIGS. 16B to 16D show examples in which the outer edge Co is a perfect circle and the inner edge Ci is an ellipse.
  • the major axes of the ellipses of the inner edge Ci are arranged so as to intersect (orthogonal) each other.
  • the major axis of the ellipse of the inner edge Ci is inclined.
  • FIG. 17 is a diagram showing another modification of the annular intensity profile.
  • the outer edge Co of the intensity profile Pa is an ellipse.
  • the inner edge Ci is a perfect circle.
  • the outer edge Co and the inner edge Ci are both elliptical.
  • the major axes of the ellipses of the inner edge Ci are arranged so as to intersect (orthogonal) each other.
  • the major axis of the ellipse of the inner edge Ci is inclined.
  • FIG. 18 is a diagram showing another modification of the annular intensity profile.
  • the outer edge Co of the intensity profile Pa is an ellipse.
  • the ellipse of the outer edge Co is inclined.
  • the inner edge Ci is a perfect circle.
  • the outer edge Co and the inner edge Ci are both elliptical.
  • the major axes of the ellipses of the inner edge Ci are arranged so as to intersect (orthogonal) each other.
  • FIG. 18D the major axis of the ellipse of the inner edge Ci is inclined.
  • FIG. 19 is a diagram showing another modification of the annular intensity profile.
  • the outer edge Co and the inner edge Ci are both elliptical, and their centers (axes) do not coincide.
  • the outer edge Co is a perfect circle and the inner edge Ci is an ellipse.
  • the major axis of the ellipse of the inner edge Ci is made larger than the diameter of the perfect circle of the outer edge Co.
  • a plurality of (here, two) elliptical inner edges Ci are included for a single outer edge Co.
  • the annular intensity profile Pa of the laser beam L only needs to be formed into a ring including a ring or a partial ring by a circular outer edge and inner edge including a perfect circle and an ellipse. In either case, the same effects as in the above embodiment can be obtained.
  • SYMBOLS 1 Processing object, 5a ... Planned cutting line, 7 ... Modified area

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Laser Beam Processing (AREA)
  • Dicing (AREA)

Abstract

La présente invention porte sur un procédé de découpe d'un objet à traiter, comprenant : une première étape consistant à amener la lumière laser à entrer dans une lentille de condensation de lumière ; et une seconde étape consistant à former une région reformée dans l'objet à traiter le long d'une ligne de découpe prévue en amenant un point de condensation de lumière à se déplacer relativement le long de la ligne de découpe prévue tout en utilisant la lentille de condensation de lumière pour amener la lumière laser à être condensée à l'intérieur de l'objet à traiter. Une région d'arrêt de la lumière chevauche une partie de la ligne de coupe prévue. Dans la première étape, la lumière laser est amenée à entrer dans la lentille de condensation de lumière à l'aide d'un profil d'intensité de lumière laser en forme d'anneau. Dans la seconde étape, un plan principal est amené à être le plan d'entrée pour la lumière laser, et le point de condensation de lumière est déplacé relativement le long de la ligne de découpe prévue de manière à traverser la région d'arrêt de la lumière.
PCT/JP2017/001422 2016-01-20 2017-01-17 Procédé de découpe d'un objet à traiter WO2017126506A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020027856A (ja) * 2018-08-10 2020-02-20 ローム株式会社 ＳｉＣ半導体装置
US11626490B2 (en) 2018-08-10 2023-04-11 Rohm Co., Ltd. SiC semiconductor device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009021476A (ja) * 2007-07-13 2009-01-29 Disco Abrasive Syst Ltd ウエーハの分割方法
JP2011152561A (ja) * 2010-01-27 2011-08-11 Hamamatsu Photonics Kk レーザ加工方法
WO2014156692A1 (fr) * 2013-03-27 2014-10-02 浜松ホトニクス株式会社 Dispositif d'usinage laser et procédé d'usinage laser

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009021476A (ja) * 2007-07-13 2009-01-29 Disco Abrasive Syst Ltd ウエーハの分割方法
JP2011152561A (ja) * 2010-01-27 2011-08-11 Hamamatsu Photonics Kk レーザ加工方法
WO2014156692A1 (fr) * 2013-03-27 2014-10-02 浜松ホトニクス株式会社 Dispositif d'usinage laser et procédé d'usinage laser

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020027856A (ja) * 2018-08-10 2020-02-20 ローム株式会社 ＳｉＣ半導体装置
US11626490B2 (en) 2018-08-10 2023-04-11 Rohm Co., Ltd. SiC semiconductor device
US12021120B2 (en) 2018-08-10 2024-06-25 Rohm Co., Ltd. SiC semiconductor device

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JP6752232B2 (ja) 2020-09-09
TW201738027A (zh) 2017-11-01
TWI705867B (zh) 2020-10-01

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