JP7055647B2 - Cutting method - Google Patents

Description

The present invention relates to a cutting method and a chip.

The β-Ga ₂ O ₃ crystal has a (100) plane as a highly cleavable plane. Therefore, the β-Ga ₂ O ₃ substrate has a property that cleavage is likely to occur along the (100) plane when the β-Ga 2 O 3 substrate is separated by blade dicing. Generally, in order to prevent cleavage, a means of lowering the cutting rate can be taken, but in order to prevent cleavage of the Ga ₂ O ₃ substrate, the cutting rate is set to a very small value (for example, 0.1 mm / sec or more). It is necessary to set it to 0.3 mm / sec), which consumes a very long time in the cutting process.

Further, conventionally, a method of forming a modified region inside a substrate by laser light to separate the substrate is known (see, for example, Patent Documents 1 and 2). The modified region is a region formed by moving the focusing point of the laser light along the planned cutting line of the substrate, and when the modified region is appropriately formed, an external force is applied to the substrate. This makes it possible to break the substrate along the planned cutting line.

Japanese Unexamined Patent Publication No. 2008-68319 International Publication No. 2008/146744

However, in the case of separating a substrate including a cleavage surface having strong cleavage such as a Ga ₂ O ₃ system substrate, even with the methods described in Patent Documents 1 and 2, the separation is performed by applying an external force. At that time, cleavage may occur on a surface different from the desired surface.

Therefore, an object of the present invention is to provide a cutting method and a chip capable of cutting a processed object containing gallium oxide at a high speed while suppressing the influence of cleavage.

The cutting method according to the present invention is a cutting method having a first surface and a second surface opposite to the first surface, and cutting an object to be processed containing gallium oxide along a planned cutting line. The first step and the first step of forming a modified region in the work object along the cut line by irradiating the work object with the laser light along the cut line with the surface as the incident surface of the laser light. After that, a second step of cutting the machining object along the scheduled cutting line by inserting a cutting tool into the machining target along the scheduled cutting line is provided, and one cutting schedule is provided in the first step. A modification containing a plurality of rows of modified regions by forming at least a plurality of rows of modified regions with respect to the line so as to intersect the planned cutting line and be arranged in the first direction along the first surface. Form a pawnbroker.

In this cutting method, the processing target to be cut contains gallium oxide. Therefore, when cutting the workpiece by blade dicing as described above, it is necessary to reduce the cutting rate. Further, when cutting is performed from the modified region by applying an external force to the object to be processed, the influence of the cleaved surface of gallium oxide is likely to occur. On the other hand, in this cutting method, in the first step, a reforming region is formed along the scheduled cutting line, and in the second step, the cutting tool is inserted into the object to be machined along the scheduled cutting line. This cuts the object to be processed. In this way, by performing cutting in a state of being brittle due to the formation of the modified region (for example, the crystallinity of gallium oxide is reduced), it is possible to cut the workpiece while suppressing the influence of cleavage. .. In particular, in the first step, a reforming portion including a plurality of rows of reforming regions is formed for one scheduled cutting line. Therefore, it is possible to cut the modified portion at high speed by using a cutting tool having a certain width. Therefore, according to this cutting method, it is possible to cut a work object containing gallium oxide at high speed while suppressing the influence of cleavage.

In the cutting method according to the present invention, in the first step, a plurality of rows of modified regions are formed so as to be arranged in the second direction from the second surface to the first surface for one planned cutting line. This may form a modified portion. In this case, since the modified portion extends in the thickness direction (second direction) of the object to be processed, it is possible to cut at a higher speed while surely suppressing the influence of cleavage.

In the cutting method according to the present invention, in the first step, a plurality of rows of modified regions are formed while maintaining the positions of the focusing points of the laser light in the second direction, and the modified regions including the plurality of rows are included. By repeating the step of forming the modified layer for forming the layer while changing the position of the condensing point of the laser beam in the second direction, the modified portion including the plurality of modified layers may be formed. In this way, if the modified portion is configured by laminating the modified layer along the thickness direction (second direction) of the object to be processed, the shape and state of the modified portion can be controlled with respect to the thickness direction. It will be easy.

In the cutting method according to the present invention, in the first step, the modified layer forming step is repeated while changing the position of the focusing point of the laser beam in the second direction from the second surface side to the first surface side in order. May form a modified portion including a plurality of modified layers. In this case, since the modified region is formed from the second surface side opposite to the first surface which is the incident surface of the laser beam, the modified region is not affected by the previously formed modified region. It is possible to form a modified region of.

In the cutting method according to the present invention, in the first step, the modified region may be formed so that the width of the modified portion in the first direction is larger than the width of the cutting tool in the first direction. In this case, the effect of cleavage can be suppressed more reliably.

In the cutting method according to the present invention, in the first step, a modified region may be formed so that the modified portion continuously extends from one end to the other end of the object to be processed along the planned cutting line. .. In this case, it is possible to cut the entire length of the object to be machined while surely suppressing the influence of cleavage.

The chip according to the present invention is formed on the first surface, a second surface opposite to the first surface, and a gallium oxide substrate having a side surface connecting the first surface and the second surface. The device layer is provided, and the side surface is composed of a modified region.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a cutting method and a chip capable of cutting a processed object containing gallium oxide at a high speed while suppressing the influence of cleavage.

It is a schematic block diagram of the laser processing apparatus used for forming a reforming region. It is a top view of the processing object which is the object of formation of the modification region. FIG. 3 is a cross-sectional view taken along the line III-III of the object to be processed in FIG. It is a top view of the machined object after laser machining. It is sectional drawing along the VV line of the processing object of FIG. FIG. 6 is a cross-sectional view taken along the line VI-VI of the object to be machined in FIG. It is a figure which shows the processing object to be cut by the cutting method which concerns on this embodiment. It is an enlarged perspective view for demonstrating the outline of the cutting method which concerns on this Embodiment. It is a schematic cross-sectional view of the processing object shown in FIG. 8 (a). It is a figure which shows the 1st process. It is a figure which shows the 1st process. It is a figure which shows the relationship between a reforming part and a cutting tool. It is a perspective view which shows the chip formed by the cutting method which concerns on this embodiment. It is sectional drawing which shows the modification of the modification part. It is sectional drawing which shows the modification of the modification part.

Hereinafter, an example of the method and the apparatus according to the present embodiment will be described with reference to the drawings. In the description of the drawings, the same elements or the corresponding elements may be designated by the same reference numerals, and duplicate description may be omitted.

In the laser processing apparatus according to the embodiment, a modified region is formed on the processing target along the planned cutting line by condensing the laser light on the processing target. Therefore, first, the formation of the modified region will be described with reference to FIGS. 1 to 6.

As shown in FIG. 1, the laser processing apparatus 100 includes a laser light source 101 that pulse-oscillates the laser beam L, and a dichroic mirror 103 arranged so as to change the direction of the optical axis (optical path) of the laser beam L by 90 °. A condensing lens 105 for condensing the laser beam L is provided. Further, the laser processing apparatus 100 moves the support base 107 for supporting the processing target object 1 which is the object to be irradiated with the laser beam L focused by the light collecting lens 105, and the support base 107. Stage 111, which is a moving mechanism of the laser beam L, a laser light source control unit 102 that controls the laser light source 101 to adjust the output, pulse width, pulse waveform, etc. of the laser beam L, and a stage control unit 115 that controls the movement of the stage 111. And have.

In the laser processing apparatus 100, the laser beam 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 inside the processing object 1 placed on the support base 107. The light is collected by the light collecting lens 105. At the same time, the stage 111 is moved, and the workpiece 1 is moved relative to the laser beam L along the planned cutting line 5. As a result, a modified region along the scheduled cutting line 5 is formed on the workpiece 1. Here, although the stage 111 is moved in order to relatively move the laser beam L, the condensing lens 105 may be moved, or both of them may be moved.

As the object to be processed 1, a plate-shaped member (for example, a substrate, a wafer, etc.) including a semiconductor substrate formed of a semiconductor material, a piezoelectric substrate formed of a piezoelectric material, or the like is used. As shown in FIG. 2, the machined object 1 is set with a scheduled cutting line 5 for cutting the machined object 1. The line 5 to be cut is a virtual line extending in a straight line. When forming a modified region inside the object to be processed 1, as shown in FIG. 3, the laser beam L is cut while the condensing point (condensing position) P is aligned with the inside of the object to be processed 1. It is relatively moved along the planned line 5 (that is, in the direction of arrow A in FIG. 2). As a result, as shown in FIGS. 4, 5 and 6, the reformed region 7 is formed on the workpiece 1 along the scheduled cutting line 5, and the modified region formed along the scheduled cutting line 5. 7 becomes the cutting starting point region 8. The scheduled cutting line 5 corresponds to the scheduled irradiation line.

The condensing point P is a point where the laser beam L condenses. 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 are combined, or a coordinate-designated line 5. The line 5 to be cut is not limited to a virtual line, but may be a line actually drawn on the surface 3 of the object to be machined 1. The modified region 7 may be formed continuously or intermittently. The modified region 7 may be in a row or a dot shape, and in short, the modified region 7 may be formed at least inside the workpiece 1 or on the front surface 3 or the back surface. Cracks may be formed starting from the modified region 7, and the cracks and the modified region 7 may be exposed on the outer surface (front surface 3, back surface, or outer peripheral surface) of the object to be processed 1. The laser beam incident surface when forming the modified region 7 is not limited to the surface 3 of the object to be processed 1, and may be the back surface of the object to be processed 1.

By the way, when the modified region 7 is formed inside the object to be processed 1, the laser beam L passes through the object 1 to be processed and is located in the vicinity of the condensing point P located inside the object 1 to be processed. Especially absorbed. As a result, the modified region 7 is formed on the object to be machined 1 (that is, internal absorption type laser machining). In this case, since the laser beam L is hardly absorbed by the surface 3 of the object to be processed 1, the surface 3 of the object to be processed 1 is not melted. On the other hand, when the modified region 7 is formed on the front surface 3 or the back surface of the object 1 to be processed, the laser beam L is particularly absorbed in the vicinity of the condensing point P located on the front surface 3 or the back surface, and the front surface 3 or the back surface 3 or the back surface. It is melted and removed from the surface to form a removed portion such as a hole or groove (surface absorption type laser processing).

The modified region 7 refers to a region in which the density, refractive index, mechanical strength and other physical properties are different from those of the surroundings. The modified region 7 includes, for example, a melting treatment region (meaning at least one of a region once melted and then resolidified, a region in a molten state, and a region in a state of being resolidified from melting) and a crack region. , Dielectric breakdown region, refractive index change region, etc., and there is also a region where these are mixed. Further, the modified region 7 includes a region in which the density of the modified region 7 in the material of the object to be processed 1 changes as compared with the density of the non-modified region, and a region in which lattice defects are formed. When the material of the object to be processed 1 is single crystal silicon, the modified region 7 can be said to be a high dislocation density region.

The melt-treated region, the refractive index change region, the region where the density of the modified region 7 changes as compared with the density of the non-modified region, and the region where the lattice defect is formed are further inside those regions and modified. Cracks (cracks, microcracks) may be included at the interface between the region 7 and the non-modified region. The included cracks may extend over the entire surface of the modified region 7, or may be formed only in a part or in a plurality of parts. The object to be processed 1 includes a substrate made of a crystalline material having a crystal structure. For example, the object to be processed 1 is at least one of gallium oxide (Ga ₂ O ₃ ), gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO ₃ , and sapphire (Al ₂ O ₃ ). Includes the formed substrate. In other words, the object to be processed 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. Further, the object to be processed 1 may include a substrate made of a non-crystalline material having a non-crystalline structure (amorphous structure), and may include, for example, a glass substrate.

In the embodiment, the modified region 7 can be formed by forming a plurality of modified spots (machining marks) along the planned cutting line 5. In this case, the reformed region 7 is formed by gathering a plurality of reformed spots. The modified spot is a modified portion formed by one pulse shot of pulsed laser light (that is, one pulse laser irradiation: laser shot). Examples of the modified spot include crack spots, melt-treated spots, refractive index change spots, and spots in which at least one of these is mixed. For the modified spot, the size and the length of the cracks that occur are appropriately adjusted in consideration of the required cutting accuracy, the required flatness of the cut surface, the thickness, type, crystal orientation, etc. of the workpiece 1. Can be controlled. Further, in the embodiment, the reforming spot can be formed as the reforming region 7 along the planned cutting line 5.
[Cutting method according to the embodiment]

Subsequently, the cutting method according to the embodiment will be described. FIG. 7 is a diagram showing a work object to be cut by the cutting method according to the present embodiment. FIG. 7A is a plan view, and FIG. 7B is a partial cross-sectional view. The object to be processed 1 shown in FIG. 7 contains gallium oxide (for example, Ga ₂ O ₃ ). More specifically, the object to be processed 1 includes a substrate 11 containing gallium oxide and a device layer 12 formed on the substrate 11. The substrate 11 includes a first surface 11s (eg, surface 3 in FIG. 1) and a second surface 11r opposite the first surface 11s.

The substrate 11 is, for example, a gallium oxide substrate (for example, a Ga ₂ O ₃ system substrate). The Ga ₂ O ₃ system substrate is a β-type (Al _{x Gay In z ) 2} O ₃ (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y + z = 1) single crystal. It is a substrate made of a β _- Ga ₂ O3 system single crystal to be crystallized, and may contain impurities such as Cu, Ag, Zn, Cd, Al, In, Si, Ge, Sn, Mg, Nb, and Fe. .. The Ga ₂ O ₃ system substrate has a strong cleavage property on the (100) surface, and when the main surface (for example, the first surface 11s) is the (100) surface, peeling occurs and the main surface is other than the (100) surface. If it is a surface, cleavage is likely to occur. Therefore, the cutting method according to the present embodiment is effective regardless of the plane orientation of the main surface of the Ga ₂ O ₃ system substrate.

The device layer 12 is formed on the first surface 11s. The device layer 12 is, for example, a semiconductor operating layer formed by crystal growth, and includes a plurality of device units 13 arranged two-dimensionally on the first surface 11s. The device unit 13 is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, or a circuit element formed as a circuit. A street ST, which is a region where the first surface 11s is exposed, is provided between the device portions 13 adjacent to each other. Street STs are provided, for example, in a grid pattern. The line 5 scheduled to be cut is set to the street ST. That is, the scheduled cutting lines 5 are set in a two-dimensional grid pattern so as to pass between the device portions 13 adjacent to each other.

FIG. 8 is an enlarged perspective view for explaining the outline of the cutting method according to the present embodiment. FIG. 9 is a schematic cross-sectional view of the object to be processed shown in FIG. 8 (a). In FIGS. 8 and 9, only the portion of the object to be machined 1 corresponding to the edge of the pair of device portions 13 and the portion corresponding to the street ST between the pair of device portions 13 are shown. Further, in the following drawings, the modified region 7 may be shown by hatching, and the hatching of other portions may be omitted. Further, in the following drawings, an orthogonal coordinate system defined by the X-axis, the Y-axis, and the Z-axis is shown for ease of understanding.

As shown in FIGS. 8 and 9, in the cutting method according to the present embodiment, the first step of forming the reformed region 7 in the workpiece 1 along the scheduled cutting line 5 and the cutting after the first step. A second step of cutting the machining object 1 along the scheduled cutting line 5 by inserting the cutting tool 50 into the machining object 1 along the scheduled line 5 is included. In the first step, as will be described in detail later, the laser beam L is applied to the object to be machined 1 (substrate 11) along the planned cutting line 5 while the first surface 11s is the incident surface of the laser beam L. , A modified region 7 is formed in the workpiece 1 along the planned cutting line 5.

The laser beam L is an ultrashort pulse laser beam. More specifically, for example, the repetition frequency of the laser beam L is 200 kHz, the center wavelength of the laser beam L is 1030 nm, and the pulse width of the laser beam L is 10 ps or less (for example, several 100 fs or more and 10 ps or less).

In the first step, one scheduled cutting line 5 is arranged so as to intersect (orthogonally) the scheduled cutting line 5 and be arranged in the first direction (here, the Y-axis direction) along the first surface 11s. By forming the modified regions 7 in a plurality of rows (for example, 25 rows, 5 rows in the illustrated example), the modified portion 70 including the modified regions 7 in a plurality of rows is formed. The modified region 7 is in the first direction and in the third direction (here, the X-axis direction) intersecting (orthogonal) in the second direction (here, the Z-axis direction) from the second surface 11r to the first surface 11s. It is formed in a row along the line. Further, in the first step, a plurality of rows (for example, 9 rows, 5 rows in the illustrated example) of modified regions 7 are formed so as to be arranged in the second direction with respect to one scheduled cutting line 5. As a result, a reforming portion 70 including a plurality of rows of reforming regions 7 is formed. As a result, the reforming unit 70 includes a plurality of reforming regions 7 arranged in a matrix along the first direction and the second direction in the cross section intersecting (orthogonal) with the planned cutting line 5. ..

From one point of view, the reforming unit 70 is configured by arranging row-shaped reforming regions 7 extending along the third direction along the second direction (that is, along the second and third directions). It is considered that the modified layer 7m (extending) is configured by laminating a plurality of modified layers in the first direction. From another point of view, the reforming section 70 is configured by arranging row-shaped reforming regions 7 extending along the third direction along the first direction (that is, the first direction and the third). It can also be considered that the modified layer 7n (extending along the direction) is configured by laminating a plurality of modified layers 7n in the second direction. Here, the reforming portion 70 is formed in a rectangular parallelepiped shape extending along the third direction. In addition, in FIG. 9 and the following figures, from the viewpoint of facilitation of illustration, the modified regions 7 adjacent to each other are shown so as to be separated from each other, but the modified regions 7 are partially or wholly separated from each other. They may be formed continuously from each other.

Subsequently, the first step will be described in detail. 10 and 11 are views showing the first step. In FIG. 10B and FIG. 11B, the device unit 13 is omitted. In the first step, as shown in FIG. 10A, first, the first surface 11s is the incident surface of the laser beam L, and the condensing point P of the laser beam L is the object 1 to be processed (base 11). It is located inside the surface or on the second surface 11r. Then, as shown in FIG. 10B, the condensing point P of the laser beam L is moved relative to the workpiece 1, so that the laser beam L is irradiated (scanned) on the object 1 to be processed. ). As a result, as shown in FIG. 11, the modified region 7 is formed in the workpiece 1. Here, the modified region 7 is formed by scanning the workpiece 1 using the stage 111 while irradiating the laser beam L. The scan speed (speed of relative movement of the focusing point P) is 500 mm / sec or less, more preferably 100 mm / sec or less.

In the first step, as shown in FIG. 10B, the focusing point P is set along the first direction and the third direction while maintaining the position of the focusing point P of the laser beam L in the second direction. And move relative to each other. As a result, as shown in FIGS. 11A and 11B, the modified regions 7 having a plurality of rows are included by forming the modified regions 7 having a plurality of rows arranged along the first direction. The modified layer 7n is formed (modified layer forming step).

Subsequently, in the first step, the modified layer 7n is modified so as to be laminated by repeating the above-mentioned modified layer forming step while changing the position of the condensing point P of the laser beam L in the second direction. A region 7 is formed, and a modified portion 70 including a plurality of modified layers 7n is formed (see FIG. 9). In particular, in the first step, the modified layer forming step is repeated while changing the position of the condensing point P of the laser beam L in the second direction from the second surface 11r side to the first surface 11s side in order. As a result, the modified layers 7n are laminated in order from the second surface 11r side. Further, in the first step, the reforming portion 70 forms the reforming region 7 so as to be exposed on both the first surface 11s and the second surface 11r. That is, here, the reforming portion 70 extends continuously along the second direction to form the reforming region 7 so as to reach the first surface 11s and the second surface 11r. Further, in the first step, the reforming region 7 is formed so that the reforming portion 70 continuously extends from one end to the other end of the workpiece 1 along the planned cutting line 5.

After the above first step, the second step is carried out. In the second step, as described above, the machining object 1 is cut along the scheduled cutting line 5 by inserting the cutting tool 50 into the machining object 1 along the scheduled cutting line 5. The cutting tool 50 is, for example, a blade used for blade dicing, and includes a disk-shaped main body portion 51 and a blade portion 52 having a tapered cross section provided on the outer peripheral portion of the main body portion 51. In the second step, while rotating such a cutting tool 50 with the center of the main body 51 as a rotation axis, the blade portion 52 is brought into contact with the machining object 1 (base plate 11) along the planned cutting line 5. insert. As a result, by cutting (removing) a part of the object to be machined 1, the object to be machined 1 is cut along the scheduled cutting line 5.

Here, as shown in FIG. 12, in the first step, the reforming region 7 is formed while defining the dimensions and the shape of the reforming portion 70 in relation to the cutting tool 50. To specify the dimensions and shape of the reforming portion 70 from the relationship with the cutting tool 50 is the state of the portion of the object to be machined 1 that is cut (removed) by the cutting tool 50 (whether or not the whole is modified, etc.). ) Will be specified. In the present embodiment, in the first step, the reforming region 7 is such that the width W70 of the reforming portion 70 in the first direction is larger than the width W50 of the cutting tool 50 (main body portion 51) in the first direction. To form. Therefore, here, the portion of the object 1 to be machined that is cut (removed) by the cutting tool 50 is a region that has been entirely modified.

As a result, a chip is formed from the object to be machined 1. FIG. 13 is a perspective view showing a chip formed by the cutting method according to the present embodiment. As shown in FIG. 13, the chip C includes a substrate 11C formed from the substrate 11 and a device layer 12C (device unit 13) formed from the device layer 12. The substrate 11C is, for example, a gallium oxide substrate. Further, the substrate 11C includes a first surface 11s and a second surface 11r on the opposite side of the first surface 11s, similarly to the substrate 11. Further, the substrate 11C includes a side surface 11p connecting the first surface 11s and the second surface 11r. Here, the surfaces other than the first surface 11s and the second surface 11r in the substantially rectangular parallelepiped substrate 11C are the side surfaces 11p.

As described above, the width W70 of the reforming portion 70 is larger than the width W50 of the cutting tool 50, and the entire region cut (removed) by the cutting tool 50 in the machining object 1 is the reformed region 7 (modified). Quality part 70). Therefore, the modified region 7 remains on the cut surface of the object to be processed 1. In other words, the side surface 11p, which is a cut surface, is composed of a modified region 7 (a part 70C of the modified portion 70) over the entire surface. Further, the side surface 11p is rougher than the cut surface or the cleavage surface obtained by cutting the crack extending from the modified region 7 by the external stress due to the cutting mark of the cutting tool 50, for example.

The device layer 12C includes, for example, a homoepitaxial film or a heteroepitaxial film formed on the substrate 11 by epitaxial growth. Further, the device layer 12C may include, for example, an electrode formed on the surface side opposite to the substrate 11C. Further, another electrode or the like may be formed on the second surface 11r of the substrate 11C. The chip C configured as described above is, for example, a semiconductor optical element such as an LED or a semiconductor power device such as a diode or a transistor.

As described above, in the cutting method according to the present embodiment, the processing object 1 (substrate 11) to be cut contains gallium oxide. Therefore, when cutting the workpiece 1 only by blade dicing, it is necessary to reduce the cutting rate. Further, when cutting is performed starting from the modified region 7 by applying an external force to the object 1 to be processed, the influence of the cleaved surface of gallium oxide is likely to occur. On the other hand, in the cutting method according to the present embodiment, the modified region 7 is formed along the scheduled cutting line 5 in the first step, and the processing target is formed along the scheduled cutting line 5 in the second step. The object to be machined 1 is cut by inserting the cutting tool 50 into the object 1.

In this way, by performing cutting in a state of being brittle due to the formation of the modified region 7 (for example, the crystallinity of gallium oxide is reduced), it is possible to cut the workpiece 1 while suppressing the influence of cleavage. Will be. In particular, in the first step, a reforming portion 70 including a plurality of rows of reforming regions 7 is formed for one scheduled cutting line 5. Therefore, the reforming portion 70 can be cut at high speed by using the cutting tool 50 having a constant width W50. Therefore, according to the cutting method according to the present embodiment, the processing object 1 containing gallium oxide can be cut at high speed while suppressing the influence of cleavage. As an example, the speed of cutting (blade dicing) by the cutting tool 50 here can be 10 times or more, or 2 mm / sec or more, which is the conventional speed.

Further, in the cutting method according to the present embodiment, in the first step, a plurality of rows are arranged so as to be arranged in the second direction from the second surface 11r to the first surface 11s with respect to one scheduled cutting line 5. The modified portion 70 may be formed by forming the modified region 7. In this case, since the reforming portion 70 extends in the thickness direction (second direction) of the object to be processed 1, it is possible to cut at a higher speed while surely suppressing the influence of cleavage.

Further, in the cutting method according to the present embodiment, in the first step, a plurality of rows of modified regions 7 are formed while maintaining the position of the condensing point P of the laser beam L in the second direction, and the plurality of rows are modified. By repeating the step of forming the modified layer 7n including the quality region 7 while changing the position of the condensing point P of the laser beam L in the second direction, the modified layer 7n including the plurality of modified layers 7n is included. The quality part 70 is formed. In this way, if the modified portion 70 is configured by laminating the modified layer 7n along the thickness direction (second direction) of the object to be processed 1, the shape of the modified portion 70 with respect to the thickness direction can be formed. The state can be easily controlled.

In particular, in the cutting method according to the present embodiment, in the first step, the position of the condensing point P of the laser beam L in the second direction is modified while being sequentially changed from the second surface 11r side to the first surface 11s side. By repeating the layer formation step, the reformed portion 70 including the plurality of modified layers 7n is formed. Therefore, since the modified region 7 is formed from the second surface 11r side opposite to the first surface 11s which is the incident surface of the laser beam L, the influence of the previously formed modified region 7 It is possible to form the later modified region 7 without receiving the light.

Further, in the cutting method according to the present embodiment, in the first step, the reforming region 7 is provided so that the width W70 of the reforming portion 70 in the first direction is larger than the width W50 of the cutting tool 50 in the first direction. Form. Therefore, a sufficient cutting allowance can be secured and the influence of cleavage can be suppressed more reliably.

Further, in the cutting method according to the present embodiment, in the first step, the reforming region 70 extends continuously from one end to the other end of the workpiece 1 along the planned cutting line 5. 7 is formed. Therefore, it is possible to cut the entire length of the object to be machined 1 while surely suppressing the influence of cleavage.

The above embodiment describes one embodiment of the cutting method according to the present invention. Therefore, the cutting method according to the present invention is not limited to the cutting method described above, and can be arbitrarily modified.

Further, as shown in FIGS. 14 and 15, the shape of the reforming portion 70 in the cross section (cross section along the first direction and the second direction) intersecting the planned cutting line 5 may be changed. In the example of FIG. 14A, the modified region 7 is formed so that the cross-sectional shape of the modified portion 70 has a tapered cross-sectional shape that shrinks from the first surface 11s toward the second surface 11r. are doing. In the example of FIG. 14B, the modified region 7 is formed so that the cross-sectional shape of the modified portion 70 has a tapered cross-sectional shape that expands from the first surface 11s to the second surface 11r. are doing.

Further, in the example of FIG. 15A, the modified region has a cross-sectional shape such that the cross-sectional shape of the modified portion 70 is once reduced and then expanded as it goes from the first surface 11s to the second surface 11r. 7 is formed. In the example of FIG. 15B, the modified region 7 is provided so that the cross-sectional shape of the modified portion 70 has a cross-sectional shape that expands and then contracts as it goes from the first surface 11s to the second surface 11r. Is forming. Further, in the example of FIG. 15 (c), the modified region 7 is formed so that the cross-sectional shape of the modified portion 70 becomes a wavy shape that bends a plurality of times from the first surface 11s to the second surface 11r. There is. As in these examples, the cross-sectional shape of the modified portion 70 can be appropriately selected depending on, for example, the shape of the cutting tool 50. The aspect (for example, shape) of the reforming portion 70 in a plan view can also be appropriately selected depending on, for example, the shape of the cutting tool 50.

In the above embodiment, an example of forming the modified region 7 so that the modified layer 7n extending along the first direction and the third direction is laminated from the second surface 11r side has been described. However, the modified region 7 may be formed so that the modified layers 7n are laminated in order from the first surface 11s side, or the modified layers 7 m extending along the second and third directions are laminated in order. The modified region 7 may be formed in. Furthermore, the modified region 7 may be formed according to another order.

1 ... Processing target, 5 ... Scheduled cutting line, 7 ... Modified region, 7n ... Modified layer, 11C ... Substrate, 11s ... First surface, 11r ... Second surface, 11p ... Side surface, 12C ... Device layer, 50 ... Cutting tool, 70 ... Modified part, C ... Chip, L ... Laser light, P ... Condensing point, W50, W70 ... Width.

Claims (4)

A cutting method having a first surface and a second surface opposite to the first surface, and cutting a work object containing gallium oxide along a planned cutting line.
By irradiating the machined object with the laser beam along the planned cutting line with the first surface as an incident surface of the laser light, a modified region is formed on the machined object along the planned cutting line. 1 step and
After the first step, a second step of cutting the machining object along the cutting schedule line by inserting a cutting tool into the machining object along the cutting schedule line.
Equipped with
In the first step, for one planned cutting line, at least a plurality of rows of modified regions are provided so as to intersect the planned cutting line and be arranged in the first direction along the first surface. By forming, a reformed portion containing the modified region having a plurality of rows is formed .
In the first step, a plurality of rows of the modified regions are formed so as to be arranged in a second direction from the second surface toward the first surface with respect to one planned cutting line. Form a modified part,
In the first step, a plurality of rows of the modified regions are formed while maintaining the positions of the focusing points of the laser light in the second direction to form a modified layer including the plurality of rows of the modified regions. The modified layer forming step is repeated while changing the position of the condensing point of the laser beam in the second direction to form the modified portion including the plurality of modified layers.
Cutting method. In the first step, the modified layer forming step is repeated while sequentially changing the position of the condensing point of the laser beam in the second direction from the second surface side to the first surface side. Forming the modified portion including the plurality of modified layers,
The cutting method according to claim 1 . In the first step, the reforming region is formed so that the width of the reforming portion in the first direction is larger than the width of the cutting tool in the first direction.
The cutting method according to claim 1 or 2 . In the first step, the reformed region is formed so that the reformed portion continuously extends from one end to the other end of the work target along the planned cutting line.
The cutting method according to any one of claims 1 to 3 .

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