Laser processing device and laser processing method

Abstract

Laser processing device (100, 300) comprising: a support table (107) designed to support an object (1) to be processed, which includes a substrate (12) made of a crystalline material; a laser light source (202) designed to emit laser light (L); a converging optical system (204) designed such that the light emitted by the laser light source (202) is converged onto the object (1) to be processed, which is supported by the support table (107); an imaging unit (211) designed to image a front surface (3, 12a) of the object (1) to be processed, which is supported by the support table (107); a candidate line specification unit (250) designed to specify a plurality of candidate lines (5A) extending in different directions for the object (1) to be processed; an operating control unit (250) designed to control the operation of the support table (107), the laser light source (202) and / or the converging optical system (204) such that a modified area (7) is formed inside the substrate (12) along each of the plurality of candidate lines (5A) and a crack (Hc) reaches the front surface (3, 12a) of the object (1) to be processed from the modified area (7); and a reference line defining unit (250) designed to define for the object (1) to be processed a reference line (5B) which is defined as a line indicating a crystal orientation (K) of the substrate (12) on the basis of an image of the crack (Hc) imaged by the imaging unit (211).

Description

Technical field

[0001] One aspect of the present invention relates to a laser processing device and to a laser processing method. Background of the technology

[0002] A technique is known which forms a cutting start point region along each of a plurality of cutting lines defined in a grid pattern for a workpiece containing a substrate made of a crystalline material, and which causes a crack from the cutting start point region to reach the front and rear faces of the workpiece in order to obtain a plurality of chips by cutting the workpiece along each of the plurality of cutting lines (see, for example, patent literature 1). Examples of the cutting start point region include a modified area formed within the substrate, a groove formed on the front face of the workpiece, and the like.

[0003] US 2011 / 0155706A1 relates to a laser processing method for processing a workpiece by irradiating it with a laser beam and a laser processing device that performs this method, in particular for processing starting points for a division in a workpiece.

[0004] JP 2014 - 87 833 A relates to a laser processing device for dividing a patterned substrate in which a multitude of unit patterns are arranged two-dimensionally and repeatedly on a substrate. List of citations from patent literature

[0005] Patent literature 1: Unexamined Japanese patent publication JP 2006 - 108 459 A Overview of the invention Technical problem

[0006] When the majority of chips are obtained by cutting the object to be processed using the technique described above, a height difference occurs in some cases at the cut surface of the chip, and the chip yield is reduced. The inventors of the present invention have found that the occurrence of this height difference is caused by the fact that the cutting line is set in such a way that it deviates with respect to the crystal orientation of the substrate of the object to be processed.

[0007] One objective of the present invention is to provide a laser processing device and a laser processing method that are able to prevent a cutting line from deviating and being fixed with respect to the crystal orientation of the substrate of the object to be processed. Solution to the problem

[0008] A laser processing device according to one aspect of the present invention comprises: a support table configured to carry an object to be processed, which includes a substrate made of a crystalline material; a laser light source configured to emit laser light; a converging optical system configured to converge the light emitted by the laser light source onto the object to be processed, which is carried by the support table; an imaging unit configured to image a front surface of the object to be processed, which is carried by the support table; a candidate line defining unit configured to define a plurality of candidate lines for the object to be processed, which extend in different directions from one another;an operating control unit designed to control the operation of the support stage, the laser light source and / or the converging optical system such that a modified area is formed inside the substrate along each of the plurality of candidate lines and a crack reaches the front face of the object to be processed from the modified area; and a reference line setting unit designed to set a reference line for the object to be processed, which is determined as a line indicating a crystal orientation of the substrate, based on an image of the crack imaged by the imaging unit.

[0009] The inventors of the present invention have found that when the cutting start point region is formed along the candidate line and the object to be processed is cut from the cutting start point region as the starting point, the number of height differences occurring at the cut surface of the object to be processed increases with increasing degree of crack deflection with respect to the candidate line. In light of this finding, in the laser processing device of the present invention, the reference line (the line indicating the crystal orientation of the substrate) for the object to be processed is defined, the reference line being determined based on the image of the crack that reaches the front surface of the object to be processed from the modified region along each of the plurality of candidate lines extending in different directions.Accordingly, it is possible to define the cutting line for the object to be processed, which extends in a direction parallel to the reference line. Therefore, with the laser processing device of the present invention, it is possible to prevent the cutting line from deviating with respect to the crystal orientation of the substrate of the object to be processed and to define it.

[0010] In the laser processing device according to one aspect of the present invention, the candidate line definition unit can define a predetermined number of candidate lines for the object to be processed, extending in different predetermined directions, and the reference line definition unit can select a candidate line from the predetermined number of candidate lines for the object to be processed, which exhibits the smallest degree of crack deflection, as the reference line. In this case, it is sufficient for laser irradiation, confirmation of the crack's condition, and the like to be performed only for the predetermined number of candidate lines extending in different predetermined directions, so that defining the reference line for the object to be processed can be carried out easily.

[0011] In the laser processing device according to one aspect of the present invention, the candidate line determination unit for the object to be processed can define the predetermined number of candidate lines, extending in different predetermined directions, using an orientation surface with which the object to be processed is equipped as a reference. In this case, variations in the determination of the candidate lines for each object to be processed can be prevented.

[0012] In the laser processing device according to one aspect of the present invention, the candidate line determination unit can successively determine the plurality of candidate lines for the object to be processed based on the image of the crack generated by the imaging unit, until the degree of crack deflection falls within a predetermined range. The reference line determination unit can then define one of the candidate lines whose degree of crack deflection falls within the predetermined range as the reference line for the object to be processed. In this case, it is possible to determine the reference line for the object to be processed with the desired accuracy.

[0013] In the laser processing device according to one aspect of the present invention, the candidate line determination unit for the object to be processed can define an initial candidate line using an orientation surface as a reference, with which the object to be processed is equipped. In this case, variations in the determination of the candidate lines for each object to be processed can be prevented.

[0014] The laser processing device according to one aspect of the present invention can further include a storage unit that pre-stores a relationship between an angle formed by the candidate line with respect to the crystal orientation and a degree of crack deflection. In a case where the majority of candidate lines are successively defined for the object to be processed, it is possible, when a new candidate line is defined using the relationship as an index, to reduce the number of candidate lines that need to be defined until the degree of crack deflection falls within the predetermined range.

[0015] The laser processing device according to one aspect of the present invention can further include a display unit designed to show the image of the crack as captured by the imaging unit. In this case, an operator can confirm the condition of the crack and the like.

[0016] In the laser device according to one aspect of the present invention, the operating control unit can control the operation of the support table, the laser light source, and / or the converging optical system such that a reference mark indicating the crystal orientation is formed on the object to be processed along the reference line defined by the reference line definition unit. In this case, it is possible to use the reference mark as a reference to define the cutting line, which extends in the direction parallel to the reference line, for the object to be processed.

[0017] The laser processing device according to one aspect of the present invention may further include a cutting line definition unit designed to define a cutting line for the object to be processed, which extends in a direction parallel to the reference line defined by the reference line definition unit, wherein the operating control unit controls the operation of the support table, the laser light source and / or the converging optical system such that the modified area inside the substrate is formed along the cutting line defined by the cutting line definition unit.In this case, a series of steps can be performed in a laser processing device, such as laser irradiation along the candidate line, confirmation of the crack condition, determination of the reference line, determination of the cutting line, and laser irradiation along the cutting line.

[0018] A laser processing method according to one aspect of the present invention comprises: a first step for defining a plurality of candidate lines extending in different directions for a processing object comprising a substrate made of a crystalline material; a second step for converging a laser light onto the processing object such that a modified region is formed inside the substrate along each of the plurality of candidate lines and a crack reaches a front face of the processing object from the modified region; and a third step for defining a reference line for the processing object, which is determined as a line indicating a crystal orientation of the substrate based on a state of the crack.

[0019] With the laser light method according to one aspect of the present invention, it is possible, for the same reason as with the laser processing device of the present invention described above, to prevent the cutting line from deviating and being fixed with regard to the crystal orientation of the substrate of the object to be processed.

[0020] In the laser processing method according to one aspect of the present invention, in the first step a predetermined number of candidate lines extending in different predetermined directions can be defined for the object to be processed, and in the third step a candidate line exhibiting the smallest degree of crack deflection can be selected from the predetermined number of candidate lines as the reference line for the object to be processed. In this case, it is sufficient to perform laser irradiation, confirmation of the crack's condition, and the like only for the predetermined number of candidate lines extending in different predetermined directions, thus simplifying the definition of the reference line for the object to be processed.

[0021] In the laser processing method according to one aspect of the present invention, in the first step, based on the state of the crack, a plurality of candidate lines can be successively defined for the object to be processed until the degree of crack deflection falls within a predetermined range. In the third step, one of the candidate lines whose degree of crack deflection falls within the predetermined range can be defined as the reference line for the object to be processed. In this case, it is possible to define the reference line for the object to be processed with the desired accuracy.

[0022] In the laser processing device according to one aspect of the present invention, the candidate line definition unit can define the plurality of candidate lines for the object to be processed, which have different angles formed with respect to a reference direction; the reference line definition unit can detect an inclination direction in which the crack of each of the plurality of candidate lines is inclined with respect to a corresponding candidate line; the reference line definition unit can define the reference line for the object to be processed based on a first candidate line, the inclination direction of which of the crack is on one side of a corresponding candidate line and which has a smallest or largest angle formed with respect to the reference direction, and a second candidate line.whose crack inclination direction is located on another side of a corresponding candidate line and which has a smallest or largest angle with respect to the reference direction, from the majority of candidate lines.

[0023] In the laser processing method according to one aspect of the present invention, in the first step, the plurality of candidate lines, which have different angles formed with respect to a reference direction, can be determined for the object to be processed, and in the third step, an inclination direction can be identified in which the crack of each of the plurality of candidate lines is inclined with respect to a corresponding candidate line, and the reference line can be determined for the object to be processed on the basis of a first candidate line, the inclination direction of which of the crack is on one side of a corresponding candidate line and which has a smallest or largest angle formed with respect to the reference direction, and a second candidate line,whose crack inclination direction is located on another side of a corresponding candidate line and which has a smallest or largest angle formed with respect to the reference direction, are determined from the majority of candidate lines.

[0024] It has been established that the angle between the angle formed by the first candidate line with respect to the reference direction and the angle formed by the second candidate line with respect to the reference direction corresponds to the crystal orientation of the substrate. Therefore, by defining the reference line, which is the line indicating the crystal orientation of the substrate, the reference line can be determined with high accuracy based on the first and second candidate lines. In this case, the method can also be applied to a case where the crack does not exhibit a regularly repeated deflection pattern. Advantageous effects of the invention

[0025] In one aspect of the present invention, it is possible to provide a laser processing device and a laser processing method that are able to prevent the cutting line from deviating and being fixed with respect to the crystal orientation of the substrate of the object to be processed. Brief description of the drawings Fig. Figure 1 is a schematic graphic representation of a laser processing device used to form a modified area. Fig. Figure 2 is a top view of an object to be processed, for which the modified area is formed. Fig. 3 is a cross-sectional view of the object to be edited along line III-III of Fig. 2. Fig. Figure 4 is a top view of the object being processed after laser processing. Fig. 5 is a cross-sectional view of the object to be edited along line VV of Fig. 4. Fig. 6 is a cross-sectional view of the object to be edited along line VI-VI of Fig. 4. Fig. Figure 7 is a cross-sectional view of the object to be processed to illustrate laser processing along a candidate line. Fig. 8(a) is a top view illustrating a first example of a front surface of a substrate on which a half section is formed. Fig. Figure 8(b) is a top view illustrating a second example of the front surface of the substrate on which the half-section is formed. Fig. 9(a) is a diagram illustrating an example of a relationship between a crop period and an angle formed by a candidate line with respect to a crystal orientation. Fig. 9(b) is a diagram illustrating an example of a relationship between the length of the half-section and the frequency of occurrence of a cranked shape. Fig. 10(a) is a top view illustrating a third example of the front surface of the substrate on which the half-section is formed. Fig. 10(b) is a top view illustrating a fourth example of the front surface of the substrate on which the half-section is formed. Fig. 11(a) is a photographic view that shows an enlarged view of the front surface of the substrate on which the half-section is formed. Fig. 11(b) is a further top view illustrating the enlarged front surface of the substrate on which the half-section is formed. Fig. Figure 12 is a schematic graphic representation illustrating a laser processing device according to a first embodiment. Fig. Figure 13 is a flowchart illustrating a laser processing procedure according to the first embodiment. Fig. Figure 14 is a flowchart illustrating the processing of a setting of a reference line in the laser processing method according to the first embodiment. Fig. Figure 15(a) is a top view illustrating an example of the candidate line and the reference line obtained by processing Fig. 14 have been determined. Fig. 15(b) is a diagram to explain the reference line in the processing of Fig. 14. Fig. Figure 16 is a top view illustrating an example of the front surface of the substrate on which marking is carried out. Fig. Figure 17 is a top view that enlarges and illustrates an example of the cutting line defined in a section. Fig. Figure 18 is a flowchart illustrating the processing of a setting of the reference line in a laser processing method according to a first embodiment. Fig. Figure 19(a) is a top view illustrating an example of the candidate line and the reference line obtained by processing Fig. 18 have been determined. Fig. 19(b) is a diagram to explain the reference line in the processing of Fig. 18. Fig. Figure 20 is a flowchart illustrating the processing of a setting of the reference line in a laser processing method according to a third embodiment. Fig. 21(a) is a diagram illustrating an example of a processing result of the laser processing method according to the third embodiment. Fig. 21(b) is a diagram illustrating a further example of the processing result of the laser processing method according to the third embodiment. Description of embodiments

[0026] In the following, embodiments of the present invention are explained in detail with reference to the drawings. In the drawings, the same or equivalent parts are identified by the same reference numerals without superfluous description.

[0027] Laser processing devices and laser processing methods according to the embodiments converge the laser light onto the object to be processed, thereby forming a modified area on the object along a processing line (which includes a candidate line, a reference line, and a cutting line). Therefore, the formation of the modified area is first performed with reference to Fig. 1 to 6 described.

[0028] As in Fig. As illustrated in Figure 1, a laser processing device 100 comprises a laser light source 101 to cause a laser light L to pulsate and oscillate, a dichroic mirror 103 arranged to change the direction of the optical axis (optical path) of the laser light L by 90°, and a converging lens 105 for converging the laser light L. The laser processing device 100 further comprises a support table 107 for holding an object 1 to be processed, which is illuminated with the laser light L converged by the converging lens 105, a table 111 for moving the support table 107, a laser light source control unit 102 for adjusting the laser light source 101 to adapt the output, pulse width, pulse waveform, and the like of the laser light L, and a table control unit 115 for adjusting the movement of the table. 111.

[0029] In the laser processing device 100, the laser light L emitted by the laser light source 101 changes the direction of its optical axis by 90° using the dichroic mirror 103 and is then converged through the converging lens 105 into the interior of the object 1 to be processed, which is mounted on the support table 107. Simultaneously, the table 111 is moved such that the object 1 to be processed moves along a processing line 5 relative to the laser light L. Accordingly, the modified area along the processing line 5 is formed in the object 1 to be processed. While the table 111 is moved to move the laser light L relative to it, the converging lens 105 can be moved either instead or in conjunction with it.

[0030] The object to be processed is a planar element (e.g., a substrate or a wafer), examples of which include semiconductor substrates made of semiconductor materials and piezoelectric substrates made of piezoelectric materials. As in Fig. As illustrated in Figure 2, the cutting line for cutting the object 1 to be processed is defined as processing line 5 for the object 1 to be processed. Processing line 5 is a straight, virtual line. In a case where the modified area is formed inside the object 1 to be processed, the laser light L is directed relatively along processing line 5 (that is, in the direction of an arrow A in Figure 2). Fig. 2) moves while a convergence point (a convergence position) P is located inside the object 1 being processed, as in Fig. 3 illustrates this. Accordingly, as in Fig. 4, Fig. 5 and Fig. Figure 6 illustrates a modified area 7 formed in the object 1 to be machined along the machining line 5. In a case where the machining line 5 is the cutting line, the modified area 7 formed along the machining line 5 is a cutting start point area 8.

[0031] A convergence point P is a position to which the laser light L converges. The processing line 5 can be curved instead of straight, can be three-dimensional, combining these features, or can be specified by coordinates. The processing line 5 can be actually drawn on a front surface 3 of the object 1 to be processed, without being limited to the virtual line. The modified area 7 can be continuous or discontinuous. The modified area 7 can be formed in rows or points and simply needs to be located at least within the interior of the object 1 to be processed.The crack can be formed from the modified area 7 as the starting point, and the crack and the modified area 7 can be exposed on an outer surface (the front surface 3, a rear surface 21, or an outer circumferential surface) of the object 1 to be processed. A laser light entry point during the formation of the modified area 7 is not limited to the front surface 3 of the object 1 to be processed, but can be the rear surface 21 of the object 1 to be processed.

[0032] Furthermore, in a case where the modified region 7 is formed inside the object 1 being processed, the laser light L is transmitted through the object 1 and is absorbed particularly near the convergence point P, which is located inside the object 1. Accordingly, the modified region 7 is formed within the object 1 being processed (i.e., laser processing with internal absorption). In this case, the front surface 3 of the object 1 being processed hardly absorbs the laser light L and consequently does not melt.In a case where the modified area 7 is formed on the front surface 3 of the object 1 to be processed, the laser light L is absorbed particularly near the convergence point P, which is located on the front surface 3, and distance sections such as holes and grooves are formed (laser processing with surface absorption) by being melted and removed from the front surface 3.

[0033] Modified region 7 is a region where density, refractive index, mechanical strength, and other physical properties differ from the surroundings. Examples of modified region 7 include molten, machined regions (meaning regions that have resolidified after being melted, those in the molten state, and / or those in the process of resolidifying from the molten state), cracked regions, regions of dielectric breakdown, regions of altered refractive index, and their mixed regions.Other examples of the modified region 7 include regions where the density of the modified region 7 has changed compared to that of an unmodified region, and regions that are formed with a lattice defect in a material of the object 1 to be processed (which can also be referred to collectively as regions with high dislocation density).

[0034] The molten, machined areas, the areas with a modified refractive index, the areas where the modified area 7 has a different density than that of the unmodified area, and areas containing a lattice defect may further contain a crack (cut or microcrack) within it or at an interface between the modified area 7 and the unmodified area. The crack may extend over the entire surface of the modified area 7, or only in a portion or multiple portions thereof. The object 1 to be machined comprises a substrate made of a crystalline material with a crystal structure. For example, the object 1 to be machined comprises a substrate made of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO3, and / or sapphire (Al2O3).In other words, the object to be processed, 1, contains, for example, a gallium nitride substrate, a silicon substrate, a SiC substrate, a LiTaO3 substrate, or a sapphire substrate. The crystalline material can be either an anisotropic or an isotropic crystal.

[0035] In this embodiment, the modified area 7 can be formed by creating a plurality of modified locations (machining marks) along the machining line 5. In this case, the plurality of modified locations together constitute the modified area 7. The modified location is a modified section formed by a pulse of pulsed laser light L (that is, a laser irradiation pulse; a laser shot). Examples of modified locations include cracks, molten areas, machined areas, areas with a changed refractive index, and those in which at least one of these is mixed.Regarding the modified areas, their size and the lengths of any cracks originating from them can be controlled as needed, taking into account the required cutting accuracy, the required flatness of cut surfaces, the thickness, type, and crystal orientation of the object 1 to be machined, and the like. Furthermore, in the present embodiment, the modified area can be configured as a modified region 7 along the machining line 5.

[0036] In this embodiment, the modified region 7 is formed along the candidate line inside the object 1 to be processed, and a crack (hereinafter referred to as a "half-section") extending from the modified region 7 to the front face 3 or the rear face 21 is formed along the candidate line. Based on the state of the half-section, the crystal orientation of the object 1 to be processed is identified, and the reference line is established, which is a line indicating the crystal orientation. A principle for identifying the crystal orientation of the object 1 to be processed and for establishing the reference line is described below.

[0037] As in Fig. As illustrated in Figure 7, a candidate line 5A is defined for the object 1 to be processed, which contains a substrate 12 made of the crystalline material. The convergence point P is aligned with the interior of the object 1, and the laser light L is emitted along the candidate line 5A onto a front surface 12a of the substrate 12, which serves as the laser light entry surface. Accordingly, one or more rows (two rows in the illustrated example) of modified regions 7 are formed in the interior of the substrate 12 in the thickness direction along the candidate line 5A. Simultaneously, the half-section, which is a surface crack extending from the modified region 7 to the front surface 12a, is generated along the candidate line 5A.Furthermore, the illustrated direction Z is a direction that corresponds to the thickness direction of the object 1 to be processed, the direction X is a direction perpendicular to the direction Z, and the direction Y is a direction orthogonal to both the direction Z and the direction Y (the same applies below).

[0038] Fig. 8(a) and Fig. Figure 8(b) are diagrams, each illustrating an example of a half-section Hc as seen from the front surface 12a. The example of Fig. Figure 8(b) illustrates a case in which an angular deviation Δθ, which is an angle in which a direction of extension of the candidate line 5A deviates with respect to a direction of a crystal orientation K of the substrate 12, is greater than the angle of the example of Fig. 8(a). For example, in a case where the substrate 12 is a SiC substrate, the crystal orientation K is the crystal orientation K of its m-plane.

[0039] As in Fig. 8(a) and Fig. As illustrated in Figure 8(b), the half-section Hc is formed by regularly repeated shapes, each extending circumferentially in a deflection direction that intersects the extension direction of candidate line 5A as seen from the front surface 12a. The half-section Hc has a shape in which a cranked shape, which is a deflection shape, that is, a sawtooth shape, extends so that it is inclined with respect to candidate line 5A and then bends in a direction that intersects candidate line 5A, is regularly repeated.

[0040] It has been found that in a case where the angular deviation Δθ is large, the degree of deflection of the half-section Hc is smaller than in a case where the angular deviation Δθ is small. The degree of deflection is an index value representing the extent of the deflection. The degree of deflection includes, for example, a period of deflection, a frequency of deflection, and a magnitude of deflection. Specifically, the degree of deflection includes a deflection period (a period of deflection), which is a length (span) in one direction along candidate line 5A in a deflected shape, and a frequency of occurrence (a frequency of deflection) of the deflected shape for a given length of half-section Hc.

[0041] In a case where the angular deviation Δθ is large, the cropping period is smaller and the frequency of occurrence of the cropped form is higher for a given length of the half-section Hc than in a case where the angular deviation Δθ is small. Accordingly, it is found that there is a certain correlation between the magnitude of the angular deviation Δθ and the half-section Hc. In particular, it is found that the smaller the angular deviation Δθ (the closer the direction of extension of the candidate line 5A is to the crystal orientation K), the larger the cropping period and the lower the frequency of occurrence of the cropped form.

[0042] Fig. Figure 9(a) is a diagram illustrating an example of a relationship between an angle formed by the candidate line 5A with respect to the crystal orientation K and the crop period, which is the degree of deflection of the half-section Hc. Fig. Figure 9(b) is a diagram illustrating an example of a relationship between a coordinate of candidate line 5A and the occurrence frequency of the offset shape, which is the degree of deflection of the half-section Hc. A distance between coordinates corresponding to a difference between the occurrence frequencies of the offset shape corresponds to the length between the offsets, that is, the offset period. In the figure, the angle formed by candidate line 5A with respect to the crystal orientation K (hereafter referred to simply as the "angle of candidate line 5A") is the angle when an angle of a standard machining line, determined as the default setting, is 0°. The standard machining line is, for example, a line parallel to an orientation surface of the object 1 to be machined.The cropping period here is an average of a given number of cropping periods. The cropping period is presented as a relative value based on a specific cropping period as a reference.

[0043] As in Fig. As illustrated in Figure 9(a), the cropping period changes by changing the angle of the candidate line 5A. Accordingly, given the above observation that the angular deviation Δθ decreases as the cropping period increases and the direction of the machining line 5 approaches the direction of the crystal orientation K, it becomes apparent that the crystal orientation K can be obtained from the candidate line 5A, which has a large cropping period. In the illustrated example, the angle of the candidate line 5A and the cropping period are inversely proportional to each other. An optimal angle of the candidate line 5A is -0.05°, and in this case, a direction rotated by -0.05° relative to a direction of the standard machining line can be identified as the crystal orientation K, and the candidate line 5A rotated by -0.05° relative to the standard machining line can be designated as the reference line 5B.

[0044] As in Fig. Figure 9(b) illustrates that, the higher the angular deviation Δθ, the higher the frequency of occurrence of the bent form for a given length of the half-section Hc (the shorter the bent period). Accordingly, it becomes apparent that the crystal orientation K can be obtained from candidate line 5A, which exhibits a low frequency of occurrence of the bent form.

[0045] Fig. 10(a) and Fig. Figure 10(b) shows views that each illustrate a further example of the half-section Hc as seen from the front surface 12a. In the example of Fig. 10(a) and the example of Fig. 10(b) directions of the angular deviation Δθ differ with respect to the candidate line 5A. In a case where it is divided into one side and the other side by the candidate line 5A, if the cranked shape of the half-section Hc has a shape extending such that it is inclined to one side of the candidate line 5A, as in Fig. Figure 10(a) illustrates the direction of the crystal orientation K inclined to one side with respect to candidate line 5A. If the cranked shape of the half-section Hc has a shape extending such that it is inclined to the other side of candidate line 5A, as in Fig. As illustrated in Figure 10(b), the direction of the crystal orientation K is inclined to the other side with respect to the candidate line 5A.

[0046] Fig. 11(a) and Fig. Figure 11(b) shows photographic views, each illustrating an enlarged example of the half-section Hc as seen from the front surface 12a. In the example shown in the figure, the substrate 12 is a SiC substrate, and a section 17 described below is illustrated. The candidate line 5A is defined on the section 17 parallel to a direction of extension of the section 17. The Fig. The illustrated half-section Hc in Figure 11(a) has a shape in which the cranked form extends upwards with respect to candidate line 5A. In this case, the direction of the crystal orientation K exhibits an angular deviation Δθ counterclockwise with respect to candidate line 5A from the front face 12a. The Fig. 11(b) The illustrated half-section Hc has a shape in which the cranked form extends downwards with respect to candidate line 5A. In this case, the direction of the crystal orientation K exhibits an angular deviation Δθ clockwise with respect to candidate line 5A from the front face 12a.

[0047] As described above, in this embodiment, a direction of candidate line 5A can be identified as the crystal orientation K in which the candidate line exhibiting the least degree of deflection of the half-section Hc (for example, the largest bending period or the lowest frequency of occurrence of the bent shape) can be identified among a plurality of candidate lines 5A. The candidate line 5A can be defined as the reference line 5B, which specifies the direction of the crystal orientation K.

[0048] A search is conducted for candidate line 5A where the degree of deflection of the half-section Hc falls within a predefined range (where, for example, the offset period is equal to or greater than a threshold value, or the frequency of occurrence of the offset shape is equal to or less than a certain value). The direction of the found candidate line 5A can be identified as the crystal orientation K. Candidate line 5A can be defined as the reference line 5B. The direction of an angle of the crystal orientation K with respect to candidate line 5A can be identified from the direction of deflection of the half-section Hc (a tilt direction of the offset shape with respect to candidate line 5A).In other words, based on whether the half-section Hc extends upwards or downwards with respect to candidate line 5A, it can be determined whether the angular deviation Δθ of the crystal orientation K with respect to candidate line 5A is in the positive or negative direction.

[0049] Next, a laser processing device of a first embodiment is described with reference to the schematic graphic representation of Fig. 12 described.

[0050] A laser processing device 300 converges the laser light L onto the object 1 to be processed such that the modified area 7 in the object 1 is formed along the processing line 5 (which includes the candidate line 5A, the reference line 5B, and the cutting line 5C). Furthermore, the laser processing device 300 converges the laser light L onto the front surface 12A of the substrate 12 in the object 1 to form markings M, which are a plurality of indentation marks along the processing line 5 (see Fig. 16) The majority of markings M along the processing line 5 are arranged side by side along the processing line 5 at intervals corresponding, for example, to a pulse interval (relative speed of the pulsed laser light to the object being processed 1 / repetition period of the pulsed laser light). The majority of markings M constitute a reference mark indicating the crystal orientation K. Here, the markings M are formed by a modified area (a modified region 7) designed to be exposed on the front surface 12a.

[0051] The laser processing device 300 comprises a laser light source 202, a converging optical system 204, and an area observation unit (imaging unit) 211. The laser light source 202, the converging optical system 204, and the area observation unit 211 are provided in a housing 231. The laser light source 202 emits laser light L, which has a wavelength that is transmitted through the object 1 to be processed. The wavelength is, for example, 532 nm to 1,500 nm. The laser light source 202 is, for example, a fiber laser or a solid-state laser. The converging optical system 204 converges the laser light L emitted by the laser light source 202 into the interior of the object 1 to be processed. The converging optical system 204 comprises a plurality of lenses.The converging optical system 204 is mounted on a base plate 233 of the housing 231 above a control unit 232 which includes a piezoelectric device and the like.

[0052] In the laser processing device 300, the laser light L, which is emitted by the laser light source 202, is transmitted successively through the dichroic mirrors 210 and 238 in such a way that it enters the converging optical system 204 and is converged by the converging optical system 204 into the object 1 to be processed, which is mounted on the support table 107 on the table 111.

[0053] The area observation unit 211 observes the laser light entrance surface of the object 1 to be processed. The area observation unit 211 images the front surface 12a of the substrate 12 in the object 1 to be processed, which is supported by the support table 107. The area observation unit 211 includes an observation light source 211a and a detector 211b. The observation light source 211a emits visible light VL1. The observation light source 211a is not subject to any special restrictions, and a known light source can be used.

[0054] The detector 211b detects reflected light VL2 of the visible light VL1, which is reflected by the laser light entrance surface of the object 1 to be processed, in order to capture an image of the front surface 12a (hereinafter simply referred to as the "surface image"). The detector 211b captures a surface image that includes the half-section Hc. In addition, the detector 211b captures a surface image that includes the plurality of markings M. The detector 211b is not subject to any particular limitations, and a known imaging device such as a camera can be used.

[0055] In the area observation unit 211, the visible light VL1, emitted by the observation light source 211a, is reflected or transmitted by a mirror 208 and dichroic mirrors 209, 210, and 238 such that it converges through the converging optical system 204 onto the object 1 to be processed. The reflected light VL2, reflected by the laser light entrance surface of the object 1 to be processed, is converged by the converging optical system 204 such that it is transmitted or reflected by the dichroic mirrors 238 and 210, and is subsequently transmitted through the dichroic mirror 209 such that it is received by the detector 211b.

[0056] The laser processing device 300 includes a display unit 240 for displaying the surface image acquired by the surface observation unit 211, and a control unit 250 for controlling the laser processing device 300. A screen or the like can be used as the display unit 240.

[0057] The control unit 250 includes, for example, a CPU, a ROM, a RAM, and the like. The control unit 250 controls the laser light source 202 such that the output, pulse width, and other parameters of the laser light L emitted by the laser light source 202 are adjusted. When forming the modified area 7, the control unit 250 controls the housing 231, a position of the table 111 (the support table 107), and / or activates the control unit 232 to position the convergence point P of the laser light L on the front surface 3 (the front surface 12a) of the object 1 to be processed, or at a position within the specified distance from the front surface 3 (or the rear surface 21). When forming the modified area 7, the control unit 250 controls the housing 231, the position of the table 111 and / or the control of the control unit 232 so that the convergence point P is moved relatively along the machining line 5.

[0058] The control unit 250 defines the plurality of candidate lines 5A, extending in different directions, for the object 1 to be processed. The control unit 250 controls the operation of the table 111 (the support table 107), the laser light source 202 and / or the control unit 232 (the converging optical system 204) such that the modified area 7 is formed inside the substrate 12 and the half-section Hc is formed along each of the plurality of candidate lines 5A.

[0059] The control unit 250 controls the operation of the surface observation unit 211 for imaging the surface image. The control unit 250 determines the reference line 5B based on the surface image acquired by the surface observation unit 211 and sets the reference line 5B for the object 1 to be processed. Specifically, image recognition processing is performed on a plurality of the surface images containing the half-section Hc, and the candidate line 5A from a predefined number of candidate lines 5A, which exhibits the smallest degree of deflection of the half-section Hc, is set as the reference line 5B for the object 1 to be processed. This reference line indicates the crystal orientation K of the substrate 12. Here, the cropping period of each of the plurality of half-sections Hc from the surface images is recognized, and the candidate line 5A corresponding to the half-section Hc exhibiting the largest cropping period is set as the reference line 5B.The image recognition processing performed by the control unit 250 is not subject to any special restrictions, and a generally known image recognition processing method such as pattern recognition or the like can be selected.

[0060] The control unit 250 controls the operation of the table 111, the laser light source 202 and / or the control unit 232 such that the majority of markings M (see Fig. 16) is formed on the object 1 to be processed along the reference line 5B.

[0061] The control unit 250 performs image recognition processing on the surface image containing the majority of markings M and detects the orientation of the markings M. Based on the orientation of the detected markings M, the control unit 250 identifies the crystal orientation K and aligns the cutting line 5C. For example, the control unit 250 sets the cutting line 5C or modifies the existing cutting line 5C so that the cutting line 5C is parallel to the orientation of the markings M (parallel to the crystal orientation K).

[0062] The control unit 250 defines the cutting line 5C, which runs through the section 17 of the object 1 to be processed, as described below. In a case where the direction of extension of the section 17 does not coincide with the crystal orientation K, the control unit 250 defines the cutting line 5C for the object 1 to be processed as parallel to the crystal orientation K and inclined with respect to the direction of extension of the section 17.

[0063] Next, a laser processing procedure, which is carried out in the laser processing device 300, will be described with reference to the flowcharts of Fig. 13 and Fig. 14 described.

[0064] The laser processing method of the present embodiment is used, for example, in a manufacturing process for producing a semiconductor chip such as a light-emitting diode. In a method according to the present embodiment for cutting an object to be processed, the object 1 to be processed is first prepared. As in Fig. As illustrated in Figure 15(a), the object 1 to be processed is a blank wafer and includes the substrate 12. An orientation surface OF is provided on the substrate 12. The substrate 12 includes an ineffective area 16x, which is provided at an outer edge section on the front surface 12a, and an effective area 16y, which is provided within the ineffective area 16x. The effective area 16y is a region in which a functional device layer 15, described below, is provided. The ineffective area 16y is a region in which the functional device layer 15 is not provided.

[0065] The reference line 5B for the object 1 to be machined is then defined (S10). Specifically, the substrate 12 is first placed on the support table 107 of the table 111. The control unit 250 defines the candidate line 5A parallel to the orientation surface OF (or inclined at a reference angle in the direction θ) as the standard machining line (S11). The control unit 250 changes the angle of the candidate line 5A in the direction θ such that the angle of the candidate line 5A deviates from the standard machining line by a specified angle in the direction θ (S12). The direction θ is a direction of rotation with the direction Z as the axial direction. The reference angle and the specified angle are predetermined angles that are not subject to any special restrictions and can be derived, for example, from the specification or the condition of the substrate 12.

[0066] The laser light L is then scanned once or several times along the candidate line 5A in the ineffective region 16x as it converges into the interior of the substrate 12, and one or more rows of the modified region 7 are formed inside the substrate 12 in the ineffective region 16x. Accordingly, the half-section Hc, which reaches the front surface 12a of the substrate 12 in the ineffective region 16x, is formed along the candidate line 5A (S13). During multiple scans of the laser light L, a scan of the laser light L in the same direction (a so-called setup operation) is repeated several times. Subsequently, the surface image, which includes the half-section Hc, is imaged by the surface observation unit 211 and stored in a memory unit (ROM or RAM) of the control unit 250.When scanning the laser light L multiple times, the laser light L can be scanned back and forth along the candidate line 5A (a so-called back-and-forth processing).

[0067] The laser processing according to S12 and S13 is then repeated until the processing frequency reaches a predetermined, predefined frequency (here five times) (S14). In S12, which is repeated several times, the angle is changed so that the angle of the candidate line 5A in the direction θ is not identical, and as a result, the predetermined number of candidate lines 5A extending in different predetermined directions is determined.

[0068] The control unit 250 then performs image recognition processing on the plurality of stored surface images and identifies and evaluates a state of each of the plurality of half-sections Hc (S15). The control unit 250 selects the half-section Hc with the largest crop period from a plurality of the identified crop periods. The control unit 250 selects the candidate line 5A from the plurality of candidate lines 5A where the candidate line 5A runs along the half-section Hc with the largest crop period (S16). The control unit 250 then defines the selected candidate line 5A as the reference line 5B, which specifies the crystal orientation K of the substrate 12, for the object 1 to be processed (S17). One direction (one crystal orientation K) of the defined reference line 5B is stored in the memory unit of the control unit 250.

[0069] For example, in S16, as in Fig. Figure 15(b) illustrates that a candidate line 5G with the largest crop period is selected from the five candidate lines 5A defined in the ineffective region 16x. In this case, a direction of the candidate line 5G is determined as the crystal orientation K in S17, and the reference line 5B parallel to the candidate line 5G is defined in the ineffective region 16x. The direction of the reference line 5B can be represented as an angle (optimal angle) in the direction θ from a parallel direction of the orientation surface OF. The reference line 5B is a line that extends such that it deviates in the direction θ from the parallel direction of the orientation surface OF in the ineffective region 16x by the optimal angle.

[0070] Subsequently, the majority of markings M, arranged along the reference line 5B, are marked on the front surface 12a of the substrate 12 (S20). In 20, the laser light L is scanned as it converges onto the front surface 12a of the substrate 12 along the reference line 5B in the ineffective region 16x, and the majority of markings M are formed along the reference line 5B on the front surface 12a of the substrate 12 in the ineffective region 16x (see Fig. 16).

[0071] The substrate 12 is then removed from the table 111, and the functional device layer 15 is formed on the front surface 12a of the substrate 12 (S30). The functional device layer 15 comprises a plurality of functional devices 15a (for example, a light-receiving device such as a photodiode, a light-emitting device such as a laser diode, or a device configured as a circuit) arranged in a matrix in the effective area 16y of the front surface 12a. The sectioning area (the sectioning area) 17 is formed between the adjacent functional devices 15a.

[0072] In S30, the functional device layer 15 is formed using the orientation surface OF as a reference. Specifically, the majority of functional devices 15a, arranged in the parallel and a vertical direction of the orientation surface OF, are arranged in the effective area 16y of the front surface 12a. The grid-like section 17, extending in the parallel and vertical direction of the orientation surface OF, is formed between the majority of functional devices 15a.

[0073] A tension band is then attached to the rear surface 21 of the object 1 to be processed, which includes the substrate 12 and the functional device layer 15, and the object 1 to be processed is mounted on the table 111. The surface image, which includes the plurality of markings M, is imaged by the surface observation unit 211. The control unit 250 recognizes the orientation of the plurality of markings M from the surface image. The control unit 250 identifies the orientation of the plurality of markings M as the crystal orientation K. The control unit 250 sets the cutting line 5C parallel to the orientation of the markings M and extending through the section 17, and the cutting line 5C orthogonal to the orientation of the markings M and extending through the section 17 (S40).In other words, the lattice-like cutting line 5C, which passes through the section 17 between the majority of functional devices 15a, is determined by adjusting the angle in the direction θ such that it extends along the parallel direction and an orthogonal direction of the identified crystal orientation K.

[0074] Fig. Figure 17 is a top view illustrating the functional device layer 15 in greater detail. As in Fig. As illustrated in Figure 17, for example, in S40 the cutting line 5C is defined such that it passes through the section 17 of the object 1 to be machined. Furthermore, the cutting line 5C in the section 17 is defined such that it runs along the parallel and orthogonal directions of the crystal orientation K. In the illustrated example, the extension direction of the section 17 (the direction in which the functional devices 15a are arranged) does not coincide with the crystal orientation K. In this case, in S40 the cutting line 5C passing through the section 17 is defined such that it is inclined with respect to the extension direction of the section 17 and, viewed from direction Z, is parallel to the crystal orientation K.Furthermore, the cutting line 5C, which passes through the section region 17, is defined such that it is inclined with respect to the extension direction of the section region 17 and, viewed from the direction Z, is perpendicular to the crystal orientation K.

[0075] The object 1 to be processed is then cut along the cutting line 5C such that a plurality of semiconductor chips (for example, a memory, an IC, a light-emitting device, and a light-receiving device) are formed (S50). Specifically, the laser light L is scanned once or several times along the cutting line 5C as it converges into the interior of the object 1. Accordingly, one or more rows of the modified region 7 are formed inside the object 1 along the cutting line 5C. Subsequently, the object 1 is cut by stretching the stretching band along the cutting line 5C from the modified region 7 as the starting point of the cutting, such that it is separated from each other as a plurality of semiconductor chips.

[0076] Furthermore, it has been observed that the number of height differences on the cut surface of the object 1 to be machined, which is cut along the machining line 5, increases with the increasing degree of deflection of the half-section Hc, which occurs in a case where the modified area 7 is formed along the machining line 5. In light of this observation, in the present embodiment, the reference line 5B for the object 1 to be machined is determined based on the surface image, which includes the half-section Hc along each of the plurality of candidate lines 5A extending in different directions.

[0077] Accordingly, it is possible to define the cutting line 5C, which extends in a direction parallel to the reference line 5B. Consequently, it is possible to prevent the cutting line 5C from deviating with respect to the crystal orientation K of the substrate 12 and to fix it in place. It is also possible to prevent the height difference in the cut surface (end face) of the chip, which is obtained by cutting the object 1 to be processed, and to smooth the cut surface of the chip, ultimately producing a mirror surface. Furthermore, the yield of the chip can be improved.

[0078] Furthermore, the directions of the orientation surface OF and the crystal orientation K can generally deviate from each other by a maximum of approximately 1°. Therefore, compared to a case where the cutting line 5C is fixed parallel to the orientation surface OF, the present embodiment, which exhibits the effect described above, is particularly effective.

[0079] In the present embodiment, the control unit 250 defines the predetermined number of candidate lines 5A extending in different predetermined directions and selects the candidate line 5A exhibiting the smallest degree of deflection of the half-section Hc from this predetermined number of candidate lines 5A as the reference line 5B. Accordingly, it is sufficient to perform laser light irradiation L, confirmation of the state of the half-section Hc, and the like only for the predetermined number of candidate lines 5A, thus enabling the straightforward determination of the reference line 5B.

[0080] In the present embodiment, the control unit 250 defines the predetermined number of candidate lines 5A for the substrate 12, which extend in different predetermined directions, using the orientation surface OF with which the object 1 to be machined is equipped as a reference. That is, the standard machining line parallel to the orientation surface OF is defined, and the predetermined number of candidate lines 5A is defined using the standard machining line as a reference. Accordingly, variations in the definition of the candidate lines 5A for each object 1 to be machined can be prevented.This is particularly effective in cases where a high degree of agreement is required between the direction of the orientation surface OF and the direction of the crystal orientation K, since determining the majority of candidate lines 5A can only be achieved through fine-tuning from the standard processing line. This is also effective in cases where the chips are mass-produced from the object 1 being processed.

[0081] The present embodiment includes a display unit 260 that shows the surface image captured by the surface observation unit 211. Accordingly, an operator can confirm the status of the half-section Hc and the like.

[0082] In the present embodiment, the plurality of markings M are formed on the object 1 to be machined along the reference line 5B. Accordingly, it is possible to define the cutting line 5C for the object 1 to be machined using the plurality of markings M as a reference, which extends in the direction parallel to the reference line 5B.

[0083] In the present embodiment, the cutting line 5C, which extends in the direction parallel to the reference line 5B, is defined for the object 1 to be processed, and the modified area 7 is formed inside the substrate 12 along the cutting line 5C. Accordingly, a series of steps, such as irradiation with laser light L along the candidate line 5A, confirmation of the state of the half-cut Hc, definition of the reference line 5B, definition of the cutting line 5C, and irradiation with laser light L along the cutting line 5C, can be performed in a laser processing device 300.

[0084] In the present embodiment, the candidate line 5A and the reference line 5B are defined in the ineffective area 16x of the substrate 12, and the majority of markings M are formed on the front surface 12a in the ineffective area 16x of the substrate 12. Accordingly, when manufacturing the chip by cutting the object 1 to be processed, it is possible to effectively utilize a section (an ineffective area 16x) that is normally removed and discarded. The candidate line 5A and the reference line 5B can be defined in the ineffective area 16x. The majority of markings M can be formed in the effective area 16y.

[0085] In the present embodiment, when forming the plurality of rows of modified areas 7 along the candidate line 5A to form the half-section Hc, the laser light L is not scanned back and forth along the candidate line 5A, but rather the laser light L is repeatedly scanned several times in the same direction. Accordingly, the half-section Hc can reach the front surface 12a from the modified area 7 in a suitable manner, and a deflection of the half-section Hc (a bent shape) can be clearly observed.

[0086] The present embodiment is not limited to the above and can be designed as follows.

[0087] In the present embodiment, the plurality of markings M arranged along the reference line 5B are formed as reference marks; however, the reference mark to be formed is not subject to any particular restriction. For example, a new orientation surface (a plane formed on a portion of the outer circumferential surface of the substrate 12), which differs from the orientation surface OF, can be provided parallel to the reference line 5B as a reference mark. A surface cut using the half-section Hc of the optimal candidate line 5A can be used as a new orientation surface and reference mark. The modified area 7 can be formed in the object 1 to be processed along the reference line 5B by irradiation with laser light L, and the surface cut from the modified area 7 as the starting point can be used as a new orientation surface and reference mark.Furthermore, various well-known processing methods can be chosen to create the new orientation surface.

[0088] The reference mark can be a crack extending from the modified area 7 in the substrate 12 to the front surface 12a. The reference mark can be formed by a shape (including a two-dimensional shape and a three-dimensional shape) indicating a crystal orientation, a pattern, a color, an indication, a one-dimensional code, a two-dimensional code, or the like, or by a combination thereof. The reference mark can be a scribed line formed along the reference line 5B.

[0089] In the present embodiment, the control unit 250 performs image recognition processing on the surface image of the substrate 12 to automatically detect the degree of deflection of the half-section Hc; however, the degree of deflection of the half-section Hc can also be detected from the surface image displayed on the display unit 240 or visually by the operator. In this case, the operator can, for example, perform an operation in an operating unit connected to the control unit 250 to define the reference line 5B based on the degree of deflection of the half-section Hc in order to define the reference line 5B for the object 1 to be processed.

[0090] In the present embodiment, the control unit 250 performs image recognition processing on the surface image of the substrate 12 to automatically detect the plurality of markings M; however, the plurality of markings M can also be detected from the surface image displayed on the display unit 240 or visually by the operator. In this case, the operator can, for example, perform an operation in the control unit connected to the control unit 250 to define the cutting line 5C parallel to the arrangement direction of the plurality of markings M in order to define the cutting line 5C for the object 1 to be processed.

[0091] In the present embodiment, in S30, where the functional device layer 15 is formed on the front surface 12a of the substrate 12, the functional device layer 15 is formed using the orientation surface OF as a reference; however, the functional device layer 15 can also be formed using the plurality of markings M as a reference. In particular, the plurality of functional devices 15a, which are arranged in the arrangement direction and in their vertical direction of the plurality of markings M, can be arranged in the effective area 16y of the front surface 12a, and the grid-like section 17, which extends in the arrangement direction and in its vertical direction of the plurality of markings M, can be formed between the plurality of functional devices 15a.Accordingly, the majority of functional devices 15a and the track section 17 can be arranged exactly along the crystal orientation K.

[0092] In the present embodiment, after step S20, in which marking is performed on the substrate 12, step S30 is performed, in which the functional device layer 15 is created; however, without being limited to this, the object 1 to be processed can be used in which the functional device 15a is pre-formed on the substrate 12 (a so-called wafer with a pre-formed device). That is, after step S10, in which the reference line 5B for the object 1 to be processed is defined, on which the functional device 15a is pre-formed on the substrate 12, step S20, in which marking is performed, is carried out, and step S40, in which the cutting line is defined, can be carried out immediately. In this case, the cutting line 5C can be defined in step S40 so that it runs parallel to the defined reference line 5B, without carrying out step S20, in which marking is carried out.

[0093] Next, a second embodiment is described. The description of the second embodiment details aspects that differ from the first embodiment.

[0094] In the present embodiment, the control unit 250, based on the surface image generated by the surface observation unit 211, successively defines the plurality of candidate lines 5A for the object 1 to be processed until the degree of deflection of the half-section Hc falls within the specified range. The control unit 250 then defines the candidate line 5A for which the degree of deflection of the half-section Hc falls within the specified range as the reference line 5B for the object 1 to be processed. Here, candidate line 5A is defined as reference line 5B, with candidate line 5A running along the half-section Hc that has a deflection period equal to or greater than the threshold value.

[0095] As in Fig. As illustrated in Figure 18, the reference line 5B in the laser processing method according to the second embodiment in S10 is defined as follows. That is, first the substrate 12 is placed on the support table 107 of the table 111. The candidate line 5A parallel to the orientation surface OF (or inclined at a reference angle in the direction θ) is defined as the standard processing line (S61).

[0096] The laser light L is then scanned once or several times along the candidate line 5A in the ineffective region 16x as it converges into the interior of the substrate 12, and one or more rows of the modified region 7 are formed within the substrate 12 of the ineffective region 16x. Accordingly, the half-section Hc, which reaches the front surface 12a of the substrate 12 in the ineffective region 16x, is formed along the candidate line 5A (S62). Subsequently, the surface image containing the half-section Hc is imaged by the surface observation unit 211 and stored in the memory unit (ROM or RAM) of the control unit 250.

[0097] The control unit 250 then performs image recognition processing on the stored surface image and detects and evaluates the state of the half-section Hc (S63). It determines whether the crop period of the half-section Hc is equal to or greater than the threshold value (S64). If "No" in S64 (if the crop period is less than the threshold value), the angle in the direction θ of candidate line 5A is changed according to the detection result, and a new candidate line 5A is defined (S65).

[0098] In S65, a direction in the top view, in the direction θ (regardless of whether this is the positive or negative direction), in which the candidate line 5A rotates in the direction of the deflection of the half-section Hc, is obtained as the specified direction of rotation. A specified rotation angle is obtained from the offset period of the half-section Hc using a data function or a data table that has been predefined. The angle of the candidate line 5A in the direction θ is modified so that it deviates by a specified angle in the specified direction of rotation. After S65, the processing returns to S62.

[0099] The threshold can be set based on the cropping period if the angular deviation Δθ between the direction of the crystal orientation K and the direction of the candidate line 5A is sufficiently small. The data function or data table consists of data relating to a correlation 66 (see Fig. 19(b)) between the angle formed by the candidate line 5A with respect to the crystal orientation K and the cropping period (the degree of deflection of the half-section Hc). The threshold and the data function or data table are stored in the memory unit (ROM) of the control unit 250. Moreover, rotating the machining line 5 towards a deflection side of the cropped shape in the direction θ corresponds to rotating the object 1 to a side opposite the deflection side of the cropped shape in the direction θ.

[0100] If yes in S64 (if the crop period is equal to or greater than the threshold), the current candidate line 5A is set as reference line 5B, and the direction of reference line 5B is stored as crystal orientation K in the memory unit of control unit 250 (S66).

[0101] In the Fig. 19(a) and Fig. In the example illustrated in Figure 19(b), laser processing is first performed along a candidate line 5A1 to form a half-section Hc. Since a crop period C1 of the half-section Hc is less than a threshold α, a new candidate line 5A2 is defined. Subsequently, laser processing is performed along candidate line 5A2, and a half-section Hc is formed. Since a crop period C2 of the half-section Hc is still less than a threshold α, a new candidate line 5A3 is defined. Subsequently, laser processing is performed along candidate line 5A3, and a half-section Hc is formed. A crop period C3 of the half-section Hc is equal to or greater than the threshold α. Therefore, candidate line 5A3 is defined as the reference line 5B. Subsequently, in Figure S20, the majority of markings M are formed along the reference line 5B.

[0102] As described above, the present embodiment also exerts the effect described above, namely that it is possible to prevent the cutting line 5C from deviating and being fixed with respect to the crystal orientation K of the substrate 12.

[0103] In the present embodiment, the control unit 250 successively defines the majority of candidate lines 5A for the object 1 to be processed until the degree of deflection of the half-section Hc falls within the specified range (here, the offset period becomes the threshold value α). Subsequently, the candidate line 5A at which the degree of deflection of the half-section Hc falls within the specified range is defined as the reference line 5B. Accordingly, it is possible to define the reference line 5B for the object 1 to be processed with the desired accuracy. For example, by setting the threshold value α to a value at which the crystal orientation K and the direction of the candidate line 5A coincide, a high degree of agreement between the crystal orientation K and the reference line 5B can be achieved.

[0104] In the present embodiment, the control unit 250 defines the initial candidate line 5A1 for the object 1 to be machined using the orientation surface OF with which the object 1 is equipped as a reference. That is, the standard machining line parallel to the orientation surface OF is defined, and the candidate line 5A1 is defined using the standard machining line as a reference. In this case, variations in the definition of the candidate lines 5A for each object 1 to be machined can be prevented.

[0105] The control unit 250 of the present embodiment includes the memory unit that stores the correlation 66 (the data function or data table) between the angle formed by the candidate line 5A with respect to the crystal orientation K and the degree of deflection of the half-section Hc. Accordingly, when defining a new candidate line 5A in S65, the correlation 66 can be used as an index. Consequently, it is possible to reduce the number of candidate lines 5A that are defined successively before the reference line 5B is defined.

[0106] Next, a third embodiment is described. The description of the third embodiment details aspects that differ from the first embodiment.

[0107] In the present embodiment, the control unit 250 defines the plurality of candidate lines 5A for the object 1 to be machined. These candidate lines have different line rotation angles, which are angles in the direction θ formed with respect to a predefined reference direction (hereinafter simply referred to as "line rotation angle"). Here, the reference direction is a direction along the standard machining line and a direction parallel to the orientation surface OF (or inclined at the reference angle in the direction θ).

[0108] The control unit 250 detects the inclination direction in which the half-section (projection) Hc of each of the plurality of candidate lines 5A is inclined with respect to a corresponding candidate line 5A. In a case where the half-section Hc of each of the plurality of candidate lines 5A extends such that it is inclined with respect to each of the plurality of candidate lines 5A, the control unit 250 detects whether the inclination direction with respect to the plurality of candidate lines 5A is to one side or to the other (to the side opposite one side). The inclination direction is a direction of the angular deviation Δθ with respect to the candidate line 5A.The direction of inclination, viewed as extending along the left-right direction of the half-section Hc, can be described as an upward-sloping case, and a downward-sloping case as a "lower side." The direction of inclination of the half-section Hc is independent of whether it has a cranked shape. That is, the half-section Hc can be inclined without having a cranked shape.

[0109] The control unit 250 detects a first candidate line where the inclination direction of the half-section Hc is on one side of candidate line 5A and the line rotation angle is the largest (or smallest) among the multiple candidate lines 5A. The control unit 250 detects a second candidate line where the inclination direction of the half-section Hc is on the other side of candidate line 5A and the line rotation angle is the smallest (or largest) among the multiple candidate lines 5A. That is, when a search for multiple candidate lines 5A is performed to increase or decrease the line rotation angle, the control unit 250 detects candidate line 5A as the first candidate line immediately before the inclination direction of the half-section Hc is reversed, and detects candidate line 5A as the second candidate line immediately after the inclination direction of the half-section Hc has been reversed.

[0110] The control unit 250 then defines the reference line 5B for the object 1 to be processed based on the first candidate line and the second candidate line. Specifically, if an angle formed with respect to the reference direction of the first candidate line is a first line rotation angle, and an angle formed with respect to the reference direction of the second candidate line is a second line rotation angle, the control unit 250 defines the candidate line 5A as reference line 5B. This candidate line has a line rotation angle that is between the first and second line rotation angles. In other words, the candidate line 5A that has a larger (or smaller) line rotation angle than the first candidate line and a smaller (or larger) line rotation angle than the second candidate line is defined as reference line 5B.

[0111] Alternatively, if no candidate line 5A exists that has a line rotation angle equal to the angle between the first and second line rotation angles, the control unit 250 can generate a new line inclined with respect to the reference direction by the angle between the first and second line rotation angles to define the line as reference line 5B. If a plurality of candidate lines 5A exists that correspond to the angle between the first and second line rotation angles, the control unit 250 can appropriately define any one of these plurality of candidate lines 5A as reference line 5B. The control unit 250 can also select the candidate line 5A with the non-inclined half-section Hc from the plurality of candidate lines 5A as reference line 5B.

[0112] As in Fig. As illustrated in Figure 20, the reference line 5B in the laser processing method according to the third embodiment in S10 is defined as follows. That is, first the substrate 12 is placed on the support table 107 of the table 111. The plurality of candidate lines 5A, which have different line rotation angles from one another, are defined for the object 1 to be processed (S31).

[0113] The laser light L is then scanned once or several times along the plurality of candidate lines 5A as it converges into the interior of the substrate 12, and one or more rows of the modified region 7 are formed within the substrate 12. Accordingly, the half-section Hc, which reaches the front surface 12a of the substrate 12, is formed along each of the plurality of candidate lines 5A (S32). Subsequently, the surface image containing the half-section Hc is imaged by the surface observation unit 211 and stored in the memory unit (ROM or RAM) of the control unit 250.

[0114] The control unit 250 then performs image recognition processing on the stored surface image and detects whether the half-section Hc of each of the plurality of candidate lines 5A is inclined with respect to a corresponding candidate line 5A, and the direction of inclination if the half-section Hc is inclined (S33). The control unit 250 identifies the first and second candidate lines from the plurality of candidate lines 5A and selects the candidate line 5A based on these first and second candidate lines. Specifically, the candidate line 5A that corresponds to the line rotation angle between the first and second line rotation angles is selected (S34). The selected candidate line 5A is defined as the reference line 5B, and the direction of the reference line 5B is stored as the crystal orientation K in the memory unit of the control unit 250 (S35).

[0115] Fig. Figure 21(a) is a diagram illustrating an example of a processing result of the laser processing method according to the third embodiment. In the laser processing method of Fig. 21(a) The distance (distance of closest approach) between the majority of candidate lines 5A is set to 100 µm. The laser light output L is 3.5 µJ.

[0116] In the Fig. In the illustrated result (21(a)), the inclination direction of the half-section Hc lies on the upper side at a line rotation angle of 0 degrees to 0.024 degrees, at 0.025 degrees there is no inclination, at 0.026 degrees it is reversed so that it lies on the lower side, and at 0.026 degrees to 0.04 degrees it is on the lower side. The half-section Hc with the line rotation angle of 0.02 degrees to 0.026 degrees does not include the cranked shape. The candidate line 5A, which has a line rotation angle of 0.025 degrees, is defined as the reference line 5B. That is, the direction of the candidate line 5A, which has the line rotation angle of 0.025 degrees, corresponds to the optimal angle (of the crystal orientation K).In this case, candidate line 5A, which has a line rotation angle of 0.024 degrees, is the first candidate line (or the second candidate line), and candidate line 5A, which has a line rotation angle of 0.026 degrees, is the second candidate line (or the first candidate line).

[0117] Fig. Figure 21(b) is a diagram illustrating a further example of the processing result of the laser processing method according to the third embodiment. In the laser processing method of Fig. 21(b) The distance (distance of closest approach) between the majority of candidate lines 5A is set to 50 µm. The laser light output L is 4.5 µJ higher than the output of the laser processing method of Fig. 21(a).

[0118] In the Fig.In the illustrated result of Figure 21(b), the inclination direction of the half-section Hc is also on the upper side for a line rotation angle of 0 degrees to 0.024 degrees; at 0.025 degrees there is no inclination; at 0.026 degrees it is reversed so that it lies on the lower side; and at 0.026 degrees to 0.04 degrees it is on the lower side. The half-section Hc with the line rotation angle of 0.023 degrees to 0.026 degrees does not include the cranked shape. The candidate line 5A, which has a line rotation angle of 0.025 degrees, is defined as the reference line 5B. That is, the direction of the candidate line 5A, which has the line rotation angle of 0.025 degrees, corresponds to the optimal angle (of the crystal orientation K).In this case, candidate line 5A, which has a line rotation angle of 0.024 degrees, is also the first candidate line (or the second candidate line), and candidate line 5A, which has a line rotation angle of 0.026 degrees, is the second candidate line (or the first candidate line).

[0119] As described above, in the present embodiment it is also possible to prevent the cutting line 5C from deviating from and being fixed with respect to the crystal orientation K of the substrate 12 of the object 1 to be machined. Furthermore, it has been found that the angle between the line rotation angle of the first candidate line and the line rotation angle of the second candidate line corresponds to the crystal orientation K of the substrate 12. Therefore, by defining the reference line 5B, which is the line that indicates the crystal orientation K of the substrate 12, the reference line 5B can be determined with high accuracy (with an accuracy of 0.001 degrees) based on the first and second candidate lines.

[0120] The present embodiment can also be applied to a case in which the half-section Hc does not have the cranked shape (that is, the shape of the deflection that is regularly repeated). In the present embodiment, even in a case in which the distance between the majority of candidate lines 5A is set to be 50 µm (for example, in a case in which it is narrower than the distance between the adjacent functional devices 15a), the reference line 5B can be set with high accuracy.

[0121] According to S32, the control unit 250 confirms (determines) that at least one of the plurality of half-cuts Hc of the plurality of candidate lines 5A does not have the cranked shape, and if the cranked shape is not present, it can perform S33 to S35. If, on the other hand, all of the plurality of half-cuts Hc have the cranked shape, the same processing as in the first embodiment or the second embodiment can be carried out without performing S33 to S35. Furthermore, the present embodiment can be carried out if at least one of the plurality of half-cuts Hc does not have the cranked shape in the first embodiment or the second embodiment.

[0122] The embodiments of the present invention have been described above; however, the present invention is not limited to the embodiments described above and can be modified within the scope in which the core concept described in each claim is not changed, or applied to other things.

[0123] In the embodiments described above, the object 1 to be processed is cut along the cutting line 5C by forming the modified area 7 inside the object 1 along the cutting line 5C; however, the step and design for cutting the object 1 are not subject to any particular restrictions. For example, a step and design for cutting the object 1 may involve performing a blade splitting operation with a splitting blade along the cutting line 5C. For example, a step and design for cutting the object 1 may involve performing an ablation operation along the cutting line 5C. Known steps and designs (devices) can be selected, provided that the object 1 can be cut along the cutting line 5C.

[0124] In the above embodiments, either only one row of the modified areas 7 can be formed inside the object 1 to be processed, or two or more rows of the modified areas 7 can be formed, their positions differing from one another in the thickness direction. In the above embodiments, the "laser light entry surface" is the front surface 3 (the front surface 12a), and the "surface opposite the laser light entry surface" is the rear surface 21; in a case where the rear surface 21 is the "laser light entry surface," the front surface 3 is the "surface opposite the laser light entry surface." "Compliance" includes not only exact agreement but also substantial agreement. "Compliance" includes a design defect, a manufacturing defect, and a measurement error.

[0125] An aspect of the present invention can also be considered as a chip manufactured by the laser processing device or laser processing method. An aspect of the present invention can be applied only in a case where the processing line 5 is defined along the direction parallel to the orientation surface OF, or only in a case where the processing line 5 is defined along the direction perpendicular to the orientation surface OF. Furthermore, an aspect of the present invention can be applied in a case where the processing line 5 is defined along the directions parallel and perpendicular to the orientation surface OF. In the above, the control unit 250 forms a candidate line definition unit, an operating control unit, a reference line definition unit, a cutting line definition unit, and a storage unit. Commercial applicability

[0126] In one aspect of the present invention, it is possible to provide a laser processing device and a laser processing method that are able to prevent the cutting line from deviating and being fixed with respect to the crystal orientation of the substrate of the object to be processed. List of reference symbols 1 object to be edited, 3, 12a front surface, 5A Candidate Line, 5B Reference line, 5C cutting line, 7 modified area, 12 substrate, 100, 300 laser processing device, 107 Support table, 202 Laser light source, 204 converging optical system, 211 Area observation unit (imaging unit), 240 display unit, 250 control units (candidate line setting unit, operating control unit, reference line setting unit, cutting line setting unit, storage unit), Hc half-cut (tear), K Crystal orientation, L laser light, M Mark (reference mark), OF orientation area.

Claims

[1] Laser processing device (100, 300) comprising: a support table (107) designed to support an object (1) to be processed, which includes a substrate (12) made of a crystalline material; a laser light source (202) designed to emit laser light (L); a converging optical system (204) designed such that the light emitted by the laser light source (202) is converged onto the object (1) to be processed, which is supported by the support table (107); an imaging unit (211) designed to image a front surface (3, 12a) of the object (1) to be processed, which is supported by the support table (107); a candidate line specification unit (250) designed to specify a plurality of candidate lines (5A) extending in different directions for the object (1) to be processed; an operating control unit (250) designed to control the operation of the support table (107), the laser light source (202) and / or the converging optical system (204) such that a modified area (7) is formed inside the substrate (12) along each of the plurality of candidate lines (5A) and a crack (Hc) reaches the front surface (3, 12a) of the object (1) to be processed from the modified area (7); and a reference line defining unit (250) designed to define for the object (1) to be processed a reference line (5B) which is defined as a line indicating a crystal orientation (K) of the substrate (12) on the basis of an image of the crack (Hc) imaged by the imaging unit (211). [2] Laser processing device (100, 300) according to claim 1, wherein the candidate line specification unit (250) for the object to be processed (1) specifies a predetermined number of candidate lines (5A) extending in different predetermined directions, and The reference line definition unit (250) for the object to be processed (1) selects from the specified number of candidate lines (5A) a candidate line (5A) which has a smallest degree of deflection of the crack (Hc) as reference line (5B). [3] Laser processing device (100, 300) according to claim 2, wherein the candidate line determination unit (250) for the object (1) to be processed determines the predetermined number of candidate lines (5A) extending in different predetermined directions by means of an orientation surface (OF) as a reference with which the object (1) to be processed is equipped. [4] Laser processing device (100, 300) according to claim 1, wherein The candidate line specification unit (250) successively specifies the plurality of candidate lines (5A) for the object (1) to be processed, based on the image of the crack (Hc) that has been imaged by the imaging unit (211), until a degree of deflection of the crack (Hc) falls within a specified range, and The reference line definition unit (250) for the object to be processed (1) defines one of the candidate lines (5A) whose degree of deflection of the crack (Hc) falls within the specified area as the reference line (5B). [5] Laser processing device (100, 300) according to claim 4, wherein the candidate line defining unit (250) defines an initial candidate line (5A) for the object (1) to be processed using an orientation surface (OF) as a reference with which the object (1) to be processed is equipped. [6] Laser processing device (100, 300) according to claim 4 or 5, which further comprises a storage unit (250) which stores in advance a relationship between an angle formed by the candidate line with respect to the crystal orientation (K) and a degree of deflection of the crack (Hc). [7] Laser processing device (100, 300) according to one of claims 1 to 6, wherein the candidate line specification unit (250) for the object to be processed (1) specifies the plurality of candidate lines (5A) which have different angles formed with respect to a reference direction, the reference line defining unit (250) recognizes a direction of inclination in which the crack (Hc) of each of the plurality of candidate lines (5A) is inclined with respect to a corresponding candidate line (5A), and the reference line definition unit (250) defines the reference line (5B) for the object to be processed (1) on the basis of a first candidate line (5A) whose inclination direction of the crack (Hc) is on one side of a corresponding candidate line (5A) and which has a smallest or largest angle formed with respect to the reference direction, and a second candidate line (5A) whose inclination direction of the crack (Hc) is on another side of a corresponding candidate line (5A) and which has a smallest or largest angle formed with respect to the reference direction, from the plurality of candidate lines (5A). [8] Laser processing device (100, 300) according to one of claims 1 to 7, which further comprises a display unit (240) designed to display the image of the crack (Hc) that has been imaged by the imaging unit (211). [9] Laser processing device (100, 300) according to one of claims 1 to 8, wherein the operating control unit (250) controls the operation of the support table (107), the laser light source (202) and / or the converging optical system (204) such that a reference mark indicating the crystal orientation (K) is formed on the object (1) to be processed along the reference line (5B) which has been defined by the reference line defining unit (250). [10] Laser processing device (100, 300) according to one of claims 1 to 9, which further comprises a cutting line definition unit (250) designed to define a cutting line (5C) for the object (1) to be processed, which extends in a direction parallel to the reference line (5B) defined by the reference line definition unit (250), wherein the operating control unit (250) controls the operation of the support table (107), the laser light source (202) and / or the converging optical system (204) such that the modified area (7) inside the substrate (12) is formed along the cutting line (5C) that has been defined by the cutting line definition unit (250). [11] Laser processing method which features: a first step to determine a plurality of candidate lines (5A) extending in different directions for a work object (1) which includes a substrate (12) made of a crystalline material; a second step to converge a laser light (L) onto the object to be processed (1) such that a modified area (7) is formed inside the substrate (12) along each of the plurality of candidate lines (5A) and a crack (Hc) reaches a front surface (3, 12a) of the object to be processed (1) from the modified area (7); and a third step to establish a reference line (5B) for the object (1) to be processed, which is determined as a line that specifies a crystal orientation (K) of the substrate (12) based on a state of the crack (Hc). [12] Laser processing method according to claim 11, wherein In the first step, a predetermined number of candidate lines (5A), extending in different predetermined directions, are defined for the object (1) to be processed, and In the third step, from the given number of candidate lines (5A), a candidate line (5A) which has the smallest degree of deflection of the crack (Hc) is selected as the reference line (5B) for the object (1) to be processed. [13] Laser processing method according to claim 11, wherein In the first step, based on a state of the crack (Hc), the majority of candidate lines (5A) are successively determined for the object (1) to be processed, until a degree of deflection of the crack (Hc) falls within a predetermined range, and In the third step, one of the candidate lines (5A), whose degree of deflection of the crack (Hc) falls within the specified area, is defined as the reference line (5B) for the object (1) to be processed. [14] Laser processing method according to any one of claims 11 to 13, wherein in the first step the majority of candidate lines (5A), which have different angles formed with respect to a reference direction, is determined for the object (1) to be processed, and in the third step a direction of inclination is identified in which the crack (Hc) of each of the plurality of candidate lines (5A) is inclined with respect to a corresponding of the candidate lines (5A), and the reference line (5B) for the object (1) to be processed is determined on the basis of a first candidate line (5A), the inclination direction of which of the crack (Hc) is on one side of a corresponding candidate line (5A) and which has a smallest or largest angle formed with respect to the reference direction, and a second candidate line (5A), the inclination direction of which of the crack (Hc) is on another side of a corresponding candidate line (5A) and which has a smallest or largest angle formed with respect to the reference direction, from the plurality of candidate lines (5A).

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