Laser processing apparatus and laser processing method

Abstract

A laser processing apparatus includes an irradiation section configured to irradiate an object with laser light, an imaging section configured to image the object, and a control section configured to control at least the irradiation section and the imaging section. A plurality of lines are provided in the object. The control section performs a first process of irradiating the object with the laser light along each of the plurality of lines to form modified points and cracks extending from the modified points in the object in a manner that does not reach an outer surface of the object by control of the irradiation section. The control section performs a second process of imaging the object with light that is transmissive with respect to the object by control of the imaging section after the first process to acquire information indicating a formation state of the modified points and / or the cracks for each of the plurality of lines.

Description

TECHNICAL FIELD

[0001] The present application relates to a laser processing apparatus and a laser processing method. BACKGROUND

[0002] In Patent Literature 1, a laser cutting apparatus is described. The laser cutting apparatus is provided with a stage that moves a wafer, a laser head that irradiates the wafer with laser light, and a control section that controls each part. The laser head has a laser light source that emits processing laser light for forming a modified region inside the wafer, a dichroic mirror and a condenser lens that are sequentially arranged on an optical path of the processing laser light, and an AF device.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent No. 5743123 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, in order to adjust the irradiation condition of laser light with respect to an unknown object whose correlation between the irradiation condition and the processing result is not grasped to a condition in which a desired processing result can be obtained, it is considered to go through the following procedure. That is, laser processing is performed under a plurality of irradiation conditions that are different from each other. Then, the object is cut in a manner that a cross section in which a modified region or the like is formed is exposed. Then, by observing the cut surface, the actual processing result with respect to the plurality of irradiation conditions that are different from each other is grasped.

[0008] On the other hand, in such a method, when the irradiation condition is adjusted, not only time is consumed but also rich knowledge of cross section observation is required. Therefore, in the technical field described above, it is desired to simplify the adjustment of the irradiation condition.

[0009] The present application has an object to provide a laser processing apparatus and a laser processing method that can simplify the adjustment of the irradiation condition of laser light.

[0010] TECHNICAL MEANS FOR SOLVING THE PROBLEMS

[0011] The laser processing device of the present application includes: an irradiation section for irradiating a target object with laser light; an imaging section for imaging the target object; and a control section for controlling at least the irradiation section and the imaging section. In the target object, a plurality of lines are set. The control section performs: a first process for forming a modified point and a crack extending from the modified point in the target object in such a manner that the outer surface of the target object is not reached by irradiating the target object with laser light along each of the plurality of lines; and a second process for acquiring information indicating a formation state of the modified point and / or the crack for each of the plurality of lines by imaging the target object with light that is transmissive with respect to the target object after the first process. In the first process, laser light is irradiated onto the target object under different irradiation conditions for each of the plurality of lines. In the second process, the information indicating the irradiation conditions in the first process and the information indicating the formation state are associated with each other for each of the plurality of lines.

[0012] The laser processing method of the present application includes: a first step for forming a modified point and a crack extending from the modified point in a target object in such a manner that the outer surface of the target object is not reached by irradiating the target object with laser light along each of a plurality of lines set in the target object; and a second step for acquiring information indicating a formation state of the modified point and / or the crack for each of the plurality of lines by imaging the target object with light that is transmissive with respect to the target object after the first step. In the first step, laser light is irradiated onto the target object under different irradiation conditions for each of the plurality of lines. In the second step, the information indicating the irradiation conditions in the first step and the information indicating the formation state are associated with each other for each of the plurality of lines.

[0013] In these devices and methods, the target object is irradiated with laser light along each of a plurality of lines to form a modified point and the like (modified point and crack extending from the modified point). At this time, the irradiation conditions are set to be different for each line. Then, the target object is imaged with light that is transmissive with respect to the target object to acquire a formation state (processing result) of the modified point and the like for each of the plurality of lines. Further, the irradiation conditions of the laser light and the formation state of the modified point and the like are associated with each other for each of the plurality of lines. Therefore, when the irradiation conditions of the laser light are adjusted, it is not necessary to cut the target object or perform cross-sectional observation. Therefore, according to the devices and methods, it is possible to simplify the adjustment of the irradiation conditions of the laser light.

[0014] In the laser processing device of the present application, the control section can perform: a third process for determining whether the irradiation conditions are conditions in which the crack does not reach the outer surface, i.e., non-reached conditions, before the first process, and the first process can be performed when the result of the determination in the third process is that the irradiation conditions are the non-reached conditions. In this case, it is possible to reliably perform processing in such a manner that the crack does not reach the outer surface of the target object.

[0015] The laser processing apparatus of the present application can also include a display section for displaying information, and an input section for accepting input. In this case, information can be presented to the user, and input of information from the user can be accepted.

[0016] In the laser processing apparatus of the present application, the control section can perform a fourth process of causing information acquired by the second process to be displayed on the display section by control of the display section after the second process. In this case, information in which the irradiation conditions of the respective lasers are correlated with the formation state of the modified points or the like can be displayed.

[0017] In the laser processing apparatus of the present application, the control section can perform a fifth process of making a determination as to whether or not the cracks have reached the outer surface based on the information indicating the formation state acquired by the second process after the second process and before the fourth process, and performing the fourth process in the case where the determination of the fifth process results in the cracks not having reached the outer surface. In this case, the irradiation conditions of the lasers and the formation state of the modified points or the like can be reliably displayed in correlation with each other in the state where the cracks have not reached the outer surface of the object.

[0018] In the laser processing apparatus of the present application, the control section can perform a sixth process of causing information for facilitating selection of a variable item that differs for each line among a plurality of irradiation condition items included in the irradiation conditions in the first process to be displayed on the display section before the first process, the input section accepting input of the selection of the variable item, and the control section performing the first process in a manner in which the variable item accepted by the input section differs for each line by control of the irradiation section. In this case, adjustment of the desired irradiation conditions becomes easy.

[0019] In the laser processing apparatus of the present application, the irradiation conditions can include at least one of the following items as the irradiation condition items: a pulse waveform of the laser; a pulse energy of the laser; a pulse pitch of the laser; a condensing state of the laser; and a pitch of the modified points in the direction intersecting the incident surface of the laser of the object in the case where a plurality of modified points are formed at positions different from each other in the direction intersecting the incident surface in the first process.

[0020] In this case, the laser processing apparatus of the present application can also include a spatial light modulator that displays a spherical aberration correction pattern for correcting spherical aberration of the laser, and a condensing lens for condensing the laser modulated by the spherical aberration correction pattern in the spatial light modulator to the object, the condensing state including an offset amount of the center of the spherical aberration correction pattern with respect to the center of the pupil face of the condensing lens.

[0021] In these cases, adjustment of the above-described items among the irradiation conditions of the laser becomes easy.

[0022] In the laser processing apparatus of the present application, it can also be that, in a case where the peak of the formation state is acquired by the second processing, in the fourth processing, the irradiation condition corresponding to the peak is displayed on the display by the control of the display. In this case, it is possible to easily adjust the irradiation condition of the laser to a condition in which the formation state of the modified point or the like becomes a peak.

[0023] In the laser processing apparatus of the present application, it can also be that the object includes a first surface that is an incident surface of the laser, a second surface on the opposite side of the first surface, the crack includes a first crack extending from the modified point to the first surface side, a second crack extending from the modified point to the second surface side, and the formation state includes at least one of the following items as a formation state item: a length of the first crack in a first direction intersecting the first surface; a length of the second crack in the first direction; a total amount of the lengths of the cracks in the first direction; a position of a first end that is a front end of the first surface side of the first crack in the first direction; a position of a second end that is a front end of the second surface side of the second crack in the first direction; a deviation width of the first end and the second end when viewed from the first direction; presence or absence of a trace of the modified point; an amount of meandering of the second end when viewed from the first direction; and, in a case where a plurality of modified points are formed at positions different from each other in a direction intersecting the first surface in the first processing, presence or absence of a front end of a crack of a region between the modified points arranged in the direction intersecting the first surface. In this case, adjustment of the irradiation condition of the laser in the formation state of the modified point or the like according to the above items becomes easy.

[0024] Effects of the Invention

[0025] According to the present application, it is possible to provide a laser processing apparatus and a laser processing method that can simplify adjustment of an irradiation condition of a laser. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic view showing a structure of a laser processing apparatus of an embodiment.

[0027] Figure 2 is a plan view of a wafer of an embodiment.

[0028] Figure 3 is a cross-sectional view of a portion of the wafer shown in Figure 2

[0029] Figure 4 is a schematic view showing a structure of a laser irradiation unit shown in Figure 1

[0030] Figure 5 is a view showing a relay lens unit shown in Figure 4

[0031] ​​​Figure 6 is a sectional view of the spatial light modulator shown in FIG. 1. Figure 4

[0032] Figure 7 is a schematic view of the structure of the imaging unit shown in FIG. 1. Figure 1

[0033] Figure 8 Figure 1

[0034] Figure 9 Figure 7

[0035] Figure 10 Figure 7

[0036] Figure 11

[0037] Figure 12

[0038] Figure 13 Figure 7

[0039] Figure 14 Figure 7

[0040] Figure 15 Figure 7

[0041] Figure 16 Figure 7

[0042] Figure 17

[0043] ​​​​​​​​​​​​​​​​​​​Figure 18 is a graph showing the change in the amount of cracks in the case where the interval of the modified region is changed at 3 points.

[0044] Figure 19 is a graph showing the change in the amount of cracks in the case where the interval of the modified region is changed at 3 points.

[0045] Figure 20 is a graph showing the change in the amount of cracks in the case where the pulse width of the laser light is changed at 3 points.

[0046] Figure 21 is a graph showing the change in the amount of cracks in the case where the pulse width of the laser light is changed at 3 points.

[0047] Figure 22 is a graph showing the change in the amount of cracks in the case where the pulse energy of the laser light is changed at 3 points.

[0048] Figure 23 is a graph showing the change in the amount of cracks in the case where the pulse energy of the laser light is changed at 3 points.

[0049] Figure 24 is a graph showing the change in the amount of cracks in the case where the pulse interval of the laser light is changed at 4 points.

[0050] Figure 25 is a graph showing the change in the amount of cracks in the case where the pulse interval of the laser light is changed at 4 points.

[0051] Figure 26 is a graph showing the change in the amount of cracks in the case where the condensing state of the laser light (spherical aberration correction level) is changed at 3 points.

[0052] Figure 27 is a graph showing the change in the amount of cracks in the case where the condensing state of the laser light (spherical aberration correction level) is changed at 3 points.

[0053] Figure 28 is a graph showing the change in the amount of cracks in the case where the condensing state of the laser light (astigmatism correction level) is changed at 3 points.

[0054] Figure 29 is a graph showing the change in the amount of cracks in the case where the condensing state of the laser light (astigmatism correction level) is changed at 3 points.

[0055] Figure 30 is a graph showing the change in the presence or absence of black streaks in the case where the pulse interval of the laser light is changed at 4 points.

[0056] Figure 31 is a graph showing the change in the presence or absence of black streaks in the case where the pulse interval of the laser light is changed at 4 points.

[0057] Figure 32 is a flowchart showing main procedures of the eligibility determination method.

[0058] Figure 33 is a diagram showing a state of the input accepting section. Figure 1

[0059] Figure 34 is a diagram showing a state of the input accepting section.

[0060] Figure 35 is a diagram showing a state of the input accepting section.

[0061] Figure 36 is a diagram showing a state of the input accepting section.

[0062] Figure 37 is a diagram showing a state of the input accepting section.

[0063] Figure 38 is a diagram showing a state of the input accepting section.

[0064] Figure 39 is a flowchart showing main procedures of the irradiation condition derivation method.

[0065] Figure 40 is a diagram showing an example of the input accepting section. Figure 1

[0066] is a diagram showing a state of the input accepting section. Figure 41

[0067] Figure 42 is a diagram showing a state of the input accepting section.

[0068] Figure 43 is a coordinate diagram showing a relationship between the irradiation condition and the formation state.

[0069] Figure 44 is a diagram showing a relationship between the Y offset and the formation state.

[0070] Figure 45 is a flowchart showing main procedures of the LBA offset derivation method.

[0071] Figure 46 is a flowchart showing main procedures of the LBA offset derivation method.

[0072] ​​Figure 47 is a diagram of an input receiving section indicating a state in which a screen showing a selection of a check condition is displayed.

[0073] Figure 48 is a diagram of an input receiving section indicating a state in which a screen showing a setting screen is displayed.

[0074] Figure 49 is a diagram of an input receiving section indicating a state in which a screen showing information indicating a processing result is displayed.

[0075] Figure 50 is a diagram indicating a relationship between a Y offset amount and a determination item.

[0076] Figure 51 is a diagram indicating a relationship between a Y offset amount and a determination item.

[0077] Figure 52 is a diagram indicating a relationship between a Y offset amount and a determination item.

[0078] Figure 53 is a diagram indicating a relationship between a Y offset amount and a determination item.

[0079] Figure 54 is a diagram indicating a relationship between an X offset amount and a determination item.

[0080] Figure 55 is a diagram indicating a relationship between an X offset amount and a determination item.

[0081] Figure 56 is a diagram indicating a relationship between an X offset amount and a determination item. DETAILED DESCRIPTION

[0082] Hereinafter, an embodiment will be described in detail with reference to the drawings. In each drawing, the same or equivalent portions are assigned the same reference numerals, and overlapping descriptions will be omitted. In each drawing, there are cases in which a rectangular coordinate system defined by an X axis, a Y axis, and a Z axis is indicated.

[0083] Figure 1 is a diagram indicating a structure of a laser processing apparatus of an embodiment. As shown in Figure 1 , the laser processing apparatus 1 is provided with a stage 2, a laser irradiation unit 3, a plurality of imaging units 4, 7, 8, a drive unit 9, and a control section 10. The laser processing apparatus 1 is an apparatus that forms a modified region 12 in an object 11 by irradiating the object 11 with laser light L.

[0084] The stage 2 supports the object 11, for example, by adsorbing a film attached to the object 11. The stage 2 is movable in the X direction and the Y direction, respectively, and rotatable about an axis parallel to the Z direction as a center line. In addition, the X direction and the Y direction are a first horizontal direction and a second horizontal direction that intersect (orthogonal to) each other, and the Z direction is a vertical direction.

[0085] The laser irradiation unit (irradiation section) 3 condenses and irradiates laser light L having transmissivity with respect to the object 11 to the object 11. When the laser light L is condensed to the inside of the object 11 supported by the stage 2, the laser light L is particularly absorbed at a portion corresponding to a condensing point C of the laser light L, and a modified region 12 is formed in the inside of the object 11.

[0086] The modified region 12 is a region having a density, a refractive index, a mechanical strength, or other physical characteristics different from those of a surrounding unmodified region. As the modified region 12, for example, there are a fusion-processed region, a crack region, an insulation-destroyed region, a refractive index variation region, and the like. The modified region 12 can be formed in such a manner that a crack extends from the modified region 12 to the incident side and the opposite side of the laser light L. Such a modified region 12 and a crack are used, for example, for cutting of the object 11.

[0087] As one example, if the stage 2 is moved in the X direction so that the condensing point C relatively moves in the X direction with respect to the object 11, a plurality of modified points 12s are formed in such a manner that they are arranged in one column in the X direction. One modified point 12s is formed by irradiation of the laser light L with one pulse. One column of modified regions 12 is a collection of a plurality of modified points 12s arranged in one column. Therefore, the modified point 12s is the same as the modified region 12, and is a point having a density, a refractive index, a mechanical strength, or other physical characteristics different from those of a surrounding unmodified portion. Adjacent modified points 12s, depending on the relative moving speed of the condensing point C with respect to the object 11 and the repetition frequency of the laser light L, can be connected to each other or can be separated from each other.

[0088] The imaging unit (imaging section) 4 images the modified region 12 formed in the object 11 and the front end of the crack extending from the modified region 12 (details will be described later). The imaging units 7 and 8 image the object 11 supported by the stage 2 using light transmitted through the object 11 in accordance with the control of the control section 10. The image obtained by imaging by the imaging units 7 and 8 is used, as one example, for alignment of the irradiation position of the laser light L.

[0089] The drive unit 9 supports the laser irradiation unit 3 and the plurality of imaging units 4, 7, and 8. The drive unit 9 moves the laser irradiation unit 3 and the plurality of imaging units 4, 7, and 8 in the Z direction.

[0090] The control section 10 controls the operations of the stage 2, the laser irradiation unit 3, the plurality of imaging units 4, 7, 8, and the drive unit 9. The control section 10 has a processing section 101, a storage section 102, and an input accepting section (display section, input section) 103. The processing section 101 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like. In the processing section 101, the processor executes software (program) read in the memory or the like, controls reading and writing of data in the memory and the storage, and communication performed by the communication device. The storage section 102 is, for example, a hard disk or the like, and stores various data. The input accepting section 103 is an interface section that displays various information and accepts input of various information from a user. In the present embodiment, the input accepting section 103 configures a GUI (Graphical User Interface).

[0091] [Structure of Object]

[0092] Figure 2 is a plan view of a wafer of an embodiment. Figure 3 is Figure 2 is a cross-sectional view of a part of the wafer shown in FIG. 1. The object 11 of the present embodiment is, as one example, a wafer 20 shown in FIG. 2. Figure 2 , 3 The wafer 20 has a semiconductor substrate 21, a functional element layer 22. The semiconductor substrate 21 has a surface 21a and a back surface 21b. As one example, the back surface 21b is a first surface that is an incident surface of a laser L or the like, and the surface 21a is a second surface on the opposite side of the first surface. The semiconductor substrate 21 is, for example, a silicon substrate. The functional element layer 22 is formed on the surface 21a of the semiconductor substrate 21. The functional element layer 22 includes a plurality of functional elements 22a arranged two-dimensionally along the surface 21a.

[0093] The functional element 22a is, for example, a light-receiving element such as a photodiode, a light-emitting element such as a laser diode, a circuit element such as a memory, or the like. The functional element 22a can also be configured three-dimensionally by stacking a plurality of layers. In addition, in the semiconductor substrate 21, a groove 21c indicating a crystal orientation is provided, but instead of the groove 21c, an orientation flat can be provided. In addition, the object 11 can be a bare wafer.

[0094] The wafer 20 is cut along each of the plurality of lines 15 for each functional element 22a. The plurality of lines 15, when viewed from the thickness direction of the wafer 20, pass between each of the plurality of functional elements 22a. More specifically, the plurality of lines 15, when viewed from the thickness direction of the wafer 20, pass through the center (center in the width direction) of the street region 23. The street region 23 extends in the functional element layer 22 in such a way that it passes between adjacent functional elements 22a. In this embodiment, the plurality of functional elements 22a are arranged in a matrix along the surface 21a, and the plurality of lines 15 are set in a lattice pattern. Furthermore, the lines 15 are imaginary lines, but could also be actually drawn lines.

[0095] [Structure of the laser irradiation unit]

[0096] Figure 4 It means Figure 1 The diagram shows the structure of the laser irradiation unit. Figure 5 It means Figure 4 The diagram shows the relay lens unit. Figure 6 yes Figure 4 A cross-sectional view of the locality of the spatial light modulator is shown. (See diagram below.) Figure 4 As shown, the laser irradiation unit 3 includes a light source 31, a spatial light modulator 5, a condenser lens 33, and a 4f lens unit 34. The light source 31 outputs laser light L, for example, through pulse oscillation. Alternatively, the laser irradiation unit 3 may be configured without a light source 31, and the laser light L may be introduced from outside the laser irradiation unit 3.

[0097] The spatial light modulator 5 modulates the laser L output from the light source 31. The condenser lens 33 focuses the laser L modulated by the spatial light modulator 5. The 4f lens unit 34 has a pair of lenses 34A and 34B arranged in the optical path of the laser L from the spatial light modulator 5 toward the condenser lens 33. The pair of lenses 34A and 34B constitute a telecentric optical system with the reflecting surface 5a of the spatial light modulator 5 and the entrance pupil surface (pupil surface) 33a of the condenser lens 33 forming an imaging relationship. Thus, the image of the laser L on the reflecting surface 5a of the spatial light modulator 5 (the image of the laser L modulated in the spatial light modulator 5) is transferred (imaged) onto the entrance pupil surface 33a of the condenser lens 33.

[0098] The spatial light modulator 5 is a spatial light modulator (SLM) of reflective liquid crystal on silicon (LCOS). The spatial light modulator 5 is constructed by sequentially stacking a driving circuit layer 52, a pixel electrode layer 53, a reflective film 54, an alignment film 55, a liquid crystal layer 56, an alignment film 57, a transparent conductive film 58, and a transparent substrate 59 on a semiconductor substrate 51.

[0099] The semiconductor substrate 51 is, for example, a silicon substrate. The drive circuit layer 52 constitutes an active matrix circuit on the semiconductor substrate 51. The pixel electrode layer 53 includes a plurality of pixel electrodes 53a arranged in a matrix shape along the surface of the semiconductor substrate 51. Each pixel electrode 53a is formed of, for example, a metal material such as aluminum. A voltage is applied to each pixel electrode 53a through the drive circuit layer 52.

[0100] The reflective film 54 is, for example, a dielectric multilayer film. The alignment film 55 is provided on the surface of the liquid crystal layer 56 on the side of the reflective film 54, and the alignment film 57 is provided on the surface of the liquid crystal layer 56 on the side opposite to the reflective film 54. Each of the alignment films 55, 57 is formed of, for example, a high molecular material such as polyimide, and a rubbing process is applied to the contact surface of each of the alignment films 55, 57 with the liquid crystal layer 56, for example. The alignment films 55, 57 align the liquid crystal molecules 56a included in the liquid crystal layer 56 in a certain direction.

[0101] The transparent conductive film 58 is provided on the surface of the transparent substrate 59 on the side of the alignment film 57, and opposes the pixel electrode layer 53 with the liquid crystal layer 56 and the like interposed therebetween. The transparent substrate 59 is, for example, a glass substrate. The transparent conductive film 58 is formed of, for example, a light-transmissive and conductive material such as ITO. The transparent substrate 59 and the transparent conductive film 58 transmit the laser light L.

[0102] In the spatial light modulator 5 configured as described above, when a signal representing a modulation pattern is input from the control section 10 to the drive circuit layer 52, a voltage corresponding to the signal is applied to each pixel electrode 53a, and an electric field is formed between each pixel electrode 53a and the transparent conductive film 58. If this electric field is formed, in the liquid crystal layer 56, the alignment direction of the liquid crystal molecules 216a changes in each region corresponding to each pixel electrode 53a, and the refractive index changes in each region corresponding to each pixel electrode 53a. This state is a state in which a modulation pattern is displayed in the liquid crystal layer 56.

[0103] In the state in which a modulation pattern is displayed in the liquid crystal layer 56, when laser light L is incident on the liquid crystal layer 56 from the outside via the transparent substrate 59 and the transparent conductive film 58, is reflected by the reflective film 54, and is emitted from the liquid crystal layer 56 to the outside via the transparent conductive film 58 and the transparent substrate 59, the laser light L is modulated in correspondence with the modulation pattern displayed in the liquid crystal layer 56. In this way, according to the spatial light modulator 5, by appropriately setting the modulation pattern displayed in the liquid crystal layer 56, modulation of the laser light L (for example, modulation of the intensity, amplitude, phase, polarization, and the like of the laser light L) can be performed.

[0104] In the present embodiment, the laser irradiation unit 3 irradiates the wafer 20 with the laser L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15, thereby forming 2 columns of modified regions 12a, 12b inside the semiconductor substrate 21 along each of the plurality of lines 15. The modified region (1st modified region) 12a is the modified region closest to the surface 21a among the 2 columns of modified regions 12a, 12b. The modified region (2nd modified region) 12b is the modified region closest to the modified region 12a among the 2 columns of modified regions 12a, 12b, and is the modified region closest to the back surface 21b.

[0105] The 2 columns of modified regions 12a, 12b are adjacent in the thickness direction (Z direction) of the wafer 20. The 2 columns of modified regions 12a, 12b are formed by relatively moving the 2 focal points O1, O2 along the line 15 with respect to the semiconductor substrate 21. The laser L is modulated by the spatial light modulator 5, for example, in a manner such that the focal point O2 is located on the rear side in the traveling direction with respect to the focal point O1 and the incident side of the laser L.

[0106] The laser irradiation unit 3, as one example, can irradiate the wafer 20 with the laser L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15 in a manner such that the cracks 14 that span the 2 columns of modified regions 12a, 12b reach the surface 21a of the semiconductor substrate 21. As one example, with respect to the semiconductor substrate 21 that is a single-crystal silicon substrate having a thickness of 775 μm, the 2 focal points O1, O2 are aligned with positions 54 μm and 128 μm from the surface 21a, respectively, and the wafer 20 is irradiated with the laser L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15.

[0107] At this time, the wavelength of the laser L is 1099 nm, the pulse width is 700 nsec, and the repetition frequency is 120 kHz. In addition, the output of the laser L at the focal point O1 is 2.7 W, the output of the laser L at the focal point O2 is 2.7 W, and the relative moving speed of the 2 focal points O1, O2 with respect to the semiconductor substrate 21 is 800 mm / sec.

[0108] The formation of such 2 columns of modified regions 12a, 12b and cracks 14 is performed in the following case. That is, it is a case in which, in a subsequent process, the semiconductor substrate 21 is thinned by polishing the back surface 21b of the semiconductor substrate 21, and the cracks 14 are exposed at the back surface 21b, and the wafer 20 is cut into a plurality of semiconductor devices along each of the plurality of lines 15. However, the laser irradiation unit 3 can also form the modified regions (modified points) 12a, 12b and the cracks 14 extending from the modified regions 12a, 12b in the semiconductor substrate 21 in a manner such that the outer surfaces (the surface 21a and the back surface 21b) of the semiconductor substrate 21 are not reached, as described later.

[0109] [Structure of the imaging unit]

[0110] Figure 7 is a schematic view of the structure of the imaging unit shown in Figure 1 . As shown in Figure 7 , the imaging unit 4 has a light source 41, a mirror 42, an objective lens 43, and a light detection section 44. The light source 41 outputs light I1 having a transmittance with respect to the wafer 20 (at least the semiconductor substrate 21). The light source 41 is configured by, for example, a halogen lamp and a filter, and outputs light I1 in the near-infrared region. The light I1 output from the light source 41 is reflected by the mirror 42 and passes through the objective lens 43 to be irradiated to the wafer 20 from the back surface 21b side of the semiconductor substrate 21. At this time, the stage 2 supports the wafer 20 on which the two rows of modification regions 12a and 12b are formed, as described above.

[0111] The objective lens 43 passes the light I1 reflected by the surface 21a of the semiconductor substrate 21. That is, the objective lens 43 passes the light I1 propagating in the semiconductor substrate 21. The numerical aperture (NA) of the objective lens 43 is 0.45 or more. The objective lens 43 has a correction ring 43a. The correction ring 43a corrects aberration of the light I1 occurring in the semiconductor substrate 21, for example, by adjusting the distances between the plurality of lenses configuring the objective lens 43. The light detection section 44 detects the light I1 that has passed through the objective lens 43 and the mirror 42. The light detection section 44 is configured by, for example, an infrared camera including an InGaAs camera, and detects the light I1 in the near-infrared region. That is, the imaging unit 4 is used to image the semiconductor substrate 21 using the light I1 having a transmittance with respect to the semiconductor substrate 21. In addition, as a structure for correcting aberration of the light I1, a spatial light modulator 5 or another structure can be employed instead of (or in addition to) the above-described correction ring 43a. In addition, the light detection section 44 is not limited to an InGaAs camera, and can be any imaging mechanism using a transmissive imaging such as a transmissive confocal microscope.

[0112] The imaging unit 4 can image each of the two rows of modification regions 12a and 12b, and the leading ends of each of the plurality of cracks 14a, 14b, 14c, and 14d (details will be described later). The crack 14a is a crack extending from the modification region 12a toward the surface 21a side. The crack 14b is a crack extending from the modification region 12a toward the back surface 21b side. The crack 14c is a crack extending from the modification region 12b toward the surface 21a side. The crack 14d is a crack extending from the modification region 12b toward the back surface 21b side.

[0113] That is, the cracks 14b, 14d are first cracks extending from the modified regions 12a, 12b toward the back surface 21b side as a first surface, and the cracks 14a, 14c are second cracks extending from the modified regions 12a, 12b toward the surface 21a side as a second surface. Hereinafter, in association with the case where the positive direction of the Z direction is upward, there is also a case where the crack 14d in the first cracks is referred to as an upper crack, and the crack 14a in the second cracks is referred to as a lower crack.

[0114] [Structure of imaging unit for alignment correction]

[0115] Figure 8 is a schematic view of the structure of the imaging unit shown in Figure 1 . As shown in Figure 8 , the imaging unit 7 has a light source 71, a mirror 72, a lens 73, and a light detection section 74. The light source 71 outputs light I2 having transmittance with respect to the semiconductor substrate 21. The light source 71 is constituted by, for example, a halogen lamp and a filter, and outputs light I2 in the near-infrared region. The light source 71 can also be common to the light source 41 of the imaging unit 4. The light I2 output from the light source 71 is reflected by the mirror 72 and passes through the lens 73, and is irradiated to the wafer 20 from the back surface 21b side of the semiconductor substrate 21.

[0116] The lens 73 passes the light I2 reflected by the surface 21a of the semiconductor substrate 21. That is, the objective lens 73 passes the light I2 propagating in the semiconductor substrate 21. The numerical aperture of the lens 73 is 0.3 or less. That is, the numerical aperture of the objective lens 43 of the imaging unit 4 is larger than the numerical aperture of the lens 73. The light detection section 74 detects the light I2 that has passed through the lens 73 and the mirror 72. The light detection section 74 is constituted by, for example, an infrared camera including an InGaAs camera, and detects the light I2 in the near-infrared region.

[0117] The imaging unit 7 irradiates the light I2 to the wafer 20 from the back surface 21b side and detects the light I2 returned from the surface 21a (the functional element layer 22) in accordance with the control of the control section 10, thereby imaging the functional element layer 22. Also, the imaging unit 7 irradiates the light I2 to the wafer 20 from the back surface 21b side and detects the light I2 returned from the formation positions of the modified regions 12a, 12b of the semiconductor substrate 21 in accordance with the control of the control section 10, thereby acquiring images of regions including the modified regions 12a, 12b. These images are used for alignment of the irradiation position of the laser L. The imaging unit 8 has the same structure as the imaging unit 7 except that the lens 73 is of a lower magnification (for example, 6 times in the imaging unit 7 and 1.5 times in the imaging unit 8), and is used for alignment in the same manner as the imaging unit 7. Also, in the imaging units 4, 7, 8, the lens 73 can be shared between imaging for acquisition of the formation state as described above and imaging for alignment as described above.

[0118] [Principle of imaging by the imaging unit]

[0119] Using the imaging unit 4, as shown in Figure 9 Fig. 6, the focal point F (focal point of the objective lens 43) is moved from the back surface 21b side toward the surface 21a side with respect to the semiconductor substrate 21 on which the cracks 14 that cross the two rows of modification regions 12a, 12b do not reach the surface 21a. In this case, even if the focal point F is aligned with the front end 14e of the crack 14 that extends from the modification region 12a toward the surface 21a side from the back surface 21b side, the front end 14e cannot be confirmed (image on the left side of Figure 9 Fig. 7). However, if the focal point F is aligned with the region on the opposite side of the surface 21a from the back surface 21b (i.e., the region on the functional element layer 22 side with respect to the surface 21a) with respect to the surface 21a and the virtual focal point Fv symmetrical to the focal point F with respect to the surface 21a is located at the front end 14e, the front end 14e can be confirmed (image on the right side of Figure 9 Fig. 7). In addition, the virtual focal point Fv is a point symmetrical to the focal point F with respect to the surface 21a taking into account the refractive index of the semiconductor substrate 21.

[0120] In addition, using the imaging unit 4, as shown in Figure 10 Fig. 8, the focal point F is moved from the back surface 21b side toward the surface 21a side with respect to the semiconductor substrate 21 on which the cracks 14 that cross the two rows of modification regions 12a, 12b reach the surface 21a. In this case, even if the focal point F is aligned with the front end 14e of the crack 14 that extends from the modification region 12b toward the back surface 21b side from the back surface 21b side, the front end 14e cannot be confirmed (image on the left side of Figure 10 Fig. 9). However, if the focal point F is aligned with the region on the opposite side of the surface 21a from the back surface 21b (i.e., the region on the functional element layer 22 side with respect to the surface 21a) with respect to the surface 21a and the virtual focal point Fv symmetrical to the focal point F with respect to the surface 21a is located at the front end 14e, the front end 14e can be confirmed (image on the right side of Figure 10 Fig. 9). In addition, the virtual focal point Fv is a point symmetrical to the focal point F with respect to the surface 21a taking into account the refractive index of the semiconductor substrate 21.

[0121] It is presumed that the cracks 14 themselves cannot be confirmed as described above because the width of the cracks 14 is smaller than the wavelength of the light I1 as the illumination light. Figure 11 and Figure 12 are SEM (Scanning Electron Microscope) images of the modification regions 12 and the cracks 14 formed inside the semiconductor substrate 21 that is a silicon substrate. Figure 11 (b) of Fig. 5 is an enlarged image of the region Al shown in Figure 11 (a) of Fig. 5, Figure 12 (a) of Fig. 6 is an enlarged image of the region A2 shown in Figure 11 (b) of Fig. 6, Figure 12 (b) of Fig. 7 is an enlarged image of the region A3 shown in Figure 12The magnified image of region A3 shown in (a). Thus, the width of the crack 14 is about 120 nm, which is smaller than the wavelength of light I1 in the near-infrared region (e.g., 1.1–1.2 μm).

[0122] The camera principle envisioned based on the above is as follows. Figure 13 As shown in (a), if the focal point F is placed in the air, light I1 will not return, thus resulting in a completely black image. Figure 13 (The image to the right of (a)). Figure 13 As shown in (b), if the focal point F is located inside the semiconductor substrate 21, the light I1 reflected by the surface 21a will return, thus obtaining a clean image. Figure 13 (Image to the right of (b)). Figure 13 As shown in (c), if the focal point F is aligned with the modified region 12 from the back side 21b, a portion of the light I1 reflected back from the surface 21a will be absorbed and scattered due to the modified region 12, thus obtaining an image in which the modified region 12 appears as a solid black background. Figure 13 (Image to the right of (c)).

[0123] like Figure 14 As shown in (a) and (b), if the focal point F is aligned with the front end 14e of the crack 14 from the back side 21b, then, for example, due to optical specificities (stress concentration, distortion, atomic density discontinuity, etc.) generated near the front end 14e, and the blocking of light generated near the front end 14e, a portion of the light I1 reflected back from the surface 21a will undergo scattering, reflection, interference, absorption, etc., thus obtaining an image in which the black front end 14e is displayed against a clean white background. Figure 14 (Images to the right of (a) and (b)). Figure 14 As shown in (c), if the focal point F is aligned with the portion of the crack 14 other than the front end 14e from the back side 21b, at least a portion of the light I1 reflected by the surface 21a will be reflected back, thus obtaining a clean image. Figure 14 (Image to the right of (c)).

[0124] [Inspection principle of the camera unit]

[0125] The control unit 10, under the condition that the cracks 14 spanning the two rows of modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21, causes the laser irradiation unit 3 to irradiate with laser L. As a result, as expected, when the cracks 14 spanning the two rows of modified regions 12a and 12b reach the surface 21a, the state of the leading edge 14e of the cracks 14 is as described below. That is, as... Figure 15As shown, in the region between the modification region 12a and the surface 21a, and in the region between the modification region 12a and the modification region 12b, the front end 14e of the crack 14 does not occur. The position of the front end 14e of the crack 14 extending from the modification region 12b toward the back surface 21b side (hereinafter, simply referred to as "front end position") is located on the back surface 21b side with respect to the reference position P between the modification region 12b and the back surface 21b.

[0126] In contrast, in the case where the crack 14 that crosses the two modification regions 12a, 12b does not reach the surface 21a, the state of the front end 14e of the crack 14 is as described below. That is, as shown in FIG. 6, in the region between the modification region 12a and the surface 21a, the front end 14e of the crack 14a extending from the modification region 12a toward the surface 21a side does not occur. In the region between the modification region 12a and the modification region 12b, the front end 14e of the crack 14b extending from the modification region 12a toward the back surface 21b side and the front end 14e of the crack 14c extending from the modification region 12b toward the surface 21a side occur. The front end position of the crack 14 extending from the modification region 12b toward the back surface 21b side is located on the surface 21a side with respect to the reference position P between the modification region 12b and the back surface 21b. Figure 16 As shown, in the region between the modification region 12a and the surface 21a, the front end 14e of the crack 14a extending from the modification region 12a toward the surface 21a side occurs. In the region between the modification region 12a and the modification region 12b, the front end 14e of the crack 14b extending from the modification region 12a toward the back surface 21b side and the front end 14e of the crack 14c extending from the modification region 12b toward the surface 21a side occur. The front end position of the crack 14 extending from the modification region 12b toward the back surface 21b side is located on the surface 21a side with respect to the reference position P between the modification region 12b and the back surface 21b.

[0127] According to the above, if the control section 10 performs at least one of the following 1st check, 2nd check, 3rd check, and 4th check, it is possible to evaluate whether or not the crack 14 that crosses the two modification regions 12a, 12b reaches the surface 21a of the semiconductor substrate 21. The 1st check is a check of whether or not the front end 14e of the crack 14a extending from the modification region 12a toward the surface 21a side exists in the region between the modification region 12a and the surface 21a. The 2nd check is a check of whether or not the front end 14e of the crack 14b extending from the modification region 12a toward the back surface 21b side exists in the region between the modification region 12a and the modification region 12b. The 3rd check is a check of whether or not the front end 14e of the crack 14c extending from the modification region 12b toward the surface 21a side exists in the region between the modification region 12a and the modification region 12b. The 4th check is a check of whether or not the front end position of the crack 14 extending from the modification region 12b toward the back surface 21b side is located in the region R3 extending from the reference position P toward the back surface 21b side and not reaching the back surface 21b.

[0128] The 2nd check is a check of whether or not the front end 14e of the crack 14b extending from the modification region 12a toward the back surface 21b side exists in the region between the modification region 12a and the modification region 12b. The 3rd check is a check of whether or not the front end 14e of the crack 14c extending from the modification region 12b toward the surface 21a side exists in the region between the modification region 12a and the modification region 12b. The 4th check is a check of whether or not the front end position of the crack 14 extending from the modification region 12b toward the back surface 21b side is located in the region R3 extending from the reference position P toward the back surface 21b side and not reaching the back surface 21b.

[0129] In addition, according to the above inspection, information indicating the formation state of the modified region and the cracks can be obtained in addition to whether or not the leading end 14e of the crack 14 exists in the prescribed region, the positions of the respective leading ends 14e, the positions of the modified regions 12a, 12b, the lengths of the cracks 14a to 14d, the length of the entire crack 14, and the like. As described above, the cracks 14b, 14d are first cracks extending toward the back surface 21b side as the first surface, and their leading ends 14e are first ends that are the leading ends on the back surface 21b side as the first crack. In particular, the crack 14d is an upper crack. In addition, the cracks 14a, 14c are second cracks extending toward the surface 21a side as the second surface, and their leading ends 14e are second ends that are the leading ends on the surface 21a side as the second crack. In particular, the crack 14a is a lower crack.

[0130] [Method of obtaining formation state]

[0131] Next, a method for obtaining information indicating the formation state of the modified region and the cracks will be described. Figure 17 is a cross-sectional view of an object of the method of obtaining the formation state. In Figure 17 , the functional element layer 22 of the wafer 20 is omitted. In addition, in Figure 17 , the virtual images 12al, 12bl, 14al, 14bl, 14cl, and 14dl of the positions symmetric with respect to the surface 21a are illustrated for the modified region 12a, the modified region 12b, the crack 14a, the crack 14b, the crack 14d, the crack 14c, and the crack 14d, respectively.

[0132] Further, in Figure 17 , the modified regions 12a, 12b extending in one direction are illustrated. As described above, the modified regions 12a, 12b each include a collection of modified points 12s. Therefore, the cracks 14a to 14d extending from the modified regions 12a, 12b are also cracks 14a to 14d extending from the modified points 12s. In particular, in a cross section intersecting the extending direction of the modified regions 12a, 12b, the modified regions 12a, 12b are each identical to a single modified point 12s. Therefore, the modified regions 12a, 12b can be interpreted as the modified points 12s.

[0133] In the wafer 20, the modified regions 12a, 12b, the crack 14a (lower crack) extending from the modified region 12a toward the surface 21a side, the crack 14b extending from the modified region 12a toward the back surface 21b side, the crack 14c extending from the modified region 12b toward the surface 21a side, and the crack 14d (upper crack) extending from the modified region 12b toward the back surface 21b side are formed in a manner not reaching the outer surface (the surface 21a, the back surface 21b).

[0134] In addition, in Figure 17In the example of FIG. 1, the cracks 14b and 14c are connected to each other to form a single crack, but the cracks 14b and 14c can be separated from each other. In addition, there are cases in which the front end 14e on the back surface 21b side of the crack 14d (upper crack) is referred to as a first end (upper crack front end) 14de, and the front end 14e on the surface 21a side of the crack 14a (lower crack) is referred to as a second end (lower crack front end) 14ae.

[0135] The formation state of the modification regions 12a and 12b and the cracks 14a to 14d includes a plurality of items. One example of the items included in the formation state (hereinafter referred to as formation state items) is described below. In addition, the Z direction below is one example of a first direction intersecting (orthogonal to) the surface 21a and the back surface 21b. In addition, in each of the formation state items below, a symbol not shown is added for the sake of simplification of the explanation. In addition, each value is a value with the surface 21a as a reference position (0 point).

[0136] Upper crack front end position F1: the position of the first end 14de with respect to the Z direction.

[0137] Upper crack amount F2: the length of the crack 14d in the Z direction.

[0138] Lower crack front end position F3: the position of the second end 14ae with respect to the Z direction.

[0139] Lower crack amount F4: the length of the crack 14a in the Z direction.

[0140] Total crack amount F5: the total amount of the lengths of the cracks 14a to 14d in the Z direction, that is, the distance between the first end 14de and the second end 14ae with respect to the Z direction.

[0141] Upper and lower crack front end position deviation width F6: the deviation width of the position of the first end 14de and the position of the second end 14ae with respect to a direction (Y direction) intersecting (orthogonal to) the machining travel direction (X direction).

[0142] Presence or absence of modification region marks F7: the presence or absence of marks of modification points constituting each of the modification regions 12a and 12b.

[0143] Amount of meandering of lower crack front end F8: the amount of meandering of the second end 14ae in the Y direction.

[0144] F9: presence or absence of a black streak in a region between the modified region 12a and the modified region 12b, of the leading end on the back surface 21b side of the crack 14b and the leading end on the surface 21a side of the crack 14c (whether the crack 14b and the crack 14c are connected). A black streak is observed in the case where the leading ends of the cracks 14b, 14c are present (corresponding to "black streak is present"), and no black streak is observed in the case where the leading ends of the cracks 14b, 14c are not present (corresponding to "black streak is not present").

[0145] In order to obtain the formation state including the above formation state items, the following imaging C1 to C11 is performed by the light I1 of the imaging unit 4.

[0146] Imaging C1: the semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F of the objective lens 43 of the imaging unit 4 is aligned with the 1st end 14de of the crack 14d. At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is obtained as the position P1.

[0147] Imaging C2: the semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F is aligned with the leading end on the back surface 21b side of the modified region 12b. At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is obtained as the position P2.

[0148] Imaging C3: the semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F is aligned with the leading end on the back surface 21b side of the crack 14b. At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is obtained as the position P3.

[0149] Imaging C4: the semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F is aligned with the leading end on the back surface 21b side of the modified region 12a. At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is obtained as the position P4.

[0150] Imaging C5: the semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F is aligned with the 2nd end 14ae of the crack 14a from the surface 21a side (in such a manner that the focal point F is aligned with the leading end of the virtual image 14aI). At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is obtained as the position P5I. The position P5I is a position corresponding to the leading end of the virtual image 14aI, and is thus a position outside the semiconductor substrate 21 (on the lower side than the surface 21a). In addition, the position P5 of the 2nd end 14ae of the crack 14a (the real image) is obtained by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P5I.

[0151] Imaging C6: The semiconductor substrate 21 is imaged by the light I1 in a manner such that the focal point F is aligned with the front end of the surface 21a side of the modified region 12a from the surface 21a side (in a manner such that the focal point F is aligned with the front end of the virtual image 12aI). At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is acquired as the position P6I. The position P6I is a position corresponding to the front end of the virtual image 12aI, and is thus a position outside the semiconductor substrate 21 (on the lower side than the surface 21a). In addition, the position P6 of the front end of the modified region 12a (real image) is acquired by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P6I. In addition, the position P6 can also be acquired by multiplying the Z height, which is the amount of movement in the Z direction of the objective lens 43 when the modified region 12a is formed, by the DZ rate, which is a coefficient for taking into account the refractive index of the material (for example, silicon) of the semiconductor substrate 21.

[0152] Imaging C7: The semiconductor substrate 21 is imaged by the light I1 while scanning the focal point F in the range P7 between the position P1 and the position P2.

[0153] Imaging C8: The semiconductor substrate 21 is imaged by the light I1 while scanning the focal point F in the range P8 between the position P5 and the position P6.

[0154] Imaging C9: The semiconductor substrate 21 is imaged by the light I1 while scanning the focal point F in the range P9 between the modified region 12a and the modified region 12b.

[0155] Imaging C10: The semiconductor substrate 21 is imaged by the light I1 while scanning the focal point F in the range P10 that straddles the front end of the back surface 21b side of the modified region 12a.

[0156] Imaging C11: The semiconductor substrate 21 is imaged by the light I1 in a manner such that the focal point F is aligned with the front end of the surface 21a side of the modified region 12b from the surface 21a side (in a manner such that the focal point F is aligned with the front end of the virtual image 12bI). At this time, the position in the Z direction in which the focal point F is aligned (the position with the back surface 21b as a reference) is acquired as the position P11I. The position P11I is a position corresponding to the front end of the virtual image 12bI, and is thus a position outside the semiconductor substrate 21 (on the lower side than the surface 21a). In addition, the position P11 of the front end of the modified region 12b (real image) is acquired by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P11I. In addition, the position P11 can also be acquired by multiplying the Z height, which is the amount of movement in the Z direction of the objective lens 43 when the modified region 12b is formed, by the DZ rate, which is a coefficient for taking into account the refractive index of the material (for example, silicon) of the semiconductor substrate 21.

[0157] Each of the above-mentioned formation state items is obtained by performing the above photographing C1 to C10 as described below.

[0158] Upper crack front position F1: Obtained as a value (T-P1) obtained by subtracting the distance of position P1 from the thickness T of the semiconductor substrate 21 from the distance of the back surface 21b.

[0159] Upper crack amount F2: Obtained as a value (P2-P1) obtained by subtracting the distance of position P1 from the back surface 21b from the distance of position P2 from the back surface 21b.

[0160] Lower crack front position F3: Obtained as a value (P5I-T=P5) obtained by subtracting the thickness T of the semiconductor substrate 21 from the distance of position P5I from the back surface 21b as described above.

[0161] Lower crack amount F4: Obtained as a value (P5-P6) obtained by subtracting a value (P6I-T=P6) obtained by subtracting the thickness T of the semiconductor substrate 21 from the distance of position P6I from the back surface 21b from position P5 as described above.

[0162] Total crack amount F5: Obtained as a distance of a value (P5-P1) obtained by subtracting the distance of position P1 from the back surface 21b from the distance of position P5 from the back surface 21b.

[0163] Upper and lower crack front position deviation width F6: Can be measured from the image obtained at range P10 by photographing C10.

[0164] Presence or absence of modification region scratch F7: For the modification region 12b, can be determined from the image obtained at position P2 by photographing C2 or the image obtained at position P11 (position P11I) by photographing C11, and for the modification region 12a, can be determined from the image obtained at position P4 by photographing C4 or the image obtained at position P6 (position P6I) by photographing C6.

[0165] Amount of meandering of lower crack front F8: Can be measured from the image obtained at position P5 (position P5I) by photographing C5.

[0166] Presence or absence of black stripe between modification regions F9: Can be determined from the image obtained at range P9 by photographing C9 (in the case where the front ends of cracks 14b, 14c are confirmed in the image obtained at range P9, it can be determined that "a black stripe is present").

[0167] [Relationship between irradiation conditions and formation state]

[0168] When the modified regions 12a, 12b are formed, if the irradiation conditions of the laser L are changed, the formation states of the modified regions 12a, 12b and the cracks 14a to 14d can also change. Next, the correlation between the irradiation conditions of the laser L and the formation states of the modified regions 12a, 12b and the cracks 14a to 14d will be described, taking the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 in the formation state items as examples.

[0169] First, the irradiation conditions of the laser L for forming the modified regions 12a, 12b include a plurality of items. One example of the items included in the irradiation conditions (hereinafter referred to as "irradiation condition items") is as follows. In addition, in each of the irradiation condition items below, for the sake of simplicity of the description, a not-illustrated symbol is attached.

[0170] Modified region interval Dl: interval of the modified region 12a and the modified region 12b in the Z direction.

[0171] Pulse width D2: pulse width of the laser L.

[0172] Pulse energy D3: pulse energy of the laser L.

[0173] Pulse interval D4: pulse interval of the laser L.

[0174] Condensing state D5: condensing state of the laser, i.e., as one example, the spherical aberration correction level D6, the coma correction level D7, the LBA offset amount D8 (described below).

[0175] Figure 18 and Figure 19 is a graph showing the change in the crack amount when the modified region interval is changed at three points. Figure 18 The horizontal axis of the coordinate graph of (a), (b) of is a graph in which the modified region interval Dl is represented by the Z height. The three points of the modified region interval Dl are level 4, level 8, and level 12, and each corresponds to Figure 19 (a), (b), and (c) of. In addition, Figure 19 is a cut surface.

[0176] As shown in Figure 18 and Figure 19 , in the machining of either of the forward pass and the return pass, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also increase in correspondence with an increase in the modified region interval Dl. In addition, as one example, a case in which the condensing point of the laser L is advanced in the X positive direction (the machining advance direction is the X positive direction) is referred to as machining in the forward pass, and a case in which the condensing point of the laser L is advanced in the X negative direction (the machining advance direction is the X negative direction) is referred to as machining in the return pass.

[0177] Figure 20 and Figure 21is a graph showing changes in the crack amount in the case where the pulse width of the laser light is changed at 3 points. The 3 points of the pulse width D2 are Level 2, Level 3, and Level 5, and each corresponds to (a), (b), and (c) of Figure 21 , respectively. In addition, Figure 21 is a cut surface. As shown in Figure 20 , 21 , in correspondence with an increase in the pulse width D2, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also increase. However, with respect to the total crack amount F5, in the case where the pulse width D2 is Level 2, a black stripe (black stripe between the modified regions) is generated between the modified region 12a and the modified region 12b, and the total crack amount F5 cannot be measured by the imaging unit 4 (the total crack amount F5 is located in the region A according to observation of the cut surface).

[0178] Figure 22 , and Figure 23 is a graph showing changes in the crack amount in the case where the pulse energy of the laser light is changed at 3 points. The 3 points of the pulse energy D3 are Level 2, Level 7, and Level 12, and each corresponds to (a), (b), and (c) of Figure 23 , respectively. In addition, Figure 23 is a cut surface. As shown in Figure 22 , 23 , in correspondence with an increase in the pulse energy D3, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also increase.

[0179] Figure 24 , and Figure 25 is a graph showing changes in the crack amount in the case where the pulse interval of the laser light is changed at 4 points. The 4 points of the pulse interval D4 are Level 2.5, Level 3.3, Level 4.1, and Level 6.7, and each corresponds to (a), (b), (c), and (d) of Figure 24 , respectively. In addition, Figure 25 is a cut surface. As shown in Figure 24 , and Figure 25 , in correspondence with changes in the pulse interval D4, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also change.

[0180] In particular, in the lower crack amount F4 on the way and the return, the upper crack amount F2 on the return, and the total crack amount F5 on the return, a peak appears in the pulse interval D4 of the 4 points. However, with respect to the total crack amount F5, in the case where the pulse interval D4 is Level 6.7, a black stripe (black stripe between the modified regions) is generated between the modified region 12a and the modified region 12b, and the total crack amount F5 cannot be measured by the imaging unit 4 (the total crack amount F5 is located in the region B according to observation of the cut surface).

[0181] Figure 26 , and Figure 27This graph shows the change in cracking amount when the laser focusing state (spherical aberration correction level) is varied at three points. The three points of spherical aberration correction level D6 are level -4, level -10, and level -16, each corresponding to... Figure 27 (a), (b), and (d). Additionally, Figure 27 It is the cut surface. For example... Figure 26 and Figure 27 As shown, corresponding to the increase of the spherical aberration correction level D6, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 decrease.

[0182] Figure 28 and Figure 29 This graph shows the change in cracking amount when the laser focusing state (astigmatism correction level) is varied at three points. The three points for astigmatism correction level D7 are levels 2.5, 10, and 17.5, each corresponding to... Figure 28 (a), (b), and (d). Additionally, Figure 29 It is the cut surface. For example... Figure 28 and Figure 29 As shown, corresponding to the change in astigmatism correction level D7, the upper crack amount F2, lower crack amount F4, and total crack amount F5 also change. In particular, except for the upper crack amount F2 on the outgoing and returning paths, it shows a peak in the astigmatism correction level D7 at 3 points.

[0183] Figure 30 and Figure 31 This graph shows the change in the presence or absence of black stripes when the laser pulse spacing is varied at four points. The four points of the pulse spacing D4 are levels 2.5, 3.3, 4.1, and 6.7, and each corresponds to... Figure 30 and 31 (a), (b), (c), and (d). Additionally, Figure 31 It is the cut surface. For example... Figure 30 As shown, when the pulse spacing D4 is at level 6.7, the leading edges of cracks 14b and 14c can be identified (refer to...). Figure 30 (d)). In fact, as Figure 31 As shown in (d), black stripes Bs were confirmed to be generated between modified regions 12a and 12b in the cross-section.

[0184] As described above, there is a correlation between the irradiation conditions of laser L and the formation state of the modified regions 12a and 12b and the cracks 14a to 14d. Therefore, after the formation of the modified regions 12a and 12b, by capturing images of each item of the formation state by the imaging unit 4, it is possible to determine whether the irradiation conditions of laser L are qualified or to derive the preferred irradiation conditions of laser L.

[0185] [Reference Implementation of Laser Processing Apparatus]

[0186] Next, a reference method for the laser processing apparatus 1 will be explained. Here, an example of the operation for determining whether the irradiation conditions of the laser L are qualified will be explained. Figure 32 This is a flowchart illustrating the main steps of the method for determining whether a result is acceptable. The following method is a reference method for laser processing. Here, firstly, the control unit 10 of the laser processing apparatus 1 receives input from the user (step S1). Step S1 will be explained in more detail.

[0187] Figure 33 It means Figure 1 A diagram showing an example of an input reception area. (See diagram for example.) Figure 33 As shown in (a), in process S1, firstly, the control unit 10 displays information H1, which encourages the user to select whether to perform a machine defect / wafer correction inspection, and information H2, which encourages the user to select the inspection content, through the control input receiving unit 103. The machine defect / wafer correction inspection refers to a process where the irradiation conditions of the laser L used to achieve the desired formation state of the modified regions 12a, 12b, and cracks 14a-14d may differ depending on the machine defect of the laser processing apparatus 1 and the wafer. Therefore, the laser L is irradiated (processed) under specified irradiation conditions, and the pass / fail status of the irradiation conditions is determined. Alternatively, in the following cases, the formation state of the modified regions 12a, 12b, and cracks 14a-14d may be simply referred to as the "formation state," and the irradiation conditions of the laser L may be simply referred to as the "irradiation conditions."

[0188] Additionally, information H2, used to facilitate the selection of inspection content, such as Figure 33 As shown in (b), multiple inspection items H21 to H24 are displayed, grouped by processing position, processing conditions, and wafer thickness. The processing position is the position from the incident surface of laser L (in this case, the back surface 21b) to the front end of the surface 21a side of the modified region 12a. The processing conditions here refer to various conditions under the specified wafer thickness and processing position to prevent cracks from reaching the outer surface (ST).

[0189] Next, in process S1, the input receiving unit 103 accepts the user's selection of whether to perform machine defect / wafer correction inspection. Additionally, in process S1, the input receiving unit 103 accepts the selection of inspection contents H21 to H24, etc. Next, in process S1, when the input receiving unit 103 accepts the selection to perform machine defect / wafer correction inspection and accepts the selection of inspection contents H21 to H24, the control unit 10 sets the processing conditions (including laser L irradiation conditions) corresponding to the inspection contents H21 to H24, etc., as basic processing conditions.

[0190] Figure 34is a view of the input accepting section showing a state of an example of basic processing conditions. As shown in Figure 34 In the process S1, the control section 10 displays information H3 showing the set basic processing conditions in the input accepting section 103, in a case where the input accepting section 103 accepts the selection of performing the machine difference / wafer correction inspection, and accepts the selection of the inspection contents H21 to H24 and the like. The information H3 showing the basic processing conditions includes a plurality of items.

[0191] Among the plurality of items, the item H31 of performing the machine difference / wafer correction inspection, the processing condition H32, the wafer thickness H33, and the processing position H34 are items showing the selection results of the inspection contents H21 to H24 and the like, and are not items accepting the selection from the user at the current point of time. On the other hand, the focal point number H41, the channel number H42, the processing speed H43, the pulse width H44, the frequency H45, the pulse energy H46, the determination item H47, the target value H48, and the specification H49 are items accepting the selection (change) from the user at the current point of time, although they are items of which one example is prompted by the control section 10 as the basic processing conditions.

[0192] Further, the focal point number H41 indicates the number of branches (the number of focal points) of the laser L, the channel number H42 indicates the number of times of scanning the laser L along the line, and the processing speed H43 indicates the relative speed of the condensing point of the laser L. Therefore, the pulse pitch of the laser L can be specified by the processing speed H43 and the (repetition) frequency H45 of the laser L. On the other hand, the determination item H47 indicates the formation state item for the pass / fail determination of the irradiation condition of the laser L among the plurality of formation state items described above.

[0193] Here, as the determination item H47, as one example, the crack amount (lower side), that is, the lower crack amount F4 is set (other formation state items can also be selected). Further, the target value H48 indicates the central value of the pass range of the irradiation condition of the laser L, and the specification H49 indicates the upper and lower width from the central value (the target value H48) of the pass range. That is, here, as the basic processing conditions, in a case where the lower crack amount F4 is in the range of 35 μm or more and 45 μm or less, the target value H48 and the specification H49 are set in such a manner that the irradiation condition of the laser L is determined to be passed (other ranges can also be selected).

[0194] The above is the process S1, and the basic machining conditions for laser machining are set. In the following process, the control section 10 performs a process of determining whether the irradiation conditions set in the process S1, that is, the basic machining conditions, are actually the conditions in which the cracks 14a, 14d do not reach the outer surfaces (the front surface 21a and the back surface 21b), that is, the non-reach conditions (ST conditions) (process S2). Here, the control section 10 (without performing imaging) refers to the database to determine whether the input conditions are the non-reach conditions. As one example, the control section 10 can determine whether it is the condition in which the cracks 14a do not reach the front surface 21a because the focal positions corresponding to the machining positions for which the input conditions are accepted are too close to the front surface 21a (BHC conditions), and the like.

[0195] In the following process, in the case where the result of the determination in the process S2 is a result indicating that the basic machining conditions are the non-reach conditions (process S2: Yes), machining is performed with the basic machining conditions set in the process S1 (process S3). Here, the control section 10 performs a process (machining process) of forming the modification regions 12a, 12b and the cracks 14a to 14d extending from the modification regions 12a, 12b in the semiconductor substrate 21 in such a manner that the modification regions 12a, 12b and the cracks 14a to 14d do not reach the outer surfaces (the front surface 21a and the back surface 21b) of the semiconductor substrate 21 by controlling the laser irradiation unit 3 to irradiate the laser L on the semiconductor substrate 21. More specifically, in this process S3, the control section 10 controls the laser irradiation unit 3 and the stage 2 to form the modification regions 12a, 12b and the cracks 14a to 14d in the inside of the semiconductor substrate 21 by relatively moving the focal points Ol, 02 of the laser L in the X direction in a state where the focal points Ol, 02 are located in the inside of the semiconductor substrate 21. In addition, in the case where the result of the determination in the process S2 is a result indicating that the basic machining conditions are not the non-reach conditions (process S2: No), the process returns to the process S1 to re-set the irradiation conditions.

[0196] Next, the control section 10 performs a process of acquiring information indicating the formation state of the modification regions 12a, 12b and / or the cracks 14a to 14b by controlling the imaging unit 4 to perform imaging on the semiconductor substrate 21 with respect to the light II that has a transmittance with respect to the semiconductor substrate 21 (process S4). Here, in the process S1, the lower crack amount F4 is specified as the determination item H47, and thus at least the imaging C5 and the imaging C6 necessary to acquire the lower crack amount F4 are performed (other imaging can also be performed).

[0197] Next, the control section 10 performs a process of associating and displaying, by controlling the input accepting section 103, information indicating the irradiation condition of the laser L in the process S3 with information indicating the formation state acquired in the process S4 with each other on the input accepting section 103 (process S5). The information indicating the formation state (formation state item) displayed in the process S5 is the amount of undercracking F4 of the determination item H47 set in the process S1 (other formation state items can be displayed together). As described above, the determination item H47 can be selected.

[0198] Therefore, in the process S1, the control section 10 performs a process of displaying, by controlling the input accepting section 103, information for facilitating selection of the formation state item displayed on the input accepting section 103 in the process S5 among a plurality of formation state items on the input accepting section 103. Further, the input accepting section 103 accepts selection of the formation state item in the process S1. Next, in the process S5, the control section 10 displays, by controlling the input accepting section 103, information indicating the formation state item (in this case, the amount of undercracking F4) accepted by the input accepting section 103 in association with information indicating the irradiation condition (in this case, the pulse energy D3) of the laser L on the input accepting section 103.

[0199] Further, the control section 10 can also perform a process of displaying, by controlling the input accepting section 103, information for facilitating selection of the irradiation condition item displayed on the input accepting section 103 in the process S5 among a plurality of irradiation condition items included as the irradiation condition of the laser L on the input accepting section 103. In the case where this process is performed, the input accepting section 103 can also accept input of selection of the irradiation condition item, and the control section 10 displays, by controlling the input accepting section 103, information indicating the irradiation condition item accepted by the input accepting section 103 in association with information indicating the formation state on the input accepting section 103.

[0200] In the next process, the control section 10 performs a process of determining whether or not the irradiation condition of the laser L in the process S3 is qualified based on the information indicating the formation state of the modified region 12a, 12b and / or the crack 14a to 14b acquired in the process S4 (process S6). More specifically, in the case where the amount of undercracking F4 acquired by the process S4 is in the range of 35 μm or more and 45 μm or less, the control section 10 determines that the irradiation condition of the laser L in the process S3 is qualified, because the determination item H47 set in the process S1 is the amount of undercracking F4, and the target value H48 is 40 μm, and the specification is ±5 μm.

[0201] As described above, the determination item H47 can be selected. Therefore, in the step S1, the control section 10 executes the process of displaying, on the input accepting section 103, information for facilitating selection of the determination item H47 used for promoting determination of the items for pass / fail judgment among the plurality of formation state items included in the formation state, by controlling the input accepting section 103. Further, the input accepting section 103 accepts selection of the determination item H47 in the step S1. Next, the control section 10 performs pass / fail judgment based on the information indicating the determination item H47 accepted by the input accepting section 103.

[0202] Further, as described above, the target value H48 and the specification H49 can be selected. Therefore, in the step S1, the control section 10 executes the process of displaying, on the input accepting section 103, information for facilitating input of the target value H48 and the specification H49 of the formation state, by controlling the input accepting section 103. Further, the input accepting section 103 accepts input of the target value H48 and the specification H49 in the step S1. Further, the control section 10 performs pass / fail judgment by comparing the formation state (the amount of subsurface cracks F4) under the irradiation condition in the step S3 with the target value H48 and the specification H49 in the step S6.

[0203] In the case where the result of the step S6 is a result indicating pass (step S6: Yes), the control section 10 performs determination of whether or not to end the pass / fail judgment (step S8) after executing the process of displaying, on the input accepting section 103, a determination result (a result of the pass / fail judgment) indicating pass, by controlling the input accepting section 103 (step S7). In this step S8, the control section 10 displays, on the input accepting section 103, information for facilitating selection of whether or not to end the pass / fail judgment, by controlling the input accepting section 103, and ends the process in the case where the input accepting section 103 accepts input of ending the pass / fail judgment (step S8: Yes). On the other hand, in this step S8, in the case where the input accepting section 103 accepts input of not ending the pass / fail judgment but performing re-determination (step S8: No), the process shifts to the step S10 described below. This is because, even in the case where the determination result of the control section 10 is pass, there is a case where, for example, there is a request to set a good condition further away from failure and continue the pass / fail judgment.

[0204] On the other hand, in the case where the result of the step S6 is a result indicating failure (step S6: No), the control section 10 executes the process of displaying, on the input accepting section 103, a determination result (a result of the pass / fail judgment) indicating failure, by controlling the input accepting section 103 (step S9), and performs re-determination of the process after the plurality of irradiation condition items are modified as the modification items and the processing is performed again.

[0205] The re-determination will be described in more detail. In a case where the result of the eligibility determination in Step S6 is not eligible, and in a case where the input of performing the re-determination is received in Step S8, the control section 10 performs the re-determination by controlling the input receiving section 103 to correct at least one of the plurality of irradiation condition items included in the irradiation condition as a correction item, and to perform the processing after the processing of performing the machining process again. That is, as the case of performing the re-determination, it is not limited to the case where the result of the eligibility determination is not eligible. In other words, in this case, the re-determination is performed in correspondence with the result of the eligibility determination in Step S6. Further, the input receiving section 103 can be caused to display information that promotes selection of whether to perform the re-determination, and the re-determination is performed in a case where the input receiving section 103 receives the selection of performing the re-determination.

[0206] Accordingly, the control section 10 first performs a process of causing the input receiving section 103 to display information that promotes selection of the correction item H5 to the input receiving section 103 by controlling the input receiving section 103 (Step S10), as shown in FIG. 10. The correction item H5 can be selected, for example, from the irradiation condition items described above. Further, the control section 10 can cause the input receiving section 103 to display information that promotes selection of the determination item H47 and the machining condition H32 to the input receiving section 103 at the same time as the correction item H5. Then, the input receiving section 103 receives at least the selection of the correction item H5 by the user (Step S10). Figure 35

[0207] Next, the control section 10 causes the input receiving section 103 to display the correction item H5, which is the result of the selection received by the input receiving section 103, as the setting screen H6 of the variable condition to the input receiving section 103 by controlling the input receiving section 103, as shown in FIG. 11. The setting screen H6 is, as one example, a screen in a case where the pulse energy D3 is selected as the correction item H5. Accordingly, as the variable condition, the pulse energy H46 is displayed. Here, the value of the basic machining condition is displayed as the pulse energy H46, the range of the level 2 is displayed as the variable range H61, and 3 points are displayed as the variable point number H62. These items can also be selected (changed) by the user. Figure 36

[0208] ​​Further, in the setting screen H6, the maximum value is displayed as the adjustment method H63. Therefore, in the following re-determination, irradiation (processing) of the laser L of three different pulse energies D3 within the range of the level 2 is performed, and as a result, in a case where no determination of eligibility is performed among the plurality of pulse energies D3, the pulse energy D3 in which the maximum lower crack amount F4 is obtained is displayed as an adjustment candidate. Further, in the setting screen H6, items other than the correction item H5, the determination item H47, and the wafer thickness H33 can be selected by the user at the current point in time. Then, the control section 10 sets the irradiation conditions and the like displayed in the setting screen H6 as conditions for re-determination. Further, in the adjustment method H63, the minimum value or the average value or the like can be selected instead of the maximum value according to the irradiation conditions.

[0209] Next, the control section 10 performs processing with the conditions displayed in the setting screen H6 (step S11). That is, the control section 10 performs re-determination by correcting the correction item H5 accepted by the input acceptance section 103 from now on. In this step S11, the control section 10 performs processing of forming the modification regions 12a, 12b and the cracks 14a to 14d extending from the modification regions 12a, 12b in the semiconductor substrate 21 by controlling the laser irradiation unit 3 to irradiate the laser L on the semiconductor substrate 21 in such a manner that the outer surfaces (the front surface 21a and the back surface 21b) of the semiconductor substrate 21 are not reached. In particular, in this case, the pulse energy as the correction item H5 is processed for three different cases, respectively.

[0210] Next, the control section 10 performs processing of acquiring information indicating the formation state of the modification regions 12a, 12b and / or the cracks 14a to 14b by controlling the imaging unit 4 to perform imaging on the semiconductor substrate 21 with respect to the light II that is transparent to the semiconductor substrate 21 (step S12). In this case, in the step S1 and the step S10 (setting screen H6), the lower crack amount F4 is specified as the determination item H47, and thus imaging C6 capable of acquiring the lower crack amount F4 is at least performed.

[0211] Next, the control section 10 performs processing of determining whether or not the cracks 14a, 14d do not reach the outer surfaces (the front surface 21a and the back surface 21b) based on the information indicating the formation state acquired in the step S12 (step S13). In this case, in at least one of a case where the second end 14ae of the crack 14a is not confirmed in the image acquired by the imaging C5 and a case where the crack 14d is confirmed on the back surface 21b in the image acquired by the imaging C0, it can be determined that the cracks 14a, 14d reach the outer surfaces, rather than not reach (ST). Further, in the imaging C0, the back surface 21b is imaged by the light II (see FIG. 6). Figure 17

[0212] ​If the determination result of step S13 indicates that the cracks 14a and 14d have reached the outer surface, that is, not that they have not reached the outer surface (step S13: no), then the process is transferred to step S10 by resetting the irradiation conditions in step S10.

[0213] On the other hand, if the determination result of process S13 indicates that cracks 14a and 14d have not reached the outer surface, i.e., not reached (process S13: Yes), the control unit 10 performs a process (process S14) by establishing a correlation between the information indicating the irradiation conditions of laser L in process S11 and the information indicating the formation state obtained in process S12 through the control input receiving unit 103 and displaying it on the input receiving unit 103. The formation state item displayed in this process S14 is the lower crack amount F4 of the determination item H47 set in process S10. As described above, the determination item H47 can be selected.

[0214] Therefore, in process S10, the control unit 10 performs a process by controlling the input receiving unit 103 to display information facilitating the selection of a formation state item among multiple formation state items that will be displayed on the input receiving unit 103 in process S14. Additionally, the input receiving unit 103 accepts the selection of a formation state item in process S10. Next, in process S14, the control unit 10, by controlling the input receiving unit 103, establishes a correlation between information indicating the formation state item accepted by the input receiving unit 103 (here, lower crack amount F4) and information indicating the irradiation conditions of the laser L, and displays this association on the input receiving unit 103.

[0215] In the next process, the control unit 10 performs a process (process S15) to determine whether the laser L irradiation conditions in process S11 are qualified or not, based on the information indicating the formation state obtained in process S12. More specifically, the judgment item H47 set in process S10 is the lower crack amount F4, the target value H48 is 40μm, and the specification is ±5μm. Therefore, if the lower crack amount F4 obtained from process S12 is in the range of 35μm to 45μm, the control unit 10 determines that the laser L irradiation conditions in process S11 are qualified.

[0216] As described above, target value H48 and specification H49 can be selected. Therefore, in process S10, the control unit 10 performs processing by displaying the input information of target value H48 and specification H49 for promoting the formation state through the control input receiving unit 103. In addition, the input receiving unit 103 accepts the input of target value H48 and specification H49 in process S10. Then, in process S15, the control unit 10 determines whether the formation state (lower crack amount F4) under the irradiation conditions in process S11 is qualified or not by comparing it with target value H48 and specification H49.

[0217] After that, in a case where the result of the process S15 is a result indicating acceptance (process S15: Yes), the control section 10 displays the information H7 indicating the determination result on the input accepting section 103 by controlling the input accepting section 103 (process S16), and ends the processing. Figure 37 is a view of the input accepting section indicating the state in which the information indicating the determination result (acceptance) is displayed. As shown in Figure 37 In the information H7 indicating the determination result, in addition to the above-described correction item H5, the determination item H47, and the wafer thickness H33, the machining output H72, the acceptance / non-acceptance determination H73, the adjustment result H74, the internal observation image H75, and the coordinate chart H76 are also displayed.

[0218] The machining output H72 is an item for making the pulse energy D3 as the correction item H5 variable. That is, in this case, the pulse energy D3 is made variable at three points by making the machining output H72 variable at three points. In the adjustment result H74, among the three points of the machining output H72 (pulse energy), the machining output H72 (pulse energy) at which the amount of subsurface cracks F4 is the largest (supposed to be displayed as a peak value) is displayed.

[0219] In addition, the pulse energy D3 as the irradiation condition item can be made variable by the machining output as described above. The machining output can be adjusted, for example, by adjustment of an attenuator or the like, or the original output · frequency of the laser irradiation unit 3. On the other hand, for example, in a case where the condensing point of the laser L is formed of a plurality of points due to branching of the laser, the machining output can be made variable by controlling the position in the Z direction of the condensing point using the spatial light modulator 5. In addition, in a case where the condensing point of the laser L is single, the machining output can be made variable by adjusting the position in the Z direction of the laser irradiation unit 3 among a plurality of channels.

[0220] In addition, the pulse width D2 can be made variable by setting switching of the laser irradiation unit 3 (combination of the loaded waveform memory · frequency and the original output), or switching of the light source 31 in a case where a plurality of light sources 31 are loaded, or the like. In addition, as the irradiation condition item, a pulse waveform including the pulse width D2 can be set. In this case, the pulse waveform can be made variable in addition to the pulse width D2, such as the waveform shape (rectangular wave, Gaussian, burst pulse), or the like.

[0221] Further, the pulse interval D4 can be made variable by the relative speed of the condensing point of the laser L (the moving speed of the stage 2) or the frequency of the laser L, or the like. Further, the spherical aberration correction level D6 can be made variable by a correction ring lens or a modulation pattern. The astigmatism correction level D7 (or the coma aberration correction level) can be made variable by adjustment of the optical system or a modulation pattern. Further, the LBA offset D8 can be made variable by controlling the spatial light modulator 5.

[0222] Continuing to refer to Figure 37 In the internal observation image H75, an image (image taken by the camera C5) showing the state in which the focal point F is aligned with the 2nd end 14ae (lower crack tip) of the crack 14a (lower crack) of each of the 3 processing outputs H72 (pulse energy D3) is displayed. In the coordinate graph H76, the pulse energy D3 is correlated with the lower crack amount F4. That is, in this case, the control section 10 displays, by the control input accepting section 103, information indicating the formation state item (lower crack amount F4) accepted by the input accepting section 103 in the formation state in association with the correction item H5 (pulse energy D3) in the information indicating the irradiation condition (coordinate graph H76 in which the association is made) in the input accepting section 103.

[0223] Further, in the information H7 indicating the determination result, information H77 promoting selection of whether or not to change the correction item so as to end the adjustment is displayed. Thus, the user can select whether or not to set the correction item (in this case, the pulse energy D3) to the value (pass value) displayed in the adjustment result H74.

[0224] In the next process, the control section 10 determines whether or not to end the pass / fail determination (process S17). In this process S17, the control section 10 displays, by the control input accepting section 103, information promoting selection of whether or not to end the pass / fail determination in the input accepting section 103, and ends the processing in the case where the input accepting section 103 accepts an input to end the pass / fail determination (process S17: YES). On the other hand, in this process S17, in the case where the input accepting section 103 accepts an input to make a re-determination without ending the pass / fail determination (process S17: NO), the processing shifts to the process S10 described below. This is because, even in the case where the re-determination result of the control section 10 is pass, there can be a case where, for example, it is required to set a good condition further away from the fail and continue the pass / fail determination.

[0225] On the other hand, in the case where the result of the process S15 is a result indicating fail (process S15: NO), the control section 10 performs a process of displaying, by the control input accepting section 103, the determination result (result of the pass / fail determination) indicating fail in the input accepting section 103 (process S18), and shifts to the process S10. Figure 38is a diagram showing an input receiving section in a state where information showing a determination result (unqualified) is displayed. As shown in Figure 38 Figure 37 The information H8 showing the determination result is compared with the information H7 shown in Figure 37 and is different in the aspect of being displayed as unqualified in the qualification / unqualification determination H73, in the aspect of being displayed as unadjustable in the adjustment result H74, and in the contents of the coordinate graph H76. In addition, in the information H8 showing the determination result, the information H81 for promoting selection of whether to perform readjustment is displayed. Thereby, the user can avoid the above-described transition to the process S10 and repeated readjustment, and end the processing.

[0226] In the above reference mode, the lower crack amount F4 is exemplified as the formation state item, and the pulse energy D3 is exemplified as the irradiation condition item (modification item). However, as the irradiation condition item (modification item), any of the above-described items can be selected, and as the formation state item, any of the items having a correlation (here, the qualification / unqualification determination for the irradiation condition item can be used) with the selected irradiation condition item (modification item) can be selected.

[0227] For example, even in the case where any of the condensing states D5 from the modified region interval D1 is selected as the irradiation condition item (modification item), the total crack amount F5, the meandering amount F8 of the lower crack front, and the presence / absence F9 of the black stripe between the modified regions can be selected as the formation state item (having a correlation) from the upper crack front position F1. In addition, in the case where the condensing state D5 is selected as the irradiation condition item (modification item), the upper and lower crack front position deviation width F6 and the presence / absence F7 of the modified region marks can be further selected as the formation state item. The same applies to other embodiments with respect to this point.

[0228] [First Embodiment of Laser Processing Apparatus]

[0229] Next, an embodiment of the laser processing apparatus 1 will be described. Here, one example of an operation of deriving the irradiation condition of the laser L (parameter management) will be described. Figure 39 is a flowchart showing main processes of a method of deriving the irradiation condition. The following method is the first embodiment of the laser processing method. Here, first, the control section 10 of the laser processing apparatus 1 receives an input from the user (process S21). The process S21 will be described in more detail.

[0230] As shown in Figure 40As shown in this step S21, first, the control section 10 causes the input accepting section 103 to display the information Jl for facilitating selection by the user of whether or not to execute parameter management, the information J2 for facilitating selection by the user of a variable item, the information J3 for facilitating selection by the user of a determination item, and the information J4 indicating that the selection of the processing condition is automatic, by controlling the input accepting section 103. The parameter management is, for example, a mode for deriving an irradiation condition with respect to an object whose irradiation condition (parameter) for obtaining a desired formation state is unknown.

[0231] Therefore, in the present embodiment, as described below, the laser L is irradiated with different irradiation conditions for each of the plurality of lines 15, and the modified regions 12a, 12b, etc. are formed. The variable item indicates an irradiation condition item that differs for each line 15 among the irradiation conditions. In addition, the determination item is an item that determines (evaluates) the variable item among the formation state items. The processing condition here is a condition in which the crack does not reach the outer surface (ST).

[0232] Next, in the step S21, the input accepting section 103 accepts the selection by the user of whether or not to execute parameter management, the variable item, and the determination item. Next, the control section 10 automatically selects one example of the processing condition in the case where the selection of executing parameter management, the selection of the variable item, and the selection of the determination item are made, and displays information indicating the selected processing condition on the input accepting section 103.

[0233] Figure 41 is a view of the input accepting section indicating the state in which one example of the selected processing condition is displayed. As shown in this view, Figure 41 The information J5 indicating the processing condition is displayed on the input accepting section 103 to prompt the user. The information J5 indicating the processing condition includes a plurality of items. Among the plurality of items, the item J51 indicating execution of parameter management, the variable item J52, and the determination item J53 indicate the results of the previous selections, and not the selections from the user at the current point in time (the same applies to the wafer thickness J54).

[0234] On the other hand, the number of focal points J55, the number of channels J56, the processing speed J57, the pulse width J58, the frequency J59, and the ZH (Z height: processing position in the Z direction) J60, although being one example prompted by the control section 10, accept the selections (changes) from the user. In addition, the meanings of the number of focal points J55 to the frequency J59 are the same as those of the number of focal points H41 to the frequency H45 shown in Figure 32 the view.

[0235] Further, in this example, the pulse energy D3 is selected as a variable item. Therefore, as a variable condition, the pulse energy J61 is displayed. Here, as the pulse energy J61, an initial value is displayed, and as a variable range J62, a range of levels 1 to 12 is displayed. Further, as a variable point number J63, 3 points are displayed. This means that the number of lines 15 having different irradiation conditions is 3. As to these items, selection (change) by the user at the current point of time is also possible.

[0236] In the next process, the 3rd process of determining whether the irradiation condition set in the process S21 is actually a condition in which the cracks 14a, 14d do not reach the outer surface, that is, a non-reach condition (ST condition) is executed (process S22). Here, the control section 10, as in the above process S2, can determine whether the inputted condition is a non-reach condition.

[0237] In the next process, in the case where the result of the determination in the process S22 is a result indicating that the irradiation condition set in the process S21 is a non-reach condition (process S22: Yes), as described above, processing is performed according to the information J5 indicating the processing condition (process S23). That is, here, the control section 10 executes the 1st process of irradiating the laser L to the semiconductor substrate 21 along each of the plurality of lines 15 so as to form the modified region 12a, 12b, etc. in the semiconductor substrate 21 in a manner not reaching the outer surface (the front surface 21a and the back surface 21b) of the semiconductor substrate 21 (process S23, 1st process).

[0238] In particular, in this process S23, as to each of the plurality of lines 15, the laser L is irradiated to the semiconductor substrate 21 by irradiation conditions different from each other. As one example, here, as prompted by the information J5 indicating the processing condition, the pulse energy D3 is changed at 3 points (3 lines 15) between level 1 and level 12 and irradiation of the laser L is performed. Thereby, on each of the lines 15, the modified region 12a, 12b, etc. having different formation states are formed. Further, in the case where the result of the determination in the process S22 is a result indicating that the irradiation condition is not a non-reach condition (process S22: No), the process returns to the process S21 to re-set the irradiation condition.

[0239] Next, the control section 10 executes the 2nd process of acquiring information indicating the formation state of the modified region 12a, 12b and / or the cracks 14a to 14b by controlling the imaging unit 4 to perform imaging of the semiconductor substrate 21 by the light II having transmittance with respect to the semiconductor substrate 21 (process S24, 2nd process). In particular, in this process S24, as to each of the plurality of lines 15, information indicating the formation state is acquired. Here, in the process S21, the lower crack amount F4 is specified as the determination item J53, and thus at least the imaging C5 and the imaging C6 necessary to acquire the lower crack amount F4 are executed (other imaging can also be executed).

[0240] Next, the control section 10 performs a fourth process (step S25) of displaying the information indicating the processing result (information acquired in step S24) on the input accepting section 103 by controlling the input accepting section 103. Figure 42 is a view of the input accepting section indicating the state of displaying the information indicating the processing result. As shown in Figure 42 the information indicating the processing result J7 is displayed in step S25. In the information indicating the processing result J7, in addition to the above-mentioned variable items J52, the determination item J53, and the wafer thickness J54, the pulse energy J72, the result display J73, the internal observation image J74, and the coordinate graph J75 are also displayed.

[0241] The pulse energy J72 is an item indicating the variable value of the pulse energy as the variable item J52. That is, in this case, the pulse energy D3 is made different at three points shown in the drawing. In the internal observation image J74, an image (image acquired by the imaging C5) showing the state in which the focal point F is aligned with the second end 14ae (lower crack tip) of the crack 14a (lower crack) for each of the three processing outputs (pulse energies D3) is displayed.

[0242] In the coordinate graph J75, the relationship between the pulse energy D3 and the lower crack amount F4 is indicated. That is, in this step S25, the control section 10 performs a fourth process of displaying the information indicating the irradiation condition of the laser L in step S23 (first process) and the information indicating the formation state acquired in step S24 (second process) in association with each other (coordinate graph J75 in which the association is established) on the input accepting section 103 by controlling the input accepting section 103.

[0243] In addition, the information indicating the formation state (formation state item) displayed in this step S25 is the lower crack amount F4 which is the determination item J53 set in step S21. As described above, the determination item J53 can be selected. Therefore, in step S21, the control section 10 performs a seventh process of displaying the information promoting the selection of the formation state item among the plurality of formation state items displayed on the input accepting section 103 in step S25 on the input accepting section 103 by controlling the input accepting section 103.

[0244] In addition, the input accepting section 103 accepts the selection of the formation state item in step S21. Next, the control section 10 displays the information indicating the formation state item (in this case, the lower crack amount F4) accepted by the input accepting section 103 in association with the information indicating the irradiation condition of the laser L (in this case, the pulse energy D3) on the input accepting section 103 by controlling the input accepting section 103 in step S25.

[0245] Similarly, in process S21, the control unit 10 executes the sixth process by controlling the input receiving unit 103 to display the selection information of the irradiation condition item displayed in process S25 on the input receiving unit 103, which is one of the multiple irradiation condition items included in the irradiation conditions for promoting laser L, i.e., the variable item selected according to each line 15. In addition, the input receiving unit 103 accepts the input of the selection of the irradiation condition item (variable item), and the control unit 10 executes process S23 by controlling the laser irradiation unit 3 to perform process S23 in a different manner for each line 15 according to the variable item accepted by the input receiving unit 103 (in this case, pulse energy D3), and by controlling the input receiving unit 103, establishes a correlation between the information indicating the variable item accepted by the input receiving unit 103 in the irradiation conditions (in this case, pulse energy D3) and the information indicating the formation state (in this case, lower crack amount F4) and displays it on the input receiving unit 103.

[0246] Specifically, as shown in coordinate diagram J75, the control unit 10 obtains information indicating the irradiation conditions (in this case, pulse energy D3) and information indicating the formation state (in this case, lower crack amount F4) by establishing a correlation between each of the multiple lines 15 through the camera in process S24. Thus, in the laser processing apparatus 1, for example, it is possible to obtain the relationship between irradiation conditions and formation state relative to an unknown object (parameter management is possible). Specifically, as shown in coordinate diagram J75, the control unit 10 obtains information by establishing a correlation between irradiation conditions and formation state (parameter management is possible) for each of the multiple lines 15. Figure 43 As shown, the graph displays a coordinate system with the horizontal axis AX as a variable (parameter) and the vertical axis AY as the formation state under that variable, allowing for visual parameter management. Therefore, users can adjust the irradiation conditions to achieve the desired formation state in the modified regions 12a, 12b, etc.

[0247] In the next process, the control unit 10 displays information J76, prompting the user to choose whether to continue parameter management, on the input reception unit 103. For example... Figure 42 As shown, this information J76 has already been displayed in process S25. Therefore, here, the input receiving department 103 accepts the selection of whether to continue parameter management (process S26). Continuing parameter management means changing variable items or decision items and performing further processing. If the result of process S26 indicates that no further processing is required (process S26: Yes), the processing ends.

[0248] On the other hand, in a case where the result of the process S26 is a result indicating that reworking is required (process S26: No), the control section 10, like in the process S21, causes the input accepting section 103 to display the information J2 for facilitating selection of the variable item, the information J3 for facilitating selection of the determination item, the information J4 indicating that selection of the processing condition is automatic, and the information J5 indicating the processing condition, and accepts the input (process S27). Here, for example, an irradiation condition item different from the variable item selected in the process S21 can be set as the variable item, or a formation state item different from the determination item selected in the process S21 can be set as the determination item.

[0249] Next, the control section 10, in correspondence with the input acceptance in the process S27, causes processing to be performed (process S28) like in the process S23, and causes imaging to be performed (process S29) like in the process S24, thereby acquiring information indicating the formation state of the modified regions 12a, 12b, and the like.

[0250] Next, the control section 10 performs a fifth process of determining whether or not the cracks 14a, 14d have reached the outer surface, based on the information indicating the formation state acquired in the process S29 (process S30). Here, in a case where at least one of the following is true, it can be determined that the cracks 14a, 14d have reached the outer surface, rather than not reached. In a case where the second end 14ae of the crack 14a is not confirmed in the image acquired by the imaging C5, and in a case where the crack 14d is confirmed on the back surface 21b in the image acquired by the imaging C0.

[0251] In a case where the result of the determination in the process S30 is a result indicating that the cracks 14a, 14d have reached the outer surface, i.e., not not reached (process S30: No), the processing is shifted to the process S27. On the other hand, in a case where the result of the determination in the process S30 is a result indicating that the cracks 14a, 14d have not reached the outer surface, i.e., not reached (process S30: Yes), the control section 10, like in the process S25, causes information indicating the processing result to be displayed on the input accepting section 103 (process S31), and determines whether or not reworking is required (process S32). The processing is ended in a case where the result of the process S32 is a result indicating that reworking is not required, and is shifted to the process S27 in a case where the result is a result indicating that reworking is required.

[0252] [Second Embodiment of the Laser Processing Apparatus]

[0253] Next, another embodiment of the laser processing apparatus 1 will be described. In this embodiment, as in the first embodiment, the irradiation conditions of the laser L are derived. However, in this embodiment, the variable item is set to the LBA offset D8 included in the condensing state D5 among the irradiation condition items. First, the LBA offset will be described. As described above, the laser irradiation unit 3 has the spatial light modulator 5 and the condensing lens 33 that condenses the laser L modulated by the spatial light modulator 5. Thus, the modulation pattern displayed on the reflection surface 5a of the spatial light modulator 5 is imaged on the entrance pupil surface 33a of the condensing lens 33.

[0254] The irradiation of the laser L is performed in a state where the center of the modulation pattern is offset with respect to the center of the entrance pupil surface 33a of the condensing lens 33, whereby the formation state of the modified regions 12a, 12b, etc. is changed. In particular, in a state where the center of at least the spherical aberration correction pattern in the modulation pattern is offset with respect to the center of the entrance pupil surface 33a of the condensing lens 33, the formation state can be appropriately controlled. The LBA offset D8 is the amount of offset of the center of such a spherical aberration correction pattern with respect to the center of the entrance pupil surface 33a of the condensing lens 33. In the LBA offset D8, the amount of offset with respect to the X direction is referred to as the X offset, and the amount of offset with respect to the Y direction is referred to as the Y offset. The X direction is the direction of travel of the condensing point of the laser, and is the direction parallel to the laser processing travel direction, and the Y direction is the direction orthogonal to the direction of travel of the condensing point of the laser, and is the direction perpendicular to the laser processing travel direction.

[0255] Figure 44 is a graph showing the relationship between the Y offset and the formation state. In Figure 44 In (a) of FIG. 17, the modified regions 12 and the cracks 14 extending from the modified regions 12 in a case where the Y offset is changed from -2.0 to +2.0 in units of 0.5 are shown. With respect to each Y offset, a pair of modified regions 12 (and the corresponding cracks 14) is shown, but the left side shows the processing in the forward direction (X positive direction), and the right side shows the processing in the return direction (X negative direction). In addition, the Y offset corresponds to the pixel of the spatial light modulator 5. Figure 44 (b) of FIG. 17 is the cut surface after processing in each Y offset. In addition, in the example of Figure 44 The X offset is constant in the example of

[0256] As described above, in the first embodiment, the LBA offset D8 is derived as the variable item. However, the LBA offset D8 is not necessarily derived as the variable item. For example, the LBA offset D8 can be set to a constant value. In this case, the X offset and the Y offset are derived as the variable items. Figure 44As shown, when the modification region 12 and the crack 14 are formed in the semiconductor substrate 21 by irradiating the laser L, if the Y offset amount is changed, the formation state of the modification region 12 and the crack 14 will also change. Therefore, by obtaining the formation state of the modification region 12 and the crack 14, the irradiation condition of the laser L that makes the modification region 12 and the crack 14 into the desired formation state can be derived. In addition, the LBA offset amount D8 is related to all of the above-described upper crack tip position F1 to the presence or absence of the black stripe F9 between the modification regions in the formation state. Hereinafter, the derivation method of the LBA offset amount D8 in the irradiation condition of the laser L will be described.

[0257] Figure 45 and Figure 46 is a flowchart showing the main procedures of the derivation method of the LBA offset amount. The following method is the second embodiment of the laser processing method. As shown in Figure 45 here, first, the control section 10 receives an input from the user (procedure S41). The procedure S41 will be described in more detail. In the procedure S41, first, by controlling the input receiving section 103, information (not shown) for facilitating the user's selection of whether to perform the LBA offset check is displayed on the input receiving section 103. The so-called LBA offset check is a check for deriving the LBA offset amount.

[0258] Next, in the procedure S41, the input receiving section 103 receives the user's selection of whether to perform the LBA offset check. Next, in the procedure S41, when the input receiving section 103 receives a selection of performing the LBA offset check, as shown in Figure 47 , information K1 for facilitating the selection of the check condition is displayed on the input receiving section 103. The information K1 includes a plurality of items. Among the plurality of items, the LBA offset check K2 is an item for facilitating the user's selection of whether to perform a check (derivation) of the X offset amount, a check (derivation) of the Y offset amount, or a check (derivation) of both the X offset amount and the Y offset amount.

[0259] The LBA-X offset K3 indicates the variable range of the X offset amount (e.g., ±6) and can be selected by the user (or can be automatically selected). The LBA-Y offset K4 indicates the variable range of the Y offset amount (e.g., ±2) and can be selected by the user (or can be automatically selected). The determination item K5 indicates the formation state item for deriving the LBA offset amount and can be selected by the user (or can be automatically selected). In addition, the wafer thickness K6 can also be selected by the user (or can be automatically selected).

[0260] Next, in the process S41, the input reception part 103 receives at least the LBA offset check K2 input. Then, the control part 10, in the case where the input reception part 103 receives the input of the LBA offset check K2 (as for the LBA-X offset K3, the LBA-Y offset K4, the determination item K5, and the wafer thickness K6, automatic selection is performed in the absence of the input from the user), causes the input reception part 103 to display the setting screen including the selection result in the input reception part 103 by controlling the input reception part 103.

[0261] Figure 48 is a view of the input reception part indicating the state where the setting screen is displayed. As shown in Figure 48 , the setting screen K7 includes a plurality of items. Among the plurality of items, the LBA offset check K71, the determination item K72, the X offset variable range K73, the Y offset variable range K74, and the wafer thickness K75 indicate the previous selection result, and do not receive the selection from the user at the current point of time. In addition, in the LBA offset check K71, it is indicated that the check (derivation) of both the X offset amount and the Y offset amount is performed in the LBA offset check K71. Figure 47

[0262] On the other hand, the focal point number K81, the channel number K82, the processing speed K83, the pulse width K84, the frequency K85, the ZH (Z height: processing position in the Z direction) K86, and the processing output K87, although they are one example of the control part 10, receive the selection (change) from the user at the current point of time. In addition, the meanings of the focal point number K81 to the frequency K85 are the same as those of the focal point number H41 to the frequency H45 shown in Figure 34 .

[0263] In the following process, the control part 10 performs the third process (process S42) of determining whether the processing condition (irradiation condition) set in the process S41 is actually the condition in which the cracks 14a, 14d do not reach the outer surface (the surface 21a and the back surface 21b), that is, the non-reach condition (ST condition). Here, the control part 10, like the above-described process S2, can determine whether the received input condition is the non-reach condition. The result of the determination of this process S42 is that, in the case where the basic processing condition is not the non-reach condition (process S42: No), the process shifts to the process S41.

[0264] ​On the other hand, in a case where the result of the determination in the step S42 is a result indicating that the basic processing condition is the non-arrival condition (step S42: YES), processing is performed in accordance with the selection contents and the processing condition displayed on the setting screen K7 (step S43, first process). That is, in this case, the control section 10 performs irradiation of the laser L to the semiconductor substrate 21 along each of the plurality of lines 15 to form the modified regions 12a, 12b, and the like on the semiconductor substrate 21 in a manner not reaching the outer surfaces (the front surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0265] In particular, in this step S43, the laser L is irradiated to the semiconductor substrate 21 with the LBA offset amount D8 (irradiation condition, condensing state D5) different from each other for each of the plurality of lines 15. As one example, in this case, the X offset amount is made constant, and the Y offset amount is changed from -2 to +2 in units of 0.5 as indicated by the Y offset variable range K74, and irradiation of the laser L is performed. Thus, on each of the lines 15, the modified regions 12a, 12b, and the like having different formation states are formed.

[0266] Next, the control section 10 performs a second process (step S44, second process) of acquiring information indicating the formation state of the modified regions 12a, 12b, and / or the cracks 14a to 14b by controlling the imaging unit 4 to perform imaging of the semiconductor substrate 21 with respect to the light II having transmittance with respect to the semiconductor substrate 21. In particular, in this step S44, information indicating the formation state is acquired for each of the plurality of lines 15. In this case, in the step S41, the lower crack amount F4 is designated as the determination item K5 (determination item K72), and thus at least imaging C5 and imaging C6 necessary to acquire the lower crack amount F4 are performed (other imaging can also be performed).

[0267] Next, the control section 10 performs a fourth process (step S45) of causing the input accepting section 103 to display information indicating the processing result (information acquired in the step S44) on the input accepting section 103 by controlling the input accepting section 103. Figure 49 is a view indicating the state in which the input accepting section displays the information indicating the processing result. As shown in Figure 49 in the step S45. In the information indicating the processing result K9, in addition to the LBA offset check K71, the determination item K72, the X offset variable range K73, the Y offset variable range K74, and the wafer thickness K75 described above, the determination K91, the X offset determination K92, the Y offset determination K93, the X offset K95, and the Y offset K96 are also displayed.

[0268] The determination K91 indicates whether or not the determination (i.e., derivation) of the LBA offset amount that becomes the desired formation state is completed. Here, as one example of the LBA offset amount that becomes the desired formation state, the LBA offset amount at which the amount of the lower cracks F4 shows a peak value is exemplified, but can also be a non-peak value, and can be set by the user. Here, in the determination K91, it is indicated that the determination is completed, i.e., it is indicated that the LBA offset amount at which the amount of the lower cracks F4 shows a peak value is obtained.

[0269] In addition, in the X offset determination K92, it is indicated that the value of the X offset amount at which the desired formation state (the amount of the lower cracks F4 shows a peak value) is obtained, and in the Y offset determination K93, it is indicated that the value of the Y offset amount at which the desired formation state (the amount of the lower cracks F4 shows a peak value) is obtained. That is, the control section 10, in a case where a peak value of the formation state is obtained, causes the irradiation condition (here, the LBA offset amount D8) corresponding to the peak value to be displayed on the input accepting section 103 by controlling the input accepting section 103. In addition, the control section 10, in the above-described first embodiment, can also cause the irradiation condition corresponding to the peak value to be displayed on the input accepting section 103 in a case where a peak value is obtained. In addition, even in a case where it is assumed that a peak value of the formation state is obtained, the control section 10 can cause the irradiation condition corresponding to a value shifted from the peak value to be displayed on the input accepting section 103. This is in order to have a margin in the irradiation condition with which the desired formation state can be obtained.

[0270] The X offset K95 includes a coordinate graph K951 and an internal image lower crack front K952, and the Y offset K96 includes a coordinate graph K961 and an internal image lower crack front K962. In the coordinate graph K951, the X offset amount is displayed in association with the amount of the lower cracks F4. In addition, in the coordinate graph K961, the Y offset amount is displayed in association with the amount of the lower cracks F4. In addition, in the information K9 indicating the processing result, for convenience, information on the X offset is also displayed in addition to the information on the Y offset, but at the current point in time, only processing that makes the Y offset amount variable is performed, and thus the information on the X offset is not displayed.

[0271] As shown in the coordinate graph K961, the amount of the lower cracks F4 becomes a peak value when the Y offset amount is ±0. Therefore, in the Y offset determination K93, ±0 is displayed as the Y offset amount at which the peak value of the amount of the lower cracks F4 is given. In addition, in the determination K91, the determination (derivation) of the Y offset amount at which the peak value of the amount of the lower cracks F4 is given is completed.

[0272] Thus, in the coordinate diagram K961, the relationship between the Y offset in the LBA offset D8 and the undercrack amount F4 is indicated. That is, in this process S45, the control section 10 performs the fourth process of displaying, by controlling the input accepting section 103, information indicating the irradiation conditions of the laser L in the process S43 (first processing) and information indicating the formation state acquired in the process S44 (second processing) in association with each other (coordinate diagram K961 in which the association is established) on the input accepting section 103.

[0273] In addition, the information indicating the formation state (formation state item) displayed in this process S45 is the undercrack amount F4 of the determination item K5 (determination item K72) set in the process S41. As described above, the determination item K5 can be selected. Therefore, in the process S41, the control section 10 performs the seventh process of causing information for facilitating selection of the formation state item displayed on the input accepting section 103 in the process S45 among the plurality of formation state items to be displayed on the input accepting section 103 by controlling the input accepting section 103.

[0274] In addition, the input accepting section 103 accepts selection of the formation state item in the process S41. Next, in the process S45, the control section 10 causes information indicating the formation state item (in this case, the undercrack amount F4) accepted by the input accepting section 103 and information indicating the irradiation conditions of the laser L (in this case, the LBA offset D8) to be displayed on the input accepting section 103 in association with each other by controlling the input accepting section 103.

[0275] In the next process, the control section 10 determines whether or not determination (derivation) of the LBA offset D8 (in this case, the Y offset) is completed, that is, whether or not the LBA offset at which the undercrack amount F4 shows a peak value is obtained (process S46). In the case where the result of the determination in the process S46 indicates that determination of the LBA offset D8 is completed (process S46: YES), processing is performed in accordance with the selection contents and the processing conditions displayed on the setting screen K7 (process S47, first processing). That is, in this case, the control section 10 performs the first processing of irradiating the laser L to each of the plurality of lines 15 so as to form the modified region 12a, 12b, or the like in the semiconductor substrate 21 in such a manner that the outer surface (the front surface 21a and the back surface 21b) of the semiconductor substrate 21 is not reached.

[0276] In particular, in this process S47, the laser L is irradiated to the semiconductor substrate 21 by different LBA offsets D8 (irradiation conditions, condensing states) for each of the plurality of lines 15. In this case, the Y offset is constant, and the X offset is changed from -6 to +6 as indicated by the X offset variable range K73, and the laser L is irradiated. Thus, on each of the lines 15, the modified regions 12a, 12b, or the like having different formation states are formed.

[0277] Next, the control section 10 executes a second process (step S48, second process) of acquiring information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a to 14b by imaging the semiconductor substrate 21 with the light II having the transmittance with respect to the semiconductor substrate 21 by controlling the imaging unit 4. In particular, in this step S48, the information indicating the formation state is acquired for each of the plurality of lines 15. Here, in the step S41, the lower crack amount F4 is designated as the determination item K5 (determination item K72), and thus at least the imaging C5 and the imaging C6 necessary to acquire the lower crack amount F4 are executed (other imaging can also be executed).

[0278] Next, the control section 10 executes a fifth process (step S49) of determining whether or not the cracks 14a, 14d reach the outer surface based on the information indicating the formation state acquired in the step S48. Here, in a case where at least one of the case where the second end 14ae of the crack 14a is not confirmed in the image acquired by the imaging C5 and the case where the crack 14d is confirmed on the back surface 21b in the image acquired by the imaging C0, it is determined that the cracks 14a, 14b reach the outer surface, rather than not reach (ST). In a case where the determination result in the step S49 is a result indicating that the cracks 14a, 14d reach the outer surface, that is, in a case of not reaching (step S49: No), the process proceeds to the step S41.

[0279] On the other hand, in a case where the determination result in the step S49 is a result indicating that the cracks 14a, 14d do not reach the outer surface, that is, in a case of reaching (step S49: Yes), the control section 10 executes a fourth process (step S50, third process) of causing the information indicating the processing result (the information acquired in the step S48) to be displayed on the input accepting section 103 by controlling the input accepting section 103. The information displayed here is the information K9 indicating the processing result shown in FIG. 9. At the point in time of the step S45, only the processing of making the Y offset amount variable is performed, and thus information on the X offset is not displayed. Here, the processing of making the X offset amount variable is also completed, and thus information on the X offset (all the items of the display K9) is also displayed. As shown in the coordinate diagram K951, the lower crack amount F4 becomes a peak value when the X offset amount is ±0 in the processing in the forward direction. In addition, the lower crack amount F4 becomes the maximum when the X offset amount is +3 in the processing in the return direction. Thus, in the X offset determination K92, ±0 and +3 (the X offset amount at which the maximum value is given) are displayed as the X offset amount at which the peak value of the lower crack amount F4 is given. In addition, in the determination K91, the determination (derivation) of the X offset amount at which the peak value of the lower crack amount F4 is given is completed. Figure 49 Figure 49

[0280] ​​In the coordinate chart K951, the relationship between the X offset in the LBA offset D8 and the undercrack amount F4 is shown. That is, in this process S50, the control section 10 performs the fourth process of displaying, by controlling the input accepting section 103, information showing the irradiation conditions of the laser L in the process S47 (first processing) and information showing the formation state acquired in the process S48 (second processing) in association with each other (coordinate chart K951 in which the association is established) on the input accepting section 103.

[0281] In addition, the information showing the formation state (formation state item) displayed in this process S50 is the undercrack amount F4 which is the determination item K5 (determination item K72) set in the process S41. As described above, the determination item K5 can be selected. Therefore, in the process S41, the control section 10 performs the seventh process of displaying, by controlling the input accepting section 103, information promoting the selection of the formation state item displayed on the input accepting section 103 in the process S48 among the plurality of formation state items on the input accepting section 103.

[0282] In addition, the input accepting section 103 accepts the selection of the formation state item in the process S41. Next, the control section 10 displays, by controlling the input accepting section 103, information showing the formation state item (in this case, the undercrack amount F4) accepted by the input accepting section 103 and information showing the irradiation conditions of the laser L (in this case, the LBA offset D8) in association with each other on the input accepting section 103 in the process S50.

[0283] In the next process, the control section 10 determines whether or not the determination (derivation) of the LBA offset D8 (in this case, the X offset) is completed (process S51). In the case where the result of the determination in the process S51 is the result showing that the determination of the LBA offset D8 is completed (process S51: Yes), the processing is ended. In addition, in the information K9 showing the processing result, information K97 promoting the selection of whether or not to change the value of the LBA offset D8 for which the determination is completed (the value displayed in the X offset determination K92 and the Y offset determination K93) is displayed. Thus, the user can select whether or not to change the value of the LBA offset D8 for which the determination is completed at the timing of displaying the information K9.

[0284] In this case, in the case where the result of the determination in the process S46 is the result showing that the determination of the Y offset is not completed (process S46: No) and the result of the determination in the process S51 is the result showing that the determination of the X offset is not completed (process S51: No), it is judged that the desired formation state (in this case, the peak) is not obtained in the variable range of the LBA offset D8 and the determination item selected previously, and the processing is shifted to the process S52 shown in Figure 46

[0285] ​That is, in the next process, the control section 10 expands the variable range of the LBA offset amount D8 (process S52). In the case of shifting from the process S46 to the process S52, the variable range of the Y offset amount in the LBA offset amount D8 is expanded from the Y offset variable range K74 (±2), and in the case of shifting from the process S51 to the process S52, the variable range of the X offset amount in the LBA offset amount D8 is expanded from the X offset variable range K73 (±6). Further, the following process is described for the determination of the Y offset amount, but the case of the determination of the X offset amount is the same.

[0286] In the next process, the determination is performed as to whether the machining condition (irradiation condition) corresponding to the expanded variable range in the process S52 is the condition in which the cracks 14a, 14d do not reach the outer surface, that is, the non-reached condition, by the 3rd processing (process S53). Here, the control section 10 can determine whether the condition corresponding to the expanded variable range is the non-reached condition, as in the above-described process S2. In the case of the result of the determination of this process S53 indicating that the machining condition is not the non-reached condition (process S53: No), the shift is made to the process S52 to adjust the degree of expansion of the variable range.

[0287] On the other hand, in the case of the result of the determination of the process S53 indicating that the machining condition is the non-reached condition (process S53: Yes), the machining is performed with the expanded variable range (process S54, 1st process). That is, here, the control section 10 performs the 1st processing of irradiating the laser L along each of the plurality of lines 15 to the semiconductor substrate 21 to form the modified regions 12a, 12b, and the like to the semiconductor substrate 21 in such a manner that the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21 is not reached.

[0288] In particular, in this process S54, the laser L is irradiated to the semiconductor substrate 21 with the Y offset amount (irradiation condition, condensing state) different from each other for each of the plurality of lines 15. Here, the X offset amount is made constant, and the Y offset amount is changed in the expanded variable range and the irradiation of the laser L is performed. Thus, on each of the lines 15, the modified regions 12a, 12b, and the like having different formation states are formed.

[0289] Next, the control section 10 performs the 2nd processing of acquiring information indicating the formation state of the modified regions 12a, 12b, and / or the cracks 14a to 14b by controlling the imaging unit 4 to perform imaging on the semiconductor substrate 21 with the light II having the transmittance with respect to the semiconductor substrate 21 (process S55, 2nd process). This process S55 is the same as the process S44 shown in Figure 45 Next, the control section 10 causes the information indicating the machining result to be displayed on the input accepting section 103 by controlling the input accepting section 103 (process S56). This process S56 is the same as the process S44 shown in Figure 45The process S45 shown is the same.

[0290] Next, the control unit 10 determines whether the determination (derivation) of the LBA offset D8 (in this case, the Y offset) has ended, that is, whether the LBA offset D8 that shows the peak value of the lower crack amount F4 is obtained within the expanded variable range (step S57). If the result of the determination in step S57 indicates that the determination of the LBA offset D8 has ended (step S57: no), the process ends.

[0291] On the other hand, if the result of the determination in process S57 indicates that the determination of LBA offset D8 has not ended (process S57: Yes), the control unit 10 changes the determination item (process S58). More specifically, in this case, the item used for determining LBA offset D8 in the formation state item is set to... Figure 47 The items other than the judgment item K5 (in this case, the lower crack amount F4) specified in the information K1 shown.

[0292] like Figure 50 As shown, in the case where the determination item is the front end position of the lower crack, F3 ( Figure 50 (a) and the case where the front end of the upper crack is F1 ( Figure 50 Under (b)), a peak value can be obtained corresponding to the change in Y offset, and the Y offset assigned to the peak value is the same as that obtained by the existing method through cross-sectional observation. Figure 50 The Y offset Oc in (c) is consistent. Additionally, as... Figure 51 As shown, even when the determined item is a crack with the front end position deviating from the width F6, the peak value can be approximated from the change in Y offset, and the Y offset of this peak value is assigned to the existing method through cross-sectional observation ( Figure 51 The Y offset Oc in (c) is consistent.

[0293] In addition, such as Figure 52 and Figure 53 As shown, even when the determination item is the presence or absence of scratches in the modified area (F7), it is possible to observe the change in the appearance of the scratches corresponding to the change in the Y offset. The clearest scratches are identified near the Y offset ±0 (the same Y offset as other determination items and existing methods). Thus, in process S58, various determination items can replace the aforementioned lower crack amount (F4).

[0294] Furthermore, the determination of the X offset is the same. As an example, such as... Figure 54 As shown, when the determined item is the lower crack amount F4, the peak value is obtained corresponding to the change in X offset, and the X offset of this peak value is compared with that of the existing method performed by cross-sectional observation ( Figure 54of (b) are consistent with each other (±0 (outgoing) and +2 (returning)). In addition, as shown in Figs. 8A and 8B, in the case where the determination item is the meandering amount F8 of the lower crack front end, it is also observed that the meandering amount F8 of the lower crack front end changes in correspondence with the change in the X offset amount, and the X offset amount that minimizes the meandering amount F8 of the lower crack front end is consistent with the above case. In this way, the determination for the X offset amount can also utilize various determination items. Figure 55 of (b) are consistent with each other (±0 (outgoing) and +2 (returning)). In addition, as shown in Figs. 8A and 8B, in the case where the determination item is the meandering amount F8 of the lower crack front end, it is also observed that the meandering amount F8 of the lower crack front end changes in correspondence with the change in the X offset amount, and the X offset amount that minimizes the meandering amount F8 of the lower crack front end is consistent with the above case. In this way, the determination for the X offset amount can also utilize various determination items. Figure 56 of (b) are consistent with each other (±0 (outgoing) and +2 (returning)). In addition, as shown in Figs. 8A and 8B, in the case where the determination item is the meandering amount F8 of the lower crack front end, it is also observed that the meandering amount F8 of the lower crack front end changes in correspondence with the change in the X offset amount, and the X offset amount that minimizes the meandering amount F8 of the lower crack front end is consistent with the above case. In this way, the determination for the X offset amount can also utilize various determination items.

[0295] Next, processing is performed (step S59), imaging is performed (step S60), and the result is displayed (step S62). Step S59 is the same as the above-described step S54, step S60 is the same as the above-described step S55, and step S62 is the same as the above-described step S56. However, in step S60, imaging is performed in which the determination item that was changed in step S58 can be obtained in imaging C1 to C11.

[0296] In addition, here, after step S60 and before step S62, the control section 10 performs a fifth process (step S61) of determining whether or not the cracks 14a, 14d have reached the outer surface, based on the information indicating the formation state that was obtained in step S60. Here, in the case of at least one of the case where the second end 14ae of the crack 14a is not confirmed in the image obtained by imaging C5, and the case where the crack 14d is confirmed on the back surface 21b in the image obtained by imaging C0, it can be determined that the cracks 14a, 14b have reached the outer surface, rather than not having reached. In the case where the result of the determination in step S61 is a result indicating that the cracks 14a, 14d have reached the outer surface, i.e., the case of not having reached (step S61: No), the process proceeds to step S58, and in the case of a result indicating that the cracks 14a, 14b have not reached the outer surface, i.e., the case of having reached (step S61: Yes), the process proceeds to step S62 as described above.

[0297] Next, the control section 10 determines whether or not the determination (derivation) of the LBA offset amount D8 (here, the Y offset amount) is complete, i.e., determines whether or not the changed determination item has obtained the LBA offset amount D8 that exhibits the peak value (the desired state) (step S63). In the case where the result of the determination in step S63 is a result indicating that the determination of the LBA offset amount D8 is complete (step S63: No), the process is ended.

[0298] On the other hand, in a case where the result of the determination in the step S63 is a result indicating that the determination of the LBA offset D8 is not completed (step S63: Yes), the control section 10 changes the irradiation conditions other than the above-mentioned irradiation condition items such as the intensified condensing correction (step S64). Subsequently, the processing (step S65), the imaging (step S66), and the result display (step S68) are performed. The step S65 is the same as the above-mentioned step S54, the step S66 is the same as the above-mentioned step S55, and the step S68 is the same as the above-mentioned step S56.

[0299] However, here, after the step S66 and before the step S68, the control section 10 performs the 5th processing of determining whether or not the cracks 14a, 14d reach the outer surface based on the information indicating the formation state acquired by the step S65 (step S67). In a case where at least one of a case where the 2nd end 14ae of the crack 14a is not confirmed in the image acquired by the imaging C5 and a case where the crack 14d is confirmed on the back surface 21b in the image acquired by the imaging C0, it is possible to determine that the cracks 14a, 14b reach the outer surface. In a case where the result of the determination in the step S67 is a result indicating that the cracks 14a, 14d reach the outer surface, i.e., a case other than the non-reached case (step S67: No), the processing is shifted to the step S64, and in a case where the result is a result indicating that the cracks 14a, 14b do not reach the outer surface, i.e., the non-reached case (step S67: Yes), the processing is shifted to the step S68 as described above.

[0300] Subsequently, the control section 10 determines whether or not the determination (derivation) of the LBA offset D8 (here, the Y offset) is completed, i.e., determines whether or not the LBA offset D8 that shows the peak value (the desired state) is obtained with the changed irradiation conditions (step S69). In a case where the result of the determination in the step S69 is a result indicating that the determination of the LBA offset D8 is completed (step S69: No), the processing is ended.

[0301] On the other hand, in a case where the result of the determination in the step S69 is a result indicating that the determination of the LBA offset D8 is not completed (step S69: Yes), the control section 10 causes the information indicating the error to be displayed on the input accepting section 103 by controlling the input accepting section 103 (step S70), and ends the processing. This is because, since none of the enlargement of the variable range of the LBA offset D8, the change of the determination item, and the change of the irradiation conditions obtains the desired formation state, there is a possibility that the device state is abnormal.

[0302] [Explanation of Effects]

[0303] As explained above, in the laser processing apparatus 1 and the laser processing method of the above-described embodiment, the modified regions 12a, 12b, etc. (the modified regions 12a, 12b and the cracks 14a to 14d extending from the modified regions 12a, 12b) are formed by irradiating the laser L to the semiconductor substrate 21 along each of the plurality of lines 15. At this time, the irradiation conditions are set to be different for each line 15. Then, the formation states (processing results) of the modified regions 12a, 12b, etc. are acquired for each of the plurality of lines 15 by imaging the semiconductor substrate 21 with the light II that has passed through the semiconductor substrate 21. Further, after that, the irradiation conditions of the laser L and the formation states of the modified regions 12a, 12b, etc. are correlated with each other and acquired for each of the plurality of lines 15. Therefore, when the irradiation conditions of the laser L are adjusted, it is not necessary to cut the semiconductor substrate 21 or to perform cross-sectional observation. Therefore, according to the laser processing apparatus 1 and the laser processing method of the above-described embodiment, it is possible to simplify the adjustment of the irradiation conditions of the laser L.

[0304] In particular, in the laser processing apparatus 1 and the laser processing method of the above-described embodiment, it is possible to grasp the correlation between the formation states of the modified regions 12a, 12b and the irradiation conditions of the laser L in a state where the modified regions 12a, 12b and the cracks 14a to 14d do not emerge on the outer surfaces (the front surface 21a and the back surface 21b) of the semiconductor substrate 21. Therefore, compared to a state where the cracks 14a to 14d reach the outer surfaces, it is less likely to be affected by influences from the outside (for example, vibration or secular change). Therefore, it is possible to avoid a case where the cracks 14a to 14d unexpectedly progress during transportation and the semiconductor substrate 21 is divided.

[0305] Further, in the laser processing apparatus 1 of the above-described embodiment, the control section 10 performs the third process of determining whether the irradiation conditions are the non-reached conditions that are conditions where the cracks 14a, 14d do not reach the outer surfaces before the first process. Then, the first process is performed in a case where the result of the determination of the third process is that the irradiation conditions are the non-reached conditions. Therefore, it is possible to reliably perform processing in a manner such that the cracks 14a, 14d do not reach the outer surfaces of the object.

[0306] Further, the laser processing apparatus 1 of the above-described embodiment is provided with the input reception section 103 for displaying information and for receiving input. Therefore, it is possible to prompt information to the user and to receive input of information from the user.

[0307] Further, in the laser processing apparatus 1 of the above-described embodiment, the control section 10 performs the fourth process of causing the information acquired by the second process to be displayed on the input reception section 103 by controlling the input reception section 103 after the second process. Therefore, it is possible to prompt the user with information in which the irradiation conditions of each laser L and the formation states of the modified regions 12a, 12b, etc. are correlated with each other.

[0308] Further, in the laser processing apparatus 1 of the above-described embodiment, the control section 10 performs, after the second process and before the fourth process, a fifth process of determining whether or not the cracks 14a, 14d reach the outer surface, based on the information indicating the formation state acquired by the second process. Then, the fourth process is performed in the case where the result of the determination of the fifth process is that the cracks 14a, 14b do not reach the outer surface. Thus, it is possible to reliably display the correlation between the irradiation conditions of the laser L and the formation state of the modified regions 12a, 12b, etc. in the state where the cracks 14a, 14d do not reach the outer surface of the object.

[0309] Further, in the laser processing apparatus 1 of the above-described embodiment, the control section 10 performs, before the first process, a sixth process of causing the input accepting section 103 to display information for facilitating selection of a variable item that differs for each line 15 among the plurality of irradiation condition items included in the irradiation condition in the first process, by controlling the input accepting section 103. Further, the input accepting section 103 accepts input of the selection of the variable item. Then, the control section 10 controls the laser irradiation unit 3 so that the first process is performed in a manner in which the variable item accepted by the input accepting section 103 differs for each line 15. Thus, adjustment of the desired irradiation condition is easy.

[0310] Further, in the laser processing apparatus 1 of the above-described embodiment, the irradiation condition includes, as the irradiation condition item, a pulse width (pulse width D2) of the laser L, a pulse energy (pulse energy D3) of the laser L, a pulse pitch (pulse pitch D4) of the laser L, and a condensing state (condensing state D5) of the laser L.

[0311] Further, the laser processing apparatus 1 of the above-described embodiment includes the spatial light modulator 5 that displays a spherical aberration correction pattern for correcting spherical aberration of the laser L, and the condensing lens 33 for condensing the laser L modulated by the spherical aberration correction pattern in the spatial light modulator 5 to the semiconductor substrate 21. The condensing state D5 includes an offset amount (LBA offset amount D8) of the center of the spherical aberration correction pattern with respect to the center of the entrance pupil face 33a of the condensing lens 33.

[0312] Further, in the case where the irradiation condition forms a plurality of modified regions 12a, 12b at positions different from each other in the Z direction intersecting the laser L incident face (back face 21b) of the semiconductor substrate 21 in the first process, the irradiation condition includes, as the irradiation condition item, a pitch (modified region pitch D1) of the modified regions 12a, 12b in the Z direction.

[0313] In these cases, adjustment of the above-described items in the irradiation condition of the laser L becomes easy.

[0314] Further, in the laser processing apparatus 1 of the above-described embodiment, in a case where the control section 10 has acquired the peak in the formation state in the second process, in the third process, the control section 10 causes the irradiation conditions corresponding to the peak to be displayed on the input reception section 103 by controlling the input reception section 103. Thus, it is possible to easily adjust the irradiation conditions of the laser L to conditions in which the formation state of the modified region 12a, 12b becomes a peak.

[0315] Further, in the laser processing apparatus 1 of the above-described embodiment, the semiconductor substrate 21 includes the back surface 21b as the incident surface of the laser L and the surface 21a on the opposite side of the back surface 21b. The cracks include the crack 14d extending from the modified region 12b toward the back surface 21b and the crack 14a extending from the modified region 12a toward the surface 21a. Thus, the formation state includes the length of the crack 14b in the Z direction (the upper crack amount F2), the length of the crack 14a in the Z direction (the lower crack amount F4), the total amount of the lengths of the cracks 14a to 14d in the Z direction (the total crack amount F5), the position of the first end 14de of the crack 14d on the back surface 21b side, i.e., the first end 14de in the Z direction (the upper crack tip position F1), the position of the second end 14ae of the crack 14a on the surface 21a side, i.e., the second end 14ae in the Z direction (the lower crack tip position F3), the deviation width of the first end 14de and the second end 14ae when viewed in the Z direction (the upper and lower crack tip position deviation width F6), the presence or absence of a mark of the modified region 12a, 12b (the presence or absence of a modified region mark F7), and the amount of meandering of the second end 14ae when viewed in the Z direction (the amount of meandering of the lower crack tip F8) as the formation state items. Thus, it is possible to easily perform adjustment of the irradiation conditions of the laser L in the formation state of the modified region 12a, 12b, etc. based on the above-described items.

[0316] [Explanation of Modified Examples]

[0317] The above-described embodiment is a mode of explaining one aspect of the present application. Thus, the present application is not limited to the above-described embodiment and can be arbitrarily changed.

[0318] For example, in the above-described embodiment, as the processing of the laser processing apparatus 1, an example in which the wafer 20 is cut along each of the plurality of lines 15 by each functional element 22a (an example of dicing) is cited. However, the laser processing apparatus 1 can also be applied to processing of cutting an object along an imaginary surface (within the object) opposite to the incident surface of the laser of the object (processing of peeling in the thickness direction), or trimming processing of cutting a ring-shaped region including the outer edge of the object from the object, and the like.

[0319] In addition, in the above-described embodiments, as the object of the laser processing apparatus 1, a wafer 20 including a semiconductor substrate 21 that is a silicon substrate is exemplified. However, the object of the laser processing apparatus 1 is not limited to one including silicon.

[0320] In addition, in the above-described embodiments, as the irradiation condition item, the formation state item, and the combination thereof, a part is exemplified, but is not limited to the irradiation condition item, the formation state item, and the combination thereof exemplified in the above-described embodiments, and can be arbitrarily selected. For example, in the first embodiment, the determination of whether or not the LBA offset D8 exemplified in the third embodiment is acceptable can also be performed.

[0321] In addition, in the above-described embodiments, in a case where the irradiation condition to be the prescribed formation state is automatically adjusted after the information on the formation state of the modified region 12a, 12b, or the like is acquired by the second process, a process of displaying the information acquired by the second process is not required.

[0322] In addition, in the above-described examples, one example of the timing of execution is indicated in a case where the process of determining whether or not the irradiation condition for processing is the unachieved condition (the third process) is performed before the process of receiving the setting of the irradiation condition for the processing is performed, and in a case where the process of performing the processing is performed, and the process of determining whether or not the cracks 14a, 14d are unachieved to the outer surface (the fifth process) is performed after the process of acquiring the information indicating the formation state is performed. However, the timing of execution of these processes is not limited to the above-described examples, but is arbitrary.

[0323] Industrial Applicability

[0324] The present application can provide a laser processing apparatus and a laser processing method capable of simplifying the adjustment of the irradiation condition of laser.

[0325] Explanation of Symbols

[0326] 1... laser processing apparatus, 3... laser irradiation unit (irradiation section), 4... imaging unit (imaging section), 5... spatial light modulator, 10... control section, 11... object, 21... semiconductor substrate, 33... condenser lens, 33a... entrance pupil plane, 103... input reception section (input section, display section).

Claims

1. A laser processing apparatus, wherein, have: An irradiation unit, used to irradiate an object with laser light; A camera unit for capturing images of the object; and The control unit controls at least the irradiation unit and the camera unit. The object has multiple lines. The control unit performs: The first process, controlled by the irradiation unit, irradiates the object with the laser along each of the plurality of lines, forming modified particles and cracks extending from the modified particles on the object in such a way that the laser does not reach the outer surface of the object, which includes a first surface that serves as the incident surface of the laser and a second surface opposite to the first surface. as well as The second process, following the first process, involves, under the control of the imaging unit, capturing an image of the object using light that is translucent relative to the object, and acquiring information representing the formation state of the modified particles and / or the cracks for each of the plurality of lines. In the first process, the object is irradiated with the laser at each of the plurality of lines under different irradiation conditions. In the second process, for each of the plurality of lines, the information representing the laser irradiation conditions from the first process is correlated with the information representing the formation state to obtain the result. In the second process, at least the following images are captured: The object is photographed by aligning the focal point of the translucent light with the front end of the lower cracked virtual image, so that the focal point of the translucent light is aligned from the second surface side with respect to the front end of the second surface side of the lower crack. as well as To capture an image of the object, the focal point of the translucent light is aligned with the front end of the virtual image of the modified particle on the second surface side. in, The lower crack is a crack that extends from the modified particle on the second surface side toward the second surface side. The virtual image of the lower crack is an image of the lower crack positioned symmetrically with respect to the second surface. The virtual image of the modified particle is the image of the modified particle at a position symmetrical with respect to the second surface.

2. The laser processing apparatus as described in claim 1, wherein, The control unit performs a third process, which, prior to the first process, determines whether the irradiation condition is a non-reaching condition, which is a condition under which the crack has not reached the outer surface. If the result of the determination in the third process is that the irradiation condition is the condition that has not been reached, then the first process is performed.

3. The laser processing apparatus as described in claim 1, wherein, have: A display unit, used to display information; and The input section is used to accept input.

4. The laser processing apparatus as described in claim 2, wherein, have: A display unit, used to display information; and The input section is used to accept input.

5. The laser processing apparatus as described in claim 3, wherein, The control unit performs a fourth process, which, after the second process, displays the information obtained from the second process on the display unit under the control of the display unit.

6. The laser processing apparatus as described in claim 4, wherein, The control unit performs a fourth process, which, after the second process, displays the information obtained from the second process on the display unit under the control of the display unit.

7. The laser processing apparatus as described in claim 5, wherein, The control unit performs a fifth process, which, after the second process and before the fourth process, determines whether the crack has not reached the outer surface based on information indicating the formation state obtained from the second process. If the result of the fifth process is that the modified particles and the cracks have not reached the outer surface, the fourth process is performed.

8. The laser processing apparatus as described in claim 6, wherein, The control unit performs a fifth process, which, after the second process and before the fourth process, determines whether the crack has not reached the outer surface based on information indicating the formation state obtained from the second process. If the result of the fifth process is that the modified particles and the cracks have not reached the outer surface, the fourth process is performed.

9. The laser processing apparatus according to any one of claims 3 to 8, wherein, The control unit performs a sixth process, which, prior to the first process, displays information on the display unit regarding the selection of variable items, different for each line, among the multiple irradiation condition items included in the irradiation conditions of the first process, under the control of the display unit. The input section accepts input for selecting the variable item. The control unit, under the control of the irradiation unit, performs the first process in a different manner for each of the variable items received by the input unit according to the different methods of each line.

10. The laser processing apparatus as described in claim 9, wherein, The irradiation conditions include at least one of the following items as irradiation condition items: The pulse waveform of the laser; The pulse energy of the laser; The pulse spacing of the laser; The focusing state of the laser; and In the case where multiple modified particles are formed at different positions in the direction intersecting the incident surface of the laser on the object during the first process, the spacing of the modified particles in the direction intersecting the incident surface.

11. The laser processing apparatus as claimed in claim 10, wherein, have: A spatial light modulator that displays a spherical aberration correction pattern for correcting spherical aberration of the laser; as well as A focusing lens for focusing the laser light, modulated in the spatial light modulator by the spherical aberration correction pattern, onto the object. The focusing state includes an offset of the center of the spherical aberration correction pattern relative to the center of the pupil surface of the focusing lens.

12. The laser processing apparatus according to any one of claims 5 to 8, wherein, When the control unit obtains the peak value of the formation state through the second process, in the fourth process, the irradiation conditions corresponding to the peak value are displayed on the display unit under the control of the display unit.

13. The laser processing apparatus according to any one of claims 5 to 8, wherein, The control unit performs a seventh process, which, prior to the fourth process, displays information on the display unit regarding the selection of one of the multiple formation state items included in the formation state that was displayed on the display unit during the fourth process. The input unit accepts input from the selection of the formation status item. In the fourth process, the control unit, under the control of the display unit, establishes and displays information representing the formation state item received by the input unit in the formation state and information representing the irradiation conditions.

14. The laser processing apparatus as described in claim 12, wherein, The control unit performs a seventh process, which, prior to the fourth process, displays information on the display unit regarding the selection of one of the multiple formation state items included in the formation state that was displayed on the display unit during the fourth process. The input unit accepts input from the selection of the formation status item. In the fourth process, the control unit, under the control of the display unit, establishes and displays information representing the formation state item received by the input unit in the formation state and information representing the irradiation conditions.

15. The laser processing apparatus as described in claim 13, wherein, The crack includes a first crack extending from the modified particle towards the first surface side and a second crack extending from the modified particle towards the second surface side. The formation state includes at least one of the following items as the formation state item: The length of the first crack in the first direction intersecting the first surface; The length of the second crack in the first direction; The total length of the cracks in the first direction; The position of the first end of the first surface side of the first crack in the first direction; The position of the second end of the front end of the second surface side of the second crack in the first direction; The deviation width between the first end and the second end when viewed from the first direction; The presence or absence of traces of the modified particle; The amount of bend at the second end when viewed from the first direction; as well as In the case where multiple modified particles are formed at different positions in a direction intersecting the first surface during the first process, the presence or absence of the leading edge of the crack in the region between the modified particles arranged in the direction intersecting the first surface.

16. The laser processing apparatus as described in claim 14, wherein, The crack includes a first crack extending from the modified particle towards the first surface side and a second crack extending from the modified particle towards the second surface side. The formation state includes at least one of the following items as the formation state item: The length of the first crack in the first direction intersecting the first surface; The length of the second crack in the first direction; The total length of the cracks in the first direction; The position of the first end of the first surface side of the first crack in the first direction; The position of the second end of the front end of the second surface side of the second crack in the first direction; The deviation width between the first end and the second end when viewed from the first direction; The presence or absence of traces of the modified particle; The amount of bend at the second end when viewed from the first direction; as well as In the case where multiple modified particles are formed at different positions in a direction intersecting the first surface during the first process, the presence or absence of the leading edge of the crack in the region between the modified particles arranged in the direction intersecting the first surface.

17. A laser processing method, wherein, have: In the first step, lasers are irradiated onto the object along each of a plurality of lines set on the object, forming modified particles and cracks extending from the modified particles on the object in such a way that the outer surface of the object, which includes a first surface that serves as the incident surface of the laser and a second surface opposite to the first surface, is not reached. as well as The second step, following the first step, involves photographing the object using light that is translucent relative to the object, and acquiring information representing the formation state of the modified particles and / or the cracks for each of the plurality of lines. In the first step, the object is irradiated with the laser at each of the plurality of lines under different irradiation conditions. In the second step, for each of the plurality of lines, the information representing the laser irradiation conditions from the first step is correlated with the information representing the formation state to obtain the information. In the second step, at least the following video recordings shall be performed: The object is photographed by aligning the focal point of the translucent light with the front end of the lower cracked virtual image, so that the focal point of the translucent light is aligned from the second surface side with respect to the front end of the second surface side of the lower crack. as well as To capture an image of the object, the focal point of the translucent light is aligned with the front end of the virtual image of the modified particle on the second surface side. in, The lower crack is a crack that extends from the modified particle on the second surface side toward the second surface side. The virtual image of the lower crack is an image of the lower crack positioned symmetrically with respect to the second surface. The virtual image of the modified particle is the image of the modified particle at a position symmetrical with respect to the second surface.

Images