Laser processing apparatus and laser processing method

Abstract

A laser processing apparatus includes an irradiation section configured to irradiate a laser beam toward an object, an imaging section configured to image the object by light that is transmissive to the object, a display section configured to display information, and a control section configured to control at least the irradiation section, the imaging section, and the display section. The control section performs a first process of forming a modified point and a crack extending from the modified point in the object by controlling the irradiation section to irradiate the laser beam toward the object in a manner that the laser beam does not reach an outer surface of the object, a second process of imaging the object by controlling the imaging section after the first process to acquire information indicating a formation state of the modified point and / or the crack, and a third process of associating information indicating an irradiation condition of the laser beam in the first process with the information indicating the formation state acquired in the second process and displaying the information on the display section after the second process.

Description

TECHNICAL FIELD

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

[0002] A laser cutting apparatus is described in Patent Literature 1. The laser cutting apparatus is provided with a stage that moves a wafer, a laser head that irradiates a laser to the wafer, and a control section that controls each section. The laser head has a laser source that emits a processing laser for forming a modified region inside the wafer, a beam splitter and a condenser lens that are sequentially arranged on an optical path of the processing laser, and an auto-focusing device.

[0003] [Related 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 the laser to the above-described object such as a wafer to a condition that enables a desired processing result to be obtained, it is assumed that the correlation between the irradiation condition and the processing result is grasped as described below. That is, first, laser processing is performed under a predetermined irradiation condition. Thereafter, the object is cut in a manner that a cross section in which the modified region or the like is formed is exposed. And, by observing the cut surface, the actual processing result with respect to the irradiation condition can be grasped.

[0008] On the other hand, by 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 above-described technical field, it is desired that the correlation between the irradiation condition and the processing result can be easily grasped.

[0009] An object of the present application is to provide a laser processing apparatus and a laser processing method in which the correlation between the irradiation condition of a laser and a processing result can be easily grasped.

[0010] [Means of Solving the Problems]

[0011] The laser processing apparatus of the present application includes: an irradiation section configured to irradiate a laser beam to an object; an imaging section configured to image the object by light that is transmissive to the object; a display section configured to display information; and a control section configured to control at least the irradiation section, the imaging section, and the display section, wherein the control section performs: a first process of forming a modified point and a crack extending from the modified point in the object in such a manner that the modified point and the crack do not reach an outer surface of the object by controlling the irradiation section to irradiate the laser beam to the object; a second process of imaging the object by controlling the imaging section to image the object after the first process, and acquiring information indicating a formation state of the modified point and / or the crack; and a third process of causing information indicating a laser irradiation condition in the first process and the information indicating the formation state acquired in the second process to be associated with each other and displayed on the display section after the second process.

[0012] The laser processing method of the present application includes: a first process of forming a modified point and a crack extending from the modified point in an object in such a manner that the modified point and the crack do not reach an outer surface of the object by irradiating a laser beam to the object; a second process of imaging the object by light that is transmissive to the object after the first process, and acquiring information indicating a formation state of the modified point and / or the crack; and a third process of causing information indicating a laser irradiation condition in the first process and the information indicating the formation state acquired in the second process to be associated with each other and displayed after the second process.

[0013] In these apparatus and method, after the modified point and the like (the modified point and the crack extending from the modified point) are formed in the object by irradiating the laser beam to the object, the object is imaged by the light that is transmissive to the object, and the formation state (processing result) of the modified point and the like is acquired. Then, the laser irradiation condition and the formation state of the modified point and the like are caused to be associated with each other and displayed. Therefore, when the correlation between the laser irradiation condition and the processing state is grasped, it is not necessary to cut the object or perform cross-sectional observation. Therefore, by the apparatus and method, the correlation between the laser irradiation condition and the processing state can be easily grasped.

[0014] In the laser processing apparatus of the present application, the control section can perform a fourth process before the first process, in which it is determined whether the irradiation condition is a non-reach condition in which the crack does not reach the outer surface, and the first process can be performed when the determination result of the fourth process is that the irradiation condition is the non-reach condition. In this case, the processing can be surely performed in such a manner that the crack does not reach the outer surface of the object.

[0015] In the laser processing apparatus of the present application, the control section can execute a fifth process after the second process and before the third process, the fifth process being a process of judging whether or not the crack reaches the outer surface based on the information indicating the formation state acquired in the second process, and the third process can be executed in a case where the result of the judgment in the fifth process is that the crack does not reach the outer surface. In this case, the irradiation condition and the formation state can be surely associated and displayed with the crack not reaching the outer surface of the object.

[0016] In the laser processing apparatus of the present application, an input section for accepting input can be provided. In this case, input of information from the user can be accepted.

[0017] In the laser processing apparatus of the present application, the control section can execute a sixth process, the sixth process being a process of causing the display section to display information for guiding selection of the formation state item displayed on the display section in the third process among the plurality of formation state items included in the formation state by controlling the display section, the input section can accept input of the selection of the formation state item, and the control section can associate and display, in the third process, the information indicating the formation state item accepted by the input section and the information indicating the irradiation condition in the display section by controlling the display section.

[0018] At this time, the object includes a first surface as an incident surface of the laser and a second surface on the opposite side of the first surface, the crack includes a first crack extending from the modification point toward the first surface and a second crack extending from the modification point toward the second surface, and the formation state includes at least one of the items as the 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, which is a leading end of the first surface side of the first crack, in the first direction; a position of a second end, which is a leading 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 in the first direction; presence or absence of a trace of the modification point; a meandering amount of the second end when viewed in the first direction; and, in a case where a plurality of modification points are formed at different positions from each other in a direction intersecting the first surface in the first process, presence or absence of a leading end of the crack in a region between the modification points arranged in the direction intersecting the first surface.

[0019] In this case, the association between the item selected by the user and the irradiation condition among the formation states of the modification points and the like can be easily grasped.

[0020] In the laser processing apparatus of the present application, the control section can execute a seventh process, and in the seventh process, the display section displays information for guiding selection of an irradiation condition item displayed on the display section in the third process from among a plurality of irradiation condition items included in the irradiation condition, the input section accepts input of selection of the irradiation condition item, and the control section associates and displays, on the display section, information indicating the irradiation condition item accepted by the input section and information indicating the formation state in the third process.

[0021] At this time, the irradiation condition includes at least one of the following items as the irradiation condition item: pulse width of the laser light; pulse energy of the laser light; pulse interval of the laser light; condensing state of the laser light; and interval of the modified points in the direction intersecting the incident surface of the object in the case where a plurality of modified points are formed at different positions from each other in the direction intersecting the incident surface of the object in the first process. The control section associates and displays, on the display section, at least one of the information indicating the irradiation condition item and the information indicating the formation state in the third process.

[0022] Further, in the laser processing apparatus, the laser processing apparatus can include: a spatial light modulator that displays a spherical aberration correction pattern for correcting spherical aberration of the laser light; and a condensing lens that condenses the laser light modulated by the spherical aberration correction pattern in the spatial light modulator on the object, and the condensing state includes an amount of deviation of a center of the spherical aberration correction pattern with respect to a center of a pupil surface of the condensing lens.

[0023] In this case, it is possible to easily grasp the correlation between the item selected by the user and the formation state from among the irradiation conditions of the laser light.

[0024] In the laser processing apparatus of the present application, the control section can display, on the display section, a graph in which information indicating the irradiation condition and information indicating the formation state are associated with each other in the third process. In this case, it is possible to visually grasp the correlation between the irradiation condition of the laser light and the formation state of the modified points and the like.

[0025] [Effects of Invention]

[0026] According to the present application, it is possible to provide a laser processing apparatus and a laser processing method in which it is possible to easily grasp the correlation between the irradiation condition of the laser light and the processing state. BRIEF DESCRIPTION OF DRAWINGS

[0027] [ Figure 1 ] is a schematic view showing the structure of a laser processing apparatus according to an embodiment.

[0028] [ Figure 2 ] is a plan view of a wafer according to an embodiment.

[0029] [ Figure 3 ] is a cross-sectional view of a portion of a wafer. Figure 2

[0030] [ Figure 4 ] is a schematic view of a structure of a laser irradiation unit. Figure 1

[0031] [ Figure 5 ] is a view of a relay lens unit. Figure 4

[0032] [ Figure 6 ] is a cross-sectional view of a portion of a spatial light modulator. Figure 4

[0033] [ Figure 7 ] is a schematic view of a structure of an imaging unit. Figure 1

[0034] [ Figure 8 ] is a schematic view of a structure of an imaging unit. Figure 1

[0035] [ Figure 9 ] is a cross-sectional view of a wafer to explain an imaging principle of an imaging unit shown in Figure 7 , and a view of an image of each part obtained by the imaging unit.

[0036] [ Figure 10 ] is a cross-sectional view of a wafer to explain an imaging principle of an imaging unit shown in Figure 7 , and a view of an image of each part obtained by the imaging unit.

[0037] [ Figure 11 ] is a SEM image of a modified region and a crack formed in the inside of a semiconductor substrate.

[0038] [ Figure 12 ] is a SEM image of a modified region and a crack formed in the inside of a semiconductor substrate.

[0039] [ Figure 13 ] is an optical path diagram to explain an imaging principle of an imaging unit shown in Figure 7 , and a schematic view of an image indicating a focal point of the imaging unit.

[0040] [ Figure 14 ] is an optical path diagram to explain an imaging principle of an imaging unit shown in Figure 7 , and a schematic view of an image indicating a focal point of the imaging unit.

[0041] [ Figure 15 ] is an optical path diagram to explain an imaging principle of an imaging unit shown in​​​​​​Figure 7 A cross-sectional view of a wafer, an image of a cut surface of the wafer, and images of each portion obtained by the camera unit.

[0042] [ Figure 16 ] is a cross-sectional view of an object to explain the method of acquiring the formation state. Figure 7 A cross-sectional view of a wafer, an image of a cut surface of the wafer, and images of each portion obtained by the camera unit.

[0043] [ Figure 17 ] is a cross-sectional view of an object to explain the method of acquiring the formation state.

[0044] [ Figure 18 ] is a graph showing the change in the amount of cracking in the case where the interval of the modified region is changed at three points.

[0045] [ Figure 19 ] is a graph showing the change in the amount of cracking in the case where the interval of the modified region is changed at three points.

[0046] [ Figure 20 ] is a graph showing the change in the amount of cracking in the case where the pulse width of the laser light is changed at three points.

[0047] [ Figure 21 ] is a graph showing the change in the amount of cracking in the case where the pulse width of the laser light is changed at three points.

[0048] [ Figure 22 ] is a graph showing the change in the amount of cracking in the case where the pulse energy of the laser light is changed at three points.

[0049] [ Figure 23 ] is a graph showing the change in the amount of cracking in the case where the pulse energy of the laser light is changed at three points.

[0050] [ Figure 24 ] is a graph showing the change in the amount of cracking in the case where the pulse interval of the laser light is changed at four points.

[0051] [ Figure 25 ] is a graph showing the change in the amount of cracking in the case where the pulse interval of the laser light is changed at four points.

[0052] [ Figure 26 ] is a graph showing the change in the amount of cracking in the case where the condensing state (spherical aberration correction level) of the laser light is changed at three points.

[0053] [ Figure 27 ] is a graph showing the change in the amount of cracking in the case where the condensing state (spherical aberration correction level) of the laser light is changed at three points.

[0054] [Figure 28 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0055] [ Figure 29 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0056] [ Figure 30 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0057] [ Figure 31 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0058] [ Figure 32 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0059] [ Figure 33 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points. Figure 1 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0060] [ Figure 34 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0061] [ Figure 35 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0062] [ Figure 36 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0063] [ Figure 37 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0064] [ Figure 38 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0065] [ Figure 39 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0066] [ Figure 40 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points. Figure 1 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0067] [ Figure 41 FIG. 1 is a graph showing the change in the amount of cracking in the case where the condensing state (level of correction of astigmatism) of laser light is changed at three points.

[0068] [Figure 42 ] is a diagram showing a state in which information indicating a processing result is displayed.

[0069] [ Figure 43 ] is a graph showing a relationship between an irradiation condition and a formation state.

[0070] [ Figure 44 ] is a graph showing a relationship between a Y deviation amount and a formation state.

[0071] [ Figure 45 ] is a flowchart showing main procedures of a derivation method of an LBA deviation amount.

[0072] [ Figure 46 ] is a flowchart showing main procedures of a derivation method of an LBA deviation amount.

[0073] [ Figure 47 ] is a diagram of an input accepting section showing a state in which information indicating a selection of a guide check condition is displayed.

[0074] [ Figure 48 ] is a diagram of an input accepting section showing a state in which a setting screen is displayed.

[0075] [ Figure 49 ] is a diagram of an input accepting section showing a state in which information indicating a processing result is displayed.

[0076] [ Figure 50 ] is a graph showing a relationship between a Y deviation amount and a judgment item.

[0077] [ Figure 51 ] is a graph showing a relationship between a Y deviation amount and a judgment item.

[0078] [ Figure 52 ] is a graph showing a relationship between a Y deviation amount and a judgment item.

[0079] [ Figure 53 ] is a graph showing a relationship between a Y deviation amount and a judgment item.

[0080] [ Figure 54 ] is a graph showing a relationship between an X deviation amount and a judgment item.

[0081] [ Figure 55 ] is a graph showing a relationship between an X deviation amount and a judgment item.

[0082] [ Figure 56 ] is a graph showing a relationship between an X deviation amount and a judgment item. DETAILED DESCRIPTION

[0083] Hereinafter, an embodiment will be described in detail with reference to the drawings. Note that in each drawing, the same or equivalent portions will be denoted by the same reference signs, and repetitive description will be omitted. Also, in the drawings, a rectangular coordinate system defined by an X axis, a Y axis, and a Z axis will be indicated at times.

[0084] Figure 1 is a schematic view of the structure of a laser processing apparatus according to 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, and 8, a drive unit 9, and a control section 10. The laser processing apparatus 1 is an apparatus that irradiates a laser L against an object 11 to form a modified region 12 in the object 11.

[0085] The stage 2 supports the object 11, for example, by adsorbing a film attached to the object 11. The stage 2 is capable of moving along the X direction and the Y direction, respectively, and is capable of rotating with an axis parallel to the Z direction as a center line. Note that 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.

[0086] The laser irradiation unit (irradiation section) 3 condenses and irradiates the laser L having transmissivity against the object 11. When the laser L is condensed inside the object 11 supported by the stage 2, the laser L is particularly absorbed at a portion corresponding to a condensing point C of the laser L, thereby forming the modified region 12 inside the object 11.

[0087] The modified region 12 is a region whose density, refractive index, mechanical strength, or other physical characteristics are different from those of the surrounding non-modified 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 obtained by forming a crack so as to extend from the modified region 12 toward the incident side and the opposite side of the laser L. Such a modified region 12 and crack are utilized in cutting of the object 11, for example.

[0088] As an example, the stage 2 is moved along the X direction, thereby relatively moving the condensing point C along the X direction with respect to the object 11, to form a plurality of modified points 12s in a line along the X direction. One modified point 12s is formed by irradiation of one pulse of the laser L. One line of modified regions 12 is a collection of a plurality of modified points 12s arranged in a line. Therefore, like the modified region 12, the modified point 12s is a point whose density, refractive index, mechanical strength, other physical characteristics are different from those of the surrounding non-modified portion. Depending on the relative moving speed of the condensing point C with respect to the object 11 and the repetition frequency of the laser L, there are cases where adjacent modified points 12s are connected to each other and cases where they are separated from each other.

[0089] More specifically, 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 unit 7 and the imaging unit 8 image the object 11 supported by the stage 2 by light that penetrates the object 11 in accordance with the control of the control section 10. The images obtained by the imaging by the imaging units 7, 8 are used as an example for the alignment of the irradiation position of the laser L.

[0090] The drive unit 9 supports the laser irradiation unit 3 and the plurality of imaging units 4, 7, 8. The drive unit 9 moves the laser irradiation unit 3 and the plurality of imaging units 4, 7, 8 in the Z direction.

[0091] 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, and a communication device. In the processing section 101, the processor executes software (program) read by the memory, reads or writes data to or from the memory and the storage, and controls communication 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 constitutes a GUI (Graphical User Interface).

[0092] [Structure of Object]

[0093] Figure 2 is a plan view of a wafer of the embodiment. Figure 3 is a cross-sectional view of a portion of the wafer shown in Figure 2 . An example of the object 11 of the present embodiment is Figure 2 , Figure 3 wafer 20 shown in FIG. 2. The wafer 20 includes a semiconductor substrate 21 and a functional element layer 22. The semiconductor substrate 21 has a front surface 21a and a back surface 21b. As an example, the back surface 21b is a first surface that becomes an incident surface of the laser L or the like, and the front 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 front surface 21a of the semiconductor substrate 21. The functional element layer 22 includes a plurality of functional elements 22a arranged in a two-dimensional manner along the front surface 21a.

[0094] Functional elements 22a may be, for example, light-receiving elements such as photodiodes, light-emitting elements such as laser diodes, or circuit elements such as memory. Functional elements 22a may also be constructed in a three-dimensional manner by stacking multiple layers. Furthermore, trenches 21c indicating the crystal orientation are provided on the semiconductor substrate 21; however, orientation planes may be provided instead of trenches 21c. Additionally, the object 11 may be a bare wafer.

[0095] The wafer 20 is diced into individual functional elements 22a along a plurality of lines 15. Viewed from the thickness direction of the wafer 20, the plurality of lines 15 pass between the individual functional elements 22a. More specifically, viewed from the thickness direction of the wafer 20, the plurality of lines 15 pass through the center (center in the width direction) of a grid line region 23. The grid line region 23 extends in the functional element layer 22 in a manner that passes between adjacent functional elements 22a. In this embodiment, the plurality of functional elements 22a are arranged in a matrix shape along the surface 21a, and the plurality of lines 15 are set in a grid shape. Furthermore, although the lines 15 are imaginary lines, they could also be actually drawn lines.

[0096] [Structure of the laser irradiation unit]

[0097] 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 instead, laser light L is introduced from outside the laser irradiation unit 3.

[0098] 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 disposed in the optical path of the laser L from the spatial light modulator 5 to the condenser lens 33. The pair of lenses 34A and 34B constitute a bilateral telecentric optical system in which the reflecting surface 5a of the spatial light modulator 5 and the entrance pupil surface (pupil surface) 33a of the condenser lens 33 are in 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.

[0099] The spatial light modulator 5 is a reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM). The spatial light modulator 5 is configured by sequentially stacking a drive 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.

[0100] The semiconductor substrate 51 is, for example, a silicon substrate. The drive circuit layer 52 configures 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 a surface of the semiconductor substrate 51. Each pixel electrode 53a is formed of, for example, a metal material such as aluminum. Each pixel electrode 53a is applied with a voltage by the drive circuit layer 52.

[0101] The reflective film 54 is, for example, a dielectric multilayer film. The alignment film 55 is provided on a surface of the liquid crystal layer 56 on the reflective film 54 side, and the alignment film 57 is provided on a surface of the liquid crystal layer 56 on the opposite side from the reflective film 54. Each of the alignment films 55 and 57 is formed of, for example, a high molecular material such as polyimide, and a contact surface of each of the alignment films 55 and 57 with the liquid crystal layer 56 is subjected to rubbing treatment. The alignment films 55 and 57 align liquid crystal molecules 56a included in the liquid crystal layer 56 in a prescribed direction.

[0102] The transparent conductive film 58 is provided on a surface of the transparent substrate 59 on the alignment film 57 side, and opposes the pixel electrode layer 53 via the liquid crystal layer 56 and the like. 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.

[0103] In the spatial light modulator 5 configured in the above-described manner, when a signal indicating 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 the 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 the liquid crystal layer 56 displays the modulation pattern.

[0104] In a state where the liquid crystal layer 56 displays a modulation pattern, 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 on the liquid crystal layer 56. Thus, by appropriately setting the modulation pattern displayed on the liquid crystal layer 56 by the spatial light modulator 5, modulation of the laser light L (for example, modulation of the intensity, amplitude, phase, polarization, or the like of the laser light L) can be performed.

[0105] In the present embodiment, the laser light irradiation unit 3 respectively irradiates laser light L along the plurality of lines 15 from the back surface 21b side of the semiconductor substrate 21 to the wafer 20, thereby respectively forming two rows of modified regions 12a, 12b inside the semiconductor substrate 21 along the plurality of lines 15. The modified region (first modified region) 12a is a modified region closest to the surface 21a among the two rows of modified regions 12a, 12b. The modified region (second modified region) 12b is a modified region closest to the modified region 12a among the two rows of modified regions 12a, 12b, and is a modified region closest to the back surface 21b.

[0106] The two rows of modified regions 12a, 12b are adjacent in the thickness direction (Z direction) of the wafer 20. The two rows of modified regions 12a, 12b are formed by relatively moving the two focal points O1, O2 along the line 15 to the semiconductor substrate 21. The laser light L is modulated by the spatial light modulator 5 to be, for example, on the rear side of the traveling direction with respect to the focal point O1 and on the incident side of the laser light L.

[0107] As an example, the laser light irradiation unit 3 can irradiate laser light L along the plurality of lines 15 from the back surface 21b side of the semiconductor substrate 21 to the wafer 20 in a condition in which a crack 14 that crosses the two rows of modified regions 12a, 12b reaches the surface 21a of the semiconductor substrate 21. As an example, with respect to a single-crystal silicon substrate, that is, the semiconductor substrate 21, having a thickness of 775 μm, the two focal points O1, O2 are respectively focused at positions 54 μm and 128 μm from the surface 21a, and laser light L is irradiated along the plurality of lines 15 from the back surface 21b side of the semiconductor substrate 21 to the wafer 20.

[0108] At this time, the wavelength of the laser light L is 1099 nm, the pulse width is 700 nsec, and the repetition frequency is 120 kHz. Also, the output of the laser light L of the focal point O1 is 2.7 W, the output of the laser light L of the focal point O2 is 2.7 W, and the relative movement speed of the two focal points O1, O2 to the semiconductor substrate 21 is 800 mm / sec.

[0109] Such formation of the two rows of modification regions 12a, 12b and the cracks 14 is performed in a case where, in a later 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, so that the wafer 20 is cut into a plurality of semiconductor devices along the plurality of lines 15, respectively. However, as described below, the laser irradiation unit 3 can also be configured to form the modification regions (modification points) 12a, 12b and the cracks 14 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 14 do not reach the outer surfaces (the front surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0110] [Structure of imaging unit]

[0111] 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 II that is transmissive to the wafer 20 (at least to the semiconductor substrate 21). The light source 41 is configured, for example, by a halogen lamp and a filter, and outputs light II in the near-infrared region. The light II output from the light source 41 is reflected by the mirror 42 and passes through the objective lens 43, so as to be irradiated on the wafer 20 from the back surface 21b side of the semiconductor substrate 21. At this time, as described above, the stage 2 supports the wafer 20 on which the two rows of modification regions 12a, 12b are formed.

[0112] The objective lens 43 passes the light II reflected by the front surface 21a of the semiconductor substrate 21. That is, the objective lens 43 passes the light II 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 II 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 II that has passed through the objective lens 43 and the mirror 42. The light detection section 44 is configured, for example, by an infrared camera including an InGaAs camera, and detects the light II in the near-infrared region. That is, the imaging unit 4 is a means for imaging the semiconductor substrate 21 by the light II that is transmissive to the semiconductor substrate 21. In addition, as a structure for correcting aberration of the light II, the spatial light modulator 5 or other structures can be adopted instead of or in addition to the above-described correction ring 43a. Furthermore, the light detection section 44 is not limited to the InGaAs camera, and can be any imaging device that utilizes transmission-type imaging, such as a transmission-type confocal microscope.

[0113] The imaging unit 4 can image each of the two rows of modified regions 12a, 12b, and the leading ends of each of the plurality of cracks 14a, 14b, 14c, 14d (details will be described later). The crack 14a is a crack extending from the modified region 12a toward the surface 21a side. The crack 14b is a crack extending from the modified region 12a toward the back surface 21b side. The crack 14c is a crack extending from the modified region 12b toward the surface 21a side. The crack 14d is a crack extending from the modified region 12b toward the back surface 21b side.

[0114] That is, the cracks 14b, 14d are first cracks extending from the modified regions 12a, 12b toward the first surface, that is, the back surface 21b side, and the cracks 14a, 14c are second cracks extending from the modified regions 12a, 12b toward the second surface, that is, the surface 21a side. Hereinafter, with the case where the positive direction of the Z direction is upward, the crack 14d among the first cracks will be sometimes referred to as an upper crack, and the crack 14a among the second cracks will be sometimes referred to as a lower crack.

[0115] [Structure of imaging unit for alignment correction]

[0116] 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 detecting 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 be shared with 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 thus is irradiated on the wafer 20 from the back surface 21b side of the semiconductor substrate 21.

[0117] 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 detecting section 74 detects the light I2 passing through the lens 73 and the mirror 72. The light detecting section 74 is constituted by, for example, an infrared camera including an InGaAs camera, and detects the light I2 in the near-infrared region.

[0118] Under the control of the control unit 10, the imaging unit 7 illuminates the wafer 20 with light I2 from the back side 21b and detects the light I2 returning from the surface 21a (functional element layer 22), thereby capturing an image of the functional element layer 22. Similarly, under the control of the control unit 10, the imaging unit 7 illuminates the wafer 20 with light I2 from the back side 21b and detects the light I2 returning from the formation locations of the modified regions 12a and 12b of the semiconductor substrate 21, thereby acquiring an image of the region including the modified regions 12a and 12b. These images are used for aligning the irradiation position of the laser L. The imaging unit 8 has the same structure as the imaging unit 7, except that it has a lower magnification than the lens 73 (e.g., 6x in the imaging unit 7 and 1.5x in the imaging unit 8), and is used for alignment in the same way. In addition, camera units 4, 7, and 8 can also be shared between the camera used to obtain the formation state as described later and the camera used for alignment as described above.

[0119] [The camera unit's camera principle]

[0120] like Figure 9 As shown, using the imaging unit 4, for the semiconductor substrate 21 that spans the crack 14 (extending from the modified point) across two rows of modified regions 12a, 12b and reaches the surface 21a, the focal point F (the focal point of the objective lens 43) is moved from the back surface 21b side to the surface 21a side. In this case, if the focal point F is focused from the back surface 21b side on the tip 14e of the crack 14 extending from the modified region 12b to the back surface 21b side, it is possible to confirm that the tip 14e (… Figure 9 (Image on the right). However, even when focusing F on the crack 14 itself and the tip 14e of the crack 14 reaching the surface 21a from the back side 21b, it cannot be confirmed ( Figure 9 (Image on the left). Additionally, if the focus F is focused on the surface 21a of the semiconductor substrate 21 from the back side 21b, the functional element layer 22 can be identified.

[0121] And, as Figure 10 As shown, using the camera unit 4, for the semiconductor substrate 21 where the crack 14 spanning the two rows of modified regions 12a and 12b does not reach the surface 21a, the focus F is moved from the back side 21b to the surface 21a side. In this case, even if the focus F is focused from the back side 21b on the tip 14e of the crack 14 extending from the modified region 12a to the surface 21a side, the tip 14e cannot be confirmed. Figure 10the right side of (a) of FIG. 10). However, if the focus F is focused on the region on the opposite side with respect to 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) from the back surface 21b side, and the virtual focus Fv symmetrical with respect to the surface 21a from the focus F is located at the tip 14e, it is confirmed that the tip 14e (the image on the right side of (b) of FIG. 10) is black. In addition, the virtual focus Fv is a point symmetrical with respect to the surface 21a from the focus F, in which the refractive index of the semiconductor substrate 21 has been taken into account. Figure 10

[0122] It is presumed that the reason why the crack 14 cannot be confirmed as described above is because the width of the crack 14 is smaller than the wavelength of the light I1 as the illumination light. Figure 11 Figure 12 are SEM (Scanning Electron Microscope) images of the modified region 12 and the crack 14 formed in the inside of the silicon substrate, i.e., the semiconductor substrate 21. Figure 11 (b) of FIG. 9 is an enlarged image of the region A1 shown in (a) of FIG. 9, Figure 11 (a) of FIG. 9 is an enlarged image of the region A1 shown in (a) of FIG. 9, Figure 12 (b) of FIG. 10 is an enlarged image of the region A2 shown in (a) of FIG. 10, Figure 11 (a) of FIG. 10 is an enlarged image of the region A2 shown in (a) of FIG. 10, Figure 12 (b) of FIG. 11 is an enlarged image of the region A3 shown in (a) of FIG. 11. Figure 12 (b) of FIG. 11 is an enlarged image of the region A3 shown in (a) of FIG. 11. Thus, the width of the crack 14 is about 120 nm, which is smaller than the wavelength of the light I1 in the near-infrared region (e.g., 1.1 to 1.2 μm).

[0123] The imaging principle based on the above assumption is described below. As shown in (a) of FIG. 10, if the focus F is located in the air, the light I1 does not return, so a black image (the image on the right side of (a) of FIG. 10) is obtained. Figure 13 Figure 13 As shown in (b) of FIG. 10, if the focus F is located in the inside of the semiconductor substrate 21, the light I1 reflected by the surface 21a returns, so a white image (the image on the right side of (b) of FIG. 10) is obtained. Figure 13 Figure 13 As shown in (c) of FIG. 10, if the focus F is focused on the modified region 12 from the back surface 21b side, a part of the light I1 reflected by the surface 21a and returned is absorbed, scattered, or the like by the modified region 12, so an image in which the modified region 12 appears black on a white background (the image on the right side of (c) of FIG. 10) is obtained. Figure 13 Figure 13 As shown in (c) of FIG. 10, if the focus F is focused on the modified region 12 from the back surface 21b side, a part of the light I1 reflected by the surface 21a and returned is absorbed, scattered, or the like by the modified region 12, so an image in which the modified region 12 appears black on a white background (the image on the right side of (c) of FIG. 10) is obtained.

[0124] As shown in (c) of FIG. 10, if the focus F is focused on the modified region 12 from the back surface 21b side, a part of the light I1 reflected by the surface 21a and returned is absorbed, scattered, or the like by the modified region 12, so an image in which the modified region 12 appears black on a white background (the image on the right side of (c) of FIG. 10) is obtained. Figure 14 ​​​​​If the focal point F is focused to the front end 14e of the crack 14 from the back surface 21b side as shown in (a) and (b) of the drawing, for example, the light is confined in the vicinity of the front end 14e due to optical specificity (stress concentration, distortion, discontinuity of atomic density, etc.) generated in the vicinity of the front end 14e, so a part of the light I1 reflected by the surface 21a returns, thereby causing scattering, reflection, interference, absorption, etc., so an image in which the front end 14e appears black against a white background is obtained (image on the right side of (a) and (b) of the drawing). Figure 14 As shown in (c) of the drawing, if the focal point F is focused to a portion other than the vicinity of the front end 14e of the crack 14 from the back surface 21b side, at least a part of the light I1 reflected by the surface 21a returns, so a white image is obtained (image on the right side of (c) of the drawing). Figure 14 Figure 14

[0125] [Principle of inspection of imaging unit]

[0126] The control section 10 causes the laser irradiation unit 3 to irradiate the laser L under conditions in which the crack 14 that crosses the modified regions 12a, 12b of two rows reaches the surface 21a of the semiconductor substrate 21, so that, as intended, when the crack 14 that crosses the modified regions 12a, 12b of two rows reaches the surface 21a, the state of the front end 14e of the crack 14 becomes the following state. That is, as shown in (a) of the drawing, the front end 14e of the crack 14 does not appear in the region between the modified region 12a and the surface 21a, and in the region between the modified region 12a and the modified region 12b. The position of the front end 14e of the crack 14 that extends from the modified region 12b toward the back surface 21b side (hereinafter referred to as "front end position") is located on the back surface 21b side with respect to the reference position P between the modified region 12b and the back surface 21b. Figure 15 In contrast, the control section 10, in the case where the crack 14 that crosses the modified regions 12a, 12b of two rows does not reach the surface 21a, the state of the front end 14e of the crack 14 becomes the following. That is, as shown in (b) of the drawing, the front end 14e of the crack 14a that extends from the modified region 12a toward the surface 21a side appears in the region between the modified region 12a and the surface 21a. In the region between the modified region 12a and the modified region 12b, the front end 14e of the crack 14b that extends from the modified region 12a toward the back surface 21b side, and the front end 14e of the crack 14c that extends from the modified region 12b toward the surface 21a side appear. The front end position of the crack 14 that extends from the modified region 12b toward the back surface 21b side is located on the surface 21a side with respect to the reference position P between the modified region 12b and the back surface 21b.

[0127] Figure 16

[0128] ​​​​As described above, by causing the control section 10 to perform at least one of the following first check, second check, third check, and fourth check, it is possible to evaluate whether or not the cracks 14 that span the modification regions 12a and 12b have reached the surface 21a of the semiconductor substrate 21. The first check is a check that determines whether or not the leading end 14e of the crack 14a that extends from the modification region 12a toward the surface 21a side is present in a region between the modification region 12a and the surface 21a, which is the check region Rl.

[0129] The second check is a check that determines whether or not the leading end 14e of the crack 14b that extends from the modification region 12a toward the back surface 21b side is present in a region between the modification region 12a and the modification region 12b, which is the check region R2. The third check is a check that determines whether or not the leading end 14e of the crack 14c that extends from the modification region 12b toward the surface 21a side is present in the check region R2. The fourth check is a check that determines whether or not the leading end position of the crack 14 that extends from the modification region 12b toward the back surface 21b side is present in a region that extends from the reference position P toward the back surface 21b side and does not reach the back surface 21b, which is the check region R3.

[0130] In addition, by the above-described checks, it is possible to obtain not only information on whether or not the leading end 14e of the crack 14 is present in a predetermined region, but also information on the formation state of the modification regions and cracks, such as the positions of the respective leading ends 14e, the positions of the modification regions 12a and 12b, the lengths of the cracks 14a to 14d, and the overall length of the cracks 14. As described above, the cracks 14b and 14d are first cracks that extend toward the first surface, i.e., the back surface 21b side, and their leading ends 14e are the leading ends on the back surface 21b side, i.e., the first ends, of the first cracks. In particular, the crack 14d is an upper crack. Also, the cracks 14a and 14c are second cracks that extend toward the second surface, i.e., the surface 21a side, and their leading ends 14e are the leading ends on the surface 21a side, i.e., the second ends, of the second cracks. In particular, the crack 14a is a lower crack.

[0131] [Method of obtaining formation state]

[0132] Next, a method of obtaining information on the formation state of the modification regions and cracks will be described. Figure 17 is a cross-sectional view of an object to which the method of obtaining the formation state is applied. Figure 17 In Figure 17In the middle, a virtual image 12aI, a virtual image 12bI, a virtual image 14aI, a virtual image 14bI, a virtual image 14cI, and a virtual image 14dI of a position symmetrical with respect to the surface 21a are illustrated for each of the modified region 12a, the modified region 12b, the crack 14a, the crack 14b, the crack 14d, the crack 14c, and the crack 14d.

[0133] Also, in Figure 17 In the middle, a virtual image 12aI, a virtual image 12bI, a virtual image 14aI, a virtual image 14bI, a virtual image 14cI, and a virtual image 14dI of a position symmetrical with respect to the surface 21a are illustrated for each of the modified region 12a, the modified region 12b, the crack 14a, the crack 14b, the crack 14d, the crack 14c, and the crack 14d.

[0134] In the wafer 20, the modified regions 12a and 12b, the crack 14a (lower crack) extending from the modified region 12a to the surface 21a side, the crack 14b extending from the modified region 12a to the back surface 21b side, the crack 14c extending from the modified region 12b to the surface 21a side, and the crack 14d (upper crack) extending from the modified region 12b to the back surface 21b side are formed in such a manner that they do not reach the outer surfaces (the surface 21a and the back surface 21b).

[0135] In addition, in Figure 17 In the example of the middle, the crack 14b and the crack 14c are connected to each other to form a single crack, but there are cases in which they are separated from each other. Also, the front end 14e of the crack 14d (upper crack) on the back surface 21b side is sometimes referred to as a first end (upper crack front end) 14de, and the front end 14e of the crack 14a (lower crack) on the surface 21a side is sometimes referred to as a second end (lower crack front end) 14ae.

[0136] The formation state of the modified 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 described below is one example of a first direction intersecting (orthogonal to) the surface 21a and the back surface 21b. Also, for each of the formation state items described below, a symbol not illustrated is labeled for the purpose of facilitating the description. Also, each value is a value with the surface 21a as a reference position (0 point).

[0137] Upper crack front end position F1: a position of the first end 14de in the Z direction.

[0138] Upper crack amount F2: a length of the crack 14d in the Z direction.

[0139] Lower crack tip position F3: a position of the second end 14ae in the Z direction.

[0140] Lower crack amount F4: a length of the crack 14a in the Z direction.

[0141] Total crack amount F5: a total amount of lengths of the cracks 14a to 14d in the Z direction, and is a distance between the first end 14de and the second end 14ae in the Z direction.

[0142] Upper and lower crack tip position deviation width F6: a deviation width of a position of the first end 14de and a position of the second end 14ae in a direction (Y direction) intersecting (orthogonal to) the processing travel direction (X direction).

[0143] Presence or absence of modified region scratch F7: presence or absence of a scratch of a modified point constituting each modified region 12a, 12b.

[0144] Lower crack tip meandering amount F8: a meandering amount of the second end 14ae in the Y direction.

[0145] Presence or absence of black line between modified regions F9: presence or absence of a front end of the crack 14b on the back surface 21b side and a front end of the crack 14c on the surface 21a side of a region between the modified region 12a and the modified region 12b (whether the crack 14b and the crack 14c are connected). When the front ends of the cracks 14b, 14c are present, a black line is observed (corresponding to "black line is present"); when the front ends of the cracks 14b, 14c are not present (connected), a black line is not observed (corresponding to "black line is not present").

[0146] In order to obtain the formation state including the above formation state items, the following imaging C1 to C11 can be performed by the light I1 of the imaging unit 4.

[0147] 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 focused on the first end 14de of the crack 14d. At this time, a position in the Z direction to which the focal point F is focused (a position with the back surface 21b as a reference) can be obtained as the position P1.

[0148] Imaging C2: the semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F is focused on the front end on the back surface 21b side of the modified region 12b. At this time, a position in the Z direction to which the focal point F is focused (a position with the back surface 21b as a reference) can be obtained as the position P2.

[0149] Imaging C3: The semiconductor substrate 21 is imaged by the light I1 in such a manner that the focus point F is focused on the front end of the back surface 21b side of the crack 14b. At this time, the position in the Z direction to which the focus point F is focused (the position with the back surface 21b as a reference) can be acquired as the position P3.

[0150] Imaging C4: The semiconductor substrate 21 is imaged by the light I1 in such a manner that the focus point F is focused on the front end of the back surface 21b side of the modified region 12a. At this time, the position in the Z direction to which the focus point F is focused (the position with the back surface 21b as a reference) can be acquired as the position P4.

[0151] Imaging C5: The semiconductor substrate 21 is imaged by the light I1 in such a manner that the focus point F is focused on the second end 14ae of the crack 14a from the surface 21a side (in such a manner that the focus point F is focused on the front end of the virtual image 14al). At this time, the position in the Z direction to which the focus point F is focused (the position with the back surface 21b as a reference) can be acquired as the position P5l. The position P5l is a position corresponding to the front end of the virtual image 14al, and thus is a position outside the semiconductor substrate 21 (a position on the lower side than the surface 21a). Furthermore, the position P5 of the second end 14ae of the crack 14a (the real image) can be acquired by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P5l.

[0152] Imaging C6: The semiconductor substrate 21 is imaged by the light I1 in such a manner that the focus point F is focused on the front end of the surface 21a side of the modified region 12a from the surface 21a side (in such a manner that the focus point F is focused on the front end of the virtual image 12al). At this time, the position in the Z direction to which the focus point F is focused (the position with the back surface 21b as a reference) can be acquired as the position P6l. The position P6l is a position corresponding to the front end of the virtual image 12al, and thus is a position outside the semiconductor substrate 21 (a position on the lower side than the surface 21a). Furthermore, the position P6 of the front end of the modified region 12a (the real image) can be acquired by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P6l. Furthermore, the position P6 can also be acquired by multiplying the Z height by the DZ rate, where the Z height is the amount of movement in the Z direction of the objective lens 43 when the modified region 12a is formed, and the DZ rate is a coefficient for taking into account the refractive index of the material (for example, silicon) of the semiconductor substrate 21.

[0153] Imaging C7: The semiconductor substrate 21 is imaged by the light I1 while the focus point F is scanned in the range P7 between the position P1 and the position P2.

[0154] Imaging C8: The semiconductor substrate 21 is imaged by the light I1 while the focus point F is scanned in the range P8 between the position P5 and the position P6.

[0155] Imaging C9: The semiconductor substrate 21 is imaged by the light I1 while the focal point F is scanned in a range P9 between the modified region 12a and the modified region 12b.

[0156] Imaging C10: The semiconductor substrate 21 is imaged by the light I1 while the focal point F is scanned in a range P10 across the front end of the modified region 12a on the back surface 21b side.

[0157] Imaging C11: The semiconductor substrate 21 is imaged by the light I1 in such a manner that the focal point F is focused on the front end of the modified region 12b on the surface 21a side from the surface 21a side (in such a manner that the focal point F is focused on the front end of the virtual image 12bI). At this time, the position in the Z direction to which the focal point F is focused (the position with the back surface 21b as a reference) is acquired as a 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). Furthermore, 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. Alternatively, the position P11 can be acquired by multiplying a Z height by a DZ rate, where the Z height is the amount of movement in the Z direction of the objective lens 43 when the modified region 12b is formed, and the DZ rate is a coefficient for taking into account the refractive index of the material (e.g., silicon) of the semiconductor substrate 21.

[0158] The above-described respective formation state items are acquired by performing the above-described imaging C1 to C10 as described below.

[0159] Upper crack front position F1: A value (T-P1) obtained by subtracting the distance from the back surface 21b of the position P1 acquired by the imaging C1 from the thickness T of the semiconductor substrate 21 is acquired.

[0160] Upper crack amount F2: A value (P2-P1) obtained by subtracting the distance from the back surface 21b of the position P1 from the distance from the back surface 21b of the position P2 acquired by the imaging C2 is acquired.

[0161] Lower crack front position F3: As described above, a value (P5I-T=P5) obtained by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b of the position P5I acquired by the imaging C5 is acquired.

[0162] Lower crack amount F4: As described above, a value (P5-P6) obtained by subtracting the value (P6I-T=P6) obtained by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b of the position P6I acquired by the imaging C6 from the distance from the back surface 21b of the position P5 is acquired.

[0163] Total crack amount F5: A distance obtained by subtracting the distance from the back surface 21b of the position P1 from the distance from the back surface 21b of the position P5 is acquired.

[0164] Width of deviation of upper and lower crack front positions F6: can be measured from the image taken by imaging C10 at range P10.

[0165] Presence or absence of marking of modified region F7: for the modified region 12b, can be judged from the image taken by imaging C2 at position P2 or the image taken by imaging C11 at position P11 (position P11I); for the modified region 12a, can be judged from the image taken by imaging C4 at position P4 or the image taken by imaging C6 at position P6 (position P6I).

[0166] Amount of meandering of lower crack front F8: can be measured from the image taken by imaging C5 at position P5 (position P5I).

[0167] Presence or absence of black line between modified regions F9: can be judged from the image taken by imaging C9 at range P9 (when the front ends of cracks 14b, 14c are confirmed in the image taken at range P9, it can be judged that there is a black line).

[0168] [Relationship between irradiation conditions and formation state]

[0169] When the irradiation conditions of laser L are changed when the modified regions 12a, 12b are formed, the formation state of the modified regions 12a, 12b and the cracks 14a to 14d can also change. Next, with respect to the correlation between the irradiation conditions of laser L and the formation state of the modified regions 12a, 12b and the cracks 14a to 14d, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 among the formation state items are exemplified.

[0170] First, the irradiation conditions of 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 described below. In addition, for each of the following irradiation condition items, a symbol not shown is indicated for the purpose of facilitating the explanation.

[0171] Modified region interval D1: interval between the modified region 12a and the modified region 12b in the Z direction.

[0172] Pulse width D2: pulse width of laser L.

[0173] Pulse energy D3: pulse energy of laser L.

[0174] Pulse interval D4: pulse interval of laser L.

[0175] Condensing state D5: It is a condensing state of the laser, and one example thereof is a spherical aberration correction level D6, a coma correction level D7, and an LBA deviation amount D8 (to be described later).

[0176] Figure 18 and Figure 19 is a graph showing a change in the amount of cracking in the case where the modified region interval is varied at three points. Figure 18 The horizontal axis of the graph of (a), (b) of indicates the modified region interval D1 by Z height. The three points of the modified region interval D1 are level 4, level 8, and level 12, and each corresponds to Figure 19 (a), (b), and (c) of Figure 19 is a cut surface.

[0177] As shown in Figure 18 and Figure 19 , in the processing of either the forward path or the return path, as the modified region interval D1 increases, the upper cracking amount F2, the lower cracking amount F4, and the total cracking amount F5 also increase. In addition, as one example thereof: a case where the condensing point of the laser L is advanced in the X positive direction (the processing advancement direction is the X positive direction) is referred to as processing on the forward path, and a case where the condensing point of the laser L is advanced in the X negative direction (the processing advancement direction is the X negative direction) is referred to as processing on the return path.

[0178] Figure 20 and Figure 21 is a graph showing a change in the amount of cracking in the case where the pulse width of the laser is varied at three points. The three points of the pulse width D2 are level 2, level 3, and level 5, and each corresponds to Figure 21 (a), (b), and (c) of Figure 21 is a cut surface. As shown in Figure 20 , 21 , as the pulse width D2 increases, the upper cracking amount F2, the lower cracking amount F4, and the total cracking amount F5 also increase. However, in the case where the pulse width D2 is level 2, a black line (there is a black line between the modified regions) is generated between the modified region 12a and the modified region 12b, and thus the total cracking amount F5 cannot be measured by the imaging unit 4 (the total cracking amount F5 is known to be in the region A from the observation of the cut surface).

[0179] Figure 22 and Figure 23 is a graph showing a change in the amount of cracking in the case where the pulse energy of the laser is varied at three points. The three points of the pulse energy D3 are level 2, level 7, and level 12, and each corresponds to Figure 23 (a), (b), and (c) of Figure 23 is a cut surface. As shown in Figure 22 , 23As shown, as the pulse energy D3 increases, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also increase.

[0180] 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 four points. The four points of the pulse interval D4 are level 2.5, level 3.3, level 4.1, and level 6.7, and each corresponds to Figure 24 (a), (b), (c), and (d) of FIG. 4. In addition, Figure 25 is a cut surface. As shown in Figure 24 and Figure 25 As shown, as the pulse interval D4 changes, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also change.

[0181] In particular, among the pulse intervals D4 at the four points, a peak value appears in the lower crack amount F4 on the outbound and return routes, the upper crack amount F2 on the return route, and the total crack amount F5 on the return route. However, in the case where the pulse interval D4 is level 6.7, a black line (black line between the modified regions) is generated between the modified region 12a and the modified region 12b, so that the total crack amount F5 cannot be measured by the imaging unit 4 (the total crack amount F5 is located in the region B from the observation of the cut surface).

[0182] Figure 26 and Figure 27 is a graph showing changes in the crack amount in the case where the condensing state (spherical aberration correction level) of the laser light is changed at three points. The three points of the spherical aberration correction level D6 are level -4, level -10, and level -16, and each corresponds to Figure 27 (a), (b), and (d) of FIG. 6. In addition, Figure 27 is a cut surface. As shown in Figure 26 and Figure 27 As shown, as the spherical aberration correction level D6 increases, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 decrease.

[0183] Figure 28 and Figure 29 is a graph showing changes in the crack amount in the case where the condensing state (astigmatism correction level) of the laser light is changed at three points. The three points of the astigmatism correction level D7 are level 2.5, level 10, and level 17.5, and each corresponds to Figure 28 (a), (b), and (d) of FIG. 8. In addition, Figure 29 is a cut surface. As shown in Figure 28 and Figure 29As shown, the upper crack amount F2, lower crack amount F4, and total crack amount F5 also change with the astigmatism correction level D7. In particular, except for the upper crack amount F2 on the outgoing and returning paths, peak values ​​are observed at the astigmatism correction level D7 at the three points.

[0184] Figure 30 and Figure 31 This diagram illustrates the change in the presence or absence of black lines when the laser pulse spacing is varied at four points. The four points of 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 a 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), a black line Bs can be confirmed to be generated between the modified region 12a and the modified region 12b in the observation of the cut surface.

[0185] 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 modified regions 12a and 12b are formed, by taking pictures with the imaging unit 4 to obtain various items of the formation state, it is possible to determine whether the irradiation conditions of laser L are qualified or to derive the preferred irradiation conditions of laser L.

[0186] [First Embodiment of the Laser Processing Apparatus]

[0187] Next, one embodiment of the laser processing apparatus 1 will be described. Here, an example of the operation for determining whether the irradiation conditions of the laser L are qualified will be described. Figure 32 This is a flowchart illustrating the main steps of the method for determining whether a result is acceptable or not. The following method is a first embodiment of the laser processing method. Here, firstly, the control unit 10 of the laser processing apparatus 1 receives input from the user (step S1). Step S1 will be described in more detail.

[0188] Figure 33 It means Figure 1 A diagram showing an example of an input receiving unit. (As shown) Figure 33As shown in (a), in process S1, firstly, the control unit 10 displays information H1, which guides the user to select whether to perform a machine difference-wafer correction check, and information H2, which guides the user to select the check content, through the control input receiving unit 103. The so-called "machine difference-wafer correction check" refers to a process where, since the irradiation conditions of the laser L used to achieve the required formation state of the modified regions 12a, 12b and cracks 14a-14d vary depending on the machine difference of the laser processing apparatus 1 and the wafer, laser L irradiation (processing) is performed under predetermined irradiation conditions, and the pass / fail status of the irradiation conditions is judged. Furthermore, in the following description, the formation state of the modified regions 12a, 12b and cracks 14a-14d may sometimes be referred to simply as the "formation state," and the irradiation conditions of the laser L may sometimes be referred to simply as the "irradiation conditions."

[0189] Furthermore, information H2, used to guide 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 (here, the back surface 21b) to the front end of the surface 21a side of the modified region 12a. Here, the processing conditions are various conditions under predetermined wafer thickness and processing position that prevent cracks from reaching the outer surface (ST).

[0190] Next, in process S1, the input receiving unit 103 accepts the user's selection regarding whether to perform machine difference-wafer correction inspection. Furthermore, in process S1, the input receiving unit 103 accepts the selection of inspection contents H21 to H24, etc. Then, in process S1, when the input receiving unit 103 accepts the selection to perform machine difference-wafer correction inspection and accepts the selection of inspection contents H21 to H24, etc., the control unit 10 sets the processing conditions (including the irradiation conditions of laser L) corresponding to the inspection contents H21 to H24, etc., as basic processing conditions.

[0191] Figure 34 This is a diagram showing the state of the input receiving unit, illustrating an example of basic processing conditions. (Example) Figure 34 As shown, in process S1, when the input receiving unit 103 accepts the selection to perform machine difference-wafer correction inspection and accepts the selection of inspection contents H21 to H24, the control unit 10 controls the input receiving unit 103 to display information H3 indicating the set basic processing conditions on the input receiving unit 103. The information H3 indicating the basic processing conditions includes multiple items.

[0192] Among the plurality of items, the item H31 indicating the execution of the machine difference-wafer correction inspection, the processing condition H32, the wafer thickness H33, and the processing position H34 first indicate the selection result of the inspection contents H21 to H24 and the like, and currently do not accept the selection from the user. On the other hand, the focal point number H41, the scanning number H42, the processing speed H43, the pulse width H44, the frequency H45, the pulse energy H46, the judgment item H47, the target value H48, and the specification H49 are items of which the control section 10 prompts as an example of the basic processing condition, and currently can accept the selection (change) from the user.

[0193] In addition, the focal point number H41 indicates the branch number (the number of focal points) of the laser L, the scanning number H42 indicates the number of times of scanning of 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 judgment item H47 displays the formation state item for performing the pass / fail judgment of the irradiation condition of the laser L among the plurality of formation state items described above.

[0194] Here, as the judgment item H47, an example is to set the crack amount (lower side), that is, the lower crack amount F4 (other formation state items can also be selected). Also, the target value H48 is a value indicating the center of the pass range of the irradiation condition of the laser L, and the specification H49 is a value indicating the upper and lower width from the center value (target value H48) of the pass range. That is, here, as the basic processing condition, when 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 judged to be a pass (other ranges can also be selected).

[0195] The above is the process S1, and the basic processing condition of the laser processing is set. In the next process, the control section 10 performs the fourth process (process S2), that is, the judgment as to whether the irradiation condition set in the process S1 (that is, the basic processing condition) is actually the condition in which the cracks 14a, 14d do not reach the outer surface (the surface 21a and the back surface 21b) (the non-reach condition (ST condition)). Here, the control section 10 (does not perform imaging) refers to the database to judge whether the accepted input condition is the non-reach condition. As an example, the control section 10 can judge "whether the condensing position of the processing position corresponding to the accepted input becomes the condition in which the crack 14a reaches the surface 21a (BHC condition) and the like due to being too close to the surface 21a".

[0196] In the next process, when the result of the determination of the process S2 is the result indicating that the basic processing condition is the non-reach condition (process S2: YES), processing is performed in accordance with the basic processing condition set in the process S1 (process S3, first process). Here, the control section 10 performs the first processing, that is, by controlling the laser irradiation unit 3 to irradiate the laser L against the semiconductor substrate 21, the modification regions 12a, 12b and the cracks 14a to 14d extending from the modification regions 12a, 12b are formed in the semiconductor substrate 21 in a manner not to reach the outer surfaces (the surface 21a and the back surface 21b) of 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 condensing points Ol, 02 of the laser L along the X direction in a state where the condensing points Ol, 02 are located in the inside of the semiconductor substrate 21. In addition, when the result of the determination of the process S2 is the result indicating that the basic processing condition is not the non-reach condition (process S2: NO), the process returns to the process S1 to set the irradiation condition again.

[0197] Next, the control section 10 performs the second processing (process S4, second process), that is, by controlling the imaging unit 4, the semiconductor substrate 21 is imaged by the light II having the transmittance against the semiconductor substrate 21, thereby acquiring the information indicating the formation state of the modification regions 12a, 12b and / or the cracks 14a to 14b. Here, since the lower crack amount F4 is designated as the determination item H47 in the process S1, 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).

[0198] Next, the control section 10 performs the third processing (process S5, third process), that is, by controlling the input accepting section 103, the information indicating the irradiation condition of the laser L in the process S3 (first processing) and the information indicating the formation state acquired in the process S4 (second processing) are associated with each other, and are displayed in the input accepting section 103. The information indicating the formation state (formation state item) displayed in this process S5 is the lower crack amount F4 of the determination item H47 set in the process S1 (other formation state items can also be displayed). As described above, the determination item H47 can be selected.

[0199] Therefore, in process S1, the control unit 10 performs a fourth process, namely, by controlling the input receiving unit 103, the input receiving unit 103 displays information guiding the selection of the formation state item displayed on the input receiving unit 103 in process S4 from among multiple formation state items. Furthermore, the input receiving unit 103 accepts the selection of the formation state item in process S1. Next, in process S5, the control unit 10, by controlling the input receiving unit 103, establishes a correlation between the information received by the input receiving unit 103 indicating the formation state item (here, the lower crack amount F4) and the information indicating the irradiation conditions of the laser L (here, the pulse energy D3), and displays it on the input receiving unit 103.

[0200] Furthermore, the control unit 10 may perform a seventh process, that is, by controlling the input receiving unit 103, the input receiving unit 103 displays information guiding the selection of the irradiation condition item displayed on the input receiving unit 103 in step S4 from among the items included in the irradiation conditions of the laser L (i.e., multiple irradiation condition items). When performing this seventh process, the input receiving unit 103 may also receive input indicating the selection of an irradiation condition item, and the control unit 10, by controlling the input receiving unit 103, establishes a correlation between the information indicating the irradiation condition item received by the input receiving unit 103 and the information indicating the formation state, and displays this association on the input receiving unit 103.

[0201] In the next process, the control unit 10 performs the following process (process S6): that is, based on the information obtained in process S4 indicating the formation state of the modified regions 12a, 12b and / or cracks 14a to 14b, it judges whether the irradiation conditions of the laser L in process S3 (first process) are qualified. More specifically, the judgment item H47 set in process S1 is the lower crack amount F4, the target value H48 is 40μm, and the specification is ±5μm. Therefore, when the lower crack amount F4 obtained in process S4 is in the range of 35μm to 45μm, the control unit 10 judges the irradiation conditions of the laser L in process S3 as qualified.

[0202] As described above, judgment item H47 can be selected. Therefore, in process S1, the control unit 10 performs the following process: by controlling the input receiving unit 103, information used to guide the selection of the item (i.e., judgment item H47) for pass / fail judgment from among the multiple formation state items included in the formation state is displayed on the input receiving unit 103. Furthermore, the input receiving unit 103 accepts the selection of judgment item H47 in process S1. Next, the control unit 10 performs a pass / fail judgment based on the information indicating judgment item H47 received by the input receiving unit 103.

[0203] And, as described above, the target value H48 and the specification H49 can be selected. Therefore, in the process S1, the control section 10 performs the following processing: that is, by controlling the input accepting section 103, the input accepting section 103 is caused to display information for guiding the input of the target value H48 and the specification H49 of the formation state. And, the input accepting section 103 accepts the input of the target value H48 and the specification H49 in the process S1. And, the control section 10 performs the pass / fail judgment in the process S6 by comparing the formation state (the amount of fine cracks F4) under the irradiation condition of the process S3 with the target value H48 and the specification H49.

[0204] In the case where the result of the process S6 is a result indicating the pass (process S6: YES), the control section 10 performs the judgment of whether or not to end the pass / fail judgment (process S8) after performing the processing of causing the judgment result indicating the pass (the result of the pass / fail judgment) to be displayed on the input accepting section 103 (process S7) by controlling the input accepting section 103. In this process S8, the control section 10 causes the information for guiding the selection of whether or not to end the pass / fail judgment to be displayed on the input accepting section 103 by controlling the input accepting section 103, and in the case where the input accepting section 103 accepts the input of ending the pass / fail judgment (process S8: YES), the processing is ended. On the other hand, in the case where the input accepting section 103 accepts the input of performing the re-judgment without ending the pass / fail judgment in this process S8 (process S8: NO), the processing is shifted to the process S10 described later. This is because, even in the case where the judgment result of the control section 10 is the pass, there are cases where it is desired to set a good condition further away from the fail, and thus it is required to continue the pass / fail judgment.

[0205] On the other hand, in the case where the result of the process S6 is a result indicating the fail (process S6: NO), the control section 10 performs the processing of causing the judgment result indicating the fail (the result of the pass / fail judgment) to be displayed on the input accepting section 103 (process S9) by controlling the input accepting section 103, and performs the re-judgment of performing the correction of at least one of the plurality of irradiation condition items as the correction item and performing the processing after the first processing again.

[0206] The rejudgment will be described in more detail. In a case where the result of the pass / fail judgment in the step S6 is not pass, and in a case where the input of performing the rejudgment is accepted in the step S8, the control section 10 performs the rejudgment by correcting at least one of the plurality of irradiation condition items included in the irradiation condition as the correction item, and performing the process after the first process again, by controlling the input accepting section 103. That is, the case of performing the rejudgment is not limited to the case where the result of the pass / fail judgment is not pass. In other words, the rejudgment is performed here in accordance with the result of the pass / fail judgment in the step S6. In addition, the control section 10 can perform the process of displaying the information of guiding the selection of whether to perform the "rejudgment by correcting at least one of the plurality of irradiation condition items included in the irradiation condition as the correction item" in the input accepting section 103, and perform the rejudgment in a case where the selection of performing the rejudgment is accepted in the input accepting section 103.

[0207] Therefore, first, as shown in Figure 35 the control section 10 performs the process of displaying the information of guiding the selection of the correction item H5 in the input accepting section 103 by controlling the input accepting section 103 (step S10). The correction item H5 can be selected, for example, from the above-mentioned irradiation condition items. In addition, the control section 10 can display the information of guiding the selection of the judgment item H47 and the machining condition H32 in the input accepting section 103 at the same time as the correction item H5. Further, the input accepting section 103 accepts at least the selection of the correction item H5 by the user (step S10).

[0208] Next, as shown in Figure 36 the control section 10 displays the correction item H5 of the selection result accepted by the input accepting section 103 as the setting screen H6 of the variable condition in the input accepting section 103 by controlling the input accepting section 103. An example of the setting screen H6 is a screen in a case where the pulse energy D3 is selected as the correction item H5. Therefore, 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 three points are displayed as the variable point number H62. These items can also be selected (changed) by the user.

[0209] Further, in the setting screen H6, the maximum value is displayed as the adjustment method H63. Therefore, in the following rejudgment, the irradiation (processing) of the laser L of the three different pulse energies D3 within the range of the level 10 is performed, and in the case where the qualified judgment is not received on the plurality of pulse energies D3, the pulse energy D3 in which the maximum lower crack amount F4 is obtained is displayed as the adjustment candidate. Further, in the setting screen H6, the items other than the correction item H5, the judgment item H47, and the wafer thickness H33 can be currently selected by the user. Further, the control section 10 sets the irradiation conditions and the like displayed in the setting screen H6 as the conditions for performing the rejudgment. 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.

[0210] Next, the control section 10 performs the processing according to the conditions displayed in the setting screen H6 (step Sll, first process). That is, in the following processing, the control section 10 corrects the correction item H5 accepted by the input accepting section 103 and performs the rejudgment. In this step Sll, the control section 10 performs the first processing: that is, by controlling the laser irradiation unit 3, the laser L is irradiated to the semiconductor substrate 21, and the modification regions 12a, 12b and the cracks 14a to 14d extending from the modification regions 12a, 12b are formed in the semiconductor substrate 21 in such a manner that the outer surfaces (the surface 21a and the back surface 21b) of the semiconductor substrate 21 are not reached. In particular, in this case, when the pulse energy as the correction item H5 is three different values, the processing is performed for each of the values.

[0211] Next, the control section 10 performs the second processing (step S12, second process): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is imaged with the light II having the transmittance to the semiconductor substrate 21, and thus the information indicating the formation state of the modification regions 12a, 12b and / or the cracks 14a to 14b is acquired. In this case, since the lower crack amount F4 is specified as the judgment item H47 in the step S1 and the step S10 (setting screen H6), at least the imaging C6 capable of acquiring the lower crack amount F4 is performed.

[0212] Next, the control section 10 executes a fifth process (step S13) : that is, it judges whether or not the cracks 14a, 14d have reached the outer surfaces (the front surface 21a and the back surface 21b) based on the information indicating the formation state acquired in the second process (step S12). In this case, in 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 CO, it is judged that the cracks 14a, 14d have reached the outer surfaces, not that they have not reached (ST). Further, in the imaging CO, the back surface 21b is imaged by the light II (refer to Fig. 2). Figure 17 ).

[0213] In the case where the result of the judgment in the step S13 is the result indicating that the cracks 14a, 14d have reached the outer surfaces, that is, in the case where it is not that they have not reached (step S13: NO), in order to re-set the irradiation conditions for the step S10, the processing proceeds to the step S10.

[0214] On the other hand, in the case where the result of the judgment in the step S13 is the result indicating that the cracks 14a, 14d have not reached the outer surfaces, that is, in the case where they have not reached (step S13: YES), the control section 10 executes a third process (step S14, third process) : that is, it causes the input accepting section 103 to display the information indicating the irradiation conditions of the laser L in the first process (step Sll) and the information indicating the formation state acquired in the second process (step S12) to be associated with each other by controlling the input accepting section 103. The formation state item displayed in this step S14 is the lower crack amount F4 which is the judgment item H47 set in the step S10. As described above, the judgment item H47 can be selected.

[0215] Therefore, in the step S10, the control section 10 executes a sixth process: that is, it causes the input accepting section 103 to display the information for guiding the selection of the formation state item displayed in the input accepting section 103 in the step S14 among the plurality of formation state items by controlling the input accepting section 103. Further, the input accepting section 103 accepts the selection of the formation state item in the step S10. Next, in the step S14, the control section 10 causes the input accepting section 103 to display the information indicating the formation state item (in this case, the lower crack amount F4) accepted by the input accepting section 103 and the information indicating the irradiation conditions of the laser L to be associated with each other by controlling the input accepting section 103.

[0216] In the next process, the control section 10 performs the following processing (process S15): that is, it judges whether or not the irradiation conditions of the laser L in the process Sll (first processing) are qualified, based on the information indicating the formation state acquired in the process S12. More specifically, the judgment item H47 set in the process S10 is the lower crack amount F4, the target value H48 is 40 μm, and the specification is ± 5 μm, so when the lower crack amount F4 acquired in the process S12 is in the range of 35 μm or more and 45 μm or less, the control section 10 judges that the irradiation conditions of the laser L in the process Sll are qualified.

[0217] Also, as described above, the target value H48 and the specification H49 can be selected. Therefore, in the process S10, the control section 10 performs the following processing: that is, it displays the information of the target value H48 and the specification H49 for guiding the input of the formation state in the input accepting section 103, by controlling the input accepting section 103. Also, the input accepting section 103 accepts the input of the target value H48 and the specification H49 in the process S10. Also, in the process S15, the control section 10 performs the judgment of qualification or non-qualification by comparing the formation state (lower crack amount F4) under the irradiation conditions of the process Sll with the target value H48 and the specification H49.

[0218] After that, when the result of the process S15 is a result indicating qualification (process S15: YES), the control section 10 displays the information H7 indicating the judgment result in the input accepting section 103 (process S16), by controlling the input accepting section 103, and ends the processing. Figure 37 is a view of the input accepting section indicating the state in which the information indicating the judgment result (qualification) is displayed. As shown in Figure 37 In the information H7 indicating the judgment result, not only the correction item H5, the judgment item H47, and the wafer thickness H33 described above, but also the machining output H72, the qualification or non-qualification judgment H73, the adjustment result H74, the internal observation image H75, and the graph H76 are displayed.

[0219] The machining output H72 is an item for making the pulse energy D3, which is the correction item H5, variable. That is, here, the machining output H72 is made variable at three points, thereby making the pulse energy D3 variable at three points. In the adjustment result H74, of the three points of the machining output H72 (pulse energy), the machining output H72 (pulse energy) for which the lower crack amount F4 is the largest (supposed to be displayed as a peak) is displayed.

[0220] Further, as for the pulse energy D3 which is the irradiation condition item, as described above, it can be made variable by the processing output. As for the processing output, it can be adjusted, for example, by an attenuator or the like, or by the original output-frequency of the laser irradiation unit 3. On the other hand, as for the modification region interval Dl, for example, in a case where a plurality of light condensing points of the laser L are formed due to branching of the laser, it can be made variable by controlling the position in the Z direction of the light condensing point using the spatial light modulator 5. Also, in a case where the light condensing point of the laser L is a single one, by adjusting the position in the Z direction of the laser irradiation unit 3 between a plurality of scans, the modification region interval Dl can be made variable.

[0221] Further, as for the pulse width D2, it can be made variable by switching the setting (combination of the loaded waveform memory-frequency and the original output) of the laser irradiation unit 3, or, in a case where a plurality of light sources 31 are loaded, by switching the light source 31 or the like. Further, as the irradiation condition item, a pulse waveform including the pulse width D2 can be set. In this case, as for the pulse waveform, not only the pulse width D2 is variable, but also the waveform (rectangular wave, Gaussian, burst pulse) or the like can be variable.

[0222] Further, as for the pulse interval D4, it can be made variable by the relative speed of the light condensing point of the laser L (moving speed of the stage 2) or the frequency of the laser L or the like. Further, as for the spherical aberration correction level D6, it can be made variable by the correction ring lens or the modulation pattern. As for the astigmatism correction level D7 (or, the coma aberration correction level), it can be made variable by the adjustment of the optical system or the modulation pattern. Further, as for the LBA deviation amount D8, it can be made variable by controlling the spatial light modulator 5.

[0223] Continuing to refer to Figure 37 The internal observation image H75 shows an image (image taken in the imaging C5) of the state where the focal point F is focused on the second end 14ae (lower crack front end) of each of the cracks 14a (lower cracks) of the 3 processing outputs H72 (pulse energy D3). In the graph H76, the pulse energy D3 is correlated with the lower crack amount F4. That is, here, the control section 10 correlates the information indicating the formation state item (lower crack amount F4) which the input accepting section 103 accepted in the formation state and the correction item H5 (pulse energy D3) among the information indicating the irradiation condition by the control of the input accepting section 103 (graph H76 where the correlation is established) and displays it in the input accepting section 103.

[0224] Further, in the information H7 indicating the judgment result, information H77 is displayed to guide the selection of whether or not to change the correction item to end the adjustment. 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.

[0225] In the next process, the control section 10 judges "whether or not to end the pass / fail judgment" (process S17). In this process S17, the control section 10 displays the information to guide the selection of "whether or not to end the pass / fail judgment" on the input accepting section 103 by controlling the input accepting section 103, and ends the processing in the case where the input accepting section 103 accepts the input to end the pass / fail judgment (process S17: YES). On the other hand, in this process S17, in the case where the input accepting section 103 accepts the input to perform the re-judgment without ending the pass / fail judgment (process S17: NO), the processing shifts to the process S10 described later. This is because, even in the case where the re-judgment result of the control section 10 is pass, there is a case where, for example, it is intended to set a good condition further away from the failure, and thus it is required to continue the pass / fail judgment.

[0226] On the other hand, in the case where the result of the process S15 is the result indicating the failure (process S15: NO), the control section 10 displays the judgment result (the result of the pass / fail judgment) indicating the failure on the input accepting section 103 by controlling the input accepting section 103 (process S18), and shifts to the process S10. Figure 38 is a view of the input accepting section indicating the state where the information indicating the judgment result (failure) is displayed. As shown in Figure 38 , the information H8 indicating the judgment result is different from the information H7 shown in Figure 37 in that "failure" is displayed in the pass / fail judgment H73, "adjustment impossible" is displayed in the adjustment result H74, and the contents of the graph H76 are different. Further, in the information H8 indicating the judgment result, information H81 is displayed to guide the selection of whether or not to perform the re-adjustment. Thus, the user can avoid the case where the processing shifts to the process S10 and the re-judgment is repeated as described above, and thus the processing ends.

[0227] Further, in the above-described first embodiment, the amount of the undercut F4 is exemplified as the formation state item, and the pulse energy D3 is exemplified as the irradiation condition item (correction item). However, as the irradiation condition item (correction item), any of the above-described items can be selected; as the formation state item, any of the items having the correlation (in this case, the pass / fail judgment usable for the irradiation condition item) with the selected irradiation condition item (correction item) can be selected.

[0228] For example, even if any one of the modification region interval D1 to the condensing state D5 is selected as the irradiation condition item (the correction item), the upper crack front position F1 to the total crack amount F5, the meandering amount of the lower crack front F8, and the presence or absence of the black line between the modification regions F9 can be selected as the formation state item (correlation). Also, in the case where the condensing state D5 is selected as the irradiation condition item (the correction item), the upper and lower crack front position deviation width F6 and the presence or absence of the modification region scratch F7 can be further selected as the formation state item. In this regard, the same is true in other embodiments.

[0229] [Second Embodiment of Laser Processing Apparatus]

[0230] Next, another embodiment of the laser processing apparatus 1 will be described. Here, an 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 procedures of the derivation method of the irradiation condition. The following method is the second embodiment of the laser processing method. Here, first, the control section 10 of the laser processing apparatus 1 accepts input from the user (procedure S21). This procedure S21 will be described in more detail.

[0231] As shown in Figure 40 , in this procedure S21, first, the control section 10 causes the input accepting section 103 to display, by controlling the input accepting section 103, the information J1 to guide the user to select whether or not to perform parameter management, the information J2 to guide the user to select the variable item, the information J3 to guide the user to select the judgment item, and the information J4 to indicate that the selection of the processing condition is automatic. The parameter management is, for example, a mode in which, for an object whose irradiation condition (parameter) to obtain a desired formation state is unknown, the irradiation condition is derived.

[0232] Therefore, in the present embodiment, as will be described later, the laser L is irradiated on the semiconductor substrate 21 along a plurality of lines 15 respectively with mutually different irradiation conditions, thereby forming the modification regions 12a, 12b, and the like. The variable item indicates the irradiation condition item that is different for each of the lines 15 among the irradiation conditions. Also, the judgment item is the item among the formation state items that judges (evaluates) the variable item. Here, the processing condition is various conditions in which the crack does not reach the outer surface (ST).

[0233] Next, in the process S21, the input accepting section 103 accepts the selection made by the user regarding whether to execute the parameter management, and regarding the variable items and the judgment items. Next, in the case where the execution of the parameter management is selected, and the selection of the variable items and the selection of the judgment items are made, the control section 10 automatically selects an example of the processing conditions, and displays information indicating the selected processing conditions on the input accepting section 103.

[0234] Figure 41 is a view of the input accepting section indicating the state where an example of the selected processing conditions is displayed. As shown in Figure 41 , the information J5 indicating the processing conditions is displayed on the input accepting section 103 to prompt the user. The information J5 indicating the processing conditions includes a plurality of items. Among the plurality of items, the item J51 indicating the execution of the parameter management, the variable items J52, and the judgment items J53 are items indicating the results of the previous selections, and are not items currently accepting the selection from the user (the same applies to the wafer thickness J54).

[0235] On the other hand, with respect to the number of focal points J55, the number of scans J56, the processing speed J57, the pulse width J58, the frequency J59, and the ZH (Z height: processing position in the Z direction) J60, the control section 10 prompts an example, and accepts the selection (change) 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 .

[0236] Also, in this example, the pulse energy D3 is selected as the variable item. Therefore, the pulse energy J61 is displayed as the variable condition. Here, the initial value is displayed as the pulse energy J61, and the range of levels 1 to 12 is displayed as the variable range J62. Also, three points are displayed as the variable point number J63. This means that the number of lines 15 different in the irradiation conditions is three. With respect to these items, the selection (change) by the user is currently possible.

[0237] In the next process, the fourth processing (process S22) is executed: that is, a judgment is made as to whether the irradiation conditions set in the process S21 are actually the conditions not reaching the outer surface of the cracks 14a, 14d, that is, the non-reach conditions. Here, as in the above process S2, the control section 10 can judge whether the inputted conditions are the non-reach conditions.

[0238] In the next process, in the case where the result of the judgment in the process S22 indicates that the irradiation condition set in the process S21 is the result of the non-arrival condition (process S22: YES), as described above, the processing is performed in accordance with the information J5 indicated by the processing condition (process S23). That is, in this case, the control section 10 performs the first processing (process S23, first process): that is, the laser L is irradiated onto the semiconductor substrate 21 along the plurality of lines 15 respectively, and the modified regions 12a, 12b, etc. are formed in the semiconductor substrate 21 in such a manner that the outer surfaces (the surface 21a and the back surface 21b) of the semiconductor substrate 21 are not reached.

[0239] In particular, in this process S23, the laser L is irradiated onto the semiconductor substrate 21 with mutually different irradiation conditions for the plurality of lines 15 respectively. As an example, in this case, the pulse energy D3 is changed between the level 1 and the level 12 at three points (3 lines 15) as prompted by the information J5 indicated by the processing condition, and the irradiation of the laser L is performed. Thereby, the modified regions 12a, 12b, etc. having different formation states are formed on the respective lines 15. In addition, in the case where the result of the judgment in the process S22 indicates that the irradiation condition is not the result of the non-arrival condition (process S22: NO), the irradiation condition is set again in the process S21.

[0240] Next, the control section 10 performs the second processing (process S24, second process): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is imaged by the light II having the transmittance with respect to the semiconductor substrate 21, and thereby the information indicating the formation states of the modified regions 12a, 12b and / or the cracks 14a to 14b is acquired. In particular, in this process S23, the information indicating the formation states is acquired for the plurality of lines 15 respectively. In this case, since the lower crack amount F4 is designated as the judgment item J53 in the process S21, 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).

[0241] Next, the control section 10 displays the information indicating the processing result on the input accepting section 103 by controlling the input accepting section 103 (process S25, third process). Figure 42 is a view of the input accepting section indicating the state where the information indicating the processing result is displayed. As shown in Figure 42 , the information indicating the processing result J7 is displayed in the process S25. In the information indicating the processing result J7, not only the above-described variable item J52, the judgment item J53, and the wafer thickness J54, but also the pulse energy J72, the result display J73, the internal observation image J74, and the graph J75 are displayed.

[0242] The pulse energy J72 is an item indicating a variable value of the pulse energy as the variable item J52. That is, in this case, the pulse energy D3 is made different at the three points shown. The internal observation image J74 shows an image (image taken in the photographing C5) of the state in which the focal point F is focused on the second end 14ae (lower crack tip) of each of the cracks 14a (lower cracks) of the three processing outputs (pulse energies D3). The pulse energy D3 is made different at the three points shown.

[0243] The relationship between the pulse energy D3 and the lower crack amount F4 is shown in the graph J75. That is, in this process S25, the control section 10 performs a third process of associating (graph J75 in which the association is made) and displaying, by controlling the input accepting section 103, the information indicating the irradiation conditions of the laser L in the process S23 (first process) and the information indicating the formation state taken in the process S24 (second process) with each other on the input accepting section 103.

[0244] Also, the information indicating the formation state (formation state item) displayed in this process S25 is the lower crack amount F4 of the judgment item J53 set in the process S21. As described above, the judgment item J53 can be selected. Therefore, in the process S21, the control section 10 performs a sixth process of causing the input accepting section 103 to display information for guiding the selection of the formation state item displayed on the input accepting section 103 in the process S25 among the plurality of formation state items by controlling the input accepting section 103.

[0245] Also, the input accepting section 103 accepts the selection of the formation state item in the process S21. Next, in the process S25, the control section 10 causes the input accepting section 103 to associate and display, by controlling the input accepting section 103, the information indicating the formation state item (in this case, the lower crack amount F4) accepted by the input accepting section 103 and the information indicating the irradiation conditions of the laser L (in this case, the pulse energy D3) with each other on the input accepting section 103.

[0246] Likewise, in the process S21, the control section 10 performs the following processing: that is, by controlling the input accepting section 103, the input accepting section 103 displays information for guiding the selection of "the irradiation condition item (which is the variable item that differs for each line 15) displayed in the input accepting section 103 in the process S25" among "the plurality of irradiation condition items included in the irradiation condition of the laser L". Further, the input accepting section 103 accepts the input of the selection of the irradiation condition item (variable item), and the control section 10 controls the laser irradiation unit 3 so as to perform the process S23 in a manner that the variable item (here, the pulse energy D3) accepted by the input accepting section 103 differs for each line 15, and the control section 10 controls the input accepting section 103 so as to display the information indicating the variable item (here, the pulse energy D3) accepted by the input accepting section 103 among the irradiation conditions in association with the information indicating the formation state (here, the lower crack amount F4) in the input accepting section 103.

[0247] In particular, as shown in the graph J75, the control section 10 correlates and acquires, for each of the plurality of lines 15, the information indicating the irradiation condition in the process S23 (here, the pulse energy D3) and the information indicating the formation state (here, the lower crack amount F4) with each other by the imaging in the process S24. Thereby, in the laser processing apparatus 1, it is possible to acquire the relationship between the irradiation condition and the formation state (it is possible to perform the parameter management) for the unknown object, for example. In particular, as shown in the graph J75, by displaying the graph in which the variable item (parameter) is taken as the horizontal axis AX and the formation state under the variable item is taken as the vertical axis AY, it is possible to perform the parameter management in a visualized manner. Therefore, the user can adjust the irradiation condition so that the modified region 12a, 12b, or the like becomes the required formation state. Figure 43

[0248] In the following process, the control section 10 displays the information J76 for guiding the selection of whether to continue the parameter management in the input accepting section 103. As shown in the graph J75, the information J76 has already been displayed in the process S25. Therefore, here, the input accepting section 103 accepts the selection (the process S26) as to whether to continue the parameter management. By the "continuing the parameter management", it means that the variable item or the judgment item is changed, and the reprocessing is performed. In the case where the result of the process S26 is the result indicating that the reprocessing is not required (the process S26: YES), the processing is ended. Figure 42

[0249] ​​On the other hand, if the result of the process S26 is a result indicating that reworking is necessary (process S26: No), as in the process S21, the control section 10 causes the input accepting section 103 to display the information J2 to guide the user to select the variable item, the information J3 to guide the user to select the judgment item, the information J4 to indicate that the selection of the processing condition is automatic, and the information J5 to indicate 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 judgment item selected in the process S21 can be set as the judgment item.

[0250] Next, the control section 10 performs processing according to the input accepted in the process S27, as in the process S23 (process S28), and performs imaging, as in the process S24 (process S29), thereby acquiring information indicating the formation state of the modified regions 12a, 12b, and the like.

[0251] Next, the control section 10 performs a fifth process (process S30) of judging 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. Here, in at least one of a case where the second end 14ae of the crack 14a is not confirmed in the image acquired in the imaging C5 and a case where the crack 14d is confirmed on the back surface 21b in the image acquired in the imaging C0, it can be judged that the cracks 14a, 14d have reached the outer surface.

[0252] In a case where the result of the judgment of the process S30 is a result indicating that the cracks 14a, 14d have reached the outer surface, that is, in a case other than the case where they have not reached the outer surface (process S30: No), the processing is shifted to the process S27. On the other hand, in a case where the result of the judgment of the process S30 is a result indicating that the cracks 14a, 14d have not reached the outer surface, that is, in a case where they have not reached the outer surface (process S30: Yes), as in the process S25, the control section 10 displays information indicating the processing result on the input accepting section 103 (process S31), and judges whether or not reworking is necessary (process S32). In a case where the result of the process S32 is a result indicating that reworking is not necessary, the processing is ended; in a case where the result of the process S32 is a result indicating that reworking is necessary, the processing is shifted to the process S27.

[0253] [Third Embodiment of Laser Processing Apparatus]

[0254] Next, another embodiment of the laser processing apparatus 1 will be described. Here, as with the second embodiment, the derivation of the irradiation conditions of the laser L is performed. However, here, the variable item is set to the LBA deviation amount D8 included in the condensing state D5 among the irradiation condition items. First, the LBA deviation amount 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. Also, the modulation pattern displayed on the reflection face 5a of the spatial light modulator 5 is transferred to the entrance pupil face 33a of the condensing lens 33.

[0255] The irradiation of the laser L is performed in a state in which the center of the modulation pattern has a deviation with respect to the center of the entrance pupil face 33a of the condensing lens 33, whereby the formation state of the modified regions 12a, 12b, etc. changes. In particular, by causing the center of at least the spherical aberration correction pattern among the modulation patterns to have a deviation with respect to the center of the entrance pupil face 33a of the condensing lens 33, the formation state can be properly controlled. The LBA deviation amount D8 is the amount of deviation of the center of this spherical aberration correction pattern with respect to the center of the entrance pupil face 33a of the condensing lens 33. Among the LBA deviation amount D8, the amount of deviation in the X direction is referred to as the X displacement amount, and the amount of deviation in the Y direction is referred to as the Y displacement amount. 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; the Y direction is the direction orthogonal to the travel direction of the condensing point of the laser, and is the direction perpendicular to the laser processing travel direction.

[0256] Figure 44 is a graph showing the relationship between the Y deviation amount and the formation state. In Figure 44 In (a) of FIG. 8, the modified regions 12 and the cracks 14 extending from the modified regions 12 in the case where the Y deviation amount is changed from -2.0 to +2.0 in units of 0.5 are shown. For each Y deviation amount, a pair of modified regions 12 (and the corresponding cracks 14) is shown, with the left side being for when processing in the forward direction (X positive direction), and the right side being for when processing in the return direction (X negative direction). Also, the Y deviation amount corresponds to the pixel of the spatial light modulator 5. Figure 44 (b) of FIG. 8 shows the cut surfaces after processing with each Y deviation amount. Also, in the example of Figure 44 In the example of FIG. 8, the X deviation amount is constant.

[0257] As described above, the laser processing apparatus 1 according to the present embodiment is configured to cause the center of the modulation pattern to have a deviation with respect to the center of the entrance pupil face 33a of the condensing lens 33, and to change the formation state of the modified regions 12a, 12b, etc. by the irradiation of the laser L in this state. Thus, the formation state of the modified regions 12a, 12b, etc. can be properly controlled. Figure 44As shown, when the modified region 12 and the crack 14 are formed in the semiconductor substrate 21 by irradiation with laser L, if the Y deviation amount is changed, the formation state of the modified region 12 and the crack 14 will also change. Therefore, by obtaining the formation state of the modified region 12 and the crack 14, the irradiation conditions of laser L that make the modified region 12 and the crack 14 form the desired formation state can be derived. In addition, the LBA deviation amount D8 is related to the presence or absence of the black line F9 between the upper crack tip position F1 and the modified region in the formation state. Hereinafter, the method for deriving the LBA deviation amount D8 in the irradiation conditions of laser L will be explained.

[0258] Figure 45 and Figure 46 This is a flowchart illustrating the main steps of the method for deriving the LBA deviation. The following method is a third embodiment of the laser processing method. (Example...) Figure 45 As shown, here, firstly, the control unit 10 receives input from the user (process S41). Process S41 will be described in more detail. In this process S41, firstly, information (not shown) guiding the user to select whether to perform an LBA deviation check is displayed on the input receiving unit 103. The LBA deviation check is a check used to derive the LBA deviation amount.

[0259] Next, in step S41, the input receiving unit 103 accepts the user's selection regarding whether to perform an LBA deviation check. Then, in step S41, if the input receiving unit 103 accepts the selection to perform an LBA deviation check, as follows... Figure 47 As shown, the control unit 10 displays information K1, which guides the selection of inspection conditions, on the input receiving unit 103. Information K1 includes multiple items. Among these items, LBA deviation check K2 is an item used to guide the user to select whether to perform an X deviation check (export), whether to perform a Y deviation check (export), or whether to perform a check (export) of both X and Y deviations.

[0260] LBA-X Deviation K3 represents the variable range of the X deviation (e.g., ±6), which can be selected by the user (or automatically). LBA-Y Deviation K4 represents the variable range of the Y deviation (e.g., ±2), which can be selected by the user (or automatically). Judgment Item K5 represents the formation state item used to derive the LBA deviation, which can be selected by the user (or automatically). Additionally, wafer thickness K6 can also be selected by the user (or automatically).

[0261] Next, in the process S41, the input accepting section 103 accepts at least the LBA deviation check K2 input. Also, in the case where the input accepting section 103 accepted the input of the LBA deviation check K2 (in the case of the LBA-X deviation K3, the LBA-Y deviation K4, the judgment item K5, and the wafer thickness K6, automatic selection is performed without input from the user), the control section 10 displays the setting screen including the selection result in the input accepting section 103 by controlling the input accepting section 103.

[0262] Figure 48 is a view of the input accepting section 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 deviation check K71, the judgment item K72, the X deviation variable range K73, the Y deviation variable range K74, and the wafer thickness K75 are items indicating the previous selection result, and are not items currently accepting selection from the user. Also, the LBA deviation check K71 indicates that the selection of the check (derivation) of both the X deviation amount and the Y deviation amount in the LBA deviation check K71 of Figure 47 is selected.

[0263] On the other hand, the focal point number K81, the scan 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 are examples of the control section 10 prompting, and are currently accepting selection (change) from the user. Also, 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 .

[0264] In the next process, the control section 10 performs a fourth process (process S42): that is, it judges whether or not the processing condition (irradiation condition) set in the process S41 is actually the condition (unreached condition) that does not allow the cracks 14a, 14d to reach the outer surfaces (the front surface 21a and the back surface 21b). Here, as with the above-described process S2, the control section 10 can judge whether or not the accepted input condition is the unreached condition. In the case where the result of the judgment of this process S42 indicates that the basic processing condition is not the unreached condition (process S42: No), the flow shifts to the process S41.

[0265] On the other hand, if the result of the judgment in process S42 indicates that the basic processing conditions have not been met (process S42: YES), processing is performed according to the selection content and processing conditions displayed on the setting screen K7 (process S43, first process). That is, here, the control unit 10 performs the first process: that is, it irradiates the semiconductor substrate 21 with laser L along multiple lines 15 respectively, so as not to reach the outer surface (surface 21a and back surface 21b) of the semiconductor substrate 21, thereby forming the modified regions 12a, 12b, etc. in the semiconductor substrate 21.

[0266] In particular, in process S43, laser L is applied to the semiconductor substrate 21 for each of the multiple lines 15 with different LBA deviations D8 (irradiation conditions, focusing state D5). As an example, the X deviation is kept constant, and the Y deviation is varied from -2 to +2 in units of 0.5, as shown in the Y deviation variable range K74, while laser L is applied. This results in modified regions 12a, 12b, etc., with different formation states being formed on each line 15.

[0267] Next, the control unit 10 performs a second process (step S44, second step): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed by light I1 that is transparent to the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or cracks 14a to 14b. In particular, in this step S44, information indicating the formation state is obtained for each of the multiple lines 15. Here, since the lower crack amount F4 is specified as a judgment item K5 (judgment item K72) in step S41, at least the imaging C5 and imaging C6 necessary to obtain the lower crack amount F4 must be performed (other imaging may also be performed).

[0268] Next, the control unit 10 displays information indicating the processing result on the input receiving unit 103 via the control input receiving unit 103 (process S45, third process). Figure 49 This is a diagram showing the status of the input receiving unit, which displays information indicating the processing result. For example... Figure 49 As shown, information K9 indicating the processing result is displayed in process S45. Information K9 indicating the processing result not only displays the LBA deviation check K71, judgment item K72, X deviation variable range K73, Y deviation variable range K74, and wafer thickness K75 mentioned above, but also judgment K91, X deviation judgment K92, Y deviation judgment K93, X deviation K95, and Y deviation K96.

[0269] The determination K91 indicates whether or not the determination of the LBA deviation amount required for the desired formation state (i.e., derivation of the LBA deviation amount) has been completed. Here, as an example of the LBA deviation amount required for the desired formation state, the lower crack amount F4 exemplifies the LBA deviation amount at which the peak is shown, however, it can not be the peak and can be set by the user. Here, in the determination K91, it is shown that the determination has been completed, i.e., it is shown that the lower crack amount F4 at which the peak is shown has been obtained.

[0270] Also, in the X deviation determination K92, the value of the X deviation amount at which the desired formation state (the lower crack amount F4 at which the peak is shown) can be obtained is indicated, and in the Y deviation determination K93, the value of the Y deviation amount at which the desired formation state (the lower crack amount F4 at which the peak is shown) can be obtained is indicated. That is, in the case where the peak of the formation state is obtained, the control section 10 displays the irradiation condition corresponding to the peak (here, the LBA deviation amount D8) in the input accepting section 103 by controlling the input accepting section 103. Also, in the above-described second embodiment, in the case where the peak is obtained, the control section 10 can also display the irradiation condition corresponding to the peak in the input accepting section 103. Also, even in the case where the peak of the formation state is obtained, the control section 10 can be caused to display the irradiation condition corresponding to the value shifted from the peak in the input accepting section 103. This is in order to make the irradiation condition at which the desired formation state can be obtained have a margin.

[0271] The X deviation K95 includes a graph K951 and an internal image lower crack front K952, and the Y deviation K96 includes a graph K961 and an internal image lower crack front K962. In the graph K951, the X deviation amount is correlated with the lower crack amount F4 and is displayed. Also, in the graph K961, the Y deviation amount is correlated with the lower crack amount F4 and is displayed. Also, in the information K9 indicating the processing result, for the time being, not only the information on the Y deviation is displayed, but also the information on the X deviation is displayed, however, at present, only the processing of making the Y deviation amount variable is performed, so the information on the X deviation is not displayed.

[0272] As shown in the graph K961, the lower crack amount F4 becomes the peak when the Y deviation amount is ±0. Therefore, in the Y deviation determination K93, ±0 is shown as the Y deviation amount at which the peak of the lower crack amount F4 is given. Also, in the determination K91, the determination (derivation) of the Y deviation amount at which the peak of the lower crack amount F4 is given is shown to be completed.

[0273] Thus, the relationship between the Y deviation amount and the under-crack amount F4 among the LBA deviation amounts D8 is shown in the graph K961. That is, in this process S45, the control section 10 performs a third process of associating (the graph K961 in which the association is established) and displaying, by controlling the input accepting section 103, the information indicating the irradiation conditions of the laser L in the process S43 (the first process) and the information indicating the formation state acquired in the process S44 (the second process) with each other on the input accepting section 103.

[0274] Also, the information indicating the formation state (the formation state item) displayed in this process S45 is the under-crack amount F4 of the judgment item K5 (the judgment item K72) set in the process S41. As described above, the judgment item K5 can be selected. Thus, in the process S41, the control section 10 performs a sixth process of causing the input accepting section 103 to display the information guiding the selection of the formation state item displayed on the input accepting section 103 in the process S45 among the plurality of formation state items, by controlling the input accepting section 103.

[0275] Also, the input accepting section 103 accepts the selection of the formation state item in the process S41. Next, in the process S45, the control section 10 associates and displays, by controlling the input accepting section 103, the information indicating the formation state item (the under-crack amount F4 in this case) accepted by the input accepting section 103 and the information indicating the irradiation conditions of the laser L (the LBA deviation amount D8 in this case) on the input accepting section 103.

[0276] In the next process, the control section 10 judges whether or not the judgment (derivation) of the LBA deviation amount D8 (the Y deviation amount in this case) is completed, that is, whether or not the LBA deviation amount at which the under-crack amount F4 shows a peak value is obtained (the process S46). In the case where the result of the judgment in the process S46 indicates the result that the judgment of the LBA deviation amount D8 is completed (the process S46: YES), the processing is performed in accordance with the selection contents and the processing conditions displayed on the setting screen K7 (the process S47, the first process). That is, in this case, the control section 10 performs a first process of irradiating the laser L to the semiconductor substrate 21 along the plurality of lines 15, respectively, in such a manner that the modified regions 12a, 12b, and the like are formed in the semiconductor substrate 21 without reaching the outer surfaces (the front surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0277] In particular, in this process S47, the laser L is irradiated to the semiconductor substrate 21 with the LBA deviation amounts D8 (the irradiation conditions, the condensing states) different from each other for the plurality of lines 15, respectively. In this case, the Y deviation amount is made constant, and the irradiation of the laser L is performed while the X deviation amount is changed from -6 to +6 as shown in the X deviation variable range K73. Thus, the modified regions 12a, 12b, and the like having different formation states are formed on the respective lines 15.

[0278] Next, the control section 10 executes a second process (step S48, second step) : that is, by controlling the imaging unit 4, the semiconductor substrate 21 is imaged by the light II that has the transmittance to the semiconductor substrate 21, thereby acquiring information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a to 14b. In particular, in this step S48, the information indicating the formation state is acquired for each of the plurality of lines 15. Here, since the lower crack amount F4 is designated as the judgment item K5 (judgment item K72) in the step S41, 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).

[0279] Next, the control section 10 executes a fifth process (step S49) : that is, based on the information indicating the formation state acquired in the step S48, it is judged whether or not the cracks 14a, 14d do not reach the outer surface. Here, in at least one of the case where the second end 14ae of the crack 14a is not confirmed in the image acquired in the imaging C5 and the case where the crack 14d is confirmed on the back surface 21b in the image acquired in the imaging C0, it can be judged that the cracks 14a, 14b reach the outer surface. In the case where the judgment result of the step S49 is the result indicating that the cracks 14a, 14d reach the outer surface, that is, not the case of not reaching (step S49: No (NO)), the processing proceeds to the step S41.

[0280] On the other hand, in the case where the judgment result of the step S49 is the result indicating that the cracks 14a, 14d do not reach the outer surface, that is, the case of not reaching (step S49: Yes (YES)), the control section 10 displays the information indicating the processing result on the input accepting section 103 by controlling the input accepting section 103 (step S50, third step). The information displayed here is the information K9 indicating the processing result shown in FIG. 9. At the time of the step S45, since only the processing of making the Y deviation amount variable is performed, the information on the X deviation is not displayed, however, here, the processing of making the X deviation amount variable is also finished, and therefore, the information on the X deviation (all the items of the display K91) is also displayed. As shown in the graph K951, in the processing in the forward direction, the lower crack amount F4 becomes the peak value when the X deviation amount is ±0. Also, in the processing in the return direction, the lower crack amount F4 becomes the maximum when the X deviation amount is +3. Therefore, in the X deviation judgment K92, ±0, +3 (the X deviation amount at which the maximum value of the lower crack amount F4 is given) are displayed as the X deviation amount at which the peak value of the lower crack amount F4 is given. Also, in the judgment K91, the judgment (derivation) of the X deviation amount at which the peak value of the lower crack amount F4 is given has been finished. Figure 49 Figure 49

[0281] ​​The relationship between the X deviation amount and the under-crack amount F4 among the LBA deviation amounts D8 is shown in the graph K951. That is, in this process S50, the control section 10 executes a third process of associating (the graph K951 in which the association is established) and displaying, by controlling the input accepting section 103, the information indicating the irradiation conditions of the laser L in the process S47 (the first process) and the information indicating the formation state acquired in the process S48 (the second process) with each other on the input accepting section 103.

[0282] Also, the information indicating the formation state (the formation state item) displayed in this process S50 is the under-crack amount F4 of the judgment item K5 (the judgment item K72) set in the process S41. As described above, the judgment item K5 can be selected. Therefore, in the process S41, the control section 10 executes a sixth process of causing the input accepting section 103 to display the information guiding the selection of the formation state item displayed on the input accepting section 103 in the process S50 among the plurality of formation state items, by controlling the input accepting section 103.

[0283] Also, the input accepting section 103 accepts the selection of the formation state item in the process S41. Next, in the process S50, the control section 10 associates and displays, by controlling the input accepting section 103, the information indicating the formation state item (the under-crack amount F4 in this case) accepted by the input accepting section 103 and the information indicating the irradiation conditions of the laser L (the LBA deviation amount D8 in this case) on the input accepting section 103.

[0284] In the next process, the control section 10 judges whether or not the judgment (derivation) of the LBA deviation amount D8 (the X deviation amount in this case) has been completed (the process S51). In the case where the result of the judgment in the process S51 is the result indicating that the judgment of the LBA deviation amount D8 has been completed (the process S51: YES), the process is ended. Also, the information K97 guiding the selection of whether or not to change the value of the LBA deviation amount D8 to the judged value (the value displayed on the X deviation judgment K92 and the Y deviation judgment K93) is displayed in the information K9 indicating the processing result. Also, at the time when the information K9 is displayed, the user can select whether or not to change the value of the LBA deviation amount D8 to the judged value.

[0285] In this case, in the case where the result of the judgment in the process S46 is the result indicating that the judgment of the Y deviation amount is not completed (the process S46: NO), and in the case where the result of the judgment in the process S51 is the result indicating that the judgment of the X deviation amount is not completed (the process S51: NO), it is judged that the required formation state (the peak in this case) cannot be obtained by the variable range of the LBA deviation amount D8 and the judgment item selected previously, and the flow shifts to the process S52 shown in FIG. 12. Figure 46 ​

[0286] That is, in the next process, the control section 10 expands the variable range of the LBA deviation amount D8 (process S52). In the case of shifting from the process S46 to the process S52, the variable range of the Y deviation amount among the LBA deviation amounts D8 is expanded from the Y deviation variable range K74 (±2); in the case of shifting from the process S51 to the process S52, the variable range of the X deviation amount among the LBA deviation amounts D8 is expanded from the X deviation variable range K73 (±6). Also, in the following process, although the judgment of the Y deviation amount is described, the case of the judgment of the X deviation amount is the same.

[0287] In the next process, the fourth processing is executed (process S53): that is, it is judged 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-reach condition. Here, as in the above process S2, the control section 10 can judge whether the condition corresponding to the expanded variable range is the non-reach condition. In the case where the result of the judgment in this process S53 indicates that the basic machining condition is not the non-reach condition (process S53: No (NO)), the shift is made to the process S52, and the expansion degree of the variable range is adjusted.

[0288] On the other hand, in the case where the result of the judgment in the process S53 indicates that the basic machining condition is the non-reach condition (process S53: Yes (YES)), machining is performed in the expanded variable range (process S54, first process). That is, here, the control section 10 executes the first processing: that is, the laser L is irradiated to the semiconductor substrate 21 along the plurality of lines 15, respectively, to form the modified regions 12a, 12b, etc. in the semiconductor substrate 21 in such a manner that the outer surfaces (the surface 21a and the back surface 21b) of the semiconductor substrate 21 are not reached.

[0289] In particular, in this process S54, the laser L is irradiated to the semiconductor substrate 21 with the Y deviation amount (irradiation condition, condensing state) different from each other for the plurality of lines 15, respectively. Here, the X deviation amount is made a constant value, and the irradiation of the laser L is performed while the Y deviation amount is changed to the expanded variable range. Thus, the modified regions 12a, 12b, etc. having different formation states are formed on the respective lines 15.

[0290] Next, the control section 10 executes the second processing (process S55, second process): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is imaged by the light II having the transmittance to the semiconductor substrate 21, and thus information indicating the formation states of the modified regions 12a, 12b and / or the cracks 14a to 14b is acquired. This process S55 is the same as the above process S3. Figure 45The process S44 shown is the same. Next, the control unit 10 displays information indicating the processing result on the input receiving unit 103 via the control input receiving unit 103 (process S56, third process). This process S56 is the same as... Figure 45 The process S45 shown is the same.

[0291] Next, the control unit 10 determines whether the determination (derivation) of the LBA deviation amount D8 (in this case, the Y deviation amount) has ended, that is, it determines whether the LBA deviation amount D8 that shows the peak value of the lower crack amount F4 was obtained in the expanded variable range (step S57). If the result of the determination in step S57 indicates that the determination of the LBA deviation amount D8 has ended (step S57: No), the process ends.

[0292] On the other hand, if the result of the judgment in process S57 indicates that the judgment of LBA deviation amount D8 has not been completed (process S57: YES), then the control unit 10 changes the judgment item (process S58). More specifically, in this case, the item used for judging LBA deviation amount D8 in the forming status item is set to be in Figure 47 The items other than the judgment item K5 (in this case, the lower crack amount F4) specified by the information K1 shown.

[0293] like Figure 50 As shown, in the case where the project is determined to be at the front end of the crack at position F3 ( Figure 50 (a) and the case where the front end of the upper crack is F1 ( Figure 50 (b) can all obtain a peak value corresponding to the change in Y deviation, and the Y deviation value assigned to this peak value is the same as that obtained by existing methods through cross-sectional observation. Figure 50 The Y deviation Oc in (c) is consistent. Furthermore, as... Figure 51 As shown, even when the project is determined to be a vertical crack with a deviation width of F6 at the front end, the peak value can be approximated by the change in the Y deviation. Furthermore, the Y deviation value assigned to this peak value is compared with that obtained by existing methods through cross-sectional observation. Figure 51 The Y deviation Oc in (c) is consistent.

[0294] And, as Figure 52 and Figure 53 As shown, even when the judgment item is the presence or absence of scratches in the modified area (F7), changes can be observed in the appearance of the scratches as the Y deviation changes. The clearest scratches are confirmed near the Y deviation ±0 (which is the same Y deviation as other judgment items and existing methods). Thus, in process S58, various judgment items can be used to replace the aforementioned lower crack amount F4.

[0295] Furthermore, the judgment of the X deviation is also the same. For example, as... Figure 54 As shown, even when the project is judged to have a lower cracking amount F4, a peak value can be obtained corresponding to the change in X deviation. Furthermore, the X deviation value assigned to this peak value is similar to that obtained by existing methods through cross-sectional observation. Figure 54 (b) has ±0 (outbound) and +2 (return) values ​​that are consistent. Furthermore, as... Figure 55 (Road) and Figure 56 As shown in the (reverse path) diagram, when the judgment item is the serpentine amount F8 at the lower crack front, it can also be observed that the serpentine amount F8 at the lower crack front changes in response to the change in the X deviation, and the serpentine amount F8 at the lower crack front becomes the minimum X deviation, consistent with the situation described above. Thus, the judgment of the X deviation can also be made using various judgment items.

[0296] Next, processing (step S59), imaging (step S60), and result display (step S62) are performed. Step S59 is the same as step S54 described above, step S60 is the same as step S55 described above, and step S62 is the same as step S56 described above. However, in step S60, the imaging C1 to C11 is used to capture images of the judgment items that have changed in step S58.

[0297] Furthermore, here, after step S60 and before step S62, the control unit 10 performs a fifth process (step S61): that is, based on the information indicating the formation state obtained in step S60, it determines whether the cracks 14a and 14d have not reached the outer surface. Here, if at least one of the following situations occurs: the second end 14ae of crack 14a is not confirmed in the image obtained by camera C5, and crack 14d is confirmed on the back side 21b in the image obtained by camera C0, it can be determined that cracks 14a and 14b have reached the outer surface. If the determination result of step S61 indicates that cracks 14a and 14d have reached the outer surface, that is, if they have not reached the outer surface (step S61: NO), the process proceeds to step S58; and if the determination result of step S61 indicates that cracks 14a and 14b have not reached the outer surface, that is, if they have not reached the outer surface (step S61: YES), the process proceeds to step S62 as described above.

[0298] Next, the control unit 10 determines whether the determination (derivation) of the LBA deviation amount D8 (in this case, the Y deviation amount) has been completed, that is, it determines whether the LBA deviation amount D8 has obtained the displayed peak value (the required state) for the changed determination item (process S63). If the result of the determination in process S63 indicates that the determination of the LBA deviation amount D8 has been completed (process S63: No), the process ends.

[0299] 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 deviation amount 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.

[0300] However, here, after the step S66 and before the step S68, the control section 10 performs a fifth processing (step S67): that is, it determines whether or not the cracks 14a, 14d have reached the outer surface based on the information indicating the formation state acquired in the step S65. Here, 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, 14b have reached 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 have reached the outer surface, that is, not the case where they have not reached (step S67: NO), the processing is shifted to the step S64; and in a case where the result of the determination in the step S67 is a result indicating that the cracks 14a, 14b have not reached the outer surface, that is, the case where they have not reached (step S67: YES), the processing is shifted to the step S68 as described above.

[0301] Subsequently, the control section 10 determines whether or not the determination of the LBA deviation amount D8 (here, the Y deviation amount) has been completed, that is, it determines whether or not the LBA deviation amount D8 of the changed irradiation conditions has obtained the display peak (the required state) (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 deviation amount D8 has been completed (step S69: NO), the processing is ended.

[0302] 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 deviation amount D8 is not completed (step S69: YES), the control section 10 displays information for notifying the user of an error in the input accepting section 103 by controlling the input accepting section 103 (step S70), and ends the processing. This is because, regardless of the enlargement of the variable range of the LBA deviation amount D8, the change of the determination item, or the change of the irradiation conditions, the required formation state cannot be obtained, so it is likely that there is an abnormality in the state of the apparatus.

[0303] [Effect Description]

[0304] As described above, in the laser processing apparatus 1 and the laser processing method of the above-described embodiment, after the modified regions 12a, 12b, etc. (cracks 14a to 14d extending from the modified regions 12a, 12b) are formed by irradiating the laser L to the semiconductor substrate 21, the semiconductor substrate 21 is photographed with light that penetrates the semiconductor substrate 21, and thus the formation state (processing result) of the modified regions 12a, 12b, etc. is acquired. Then, information of the irradiation conditions of the laser L and the formation state of the modified regions 12a, 12b, etc. are associated with each other and displayed. Therefore, when the correlation between the irradiation conditions of the laser L and the processing state is grasped, it is not necessary to cut the semiconductor substrate 21 or perform cross-sectional observation. Therefore, by the laser processing apparatus 1 and the laser processing method of the above-described embodiment, the correlation between the irradiation conditions of the laser L and the processing state can be easily grasped.

[0305] In particular, in the laser processing apparatus 1 and the laser processing method of the above-described embodiment, the correlation between the formation state of the modified regions 12a, 12b and the irradiation conditions of the laser L can be grasped in a state where the modified regions 12a, 12b and the cracks 14a to 14d are not exposed to 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, the modified regions 12a, 12b are less likely to be affected 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.

[0306] Further, the laser processing apparatus 1 of the above-described embodiment is provided with the input accepting section 103 to display information and to accept input. Therefore, it is possible to accept input of information from the user.

[0307] Further, in the laser processing apparatus 1 of the above-described embodiment, the control section 10 performs a fourth process of causing the input accepting section 103 to display information that guides selection of the formation state item included in the formation state among a plurality of formation state items by controlling the input accepting section 103. Then, the input accepting section 103 accepts input of selection of the formation state item. Subsequently, in the third process, the control section 10 causes the input accepting section 103 to display information indicating the formation state item accepted by the input accepting section 103 and information indicating the irradiation conditions in association with each other by controlling the input accepting section 103.

[0308] Here, the semiconductor substrate 21 includes a back surface 21b that is an incident surface of the laser L, and a surface 21a on the opposite side of the back surface 21b. The cracks include a crack 14d extending from the modified region 12b toward the back surface 21b, and a crack 14a extending from the modified region 12a toward the surface 21a. Also, the formation state includes, as formation state items, a length of the crack 14b in the Z direction (upper crack amount F2), a length of the crack 14a in the Z direction (lower crack amount F4), a total amount of lengths of the cracks 14a to 14d in the Z direction (total crack amount F5), a position of a first end 14de of a front end of the crack 14d on the back surface 21b side in the Z direction (upper crack front end position F1), a position of a second end 14ae of a front end of the crack 14a on the surface 21a side in the Z direction (lower crack front end position F3), a deviation width of the first end 14de and the second end 14ae when viewed in the Z direction (upper and lower crack front end position deviation width F6), presence or absence of a mark of the modified region 12a, 12b (presence or absence of a modified region mark F7), a meandering amount of the second end 14ae when viewed in the Z direction (lower crack front end meandering amount F8), and presence or absence of a front end of a crack in a region between the modified regions 12a, 12b arranged in the Z direction (presence or absence of a black line between modified regions F9).

[0309] Therefore, it is possible to easily grasp the correlation between the items selected by the user among the formation states of the modified regions 12a, 12b, etc. and the irradiation conditions.

[0310] Also, in the laser processing apparatus 1 of the above embodiment, the control section 10 performs a seventh process of causing the input accepting section 103 to display information that guides selection of the irradiation condition item displayed on the input accepting section 103 in the third process among a plurality of irradiation condition items included in the irradiation conditions, by controlling the input accepting section 103. Also, the input accepting section 103 accepts input of selection of the irradiation condition item. Subsequently, in the third process, the control section 10 causes the input accepting section 103 to display information representing the irradiation condition item and information representing the formation state, which are accepted by the input accepting section 103, in association with each other, by controlling the input accepting section 103.

[0311] At this time, the irradiation conditions include, as the irradiation condition items, a pulse width of the laser L (pulse width D2), a pulse energy of the laser L (pulse energy D3), a pulse pitch of the laser L (pulse pitch D4), and a condensing state of the laser L (condensing state D5). Also, in the third process, the control section 10 causes the input accepting section 103 to display information representing the irradiation condition item and information representing the formation state, which are accepted by the input accepting section 103, in association with each other, by controlling the input accepting section 103.

[0312] Further, the laser processing apparatus 1 includes a spatial light modulator 5 that displays a spherical aberration correction pattern for correcting spherical aberration of the laser light L, and a condensing lens 33 that condenses the laser light L modulated by the spherical aberration correction pattern in the spatial light modulator 5 on the semiconductor substrate 21. The condensing state D5 includes an amount of deviation (LBA deviation amount D8) of a center of the spherical aberration correction pattern with respect to a center of an entrance pupil plane 33a of the condensing lens 33.

[0313] Further, in the case where, in the first process, a plurality of modified regions 12a, 12b are formed at positions different from each other in the Z direction intersecting the laser light L incident plane (back surface 21b) of the semiconductor substrate 21, the interval of the modified regions 12a, 12b in the Z direction (modified region interval D1) is included as the irradiation condition item.

[0314] Therefore, it is possible to easily grasp the correlation between the item selected by the user among the irradiation conditions of the laser light L and the formation state.

[0315] Further, in the laser processing apparatus 1 of the above-described embodiment, in the third process, the control section 10 displays, on the input accepting section 103, a chart in which information indicating the irradiation conditions of the laser light L and information indicating the formation state of the modified regions 12a, 12b and the like are correlated with each other, by controlling the input accepting section 103. Therefore, it is possible to visually grasp the correlation between the irradiation conditions of the laser light L and the formation state of the modified regions 12a, 12b and the like.

[0316] [Explanation of Modified Examples]

[0317] One aspect of the present application is explained in the above-described embodiment. Therefore, 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 into individual functional elements 22a along a plurality of lines 15 is exemplified (an example of cutting). However, the laser processing apparatus 1 can also be applied to processing of cutting an object along an imaginary plane with respect to the laser light incident plane (inside the object) of the object (processing of peeling in the thickness direction), or to trimming processing of cutting a region in a ring shape including the outer edge of the object from the object, and the like.

[0319] Further, in the above-described embodiment, as the object of the laser processing apparatus 1, the wafer 20 including the silicon substrate, that is, the semiconductor substrate 21 is exemplified. However, as the object of the laser processing apparatus 1, it is not limited to an object including silicon.

[0320] Also, in each of the above-described embodiments, a part of the irradiation condition item, the formation state item, and the combination thereof is exemplified as the irradiation condition item, the formation state item, and the combination thereof, however, it 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 judgment of the pass or fail of the LBA deviation amount D8 exemplified in the third embodiment can also be performed.

[0321] Also, in the above-described examples, with respect to "a case where the judgment of whether the irradiation condition is the non-arrival condition is performed (the fourth process) before the process of performing the processing is performed, the setting of the irradiation condition for the processing is accepted", and "a case where the process of performing the processing is performed, and the judgment of whether the cracks 14a, 14d do not arrive at the outer surface is performed (the fifth process) after the process of acquiring the information indicating the formation state is performed", an example of the timing of the execution is indicated, however, the timing of the execution of these processes is not limited to the above-described example, and can be arbitrary.

[0322] [Industrial applicability]

[0323] A laser processing device and a laser processing method in which the correlation between the irradiation condition of the laser and the processing result can be easily grasped can be provided.

[0324] [Explanation of symbols]

[0325] 1: Laser processing device

[0326] 3: Laser irradiation unit (irradiation section)

[0327] 4: Imaging unit (imaging section)

[0328] 5: Spatial light modulator

[0329] 10: Control section

[0330] 11: Object

[0331] 21: Semiconductor substrate

[0332] 33: Condenser lens

[0333] 33a: Incident pupil plane

[0334] 103: Input accepting section (input section, display section)

Claims

1. A laser processing apparatus, wherein, have: Irradiation section, used to irradiate an object with laser light; A camera unit for capturing an image of the object using light that is transparent to the object; Display unit, used to display information; and The control unit controls at least the illumination unit, the camera unit, and the display unit. The control unit performs the following processing: The first process involves controlling the irradiation unit to irradiate the object with the laser in a manner that 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, thereby forming modified particles and cracks extending from the modified particles in the object. The second process, after the first process, involves controlling the camera unit to capture an image of the object to obtain information representing the formation state of the modified particles and / or the cracks; as well as In the third process, following the second process, the display unit is controlled to establish a correlation between information indicating the laser irradiation conditions in the first process and information indicating the formation state obtained in the second process, and this correlation is then displayed on the display unit. In the second process, at least the following video recordings are performed: The object is photographed by focusing the light with transmissivity on the front end of the virtual image of the lower crack, so that the focus of the light with transmissivity is focused from the second surface side to the front end of the second surface side of the lower crack. as well as, By focusing the translucent light on the front end of the virtual image of the modified particle on the second surface side, the object is photographed. in, The lower crack is a crack that extends from the modified particles 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: The fourth step, prior to the first step, involves determining whether the irradiation condition is a "not reached" condition, where the crack has not reached the outer surface. If the result of the fourth process is that the irradiation condition is not met, the first process is executed.

3. The laser processing apparatus as described in claim 1 or 2, wherein, The control unit performs: The fifth process, occurring after the second process and before the third process, involves determining whether the cracks have not reached the outer surface based on the information indicating the formation state obtained in the second process. If the result of the fifth process is that the modified particles and the cracks have not reached the outer surface, then the third process is executed.

4. The laser processing apparatus as described in claim 1, wherein, It has an input section, which is used to accept input.

5. The laser processing apparatus as described in claim 4, wherein, The control unit performs a sixth process: by controlling the display unit, the display unit displays information used to guide the selection of the formation state item displayed on the display unit in the third process from among the items included in the formation state, i.e., multiple formation state items. The input section accepts input from the selection of the forming status item. In the third process, the control unit controls the display unit to associate information representing the formation state item received by the input unit in the formation state with information representing the irradiation conditions and displays it on the display unit.

6. The laser processing apparatus as described in claim 5, wherein, The object comprises: a first surface that serves as the incident surface of the laser, and a second surface opposite to the first surface. The cracks include: 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 is the front end of the first surface side of the first crack in the first direction; The position of the second end is 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 snake-like movement at the second end when viewed from the first direction; as well as In the first process, when multiple modified particles are formed at different positions in a direction intersecting the first surface, the region between the modified particles arranged in a direction intersecting the first surface has or does not have the tip of the crack.

7. The laser processing apparatus according to any one of claims 4 to 6, wherein, The control unit performs a seventh process, which involves controlling the display unit to display information for guiding the selection of the irradiation condition item displayed on the display unit in the third process from among a plurality of irradiation condition items included in the irradiation conditions. The input section accepts input for selecting the irradiation condition item. In the third process, the control unit controls the display unit to associate the information representing the irradiation condition items received by the input unit in the irradiation conditions with the information representing the formation state and displays it on the display unit.

8. The laser processing apparatus as described in claim 7, wherein, The irradiation conditions include at least one of the following items as irradiation condition items: The pulse width of the laser; The pulse energy of the laser; The pulse spacing of the laser; The focusing state of the laser; as well as In the first process, if multiple modified particles are formed at different positions in the direction intersecting the incident plane of the laser on the object, the spacing between the modified particles in the direction intersecting the incident plane is... In the third process, the control unit controls the display unit to associate at least one piece of information representing the irradiation condition with information representing the formation state and displays it on the display unit.

9. The laser processing apparatus as described in claim 8, wherein, have: A spatial light modulator that displays a spherical aberration correction pattern for correcting spherical aberration of the laser; and A condenser lens, used to focus the laser light, modulated in the spatial light modulator by the spherical aberration correction pattern, onto the object. The focusing state includes the deviation of the center of the spherical aberration correction pattern from the center of the pupil plane of the focusing lens.

10. The laser processing apparatus according to any one of claims 1, 2, 4 to 6, wherein, In the third process, the control unit controls the display unit to display a graph on the display unit that correlates information representing the irradiation conditions with information representing the formation state.

11. A laser processing method, wherein, The following processes are required: In the first step, a laser is irradiated onto an object, and modified particles and cracks extending from the modified particles are formed in 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. The second step, after the first step, involves photographing the object using light that is transparent to it, to obtain information representing the formation state of the modified particles and / or the cracks. as well as The third step, following the second step, involves establishing and displaying a correlation between the information representing the laser irradiation conditions in the first step and the information representing the formation state obtained in the second step. In the second process, at least the following video recordings shall be performed: The object is photographed by focusing the light with transmissivity on the front end of the virtual image of the lower crack, so that the focus of the light with transmissivity is focused from the second surface side to the front end of the second surface side of the lower crack. as well as, By focusing the translucent light on the front end of the virtual image of the modified particle on the second surface side, the object is photographed. in, The lower crack is a crack that extends from the modified particles 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