Laser processing device and laser processing method

Abstract

A laser processing device comprises: an irradiation unit for irradiating a laser onto an object; an imaging unit for imaging the object; and a control unit for controlling at least the irradiation unit and the imaging unit, wherein the control unit performs the following processing: a first processing of controlling the irradiation unit to irradiate the laser onto the object so as to form modified points and cracks extending from the modified points in the object in a manner that does not reach the outer surface of the object; a second processing of controlling the imaging unit to image the object with light that is transparent to the object after the first processing, thereby obtaining information indicating the formation status of the modified points and / or the cracks for each of the multiple lines; and a third processing of determining whether the irradiation conditions of the laser used in the first processing are qualified or not based on the information indicating the formation status obtained by the second processing after the second processing.

Description

Technical Field

[0001] The invention relates to a laser processing device and a laser processing method. Background Art

[0002] Patent document 1 describes a laser cutting device. The laser cutting device includes: a stage for moving a wafer, a laser head for irradiating the wafer with laser light, and a control unit for controlling each part. The laser head includes: a laser source for emitting a processing laser for forming a modified region inside the wafer; a beam splitter and a focusing lens sequentially arranged on the optical path of the processing laser light; and an autofocus device.

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent No. 5743123 Summary of the invention

[0006] [Technical problem to be solved by the invention]

[0007] However, in order to adjust the laser irradiation conditions for the above-mentioned wafer or other object to the conditions that can obtain the desired processing results, it is assumed that the following steps will be taken. That is, first, laser processing is performed under predetermined irradiation conditions. Then, the object is cut in a manner that the cross section formed with the modified area is exposed. Then, by observing the cut surface, the actual processing result for the irradiation conditions is grasped. In addition, it is judged whether the processing result is the desired result or not, and if the desired result is not achieved, the irradiation conditions are corrected.

[0008] On the other hand, in such a method, it is time-consuming and requires extensive knowledge of cross-sectional observation to adjust the irradiation conditions. Therefore, in the above technical field, it is desired to simplify the judgment of whether the irradiation conditions are qualified or not based on the processing results.

[0009] An object of the present invention is to provide a laser processing device and a laser processing method that can simplify the pass / fail judgment of laser irradiation conditions based on processing results.

[0010] [Technical means to solve technical problems]

[0011] The laser processing device of the present invention comprises: an irradiation unit, which is used to irradiate a laser on an object; an imaging unit, which is used to photograph the object; and a control unit, which controls at least the irradiation unit and the imaging unit, wherein the control unit performs the following processing: a first processing, by controlling the irradiation unit, irradiating the object with laser light to form modified points and cracks extending from the modified points in the object in a manner that does not reach the outer surface of the object; a second processing, after the first processing, by controlling the imaging unit, photographing the object with light that is transparent to the object, thereby obtaining information indicating the formation status of the modified points and / or cracks; and a third processing, after the second processing, judging whether the irradiation conditions in the first processing are qualified based on the information indicating the formation status obtained by the second processing.

[0012] The laser processing method of the present invention comprises the following steps: a first step of irradiating an object with a laser to form modified points and cracks extending from the modified points in the object in a manner that does not reach the outer surface of the object; a second step of, after the first step, photographing the object by light that is transparent to the object, thereby obtaining information indicating the formation status of the modified points and / or cracks; and a third step of, after the second step, judging whether the irradiation conditions in the first step are qualified based on the information indicating the formation status obtained in the second step.

[0013] In these devices and methods, after the object is irradiated with laser light to form modified points (modified points and cracks extending from the modified points), the object is photographed by light penetrating the object, and the formation state of the modified points (processing results) is obtained. And, thereafter, the pass or fail of the laser irradiation conditions is judged based on the formation state of the modified points. Therefore, when judging the pass or fail of the laser irradiation conditions based on the formation state of the modified points, there is no need to cut the object or observe the cross section. Therefore, through this device and method, it is possible to simplify the judgment of the pass or fail of the laser irradiation conditions based on the processing results.

[0014] The laser processing device of the present invention may also be configured such that: the control unit performs a fourth process, that is, before the first process, determines whether the irradiation condition is a condition in which the cracks do not reach the outer surface, that is, a non-reaching condition; and when the result of the fourth process is that the irradiation condition is the non-reaching condition, the first process is performed. In this case, the processing can be performed in a manner that ensures that the cracks do not reach the outer surface of the object.

[0015] In the laser processing device of the present invention, the control unit may perform a fifth process, that is, after the second process and before the third process, determine whether the cracks have reached the outer surface based on the information indicating the formation state obtained by the second process; and if the result of the fifth process is that the cracks have not reached the outer surface, the third process is performed. In this case, it is possible to determine whether the laser irradiation conditions are qualified or not in a state where the cracks have not reached the outer surface of the object.

[0016] The laser processing device of the present invention may include: a display unit for displaying information; and an input unit for receiving input. In this case, information can be presented to the user and information input from the user can be received.

[0017] In the laser processing device of the present invention, the control unit may perform the sixth process, that is, after the third process, the control unit controls the display unit to display information indicating the result of the pass / fail judgment on the display unit. In this case, the result of the pass / fail judgment can be presented to the user.

[0018] In the laser processing device of the present invention, the control unit may perform the seventh process, that is, before the third process, the control unit controls the display unit to display information for guiding the input of the target value of the forming state on the display unit; the input unit receives the input of the target value; in the third process, the control unit compares the forming state under the irradiation conditions in the first process with the target value based on the information indicating the forming state obtained by the second process, thereby making a pass / fail judgment. In this case, it is possible to make a pass / fail judgment on the processing state (target value of the forming state) requested by the user.

[0019] In the laser processing device of the present invention, the control unit may calibrate at least one of the plurality of irradiation condition items included in the irradiation condition as a correction item based on the result of the pass / fail judgment of the third process, and re-judge the process after re-executing the first process. In this case, the irradiation condition of the laser can be automatically calibrated and re-judged based on the result of the pass / fail judgment.

[0020] In the laser processing device of the present invention, the control unit may perform the eighth process, that is, according to the result of the pass / fail judgment of the third process, at least one of the multiple irradiation condition items included in the irradiation condition is corrected as a correction item by controlling the display unit, and information guiding the selection of whether to perform a re-judgment of the process after the first process is displayed on the display unit; the input unit receives an input of a selection of whether to perform a re-judgment, and when the input unit receives a selection of re-judgment, the control unit performs a re-judgment. In this case, when the result of the pass / fail judgment is unqualified, it is possible to select whether to perform correction and re-judgment of the laser irradiation condition.

[0021] In the laser processing device of the present invention, the control unit may perform the ninth process, that is, by controlling the display unit, information for guiding the selection of the correction item is displayed on the display unit; the input unit receives the input of the selection of the correction item, and the control unit corrects the correction item received by the input unit and re-judges. In this case, the irradiation condition includes at least one of the following items as the irradiation condition item: the pulse waveform of the laser; the pulse energy of the laser; the pulse interval of the laser; the focusing state of the laser; and, in the first process, when a plurality of modified points are formed at different positions in the direction intersecting the incident surface of the laser light of the object, the interval of the modified points in the direction intersecting the incident surface.

[0022] Furthermore, the laser processing device of the present invention may also include: a spatial light modulator, which displays a spherical aberration correction pattern for correcting the spherical aberration of the laser; and a focusing lens, which is used to focus the laser modulated by the spherical aberration correction pattern in the spatial light modulator onto an object, wherein the focusing state includes the deviation of the center of the spherical aberration correction pattern relative to the center of the pupil plane of the focusing lens.

[0023] In this case, the item selected by the user among the laser irradiation conditions can be corrected and re-judged.

[0024] In the laser processing device of the present invention, it can also be that: the control unit executes the tenth processing, that is, before the third processing, by controlling the display unit, the display unit displays information for guiding the selection of items for pass / fail judgment (that is, judgment items) from among multiple forming state items included in the forming state; the input unit accepts input of the selection of the judgment item, and in the third processing, the control unit performs the pass / fail judgment based on the information representing the judgment items in the forming state obtained by the second processing.

[0025] At this time, the object includes: a first surface, which is an incident surface of the laser, and a second surface on the opposite side of the first surface; the cracks include: a first crack extending from a modified point to the first surface side, and a second crack extending from the modified point to the second surface side; and the formation state includes at least one of the following items as a formation state item: the length of the first crack in a 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, which is the front end of the first surface side of the first crack in the first direction; the position of the second end, which 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 observed from the first direction; the presence or absence of traces of the modified point; the amount of meandering of the second end when observed from the first direction; and, in the first process, when a plurality of modified points are formed at different positions in the direction intersecting the first surface, whether there is a front end of the crack in the area between the modified points arranged in the direction intersecting the first surface.

[0026] In this case, it is possible to judge whether the item selected by the user is acceptable or not in the formation state of the modified points, etc.

[0027] [Effects of the invention]

[0028] According to the present invention, it is possible to provide a laser processing apparatus and a laser processing method that can simplify the pass / fail determination of laser irradiation conditions based on processing results. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] [ Figure 1 ] is a schematic diagram showing the structure of a laser processing device according to one embodiment.

[0030] [ Figure 2 ] is a top view of a wafer according to one embodiment.

[0031] [ Figure 3 ]yes Figure 2 A cross-sectional view of a portion of a wafer is shown.

[0032] [ Figure 4 ] is to indicate Figure 1 A schematic diagram of the structure of the laser irradiation unit is shown.

[0033] [ Figure 5 ] is to indicate Figure 4 Diagram of the relay lens unit shown.

[0034] [ Figure 6 ]yes Figure 4 A partial cross-sectional view of a spatial light modulator is shown.

[0035] [ Figure 7 ] is to indicate Figure 1A schematic diagram of the structure of the camera unit is shown.

[0036] [ Figure 8 ] is to indicate Figure 1 A schematic diagram of the structure of the camera unit is shown.

[0037] [ Fig. 9 ] is used to illustrate Figure 7 A cross-sectional view of a wafer illustrating the imaging principle of an imaging unit and images of various parts obtained by the imaging unit.

[0038] [ Fig.10 ] is used to illustrate Figure 7 A cross-sectional view of a wafer illustrating the imaging principle of an imaging unit and images of various parts obtained by the imaging unit.

[0039] [ Fig.11 ] is a SEM image of the modified region and cracks formed inside the semiconductor substrate.

[0040] [ Fig.12 ] is a SEM image of the modified region and cracks formed inside the semiconductor substrate.

[0041] [ Fig.13 ] is used to illustrate Figure 7 The optical path diagram of the imaging principle of the imaging unit shown, and a schematic diagram of an image representing the focus of the imaging unit.

[0042] [ Fig.14 ] is used to illustrate Figure 7 The optical path diagram of the imaging principle of the imaging unit shown, and a schematic diagram of an image representing the focus of the imaging unit.

[0043] [ Fig.15 ] is used to illustrate Figure 7 The inspection principle of the imaging unit shown is a cross-sectional view of a wafer, an image of a cut surface of the wafer, and images of various locations obtained by the imaging unit.

[0044] [ Fig.16 ] is used to illustrate Figure 7 The inspection principle of the imaging unit shown is a cross-sectional view of a wafer, an image of a cut surface of the wafer, and images of various locations obtained by the imaging unit.

[0045] [ Fig.17 ] is a cross-sectional view of an object used to illustrate a method of obtaining a formed state.

[0046] [ Fig.18 ] is a graph showing the change in the amount of cracking when the modified region interval is changed at three points.

[0047] [ Fig.19] is a graph showing the change in the amount of cracking when the modified region interval is changed at three points.

[0048] [ Fig. 20 ] is a graph showing the change in the amount of cracking when the pulse width of the laser is changed at three points.

[0049] [ Fig.21 ] is a graph showing the change in the amount of cracking when the pulse width of the laser is changed at three points.

[0050] [ Fig. 22 ] is a graph showing the change in the amount of cracking when the pulse energy of the laser is changed at three points.

[0051] [ Fig.23 ] is a graph showing the change in the amount of cracking when the laser pulse energy is changed at three points.

[0052] [ Fig.24 ] is a graph showing the change in the amount of cracking when the pulse interval of the laser is changed at four points.

[0053] [ Fig.25 ] is a graph showing the change in the amount of cracking when the pulse interval of the laser is changed at four points.

[0054] [ Fig.26 ] is a graph showing the change in the amount of cracking when the focusing state of the laser (spherical aberration correction level) is changed at three points.

[0055] [ Fig. 27 ] is a graph showing the change in the amount of cracking when the focusing state of the laser (spherical aberration correction level) is changed at three points.

[0056] [ Fig.28 ] is a graph showing the change in the amount of cracking when the focusing state of the laser (astigmatism correction level) is changed at three points.

[0057] [ Fig.29 ] is a graph showing the change in the amount of cracking when the focusing state of the laser (astigmatism correction level) is changed at three points.

[0058] [ Fig.30 ] is a graph showing the change in the presence or absence of black lines when the pulse interval of the laser is changed at four points.

[0059] [ Fig.31 ] is a graph showing the change in the presence or absence of black lines when the pulse interval of the laser is changed at four points.

[0060] [ Fig.32 ] is a flow chart showing the main steps of the pass / fail judgment method.

[0061] [ Fig.33 ] is to indicate Figure 1 A diagram of an example of an input receiving unit shown.

[0062] [ Fig.34 ] is a diagram of an input receiving unit showing a state in which an example of basic processing conditions is displayed.

[0063] [ Fig.35 ] is a diagram of an input receiving unit showing a state in which information guiding selection of a correction item is displayed.

[0064] [ Fig.36 ] is a diagram of an input receiving unit showing the state of a setting screen displaying reprocessing conditions.

[0065] [ Fig.37 ] is a diagram of an input receiving unit showing a state in which information indicating a judgment result (qualified) is displayed.

[0066] [ Fig.38 ] is a diagram of an input receiving unit showing a state in which information indicating a judgment result (failed) is displayed.

[0067] [ Fig.39 ] is a flow chart showing the main steps of the method for deriving irradiation conditions.

[0068] [ Fig.40 ] is to indicate Figure 1 A diagram of an example of an input receiving unit shown.

[0069] [ Fig.41 ] is a diagram of an input receiving unit showing a state in which an example of selected processing conditions is displayed.

[0070] [ Fig.42 ] is a diagram of an input receiving unit showing a state in which information indicating a processing result is displayed.

[0071] [ Fig.43 ] is a graph showing the relationship between irradiation conditions and formation state.

[0072] [ Fig.44 ] is a diagram showing the relationship between the Y deviation amount and the forming state.

[0073] [ Fig.45 ] is a flowchart showing the main steps of the method for deriving the LBA deviation.

[0074] [ Fig.46 ] is a flowchart showing the main steps of the method for deriving the LBA deviation.

[0075] [ Fig.47] is a diagram of an input receiving unit showing a state in which information guiding selection of inspection conditions is displayed.

[0076] [ Fig.48 ] is a diagram of the input receiving unit showing a state in which a setting screen is displayed.

[0077] [ Fig.49 ] is a diagram of an input receiving unit showing a state in which information indicating a processing result is displayed.

[0078] [ Fig.50 ] is a diagram showing the relationship between the Y deviation amount and the judgment item.

[0079] [ Fig.51 ] is a diagram showing the relationship between the Y deviation amount and the judgment item.

[0080] [ Fig.52 ] is a diagram showing the relationship between the Y deviation amount and the judgment item.

[0081] [ Fig.53 ] is a diagram showing the relationship between the Y deviation amount and the judgment item.

[0082] [ Fig.54 ] is a diagram showing the relationship between the X deviation amount and the judgment item.

[0083] [ Fig.55 ] is a diagram showing the relationship between the X deviation amount and the judgment item.

[0084] [ Fig.56 ] is a diagram showing the relationship between the X deviation amount and the judgment item. DETAILED DESCRIPTION

[0085] Hereinafter, one embodiment will be described in detail with reference to the accompanying drawings. In addition, in each figure, the same or corresponding parts are sometimes given the same symbols and repeated descriptions are omitted. Also, in each figure, a rectangular coordinate system defined by an X-axis, a Y-axis, and a Z-axis is sometimes indicated.

[0086] Figure 1 Schematic diagram showing the structure of a laser processing device according to one embodiment. Figure 1 As shown, the laser processing apparatus 1 includes a stage 2, a laser irradiation unit 3, a plurality of imaging units 4, 7, 8, a drive unit 9, and a control unit 10. The laser processing apparatus 1 irradiates a target object 11 with laser light L to form a modified region 12 in the target object 11.

[0087] The stage 2 supports the object 11 by, for example, sucking a thin film attached to the object 11. The stage 2 can move in the X direction and the Y direction, respectively, and can rotate with an axis parallel to the Z direction as a center line. In addition, the X direction and the Y direction are the first horizontal direction and the second horizontal direction that intersect (orthogonal) each other, and the Z direction is a vertical direction.

[0088] The laser irradiation unit (irradiation section) 3 focuses the laser light L having transmittance to the object 11 and irradiates the object 11. When the laser light L is focused inside the object 11 supported by the stage 2, the laser light L is particularly absorbed in the portion corresponding to the focal point C of the laser light L, thereby forming a modified region 12 inside the object 11.

[0089] The modified region 12 is a region whose density, refractive index, mechanical strength or other physical properties are different from those of the surrounding non-modified region. Examples of the modified region 12 include a melt-processed region, a crack region, an insulation breakdown region, and a refractive index change region. The modified region 12 may be formed by extending cracks from the modified region 12 toward the incident side and the opposite side of the laser L. Such modified regions 12 and cracks are used, for example, to cut the object 11.

[0090] As an example, the stage 2 is moved along the X direction, so that the focal point C moves relatively along the X direction with respect to the object 11, and a plurality of modified points 12s are formed in a row along the X direction. One modified point 12s is formed by irradiation with one pulse of laser L. A row of modified regions 12 is a collection of a plurality of modified points 12s arranged in a row. Therefore, like the modified region 12, the modified point 12s is a point whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding non-modified parts. For adjacent modified points 12s, depending on the relative moving speed of the focal point C with respect to the object 11 and the repetition frequency of the laser L, there are cases where they are connected to each other or separated from each other.

[0091] More specifically, the imaging unit (imaging section) 4 captures 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 capture the object 11 supported by the stage 2 using light that penetrates the object 11 under the control of the control section 10. The images captured by the imaging units 7 and 8 are used, for example, for aligning the irradiation position of the laser light L.

[0092] The driving unit 9 supports the laser irradiation unit 3 and the plurality of imaging units 4, 7, and 8. The driving unit 9 moves the laser irradiation unit 3 and the plurality of imaging units 4, 7, and 8 in the Z direction.

[0093] The control unit 10 controls the actions of the stage 2, the laser irradiation unit 3, the multiple camera units 4, 7, 8 and the driving unit 9. The control unit 10 has a processing unit 101, a storage unit 102, and an input receiving unit (display unit, input unit) 103. The processing unit 101 is configured as a computer device including a processor, a memory, a storage, and a communication device. In the processing unit 101, the processor executes the software (program) read by the memory, reads or writes data in the memory and the storage, and controls the communication performed by the communication device. The storage unit 102 is, for example, a hard disk, which stores various data. The input receiving unit 103 is an interface unit that displays various information and receives input of various information from the user. In the present embodiment, the input receiving unit 103 constitutes a GUI (Graphical User Interface).

[0094] [Structure of the object]

[0095] Figure 2 This is a top view of a wafer according to one embodiment. Figure 3 yes Figure 2 An example of the object 11 of this embodiment is Figure 2 , Figure 3 The wafer 20 shown in FIG. 2 includes a semiconductor substrate 21 and a functional element layer 22. The semiconductor substrate 21 has a surface 21a and a back surface 21b. As an example, the back surface 21b is a first surface that becomes an incident surface of a laser L, etc., and the surface 21a is a second surface on the opposite side of the first surface. The semiconductor substrate 21 is, for example, a silicon substrate. The functional element layer 22 is formed on the surface 21a of the semiconductor substrate 21. The functional element layer 22 includes a plurality of functional elements 22a arranged in a two-dimensional manner along the surface 21a.

[0096] The functional element 22a is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, etc. The functional element 22a may also be formed in a three-dimensional manner by stacking a plurality of layers. In addition, a groove 21c indicating a crystal orientation is provided on the semiconductor substrate 21, but an orientation plane may be provided instead of the groove 21c. In addition, the object 11 may also be a bare wafer.

[0097] The wafer 20 is cut into individual functional elements 22a along a plurality of lines 15. When observed from the thickness direction of the wafer 20, the plurality of lines 15 pass through each of the plurality of functional elements 22a. More specifically, when observed from the thickness direction of the wafer 20, the plurality of lines 15 pass through the center (center in the width direction) of the grid line area 23. The grid line area 23 extends in the functional element layer 22 in a manner passing between adjacent functional elements 22a. In the present 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 lattice shape. In addition, although the lines 15 are imaginary lines, they can also be actually drawn lines.

[0098] [Structure of laser irradiation unit]

[0099] Figure 4 Yes means Figure 1 A schematic diagram of the structure of the laser irradiation unit is shown. Figure 5 Yes means Figure 4 Diagram of the relay lens unit shown. Figure 6 yes Figure 4 A partial cross-sectional view of the spatial light modulator shown in FIG. 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 by, for example, pulse oscillation. In addition, the laser irradiation unit 3 may be configured without the light source 31, and the laser light L may be introduced from outside the laser irradiation unit 3.

[0100] The spatial light modulator 5 modulates the laser light L output from the light source 31. The condenser lens 33 condenses the laser light L modulated by the spatial light modulator 5. The 4f lens unit 34 has a pair of lenses 34A and 34B arranged on the optical path of the laser light L from the spatial light modulator 5 to the condenser lens 33. The pair of lenses 34A and 34B constitute a double-sided telecentric optical system in which the reflection surface 5a of the spatial light modulator 5 and the incident pupil surface (pupil surface) 33a of the condenser lens 33 are in an imaging relationship. As a result, the image of the laser light L on the reflection surface 5a of the spatial light modulator 5 (the image of the laser light L modulated in the spatial light modulator 5) is transferred (imaged) to the incident pupil surface 33a of the condenser lens 33.

[0101] The spatial light modulator 5 is a spatial light modulator (SLM: Spatial Light Modulator) of a reflective liquid crystal (LCOS: Liquid Crystal on Silicon). The spatial light modulator 5 is formed 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.

[0102] The semiconductor substrate 51 is, for example, a silicon substrate. The driving circuit layer 52 forms 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 along the surface of the semiconductor substrate 51. Each pixel electrode 53a is formed of, for example, a metal material such as aluminum. A voltage is applied to each pixel electrode 53a through the driving circuit layer 52.

[0103] The reflective film 54 is, for example, a dielectric multilayer film. The orientation film 55 is provided on the surface of the liquid crystal layer 56 on the reflective film 54 side, and the orientation film 57 is provided on the surface of the liquid crystal layer 56 on the opposite side to the reflective film 54. Each of the orientation films 55 and 57 is formed of a polymer material such as polyimide, and the contact surface of each of the orientation films 55 and 57 with the liquid crystal layer 56 is, for example, subjected to a rubbing treatment. The orientation films 55 and 57 align the liquid crystal molecules 56a contained in the liquid crystal layer 56 in a predetermined direction.

[0104] The transparent conductive film 58 is provided on the surface of the transparent substrate 59 on the side of the orientation film 57, and is opposite to 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-transmitting and conductive material such as ITO. The transparent substrate 59 and the transparent conductive film 58 allow the laser light L to pass through.

[0105] In the spatial light modulator 5 configured as described above, when a signal indicating a modulation pattern is input from the control unit 10 to the drive circuit layer 52, a voltage corresponding to the signal is applied to each pixel electrode 53a, thereby forming an electric field between each pixel electrode 53a and the transparent conductive film 58. When the electric field is formed, the arrangement direction of the liquid crystal molecules 216a in the liquid crystal layer 56 changes in each region corresponding to each pixel electrode 53a, thereby causing the refractive index to change in each region corresponding to each pixel electrode 53a. This state is a state in which the modulation pattern is displayed in the liquid crystal layer 56.

[0106] In a state where the liquid crystal layer 56 displays a modulation pattern, when the laser light L enters the liquid crystal layer 56 from the outside through 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 through the transparent conductive film 58 and the transparent substrate 59 to the outside, the laser light L is modulated according to the modulation pattern displayed on the liquid crystal layer 56. In this way, the spatial light modulator 5 can modulate the laser light L (for example, modulation of the intensity, amplitude, phase, polarization, etc. of the laser light L) by appropriately setting the modulation pattern displayed on the liquid crystal layer 56.

[0107] In the present embodiment, the laser irradiation unit 3 irradiates the wafer 20 with the laser light L from the back surface 21b side of the semiconductor substrate 21 along the plurality of lines 15, thereby forming two rows of modified regions 12a and 12b inside the semiconductor substrate 21 along the plurality of lines 15. The modified region (first modified region) 12a is the modified region closest to the surface 21a among the two rows of modified regions 12a and 12b. The modified region (second modified region) 12b is the modified region closest to the modified region 12a among the two rows of modified regions 12a and 12b, and is also the modified region closest to the back surface 21b.

[0108] The two rows of modified regions 12a and 12b are adjacent to each other in the thickness direction (Z direction) of the wafer 20. The two rows of modified regions 12a and 12b are formed by relatively moving the two focal points O1 and O2 along the line 15 with respect to the semiconductor substrate 21. The laser light L is modulated by the spatial light modulator 5 so that, for example, the focal point O2 is located at the rear side of the traveling direction relative to the focal point O1 and at the incident side of the laser light L.

[0109] As an example, the laser irradiation unit 3 can irradiate the wafer 20 with the laser light L from the back side 21b of the semiconductor substrate 21 along a plurality of lines 15, respectively, under the condition that the cracks 14 spanning the two rows of modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21. As an example, for the semiconductor substrate 21 which is a single crystal silicon substrate with a thickness of 775 μm, the two focal points O1 and O2 are focused at positions 54 μm and 128 μm from the surface 21a, respectively, and the wafer 20 is irradiated with the laser light L from the back side 21b of the semiconductor substrate 21 along a plurality of lines 15, respectively.

[0110] At this time, the wavelength of the laser L is 1099 nm, the pulse width is 700 nsec, and the repetition frequency is 120 kHz. Furthermore, the output of the laser L at the focal point O1 is 2.7 W, the output of the laser L at the focal point O2 is 2.7 W, and the relative moving speed of the two focal points O1 and O2 relative to the semiconductor substrate 21 is 800 mm / sec.

[0111] The formation of the two rows of modified regions 12a, 12b and the cracks 14 is performed in the following case. That is, in a subsequent process, the semiconductor substrate 21 is thinned by grinding the back surface 21b of the semiconductor substrate 21, and the cracks 14 are exposed on the back surface 21b, thereby cutting the wafer 20 into a plurality of semiconductor devices along the plurality of lines 15. However, as described below, the laser irradiation unit 3 may also form the modified regions (modified points) 12a, 12b and the cracks 14 extending from the modified regions 12a, 12b in the semiconductor substrate 21 in a manner that does not reach the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0112] [Structure of the camera unit]

[0113] Figure 7 Yes means Figure 1 The schematic diagram of the structure of the camera unit shown in FIG. Figure 7 As shown, the imaging unit 4 includes a light source 41, a reflector 42, an objective lens 43, and a light detection unit 44. The light source 41 outputs light I1 that is transmissive to the wafer 20 (at least to the semiconductor substrate 21). The light source 41 is composed of, for example, a halogen lamp and a filter, and outputs light I1 in the near-infrared region. The light I1 output from the light source 41 is reflected by the reflector 42 and passes through the objective lens 43, thereby irradiating the wafer 20 from the back side 21b of the semiconductor substrate 21. At this time, as described above, the stage 2 supports the wafer 20 on which the two rows of modified regions 12a and 12b are formed.

[0114] The objective lens 43 allows the light I1 reflected by the surface 21a of the semiconductor substrate 21 to pass through. That is, the objective lens 43 allows the light I1 propagating in the semiconductor substrate 21 to pass through. 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 the aberration caused by the light I1 in the semiconductor substrate 21, for example, by adjusting the distance between the multiple lenses constituting the objective lens 43. The light detection unit 44 detects the light I1 that penetrates the objective lens 43 and the reflector 42. The light detection unit 44 is composed of an infrared camera including an InGaAs camera, for example, and detects the light I1 in the near-infrared region. That is, the camera unit 4 is a component for photographing the semiconductor substrate 21 through the light I1 that is transparent to the semiconductor substrate 21. In addition, as a structure for correcting the aberration caused by the light I1, a spatial light modulator 5 or other structures can be used to replace the above-mentioned correction ring 43a, or a spatial light modulator 5 or other structures can be provided in addition to the above-mentioned correction ring 43a. Furthermore, the light detection unit 44 is not limited to the InGaAs camera, and may be any imaging device utilizing a transmission-type imaging such as a transmission-type confocal microscope.

[0115] The imaging unit 4 can capture images of each of the two rows of modified regions 12a and 12b, and the respective front ends of the plurality of cracks 14a, 14b, 14c, and 14d (details will be described later). The crack 14a is a crack extending from the modified region 12a to the surface 21a side. The crack 14b is a crack extending from the modified region 12a to the back surface 21b side. The crack 14c is a crack extending from the modified region 12b to the surface 21a side. The crack 14d is a crack extending from the modified region 12b to the back surface 21b side.

[0116] That is, the cracks 14b and 14d are first cracks extending from the modified regions 12a and 12b to the first surface, that is, the back surface 21b side, and the cracks 14a and 14c are second cracks extending from the modified regions 12a and 12b to the second surface, that is, the surface 21a side. Hereinafter, with the positive direction of the Z direction being upward, the crack 14d among the first cracks is sometimes referred to as an upper crack, and the crack 14a among the second cracks is sometimes referred to as a lower crack.

[0117] [Structure of the image pickup unit for alignment correction]

[0118] Figure 8 Yes means Figure 1 The schematic diagram of the structure of the camera unit shown in FIG. Figure 8 As shown, the imaging unit 7 includes a light source 71, a reflector 72, a lens 73, and a light detection unit 74. The light source 71 outputs light I2 that is transparent to the semiconductor substrate 21. The light source 71 is composed of, for example, a halogen lamp and a filter, and outputs light I2 in the near-infrared region. The light source 71 may also 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 reflector 72 and passes through the lens 73, thereby irradiating the wafer 20 from the back side 21b of the semiconductor substrate 21.

[0119] The lens 73 allows the light I2 reflected by the surface 21a of the semiconductor substrate 21 to pass through. That is, the objective lens 73 allows the light I2 propagating in the semiconductor substrate 21 to pass through. The numerical aperture of the lens 73 is less than 0.3. That is, the numerical aperture of the objective lens 43 of the imaging unit 4 is larger than the numerical aperture of the lens 73. The light detection unit 74 detects the light I2 passing through the lens 73 and the reflector 72. The light detection unit 74 is composed of an infrared camera including an InGaAs camera, for example, and detects the light I2 in the near-infrared region.

[0120] The imaging unit 7 irradiates the wafer 20 with light I2 from the back side 21b according to the control of the control unit 10, and detects the light I2 returned from the surface 21a (functional element layer 22), thereby capturing an image of the functional element layer 22. Also, the imaging unit 7 irradiates the wafer 20 with light I2 from the back side 21b according to the control of the control unit 10, and detects the light I2 returned from the formation position of the modified regions 12a and 12b of the semiconductor substrate 21, thereby obtaining an image of the region including the modified regions 12a and 12b. These images are used to align the irradiation position of the laser L. The imaging unit 8 has the same structure as the imaging unit 7 except that the magnification is lower than that of the lens 73 (for example, 6 times in the imaging unit 7 and 1.5 times in the imaging unit 8), and is used for alignment in the same manner as the imaging unit 7. Furthermore, the imaging means 4, 7, and 8 may be used in common for imaging for acquiring the formation state as described later and imaging for alignment as described above.

[0121] [Image capture principle of the image capture unit]

[0122] like Fig. 9 As shown in FIG. 1 , the imaging unit 4 is used to move the focus F (the focus of the objective lens 43) from the back surface 21b side to the front surface 21a side of the semiconductor substrate 21 where the crack 14 (the crack extending from the modified point) spanning the two rows of modified regions 12a and 12b reaches the surface 21a. In this case, if the focus F is focused on the front end 14e of the crack 14 extending from the modified region 12b to the back surface 21b side from the back surface 21b side, the front end 14e ( Fig. 9 However, even if the focus F is focused on the crack 14 itself and the front end 14e of the crack 14 reaching the surface 21a from the back side 21b, it is not possible to confirm ( Fig. 9 In addition, if the focus F is focused on the front surface 21a of the semiconductor substrate 21 from the back surface 21b side, the functional element layer 22 can be confirmed.

[0123] And, if Fig.10 As shown in FIG. 1 , the imaging unit 4 is used to move the focus F from the back surface 21b side to the front surface 21a side of the semiconductor substrate 21 in which the crack 14 extending across the two rows of modified regions 12a and 12b has not reached the front surface 21a. In this case, even if the focus F is focused on the front end 14e of the crack 14 extending from the modified region 12a to the front surface 21a side from the back surface 21b side, the front end 14e cannot be confirmed ( Fig.10 However, if the focus F is focused on the area on the opposite side of the back surface 21b relative to the surface 21a (i.e., the area on the functional element layer 22 side relative to the surface 21a) from the back surface 21b side, and an imaginary focus Fv symmetrical to the focus F with respect to the surface 21a is positioned at the front end 14e, it can be confirmed that the front end 14e ( Fig.10 ). In addition, the virtual focus Fv is a point symmetrical to the focus F with respect to the surface 21a, wherein the refractive index of the semiconductor substrate 21 has been taken into consideration.

[0124] It is speculated that the reason why the cracks 14 cannot be confirmed as described above is that the width of the cracks 14 is smaller than the wavelength of the light I1 as the illumination light. Fig.11 and Fig.12 This is a SEM (Scanning Electron Microscope) image of the modified region 12 and the cracks 14 formed inside the semiconductor substrate 21 which is a silicon substrate. Fig.11 (b) is Fig.11 The enlarged image of the area A1 shown in (a) is Fig.12 (a) is Fig.11 (b) shows an enlarged image of region A2, Fig.12 (b) is Fig.12 This is an enlarged image of the region A3 shown in (a) of FIG. 1. Thus, the width of the crack 14 is about 120 nm, which is smaller than the wavelength (for example, 1.1 to 1.2 μm) of the light I1 in the near-infrared region.

[0125] The camera principle based on the above assumptions is as follows. Fig.13 As shown in (a), if the focus F is placed in the air, the light I1 will not return, so a dark image will be obtained ( Fig.13 (a) is the image on the right side of the image). Fig.13 As shown in (b), if the focus F is located inside the semiconductor substrate 21, the light I1 reflected by the surface 21a will return, so a white image will be obtained ( Fig.13 (b) on the right). Fig.13 As shown in (c), if the focus F is focused on the modified region 12 from the back side 21b, part of the light I1 reflected by the surface 21a and returned will be absorbed or scattered by the modified region 12, so an image showing the modified region 12 as dark against a white background will be obtained ( Fig.13 (c) is the right image of the image).

[0126] like Fig.14 As shown in (a) and (b), if the focus F is focused on the front end 14e of the crack 14 from the back side 21b, the light is confined near the front end 14e due to optical specificity (stress concentration, distortion, discontinuity of atomic density, etc.) generated near the front end 14e, and part of the light I1 reflected by the surface 21a and returned is scattered, reflected, interfered, absorbed, etc., so an image showing the dark front end 14e against a white background is obtained ( Fig.14 (a) and (b) on the right). Fig.14 As shown in (c), if the focus F is focused on the portion other than the vicinity of the front end 14e of the crack 14 from the back side 21b, at least a part of the light I1 reflected by the surface 21a will return, so a white image will be obtained ( Fig.14 (c) is the right image of the image).

[0127] [Inspection principle of the camera unit]

[0128] The control unit 10 controls the laser irradiation unit 3 to irradiate the laser light L under the condition that the crack 14 spanning the two rows of modified regions 12a and 12b reaches the surface 21a of the semiconductor substrate 21, so that as expected, when the crack 14 spanning the two rows of modified regions 12a and 12b reaches the surface 21a, the state of the front end 14e of the crack 14 becomes as follows. That is, Fig.15 As shown, the front end 14e of the crack 14 does not appear in the area between the modified region 12a and the surface 21a, and in the area between the modified region 12a and the modified region 12b. The position of the front end 14e of the crack 14 extending from the modified region 12b to the back surface 21b side (hereinafter simply referred to as "front end position") is located on the back surface 21b side relative to the reference position P between the modified region 12b and the back surface 21b.

[0129] On the other hand, the control unit 10 controls the state of the front end 14e of the crack 14 to be as follows when the crack 14 that spans the two rows of modified regions 12a and 12b does not reach the surface 21a. Fig.16 As shown, in the region between the modified region 12a and the surface 21a, the front end 14e of the crack 14a extending from the modified region 12a to the surface 21a side appears. In the region between the modified region 12a and the modified region 12b, the front end 14e of the crack 14b extending from the modified region 12a to the back surface 21b side and the front end 14e of the crack 14c extending from the modified region 12b to the surface 21a side appear. The front end position of the crack 14 extending from the modified region 12b to the back surface 21b side is located on the surface 21a relative to the reference position P between the modified region 12b and the back surface 21b.

[0130] As described above, by causing the control unit 10 to perform at least one of the following first inspection, second inspection, third inspection, and fourth inspection, it is possible to evaluate whether the cracks 14 spanning the modified regions 12a and 12b of the two columns have reached the surface 21a of the semiconductor substrate 21. The first inspection is an inspection for determining whether the front end 14e of the crack 14a extending from the modified region 12a to the surface 21a side is present in the inspection region R1, with the region between the modified region 12a and the surface 21a being the inspection region R1.

[0131] The second inspection is to determine whether the front end 14e of the crack 14b extending from the modified region 12a to the back surface 21b side is present in the inspection region R2, using the region between the modified region 12a and the modified region 12b as the inspection region R2. The third inspection is to determine whether the front end 14e of the crack 14c extending from the modified region 12b to the surface 21a side is present in the inspection region R2. The fourth inspection is to determine whether the front end position of the crack 14 extending from the reference position P to the back surface 21b side but not reaching the back surface 21b is located in the inspection region R3, using the region extending from the reference position P to the back surface 21b side but not reaching the back surface 21b as the inspection region R3.

[0132] In addition, through the above inspection, not only the information on whether the front end 14e of the crack 14 exists in the predetermined area can be obtained, but also the information on the formation state of the modified area and the crack, such as the position of each front end 14e, the position of the modified area 12a and 12b, the length of the cracks 14a to 14d, and the overall length of the crack 14, can be obtained. As described above, the cracks 14b and 14d are the first cracks extending to the first surface, that is, the back side 21b, and their front ends 14e are the front ends, that is, the first ends, on the back side 21b of the first crack. In particular, the crack 14d is an upper crack. And the cracks 14a and 14c are the second cracks extending to the second surface, that is, the surface 21a side, and their front ends 14e are the front ends, that is, the second ends, on the surface 21a side of the second crack. In particular, the crack 14a is a lower crack.

[0133] [How to obtain the formation status]

[0134] Next, a method for acquiring information on the formation state of the modified region and the cracks will be described. Fig.17 This is a cross-sectional view of an object used to explain the method of obtaining the formed state. Fig.17 The functional element layer 22 of the wafer 20 is omitted. Fig.17 In the figure, virtual images 12aI, 12bI, 14aI, 14bI, 14cI and 14dI are respectively illustrated for the modified region 12a, the modified region 12b, the cracks 14a, the cracks 14b, the cracks 14c and the cracks 14d, which are symmetrically positioned relative to the surface 21a.

[0135] And, in Fig.17The figure shows the modified regions 12a and 12b extending in a single direction. As described above, each of the modified regions 12a and 12b includes a set of modified points 12s. Therefore, the cracks 14a to 14d extending from the modified regions 12a and 12b are the cracks 14a to 14d extending from the modified points 12s. In particular, in the cross section intersecting the extending direction of the modified regions 12a and 12b, the modified regions 12a and 12b are the same as the single modified points 12s. Therefore, the modified regions 12a and 12b can also be interpreted as the modified points 12s.

[0136] In the wafer 20, the following are formed in a manner that does not reach the outer surfaces (surface 21a, back side 21b): modified regions 12a and 12b, a crack 14a (lower crack) extending from the modified region 12a toward the surface 21a side, a crack 14b extending from the modified region 12a toward the back side 21b side, a crack 14c extending from the modified region 12b toward the surface 21a side, and a crack 14d (upper crack) extending from the modified region 12b toward the back side 21b side.

[0137] In addition, Fig.17 In the example, the crack 14b and the crack 14c are connected to each other to form a single crack, but they may be separated from each other. Also, the front end 14e of the back surface 21b side of the crack 14d (upper crack) is sometimes referred to as the first end (upper crack front end) 14de, and the front end 14e of the surface 21a side of the crack 14a (lower crack) is sometimes referred to as the second end (lower crack front end) 14ae.

[0138] The formation state of the modified regions 12a, 12b and the cracks 14a to 14d includes a plurality of items. An example of the items included in the formation state (hereinafter referred to as the formation state items) is as follows. In addition, the Z direction described below is an example of a first direction that intersects (is perpendicular to) the surface 21a and the back surface 21b. In addition, for the convenience of explanation, the following individual formation state items are marked with unillustrated symbols. In addition, each value is a value with the surface 21a as the reference position (0 point).

[0139] Upper crack front end position F1: the position of the first end 14 de in the Z direction.

[0140] Upper crack amount F2: length of the crack 14d in the Z direction.

[0141] Lower crack front end position F3: the position of the second end 14ae in the Z direction.

[0142] Lower crack amount F4: length of the crack 14a in the Z direction.

[0143] Total crack amount F5: The total amount of lengths of the cracks 14a to 14d in the Z direction, and is the distance between the first end 14de and the second end 14ae in the Z direction.

[0144] Vertical crack tip position deviation width F6: deviation width between the position of the first end 14 de and the position of the second end 14 ae in a direction (Y direction) intersecting (orthogonal) the machining advancing direction (X direction).

[0145] Presence or absence of marks on the modified regions F7: Presence or absence of marks on the modified points constituting the respective modified regions 12a and 12b.

[0146] The meandering amount F8 of the front end of the lower crack is the meandering amount of the second end 14ae in the Y direction.

[0147] The presence or absence of black lines between modified regions F9: The presence or absence of the front end of the back surface 21b side of the crack 14b and the front end of the surface 21a side of the crack 14c in the 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 and 14c are present, black lines are observed (corresponding to "presence of black lines"); when the front ends of the cracks 14b and 14c are not present (connected), no black lines are observed (corresponding to "no black lines").

[0148] In order to acquire the formation state including the above-mentioned formation state items, the following images C1 to C11 can be performed by the light I1 of the imaging unit 4 .

[0149] Image C1: The semiconductor substrate 21 is imaged by light I1 so that the focus F of the objective lens 43 of the image pickup unit 4 is focused on the first end 14de of the fissure 14d. At this time, the position in the Z direction (the position based on the back surface 21b) where the focus F is focused can be obtained as position P1.

[0150] Image C2: The semiconductor substrate 21 is imaged by light I1 so that the focus F is focused on the front end of the rear surface 21b of the modified region 12b. At this time, the position in the Z direction (the position based on the rear surface 21b) where the focus F is focused can be obtained as position P2.

[0151] Image C3: The semiconductor substrate 21 is imaged by light I1 so that the focus F is focused on the tip of the back surface 21b side of the crack 14b. At this time, the position in the Z direction where the focus F is focused (the position based on the back surface 21b) can be obtained as position P3.

[0152] Image C4: The semiconductor substrate 21 is imaged by light I1 so that the focus F is focused on the front end of the rear surface 21b side of the modified region 12a. At this time, the position in the Z direction (the position based on the rear surface 21b) where the focus F is focused can be obtained as position P4.

[0153] Image C5: The semiconductor substrate 21 is photographed by light I1 in such a manner that the focus F is focused on the second end 14ae of the fissure 14a from the surface 21a side (so that the focus F is focused on the front end of the virtual image 14aI). At this time, the position in the Z direction (the position based on the back surface 21b) where the focus F is focused can be obtained as position P5I. Position P5I is a position corresponding to the front end of the virtual image 14aI, so it is a position outside the semiconductor substrate 21 (below the surface 21a). And by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to position P5I, the position P5 of the second end 14ae of the fissure 14a (real image) can be obtained.

[0154] Image C6: The semiconductor substrate 21 is photographed by light I1 in such a manner that the focus 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 F is focused on the front end of the virtual image 12aI). At this time, the position in the Z direction (the position based on the back surface 21b) where the focus F is focused can be obtained as the position P6I. The position P6I is the position corresponding to the front end of the virtual image 12aI, so it is a position outside the semiconductor substrate 21 (lower than the surface 21a). And, by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P6I, the position P6 of the front end of the modified region 12a (real image) can be obtained. And, the position P6 can also be obtained by multiplying the Z height by the DZ ratio, where the Z height is the amount of movement of the objective lens 43 in the Z direction when the modified region 12a is formed, and the DZ ratio is a coefficient for considering the refractive index of the material (for example, silicon) of the semiconductor substrate 21.

[0155] Image capture C7: The semiconductor substrate 21 is imaged by the light I1 while the focus F is scanned in a range P7 between the position P1 and the position P2.

[0156] Image capture C8: The semiconductor substrate 21 is imaged by the light I1 while the focus F is scanned in the range P8 between the position P5 and the position P6.

[0157] Image capture C9: The semiconductor substrate 21 is imaged by the light I1 while the focus F is scanned in the range P9 between the modified region 12a and the modified region 12b.

[0158] Image capture C10: The semiconductor substrate 21 is imaged by the light I1 while the focus F is scanned over a range P10 extending over the front end on the rear surface 21b side of the modified region 12a.

[0159] Image C11: The semiconductor substrate 21 is photographed by light I1 in such a manner that the focus F is focused on the front end of the surface 21a side of the modified region 12b from the surface 21a side (in such a manner that the focus F is focused on the front end of the virtual image 12bI). At this time, the position in the Z direction (the position based on the back surface 21b) where the focus F is focused can be obtained as the position P11I. The position P11I is the position corresponding to the front end of the virtual image 12bI, so it is the position outside the semiconductor substrate 21 (lower than the surface 21a). And, by subtracting the thickness T of the semiconductor substrate 21 from the distance from the back surface 21b to the position P11I, the position P11 of the front end of the modified region 12b (real image) can be obtained. In addition, the position P11 can also be obtained by multiplying the Z height by the DZ ratio, where the Z height is the amount of movement of the objective lens 43 in the Z direction when the modified region 12b is formed, and the DZ ratio is a coefficient for considering the refractive index of the material (for example, silicon) of the semiconductor substrate 21.

[0160] As described below, the above-mentioned respective formation state items are acquired by performing the above-mentioned imaging C1 to C10.

[0161] Upper crack front end position F1: a value obtained by subtracting the distance between the position P1 obtained by imaging C1 and the back surface 21 b from the thickness T of the semiconductor substrate 21 (T−P1) is obtained.

[0162] Upper crack amount F2: A value obtained by subtracting the distance between the position P1 and the back surface 21b from the distance between the position P2 and the back surface 21b acquired by the imaging C2 (P2-P1) is obtained.

[0163] Lower crack front end position F3: As described above, a value is obtained by subtracting the thickness T of the semiconductor substrate 21 from the distance between the position P5I obtained by imaging C5 and the rear surface 21b (P5I-T=P5).

[0164] Lower crack amount F4: As described above, the value (P5-P6) is obtained by subtracting "the value obtained by imaging C6 and the distance from the position P6I to the back surface 21b minus the thickness T of the semiconductor substrate 21 (P6I-T=P6)" from the position P5.

[0165] Total crack amount F5: A distance obtained by subtracting a value (P5-P1) between the distance between the position P5 and the back surface 21b and the distance between the position P1 and the back surface 21b is obtained.

[0166] Vertical crack tip position deviation width F6: can be measured from an image acquired in the range P10 by the imaging C10.

[0167] Whether there are marks on the modified area F7: For the modified area 12b, it can be judged by the image obtained by camera C2 at position P2 or the image obtained by camera C11 at position P11 (position P11I); for the modified area 12a, it can be judged by the image obtained by camera C4 at position P4 or the image obtained by camera C6 at position P6 (position P6I).

[0168] The meandering amount F8 of the front end of the lower crack can be measured from the image acquired at the position P5 (position P5I) by the imaging C5.

[0169] The presence or absence of black lines between modified regions F9 can be determined from the image acquired in the range P9 by the camera C9 (when the tips of the cracks 14b and 14c are confirmed in the image acquired in the range P9, it can be determined that "black lines exist").

[0170] [Relationship between irradiation conditions and formation state]

[0171] When forming the modified regions 12a and 12b, if the irradiation conditions of the laser L are changed, the formation state of the modified regions 12a and 12b and the cracks 14a to 14d may also change. Next, the correlation between the irradiation conditions of the laser L and the formation state of the modified regions 12a and 12b and the cracks 14a to 14d will be described by taking the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 among the formation state items as examples.

[0172] First, the irradiation conditions of the laser L used to form the modified regions 12a and 12b include a plurality of items. An example of the items included in the irradiation conditions (hereinafter referred to as "irradiation condition items") is as follows. In addition, for the convenience of explanation, each of the following irradiation condition items is marked with a non-illustrated symbol.

[0173] Modified region interval D1: the interval between the modified region 12a and the modified region 12b in the Z direction.

[0174] Pulse width D2: The pulse width of laser L.

[0175] Pulse energy D3: Pulse energy of laser L.

[0176] Pulse interval D4: pulse interval of laser L.

[0177] Converged state D5: This is the converged state of the laser light, and an example thereof is the spherical aberration correction level D6, the astigmatism correction level D7, and the LBA deviation amount D8 (described later).

[0178] Fig.18 and Fig.19This is a graph showing changes in the amount of cracking when the modified region interval is changed at three points. Fig.18 The horizontal axis of the graphs (a) and (b) represents the modified region interval D1 in terms of Z height. The three points of the modified region interval D1 are level 4, level 8, and level 12, and each corresponds to Fig.19 (a), (b) and (c). In addition, Fig.19 It is the cutting surface.

[0179] like Fig.18 and Fig.19 As shown, in the processing of either the forward path or the return path, as the modified region interval D1 increases, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also increase. In addition, as an example, the case where the focal point of the laser L moves in the positive X direction (the processing direction is the positive X direction) is called processing on the forward path, and the case where the focal point of the laser L moves in the negative X direction (the processing direction is the negative X direction) is called processing on the return path.

[0180] Fig. 20 and Fig.21 Graph showing the change in the amount of cracking when the pulse width of the laser is changed at three points. The three points of pulse width D2 are level 2, level 3, and level 5, and each corresponds to Fig.21 (a), (b) and (c). In addition, Fig.21 is the cutting surface. Fig. 20 , 21 As shown in the figure, as the pulse width D2 increases, the upper crack amount F2, the lower crack amount F4 and the total crack amount F5 also increase. However, for the total crack amount F5, when the pulse width D2 is level 2, a black line is generated between the modified region 12a and the modified region 12b (there is a black line between the modified regions), so that the total crack amount F5 cannot be measured by the camera unit 4 (from the observation of the cut surface, it can be seen that the total crack amount F5 is located in region A).

[0181] Fig. 22 and Fig.23 Graph showing the change in the amount of cracking when the pulse energy of the laser is changed at three points. The three points of pulse energy D3 are level 2, level 7, and level 12, and each corresponds to Fig.23 (a), (b) and (c). In addition, Fig.23 is the cutting surface. Fig. 22 , 23 As 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.

[0182] Fig.24 and Fig.254 is a graph showing the change in the amount of cracking when the pulse interval of the laser 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 Fig.24 (a), (b), (c) and (d). In addition, Fig.25 is the cutting surface. Fig.24 and Fig.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.

[0183] In particular, in the lower crack amount F4 on the outgoing and return paths, the upper crack amount F2 on the return path, and the total crack amount F5 on the return path, peak values ​​appear in the pulse interval D4 at four points. However, for the total crack amount F5, when the pulse interval D4 is level 6.7, a black line is generated between the modified area 12a and the modified area 12b (a black line exists between the modified areas), and the total crack amount F5 cannot be measured by the camera unit 4 (from the observation of the cut surface, it can be seen that the total crack amount F5 is located in area B).

[0184] Fig.26 and Fig. 27 The figure shows the change in the amount of cracking when the focusing state of the laser light (spherical aberration correction level) 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 Fig. 27 (a), (b) and (d). In addition, Fig. 27 is the cutting surface. Fig.26 and Fig. 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.

[0185] Fig.28 and Fig.29 Graph showing the change in the amount of cracking when the focusing state of the laser light (astigmatism correction level) 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 Fig.28 (a), (b) and (d). In addition, Fig.29 is the cutting surface. Fig.28 and Fig.29 As shown in FIG. 1 , as the astigmatism correction level D7 changes, the upper crack amount F2, the lower crack amount F4, and the total crack amount F5 also change. In particular, in addition to the upper crack amount F2 on the forward and return paths, peak values ​​are shown in the astigmatism correction level D7 at three points.

[0186] Fig.30 and Fig.311 is a graph showing the change in the presence or absence of black lines when the pulse interval of the laser 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 Fig.30 and 31 (a), (b), (c) and (d). In addition, Fig.31 Cutting surface. Fig.30 As shown, when the pulse interval D4 is level 6.7, the front ends of the cracks 14b and 14c are confirmed (refer to Fig.30 In fact, if Fig.31 As shown in (d) of FIG. 1 , in observation of the cut surface, it can be confirmed that a black line Bs is generated between the modified region 12a and the modified region 12b.

[0187] As described above, there is a correlation between the irradiation conditions of the laser L and the formation state of the modified regions 12a, 12b and the cracks 14a to 14d. Therefore, after the modified regions 12a, 12b are formed, by taking images with the imaging unit 4 to obtain various items of the formation state, it is possible to determine whether the irradiation conditions of the laser L are acceptable or to derive the preferred irradiation conditions of the laser L.

[0188] [Embodiments of Laser Processing Device]

[0189] Next, an embodiment of the laser processing device 1 will be described. Here, an example of an operation for determining whether the irradiation conditions of the laser light L are acceptable will be described. Fig.32 1 is a flowchart showing the main steps of the pass / fail determination method. The following method is a first embodiment of the laser processing method. Here, first, the control unit 10 of the laser processing device 1 receives input from the user (step S1). Step S1 is described in more detail.

[0190] Fig.33 Yes means Figure 1 An example of an input receiving unit is shown in FIG. Fig.33As shown in (a), in step S1, first, the control unit 10 displays information H1 for guiding the user to select whether to perform machine difference-wafer correction inspection and information H2 for guiding the user to select the inspection content by controlling the input receiving unit 103. The so-called "machine difference-wafer correction inspection" is a mode in which the irradiation (processing) of the laser L is performed under predetermined irradiation conditions to judge whether the irradiation conditions are qualified or not, because the irradiation conditions of the laser L used to achieve the required formation state of the modified regions 12a, 12b and the cracks 14a to 14d will vary depending on the machine differences of the laser processing device 1 and the wafer. In addition, in the following description, the formation state of the modified regions 12a, 12b and the cracks 14a to 14d is sometimes referred to as simply "formation state", and the irradiation conditions of the laser L are sometimes referred to as simply "irradiation conditions".

[0191] And, as information H2 for guiding the selection of the inspection content, Fig.33 As shown in (b), a plurality of inspection contents H21 to H24 are displayed, each of which is a group of processing position, processing condition and wafer thickness. The processing position is the position from the incident surface of the 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 which cracks do not reach the outer surface (ST) at a predetermined wafer thickness and processing position.

[0192] Next, in step S1, the input receiving unit 103 receives the user's selection of whether to perform the machine difference-wafer calibration inspection. Also, in step S1, the input receiving unit 103 receives the selection of the inspection contents H21 to H24, etc. Next, in step S1, when the input receiving unit 103 receives the selection of performing the machine difference-wafer calibration inspection and the selection of the inspection contents H21 to H24, etc., the control unit 10 sets the processing conditions (including the irradiation conditions of the laser L) corresponding to the inspection contents H21 to H24, etc. as the basic processing conditions.

[0193] Fig.34 1 is a diagram showing an input receiving unit in a state where an example of basic processing conditions is displayed. Fig.34 As shown, in step S1, when the input receiving unit 103 receives the selection of executing the machine difference-wafer calibration inspection and the selection of the inspection contents H21 to H24, the control unit 10 controls the input receiving unit 103 to display the information H3 indicating the set basic processing conditions on the input receiving unit 103. The information H3 indicating the basic processing conditions includes a plurality of items.

[0194] Among the multiple items, the item H31 indicating the execution of machine difference-wafer calibration inspection, the processing condition H32, the wafer thickness H33 and the processing position H34 first indicate the selection results of the inspection contents H21 to H24, etc., and currently do not accept selections from the user. On the other hand, the number of focal points H41, the number of scans 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 that the control unit 10 prompts as an example of basic processing conditions, and currently can accept selections (changes) from the user.

[0195] In addition, the number of focal points H41 indicates the number of branches of the laser light L (the number of focal points), the number of scans H42 indicates the number of times the laser light L is scanned along the line, and the processing speed H43 indicates the relative speed of the focal point of the laser light L. Therefore, the pulse interval of the laser light L can be specified by the processing speed H43 and the (repetition) frequency H45 of the laser light L. On the other hand, the judgment item H47 displays the formation status item for judging whether the irradiation condition of the laser light L is qualified or not among the above-mentioned multiple formation status items.

[0196] Here, as the judgment item H47, one example is to set the crack amount (lower side), that is, the lower crack amount F4 (other formation state items can also be selected). In addition, the target value H48 is a value representing the center of the qualified range of the irradiation conditions of the laser L, and the specification H49 is a value representing the upper and lower widths of the value (target value H48) from the center of the qualified 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 (other ranges can also be selected) are set in such a way that the irradiation conditions of the laser L are judged to be qualified.

[0197] The above is step S1, which sets the basic processing conditions for laser processing. In the next step, the control unit 10 performs the fourth process (step S2), that is, it determines whether the basic processing conditions set as irradiation conditions in step S1 are actually conditions that prevent the cracks 14a and 14d from reaching the outer surface (surface 21a and back surface 21b), that is, non-reaching conditions (ST conditions). Here, the control unit 10 (without video recording) refers to the database to determine whether the accepted input conditions are non-reaching conditions. As an example, the control unit 10 can determine "whether the focusing position corresponding to the processing position of the accepted input is too close to the surface 21a to become a condition (BHC condition) for the cracks 14a to reach the surface 21a, etc."

[0198] In the next step, when the result of the judgment in step S2 indicates that the basic processing condition is not reached (step S2: YES), processing is performed according to the basic processing condition set in step S1 (step S3, first step). Here, the control unit 10 performs the first process, that is, by controlling the laser irradiation unit 3 to irradiate the semiconductor substrate 21 with the laser light L, the modified regions 12a, 12b and the cracks 14a to 14d extending from the modified regions 12a, 12b are formed in the semiconductor substrate 21 in such a manner that the laser light L does not reach the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21. More specifically, in step S3, the control unit 10 controls the laser irradiation unit 3 and the stage 2 to relatively move the light-converging points O1, O2 of the laser light L in the X direction while the light-converging points O1, O2 are located inside the semiconductor substrate 21, thereby forming the modified regions 12a, 12b and the cracks 14a to 14d inside the semiconductor substrate 21. If the result of the determination in step S2 indicates that the basic processing condition is not an unreached condition (step S2: NO), the process returns to step S1 and the irradiation condition is set again.

[0199] Next, the control unit 10 performs the second processing (step S4, the second step), that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed with the light I1 having the ability to transmit the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a-14b. Here, since the lower crack amount F4 is specified as the judgment item H47 in step S1, at least the imaging C5 and the imaging C6 necessary for obtaining the lower crack amount F4 are performed (other imaging may also be performed).

[0200] Next, the control unit 10 performs the following processing (step S5): that is, by controlling the input receiving unit 103, the information indicating the irradiation conditions of the laser L in the step S3 (first processing) and the information indicating the formation status obtained in the step S4 (second processing) are associated with each other and displayed on the input receiving unit 103. The information indicating the formation status (formation status item) displayed in the step S5 is the lower crack amount F4 of the judgment item H47 set in the step S1 (other formation status items may also be displayed together). As described above, the judgment item H47 can be selected.

[0201] Therefore, in step S1, the control unit 10 performs the following processing: that is, by controlling the input receiving unit 103, the input receiving unit 103 displays information that guides the user to select the formation status item displayed on the input receiving unit 103 in step S5 from among the plurality of formation status items. In addition, the input receiving unit 103 receives the selection of the formation status item in step S1. Next, in step S5, the control unit 10 controls the input receiving unit 103 to associate the information indicating the formation status item (here, the lower crack amount F4) received by the input receiving unit 103 with the information indicating the irradiation condition of the laser L (here, the pulse energy D3) and displays the information on the input receiving unit 103.

[0202] Furthermore, the control unit 10 may also perform the following processing: that is, by controlling the input receiving unit 103, the input receiving unit 103 is caused to display information guiding the selection of the irradiation condition item displayed on the input receiving unit 103 in step S5 from among the plurality of irradiation condition items included in the irradiation condition of the laser L. When this processing is performed, the input receiving unit 103 receives the input of the selection of the irradiation condition item, and the control unit 10 controls the input receiving unit 103 to associate the information indicating the irradiation condition item received by the input receiving unit 103 from among the irradiation conditions with the information indicating the forming state and displays the information on the input receiving unit 103.

[0203] In the next step, the control unit 10 performs a third process (step S6, the third process): that is, based on the information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a-14b obtained in step S4, the control unit 10 determines whether the irradiation conditions of the laser L in step S3 (the first process) are qualified. More specifically, the lower crack amount F4 of the judgment item H47 set in step S1, the target value H48 is 40μm, and the specification is ±5μm, so when the lower crack amount F4 obtained in step S4 is in the range of 35μm or more and 45μm or less, the control unit 10 determines that the irradiation conditions of the laser L in step S3 are qualified.

[0204] As described above, the judgment item H47 can be selected. Therefore, in step S1, the control unit 10 performs the tenth process: that is, by controlling the input receiving unit 103, information for guiding the selection of the item for passing or failing judgment, that is, the judgment item H47, from among the plurality of forming state items included in the forming state is displayed on the input receiving unit 103. And, the input receiving unit 103 receives the selection of the judgment item H47 in step S1. Next, the control unit 10 performs the passing or failing judgment based on the information indicating the judgment item H47 received by the input receiving unit 103.

[0205] Furthermore, as described above, the target value H48 and the specification H49 can be selected. Therefore, in step S1, the control unit 10 performs the seventh process: that is, by controlling the input receiving unit 103, the input receiving unit 103 displays information for guiding the input of the target value H48 and the specification H49 of the formation state. Furthermore, the input receiving unit 103 receives the input of the target value H48 and the specification H49 in step S1. Furthermore, in step S6, the control unit 10 performs a pass / fail judgment by comparing the formation state (lower crack amount F4) under the irradiation conditions of step S3 with the target value H48 and the specification H49.

[0206] When the result of step S6 is a qualified result (step S6: YES), the control unit 10 controls the input receiving unit 103 to perform the sixth process (step S7) of displaying the qualified judgment result (the result of the pass / fail judgment) on the input receiving unit 103, and then determines whether to end the pass / fail judgment (step S8). In this step S8, the control unit 10 controls the input receiving unit 103 to display information guiding the selection of whether to end the pass / fail judgment on the input receiving unit 103, and when the input receiving unit 103 receives an input to end the pass / fail judgment (step S8: YES), the processing ends. On the other hand, in this step S8, when the input receiving unit 103 receives an input to perform a re-judgment without ending the pass / fail judgment (step S8: NO), the process moves to step S10 described later. This is because even when the control unit 10 determines that the result is acceptable, there may be a situation where the control unit 10 wishes to set a favorable condition that is further away from being unacceptable and requests to continue the pass / fail determination.

[0207] On the other hand, when the result of step S6 is an unqualified result (step S6: No), the control unit 10 controls the input receiving unit 103 to execute the sixth processing (step S9) of displaying the judgment result indicating unqualified (the result of the qualified or unqualified judgment) on the input receiving unit 103, and re-judgments the processing after correcting at least one of the multiple irradiation condition items as a correction item and re-executing the first processing.

[0208] The re-judgment is described in more detail. When the result of the pass / fail judgment in step S6 is unqualified, and when an input for re-judgment is received in step S8, the control unit 10 controls the input receiving unit 103 to calibrate at least one of the multiple irradiation condition items included in the irradiation condition as a correction item, and re-judgment of the processing after the first processing is executed again. That is, the situation of re-judgment is not limited to the situation where the result of the pass / fail judgment is unqualified. In other words, here, re-judgment is performed based on the result of the pass / fail judgment in step S6. In addition, it can also be: the control unit 10 executes the eighth processing of displaying the information input receiving unit 103 that guides the selection of whether to "calibrate at least one of the multiple irradiation condition items included in the irradiation condition as a correction item and re-judgment", and when the input receiving unit 103 receives the selection for re-judgment, re-judgment is performed.

[0209] Therefore, first of all, Fig.35 As shown, the control unit 10 performs the ninth process (step S10), that is, by controlling the input receiving unit 103, the input receiving unit 103 displays information for guiding the selection of the correction item H5. The correction item H5 can be selected from the above-mentioned irradiation condition items, for example. In addition, at the same time as the correction item H5, the control unit 10 can display information for guiding the selection of the judgment item H47 and the processing condition H32 on the input receiving unit 103. And, the input receiving unit 103 at least accepts the user's selection of the correction item H5 (step S10).

[0210] Then, if Fig.36 As shown, the control unit 10 controls the input receiving unit 103 to display the correction item H5 of the selection result received by the input receiving unit 103 as a setting screen H6 of the variable condition on the input receiving unit 103. An example of the setting screen H6 is a screen in the case where the pulse energy D3 is selected as the correction item H5. Therefore, the pulse energy H46 is displayed as a variable condition. Here, the value of the basic processing condition is displayed as the pulse energy H46, the range of 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.

[0211] Furthermore, in the setting screen H6, a maximum value is displayed as an adjustment method H63. Therefore, in the following re-judgment, the result of irradiation (processing) of the laser L with three different pulse energies D3 within the range of level 10, when multiple pulse energies D3 are not judged as qualified, the pulse energy D3 that obtains the largest lower crack amount F4 is displayed as an adjustment candidate. In addition, in the setting screen H6, the user can currently select items other than the correction item H5, the judgment item H47, and the wafer thickness H33. Furthermore, the control unit 10 sets the irradiation conditions and the like displayed on the setting screen H6 as conditions for re-judgment. Furthermore, in the adjustment method H63, the minimum value or the average value can be selected instead of the maximum value according to the irradiation conditions.

[0212] Next, the control unit 10 performs processing according to the conditions displayed on the setting screen H6 (process S11, the first process). That is, in the following process, the control unit 10 calibrates the correction item H5 received by the input receiving unit 103 and re-judges. In this process S11, the control unit 10 performs the first process: that is, by controlling the laser irradiation unit 3, the laser L is irradiated to the semiconductor substrate 21, and the modified regions 12a, 12b and the cracks 14a to 14d extending from the modified regions 12a, 12b are formed in the semiconductor substrate 21 in a manner that does not reach the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21. In particular, here, when the pulse energy as the correction item H5 is 3 different values, the processing is performed separately.

[0213] Next, the control unit 10 performs the second processing (step S12, the second step): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed with the light I1 having the ability to transmit the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a to 14b. Here, since the lower crack amount F4 is specified as the judgment item H47 in the steps S1 and S10 (setting screen H6), at least the imaging C6 that can obtain the lower crack amount F4 is executed.

[0214] Next, the control unit 10 performs the fifth process (step S13): that is, based on the information indicating the formation state obtained in step S12 (second process), it is determined whether the cracks 14a and 14d have not reached the outer surface (the surface 21a and the back surface 21b). Here, in at least one of the cases where the second end 14ae of the crack 14a is not confirmed in the image obtained by the camera C5 and the crack 14d is confirmed on the back surface 21b in the image obtained by the camera C0, it can be determined that the cracks 14a and 14d have reached the outer surface instead of not reaching it (ST). In addition, in the camera C0, the back surface 21b is photographed by the light I1 (refer to Fig.17 ).

[0215] If the determination result of step S13 indicates that the cracks 14a and 14d have reached the outer surface, that is, have not reached the outer surface (step S13: NO), the process proceeds to step S10 in order to reset the irradiation conditions of step S10.

[0216] On the other hand, when the judgment result of step S13 indicates that the cracks 14a and 14d have not reached the outer surface, that is, when they have not reached (step S13: YES), the control unit 10 performs the following processing (step S14): that is, by controlling the input receiving unit 103, the information indicating the irradiation conditions of the laser L in step S11 (first processing) and the information indicating the formation state obtained in step S12 (second processing) are associated with each other and displayed on the input receiving unit 103. The formation state item displayed in this step S14 is the lower crack amount F4 of the judgment item H47 set in step S10. As described above, the judgment item H47 can be selected.

[0217] Therefore, in step S10, the control unit 10 performs the following processing: that is, by controlling the input receiving unit 103, the input receiving unit 103 displays information for guiding the selection of the formation status item displayed on the input receiving unit 103 in step S14 from among the plurality of formation status items. And, the input receiving unit 103 receives the selection of the formation status item in step S10. Next, in step S14, the control unit 10 controls the input receiving unit 103 to associate the information indicating the formation status item (here, the lower crack amount F4) received by the input receiving unit 103 with the information indicating the irradiation condition of the laser L and displays the information on the input receiving unit 103.

[0218] In the next step, the control unit 10 performs the third process (step S15, the third process): that is, based on the information indicating the formation state obtained in step S12, the control unit 10 determines whether the irradiation conditions of the laser L in step S11 (the first process) are qualified. More specifically, the lower crack amount F4 of the judgment item H47 set in step S10, the target value H48 is 40μm, and the specification is ±5μm. Therefore, when the lower crack amount F4 obtained in step S12 is in the range of 35μm to 45μm, the control unit 10 determines that the irradiation conditions of the laser L in step S11 are qualified.

[0219] Furthermore, as described above, the target value H48 and the specification H49 can be selected. Therefore, in step S10, the control unit 10 performs the seventh process: that is, by controlling the input receiving unit 103, information for guiding the input of the target value H48 and the specification H49 of the formation state is displayed on the input receiving unit 103. Furthermore, the input receiving unit 103 receives the input of the target value H48 and the specification H49 in step S10. Furthermore, in step S15, the control unit 10 compares the formation state (lower crack amount F4) under the irradiation conditions of step S11 with the target value H48 and the specification H49 to determine whether it is acceptable or not.

[0220] Afterwards, when the result of step S15 indicates a qualified result (step S15: YES), the control unit 10 controls the input receiving unit 103 to execute the sixth processing (step S16) of displaying the information H7 indicating the judgment result (the result of the qualified or failed judgment) on the input receiving unit 103, and ends the processing. Fig.37 A diagram showing an input receiving unit in a state where information indicating a judgment result (pass) is displayed. Fig.37 As shown, in the information H7 representing the judgment result, not only the above-mentioned correction item H5, judgment item H47 and wafer thickness H33 are displayed, but also the processing output H72, pass / fail judgment H73, adjustment result H74, internal observation image H75 and chart H76 are displayed.

[0221] The machining output H72 is an item for making the pulse energy D3, which is the correction item H5, variable. That is, here, by making the machining output H72 variable at three points, the pulse energy D3 is made variable at three points. In the adjustment result H74, among the three points of the machining output H72 (pulse energy), the machining output H72 (pulse energy) at which the lower crack amount F4 is the largest (assuming that it is displayed as a peak value) is displayed.

[0222] In addition, as for the pulse energy D3 as an irradiation condition item, it can be made variable by processing output as described above. The processing output 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, for example, for the modified region interval D1, when a plurality of light-converging points of the laser L are formed by the branching of the laser, it can be made variable by controlling the position of the light-converging point in the Z direction using the spatial light modulator 5. Furthermore, when there is only one light-converging point of the laser, the modified region interval D1 can be made variable by adjusting the position of the laser irradiation unit 3 in the Z direction between multiple scans.

[0223] Furthermore, the pulse width D2 can be made variable by switching the settings of the laser irradiation unit 3 (combination of the waveform memory-frequency and the original output), or, when a plurality of light sources 31 are installed, by switching the light sources 31, etc. In addition, as an irradiation condition item, a pulse waveform including the pulse width D2 can be set. In this case, for the pulse waveform, not only the pulse width D2 is variable, but also the waveform (rectangular wave, Gaussian, burst pulse) etc. can be variable.

[0224] Furthermore, the pulse interval D4 can be made variable by the relative speed of the focal point of the laser L (the moving speed of the stage 2) or the frequency of the laser L. Furthermore, the spherical aberration correction level D6 can be made variable by a correction ring lens or a modulation pattern. The astigmatism correction level D7 (or the coma correction level) can be made variable by adjusting the optical system or the modulation pattern. Furthermore, the LBA deviation amount D8 can be made variable by controlling the spatial light modulator 5.

[0225] Continue to refer to Fig.37 In the internal observation image H75, an image (an image obtained in the camera C5) is shown in which the focus F is focused on the second end 14ae (lower crack front end) of each of the three processing outputs H72 (pulse energy D3). In the graph H76, the pulse energy D3 is associated with the lower crack amount F4. That is, here, the control unit 10 controls the input receiving unit 103 to associate the information representing the formation state item (lower crack amount F4) received by the input receiving unit 103 in the formation state with the correction item H5 (pulse energy D3) information in the information representing the irradiation conditions (the associated graph H76) and displays it on the input receiving unit 103.

[0226] In addition, information H77 for guiding the user to select whether to change the calibration item and end the adjustment is displayed in information H7 indicating the determination result. Thus, the user can select whether to set the calibration item (here, pulse energy D3) to the value (acceptable value) displayed in adjustment result H74.

[0227] In the next step, the control unit 10 determines whether to end the pass / fail judgment (step S17). In this step S17, the control unit 10 controls the input receiving unit 103 to display information guiding the selection of "whether to end the pass / fail judgment" on the input receiving unit 103, and when the input receiving unit 103 receives an input to end the pass / fail judgment (step S17: YES), the processing is ended. On the other hand, in this step S17, when the input receiving unit 103 receives an input to re-judge without ending the pass / fail judgment (step S17: NO), the process is transferred to the step S10 described later. This is because, even when the re-judgment result of the control unit 10 is pass, there are also situations such as the following: that is, it is desired to set a good condition that is further away from failure, thereby requiring the pass / fail judgment to continue.

[0228] On the other hand, when the result of process S15 is an unqualified result (process S15: No), the control unit 10 controls the input receiving unit 103 to execute the sixth processing (process S18) of displaying the judgment result indicating unqualified (the result of the qualified or unqualified judgment) on the input receiving unit 103, and transfers to process S10. Fig.38 1 is a diagram showing an input receiving unit in a state where information indicating a judgment result (failure) is displayed. Fig.38 As shown, Fig.37 Compared with the information H7 shown in FIG. 1 , the information H8 indicating the judgment result is different in that the pass / fail judgment H73 displays "failure", the adjustment result H74 displays "unable to adjust", and the content of the chart H76 is different. In addition, the information H8 indicating the judgment result displays information H81 for guiding the user to select whether to perform readjustment. Thus, the user can avoid the situation of transferring to step S10 and repeatedly performing re-judgment as described above, and the processing is terminated.

[0229] In addition, in the first embodiment described above, the lower crack amount 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 items can be selected; as the formation state item, any item that is correlated with the selected irradiation condition item (correction item) (here, it can be used for the pass / fail judgment of the irradiation condition item) can be selected.

[0230] For example, even when any one of the modified region interval D1 to the focusing state D5 is selected as the irradiation condition item (correction item), the upper crack front end position F1 to the total crack amount F5, the meandering amount F8 of the lower crack front end, and the presence or absence of black lines between the modified regions F9 can be selected as the formation state item (with correlation). Furthermore, when the focusing state D5 is selected as the irradiation condition item (correction item), the upper and lower crack front end position deviation width F6 and the presence or absence of marks in the modified region F7 can be further selected as the formation state item. The same applies to other embodiments.

[0231] As described above, in the laser processing device 1 and the laser processing method of the present embodiment, after the semiconductor substrate 21 is irradiated with the laser L to form the modified regions 12a, 12b, etc. (the modified regions 12a, 12b and the cracks 14a to 14d extending from the modified regions 12a, 12b), the semiconductor substrate 21 is photographed by the light I1 that penetrates the semiconductor substrate 21, thereby obtaining the formation state of the modified regions 12a, 12b, etc. (processing result). And, thereafter, the pass or fail judgment of the irradiation condition of the laser L is performed based on the formation state of the modified regions 12a, 12b, etc. Therefore, when the pass or fail judgment of the irradiation condition of the laser L is performed based on the formation state of the modified regions 12a, 12b, etc., it is not necessary to cut the semiconductor substrate 21 or perform cross-sectional observation. Therefore, according to the laser processing device 1 and the laser processing method of the present embodiment, the pass or fail judgment of the irradiation condition of the laser L based on the processing result can be simplified.

[0232] In particular, in the laser processing device 1 and the laser processing method of the above-mentioned embodiment, it is possible to grasp the correlation between the formation state of the modified regions 12a, 12b and the irradiation conditions of the laser L and to judge whether the irradiation conditions are acceptable or not, in a state where the modified regions 12a, 12b and the cracks 14a to 14d are not exposed on the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21. Therefore, compared with a state where the cracks 14a to 14d reach the outer surface, it is less susceptible to external influences (such as vibrations or changes over time). Therefore, it is possible to avoid the situation where the cracks 14a to 14d accidentally progress during transportation and split the semiconductor substrate 21.

[0233] Furthermore, the laser processing apparatus 1 of the present embodiment includes an input receiving unit 103 for displaying information and receiving input. Therefore, information can be presented to the user and input of information from the user can be received.

[0234] Furthermore, in the laser processing device 1 of this embodiment, after the third process, the control unit 10 controls the input receiving unit 103 to execute a fourth process of displaying information indicating the result of the pass / fail judgment on the input receiving unit 103. In this case, the result of the pass / fail judgment can be presented to the user.

[0235] Furthermore, in the laser processing device 1 of the present embodiment, the control unit 10 performs the seventh process: that is, before the third process, the control unit 10 controls the input receiving unit 103 so that the input receiving unit 103 displays information for guiding the input of the target value of the forming state. Furthermore, the input receiving unit 103 receives the input of the target value. Furthermore, in the third process, the control unit 10 compares the forming state under the irradiation condition of the first process with the target value based on the information indicating the forming state obtained in the second process, thereby making a pass / fail judgment. Therefore, it is possible to make a pass / fail judgment on the processing state (target value of the forming state) requested by the user.

[0236] Furthermore, in the laser processing device 1 of the present embodiment, when the result of the pass / fail judgment in the third process is unqualified, or when an input for re-judgment is received based on the result of the pass / fail judgment in the third process, the control unit 10 can calibrate at least one of the multiple irradiation condition items included in the irradiation condition as a correction item, and re-judge the process after re-execution of the first process. That is, the control unit 10 can calibrate at least one of the multiple irradiation condition items included in the irradiation condition as a correction item based on the result of the pass / fail judgment in the third process, and re-judge the process after re-execution of the first process. In this case, the irradiation condition of the laser L can be automatically corrected and re-judged based on the result of the pass / fail judgment.

[0237] Furthermore, in the laser processing device 1 of the present embodiment, the control unit 10 may perform an eighth process, that is, when the result of the pass / fail judgment in the third process is unqualified, or when an input for re-judgment is received based on the result of the pass / fail judgment in the third process, the control unit 10 controls the input receiving unit 103 to calibrate at least one of the plurality of irradiation condition items included in the irradiation condition as a correction item, and displays information for guiding the selection of whether to re-execute the process after the first process on the input receiving unit 103. That is, the control unit 10 performs an eighth process: based on the result of the pass / fail judgment in the third process, the control unit 10 controls the input receiving unit 103 to calibrate at least one of the plurality of irradiation condition items included in the irradiation condition as a correction item, and displays information for guiding the selection of whether to re-execute the process after the first process on the input receiving unit 103. In this case, the input receiving unit 103 receives an input for selecting whether to re-judgment. Furthermore, when the input receiving unit 103 receives a selection for re-judgment, the control unit 10 performs re-judgment. In this case, whether or not to perform correction and re-judgment of the irradiation conditions of the laser light L can be selected based on the result of the pass / fail judgment.

[0238] Furthermore, in the laser processing device 1 of the present embodiment, the control unit 10 controls the input receiving unit 103 to execute the ninth process of displaying information for guiding the selection of the correction item on the input receiving unit 103. Furthermore, the input receiving unit 103 receives the input of the selection of the correction item. Furthermore, the control unit 10 calibrates the correction item received by the input receiving unit 103 and re-judges it. At this time, the irradiation condition includes the pulse width (pulse width D2) of the laser L, the pulse energy (pulse energy D3) of the laser L, the pulse interval (pulse interval D4) of the laser L, and the focusing state (focusing state D5) of the laser L as the irradiation condition items.

[0239] Furthermore, the laser processing device 1 of the present embodiment includes: a spatial light modulator 5 that displays a spherical aberration correction pattern for correcting the spherical aberration of the laser light L; and a condenser lens 33 that condenses the laser light L modulated by the spherical aberration correction pattern in the spatial light modulator 5 onto the semiconductor substrate 21. The condensed state includes the deviation amount (LBA deviation amount D8) of the center of the spherical aberration correction pattern relative to the center of the entrance pupil plane 33a of the condenser lens 33.

[0240] Furthermore, in the first process, when a plurality of modified regions 12a, 12b are formed at different positions in the Z direction intersecting the incident surface (back side 21b) of the laser L of the semiconductor substrate 21, the irradiation conditions include the interval between the modified regions 12a, 12b in the Z direction (modified region interval D1) as an irradiation condition item.

[0241] In this case, the item selected by the user among the irradiation conditions of the laser light L can be corrected and re-judged.

[0242] Furthermore, in the laser processing device 1 of the present embodiment, the control unit 10 performs a tenth process: that is, before the third process, the control unit 10 controls the input receiving unit 103 so that the input receiving unit 103 displays information for guiding the selection of an item for performing pass / fail judgment (i.e., judgment item) from among a plurality of forming state items included in the forming state. Furthermore, the input receiving unit 103 receives input for selecting the judgment item. Furthermore, in the third process, the control unit 10 performs pass / fail judgment based on the information indicating the judgment item in the forming state obtained by the second process.

[0243] Here, the semiconductor substrate 21 includes: a back side 21b which is an incident surface of the laser L, and a surface 21a on the opposite side of the back side 21b. The crack includes: a crack 14d extending from the modified region 12b to the back side 21b side, and a crack 14a extending from the modified region 12a to the surface 21a side. And, the formation state includes as formation state items: the length of the crack 14b in the Z direction (upper crack amount F2); the length of the crack 14a in the Z direction (lower crack amount F4); the total length of the cracks 14a to 14d in the Z direction (total crack amount F5); the position of the first end 14de of the front end of the crack 14d on the back side 21b side in the Z direction (upper crack front end position F1); the position of the second end 14ae of the front end of the crack 14a on the surface 21a side ... second end 14ae of the front end of the crack 14a on the surface 21a side in the Z direction (lower crack amount F4); the total length of the cracks 14a to 14d in the Z direction (total crack amount F5); the position of the first end 14de of the front end of the crack 14d on the back side 21b side in the Z direction front end position (F3); deviation width between the first end 14de and the second end 14ae when viewed from the Z direction (deviation width of the upper and lower crack front end positions F6); presence or absence of marks on the modified regions 12a, 12b (presence or absence of marks on the modified regions F7); meandering amount of the second end 14ae when viewed from the Z direction (meaning amount of meandering of the lower crack front end F8); and presence or absence of a crack front end in the area between the modified regions 12a, 12b arranged in the Z direction (presence or absence of black lines between the modified regions F9).

[0244] Therefore, it is possible to make a pass / fail judgment on the item selected by the user in the formation state of the modified regions 12a, 12b, etc.

[0245] [First reference embodiment of laser processing device]

[0246] Next, a description will be given of a first reference embodiment of the laser processing apparatus 1. Here, an example of an operation of deriving (parameter management) the irradiation conditions of the laser light L will be described. Fig.391 is a flowchart showing the main steps of the method for deriving the irradiation conditions. The following method is a first reference method of the laser processing method. Here, first, the control unit 10 of the laser processing device 1 receives input from the user (step S21). Step S21 is described in more detail.

[0247] like Fig.40 As shown, in the step S21, first, the control unit 10 controls the input receiving unit 103 to display information J1 for guiding the user to select whether to perform parameter management, information J2 for guiding the user to select a variable item, information J3 for guiding the user to select a judgment item, and information J4 for indicating that the selection of the processing condition is automatic. The so-called parameter management is, for example, to derive a pattern of irradiation conditions for an object whose irradiation conditions (parameters) for obtaining a desired forming state are unknown.

[0248] Therefore, in this embodiment, as described later, the semiconductor substrate 21 is irradiated with laser light L along a plurality of lines 15 under different irradiation conditions, thereby forming modified regions 12a, 12b, etc. The variable item represents an irradiation condition item that is different for each line 15 among the irradiation conditions. And, the judgment item is an item for judging (evaluating) the variable item among the formation state items. Here, the processing conditions are various conditions that prevent cracks from reaching the outer surface (ST).

[0249] Next, in step S21, the input receiving unit 103 receives the user's selection of whether to execute parameter management, and the selection of variable items and judgment items. Next, when the user selects to execute parameter management, and the variable items and judgment items are selected, the control unit 10 automatically selects an example of processing conditions, and displays information indicating the selected processing conditions on the input receiving unit 103.

[0250] Fig.41 FIG. 2 is a diagram showing an input receiving unit in a state where an example of selected processing conditions is displayed. Fig.41 As shown, the information J5 indicating the processing conditions is displayed on the input receiving unit 103 to prompt the user. The information J5 indicating the processing conditions includes multiple items. Among the multiple items, the item J51 indicating the execution parameter management, the variable item J52, and the judgment item J53 are items indicating the previous selection results, rather than the items currently accepting the selection from the user (the same applies to the wafer thickness J54).

[0251] On the other hand, the control unit 10 prompts an example of 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: the processing position in the Z direction) J60, and accepts the selection (change) from the user. Fig.32 The focal point number H41 to frequency H45 shown are the same.

[0252] Furthermore, in this example, pulse energy D3 is selected as a variable item. Therefore, pulse energy J61 is displayed as a variable condition. Here, an initial value is displayed as pulse energy J61, and a range of levels 1 to 12 is displayed as a variable range J62. Furthermore, three points are displayed as variable point number J63. This means that the number of lines 15 with different irradiation conditions is 3. These items can currently be selected (changed) by the user.

[0253] In the next step, the following processing is performed (step S22): that is, it is determined whether the irradiation condition set in step S21 is actually a condition that prevents the cracks 14a and 14d from reaching the outer surface, that is, a non-reaching condition (ST condition). Here, as in the above-mentioned step S2, the control unit 10 can determine whether the input condition is a non-reaching condition.

[0254] In the next step, if the result of the judgment in step S22 indicates that the irradiation condition set in step S21 is a result that does not reach the condition (step S22: YES), processing is performed according to the information J5 indicated by the processing condition as described above (step S23). That is, here, the control unit 10 performs the following processing (step S23): that is, the laser light L is irradiated to the semiconductor substrate 21 along the plurality of lines 15, respectively, so that the modified regions 12a, 12b, etc. are formed in the semiconductor substrate 21 in a manner that does not reach the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0255] In particular, in this step S23, the semiconductor substrate 21 is irradiated with laser light L under different irradiation conditions for each of the plurality of lines 15. As an example, here, as indicated by the information J5 indicating the processing conditions, the pulse energy D3 is changed between level 1 and level 12 at three points (three lines 15), and irradiation with laser light L is performed. As a result, modified regions 12a, 12b, etc. having different formation states are formed on each line 15. In addition, when the result of the judgment in step S22 indicates that the irradiation condition is not a result of not reaching the condition (step S22: NO), the process returns to step S21 to set the irradiation condition again.

[0256] Next, the control unit 10 performs the following processing (step S24): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed with the light I1 having the ability to transmit the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a to 14b. In particular, in this step S24, information indicating the formation state is obtained for each of the plurality of lines 15. Here, since the lower crack amount F4 is specified as the judgment item J53 in step S21, at least the imaging C5 and the imaging C6 necessary for obtaining the lower crack amount F4 are performed (other imaging may also be performed).

[0257] Next, the control unit 10 controls the input receiving unit 103 to display information indicating the processing result on the input receiving unit 103 (step S25 ). Fig.42 1 is a diagram showing an input receiving unit in a state where information indicating a processing result is displayed. Fig.42 As shown, in step S25, information J7 indicating the processing result is displayed. The information J7 indicating the processing result displays not only the variable item J52, the judgment item J53, and the wafer thickness J54 described above, but also pulse energy J72, result display J73, internal observation image J74, and graph J75.

[0258] The pulse energy J72 is an item indicating the variable value of the pulse energy of the variable item J52. That is, here, the pulse energy D3 is made different at three points shown in the figure. The internal observation image J74 shows an image (an image obtained by the camera C5) in which the focus F is focused on the second end 14ae (lower crack front end) of each of the three processing outputs (pulse energy D3).

[0259] The relationship between the pulse energy D3 and the lower crack amount F4 is shown in the graph J75. That is, in the step S25, the control unit 10 performs the following processing: that is, by controlling the input receiving unit 103, the information indicating the irradiation conditions of the laser L in the step S23 and the information indicating the formation state obtained in the step S24 are associated with each other (the associated graph J75) and displayed on the input receiving unit 103.

[0260] Furthermore, the information indicating the formation state (formation state item) displayed in the step S25 is the lower crack amount F4 of the judgment item J53 set in the step S21. As described above, the judgment item J53 can be selected. Therefore, in the step S21, the control unit 10 performs the following processing: that is, by controlling the input receiving unit 103, the input receiving unit 103 displays information for guiding the selection of the formation state item displayed on the input receiving unit 103 in the step S25 from among the plurality of formation state items.

[0261] Furthermore, the input receiving unit 103 receives the selection of the formation status item in step S21. Next, in step S25, the control unit 10 controls the input receiving unit 103 to associate the information indicating the formation status item (here, the lower crack amount F4) received by the input receiving unit 103 with the information indicating the irradiation condition of the laser L (here, the pulse energy D3) and displays the information on the input receiving unit 103.

[0262] Similarly, in step S21, the control unit 10 performs the following processing: namely, by controlling the input receiving unit 103, the input receiving unit 103 is caused to display information for guiding the selection of "the irradiation condition item displayed on the input receiving unit 103 in step S25 (which is a variable item that is different for each line 15)" from "a plurality of irradiation condition items included in the irradiation condition of the laser L". Furthermore, the input receiving unit 103 receives the input of the selection of the irradiation condition item (variable item), and the control unit 10 controls the laser irradiation unit 3 so that the variable item (here, the pulse energy D3) received by the input receiving unit 103 is different for each line 15 to perform step S23, and the control unit 10 controls the input receiving unit 103 to associate the information indicating the variable item (here, the pulse energy D3) received by the input receiving unit 103 among the irradiation conditions with the information indicating the formation state (here, the lower crack amount F4) and displays the information on the input receiving unit 103.

[0263] In particular, as shown in the graph J75, the control unit 10 associates and acquires information indicating the irradiation conditions in step S23 (here, the pulse energy D3) and information indicating the formation state (here, the amount of lower crack F4) for each of the plurality of lines 15 by taking the image in step S24. As a result, in the laser processing device 1, for example, the relationship between the irradiation conditions and the formation state can be acquired for an unknown object (parameter management can be performed). In particular, as Fig.43 As shown in the figure, by displaying a graph with a variable item (parameter) as the horizontal axis AX and the formation state under the variable item as the vertical axis AY, parameter management can be performed in a visual manner. Therefore, the user can adjust the irradiation conditions to the irradiation conditions that make the modified areas 12a, 12b, etc. become the required formation state.

[0264] In the next step, the control unit 10 displays information J76 on the input receiving unit 103 to guide the user to select whether to continue parameter management. Fig.42As shown, the information J76 has been displayed in step S25. Therefore, here, the input receiving unit 103 receives the selection of whether to continue parameter management (step S26). The so-called "continue parameter management" means changing the variable item or judgment item and performing reprocessing. In the case where the result of step S26 is a result indicating that reprocessing is not required (step S26: YES), the processing is terminated.

[0265] On the other hand, if the result of step S26 indicates that reprocessing is necessary (step S26: NO), the control unit 10 controls the input receiving unit 103 to display information J2 for guiding the user to select a variable item, information J3 for guiding the user to select a judgment item, information J4 for indicating that the processing condition is selected automatically, and information J5 for indicating the processing condition, and accepts input (step S27). Here, for example, an irradiation condition item different from the variable item selected in step S21 can be set as a variable item, or a formation state item different from the judgment item selected in step S21 can be set as a judgment item.

[0266] Next, the control unit 10 performs processing similar to step S23 (step S28 ) and takes images similar to step S24 (step S29 ) based on the input received in step S27 , thereby acquiring information indicating the formation status of the modified regions 12 a , 12 b , etc.

[0267] Next, the control unit 10 performs the following processing (step S30): that is, based on the information indicating the formation state obtained in step S29, it is determined whether the cracks 14a and 14d have not reached the outer surface. Here, when at least one of the second end 14ae of the crack 14a is not confirmed in the image obtained by the camera C5 and the crack 14d is confirmed on the back surface 21b in the image obtained by the camera C0, it can be determined that the cracks 14a and 14d have reached the outer surface, not that they have not reached.

[0268] If the result of the judgment in step S30 indicates that the cracks 14a and 14d have reached the outer surface, that is, if they have not reached the outer surface (step S30: No), the process proceeds to step S27. On the other hand, if the result of the judgment in step S30 indicates that the cracks 14a and 14d have not reached the outer surface, that is, if they have not reached the outer surface (step S30: Yes), similarly to step S25, the control unit 10 displays information indicating the processing result on the input receiving unit 103 (step S31), and judges whether reprocessing is required (step S32). If the result of step S32 indicates that reprocessing is not required, the process is terminated; if the result of step S32 indicates that reprocessing is required, the process proceeds to step S27.

[0269] [Second reference embodiment of laser processing device]

[0270] Next, the reference method of the laser processing device 1 is described. Here, the irradiation conditions of the laser L are derived in the same manner as the first reference method. However, here, the variable item is set to the LBA deviation D8 included in the focusing state D5 among the irradiation condition items. First, the LBA deviation is described. As described above, the laser irradiation unit 3 has a spatial light modulator 5 and a focusing lens 33 that focuses the laser L modulated by the spatial light modulator 5. And the modulation pattern displayed on the reflection surface 5a of the spatial light modulator 5 is transferred to the incident pupil plane 33a of the focusing lens 33.

[0271] By irradiating the laser L in a state where the center of the modulation pattern is deviated from the center of the entrance pupil plane 33a of the condenser lens 33, the formation state of the modified regions 12a, 12b, etc. is changed. In particular, by deviating the center of at least the spherical aberration correction pattern in the modulation pattern from the center of the entrance pupil plane 33a of the condenser lens 33, the formation state can be properly controlled. The LBA deviation amount D8 is the deviation amount of the center of the spherical aberration correction pattern from the center of the entrance pupil plane 33a of the condenser lens 33. Among the LBA deviation amounts D8, the deviation amount in the X direction is referred to as the X displacement amount, and the deviation amount in the Y direction is referred to as the Y displacement amount. The X direction is the direction of travel of the laser light focal point and is parallel to the direction of travel of the laser processing; the Y direction is the direction orthogonal to the direction of travel of the laser light focal point and is perpendicular to the direction of travel of the laser processing.

[0272] Fig.44 This is a graph showing the relationship between the Y deviation and the forming state. Fig.44In (a), the modified region 12 and the crack 14 extending from the modified region 12 are shown when the Y deviation is changed from -2.0 to +2.0% in units of 0.5. A pair of modified regions 12 (and corresponding cracks 14) are shown for each Y deviation, wherein the left one is when processed on the forward path (X positive direction) and the right one is when processed on the return path (X negative direction). In addition, the Y deviation corresponds to the pixel of the spatial light modulator 5. Fig.44 (b) shows the cut surface after processing with each Y deviation. Fig.44 In the example, the X deviation is constant.

[0273] like Fig.44 As shown, when the modified region 12 and the crack 14 are formed in the semiconductor substrate 21 by irradiating the laser L, if the Y deviation 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, it is possible to derive the irradiation conditions of the laser L that make the modified region 12 and the crack 14 become the required formation state. In addition, the LBA deviation D8 is related to all of the above-mentioned upper crack front end position F1 and the presence or absence of the black line F9 between the modified region in the formation state. The following is a description of the method of deriving the LBA deviation D8 among the irradiation conditions of the laser L.

[0274] Fig.45 and Fig.46 The following is a flow chart showing the main steps of the method for deriving the LBA deviation. The following method is a second reference method for the laser processing method. Fig.45 As shown, here, first, the control unit 10 receives input from the user (step S41). The step S41 is described in more detail. In the step S41, first, by controlling the input receiving unit 103, information (not shown) for guiding the user to select whether to perform the LBA deviation check is displayed on the input receiving unit 103. The so-called LBA deviation check is a check for deriving the LBA deviation amount.

[0275] Next, in step S41, the input receiving unit 103 receives the user's selection of whether to execute the LBA deviation check. Next, in step S41, if the input receiving unit 103 receives the selection of executing the LBA deviation check, Fig.47As shown, the control unit 10 displays information K1 for guiding the user to select the inspection condition on the input receiving unit 103. The information K1 includes a plurality of items. Among the plurality of items, the LBA deviation check K2 is an item for guiding the user to select "whether to check (derive) the X deviation amount, whether to check (derive) the Y deviation amount, or whether to check (derive) both the X deviation amount and the Y deviation amount".

[0276] LBA-X deviation K3 indicates a variable range of X deviation (e.g., ±6), which can be selected by the user (or automatically selected). LBA-Y deviation K4 indicates a variable range of Y deviation (e.g., ±2), which can be selected by the user (or automatically selected). Judgment item K5 indicates a formation state item for deriving LBA deviation, which can be selected by the user (or automatically selected). In addition, wafer thickness K6 can also be selected by the user (or automatically selected).

[0277] Next, in step S41, the input receiving unit 103 receives at least the input of the LBA deviation check K2. Furthermore, when the input receiving unit 103 receives the input of the LBA deviation check K2 (for LBA-X deviation K3, LBA-Y deviation K4, judgment item K5, and wafer thickness K6, automatic selection is performed without input from the user), the control unit 10 controls the input receiving unit 103 to display a setting screen including the selection result on the input receiving unit 103.

[0278] Fig.48 2 is a diagram showing an input receiving unit in a state where a setting screen is displayed. Fig.48 As shown in FIG. 1 , the setting screen K7 includes a plurality of items. Among the plurality of items, LBA deviation check K71, judgment item K72, X deviation variable range K73, Y deviation variable range K74 and wafer thickness K75 are items indicating the previous selection results, rather than items currently accepting selections from the user. In addition, LBA deviation check K71 indicates the selection of Fig.47 In the LBA deviation check K71, both the X deviation amount and the Y deviation amount are checked (derived).

[0279] On the other hand, the number of focus K81, the number of scans K82, the processing speed K83, the pulse width K84, the frequency K85, the ZH (Z height: the processing position in the Z direction) K86, and the processing output K87 are examples of what the control unit 10 presents, and currently accepts selection (change) from the user. In addition, the meanings of the number of focus K81 to the frequency K85 are the same as Fig.34 The focus number H41 to frequency H45 shown in are the same.

[0280] In the next step, the control unit 10 performs the following processing (step S42): that is, it is judged whether the processing conditions (irradiation conditions) set in step S41 are actually conditions that prevent the cracks 14a and 14d from reaching the outer surface (the surface 21a and the back surface 21b), that is, non-reaching conditions (ST conditions). Here, the control unit 10 can judge whether the received input conditions are non-reaching conditions, as in the above-mentioned step S2. If the result of the judgment of step S42 is a result indicating that the basic processing conditions are not non-reaching conditions (step S42: NO), the process is transferred to step S41.

[0281] On the other hand, if the result of the determination in step S42 indicates that the basic processing condition is not reached (step S42: YES), processing is performed according to the selection content and processing conditions displayed on the setting screen K7 (step S43). That is, here, the control unit 10 performs the following processing: namely, the laser light L is irradiated to the semiconductor substrate 21 along the plurality of lines 15, respectively, so that the modified regions 12a, 12b, etc. are formed in the semiconductor substrate 21 in a manner that does not reach the outer surface (the front surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0282] In particular, in step S43, the semiconductor substrate 21 is irradiated with laser light L at different LBA deviations D8 (irradiation conditions, focusing state D5) for each of the plurality of lines 15. As an example, here, the X deviation is set to a constant value, and the Y deviation is changed from -2 to +2 in units of 0.5 as shown in the Y deviation variable range K74, while irradiation with laser light L is performed. As a result, modified regions 12a, 12b, etc. having different formation states are formed on each of the lines 15.

[0283] Next, the control unit 10 performs the following processing (step S44): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed with the light I1 having the ability to transmit the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a to 14b. In particular, in this step S44, information indicating the formation state is obtained for each of the plurality of lines 15. Here, since the lower crack amount F4 is specified as the judgment item K5 (judgment item K72) in step S41, at least the imaging C5 and the imaging C6 necessary for obtaining the lower crack amount F4 are performed (other imaging may also be performed).

[0284] Next, the control unit 10 controls the input receiving unit 103 to display information indicating the processing result on the input receiving unit 103 (step S45 ). Fig.49 1 is a diagram showing an input receiving unit in a state where information indicating a processing result is displayed. Fig.49As shown, in step S45, information K9 indicating the processing result is displayed. The information K9 indicating the processing result displays not only the above-mentioned LBA deviation check K71, judgment item K72, X deviation variable range K73, Y deviation variable range K74, and wafer thickness K75, but also judgment K91, X deviation judgment K92, Y deviation judgment K93, X deviation K95, and Y deviation K96.

[0285] The judgment K91 indicates whether the judgment of the LBA deviation amount of the required formation state (i.e., the derivation of the LBA deviation amount) has been completed. Here, as an example of the LBA deviation amount of the required formation state, the lower crack amount F4 is exemplified as an LBA deviation amount showing a peak value, however, it may not be a peak value and can be set by the user. Here, in the judgment K91, it is displayed that the judgment has been completed, that is, it is displayed that the LBA deviation amount showing a peak value of the lower crack amount F4 is obtained.

[0286] Furthermore, the X deviation value for obtaining the desired formation state (the lower crack amount F4 shows a peak value) is indicated in the X deviation judgment K92, and the Y deviation value for obtaining the desired formation state (the lower crack amount F4 shows a peak value) is indicated in the Y deviation judgment K93. That is, when the peak value of the formation state is obtained, the control unit 10 controls the input receiving unit 103 to display the irradiation condition corresponding to the peak value (here, the LBA deviation amount D8) on the input receiving unit 103. In addition, in the first reference mode described above, when the peak value is obtained, the control unit 10 can also display the irradiation condition corresponding to the peak value on the input receiving unit 103. In addition, even when the peak value of the formation state is obtained, the control unit 10 can display the irradiation condition corresponding to the value shifted from the peak value on the input receiving unit 103. This is to allow a margin for the irradiation condition that can obtain the desired formation state.

[0287] The X deviation K95 includes a graph K951 and a lower crack front end K952 of the internal image, and the Y deviation K96 includes a graph K961 and a lower crack front end K962 of the internal image. In the graph K951, the X deviation amount is associated with the lower crack amount F4 and displayed. In addition, in the graph K961, the Y deviation amount is associated with the lower crack amount F4 and displayed. In addition, in the information K9 indicating the processing result, not only the information on the Y deviation but also the information on the X deviation is displayed for convenience. However, currently, only the processing that makes the Y deviation amount variable is performed, so the information on the X deviation is not displayed.

[0288] As shown in the graph K961, the lower crack amount F4 becomes a peak value when the Y deviation amount is ± 0. Therefore, in the Y deviation judgment K93, ± 0 is displayed as the Y deviation amount that gives the peak value of the lower crack amount F4. And the judgment (derivation) of the Y deviation amount that gives the peak value of the lower crack amount F4 in the judgment K91 is completed.

[0289] Thus, the relationship between the Y deviation amount in the LBA deviation amount D8 and the lower crack amount F4 is shown in the graph K961. That is, in this step S45, the control unit 10 controls the input receiving unit 103 to associate the information indicating the irradiation conditions of the laser L in the step S43 with the information indicating the formation state obtained in the step S44 (the associated graph K961) and displays them on the input receiving unit 103.

[0290] Furthermore, the information indicating the formation state (formation state item) displayed in the step S45 is the lower crack amount F4 of the judgment item K5 (judgment item K72) set in the step S41. As described above, the judgment item K5 can be selected. Therefore, in the step S41, the control unit 10 performs the following processing: that is, 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 the step S45 from among the plurality of formation state items.

[0291] Furthermore, the input receiving unit 103 receives the selection of the formation status item in step S41. Next, in step S45, the control unit 10 controls the input receiving unit 103 to associate the information indicating the formation status item (here, the lower crack amount F4) received by the input receiving unit 103 with the information indicating the irradiation condition of the laser L (here, the LBA deviation amount D8) and displays the information on the input receiving unit 103.

[0292] In the next step, the control unit 10 determines whether the determination (derivation) of the LBA deviation D8 (here, the Y deviation) is completed, that is, whether the LBA deviation showing the peak value of the lower crack amount F4 is obtained (step S46). When the result of the determination of step S46 indicates that the determination of the LBA deviation D8 is completed (step S46: YES), processing is performed according to the selection content and processing conditions displayed on the setting screen K7 (step S47, the first step). That is, here, the control unit 10 performs the following processing: namely, the laser L is irradiated to the semiconductor substrate 21 along the plurality of lines 15, respectively, so that the modified regions 12a, 12b, etc. are formed in the semiconductor substrate 21 in a manner that does not reach the outer surface (the surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0293] In particular, in step S47, the semiconductor substrate 21 is irradiated with laser light L at different LBA deviations D8 (irradiation conditions, focusing states) for each of the plurality of lines 15. Here, the Y deviation is kept constant, and the irradiation with laser light L is performed while the X deviation is changed from -6 to +6 as indicated by the X deviation variable range K73. Thus, modified regions 12a, 12b, etc. having different formation states are formed on the respective lines 15.

[0294] Next, the control unit 10 performs the following processing (step S48): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed with the light I1 having the ability to transmit the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a to 14b. In particular, in this step S48, information indicating the formation state is obtained for each of the plurality of lines 15. Here, since the lower crack amount F4 is specified as the judgment item K5 (judgment item K72) in step S41, at least the imaging C5 and the imaging C6 necessary for obtaining the lower crack amount F4 are performed (other imaging may also be performed).

[0295] Next, the control unit 10 performs the following processing (step S49): and, based on the information indicating the formation state obtained in step S48, it is determined whether the cracks 14a and 14d have not reached the outer surface. Here, when at least one of the second end 14ae of the crack 14a is not confirmed in the image obtained by camera C5 and the crack 14d is confirmed on the back surface 21b in the image obtained by camera C0, it can be determined that the cracks 14a and 14b have reached the outer surface and have not not reached (ST). When the judgment result of step S49 is a result indicating that the cracks 14a and 14d have reached the outer surface, that is, when they have not not reached (step S49: NO), the process moves to step S41.

[0296] On the other hand, when the judgment result of step S49 indicates that the cracks 14a and 14d have not reached the outer surface, that is, when they have not reached the outer surface (step S49: YES), the control unit 10 controls the input receiving unit 103 to display information indicating the processing result on the input receiving unit 103 (step S50). The information displayed here indicates Fig.49 At the time of step S45, since only the processing to make the Y deviation amount variable is performed, the information about the X deviation is not displayed. However, here, the processing to make the X deviation amount variable is also completed, so the information about the X deviation is also displayed (displayed). Fig.49All items). As shown in the graph K951, in the processing of the forward path, the lower crack amount F4 becomes a peak value when the X deviation amount is ±0. And, in the processing of the return path, the lower crack amount F4 becomes the maximum when the X deviation amount is +3. Therefore, in the X deviation judgment K92, as the X deviation amount given to the peak value of the lower crack amount F4, ±0, +3 (X deviation amount given the maximum value) are displayed. And, in the judgment K91, it is displayed that the judgment (derivation) of the X deviation amount given to the peak value of the lower crack amount F4 has been completed.

[0297] The relationship between the X deviation amount in the LBA deviation amount D8 and the lower crack amount F4 is shown in the graph K951. That is, in this step S50, the control unit 10 performs the following processing: that is, by controlling the input receiving unit 103, the information indicating the irradiation conditions of the laser L in the step S47 and the information indicating the formation state obtained in the step S48 are associated with each other (the associated graph K951) and displayed on the input receiving unit 103.

[0298] Furthermore, the information indicating the formation state (formation state item) displayed in the step S50 is the lower crack amount F4 of the judgment item K5 (judgment item K72) set in the step S41. As described above, the judgment item K5 can be selected. Therefore, in the step S41, the control unit 10 performs the following processing: that is, 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 the step S50 from among the plurality of formation state items.

[0299] Furthermore, the input receiving unit 103 receives the selection of the formation status item in step S41. Next, in step S50, the control unit 10 controls the input receiving unit 103 to associate the information indicating the formation status item (here, the lower crack amount F4) received by the input receiving unit 103 with the information indicating the irradiation condition of the laser L (here, the LBA deviation amount D8) and displays the information on the input receiving unit 103.

[0300] In the next step, the control unit 10 determines whether the determination (derivation) of the LBA deviation amount D8 (here, the X deviation amount) has been completed (step S51). If the result of the determination in step S51 is a result indicating that the determination of the LBA deviation amount D8 has been completed (step S51: YES), the processing is terminated. In addition, in the information K9 indicating the processing result, information K97 for guiding the selection of whether to change the value of the LBA deviation amount D8 to the determined value (the value displayed in the X deviation determination K92 and the Y deviation determination K93) is displayed. In addition, when the information K9 is displayed, the user can select whether to change the value of the LBA deviation amount D8 to the determined value.

[0301] In this regard, if the judgment result of step S46 indicates that the judgment of the Y deviation amount is not completed (step S46: No), and if the judgment result of step S51 indicates that the judgment of the X deviation amount is not completed (step S51: No), it is judged that the required forming state (here, the peak value) cannot be obtained by the variable range of the LBA deviation amount D8 and the judgment item previously selected, and the process is transferred to Fig.46 Step S52 is shown.

[0302] That is, in the next step, the control unit 10 expands the variable range of the LBA deviation amount D8 (step S52). When the process is transferred from step S46 to step S52, the variable range of the Y deviation amount in the LBA deviation amount D8 is expanded from the Y deviation variable range K74 (±2); when the process is transferred from step S51 to step S52, the variable range of the X deviation amount in the LBA deviation amount D8 is expanded from the X deviation variable range K73 (±6). In addition, in the following steps, although the determination of the Y deviation amount is described, the same is true for the determination of the X deviation amount.

[0303] In the next step, the following processing (step S53) is performed: that is, it is determined whether the processing conditions (irradiation conditions) corresponding to the variable range expanded in step S52 are conditions that prevent the cracks 14a and 14d from reaching the outer surface, that is, non-reaching conditions. Here, as in the above-mentioned step S2, the control unit 10 can determine whether the conditions corresponding to the expanded variable range are non-reaching conditions. In the case where the result of the determination in step S53 indicates that the basic processing conditions are not non-reaching conditions (step S53: No), the process is transferred to step S52 to adjust the degree of expansion of the variable range.

[0304] On the other hand, if the result of the determination in step S53 indicates that the basic processing condition is not the condition (step S53: YES), processing is performed in the expanded variable range (step S54). That is, here, the control unit 10 performs the following processing: namely, the laser light L is irradiated to the semiconductor substrate 21 along the plurality of lines 15, respectively, so that the modified regions 12a, 12b, etc. are formed in the semiconductor substrate 21 in a manner that does not reach the outer surface (the front surface 21a and the back surface 21b) of the semiconductor substrate 21.

[0305] In particular, in step S54, the semiconductor substrate 21 is irradiated with laser light L at different Y deviations (irradiation conditions, focusing states) for each of the plurality of lines 15. Here, the X deviation is kept constant, and the irradiation with laser light L is performed while the Y deviation is changed within an expanded variable range. Thus, modified regions 12a, 12b, etc. having different formation states are formed on the respective lines 15.

[0306] Next, the control unit 10 performs the following processing (step S55): that is, by controlling the imaging unit 4, the semiconductor substrate 21 is photographed with the light I1 having the ability to transmit the semiconductor substrate 21, thereby obtaining information indicating the formation state of the modified regions 12a, 12b and / or the cracks 14a-14b. Fig.45 Next, the control unit 10 controls the input receiving unit 103 to display information indicating the processing result on the input receiving unit 103 (step S56). This step S56 is the same as step S44 shown in FIG. Fig.45 The same as step S45 shown in .

[0307] Next, the control unit 10 determines whether the determination (derivation) of the LBA deviation amount D8 (here, the Y deviation amount) has been completed, that is, whether the LBA deviation amount D8 showing the peak value of the lower crack amount F4 has been 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 been completed (step S57: NO), the processing is terminated.

[0308] On the other hand, if the result of the determination in step S57 indicates that the determination of the LBA deviation amount D8 has not been completed (step S57: YES), the control unit 10 changes the determination item (step S58). More specifically, in this case, the item used for determining the LBA deviation amount D8 among the status items is set to Fig.47 Items other than the determination item K5 (here, the lower crack amount F4) specified by the information K1 shown in FIG.

[0309] like Fig.50 As shown, when the judgment item is the lower crack front end position F3 ( Fig.50 (a)) and when the upper crack front position is F1 ( Fig.50 (b)), both can obtain a peak value corresponding to the change in Y deviation, and the Y deviation given to the peak value is different from the existing method ( Fig.50 The Y deviation Oc in (c) is consistent. And, Fig.51 As shown, even when the judgment item is the upper and lower crack tip position deviation width F6, the peak value can be obtained by the approximate formula according to the change of the Y deviation amount, and the Y deviation amount given to the peak value is different from the conventional method ( Fig.51 The Y deviation Oc in (c)) is consistent.

[0310] And, if Fig.52 and Fig.53As shown, even when the judgment item is the presence or absence of the modified area mark F7, the change in the appearance of the mark can be observed with the change of the Y deviation, and the clearest mark is confirmed at about Y deviation ±0 (the same Y deviation as other judgment items and the existing method). In this way, in step S58, various judgment items can be used instead of the above-mentioned lower crack amount F4.

[0311] In addition, the judgment of the X deviation is the same. As an example, Fig.54 As shown, even when the judgment item is the lower crack amount F4, a peak value can be obtained corresponding to the change in the X deviation amount, and the X deviation amount given to the peak value is different from the conventional method ( Fig.54 (b) of ±0 (outward) and +2 (return) are consistent. And, if Fig.55 (Outgoing) and Fig.56 As shown in (return path), when the judgment item is the meandering amount F8 of the front end of the lower crack, it can be observed that the meandering amount F8 of the front end of the lower crack changes in accordance with the change of the X deviation amount, and the X deviation amount that makes the meandering amount F8 of the front end of the lower crack the minimum is consistent with the above situation. In this way, various judgment items can also be used for the judgment of the X deviation amount.

[0312] Next, processing (step S59), imaging (step S60), and result display (step S62) are performed. Step S59 is the same as the above-mentioned step S54, step S60 is the same as the above-mentioned step S55, and step S62 is the same as the above-mentioned step S56. However, in step S60, the imaging C1 to C11 is an imaging that can obtain the judgment items changed in step S58.

[0313] Here, after step S60 and before step S62, the control unit 10 performs the following processing (step S61): namely, judging whether the cracks 14a and 14d have not reached the outer surface based on the information indicating the formation state obtained in step S60. Here, in at least one of the cases where the second end 14ae of the crack 14a is not confirmed in the image obtained by camera C5 and the crack 14d is confirmed on the back surface 21b in the image obtained by camera C0, it can be judged that the cracks 14a and 14b have reached the outer surface. If the judgment result of step S61 is a result indicating that the cracks 14a and 14d have reached the outer surface, that is, if they have not reached (step S61: NO), the process proceeds to step S58; and if the judgment result of step S61 is a result indicating that the cracks 14a and 14b have not reached the outer surface, that is, if they have not reached (step S61: YES), the process proceeds to step S62 as described above.

[0314] Next, the control unit 10 determines whether the determination (derivation) of the LBA deviation amount D8 (here, the Y deviation amount) has been completed, that is, whether the LBA deviation amount D8 showing the peak value (required state) has been obtained for the changed determination item (step S63). If the result of the determination in step S63 indicates that the determination of the LBA deviation amount D8 has been completed (step S63: NO), the processing is terminated.

[0315] On the other hand, if the result of the determination in step S63 indicates that the determination of the LBA deviation amount D8 is not completed (step S63: YES), the control unit 10 changes the irradiation conditions other than the above-mentioned irradiation condition items such as enhanced focusing correction (step S64). Then, processing (step S65), imaging (step S66), and result display (step S68) are performed. Step S65 is the same as the above-mentioned step S54, step S66 is the same as the above-mentioned step S55, and step S68 is the same as the above-mentioned step S56.

[0316] However, here, after step S66 and before step S68, the control unit 10 performs the following processing (step S67): based on the information indicating the formation state obtained in step S65, it is determined whether the cracks 14a and 14d have not reached 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 obtained by camera C5 and the case where the crack 14d is confirmed on the back surface 21b in the image obtained by camera C0, it can be determined that the cracks 14a and 14b have reached the outer surface. If the result of the determination in step S67 is a result indicating that the cracks 14a and 14d have reached the outer surface, that is, not not reached (step S67: NO), the process proceeds to step S64; and if the result of the determination in step S67 is a result indicating that the cracks 14a and 14b have not reached the outer surface, that is, not reached (step S67: YES), the process proceeds to step S68 as described above.

[0317] Next, the control unit 10 determines whether the determination (derivation) of the LBA deviation amount D8 (here, the Y deviation amount) has been completed, that is, whether the LBA deviation amount D8 that displays the peak value (required state) is obtained for the changed irradiation conditions (step S69). If the result of the determination in step S69 indicates that the determination of the LBA deviation amount D8 has been completed (step S69: NO), the processing is terminated.

[0318] On the other hand, if the result of the determination in step S69 indicates that the determination of the LBA deviation amount D8 is not completed (step S69: YES), the control unit 10 controls the input receiving unit 103 to display a message notifying the user of an error on the input receiving unit 103 (step S70), and terminates the process. This is because the required forming state cannot be obtained by expanding the variable range of the LBA deviation amount D8, changing the determination item, or changing the irradiation conditions, so there is a possibility that the device state is abnormal.

[0319] [Explanation of Modifications]

[0320] The above embodiment is merely an explanation of one aspect of the present invention. Therefore, the present invention is not limited to the above embodiment, and can be modified arbitrarily.

[0321] For example, in the above-mentioned embodiment, as the processing of the laser processing device 1, an example (cutting example) of cutting the wafer 20 into each functional element 22a along the plurality of lines 15 is cited. However, the laser processing device 1 can also be applied to processing of cutting the object along an imaginary plane of the incident surface of the laser light relative to the object (inside the object) (peeling processing in the thickness direction), or trimming processing of cutting a ring-shaped area including the outer edge of the object from the object, etc.

[0322] Furthermore, in the above-described embodiment, the wafer 20 including the semiconductor substrate 21 which is a silicon substrate is exemplified as the object of the laser processing apparatus 1. However, the object of the laser processing apparatus 1 is not limited to an object including silicon.

[0323] Furthermore, in the above-mentioned embodiments, a part of the irradiation condition items, the formation state items, and the combination thereof are exemplified, however, the irradiation condition items, the formation state items, and the combination thereof are not limited to the irradiation condition items, the formation state items, and the combination thereof exemplified in the above-mentioned embodiments, and any selection can be made. For example, in the first embodiment, the pass / fail judgment of the LBA deviation amount D8 exemplified in the third embodiment can also be performed.

[0324] Furthermore, in the above-described embodiment, when the irradiation conditions of the laser light L are automatically adjusted to the irradiation conditions determined to be acceptable, there is no need to include a step of displaying the information acquired in the second process.

[0325] Furthermore, in the above example, an example of the timing of execution is shown in which "before executing the processing for processing, accepting the setting of the irradiation conditions for the processing, and executing the processing of judging whether the irradiation conditions are non-reaching conditions (fourth processing)" and "executing the processing for processing, and, after executing the processing of obtaining information indicating the formation state, executing the processing of judging whether the cracks 14a, 14d have not reached the outer surface (fifth processing)". However, the timing of execution of these processes is not limited to the above examples and can be arbitrary.

[0326] [Industrial Application Possibility]

[0327] It is possible to provide a laser processing device and a laser processing method that can simplify the pass / fail judgment of laser irradiation conditions based on processing results.

[0328] [Explanation of symbols]

[0329] 1: Laser processing equipment

[0330] 3: Laser irradiation unit (irradiation part)

[0331] 4: Camera unit (camera unit)

[0332] 5: Spatial Light Modulator

[0333] 10: Control Department

[0334] 11: Object

[0335] 21: Semiconductor substrate

[0336] 33: Focusing lens

[0337] 33a: Entrance pupil plane

[0338] 103: Input receiving unit (input unit, display unit).

Claims

1. A laser processing device, wherein: have: an irradiation unit for irradiating a laser beam to an object; an imaging unit for imaging the object; and a control unit that controls at least the irradiation unit and the imaging unit, The control unit performs the following processing: A first process is to irradiate the object with the laser light by controlling the irradiation unit so as to form a modified point and a crack extending from the modified point in the object in a manner that the laser light does not reach an outer surface of the object including a first surface, which is an incident surface of the laser light, and a second surface on the opposite side of the first surface; a second process, after the first process, controlling the imaging unit to image the object with light having a transmittance to the object, thereby acquiring information indicating a formation state of the modified point and / or the crack; as well as A third process is to judge whether the irradiation condition of the laser in the first process is qualified or not based on the information indicating the formation state obtained by the second process after the second process. In the second process, at least the following imaging is performed: The object is imaged by focusing the transmissive light from the second surface side on the front end of the second surface side of the lower fissure in such a manner that the transmissive light focuses on the front end of the virtual image of the lower fissure; as well as, The object is imaged by focusing the focus of the transmissive light on the front end of the virtual image of the modified point on the second surface side from the second surface side, in, The lower crack is the crack extending from the modified point on the second surface side to the second surface side, The virtual image of the lower crack is an image of a position where the lower crack is symmetrical with respect to the second surface. The virtual image of the modified point is an image of a position of the modified point that is symmetrical with respect to the second surface.

2. The laser processing device according to claim 1, wherein: The control unit performs: A fourth process, before the first process, is to determine whether the irradiation condition is a non-reaching condition, wherein the non-reaching condition is a condition that the cracks do not reach the outer surface. If the result of determination in the fourth process is that the irradiation condition is the non-reaching condition, the first process is executed.

3. The laser processing device according to claim 1, wherein: The control unit performs: a fifth process, after the second process and before the third process, judging whether the crack has not reached the outer surface based on the information indicating the formation state obtained by the second process, When the judgment result of the fifth process is that the modified point and the crack have not reached the outer surface, the third process is performed.

4. The laser processing device according to claim 2, wherein: The control unit performs: a fifth process, after the second process and before the third process, judging whether the crack has not reached the outer surface based on the information indicating the formation state obtained by the second process, When the judgment result of the fifth process is that the modified point and the crack have not reached the outer surface, the third process is performed.

5. The laser processing device according to any one of claims 1 to 4, wherein: have: A display unit for displaying information; and The input unit is used to receive input.

6. The laser processing device according to claim 5, wherein: The control unit performs: The sixth process is to display information indicating the result of the pass / fail determination on the display unit by controlling the display unit after the third process.

7. The laser processing device according to claim 5, wherein: The control unit performs: a seventh process of, before the third process, controlling the display unit to display information for guiding input of the target value of the formation state on the display unit, The input unit receives an input of the target value. In the third process, the control unit compares the formation state under the irradiation conditions in the first process with the target value based on the information indicating the formation state acquired in the second process, thereby making the pass / fail determination.

8. The laser processing device according to claim 5, wherein: The control unit calibrates at least one of a plurality of irradiation condition items included in the irradiation conditions as a correction item based on a result of the pass / fail judgment in the third process, and performs a re-judgment of a process after re-executing the first process.

9. The laser processing device according to claim 5, wherein: The control unit executes: an eighth process, according to the result of the pass / fail judgment in the third process, by controlling the display unit, calibrating at least one of the plurality of irradiation condition items included in the irradiation conditions as a correction item, and displaying on the display unit information for guiding the selection of whether to re-execute the process after the first process, The input unit receives an input of a selection of whether to perform the re-judgment, When the input unit receives a selection to perform the re-determination, the control unit performs the re-determination.

10. The laser processing device according to claim 9, wherein: The control unit performs: a ninth process of displaying information for guiding the selection of the correction item on the display unit by controlling the display unit, The input unit receives an input of a selection of the calibration item. The control unit corrects the correction item received by the input unit and performs the re-determination.

11. The laser processing device according to claim 8, wherein: The irradiation condition includes at least one of the following items as the irradiation condition item: The pulse waveform of the laser; The pulse energy of the laser; The pulse spacing of the laser; the focusing state of the laser; and In the first process, when a plurality of modified spots are formed at positions different from each other in a direction intersecting a surface of incidence of the laser light on the object, the interval between the modified spots in the direction intersecting the surface of incidence.

12. The laser processing device according to claim 9, wherein: The irradiation condition includes at least one of the following items as the irradiation condition item: The pulse waveform of the laser; The pulse energy of the laser; The pulse spacing of the laser; the focusing state of the laser; and In the first process, when a plurality of modified spots are formed at positions different from each other in a direction intersecting a surface of incidence of the laser light on the object, the interval between the modified spots in the direction intersecting the surface of incidence.

13. The laser processing device according to claim 10, wherein: The irradiation condition includes at least one of the following items as the irradiation condition item: The pulse waveform of the laser; The pulse energy of the laser; The pulse spacing of the laser; the focusing state of the laser; and In the first process, when a plurality of modified spots are formed at positions different from each other in a direction intersecting a surface of incidence of the laser light on the object, the interval between the modified spots in the direction intersecting the surface of incidence.

14. The laser processing device according to claim 11, wherein: have: a spatial light modulator displaying a spherical aberration correction pattern for correcting the spherical aberration of the laser light; and a condenser lens for condensing the laser light modulated by the spherical aberration correction pattern in the spatial light modulator onto the object, The condensing state includes the amount of deviation of the center of the spherical aberration correction pattern relative to the center of the pupil plane of the condensing lens.

15. The laser processing device according to claim 12, wherein: have: a spatial light modulator displaying a spherical aberration correction pattern for correcting the spherical aberration of the laser light; and a condenser lens for condensing the laser light modulated by the spherical aberration correction pattern in the spatial light modulator onto the object, The condensing state includes the amount of deviation of the center of the spherical aberration correction pattern relative to the center of the pupil plane of the condensing lens.

16. The laser processing device according to claim 13, wherein: have: a spatial light modulator displaying a spherical aberration correction pattern for correcting the spherical aberration of the laser light; and a condenser lens for condensing the laser light modulated by the spherical aberration correction pattern in the spatial light modulator onto the object, The condensing state includes the amount of deviation of the center of the spherical aberration correction pattern relative to the center of the pupil plane of the condensing lens.

17. The laser processing device according to claim 5, wherein: The control unit performs: a tenth process, before the third process, by controlling the display unit, so that the display unit displays information for guiding the selection of an item for the pass / fail judgment, i.e., a judgment item, from among a plurality of forming state items included in the forming state, The input unit receives an input of a selection of the judgment item, In the third process, the control unit performs the pass / fail determination based on the information indicating the determination item in the formation state acquired in the second process.

18. The laser processing device according to claim 17, wherein: The cracks include: a first crack extending from the modified point toward the first surface side, and a second crack extending from the modified point toward the second surface side, The formation status includes at least one of the following items as the formation status 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; The total length of the cracks in the first direction; a position of a first end, the first end being a front end of the first crack on the first surface side in the first direction; a position of a second end, the second end being a front end of the second crack on the second surface side in the first direction; a 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 points; an amount of snaking of the second end when viewed from the first direction; as well as In the first treatment, when a plurality of modified spots are formed at positions different from each other in a direction intersecting the first surface, whether or not there is a front end of the crack in a region between the modified spots arranged in the direction intersecting the first surface.

19. A laser processing method, wherein: The following processes are available: A first step is to irradiate a target object with a laser beam so as not to reach an outer surface of the target object including a first surface, which is an incident surface of the laser beam, and a second surface, which is opposite to the first surface, thereby forming a modified point and a crack extending from the modified point in the target object; a second step of, after the first step, photographing the object using light that is transmissive to the object, thereby acquiring information indicating a formation state of the modified point and / or the crack; as well as A third step is to judge whether the irradiation conditions of the laser in the first step are qualified or not based on the information indicating the formation state obtained in the second step after the second step. In the second step, at least the following video recording is performed: The object is imaged by focusing the transmissive light from the second surface side on the front end of the second surface side of the lower fissure in such a manner that the transmissive light focuses on the front end of the virtual image of the lower fissure; as well as, The object is imaged by focusing the focus of the transmissive light on the front end of the virtual image of the modified point on the second surface side from the second surface side, in, The lower crack is the crack extending from the modified point on the second surface side to the second surface side, The virtual image of the lower crack is an image of a position where the lower crack is symmetrical with respect to the second surface. The virtual image of the modified point is an image of a position of the modified point that is symmetrical with respect to the second surface.

Images