Laser processing method and laser processing apparatus

Abstract

To provide a laser beam machining method and a laser beam machining apparatus capable of suppressing deterioration of machining quality.SOLUTION: The laser processing method includes a step S103 of forming the concave portion CV in the sample A by scanning the sample A with the laser beam L over the first scanning range D2 along the second direction D3 and the third direction R1, and a step S105 of scanning the sample A with the laser beam L over the second scanning range D3 along the second direction D2 and the third direction R2 after the step S103. The second scanning range R2 includes at least a part of the first scanning range D1 when viewed from the first direction R1, and reaches the outside of the first scanning range D2 at least in the second direction R1. In the step S105, the sample A is scanned with the laser beam L over the second scanning range R2 to enlarge the concave portion CV in the first direction D1 and the second direction D2.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a laser processing method and a laser processing apparatus. [Background technology]

[0002] Patent Document 1 describes sample processing using an ion beam. In this method, an A-mode ion beam is used to scan a rectangular hole in the sample, and then a B-mode ion beam is used to scan the cross-section of the sample to create a steeper cross-section. This is followed by a C-mode ion beam for finishing processing to form the cross-section to be observed. The three beam modes, A, B, and C, are characterized by their beam diameter and current. A-mode has a beam diameter of approximately 1 μm and a current of approximately 10 nA; B-mode has a beam diameter of approximately 200 nm and a current of approximately 3 nA; and C-mode has a beam diameter of approximately 30 nm and a current of approximately 200 pA. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-239060 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the area of ​​an observation target has become larger, and there is a demand for processing a large area. However, processing a sample using an ion beam as described in Patent Document 1 is not suitable for processing a large area. In contrast, laser processing is thought to enable processing a sample over a large area at high speed.

[0005] Therefore, the present inventors have studied laser processing of samples and have found the following: When deep processing of a sample is performed using laser light, the number of scans of the laser light (or the number of sets when multiple scans are considered as one set) is increased or the pulse fluence of the laser light is increased based on specific conditions, but increasing the pulse fluence may result in a deterioration of processing quality (quality of the processed cross section). Therefore, in order to maintain processing quality, the number of scans of the laser light is increased unless the pulse fluence is increased.

[0006] However, in this case, as the processing progresses (the processing area deepens), the processing cross section becomes more inclined with respect to the optical axis of the laser light, which may increase the reflectivity of the laser light at the processing cross section or increase the beam area of ​​the laser light at the processing cross section, making it difficult to progress the processing.If the laser light is continuously scanned over the same range in such a state where processing is difficult to progress, the energy of the laser light will accumulate in the sample as heat, which may result in a deterioration of the processing quality.

[0007] Therefore, an object of the present invention is to provide a laser processing method and a laser processing apparatus that can suppress deterioration of processing quality. [Means for solving the problem]

[0008] The laser processing method of the present invention is [1] "a laser processing method for forming a recess in an object by irradiating it with laser light, comprising: a first step of forming the recess in the object by scanning the laser light on the object over a first scanning range along a second direction intersecting a first direction along an optical axis of the laser light and a third direction intersecting the first and second directions; and a second step of scanning the object with the laser light over a second scanning range along the second and third directions after the first step, wherein the second scanning range includes at least a portion of the first scanning range when viewed from the first direction and extends outside the first scanning range in at least the second direction; and in the second step, the recess is enlarged in the first and second directions by scanning the object with the laser light over the second scanning range."

[0009] In this laser processing method, a first step is performed in which a recess is formed in an object by scanning the object with a laser beam over a first scanning range along a second direction intersecting a first direction along the optical axis of the laser beam and a third direction intersecting the first and second directions. Then, a second step is performed in which the object is scanned with the laser beam over a second scanning range along the second and third directions. This expands the recess in the first direction and at least the second direction. The second scanning range, when viewed from the first direction, includes at least a portion of the first scanning range and extends outside the first scanning range in at least the second direction. Thus, in the second step, the laser beam is scanned across at least one outer edge in the second direction of the recess formed in the first step according to the first scanning range (i.e., at least one processed cross section in the first step), thereby forming a new processed cross section. As a result, the energy of the laser beam is newly used for processing (i.e., accumulation of the energy as heat is avoided), making it possible to obtain a high-quality processed cross section with reduced thermal effects. In this way, according to this laser processing method, it is possible to suppress deterioration of processing quality.

[0010] The laser processing method according to the present invention may be [2] "the laser processing method according to the above [1], which includes a third step of moving the position of the focal point of the laser light in the first direction toward the bottom surface of the recess after the first step and before the second step, and in the second step, scanning with the laser light is performed in a state where the focal point is aligned with the position moved in the third step." In this case, it is possible to enlarge the recess in the first direction more efficiently.

[0011] The laser processing method according to the present invention may be [3] "the laser processing method according to the above [1] or [2], further comprising a fourth step of observing, after the second step, the inner surface of the recess facing the second direction with a microscope." In this case, a processed cross section of good quality can be observed.

[0012] The laser processing method according to the present invention may be [4] "the laser processing method according to any one of the above [1] to [3], wherein the recess is formed so that the inner surface of the recess facing the second direction is inclined with respect to the first direction." In this way, the inner surface (processed cross section) of the recess facing the second direction may be inclined with respect to the first direction.

[0013] The laser processing method according to the present invention may be [5] "the laser processing method according to any one of the above [1] to [4], wherein the second scanning range, when viewed from the first direction, extends outside the first scanning range in the second direction and the third direction." In this case, deterioration of the quality of the processed cross section facing the second direction and the processed cross section facing the third direction is suppressed.

[0014] The laser processing method according to the present invention may be [6] "the laser processing method according to any one of the above [1] to [4], wherein the second scanning range, when viewed from the first direction, extends outside the first scanning range only on one side of the second direction." In this case, deterioration of the quality of one processed cross section facing the second direction is suppressed. In other words, it is possible to guarantee the minimum quality of the processed cross section available for observation.

[0015] The laser processing method according to the present invention may be [7] "the laser processing method according to any one of the above [1] to [6], wherein the length of a portion of the second scanning range located outside the first scanning range in the second direction is shorter than the length from one end to the other end in the first direction of an inner surface of the recess formed in the first step, the inner surface facing the second direction." In this case, the generation of a step in the processed cross section of the recess facing the second direction is suppressed.

[0016] The laser processing method according to the present invention may be [8] "the laser processing method according to any one of the above [1] to [7], wherein in the first step, the laser light is scanned a plurality of times over the first scanning range." In this way, by scanning the laser light a plurality of times over the first scanning range, it is possible to form a recess that is deeper in the first direction.

[0017] The laser processing method according to the present invention may be [9] "the laser processing method described in [8] above, in which in the second step, the laser light is scanned multiple times over the second scanning range, and the number of times the laser light is scanned in the first step and the number of times the laser light is scanned in the second step are the same."

[0018] Alternatively, the laser processing method of the present invention may be

[10] "the laser processing method described in [8] above, in which in the second step, the laser light is scanned multiple times over the second scanning range, and the number of times the laser light is scanned in the first step and the number of times the laser light is scanned in the second step are different from each other."

[0019] In this way, by scanning the second scanning range with the laser light multiple times, a recess that is deeper in the first direction can be formed. In this case, the number of times the first scanning range is scanned with the laser light and the number of times the second scanning range is scanned with the laser light may be the same or different. In other words, the number of times the first scanning range is scanned with the laser light and the number of times the second scanning range is scanned with the laser light can be appropriately set according to the requirements of the processed cross section.

[0020] The laser processing method according to the present invention may be

[11] "the laser processing method according to any one of the above [1] to

[10] , wherein the area of ​​the first scanning range is larger than the area of ​​the second scanning range."

[0021] Alternatively, the laser processing method according to the present invention may be

[12] "the laser processing method according to any one of the above [1] to

[10] , wherein the area of ​​the first scanning range is the same as the area of ​​the second scanning range."

[0022] Furthermore, the laser processing method according to the present invention may be

[13] "the laser processing method according to any one of the above [1] to

[10] , wherein the area of ​​the first scanning range is smaller than the area of ​​the second scanning range."

[0023] In this way, the relationship between the area of ​​the first scanning range and the area of ​​the second scanning range can be appropriately set according to the requirements of the shape of the recess.

[0024] The laser processing method according to the present invention may be

[14] "the laser processing method according to any one of the above [1] to

[13] , wherein the pulse width of the laser light is 1 ps or less." In this case, the object is processed by ablation processing, so that it is possible to obtain a processed cross section of good quality with thermal effects further suppressed.

[0025] The laser processing method according to the present invention may be

[15] "the laser processing method according to any one of the above [1] to

[14] , wherein in the second step, the expanded length of the recess in the first direction is greater than the expanded length of the recess in the second direction." In this case, it is possible to form a deeper recess in the first direction while suppressing deterioration in the quality of the processed cross section.

[0026] The laser processing method according to the present invention may be

[16] "the laser processing method according to any one of the above [1] to

[15] , wherein the magnitude of the irradiation energy of the laser light in the first step is the same as the magnitude of the irradiation energy of the laser light in the second step." In this case, there is no need to change the energy of the laser light between the first step and the second step, which makes control easier.

[0027] The laser processing method according to the present invention may be

[17] "the laser processing method according to any one of [1] to [1]5 above, wherein the magnitude of the irradiation energy of the laser light in the first step is greater than the magnitude of the irradiation energy of the laser light in the second step." In this case, the takt time can be shortened.

[0028] The laser processing method according to the present invention may be

[18] "the laser processing method according to any one of the above [1] to

[17] , wherein the laser light modulated by a spatial light modulator is scanned onto the object." In this way, processing may be performed using laser light modulated by a spatial light modulator.

[0029] The laser processing method according to the present invention may be

[19] "the laser processing method according to any one of [1] to

[18] above, further comprising, after the second step, one or more fifth steps of scanning the object with the laser light over a third scanning range along the second direction and the third direction, the third scanning range including at least a part of the second scanning range when viewed from the first direction and extending outside the second scanning range at least in the second direction, and in the fifth step, enlarging the recess in the first direction and the second direction by scanning the object with the laser light over the third scanning range." In this case, it is possible to form a recess that is deeper in the first direction while suppressing deterioration in the quality of the processed cross section.

[0030] The laser processing method according to the present invention may be

[20] "the laser processing method according to the above

[19] , wherein, when the fifth step is performed multiple times, the multiple fifth steps are performed so that the third scanning range in one of the fifth steps includes at least a part of the third scanning range in another fifth step that precedes the first fifth step when viewed from the first direction, and extends outside the third scanning range in the another fifth step at least in the second direction." In this case, it is possible to form a recess that is deeper in the first direction while reliably suppressing deterioration in the quality of the processed cross section.

[0031] The laser processing method according to the present invention may be

[21] "the laser processing method according to the above

[19] or

[20] , which includes a sixth step of moving the position of the focal point of the laser light in the first direction toward the bottom surface of the recess after the second step and before the fifth step, and in the fifth step, scanning with the laser light is performed in a state where the focal point is aligned with the position moved in the sixth step." In this case, it is possible to enlarge the recess in the first direction more efficiently.

[0032] The laser processing device according to the present invention is

[22] "a laser processing device for forming a recess in an object by irradiating it with laser light, comprising: a placement unit on which the object is placed; a laser unit including a laser output unit that outputs the laser light and a laser irradiation unit that irradiates the object placed in the placement unit with the laser light output from the laser output unit; and a control unit that controls the laser unit, wherein the laser irradiation unit has a scanning unit that scans the object placed in the placement unit with the laser light output from the laser output unit, and the control unit scans the object over a first scanning range along a second direction that intersects with a first direction along an optical axis of the laser light, and a third direction that intersects with the first direction and the second direction. a first process for controlling the laser unit to scan the object with the laser light to form the recess in the object; and a second process for controlling the laser unit to scan the object with the laser light over a second scanning range along the second direction and the third direction after the first process, wherein the second scanning range includes at least a portion of the first scanning range when viewed from the first direction and extends outside the first scanning range at least in the second direction, and the control unit controls the laser unit to enlarge the recess in the first direction and the second direction by scanning the object with the laser light over the second scanning range.

[0033] This laser processing device first performs a first process of forming a recess in the object by scanning the object with a laser beam over a first scanning range along a second direction intersecting a first direction along the optical axis of the laser beam and a third direction intersecting the first and second directions. Then, a second process is performed of scanning the object with the laser beam over a second scanning range along the second and third directions. This expands the recess in the first and second directions. The second scanning range, when viewed from the first direction, includes at least a portion of the first scanning range and extends outside the first scanning range in at least the second direction. This allows the second process to scan the laser beam across at least one outer edge in the second direction of the recess formed in the first process according to the first scanning range (i.e., at least one processed cross section in the first step), thereby forming a new processed cross section. As a result, the energy of the laser beam is newly used for processing (i.e., accumulation of the energy as heat is avoided), making it possible to obtain a high-quality processed cross section with reduced thermal effects. In this way, this laser processing device can suppress deterioration of processing quality.

[0034] The laser processing device according to the present invention may be

[23] "the laser processing device according to the above

[22] , wherein the laser irradiation unit includes a spatial light modulator for modulating and emitting the laser light output from the laser output unit, and the scanning unit scans the laser light output from the spatial light modulator over the object placed in the placement unit." In this way, processing may be performed using the laser light modulated by the spatial light modulator.

[0035] The laser processing apparatus according to the present invention is

[24] "a laser processing apparatus comprising: a placement section on which an object is placed; a laser section including a laser output section that outputs laser light and a laser irradiation section for irradiating the object placed in the placement section with the laser light output from the laser output section; and a control section that controls the laser section, wherein the laser irradiation section has a spatial light modulator that modulates and emits the laser light output from the laser output section; and a scanning section that scans the object placed in the placement section with the laser light emitted from the spatial light modulator, and the control section receives input and includes: a setting section that sets irradiation conditions including a scanning range of the laser light, the number of scans to scan the laser light over the scanning range, and the position of the focal point of the laser light; and a laser control section that controls the laser section to scan the object with the laser light under the irradiation conditions set by the setting section."

[0036] In this laser processing device, the control unit receives input from, for example, a user to set irradiation conditions, including the scanning range of the laser beam, the number of scans to be performed over the scanning range, and the position of the focal point of the laser beam, and then scans the target object with the laser beam under these irradiation conditions. This makes it possible to obtain a high-quality processed cross section. In this way, this laser processing device can prevent deterioration of processing quality.

[0037] The laser processing device according to the present invention may be

[25] "the laser processing device according to the above

[24] , wherein the setting unit has a function of setting a scan set for performing a plurality of scans of the laser light while keeping the irradiation conditions constant." In this case, processing is possible in which a plurality of scans of the laser light under constant irradiation conditions are treated as one scan set.

[0038] The laser processing apparatus according to the present invention may be

[26] "the laser processing apparatus described in

[25] above, wherein the setting unit has a function of setting a plurality of the scanning sets, and the laser control unit has a function of controlling the laser unit so as to execute the plurality of scanning sets consecutively when the plurality of scanning sets are set in the setting unit." In this case, consecutive processing using a plurality of scanning sets can be easily performed.

[0039] The laser processing device according to the present invention may be

[27] "the laser processing device according to the above

[26] , in which the number of the scanning sets that can be set by the setting unit is 3 or more." In this case, it becomes possible to easily perform continuous processing using a larger number of scanning sets.

[0040] The laser processing device according to the present invention may be

[28] "the laser processing device described in

[27] above, wherein the setting unit acquires the irradiation conditions for the scanning set between the first scanning set and the last scanning set based on the irradiation conditions for the first scanning set and the irradiation conditions for the last scanning set that are set by accepting input." In this case, for example, it is possible to acquire irradiation conditions for obtaining a good quality processed cross section in an intermediate scanning set based on the irradiation conditions for the first scanning set and the irradiation conditions for the last scanning set that are set by user input.

[0041] The laser processing device according to the present invention may be

[29] "the laser processing device according to any one of the above

[26] to

[28] , wherein, when forming a recess in the object by irradiating the laser light, the setting unit acquires the number of scanning sets and the irradiation conditions for each of the scanning sets based on the opening shape of the target recess." In this case, it is possible to acquire the number of scanning sets and the irradiation conditions for each scanning set for obtaining a processing cross section of good quality based on the opening shape of the target recess. [Effects of the Invention]

[0042] According to the present invention, it is possible to provide a laser processing method and a laser processing apparatus that can suppress deterioration of processing quality. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 is a schematic diagram showing a part of a microscope apparatus according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the remainder of the microscope apparatus shown in FIG. [Figure 3] FIG. 3 is a perspective view showing an example of processing of a sample by the laser processing apparatus shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating a functional configuration of the control unit shown in FIG. [Figure 5] FIG. 5 is a flowchart showing one step of the laser processing method according to this embodiment. [Figure 6] FIG. 6 is a plan view from a first direction showing a scanning range set on a sample. [Figure 7] FIG. 7 is a diagram showing one step of the laser processing method shown in FIG. [Figure 8] FIG. 8 is a diagram showing one step of the laser processing method shown in FIG. [Figure 9] FIG. 9 is a diagram showing one step of the laser processing method shown in FIG. [Figure 10] FIG. 10 is a diagram showing one step of the laser processing method shown in FIG. [Figure 11] FIG. 11 is an SEM image showing the observation result of a processed cross section formed by the laser processing method and laser processing apparatus according to this embodiment. [Figure 12] FIG. 12 is a plan view from a first direction for explaining a scanning range according to the first modified example. [Figure 13] FIG. 13 is a cross-sectional view showing the progress of processing according to the first modified example. [Figure 14] FIG. 14 is a plan view from the first direction for explaining the scanning range according to the second modified example. [Figure 15]FIG. 15 is a cross-sectional view showing the progress of processing according to the second modified example. [Figure 16] FIG. 16 is a cross-sectional view showing the progress of processing according to the third modified example. [Figure 17] FIG. 17 is a cross-sectional view showing the progress of processing according to the fourth modified example. [Figure 18] FIG. 18 is an SEM image showing the processing results when a plurality of scan sets are performed in a state where the enlarged pitch EP is narrower than the reference pitch as shown in FIG. 17(c). [Figure 19] FIG. 19 is a graph showing the measurement results of the displacement of the recess surface (that is, a diagram showing the cross-sectional shape of the recess). [Figure 20] FIG. 20 is an SEM image showing a processed cross section when the pulse energy is set to 1.5 μJ and the enlarged pitch is set to 3.5 μm. [Figure 21] FIG. 21 is an SEM image showing the processed cross section when the pulse energy is increased to 2.0 μJ and the enlarged pitch is maintained at 3.5 μm. [Figure 22] FIG. 22 is an SEM image showing a processed cross section when the pulse energy is increased to 2.0 μJ and the enlarged pitch is increased to 6.0 μm. [Figure 23] FIG. 23 is a cross-sectional view showing the progress of processing according to the fifth modified example. [Figure 24] FIG. 24 is a cross-sectional view showing the progress of processing according to the fifth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0044] A microscope apparatus including a laser processing apparatus according to one embodiment will be described below with reference to the drawings. In the description of the drawings, identical or corresponding elements are given the same reference numerals, and redundant description may be omitted. Each drawing may also depict an orthogonal coordinate system consisting of a first axis defining a first direction D1, a second axis defining a second direction D2 intersecting the first direction D1, and a third axis defining a third direction D3 intersecting the first direction D1 and the second direction D2.

[0045] Fig. 1 is a schematic diagram showing a part of a microscope apparatus according to this embodiment. Fig. 2 is a schematic diagram showing the remaining part of the microscope apparatus shown in Fig. 1. As will be described later, the microscope apparatus 1 shown in Fig. 1 and Fig. 2 includes a focused ion beam (FIB) apparatus that irradiates a sample with focused ions (e.g., Ga ions) to etch the sample, a scanning electron microscope (SEM) apparatus that irradiates the sample with an electron beam to observe the sample, and a laser processing apparatus that irradiates the sample with laser light to perform laser processing (e.g., ablation processing) of the sample, and is an apparatus that allows the SEM apparatus to observe the processed cross section of the sample formed by processing using the FIB apparatus and / or the laser processing apparatus.

[0046] The microscope device 1 includes a sample holder (placement unit) 2, a beam irradiation unit 3, a first microscope unit 4, a second microscope unit 5, a cover 7, a chamber 10, and a laser processing device 20. A sample A is placed on the sample holder 2. The sample holder 2 may support the sample A without fixing it, as in the case where the sample A is simply placed on it, or may hold the sample A fixedly by, for example, gluing it on something. Here, the sample holder 2 holds the sample A. The beam irradiation unit 3 is for irradiating the sample A held (placed (the same applies below)) on the sample holder 2 with a focused ion beam. Therefore, the beam irradiation unit 3 may include at least a focused ion beam emission unit of the FIB device.

[0047] The first microscope unit 4 is for observing the sample A held in the sample holder 2. More specifically, the first microscope unit 4 is configured to be able to obtain an image of the sample A (observe the sample A) by irradiating the sample A held in the sample holder 2 with an electron beam and detecting secondary electrons and the like generated in the sample A. Therefore, the first microscope unit 4 can be at least a part of the SEM device that includes an electron beam emission unit and detection unit.

[0048] Like the first microscope unit 4, the second microscope unit 5 is used to observe the sample A held in the sample holder 2. More specifically, the second microscope unit 5 is capable of irradiating the sample A held in the sample holder 2 with an electron beam and detecting the electron beam scattered by the sample A, thereby acquiring information about the crystalline structure of the sample A (observing the sample A). That is, an example of the second microscope unit 5 may be a part of an SEM device that uses the electron backscatter diffraction (EBSD) method, including at least an electron beam emission unit and a detection unit. Note that the microscope device 1 may be equipped with a transmission electron microscope (TEM) device instead of (or in addition to) the SEM device. In this case, the first microscope unit 4 and the second microscope unit 5 may be at least a part of the TEM device.

[0049] The cover 7 is made of a material that transmits the laser light L described below, and is provided so as to cover the sample A held in the sample holder 2. As a result, the cover 7 can be placed at a reference position that is between the sample holder 2 and the beam irradiation unit 3, the first microscope unit 4, and the second microscope unit 5, and that is interposed in the optical path of the laser light L. The cover 7 is configured to be movable from the reference position so as not to be interposed between the sample holder 2 and the beam irradiation unit 3, the first microscope unit 4, and the second microscope unit 5.

[0050] The chamber 10 houses the sample holder 2, the beam irradiation unit 3, the first microscope unit 4, the second microscope unit 5, and the cover 7. The chamber 10 is formed with an entrance unit 11 for the laser light L, which is configured in the shape of a window and made of a material that transmits the laser light L. The chamber 10 also has an exhaust unit 12 for exhausting the inside of the chamber 10 to reduce the pressure (to create a vacuum). Furthermore, the chamber 10 may be provided with another unit 6 for processing or observing the sample A held in the sample holder 2.

[0051] The laser processing apparatus 20 includes a laser unit 60 including a laser output unit 30 and a laser optical system 40, and a control unit 70. The laser output unit 30 outputs ultrashort pulsed laser light L at a low fluence. The pulse width of the laser light L output from the laser output unit 30 is, for example, 1 ps or less. The low fluence of the laser light L may mean, for example, that the energy density of the laser light L is near the processing threshold of the sample A, which is determined so that ablation processing occurs during laser processing of the sample A. The laser optical system 40 is a laser irradiation unit that irradiates the laser light L output from the laser output unit 30 onto the sample A held in the sample holder 2. The laser light L output from the laser output unit 30 is guided by the laser optical system 40 and incident into the chamber 10 from the incident unit 11.

[0052] The laser optical system 40 has a spatial light modulator 41 and a galvanometer mirror (scanning unit) 43. The spatial light modulator 41 modulates the laser light L output from the laser output unit 30 according to a modulation pattern and emits the modulated laser light. More specifically, the spatial light modulator 41 is, for example, an LCOS-SLM (Liquid Crystal On Silicon - Spatial Light Modulator), and displays a modulation pattern on a liquid crystal layer, thereby modulating the laser light L that enters and exits the liquid crystal layer according to the modulation pattern.

[0053] The galvanometer mirror 43 is used to scan the laser light L output from the laser output unit 30 onto the sample A (target object) placed in the sample holder 2. Specifically, the galvanometer mirror 43 includes mirrors 43a and 43b, and by driving the mirrors 43a and 43b, the laser light L emitted from the spatial light modulator 41 is irradiated onto the sample A held in the sample holder 2 while scanning (hereinafter, this may simply be referred to as "scanning"). As described above, in this embodiment, the laser optical system 40 includes, as a scanning unit, the galvanometer mirror 43, which is an optical element that receives the laser light L emitted from the spatial light modulator 41 and emits the laser light L so as to scan the sample A held in the sample holder 2.

[0054] The laser irradiation unit may include, instead of (or in addition to) the galvanometer mirror, a scanning unit that mechanically moves the sample holder 2 (i.e., sample A) so as to scan the laser light emitted from the spatial light modulator 41 onto the sample A. The laser light L emitted from the galvanometer mirror 43 is focused by a lens 42 toward the sample A. The lens 42 is, for example, an fθ lens.

[0055] The laser optical system 40 has a relay optical system 44. The relay optical system 44 is disposed between the spatial light modulator 41 and the galvanometer mirror 43. The relay optical system 44 includes a pair of lenses 44a and 44b, and is configured to transfer an image of the laser light L modulated by the spatial light modulator 41 onto the lens 42. The laser light L emitted from the spatial light modulator 41 and passed through the relay optical system 44 has its optical path adjusted by predetermined mirrors 56 and 57 and is then supplied to the galvanometer mirror 43.

[0056] The laser optical system 40 further includes a collimating lens 51, an output control unit (adjustment unit) 52, a beam diameter control unit (adjustment unit) 53, a half-wave plate 54, and a polarizing beam splitter 55, which are arranged in this order on the optical path of the laser light L traveling from the laser output unit 30 to the spatial light modulator 41. The collimating lens 51 collimates the laser light L output from the laser output unit 30 and emits it. Therefore, the collimated laser light L is incident on the spatial light modulator 41. The collimating lens 51 may be omitted.

[0057] The output control unit 52 is, for example, an attenuator, and adjusts the output of the laser light L output from the laser output unit 30. The beam diameter control unit 53 is, for example, a beam expander, and adjusts the beam diameter of the laser light L output from the laser output unit 30. In this way, the output control unit 52 and the beam diameter control unit 53 are disposed between the spatial light modulator 41 and the laser output unit 30, and function as adjustment units that adjust the output and beam diameter of the laser light L.

[0058] The half-wave plate 54 changes the polarization direction of the laser light L output from the laser output unit 30. The polarizing beam splitter 55 separates the laser light L, which is output from the laser output unit 30 and enters via the half-wave plate 54, into an s-polarized component and a p-polarized component. The p-polarized component (p-polarized laser light L) is incident on the spatial light modulator 41. As described above, the laser light L that has entered the spatial light modulator 41 is modulated and then enters the chamber 10 via the galvanometer mirror 43, where it is used to scan the sample A.

[0059] The microscope device 1 described above can process the sample A using the focused ion beam from the beam irradiation unit 3 and the laser light L from the laser processing device 20. When the focused ion beam is used, the sample A can be processed with high precision. On the other hand, when the laser light L is used, a large area of ​​the sample A can be processed with high throughput.

[0060] 3 is a perspective view showing an example of processing a sample using the laser processing apparatus shown in FIG. 2. As shown in FIG. 3, when the direction along the optical axis of the laser light L is defined as a first direction D1, the laser processing apparatus 20 can form a recess CV in the sample A by scanning the sample A with the laser light L over a predetermined scanning range along a second direction D2 and a third direction D3. Hereinafter, the inner surface of the recess CV excluding the bottom surface may be referred to as a processed cross section Ls. The processed cross section Ls is one surface of the sample A that is to be observed by the first microscope unit 4 and the second microscope unit 5.

[0061] Fig. 4 is a diagram showing the functional configuration of the control unit shown in Fig. 2. The control unit 70 shown in Fig. 4 is for controlling the laser unit 60, which includes the laser output unit 30 and the laser optical system 40 (laser irradiation unit). The control unit 70 may be configured to control only one of the laser output unit 30 and the laser optical system 40, or may be configured to control both the laser output unit 30 and the laser optical system 40. The control unit 70 is a computer including hardware such as a CPU (Central Processing Unit), memory, and a communication module. Each function of the control unit 70, which will be described later, can be realized by operating these components through a program or the like.

[0062] The control unit 70 has an input receiving unit 71, a setting unit 72, and a laser control unit 73. The input receiving unit 71 receives information input from a user via, for example, an input device. The input receiving unit 71 outputs the received information to the setting unit 72. The setting unit 72 sets the irradiation conditions of the laser light L in the laser unit 60 based on the information output from the input receiving unit 71. The laser control unit 73 controls the laser unit 60 so that scanning with the laser light L is performed according to the irradiation conditions set by the setting unit 72.

[0063] Next, an embodiment of the laser processing method will be described, including specific operations of the control unit 70. The laser processing method according to this embodiment is performed by the above-mentioned laser processing apparatus 20 under the control of the control unit 70. Therefore, in the laser processing method and laser processing apparatus 20 according to this embodiment, the sample A is scanned with laser light L modulated by the spatial light modulator 41.

[0064] Fig. 5 is a flowchart showing one step of the laser processing method according to this embodiment. As shown in Fig. 5, in the laser processing method according to this embodiment, first, the input receiving unit 71 of the control unit 70 receives input from a user (step S101). The input received in step S101 is irradiation conditions including the irradiation energy of the laser light L, the scanning range of the laser light L, the number of scans of the laser light L over the scanning range, the scanning speed of the laser light L, and the position of the focal point of the laser light L. However, step S101 may be omitted as appropriate when the control unit 70 stores the irradiation conditions in advance, for example.

[0065] Next, the setting unit 72 of the control unit 70 sets irradiation conditions including the irradiation energy of the laser light L, the scanning range of the laser light L, the number of scans of the laser light L over the scanning range, the scanning speed of the laser light L, and the position of the focal point of the laser light L, based on the input received by the input receiving unit 71.

[0066] 6 is a plan view from the first direction showing the scanning ranges set on the sample. As shown in FIG. 6, in step S102, the setting unit 72 sets a first scanning range R1, a second scanning range R2, and multiple (here, two) third scanning ranges R3a and R3b. The first scanning range R1, the second scanning range R2, and the third scanning ranges R3a and R3b are ranges along the second direction D2 and the third direction D3, and as an example, are rectangular ranges with the second direction D2 as the longitudinal direction.

[0067] In this embodiment, as viewed from the first direction D1, the third scanning range R3b, the third scanning range R3a, the second scanning range R2, and the first scanning range R1 are nested in this order from outside to inside. That is, in this embodiment, as viewed from the first direction D1, the second scanning range R2 includes the entire first scanning range R1 and extends outside the first scanning range R1 in both the second direction D2 and the third direction D3 (i.e., along the entire circumference). Also, as viewed from the first direction D1, the third scanning range R3a includes the entire second scanning range R2 and extends outside the second scanning range R2 in both the second direction D2 and the third direction D3 (i.e., along the entire circumference).

[0068] Furthermore, the third scanning range R3b includes the entire third scanning range R3a and extends outside the third scanning range Ra in both the second direction D2 and the third direction D3 (i.e., around the entire circumference). Therefore, the area of ​​the first scanning range R1 is smaller than the area of ​​the second scanning range R2, which is smaller than the area of ​​the third scanning range R3a, which is smaller than the area of ​​the third scanning range Rb.

[0069] The setting unit 72 may set scan sets in which the laser light L is scanned multiple times while maintaining constant irradiation conditions. In this case, the setting unit 72 may, for example, set a first scan set under first irradiation conditions for the first scanning range R1, set a second scan set under second irradiation conditions for the second scanning range R2, and set a third scan set under third irradiation conditions for each of the third scanning ranges R3a and R3b. The first irradiation conditions, second irradiation conditions, and third irradiation conditions may be the same or different from each other. Furthermore, the number of scans included in the first scanning set, the number of scans included in the second scanning set, and the number of scans included in each of the third scanning sets may be the same or different from each other.

[0070] In the next step, the laser control unit 73 of the control unit 70 controls the laser unit 60 to scan the laser light L on the sample A under the irradiation conditions set by the setting unit 72 in step S102. Here, first, as shown in Fig. 7, the laser control unit 73 controls the laser unit 60 to scan the laser light L on the sample A over a first scanning range R1, thereby forming a recess CV on the sample A (step S103, first step, first process). Note that (a) of Fig. 7 is a view showing the first scanning range R1 from the first direction D1, and (b) and (c) of Fig. 7 are cross-sectional views showing the laser processing.

[0071] In step S103, the laser control unit 73 controls the laser unit 60 to scan the laser light L over a first scanning range R1 in the second direction D2 and the third direction D3 with the focal point P of the laser light L positioned on the surface As of the sample A. In step S103, the laser control unit 73 can control the laser unit 60 to scan the first scanning range R1 with the laser light L a plurality of times (for example, the number of scans set by the setting unit 72, or the first scan set). As a result, a recess CV opening on the surface As is formed in the sample A, and a processed cross section Ls that is the inner surface of the recess CV is formed.

[0072] Here, since the laser light L is scanned over the rectangular first scanning range R1, the recess CV also has a rectangular shape corresponding to the first scanning range R1 when viewed from the first direction D1. Therefore, the recess CV includes a pair of processed cross sections Ls facing the second direction D2 and a pair of processed cross sections Ls facing the third direction D3. In step S103, the recess CV is formed so that the processed cross sections Ls facing the second direction D2 and the processed cross sections Ls facing the third direction D3 are inclined with respect to the first direction D1. As a result, the recess CV has a truncated pyramid shape that narrows toward the bottom of the recess CV.

[0073] In the next step, the laser control unit 73 controls the laser unit 60 to move the position of the focal point P of the laser light L in the first direction D1 toward the bottom surface of the recess CV formed in step S103 (step S104, third step). As shown in Fig. 8, in step S104, the laser control unit 73 positions the focal point P on the bottom surface of the recess CV. Note that (a) of Fig. 8 is a view from the first direction D1 showing the first scanning range R1 and the second scanning range R2, and (b) and (c) of Fig. 8 are cross-sectional views showing the laser processing.

[0074] Subsequently, under the irradiation conditions set by the setting unit 72 in step S102, the laser unit 60 is controlled to scan the sample A with the laser light L. Here, the laser control unit 73 controls the laser unit 60 to scan the second scanning range R2 with the laser light L in the second direction D2 and the third direction D3 in a state where the focal point P of the laser light L is positioned on the bottom surface of the recess CV (i.e., in a state where the focal point P is aligned with the position to which it was moved in step S104) (step S105, second step, second process).

[0075] In step S105, the laser control unit 73 can control the laser unit 60 to scan the second scanning range R2 with the laser light L multiple times (for example, the number of scans set by the setting unit 72, or the second scan set). The number of scans with the laser light L in step S103 and the number of scans with the laser light L in step S105 may be the same as or different from each other. Furthermore, the irradiation energy of the laser light L in step S103 and the irradiation energy of the laser light L in step S105 are, for example, the same.

[0076] As described above, the second scanning range R2 extends outside the first scanning range R1. Therefore, in step S105, the laser light L is scanned so as to straddle the processing cross section Ls of the recess CV formed in step S103. As a result, the recess CV is expanded in the first direction D1, and also expanded in the second direction D2 and the third direction D3 so as to have a shape corresponding to the second scanning range R2. As a result, four new processing cross sections Ls facing the second direction D2 and the third direction D3 are formed in the recess CV.

[0077] In addition, in the second direction D2, the length of the portion of the second scanning range R2 located outside the first scanning range R1 (expansion pitch EP of the scanning range) is smaller than the length LLs from one end to the other end in the first direction D1 of the processing cross section Ls, which is the inner surface facing the second direction D2 of the recess CV formed in step S103. Furthermore, the expansion length of the recess CV in the first direction D1 in step S105 may be larger than the expansion length of the recess CV in the second direction D2 and the third direction D3 in step S105. In addition, the expansion length of the recess CV in the second direction D2 (and the third direction D3) is the expansion pitch EP, and the expansion length of the recess CV in the first direction D1 is, for example, the difference between the depth of the recess CV formed in step S103 and the recess CV formed in step S105.

[0078] In the next step, the laser control unit 73 controls the laser unit 60 to move the position of the focal point P of the laser light L in the first direction D1 toward the bottom surface of the recess CV formed in step S105 (step S106, sixth step). As shown in Fig. 9, in step S106, the laser control unit 73 positions the focal point P on the bottom surface of the recess CV. Note that Fig. 9(a) is a view from the first direction D1 showing the first scanning range R1, the second scanning range R2, and the third scanning range R3a, and Fig. 9(b) and (c) are cross-sectional views showing the laser processing.

[0079] Subsequently, under the irradiation conditions set by the setting unit 72 in step S102, the laser unit 60 is controlled to scan the sample A with the laser light L. Here, the laser control unit 73 controls the laser unit 60 to scan the third scanning range R3a with the laser light L in the second direction D2 and the third direction D3 in a state where the focal point P of the laser light L is positioned on the bottom surface of the recess CV (i.e., in a state where the focal point P is aligned with the position to which it was moved in step S106) (step S107, fifth step).

[0080] In step S107, the laser control unit 73 can control the laser unit 60 to scan the third scanning range R3a with the laser light L a plurality of times (for example, the number of scans set by the setting unit 72, or the third scan set). The number of scans with the laser light L in steps S103 and S105 and the number of scans with the laser light L in step S107 may be the same as or different from each other. Furthermore, the irradiation energy of the laser light L in steps S103 and S105 and the irradiation energy of the laser light L in step S107 are, for example, the same.

[0081] As described above, the third scanning range R3a extends outside the second scanning range R2. Therefore, in step S107, the laser light L is scanned so as to straddle the processing cross-section Ls of the recess CV formed in step S105. This causes the recess CV to expand in the first direction D1, and also expands the recess CV in the second direction D2 and the third direction D3 so as to have a shape corresponding to the third scanning range R3a. As a result, four new processing cross-sections Ls facing the second direction D2 and the third direction D3 are formed in the recess CV.

[0082] In addition, in the second direction D2, the length (enlargement pitch, not shown) of the portion of the third scanning range R3a located outside the second scanning range R2 is smaller than the length (not shown) from one end to the other end in the first direction D1 of the processed cross section Ls, which is the inner surface facing the second direction D2 of the recess CV formed in step S105. Furthermore, the enlargement length of the recess CV in the first direction D1 in step S107 may be larger than the enlargement length of the recess CV in the second direction D2 and the third direction D3 in step S107 (here, the difference between the depth of the recess CV formed in step S105 and the depth of the recess CV formed in step S107).

[0083] In this embodiment, steps S106 and S107 are performed multiple times (here, twice). That is, in the subsequent step, as shown in Fig. 10, step S106 is performed again to move the position in the first direction D1 of the focal point P of the laser light L toward the bottom surface of the recess CV formed in the first step S107. Then, step S107 is performed again to scan the third scanning range R3b with the laser light L multiple times (for example, the number of scans set by the setting unit 72 or the third scan set). The number of scans with the laser light L here may be the same as or different from the number of scans with the laser light L in the first step S107.

[0084] As described above, the third scanning range R3b extends outside the third scanning range R3a. Therefore, in the second step S107, the laser light L is scanned so as to straddle the processing cross section Ls of the recess CV formed in the first step S107. This causes the recess CV to expand in the first direction D1, and also in the second direction D2 and the third direction D3 so as to have a shape corresponding to the third scanning range R3b. As a result, four new processing cross sections Ls facing the second direction D2 and the third direction D3 are formed in the recess CV.

[0085] In addition, in the second direction D2, the length (enlargement pitch, not shown) of the portion of the third scanning range R3b located outside the third scanning range R3a is smaller than the length (not shown) from one end to the other end in the first direction D1 of the processed cross section Ls, which is the inner surface facing the second direction D2 of the recess CV formed in the first step S107. Furthermore, the enlarged length of the recess CV in the first direction D1 in the second step S107 may be larger than the enlarged length of the recess CV in the second direction D2 and the third direction D3 in the second step S107 (here, the difference between the depth of the recess CV formed in the first step S107 and the depth of the recess CV formed in the second step S107).

[0086] Thereafter, steps S106 and S107 may be further performed. Alternatively, steps S106 and S107 from the second time onwards may not be performed. That is, the laser processing method according to this embodiment may include one or more steps S107 (and step S106) depending on the depth of the recess CV to be formed in the sample A. Furthermore, when there are multiple steps S107, multiple steps S107 may be performed so that the third scanning range in one step S107 (e.g., third scanning range R3b) includes the third scanning range in another step S107 before the one step S107 (e.g., third scanning range R3a) and extends outside the third scanning range in the other step S107 at least in the second direction D2.

[0087] Here, when the setting unit 72 sets the scanning sets, at least two scanning sets are set: a first scanning set relating to scanning the first scanning range R1 with the laser light L in step S103, and a second scanning set relating to scanning the second scanning range R2 with the laser light L in step S105. In particular, when step S107 is performed at least once, a third scanning set relating to scanning the third scanning range (e.g., third scanning ranges R3a and R3b) with the laser light L in step S107 is further set. In this way, the setting unit 72 has a function to set multiple scanning sets, and the number of scanning sets that the setting unit 72 can set may be three or more. Furthermore, when multiple scanning sets are set by the setting unit 72 as described above, the laser control unit 73 may have a function to control the laser unit 60 to execute the multiple scanning sets consecutively.

[0088] In the next step, the processed cross section Ls of the recess CV is observed by the first microscope unit 4 and / or the second microscope unit 5 (step S108, fourth step). Here, as an example, of the processed cross sections Ls of the recess CV, the processed cross section Ls facing the second direction D2 can be observed.

[0089] As described above, in the laser processing method and laser processing apparatus 20 according to this embodiment, first, the laser light L is scanned over the sample A over a first scanning range R1 along the second direction D2 and the third direction D3, thereby forming a recess CV in the sample A (step S103, first step, first process). Then, the laser light L is scanned over the sample A over a second scanning range R2 along the second direction D2 and the third direction D3 (step S105, second step, second process). As a result, the recess CV is enlarged in the first direction D1, the second direction D2, and the third direction D3.

[0090] At this time, the second scanning range R2, when viewed from the first direction D1, includes the first scanning range R1 and extends at least outside the first scanning range R1 in the second direction D2. As a result, in step S105, the laser beam L is scanned across the outer edge (i.e., the processed cross section Ls facing the second direction D2) of the recess CV formed in step S103 according to the first scanning range R1, thereby forming a new processed cross section Ls. As a result, the energy of the laser beam L is newly used for processing (i.e., the energy is prevented from accumulating as heat), making it possible to obtain a high-quality processed cross section Ls with reduced thermal effects. In this way, the laser processing method and laser processing apparatus 20 according to this embodiment can suppress deterioration of processing quality.

[0091] Figure 11 is an SEM image showing the observation result of a processed cross section formed by the laser processing method and laser processing apparatus according to this embodiment. Figure 11(a) shows a secondary electron image, and Figure 11(b) shows a backscattered electron image. As shown in Figure 11, it can be seen that the laser processing method and laser processing apparatus according to this embodiment can obtain a processed cross section Ls of good quality in which thermal effects are suppressed. Note that the area AR in Figures 11(a) and (b) is an enlarged view.

[0092] Furthermore, the laser processing method according to this embodiment includes step S104, which is performed after step S103 and before step S105, of moving the position of the focal point P of the laser light L in the first direction D1 toward the bottom surface of the recess CV. Then, in step S105, scanning is performed with the laser light L in a state where the focal point P is aligned with the position to which it was moved in step S104. This makes it possible to more efficiently enlarge the recess CV in the first direction D1.

[0093] Furthermore, the laser processing method according to this embodiment includes, after step S105, step S108 of observing, with a microscope, the processed cross section Ls, which is the inner surface of the recess CV facing the second direction D2. Therefore, it is possible to observe the processed cross section Ls with good quality.

[0094] Furthermore, in the laser processing method according to this embodiment, the recess CV is formed so that the processing cross section Ls, which is the inner surface of the recess CV facing the second direction D2, is inclined with respect to the first direction D1. In this way, the processing cross section Ls of the recess CV facing the second direction D2 may be inclined with respect to the first direction D1.

[0095] In the laser processing method according to this embodiment, the second scanning range R2 extends outside the first scanning range R1 in the second direction D2 and the third direction D3 when viewed from the first direction D1, which prevents deterioration in the quality of the processed cross section Ls facing the second direction D2 and the processed cross section Ls facing the third direction D3.

[0096] Furthermore, in the laser processing method according to this embodiment, the length of the portion of the second scanning range R2 located outside the first scanning range R1 in the second direction D2 (expansion pitch Ep of the scanning range) is smaller than the length LLs from one end to the other end in the first direction D1 of the processing cross section Ls of the recess CV formed in step S103, which faces the second direction D2. This prevents steps from being generated in the processing cross section Ls of the recess CV, which faces the second direction D2.

[0097] Furthermore, in the laser processing method according to this embodiment, in step S103, the first scanning range R1 may be scanned multiple times with the laser light L. In this way, by scanning the first scanning range R1 multiple times with the laser light L, it is possible to form deeper recesses CV in the first direction D1.

[0098] Furthermore, in the laser processing method according to the present embodiment, in step S105, the second scanning range R2 may be scanned with the laser light L multiple times, and the number of scans with the laser light L in step S103 and the number of scans with the laser light L in step S105 may be the same. Alternatively, the number of scans with the laser light L in step S103 and the number of scans with the laser light L in step S105 may be different from each other.

[0099] In this way, by scanning the second scanning range R2 with the laser light L multiple times, a deeper recess CV can be formed in the first direction D1. In this case, the number of scans of the first scanning range R1 with the laser light L and the number of scans of the second scanning range R2 with the laser light L may be the same or different. In other words, the number of scans of the first scanning range R1 with the laser light L and the number of scans of the second scanning range R2 with the laser light L can be appropriately set according to the requirements of the processed cross section Ls.

[0100] In the laser processing method according to this embodiment, the area of ​​the first scanning range R1 is smaller than the area of ​​the second scanning range R2. In this way, the relationship between the area of ​​the first scanning range R1 and the area of ​​the second scanning range R2 can be appropriately set according to the requirements of the shape of the recess CV.

[0101] Furthermore, in the laser processing method according to this embodiment, the pulse width of the laser light L is 1 ps or less. Therefore, the sample A is processed by ablation processing, and it is possible to obtain a processed cross section Ls of good quality with thermal effects further suppressed.

[0102] Furthermore, in the laser processing method according to this embodiment, in step S105, the expanded length of the recess CV in the first direction D1 is greater than the expanded length of the recess CV in the second direction D2. Therefore, it is possible to form a deeper recess CV in the first direction D1 while suppressing deterioration in the quality of the processed cross section Ls.

[0103] Furthermore, in the laser processing method according to this embodiment, the magnitude of the irradiation energy of the laser light L in step S103 is the same as the magnitude of the irradiation energy of the laser light L in step S105. Therefore, there is no need to change the energy of the laser light L between step S103 and step S105, which facilitates control.

[0104] Moreover, in the laser processing method according to this embodiment, the laser light L modulated by the spatial light modulator 41 is scanned onto the sample A. In this manner, processing may be performed using the laser light L modulated by the spatial light modulator 41.

[0105] Furthermore, the laser processing method according to this embodiment includes, after step S105, one or more steps S107 in which the sample A is scanned with the laser light L over a third scanning range (e.g., third scanning ranges R3a and R3b) along the second direction D2 and the third direction D3. The third scanning range includes the second scanning range R2 when viewed from the first direction D1, and extends outside the second scanning range R2 in the second direction D2 and the third direction D3. In step S107, the sample A is scanned with the laser light L over the third scanning range, thereby enlarging the recess CV in the first direction D1, the second direction D2, and the third direction D3. This allows for the formation of a deeper recess CV in the first direction D1 while suppressing deterioration in the quality of the processed cross section Ls.

[0106] Furthermore, in the laser processing method according to this embodiment, when there are multiple steps S107, the multiple steps S107 are performed so that the third scanning range in one step S107 (for example, the third scanning range R3b) includes the third scanning range in another step S107 before the one step S107 (for example, the third scanning range R3a) and extends to the outside of the third scanning range in the other step S107 in the second direction D2 and the third direction D3. Therefore, it is possible to form a deeper recess CV in the first direction D1 while reliably suppressing deterioration in the quality of the processed cross section Ls.

[0107] Furthermore, the laser processing method according to this embodiment includes step S106, which is performed after step S105 and before step S107, in which the position of the focal point P of the laser light L in the first direction D1 is moved toward the bottom surface of the recess CV. Then, in step S107, scanning is performed with the laser light L in a state in which the focal point P is aligned with the position to which it was moved in step S106. This makes it possible to more efficiently enlarge the recess CV in the first direction D1.

[0108] The laser processing apparatus 20 according to this embodiment includes a sample holder 2 on which a sample A is placed, a laser unit 60 including a laser output unit 30 that outputs laser light L and a laser optical system 40 for irradiating the sample A placed on the sample holder 2 with the laser light L output from the laser output unit 30, and a control unit 70 that controls the laser unit 60. The laser optical system 40 includes a spatial light modulator 41 that modulates and emits the laser light L output from the laser output unit 30, and a galvanometer mirror 43 that scans the sample A placed on the sample holder 2 with the laser light L output from the spatial light modulator 41. The control unit 70 includes a setting unit 72 that receives input and sets irradiation conditions including the scanning range of the laser light L, the number of scans to scan the laser light L over the scanning range, and the position of the focal point P of the laser light L, and a laser control unit 73 that controls the laser unit 60 to scan the sample A with the laser light L under the irradiation conditions set by the setting unit 72.

[0109] In this laser processing apparatus 20, the control unit 70, for example, by receiving input from a user, sets irradiation conditions including the scanning range of the laser light L, the number of scans of the laser light L across the scanning range, and the position of the focal point P of the laser light L, and scans the sample A with the laser light under these irradiation conditions. This makes it possible to obtain a processed cross section Ls of good quality. In this way, with this laser processing apparatus 20, it is possible to suppress deterioration of processing quality.

[0110] Furthermore, in the laser processing apparatus 20 according to this embodiment, the setting unit 72 may have a function of setting a scan set in which, while maintaining constant irradiation conditions, multiple scans are performed with the laser light L. In this case, processing can be performed in which multiple scans with the laser light L under constant irradiation conditions are treated as one scan set.

[0111] Furthermore, in the laser processing apparatus 20 according to this embodiment, the setting unit 72 may have a function of setting a plurality of scanning sets, and the laser control unit 73 may have a function of controlling the laser unit 60 to execute the plurality of scanning sets consecutively when the plurality of scanning sets are set in the setting unit 72. In this case, consecutive processing using the plurality of scanning sets can be easily performed.

[0112] Furthermore, in the laser processing apparatus 20 according to this embodiment, the number of scan sets that can be set by the setting unit 72 may be three or more. In this case, it becomes possible to easily perform continuous processing using a larger number of scan sets.

[0113] The above embodiment has described one aspect of the present invention. Therefore, the present invention can be realized by any modification of the above-described laser processing method and laser processing apparatus. Next, modifications will be described. [First Modification]

[0114] In the above embodiment, the second scanning range R2 includes the entire first scanning range and extends outside the first scanning range R1 in both the second direction D2 and the third direction D3 (i.e., all around the circumference). The same applies to the relationship between the third scanning range R3a and the second scanning range R2, and the relationship between the third scanning range R3b and the third scanning range R3a.

[0115] 12(a), the first scanning range R1 and the second scanning range R2 may be set so that, when viewed from the first direction D1, the second scanning range R2 includes the entire first scanning range R1, but extends outside the first scanning range R1 in the third direction D3, and extends outside the first scanning range R1 only on one side of the second direction D2 (here, the positive side, the scanning end side). The same applies to the relationship between the third scanning range R3a and the second scanning range R2, and the relationship between the third scanning range R3b and the third scanning range R3a. That is, in this case, when viewed from the first direction D1, the ends of the first scanning range R1, the second scanning range R2, the third scanning range R3a, and the third scanning range R3b on the other side of the second direction D2 (here, the negative side, the scanning start side) are aligned with each other.

[0116] 12(b), the first scanning range R1 and the second scanning range R2 may be set so that, when viewed from the first direction D1, the second scanning range R2 includes the entire first scanning range R1, but extends outside the first scanning range R1 only on one side of the second direction D2 (here, the positive side, the scanning end side) of the second direction D2 and the third direction D3. The same applies to the relationship between the third scanning range R3a and the second scanning range R2, and the relationship between the third scanning range R3b and the third scanning range R3a. That is, in this case, when viewed from the first direction D1, the ends of the first scanning range R1, the second scanning range R2, the third scanning range R3a, and the third scanning range R3b on the other side of the second direction D2 (here, the negative side, the scanning start side) and both ends in the third direction D3 are aligned with each other.

[0117] In both cases (a) and (b) of Figure 12, the area of ​​the first scanning range R1 is smaller than the area of ​​the second scanning range R2, the area of ​​the second scanning range R2 is smaller than the area of ​​the third scanning range R3a, and the area of ​​the third scanning range R3a is smaller than the area of ​​the third scanning range R3b.

[0118] When the first scanning range R1, the second scanning range R2, and the third scanning ranges R3a and R3b are set as described above, in step S103, step S105, the first step S107, and the second step S107, processing progresses as shown in Figure 13 when viewed from the third direction D3. That is, as shown in (a) of Figure 13, in step S103, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the first scanning range R1 along the second direction D2 and the third direction D3, thereby forming a recess CV corresponding to the first scanning range R1.

[0119] 13(b), in step S105, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the second scanning range R2 in the second direction D2 and the third direction D3, thereby enlarging the recess CV formed in step S103 in the first direction D1 and also enlarging the recess CV on one side in the second direction D2 so that it has a shape corresponding to the second scanning range R2. Therefore, in step S105, the processed cross section Ls formed in step S103 is maintained on the other side in the second direction D2, and a new processed cross section Ls is formed on one side in the second direction D2.

[0120] 12(a), if the second scanning range R2 also extends outside the first scanning range R1 in the third direction D3, the recess CV formed in step S103 is also enlarged in the third direction D3 in step S105. Furthermore, if both ends of the second scanning range R2 in the third direction D3 coincide with the first scanning range R1 as shown in FIG. 12(b), the recess CV formed in step S103 is not enlarged in the third direction D3 in step S105, and the processed cross section Ls of the recess CV facing the third direction D3 is maintained.

[0121] 13(c), in the first step S107, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the third scanning range R3a in the second direction D2 and the third direction D3, thereby enlarging the recess CV formed in step S105 in the first direction D1 and also enlarging the recess CV on one side in the second direction D2 so that it has a shape corresponding to the third scanning range R3a. Therefore, in the first step S107, the processed cross section Ls formed in step S105 is maintained on the other side in the second direction D2, and a new processed cross section Ls is formed on one side in the second direction D2.

[0122] 12(a), if the third scanning range R3a also extends outside the second scanning range R2 in the third direction D3, the recess CV formed in step S105 is also enlarged in the third direction D3 in the first step S107. Also, if both ends of the third scanning range R3a in the third direction D3 coincide with the second scanning range R2 as shown in FIG. 12(b), the recess CV formed in step S105 is not enlarged in the third direction D3 in the first step S107, and the processed cross section Ls of the recess CV facing the third direction D3 is maintained.

[0123] 13(d), in the second step S107, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the third scanning range R3b in the second direction D2 and the third direction D3, thereby enlarging the recess CV formed in the first step S107 in the first direction D1 and also enlarging the recess CV on one side in the second direction D2 so that it has a shape corresponding to the third scanning range R3b. Therefore, in the second step S107, the processed cross section Ls formed in the first step S107 is maintained on the other side in the second direction D2, and a new processed cross section Ls is formed on one side in the second direction D2.

[0124] 12(a), if the third scanning range R3b extends outside the third scanning range R3a in the third direction D3 as well, then in the second step S107, the recess CV formed in the first step S107 is enlarged in the third direction D3 as well. Furthermore, if both ends of the third scanning range R3b in the third direction D3 coincide with the third scanning range R3a as shown in FIG. 12(b), then in the second step S107, the recess CV formed in the first step S107 is not enlarged in the third direction D3, and the processed cross section Ls of the recess CV facing the third direction D3 is maintained.

[0125] As described above, the second scanning range R2, when viewed from the first direction D1, needs only to include the entire first scanning range R1 and extend outside the first scanning range R1 on at least one side in the second direction D2. Furthermore, the second scanning range R2, when viewed from the first direction D1, may extend outside the first scanning range R1 only on one side in the second direction D2. In this case, deterioration in the quality of one processing cross section Ls facing the second direction D2 is suppressed. In other words, it is possible to ensure the minimum quality of the processing cross section Ls used for observation. [Second Modification]

[0126] FIG. 14 is a plan view from the first direction to explain a scanning range according to another modified example. In the example shown in FIG. 14, the first scanning range R1, the second scanning range R2, the third scanning range R3a, and the third scanning range R3b are set to sequentially shift to one side of the second direction D2 (here, the positive side, toward the end point of the scan). Therefore, when viewed from the first direction D1, the second scanning range R2 includes a portion of the first scanning range R1 (here, most of the first scanning range R1 except for the end on the other side of the second direction D2), and extends outside the first scanning range R1 only on one side of the second direction. The same applies to the relationship between the third scanning range R3a and the second scanning range R2, and the relationship between the third scanning range R3b and the third scanning range R3a.

[0127] In this example, when viewed from the first direction D1, the ends of the first scanning range R1, the second scanning range R2, the third scanning range R3a, and the third scanning range R3b on both sides of the third direction D3 are aligned with each other. Furthermore, the areas of the first scanning range R1, the second scanning range R2, the third scanning range R3a, and the third scanning range R3b are identical. More specifically, when viewed from the first direction D1, the first scanning range R1, the second scanning range R2, the third scanning range R3a, and the third scanning range R3b are identical in shape. That is, in the example of FIG. 14, multiple scanning ranges of the same shape are set to shift sequentially to one side of the second direction D2.

[0128] When the first scanning range R1, the second scanning range R2, and the third scanning ranges R3a and R3b are set as described above, in step S103, step S105, the first step S107, and the second step S107, processing progresses as shown in FIG. 15 when viewed from the third direction D3. That is, as shown in (a) of FIG. 15, in step S103, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the first scanning range R1 along the second direction D2 and the third direction D3, thereby forming a recess CV corresponding to the first scanning range R1.

[0129] 15B, in step S105, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the second scanning range R2 in the second direction D2 and the third direction D3, thereby enlarging the recess CV formed in step S103 in the first direction D1. At the same time, the recess CV is enlarged on one side of the second direction D2 to correspond to the shift of the second scanning range R2 from the first scanning range R1, and the recess CV is reduced on the other side of the second direction D2 to correspond to the shift of the second scanning range R2 from the first scanning range R1. Therefore, in step S105, the processed cross section Ls formed in step S103 is maintained on the other side of the second direction D2, and a step is formed between the processed cross section Ls formed in step S103 and the new processed cross section Ls formed in step S105. Meanwhile, a new processed cross section Ls is formed on one side of the second direction D2.

[0130] 15(c), in the first step S107, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the third scanning range R3a in the second direction D2 and the third direction D3, thereby enlarging the recess CV formed in step S105 in the first direction D1. At the same time, the recess CV is enlarged on one side of the second direction D2 to correspond to the shift of the third scanning range R3a from the second scanning range R2, and the recess CV is reduced on the other side of the second direction D2 to correspond to the shift of the third scanning range R3a from the second scanning range R2. Therefore, in the first step S107, the processed cross section Ls formed in step S105 is maintained on the other side of the second direction D2, and a step is formed between the processed cross section Ls formed in step S105 and the new processed cross section Ls formed in the first step S107. Meanwhile, a new processed cross section Ls is formed on one side of the second direction D2.

[0131] 15(d), in the second step S107, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the third scanning range R3b in the second direction D2 and the third direction D3, thereby enlarging the recess CV formed in the first step S107 in the first direction D1. At the same time, the recess CV is enlarged on one side in the second direction D2 to correspond to the shift of the third scanning range R3b from the third scanning range R3a, and the recess CV is reduced on the other side in the second direction D2 to correspond to the shift of the third scanning range R3b from the third scanning range R3a. Therefore, in the second step S107, the processed cross section Ls formed in the first step S107 is maintained on the other side in the second direction D2, and a step is formed between the processed cross section Ls formed in the first step S107 and the new processed cross section Ls formed in the second step S107. On the other hand, a new processed cross section Ls is formed on one side in the second direction D2.

[0132] As described above, the area of ​​the first scanning range R1 may be the same as the area of ​​the second scanning range R2. Furthermore, the second scanning range R2 may include a portion of the first scanning range R1 when viewed from the first direction D1, and may extend outside the first scanning range R1 only on one side in the second direction D2. In this case, deterioration in the quality of one processed cross section Ls facing the second direction D2 is suppressed. In other words, it is possible to ensure the minimum quality of the processed cross section Ls used for observation. [Third Modification]

[0133] In the above embodiment, the irradiation energy of the laser light L in step S103 and the irradiation energy of the laser light L in step S105 (and further the irradiation energy in step S107) are, for example, the same. However, the magnitude of the irradiation energy of the laser light L in step S103 may be greater than the magnitude of the irradiation energy of the laser light L in step S105 (and further the irradiation energy in step S107) so that rough processing is performed first and then finish processing is performed.

[0134] That is, as shown in (a) of Figure 16, in step S103, the laser control unit 73 controls the laser unit 60 to scan the first scanning range R1 with laser light Lh (laser light L) having relatively high irradiation energy along the second direction D2 and the third direction D3, thereby forming a recess CV corresponding to the first scanning range R1 as shown in (b) of Figure 16.

[0135] Next, as shown in (b) of Figure 16, in step S105, the laser control unit 73 controls the laser unit 60 to scan the second scanning range R2 with laser light Lw (laser light L) having relatively low irradiation energy along the second direction D2 and the third direction D3, thereby expanding the recess CV in the first direction D1 as shown in (c) of Figure 16, and also expanding the recess CV in the second direction D2 and the third direction D3 so that it has a shape corresponding to the second scanning range R2.

[0136] The relationship between the first scanning range R1 and the second scanning range R2 is the same as the relationship shown in Fig. 8(a). Therefore, in step S105, the laser light Lw is scanned across the machined cross section Ls formed in step S103 in both the second direction D2 and the third direction D3, and a new machined cross section Ls is formed. At this time, the inclination of the new machined cross section Ls formed in step S105 is gentler than the inclination of the machined cross section Ls formed in step S103 (the angle with respect to the first direction D1 is larger).

[0137] Similarly, as shown in (c) of Figure 16, in step S107, the laser control unit 73 controls the laser unit 60 to again scan the second scanning range R2 with laser light Lw (laser light L) having relatively low irradiation energy along the second direction D2 and the third direction D3, thereby expanding the recess CV in the first direction D1 as shown in (d) of Figure 16, and also expanding the recess CV in the second direction D2 and the third direction D3 so that it has a shape corresponding to the second scanning range R2.

[0138] In this way, in step S107, scanning with the low-energy laser light Lw is performed while maintaining the scanning range constant from step S105. As a result, the inclination of the newly formed processed cross section Ls becomes gentler than the inclination of the processed cross section Ls formed in step S105 (the angle with respect to the first direction D1 becomes larger).

[0139] As described above, by making the magnitude of the irradiation energy of the laser light L in step S103 greater than the magnitude of the irradiation energy of the laser light L in step S105 (and step S107), the takt time can be shortened. [Fourth Modification]

[0140] Here, the expansion pitch EP of the second scanning range R2 relative to the first scanning range R1 can be adjusted as appropriate. For example, first, in step S103, the laser control unit 73 controls the laser unit 60 to scan the first scanning range R1 with the laser light L in the second direction D2 and the third direction D3, thereby forming recesses CV corresponding to the first scanning range R1, as shown in (a) of FIG.

[0141] Next, in step S105, the laser control unit 73 controls the laser unit 60 to scan the laser light L over the second scanning range R2 in the second direction D2 and the third direction D3, thereby enlarging the recess CV in the first direction D1 and also enlarging the recess CV in the second direction D2 and the third direction D3 so as to have a shape corresponding to the second scanning range R2, as shown in FIG. 17(b). At this time, the enlarged pitch EP can be adjusted so that the inclination (angle with respect to the first direction D1 (same below)) of the processed cross section Ls formed in step S103 is equal to the inclination of the processed cross section Ls formed in step S105 (so that the inclination does not change). This enlarged pitch EP is used as the reference pitch.

[0142] In contrast, as shown in (c) of Figure 17, when the expansion pitch EP is made narrower than the reference pitch and the laser light L is scanned along the second direction D2 and the third direction D3 over the second scanning range R2 to expand the recess CV, the slope of the newly formed processed cross section Ls becomes steeper (the angle with respect to the first direction D1 becomes smaller).

[0143] FIG. 18 is an SEM image showing the processing results when multiple scan sets are performed with the expanded pitch EP narrower than the reference pitch, as shown in FIG. 17(c). FIG. 19 is a graph showing the measurement results of the displacement of the recess surface (i.e., a diagram showing the cross-sectional shape of the recess). FIGS. 18(a) and 19(a) show the results when two scan sets are performed, where the depth of the recess CV is 30 μm and the angle of the processed cross section Ls with respect to the first direction D1 is 38.8°. FIG. 18(b) shows the results when 13 scan sets are performed, where the depth of the recess CV is 200 μm and the angle of the processed cross section Ls with respect to the first direction D1 is 23.8°. It can be seen that by continuing processing with the expanded pitch EP narrower than the reference pitch, the slope of the processed cross section Ls becomes steeper.

[0144] 18(c) and 19(b) show the case where 18 scan sets were performed, the depth of the recess CV was 270 μm, and the angle of the processed cross section Ls with respect to the first direction D1 was 23.3°. As such, it can be understood that even if processing is continued for a certain period or more with the expanded pitch EP narrower than the reference pitch, the slope of the processed cross section Ls is unlikely to change.

[0145] 17(d), when the laser beam L is scanned along the second direction D2 and the third direction D3 over the second scanning range R2 to enlarge the recess CV in a state where the enlargement pitch EP is adjusted to be wider than the reference pitch to a certain extent, a step (a flat surface along the second direction D2 and the third direction D3) appears on the newly formed processed cross section Ls. In order to prevent a step from occurring on the processed cross section Ls, for example, as shown in FIG. 8(a), one idea is to make the enlargement pitch Ep smaller than the length LLs from one end to the other end in the first direction D1 of the processed cross section Ls facing the second direction D2 of the recess CV formed in step S103.

[0146] As described above, by adjusting the expansion pitch EP, it is possible to change the inclination of the processed cross section Ls, or to create a step in the processed cross section Ls (or to prevent a step from being created).

[0147] Even with a constant expansion pitch EP, increasing the irradiation energy (pulse energy) of the laser light L may cause thermal effects on the machined cross section Ls, resulting in a deterioration in the quality of the machined cross section Ls. For example, Figure 20 shows SEM images (left: secondary electron image, right: backscattered electron image) showing the machined cross section Ls when the pulse energy is 1.5 μJ and the expansion pitch EP is 3.5 μm. In this case, the thermal effects on the machined cross section Ls are reduced, and a machined cross section Ls of good quality is obtained.

[0148] On the other hand, Figure 21 shows SEM images (left: secondary electron image, right: backscattered electron image) showing the processed cross section Ls when the pulse energy is increased to 2.0 μJ and the expansion pitch EP is maintained at 3.5 μm. As shown in Figure 21, in this case, the processed cross section Ls is thermally affected, resulting in a deterioration in quality.

[0149] In contrast, Figure 22 is an SEM image (left: secondary electron image, right: backscattered electron image) showing the processed cross section Ls when the pulse energy is increased to 2.0 μJ and the expansion pitch EP is expanded to 6.0 μm. In this case, by increasing the irradiation energy of the laser light L and expanding the expansion pitch EP, the thermal effect on the processed cross section Ls is reduced, and a processed cross section Ls of good quality is obtained. [Fifth Modification]

[0150] In the above embodiment, step S104 is performed before step S105, and the focal point P of the laser light L is moved toward the bottom surface of the recess CV. Similarly, step S106 is performed before step S107, and the focal point P of the laser light L is moved toward the bottom surface of the recess CV. However, whether or not to move the focal point P in this manner can be selected appropriately. For example, the necessity for moving the focal point P changes depending on whether the depth of the recess CV (i.e., the processing depth) is sufficiently shallow or deep compared to the Rayleigh length.

[0151] For example, as shown in (a) and (b) of Figure 23, in step S103, a shallow recess CV is formed by scanning laser light L over a first scanning range R1, and then, as shown in (b) of Figure 23, step S104 is performed to move the focal point P of the laser light L toward the bottom surface of the recess CV (aligned with the bottom surface), and then step S105 is performed to scan laser light L over a second scanning range R2 to slightly enlarge the recess CV.

[0152] Thus, when the processing depth is shallow, as shown in (c) of Figure 23, whether steps S104 and S106 are performed to move the focal point P of the laser light L toward the bottom surface of the recess CV (aligned with the bottom surface), or whether the focal point P of the laser light L is positioned on the surface As of the sample A, the processing results obtained by performing step S107 to scan the laser light L over the third scanning range R3a are the same.

[0153] On the other hand, as shown in (a) of Figure 24, in step S103, after forming a deep recess CV by scanning laser light L over the first scanning range R1, the subsequent processing results will be different depending on whether step S104 is performed to move the focal point P of the laser light L toward the bottom side of the recess CV (aligned with the bottom surface) as shown in (b) of Figure 24, or whether the focal point P of the laser light L is positioned on the surface As of the sample A.

[0154] When step S104 is performed and the focal point P of the laser beam L is moved toward the bottom surface of the recess CV (aligned with the bottom surface), a processed cross section Ls without any steps is formed as shown in (c) of Fig. 24. However, when the focal point P of the laser beam L is positioned on the surface As of the sample A, steps (flat surfaces along the second direction D2 and the third direction D3) may occur on the processed cross section Ls as shown in (d) of Fig. 24. In this way, when the processing depth is deep, steps can be prevented from occurring on the processed cross section Ls by moving the focal point P toward the bottom surface of the recess CV.

[0155] Furthermore, if the distance from the focal point P of the laser light L to the processing surface (for example, the distance from the surface As of the sample A to the bottom surface of the recess CV) is within the Rayleigh length, the laser light L can be used to process the sample A sufficiently, and if the distance is up to about twice the Rayleigh length, the laser light L can be used to process the sample A. However, if the distance exceeds twice the Rayleigh length, it gradually becomes impossible to process the sample A with the laser light L. Therefore, the following method can be considered to form a recess CV with a depth that greatly exceeds the Rayleigh length.

[0156] That is, one possible method is to perform scanning with the laser light L while positioning the position of the focal point P of the laser light L in the first direction D1 at a predetermined position between the bottom surface of the recess CV and the surface As of the sample A. Specifically, for example, if the depth of the recess CV formed in step S103 does not greatly exceed the Rayleigh length, in step S105, scanning with the laser light L is performed with the focal point P of the laser light L positioned on the bottom surface of the recess CV formed in step S103. This forms a recess CV with a new bottom surface. Subsequently, in step S107, scanning with the laser light L is performed while fixing the position of the focal point P of the laser light L in the first direction D1 at the same position as in step S105 (i.e., while maintaining it at the position of the bottom surface of the recess CV formed in step S103).

[0157] This makes it possible to proceed with the processing in step S107 while preventing both the distance from the focal point P of the laser light L to the surface As of the sample A and the distance from the focal point P of the laser light L to the bottom surface of the recess CV formed in step S105 from greatly exceeding the Rayleigh length. As a result, it becomes possible to form a recess CV whose depth as a whole greatly exceeds the Rayleigh length while maintaining a good processed cross section.

[0158] That is, as processing proceeds through step S103, step S105, and multiple steps S107, the focal point P is moved toward the bottom of the recess CV up to a certain step, but after a certain step, the focal point P can be fixed so as not to move toward the bottom of the recess CV. One example of a certain step is a step in which recesses CV are formed to a depth half the depth of the final target recess CV (for example, a step in which recesses CV are formed to a depth of 500 μm when the target is to form recesses CV to a depth of 1000 μm). Furthermore, multiple processing steps (for example, multiple steps of step S107) may be performed while the position of the focal point P in the first direction D1 is fixed. [Other variations]

[0159] In the above description, the area of ​​the first scanning range R1 is smaller than or equal to the area of ​​the second scanning range R2. However, the area of ​​the first scanning range R1 may be larger than the area of ​​the second scanning range R2. In this case, it is sufficient that the second scanning range R2 includes a portion of the first scanning range R1 and extends outside the first scanning range R1 on at least one side of the second direction D2. The same applies to the relationship between the third scanning range R3a and the second scanning range R2, and the relationship between the third scanning range R3b and the third scanning range R3a.

[0160] Furthermore, in the laser processing apparatus 20, the setting unit 72 may set the irradiation conditions for each of the multiple scanning sets, for example, by receiving input from a user (via the input receiving unit 71), but it may also set only the irradiation conditions for some of the multiple scanning sets by receiving input, and obtain (for example, calculate) the irradiation conditions for the remaining of the multiple scanning sets based on the irradiation conditions for those some of the scanning sets.

[0161] In this case, for example, the setting unit 72 may acquire the irradiation conditions for a scanning set between the first scanning set and the last scanning set based on the irradiation conditions for the first scanning set and the irradiation conditions for the last scanning set that are set by receiving input. In this case, it is possible to acquire the irradiation conditions for obtaining a good-quality processed cross section Ls in the intermediate scanning set based on the irradiation conditions for the first scanning set and the irradiation conditions for the last scanning set that are set by user input.

[0162] Furthermore, the setting unit 72 may acquire (e.g., calculate) the number of scanning sets and the irradiation conditions for each scanning set based on the opening shape of the target recess CV. In this case, it is possible to acquire the number of scanning sets and the irradiation conditions for each scanning set for obtaining a good quality processed cross section Ls based on the opening shape of the target recess CV.

[0163] Furthermore, in the above explanation, an example was given in which the recess CV does not reach the outer edge of the sample A when viewed from the first direction D1. However, the recess CV may reach the outer edge of the sample A when viewed from the first direction D1, for example, when forming the recess CV by performing processing by scanning the laser light L from the end of the sample A. In this case, an inner surface may not be formed in the portion that reaches the outer edge of the sample A. In other words, the recess CV does not necessarily need to be a space whose periphery is completely surrounded by inner surfaces, but it is sufficient that it has at least a bottom surface and a processed cross section Ls. [Explanation of symbols]

[0164] 2...sample holder (placement section), 4...first microscope section (microscope), 5...second microscope section (microscope), 20...laser processing device, 30...laser output section, 40...laser optical system (laser irradiation section), 41...spatial light modulator, 43...galvanometer mirror (scanning section), 60...laser section, 70...control section, 72...setting section, 73...laser control section, A...sample (object), CV...recess, L...laser light, Ls...processing cross section, P...focus point, R1...first scanning range, R2...second scanning range, R3a, R3b...third scanning range.

Claims

1. A laser processing method for forming a recess in an object by irradiating it with laser light, comprising: a first step of forming the recess in the object by scanning the laser light on the object over a first scanning range along a second direction intersecting a first direction along an optical axis of the laser light and a third direction intersecting the first direction and the second direction; a second step of scanning the object with the laser light over a second scanning range along the second direction and the third direction after the first step; Equipped with the second scanning range includes at least a part of the first scanning range when viewed from the first direction, and extends outside the first scanning range at least in the second direction; In the second step, the recess is enlarged in the first direction and the second direction by scanning the laser light over the second scanning range on the object. Laser processing method.

2. a third step of moving a position of a focal point of the laser light in the first direction toward a bottom surface of the recess after the first step and before the second step, In the second step, the laser beam is scanned in a state where the focal point is aligned with the position moved in the third step. The laser processing method according to claim 1 .

3. a fourth step of observing, after the second step, an inner surface of the recess facing the second direction with a microscope; The laser processing method according to claim 1 .

4. The recess is formed so that an inner surface of the recess facing the second direction is inclined with respect to the first direction. The laser processing method according to claim 1 .

5. the second scanning range, when viewed from the first direction, extends outside the first scanning range in the second direction and the third direction; The laser processing method according to claim 1 .

6. When viewed from the first direction, the second scanning range extends outside the first scanning range only on one side in the second direction. The laser processing method according to claim 1 .

7. a length of a portion of the second scanning range located outside the first scanning range in the second direction is shorter than a length from one end to the other end in the first direction of an inner surface of the recess formed in the first step that faces the second direction; The laser processing method according to claim 1 .

8. In the first step, the laser beam is scanned a plurality of times over the first scanning range. The laser processing method according to claim 1 .

9. In the second step, the laser beam is scanned a plurality of times over the second scanning range; the number of times of scanning with the laser light in the first step is the same as the number of times of scanning with the laser light in the second step; The laser processing method according to claim 8.

10. In the second step, the laser beam is scanned a plurality of times over the second scanning range; the number of times of scanning with the laser light in the first step is different from the number of times of scanning with the laser light in the second step; The laser processing method according to claim 8.

11. The area of ​​the first scanning range is larger than the area of ​​the second scanning range. The laser processing method according to claim 1 .

12. The area of ​​the first scanning range is the same as the area of ​​the second scanning range. The laser processing method according to claim 1 .

13. The area of ​​the first scanning range is smaller than the area of ​​the second scanning range. The laser processing method according to claim 1 .

14. The pulse width of the laser light is 1 ps or less. The laser processing method according to claim 1 .

15. In the second step, an expanded length of the recess in the first direction is greater than an expanded length of the recess in the second direction. The laser processing method according to claim 1 .

16. The magnitude of the irradiation energy of the laser light in the first step is the same as the magnitude of the irradiation energy of the laser light in the second step. The laser processing method according to claim 1 .

17. The magnitude of the irradiation energy of the laser light in the first step is greater than the magnitude of the irradiation energy of the laser light in the second step. The laser processing method according to claim 1 .

18. scanning the laser light modulated by a spatial light modulator onto the object; The laser processing method according to claim 1 .

19. one or more fifth steps of scanning the object with the laser light over a third scanning range along the second direction and the third direction after the second step; the third scanning range includes at least a part of the second scanning range when viewed from the first direction, and extends outside the second scanning range at least in the second direction; In the fifth step, the recess is enlarged in the first direction and the second direction by scanning the laser light over the third scanning range on the object. The laser processing method according to claim 1 .

20. When the fifth step is performed in a plurality of steps, the plurality of fifth steps are performed so that the third scanning range in one of the fifth steps includes at least a part of the third scanning range in another fifth step before the one of the fifth steps when viewed from the first direction, and reaches an outside of the third scanning range in the another fifth step at least in the second direction.

20. The laser processing method according to claim 19.

21. a sixth step of moving a position of a focal point of the laser light in the first direction toward a bottom surface of the recess after the second step and before the fifth step, In the fifth step, the laser beam is scanned in a state where the focal point is aligned with the position moved in the sixth step.

20. The laser processing method according to claim 19.

22. A laser processing device for forming a recess in an object by irradiating it with laser light, a placement unit on which the object is placed; a laser unit including a laser output unit that outputs the laser light and a laser irradiation unit that irradiates the laser light output from the laser output unit onto the object placed in the placement unit; a control unit that controls the laser unit, the laser irradiation unit has a scanning unit for scanning the laser light output from the laser output unit over the object placed in the placement unit, The control unit a first process of controlling the laser unit to form the recess in the object by scanning the laser light on the object over a first scanning range along a second direction intersecting a first direction along an optical axis of the laser light and a third direction intersecting the first direction and the second direction; a second process of controlling the laser unit to scan the object with the laser light over a second scanning range along the second direction and the third direction after the first process; Run the second scanning range includes at least a part of the first scanning range when viewed from the first direction, and extends outside the first scanning range at least in the second direction; the control unit controls the laser unit to enlarge the recess in the first direction and the second direction by scanning the laser light on the object over the second scanning range in the second processing. Laser processing equipment.

23. the laser irradiation unit includes a spatial light modulator for modulating and emitting the laser light output from the laser output unit, the scanning unit scans the laser light emitted from the spatial light modulator onto the object placed on the placement unit; The laser processing device according to claim 22.

24. a placement unit in which an object is placed; a laser unit including a laser output unit that outputs laser light and a laser irradiation unit that irradiates the laser light output from the laser output unit onto the object placed in the placement unit; a control unit that controls the laser unit, the laser irradiation unit includes a spatial light modulator for modulating and emitting the laser light output from the laser output unit, and a scanning unit for scanning the laser light output from the spatial light modulator over the object placed in the placement unit, The control unit a setting unit that receives an input and sets irradiation conditions including a scanning range of the laser light, the number of scans of the laser light across the scanning range, and a position of a focal point of the laser light; a laser control unit that controls the laser unit so as to scan the object with the laser light under the irradiation conditions set by the setting unit; Including, Laser processing equipment.

25. the setting unit has a function of setting a scan set for performing a plurality of scans of the laser light while keeping the irradiation conditions constant. The laser processing apparatus according to claim 24.

26. the setting unit has a function of setting a plurality of the scanning sets, the laser control unit has a function of controlling the laser unit so that, when a plurality of scanning sets are set in the setting unit, the plurality of scanning sets are successively executed. The laser processing apparatus according to claim 25.

27. The number of the scanning sets that can be set by the setting unit is 3 or more.

27. The laser processing apparatus according to claim 26.

28. the setting unit acquires the irradiation conditions of the scanning sets between the first scanning set and the last scanning set based on the irradiation conditions of the first scanning set and the irradiation conditions of the last scanning set that are set by receiving an input.

28. The laser processing apparatus according to claim 27.

29. When a recess is formed in the object by irradiating the laser light, the setting unit acquires the number of the scanning sets and the irradiation conditions for each of the scanning sets based on a target opening shape of the recess.

27. The laser processing apparatus according to claim 26.

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