Laser processing device and laser processing method

Abstract

On a light-emission surface of a light-focusing part of this laser processing device, the optical axis of non-processing light is offset from the optical axis of the light-focusing part toward one side in a first direction, and the optical axis of reflected light is offset from the optical axis of the light-focusing part toward the other side in the first direction. A control unit controls a drive unit such that a line extends in a second direction inclined at an angle of 45-135° with respect to the first direction. On the basis of a detection result from a light detection unit, the control unit controls the drive unit such that the light-focused spot of processing light relatively moves along the line, while controlling the drive unit such that a prescribed surface of an object and the light-focused spot of the processing light have a prescribed distance therebetween.

Description

Laser processing device and laser processing method

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

[0002] A laser processing device is known that includes a support unit that supports an object, a first light source that emits processing light, a second light source that emits non-processing light, a focusing unit that transmits the processing light and the non-processing light toward the object, and a light detection unit that detects reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing unit from the object side (see, for example, Patent Document 1). In such a laser processing device, at the light emission surface of the focusing unit, the optical axis of the non-processing light may be offset to one side from the optical axis of the focusing unit, and the optical axis of the reflected light may be offset to the other side from the optical axis of the focusing unit.

[0003] Japanese Patent Application Laid-Open No. 2019-178923

[0004] In the laser processing device as described above, height information of a specified surface of the object can be acquired, so that the processing position using the processing light can be set on the object based on the specified surface of the object.

[0005] An object of the present disclosure is to provide a laser processing apparatus and a laser processing method that can stably set a processing position by processing light on an object based on a predetermined surface of the object.

[0006] a laser processing device according to one aspect of the present disclosure, including: [1] "a support unit that supports an object; a first light source that emits processing light; a second light source that emits non-processing light; a focusing unit that transmits the processing light and the non-processing light toward the object; a light detection unit that detects reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing unit from the object side; a drive unit that drives at least one of the support unit and the focusing unit; and a control unit that controls at least the drive unit, wherein an optical axis of the non-processing light is offset to one side in a first direction from an optical axis of the focusing unit at a light emission surface of the focusing unit; the optical axis of the reflected light is offset from the optical axis of the focusing unit to the other side in the first direction at the light exit surface, the control unit controls the drive unit so that a line set on the object extends in a second direction inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the first direction, and the control unit controls the drive unit so that the distance between the specified surface and the focusing spot of the processing light located within the object becomes a specified distance based on the detection result by the light detection unit, while controlling the drive unit so that the focusing spot moves relatively along the line.

[0007] In the laser processing apparatus, when the optical axis of the non-processing light is offset from the optical axis of the focusing unit to one side in the first direction and the optical axis of the reflected light is offset from the optical axis of the focusing unit to the other side in the first direction, the drive unit is controlled so that a line set on the object extends in a second direction inclined at an angle of 45 degrees to 135 degrees relative to the first direction. Based on the detection results from the light detection unit, the drive unit is controlled so that the distance between a predetermined surface of the object and a focused spot of the processing light located within the object is a predetermined distance, while the drive unit is controlled so that the focused spot of the processing light moves relatively along the line. Here, when processing the object by irradiating it with processing light, dirt is particularly likely to adhere to the areas around the light exit surface of the focusing unit on both sides of the optical axis of the focusing unit in the second direction (this is a finding discovered by the inventors). In other words, dirt is less likely to adhere to the areas of the light exit surface of the focusing unit through which the non-processing light and reflected light pass. Therefore, even if dirt adheres to the light exit surface of the light collecting unit, height information of the predetermined surface of the object can be obtained. Therefore, with the above laser processing device, the processing position by the processing light can be stably set on the object based on the predetermined surface of the object.

[0008] The laser processing apparatus according to one aspect of the present disclosure may be [2] "the laser processing apparatus according to [1] above, further including a spatial light modulator that modulates the processing light on an optical path from the first light source to the focusing unit, wherein the control unit controls the spatial light modulator so that, when the focused spot of the processing light not modulated by the spatial light modulator is positioned at a processing position within the object and the reflection position of the non-processing light on the predetermined surface is offset to the one side, at least one of a first modulation that moves the focused spot closer to the processing position in a third direction parallel to the optical axis of the focusing unit and a second modulation that moves the focused spot closer to the reflection position in the first direction" [2]. This laser processing apparatus can reduce the "amount of deviation in the first direction" between the position of the focused spot of the processing light (i.e., the processing position within the object) and the reflection position of the non-processing light, thereby enabling the focused spot of the processing light to be accurately positioned on a line at a predetermined distance from the predetermined surface of the object.

[0009] The laser processing device according to one aspect of the present disclosure may be [3] "the laser processing device according to the above [2], in which the control unit determines whether to perform at least one of the first modulation and the second modulation based on the detection result when the focused spot of the processing light that is not modulated by the first modulation and the second modulation is positioned at the processing position." This laser processing device can prevent the reflection position of the non-processing light from being located on a member due to an increase in the "amount of deviation in the first direction" between the position of the focused spot of the processing light and the reflection position of the non-processing light.

[0010] The laser processing device according to one aspect of the present disclosure may be [4] "the laser processing device described in [3] above, wherein the control unit determines whether to perform at least one of the first modulation and the second modulation by comparing the detection result when the focused spot of the processing light not modulated by the first modulation and the second modulation is positioned on the predetermined plane with the detection result when the focused spot of the processing light not modulated by the first modulation and the second modulation is positioned at the processing position." This laser processing device can reliably determine whether the reflection position of the non-processing light is located on a member when the focused spot of the processing light is positioned at the processing position within the object, thereby reliably preventing the reflection position of the non-processing light from being located on a member.

[0011] The laser processing device according to one aspect of the present disclosure may be [5] "the laser processing device according to [3] or [4] above, wherein the object is a wafer including a plurality of functional elements arranged two-dimensionally along the predetermined plane, the line is set on the wafer so as to pass between adjacent functional elements among the plurality of functional elements, and the detection result when the focused spot of the processing light not modulated by the first modulation and the second modulation is positioned at the processing position is acquired between the adjacent functional elements." With this laser processing device, it is possible to reliably determine whether the reflection position of the non-processing light is located on a functional element when the focused spot of the processing light is positioned at the processing position within the object, thereby reliably preventing the reflection position of the non-processing light from being located on a functional element.

[0012] A laser processing method according to one aspect of the present disclosure includes [6] "a support unit that supports an object, a first light source that emits processing light, a second light source that emits non-processing light, a focusing unit that transmits the processing light and the non-processing light toward the object, a light detection unit that detects reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing unit from the object side, and a drive unit that drives at least one of the support unit and the focusing unit, wherein the optical axis of the non-processing light is offset from the optical axis of the focusing unit to one side in a first direction on a light emission surface of the focusing unit, and the optical axis of the reflected light is offset from the optical axis of the focusing unit to the other side in the first direction on the light emission surface. a laser processing method to be carried out in a laser processing device that is offset, the laser processing method comprising: a first step of driving at least one of the support part and the focusing part with the driving part so that a line set on the object extends in a second direction inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the first direction; and a second step of driving at least one of the support part and the focusing part with the driving part so that the focusing spot moves relatively along the line while controlling the driving part so that the distance between the predetermined surface and the focusing spot of the processing light located within the object becomes a predetermined distance based on the detection result by the light detection part.

[0013] According to the above laser processing method, for the same reason as in the above laser processing apparatus, the processing position by the processing light can be stably set on the object with reference to a predetermined surface of the object.

[0014] According to the present disclosure, it is possible to provide a laser processing device and a laser processing method that can stably set the processing position by processing light on an object based on a predetermined surface of the object.

[0015] FIG. 1 is a perspective view of a laser processing apparatus according to an embodiment. FIG. 2 is a front view of a portion of the laser processing apparatus shown in FIG. 1. FIG. 3 is a front view of a laser processing head shown in FIG. 1. FIG. 4 is a side view of the laser processing head shown in FIG. 1. FIG. 5 is a configuration diagram of the laser processing head shown in FIG. 4. FIG. 6 is a configuration diagram of a distance measuring unit shown in FIG. 5. FIG. 7 is a configuration diagram of a portion of the distance measuring unit shown in FIG. 6. FIG. 8 is a diagram showing optical paths of distance measuring light and reflected light in the distance measuring unit shown in FIG. 6. FIG. 9 is a schematic diagram of a light exit surface of a focusing unit shown in FIG. 5. FIG. 10 is a schematic diagram showing how an object is processed by irradiating it with laser light. FIG. 11 is a schematic diagram for explaining the premise of control related to first modulation and second modulation. FIG. 12 is a schematic diagram for explaining control related to first modulation. FIG. 13 is a schematic diagram for explaining control related to second modulation. FIG. 14 is a schematic diagram for explaining control related to first modulation and second modulation. Fig. 15 is a flowchart for explaining control relating to the first modulation and the second modulation. Fig. 16 is a schematic diagram relating to the flowchart shown in Fig. 15. Fig. 17 is a schematic diagram relating to the flowchart shown in Fig. 15. Fig. 18 is a schematic diagram relating to the flowchart shown in Fig. 15. Fig. 19 is a schematic diagram of the light exit surface of the light collecting unit shown in Fig. 5.

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted. [Configuration of laser processing device]

[0017] 1, the laser processing apparatus 1 includes a plurality of movement mechanisms (drive units) 5 and 6, a support unit 7, a pair of laser processing heads 10A and 10B, a light source unit 8, and a control unit 9. Hereinafter, the three mutually perpendicular directions will be referred to as the X direction, the Y direction, and the Z direction. In this embodiment, the Z direction is the vertical direction, and the X direction and the Y direction are horizontal directions.

[0018] The movement mechanism 5 has a fixed part 51, a moving part 53, and an attachment part 55. The fixed part 51 is attached to the device frame 1a. The moving part 53 is attached to a rail provided on the fixed part 51 and can move along the X direction. The attachment part 55 is attached to a rail provided on the moving part 53 and can move along the Y direction.

[0019] The movement mechanism 6 has a fixed part 61, a pair of moving parts 63 and 64, and a pair of mounting parts 65 and 66. The fixed part 61 is attached to the device frame 1a. Each of the pair of moving parts 63 and 64 is attached to a rail provided on the fixed part 61, and each can move independently along the X direction. The mounting part 65 is attached to a rail provided on the moving part 63, and can move along the Z direction. The mounting part 66 is attached to a rail provided on the moving part 64, and can move along the Z direction.

[0020] The support unit 7 is attached to a rotation shaft provided on the mounting unit 55 of the movement mechanism 5, and can rotate about an axis parallel to the Z direction. The support unit 7 supports the object W. The object W is, for example, a wafer.

[0021] 1 and 2 , the laser processing head 10A is attached to the attachment portion 65 of the moving mechanism 6. The laser processing head 10A faces the support portion 7 in the Z direction and irradiates the object W supported by the support portion 7 with laser light (processing light) L. The laser processing head 10B is attached to the attachment portion 66 of the moving mechanism 6. The laser processing head 10B faces the support portion 7 in the Z direction and irradiates the object W supported by the support portion 7 with laser light L.

[0022] 1, the light source unit 8 has a pair of light sources (first light sources) 81, 82. The pair of light sources 81, 82 are attached to the device frame 1a. Each of the pair of light sources 81, 82 emits a laser beam L. The laser beam L emitted from the emission portion 81a of the light source 81 is guided to the laser processing head 10A by an optical fiber 2. The laser beam L emitted from the emission portion 82a of the light source 82 is guided to the laser processing head 10B by another optical fiber 2.

[0023] The control unit 9 controls each part of the laser processing apparatus 1 (such as the multiple movement mechanisms 5 and 6, the pair of laser processing heads 10A and 10B, and the light source unit 8). The control unit 9 is configured as a computer device including a processor, memory, storage, and communication devices. In the control unit 9, software (programs) loaded into the memory, etc., is executed by the processor, and the processor controls the reading and writing of data in the memory and storage, as well as communication via the communication devices. In this way, the control unit 9 realizes various functions. The control unit 9 has a display 91. The display 91 displays various information. The display 91 may be configured as a touch panel that accepts instructions input by the operator.

[0024] The laser processing apparatus 1 configured as described above can be used for various purposes, such as dicing to divide a wafer, slicing to thin a wafer, and trimming to remove the outer periphery of a wafer. Here, an example of processing using the laser processing apparatus 1 will be described. This example of processing is an example of forming modified regions inside an object W, which is a wafer, along each of a plurality of lines set in a grid pattern in order to cut the object W into a plurality of chips (i.e., an example of the first half of a dicing process).

[0025] First, with the support part 7 supporting the object W, the movement mechanism 5 moves the support part 7 along both the X direction and the Y direction so that the laser processing head 10A faces the support part 7, and the movement mechanism 6 moves the laser processing head 10A along the X direction. Next, the movement mechanism 5 rotates the support part 7 about an axis parallel to the Z direction so that multiple lines extending in one direction on the object W are aligned along the X direction.

[0026] Next, the movement mechanism 5 moves the support part 7 along the Y direction so that the focused spot of the laser light L emitted from the laser processing head 10A (hereinafter referred to as "laser light L of the laser processing head 10A") is positioned on a line extending in one direction. Next, the movement mechanism 6 moves the laser processing head 10A along the Z direction so that the focused spot of the laser light L of the laser processing head 10A is positioned inside the target object W.

[0027] Next, the light source 81 emits laser light L, and the laser processing head 10A irradiates the object W with the laser light L. At the same time, the movement mechanism 6 moves the laser processing head 10A along the X direction so that the focused spot of the laser light L of the laser processing head 10A moves relatively along a line extending in one direction. In this way, the laser processing apparatus 1 forms modified regions inside the object W along each of a plurality of lines extending in one direction on the object W.

[0028] Next, the moving mechanism 5 rotates the support part 7 about an axis parallel to the Z direction so that a plurality of lines extending in another direction perpendicular to the one direction on the object W are aligned along the X direction.

[0029] Next, the movement mechanism 5 moves the support part 7 along the Y direction so that the focused spot of the laser light L of the laser processing head 10A is positioned on a line extending in the other direction. Next, the movement mechanism 6 moves the laser processing head 10A along the Z direction so that the focused spot of the laser light L of the laser processing head 10A is positioned inside the target object W.

[0030] Next, the light source 81 emits laser light L, and the laser processing head 10A irradiates the object W with the laser light L. At the same time, the movement mechanism 6 moves the laser processing head 10A along the X direction so that the focused spot of the laser light L of the laser processing head 10A moves relatively along one line extending in the other direction. In this way, the laser processing apparatus 1 forms modified regions inside the object W along each of a plurality of lines extending in the other direction perpendicular to the one direction on the object W.

[0031] In one example of the above processing, the light source 81 emits laser light L that is transparent to the object W, for example, by a pulse oscillation method. When such laser light L is focused inside the object W, the laser light L is particularly absorbed in the portion corresponding to the focused spot of the laser light L, forming a modified region inside the object W. The modified region is a region whose density, refractive index, mechanical strength, and other physical properties differ from those of the surrounding unmodified region. Examples of modified regions include a melt-treated region, a crack region, a dielectric breakdown region, and a refractive index change region.

[0032] When the laser light L emitted by the pulse oscillation method is irradiated onto the object W and the focused spot of the laser light L is moved relatively along a line set on the object W, multiple modified spots are formed lined up in a row along the line. One modified spot is formed by irradiating one pulse of laser light L. A row of modified regions is a collection of multiple modified spots lined up in a row. Adjacent modified spots may be connected to each other or separated from each other depending on the relative moving speed of the focused spot of the laser light L with respect to the object W and the repetition frequency of the laser light L.

[0033] In the above example of processing, the laser processing head 10A was used to form the modified region, but the laser processing head 10B may also be used to form the modified region. When the laser processing head 10B is used, the modified region can be formed inside the object W by the same operation as when the laser processing head 10A is used. In the laser processing device 1, the laser processing head 10A and the laser processing head 10B are aligned in the X direction. Therefore, when forming multiple rows of modified regions aligned in the thickness direction along a single line, by moving the laser processing head 10A and the laser processing head 10B relative to each other along the line once, some modified regions can be formed by the laser processing head 10A, while other modified regions different from the some modified regions can be formed by the laser processing head 10B. [Configuration of the laser processing head]

[0034] As shown in FIGS. 2, 3, and 4, the laser processing head 10A includes a housing 11, an incident portion 12, a laser beam adjusting portion 13, and a focusing portion 14.

[0035] The housing 11 has a first wall portion 21 and a second wall portion 22, a third wall portion 23 and a fourth wall portion 24, and a fifth wall portion 25 and a sixth wall portion 26. The first wall portion 21 and the second wall portion 22 face each other in the Y direction. The third wall portion 23 and the fourth wall portion 24 face each other in the X direction. The fifth wall portion 25 and the sixth wall portion 26 face each other in the Z direction.

[0036] The distance between the third wall portion 23 and the fourth wall portion 24 is smaller than the distance between the first wall portion 21 and the second wall portion 22. The distance between the first wall portion 21 and the second wall portion 22 is smaller than the distance between the fifth wall portion 25 and the sixth wall portion 26. The distance between the first wall portion 21 and the second wall portion 22 may be equal to the distance between the fifth wall portion 25 and the sixth wall portion 26, or may be larger than the distance between the fifth wall portion 25 and the sixth wall portion 26.

[0037] In the laser processing head 10A, the first wall 21 is located on the opposite side from the fixed portion 61 of the moving mechanism 6, and the second wall 22 is located on the fixed portion 61 side. The third wall 23 is located on the mounting portion 65 side of the moving mechanism 6, and the fourth wall 24 is located on the laser processing head 10B side opposite the mounting portion 65. The fifth wall 25 is located on the opposite side from the support portion 7, and the sixth wall 26 is located on the support portion 7 side.

[0038] The housing 11 is configured so that the housing 11 is attached to the mounting portion 65 with the third wall portion 23 positioned on the mounting portion 65 side of the movement mechanism 6. Specifically, the mounting portion 65 has a base plate 65a and a mounting plate 65b. The base plate 65a is attached to a rail provided on the movement portion 63. The mounting plate 65b is erected at the end of the base plate 65a on the laser processing head 10B side. The housing 11 is attached to the mounting portion 65 by threading the bolts 28 into the mounting plate 65b via the pedestals 27 with the third wall portion 23 in contact with the mounting plate 65b. The pedestals 27 are provided on both the first wall portion 21 and the second wall portion 22. The housing 11 is detachable from the mounting portion 65.

[0039] The incident portion 12 is disposed on the fifth wall portion 25. The incident portion 12 causes the laser light L to enter the housing 11. The incident portion 12 is biased toward the first wall portion 21 in the Y direction and toward the fourth wall portion 24 in the X direction. In other words, the distance between the incident portion 12 and the first wall portion 21 in the Y direction is smaller than the distance between the incident portion 12 and the second wall portion 22 in the Y direction, and the distance between the incident portion 12 and the fourth wall portion 24 in the X direction is smaller than the distance between the incident portion 12 and the third wall portion 23 in the X direction.

[0040] The incident portion 12 is connected to the output end 2a of the optical fiber 2. Specifically, the incident portion 12 is a portion including a hole 25a formed in the fifth wall portion 25. The fifth wall portion 25 is provided with an attachment portion 25b. The main body portion 2b of the output end 2a is attached to the attachment portion 25b with a bolt or the like. In this state, the tip portion 2c of the output end 2a passes through the hole 25a. This makes the output end 2a of the optical fiber 2 detachable from the incident portion 12. A cover 25c is disposed between the fifth wall portion 25 and the main body portion 2b. The cover 25c covers the gap formed between the hole 25a and the tip portion 2c. As an example, at the output end 2a, an isolator that suppresses returning light is disposed in the main body portion 2b, and a collimator lens that collimates the laser light L is disposed in the tip portion 2c. The incident portion 12 may be a connector or the like configured to be connectable to the output end 2a of the optical fiber 2.

[0041] The laser beam adjustment unit 13 is disposed within the housing 11. The laser beam adjustment unit 13 adjusts the laser beam L incident from the incident unit 12. The laser beam adjustment unit 13 is disposed within the housing 11 on the fourth wall 24 side with respect to the partition wall 29. The laser beam adjustment unit 13 is attached to the partition wall 29. The partition wall 29 is provided within the housing 11 and divides the area within the housing 11 into an area on the third wall 23 side and an area on the fourth wall 24 side. The partition wall 29 is configured as a part of the housing 11. Each component of the laser beam adjustment unit 13 is attached to the partition wall 29 on the fourth wall 24 side. The partition wall 29 functions as an optical base that supports each component of the laser beam adjustment unit 13.

[0042] The light condensing unit 14 is disposed on the sixth wall 26. Specifically, the light condensing unit 14 is disposed on the sixth wall 26, passing through a hole 26a (see FIG. 5 ) formed in the sixth wall 26. The light condensing unit 14 condenses the laser light L adjusted by the laser beam adjusting unit 13 and emits the laser light L to the outside of the housing 11. The light condensing unit 14 is biased toward the second wall 22 in the Y direction and toward the fourth wall 24 in the X direction. In other words, the distance between the light condensing unit 14 and the second wall 22 in the Y direction is smaller than the distance between the light condensing unit 14 and the first wall 21 in the Y direction, and the distance between the light condensing unit 14 and the fourth wall 24 in the X direction is smaller than the distance between the light condensing unit 14 and the third wall 23 in the X direction.

[0043] As shown in FIG. 5 , the laser beam adjusting unit 13 includes a reflecting unit 31, an attenuator 32, and a reflecting unit 33. The reflecting unit 31, the attenuator 32, and the reflecting unit 33 are arranged on a first straight line SL1 extending along the Y direction. The reflecting unit 31 faces the incident unit 12 in the Z direction. That is, the reflecting unit 31 faces the output end 2a of the optical fiber 2 in the Z direction. The reflecting unit 31 reflects the laser beam L incident from the incident unit 12 toward the second wall unit 22. The attenuator 32 adjusts the output of the laser beam L reflected by the reflecting unit 31. The reflecting unit 33 reflects the laser beam L, the output of which has been adjusted by the attenuator 32, toward the sixth wall unit 26. Each of the reflecting units 31 and 33 is, for example, a mirror or a prism.

[0044] The laser light adjusting unit 13 further includes a beam expander 34 and a reflecting unit 35. The reflecting unit 33, the beam expander 34, and the reflecting unit 35 are arranged on a second straight line SL2 extending along the Z direction. The beam expander 34 expands the diameter of the laser light L reflected by the reflecting unit 33. The reflecting unit 35 reflects the laser light L, the diameter of which has been expanded by the beam expander 34, toward the first wall unit 21 and the fifth wall unit 25. The reflecting unit 35 is, for example, a mirror or a prism.

[0045] The laser beam adjusting unit 13 further includes a spatial light modulator 36 and an imaging optical system 37. The spatial light modulator 36, the imaging optical system 37, and the focusing unit 14 are arranged on a third straight line SL3 extending along the Z direction. The spatial light modulator 36 modulates the laser beam L reflected by the reflecting unit 35 and reflects it toward the sixth wall unit 26. That is, the spatial light modulator 36 modulates the laser beam L on the optical path of the laser beam L from the light source 81 to the focusing unit 14. The spatial light modulator 36 is a reflective spatial light modulator. The spatial light modulator 36 is, for example, an LCOS (Liquid Crystal on Silicon)-SLM (Spatial Light Modulator). The imaging optical system 37 forms a double-telecentric optical system in which the reflecting surface 36a of the spatial light modulator 36 and the entrance pupil plane 14a of the focusing unit 14 are in an imaging relationship. The imaging optical system 37 is composed of multiple lenses.

[0046] The first line SL1, the second line SL2, and the third line SL3 are located on the same plane perpendicular to the X direction. The second line SL2 is located on the second wall portion 22 side of the third line SL3. In the laser processing head 10A, the laser light L incident on the entrance portion 12 into the housing 11 along the Z direction is reflected by the reflecting portion 31 and travels along the first line SL1. The laser light L traveling along the first line SL1 is reflected by the reflecting portion 33 and travels along the second line SL2. The laser light L traveling along the second line SL2 is sequentially reflected by the reflecting portion 35 and the spatial light modulator 36 and travels along the third line SL3. The laser light L traveling along the third line SL3 is emitted from the focusing portion 14 to the outside of the housing 11 along the Z direction.

[0047] The laser processing head 10A further includes a dichroic mirror 15, an observation unit 16, a distance measurement unit 100, a drive unit 18, and a circuit unit 19. In this embodiment, the circuit unit 19 constitutes a part of the control unit 9.

[0048] The dichroic mirror 15 is disposed on the third straight line SL3 between the imaging optical system 37 and the condenser 14. That is, the dichroic mirror 15 is disposed within the housing 11 between the laser light adjustment unit 13 and the condenser 14. The dichroic mirror 15 is attached to the partition wall 29 on the side of the fourth wall 24. The dichroic mirror 15 transmits the laser light L. From the viewpoint of suppressing astigmatism, the dichroic mirror 15 is preferably, for example, a cube type or a type of two plates arranged to have a twisted relationship.

[0049] The observation unit 16 is disposed within the housing 11 on the first wall 21 side with respect to the third straight line SL3. That is, the observation unit 16 is disposed on the first wall 21 side with respect to the light collecting unit 14 in the Y direction. The observation unit 16 is attached to the partition wall 29 on the fourth wall 24 side. The observation unit 16 irradiates the surface of the object W with observation light L10 (e.g., visible light) for observing the surface of the object W (e.g., the surface on the side where the laser light L is incident), and detects the observation light L10 reflected by the surface of the object W.

[0050] In this embodiment, the observation light L10 emitted from the observation unit 16 is reflected successively by the beam splitter 20 and the dichroic mirror 15, passes through the condenser 14, exits the housing 11, and is irradiated onto the surface of the object W. The observation light L10 reflected by the surface of the object W passes through the condenser 14, enters the housing 11, is reflected successively by the dichroic mirror 15 and the beam splitter 20, and enters the observation unit 16. The beam splitter 20 is attached to the partition wall 29 on the fourth wall 24 side.

[0051] The distance measuring unit 100 is disposed within the housing 11 on the first wall 21 side with respect to the third straight line SL3. That is, the distance measuring unit 100 is disposed on the first wall 21 side with respect to the light collecting unit 14 in the Y direction. The distance measuring unit 100 is attached to the partition wall 29 on the fourth wall 24 side. The distance measuring unit 100 irradiates the surface of the object W with distance measuring light L20 (e.g., laser light) to measure the distance between the surface of the object W (e.g., the surface on the side where the laser light L is incident) and the light collecting unit 14, and detects the distance measuring light L20 reflected by the surface of the object W.

[0052] In this embodiment, the distance measurement light L20 emitted from the distance measurement unit 100 passes through the beam splitter 20, is reflected by the dichroic mirror 15, passes through the light collecting unit 14, is emitted outside the housing 11, and is irradiated onto the surface of the object W. The distance measurement light L20 reflected by the surface of the object W passes through the light collecting unit 14 and enters the housing 11, is reflected by the dichroic mirror 15, passes through the beam splitter 20, and is incident on the distance measurement unit 100. Note that the wavelengths of the laser light L, the distance measurement light L20, and the observation light L10 are different from one another (at least their respective center wavelengths are shifted from one another).

[0053] The drive unit 18 is attached to the partition wall 29 on the side of the fourth wall 24. The drive unit 18 moves the light collecting unit 14 arranged on the sixth wall 26 in the Z direction by, for example, the driving force of a piezoelectric element.

[0054] As shown in FIGS. 3 and 5 , the circuit unit 19 is disposed within the housing 11 on the third wall 23 side relative to the partition wall 29. That is, the circuit unit 19 is disposed within the housing 11 on the third wall 23 side relative to the laser light adjustment unit 13, the distance measurement unit 100, and the observation unit 16. The circuit unit 19 is spaced apart from the partition wall 29. The circuit unit 19 may be, for example, a plurality of circuit boards. The circuit unit 19 processes signals output from the distance measurement unit 100 and signals input to the spatial light modulator 36. The circuit unit 19 controls the drive unit 18 based on the signals output from the distance measurement unit 100. As an example, the circuit unit 19 controls the drive unit 18 based on the signals output from the distance measurement unit 100 so that the distance between the surface of the object W and the focusing unit 14 is maintained constant (i.e., so that the distance between the surface of the object W and the focusing spot of the laser light L is maintained constant).

[0055] The partition wall 29 is formed with notches, holes, etc. (not shown) through which wires pass for electrically connecting the observation unit 16, the distance measurement unit 100, the drive unit 18, and the spatial light modulator 36 to the circuit unit 19. The housing 11 is also provided with a connector (not shown) to which wires, etc. are connected for electrically connecting the circuit unit 19 to the control unit 9. In this embodiment, the circuit unit 19 functions as part of the control unit 9 by electrically connecting the circuit unit 19 to the control unit 9.

[0056] Like the laser processing head 10A, the laser processing head 10B includes a housing 11, an incident section 12, a laser light adjustment section 13, a focusing section 14, a dichroic mirror 15, an observation section 16, a distance measurement section 100, a drive section 18, and a circuit section 19. However, as shown in Fig. 2, the components of the laser processing head 10B are arranged so as to have a plane-symmetric relationship with the components of the laser processing head 10A with respect to an imaginary plane that passes through the midpoint between the pair of mounting sections 65, 66 and is perpendicular to the X direction.

[0057] For example, the housing 11 of the laser processing head 10A is attached to the mounting portion 65 so that the fourth wall portion 24 is located on the laser processing head 10B side relative to the third wall portion 23 and the sixth wall portion 26 is located on the support portion 7 side relative to the fifth wall portion 25. In contrast, the housing 11 of the laser processing head 10B is attached to the mounting portion 66 so that the fourth wall portion 24 is located on the laser processing head 10A side relative to the third wall portion 23 and the sixth wall portion 26 is located on the support portion 7 side relative to the fifth wall portion 25.

[0058] The housing 11 of the laser processing head 10B is configured so that the housing 11 is attached to the attachment portion 66 with the third wall portion 23 positioned on the attachment portion 66 side. Specifically, it is as follows. The attachment portion 66 has a base plate 66a and an attachment plate 66b. The base plate 66a is attached to a rail provided on the moving portion 63. The attachment plate 66b is erected at the end of the base plate 66a on the laser processing head 10A side. The housing 11 of the laser processing head 10B is attached to the attachment portion 66 with the third wall portion 23 in contact with the attachment plate 66b. The housing 11 of the laser processing head 10B is detachable from the attachment portion 66. [Configuration of the Distance Metering Unit]

[0059] As shown in FIG. 6 , the distance measurement unit 100 includes a light source (second light source) 101, a collimating lens 102, a half mirror 103, an imaging lens 105, a reflective grating 106, and a light detection unit 107. Hereinafter, the distance measurement light L20 (see FIG. 5 ) emitted from the distance measurement unit 100 will be referred to as "distance measurement light L21," and the reflected light of the distance measurement light L20 (see FIG. 5 ) reflected by the surface (predetermined surface) Wa of the object W will be referred to as "reflected light L22." Note that FIG. 6 shows each component diagrammatically. For example, the light-collecting unit 14 actually includes multiple lenses and a lens barrel, but is shown as a single lens in FIG. 6 . This also applies to FIGS. 7 and 8 , which will be described later. Also, FIG. 6 omits the illustration of the beam splitter 20 disposed between the distance measurement unit 100 and the dichroic mirror 15.

[0060] The light source 101 emits distance measurement light (unprocessed light) L21. As an example, the light source 101 is a laser diode, and the distance measurement light L21 is laser light. In this embodiment, the light source 101 emits the distance measurement light L21 downward along the Z direction. The collimating lens 102 collimates the distance measurement light L21 emitted from the light source 101.

[0061] The half mirror 103 reflects the distance measurement light L21 collimated by the collimator lens 102 toward the dichroic mirror 15, and transmits the reflected light L22 incident from the dichroic mirror 15 toward the imaging lens 105. In this embodiment, the half mirror 103 reflects the distance measurement light L21 incident from above along the Z direction to one side along the Y direction, and transmits the reflected light L22 from one side to the other side along the Y direction.

[0062] The dichroic mirror 15 reflects the distance measurement light L21 reflected by the half mirror 103 toward the light collecting unit 14, and reflects the reflected light L22 incident from the light collecting unit 14 toward the half mirror 103. In this embodiment, the dichroic mirror 15 reflects the distance measurement light L21 incident from the other side along the Y direction toward the lower side along the Z direction, and reflects the reflected light L22 incident from the lower side along the Z direction toward the other side along the Y direction.

[0063] The focusing unit 14 focuses the distance measurement light L21 reflected by the dichroic mirror 15 and transmits it toward the object W, and transmits reflected light L22 reflected by the surface Wa of the object W toward the dichroic mirror 15. In this embodiment, the focusing unit 14 transmits the distance measurement light L21 from above to below along the Z direction and transmits the reflected light L22 from below to above along the Z direction. The focusing unit 14 transmits the laser light L and the distance measurement light L21 toward the object W.

[0064] The imaging lens 105 transmits the reflected light L22, which has been reflected by the dichroic mirror 15 and transmitted through the half mirror 103, toward the reflective grating 106. In this embodiment, the imaging lens 105 transmits the reflected light L22 from one side to the other along the Y direction. The imaging lens 105 forms an image at the focusing position of the distance measurement light L21 or the reflected light L22 by the focusing unit 14 at the focusing position. If the surface Wa of the object W is located on the opposite side of the focusing unit 14 from the focusing spot when the distance measurement light L21 is focused in air by the focusing unit 14, the focusing position appears in the distance measurement light L21. If the surface Wa of the object W is located on the focusing spot when the distance measurement light L21 is focused in air by the focusing unit 14, the focusing position appears at the boundary between the distance measurement light L21 and the reflected light L22. When the distance measurement light L21 is focused in the air by the focusing unit 14, if the surface Wa of the object W is located on the side of the focusing unit 14 relative to the focusing spot, the focusing position appears in the reflected light L22. The imaging lens 105 may be composed of one lens or multiple lenses.

[0065] The reflective grating 106 reflects the reflected light L22 that has passed through the imaging lens 105 toward the photodetector 107. The reflective grating 106 is, for example, a blazed grating. In this embodiment, the reflective grating 106 reflects the reflected light L22 that has entered from one side along the Y direction toward the upward direction along the Z direction. The reflective grating 106 adjusts the optical path of the reflected light L22 between the imaging lens 105 and the photodetector 107 (details will be described later).

[0066] The light detection unit 107 detects the reflected light L22 reflected by the reflective grating 106. That is, the light detection unit 107 detects the reflected light L22 reflected by the surface Wa of the object W and transmitted through the light collecting unit 14 from the object W side. The light detection unit 107 is, for example, a one-dimensional photodiode array having multiple light detection channels arranged along the Y direction. The light receiving surface 107a of the light detection unit 107 faces the reflective grating 106 and is located on a plane S. In this embodiment, the light receiving surface 107a faces downward and is located on a plane S perpendicular to the Z direction. Note that the light detection unit 107 may be a two-dimensional photodiode array or the like as long as it has multiple light detection channels arranged along the Y direction.

[0067] 7, the light collecting unit 14 transmits the distance measurement light L21 toward the object W in a state in which the optical axis A1 of the distance measurement light L21 is offset from the optical axis A of the light collecting unit 14 (i.e., in a state in which the optical axis A1 is separated from the optical axis A). The optical axis A1 of the distance measurement light L21 incident on the light collecting unit 14 is parallel to the optical axis A of the light collecting unit 14. The optical axis A1 of the distance measurement light L21 emitted from the light collecting unit 14 is inclined so that the focused spot C of the distance measurement light L21 focused by the light collecting unit 14 is located on the optical axis A of the light collecting unit 14. Here, the optical axis A1 of the distance measurement light L21 incident on the light collecting unit 14 is offset to one side in the Y direction (first direction) from the optical axis A of the light collecting unit 14.

[0068] 6 and 7 , the optical path of the reflected light L22 passing through the light collecting unit 14 changes depending on the height of the surface Wa of the object W, and as a result, the incident position of the reflected light L22 on the light receiving surface 107a of the light detecting unit 107 changes depending on the height of the surface Wa of the object W. Therefore, the height of the surface Wa of the object W can be measured based on the incident position of the reflected light L22 on the light receiving surface 107a of the light detecting unit 107 (i.e., based on the position of the light detection channel onto which the reflected light L22 is incident). Note that the height of the surface Wa of the object W refers to the position of the surface Wa of the object W in a direction parallel to the optical axis A of the light collecting unit 14 (here, the Z direction), and corresponds to, for example, the distance between the light collecting unit 14 and the surface Wa of the object W.

[0069] As an example, when the surface Wa of the object W coincides with the focusing spot C of the distance measurement light L21 (the focusing spot when the distance measurement light L21 is focused in the air by the focusing unit 14), the reflected light L22 Ｌ The optical path of the reflected light L22 is symmetrical to the optical path of the distance measurement light L21 with respect to the optical axis A of the light collecting unit 14. When the surface Wa of the object W is located closer to the light collecting unit 14 than the light collecting spot C of the distance measurement light L21, Ｍ The optical path of the reflected light L22 Ｌ When the surface Wa of the object W is located closer to the light condensing unit 14 than the condensing spot C of the distance measuring light L21, the reflected light L22 Ｈ The optical path of the reflected light L22 Ｍ The reflected light is reflected on one side in the Y direction.

[0070] 7, the convergence and divergence state of the reflected light L22 also changes depending on the height of the surface Wa of the object W, and therefore the imaging position of the reflected light L22 by the imaging lens 105 also changes depending on the height of the surface Wa of the object W. Therefore, unless the reflective grating 106 that adjusts the optical path of the reflected light L22 is provided in the distance measuring unit 100, the spot size of the reflected light L22 on the light receiving surface 107a of the light detecting unit 107 will change significantly depending on the height of the surface Wa of the object W, and as a result, there is a risk that the measurement accuracy of the height of the surface Wa of the object W will deteriorate. Furthermore, even if the light receiving surface 107a of the light detection unit 107 is tilted to match the imaging position of the reflected light L22 by the imaging lens 105, the angle of incidence of the reflected light L22 on the light receiving surface 107a will become large, causing part of the reflected light L22 to be reflected by the light receiving surface 107a or increasing the spot size of the reflected light L22 on the light receiving surface 107a, which may result in a deterioration in the measurement accuracy of the height of the surface Wa of the object W.

[0071] For example, if the focal length of the light collecting unit 14 is f1, the focal length of the imaging lens 105 is f2, the difference in height of the surface Wa of the object W in a direction parallel to the optical axis A of the light collecting unit 14 is ΔZ, and the difference in the imaging position of the reflected light L22 in a direction parallel to the optical axis of the imaging lens 105 is ΔY, then if the reflective grating 106 is not provided in the distance measuring unit 100, then ΔY / ΔZ=4(f2 / f1). ２ The following relationship holds. In other words, as the focal length f1 of the light-collecting unit 14 decreases, the difference ΔY in the imaging position of the reflected light L22 increases, and the spot size of the reflected light L22 on the light-receiving surface 107a increases. As described above, when a modified region is formed inside the target object W, the numerical aperture of the light-collecting unit 14 increases and the focal length f1 of the light-collecting unit 14 decreases, so it is particularly important to implement measures to prevent a deterioration in the measurement accuracy of the height of the surface Wa of the target object W.

[0072] 6, a reflective grating 106 that adjusts the optical path of the reflected light L22 is provided in the distance measuring unit 100. The reflective grating 106 adjusts the optical path of the reflected light L22 by generating an optical path length in the reflected light L22 that corresponds to the incident position of the reflected light L22 on the reflective grating 106.

[0073] Furthermore, the optical path of the reflected light L22 that has passed through the imaging lens 105 (the optical path of the chief ray of the reflected light L22) changes along a predetermined plane (here, a plane perpendicular to the X direction) depending on the height of the surface Wa of the object W. Therefore, the reflective grating 106 is arranged so that the multiple grooves extend along a direction perpendicular to the predetermined plane (here, the X direction). Furthermore, the reflective grating 106 is arranged so that the reflected light L22 having a longer optical path length from the imaging lens 105 to the imaging position is reflected by the reflective grating 106 at a position farther from the imaging lens 105.

[0074] As a result, the longer the optical path length of the reflected light L22 from the imaging lens 105 to the imaging position, the longer the optical path length of the reflected light L22 from the imaging lens 105 to the light receiving surface 107a of the light detection unit 107. For example, ＭThe optical path length of the reflected light L22 from the imaging lens 105 to the light receiving surface 107a of the light detection unit 107 is Ｌ The optical path length of the reflected light L22 reaching the light receiving surface 107a of the light detection unit 107 from the imaging lens 105 is longer than the optical path length of the reflected light L22. Ｈ The optical path length of the reflected light L22 from the imaging lens 105 to the light receiving surface 107a of the light detection unit 107 is Ｍ longer than the optical path length of

[0075] However, astigmatism occurs in the reflected light L22 that is imaged by the imaging lens 105 and reflected by the reflective grating 106. Specifically, the image position of the reflected light L22 that is imaged in the X direction is farther from the plane S on which the light-receiving surface 107a of the light detection unit 107 is located than the image position of the reflected light L22 that is imaged in the Y direction. In the distance measurement unit 100, the reflective grating 106 adjusts the optical path of the reflected light L22 so that the image position of the reflected light L22 that is imaged in the Y direction approaches the plane S on which the light-receiving surface 107a of the light detection unit 107 is located.

[0076] In this way, the reflective grating 106 adjusts the optical path of the reflected light L22 so that the imaging position of the reflected light L22, which is formed in at least one direction (here, the Y direction) perpendicular to the incident direction (here, the Z direction) of the reflected light L22 incident on the photodetector 107, approaches a plane S perpendicular to the incident direction. The reflective grating 106 has a plurality of grooves that extend parallel to the light-receiving surface 107a of the photodetector 107 and in a direction (here, the X direction) perpendicular to the above-mentioned one direction (here, the Y direction). The photodetector 107 also has a plurality of photodetection channels arranged in a direction parallel to the above-mentioned one direction (here, the Y direction).

[0077] Here, the "incident direction of the reflected light L22 incident on the light detection unit 107" refers to the direction of the reference reflected light L22 (for example, the direction of the reflected light L22 Ｌ) in the incident direction of the reflected light L22. In addition, "so that the imaging position of the reflected light L22 approaches the plane S perpendicular to the incident direction of the reflected light L22 incident on the light detection unit 107" means that the imaging position of the reflected light L22 approaches the plane S compared to when the reflective grating 106 is not provided in the distance measurement unit 100. In other words, this means that the difference in the imaging position of the reflected light L22 in the incident direction of the reflected light L22 incident on the light detection unit 107 is less than the above-mentioned ΔY (preferably less than 10% of ΔY) in the region including the plane S.

[0078] Furthermore, the condenser 14 and the imaging lens 105 are configured so that the direction of the optical path of the reflected light L22 (the optical path of the chief ray of the reflected light L22) emitted from the imaging lens 105 is constant. In this embodiment, as shown in FIG. 8A, the optical path length between the condenser 14 and the imaging lens 105 is the sum of the focal length f1 of the condenser 14 and the focal length f2 of the imaging lens 105. In other words, the focal position of the condenser 14 on the imaging lens 105 side and the focal position of the imaging lens 105 on the condenser 14 side are the same. As a result, even if the height of the surface Wa of the object W changes, the direction of the optical path of the reflected light L22 emitted from the imaging lens 105 is constant. As a result, as shown in FIG. 8B, there is a linear relationship between the height of the surface Wa of the object W and the position of the photodetection channel into which the reflected light L22 is incident in the photodetector 107. In FIG. 8A, the light source 101, the collimator lens 102, the half mirror 103, the dichroic mirror 15, the beam splitter 20, and the like are not shown.

[0079] 8B, the image of the reflected light L22 on the light-receiving surface 107a of the light detection unit 107 has an elongated shape (here, an elliptical shape) with its longitudinal direction being a direction (here, the X direction) perpendicular to the above-mentioned one direction (the one direction in which the reflected light L22 is imaged so as to approach the plane S). This allows for deviation of the light-receiving surface 107a of the light detection unit 107 in the longitudinal direction of the image of the reflected light L22, thereby easing the precision required for the placement of each component. Note that the reason the image of the reflected light L22 on the light-receiving surface 107a of the light detection unit 107 has an elongated shape with its longitudinal direction being a direction perpendicular to the above-mentioned one direction is that astigmatism occurs in the reflected light L22 that is imaged by the imaging lens 105 and reflected by the reflective grating 106, as described above.

[0080] In the distance measuring unit 100 configured as described above, reflected light L22 is detected as follows. As shown in FIG. 6 , distance measuring light L21 emitted from the light source 101 is collimated by the collimating lens 102. The collimated distance measuring light L21 is reflected by the half mirror 103, passes through the beam splitter 20 (see FIG. 5 ), is reflected by the dichroic mirror 15, and enters the condensing unit 14. The distance measuring light L21 that enters the condensing unit 14 is condensed by the condensing unit 14 and is irradiated onto the surface Wa of the object W. The reflected light L22 reflected by the surface Wa of the object W passes through the condensing unit 14 and is reflected by the dichroic mirror 15. The reflected light L22 reflected by the dichroic mirror 15 passes through the beam splitter 20 (see FIG. 5) and the half mirror 103 in this order, is imaged by the imaging lens 105, and is also reflected by the reflective grating 106. The reflected light L22 reflected by the reflective grating 106 is incident on the photodetector 107 and detected by the photodetector 107. [Function of the control unit]

[0081] 9A, the optical axis A1 of the distance measurement light L21 is offset to one side in the Y direction (first direction) from the optical axis A of the light collecting unit 14 on the light exit surface 14b of the light collecting unit 14. The optical axis A2 of the reflected light L22 is offset to the other side in the Y direction (the opposite side) from the optical axis A of the light collecting unit 14 on the light exit surface 14b of the light collecting unit 14.

[0082] In this state, the control unit 9 controls the multiple movement mechanisms 5 and 6 so that the line α set on the target object W intersects the optical axis A and extends in the X direction (second direction) (step 1). Next, based on the detection results from the light detection unit 107, the control unit 9 controls the drive unit 18 so that the distance between the surface Wa of the target object W and the focused spot of the laser light L located within the target object W is a predetermined distance (e.g., a fixed distance), while controlling the movement mechanism 6 so that the focused spot of the laser light L moves relatively along the line α (step 2). This forms a modified region along the line α inside the target object W, a predetermined distance (e.g., a fixed distance) away from the surface Wa. In this way, the control unit 9 controls at least the multiple movement mechanisms 5 and 6 and the drive unit 18.

[0083] 9B, when processing the object W by irradiating it with laser light L, dirt (shown by dots) is more likely to adhere to the peripheral region (the peripheral region surrounding the central region) of the light emitting surface 14b of the light collecting unit 14 than to the central region (the central region including the optical axis A) of the light emitting surface 14b of the light collecting unit 14. When the direction in which the focused spot of the laser light L moves relative to the object W is the X direction, dirt is more likely to adhere to portions of the peripheral region of the light emitting surface 14b of the light collecting unit 14 on both sides of the optical axis A in the X direction. This is presumably because scattered matter emitted from the object W by irradiation with the laser light L flows backward in the traveling direction of the light collecting unit 14 (the traveling direction relative to the object W).

[0084] In other words, when the direction in which the focused spot of the laser light L moves relative to the object W is the X direction, dirt is less likely to adhere to portions on both sides of the optical axis A in the Y direction in the peripheral area of ​​the light exit surface 14b of the light focusing unit 14. In other words, dirt is less likely to adhere to areas on the light exit surface 14b of the light focusing unit 14 through which the distance measurement light L21 and the reflected light L22 pass. Therefore, in the laser processing apparatus 1, when the direction in which the focused spot of the laser light L moves relative to the object W is the X direction, height information of the surface Wa of the object W can be obtained even if dirt adheres to the light exit surface 14b of the light focusing unit 14.

[0085] 10A is a schematic diagram showing how an object W is machined by irradiating it with laser light L in a configuration (configuration of an embodiment) in which the distance measurement light L21 and the reflected light L22 straddle the optical axis A in the Y direction. Here, the configuration (configuration of an embodiment) in which the distance measurement light L21 and the reflected light L22 straddle the optical axis A in the Y direction refers to a configuration in which, on the light emission surface 14b of the light collecting unit 14, the optical axis A1 of the distance measurement light L21 is offset to one side in the Y direction from the optical axis A of the light collecting unit 14, and the optical axis A2 of the reflected light L22 is offset to the other side in the Y direction from the optical axis A of the light collecting unit 14, so that the reflection position P1 of the distance measurement light L21 on the surface Wa of the object W is offset to one side in the Y direction from the optical axis A of the light collecting unit 14.

[0086] In a configuration (configuration of the embodiment) in which the distance measurement light L21 and the reflected light L22 cross the optical axis A in the Y direction, even if a hole Wb exists behind the focused spot C of the laser light L in the relative movement direction, the reflection position P1 of the distance measurement light L21 will also pass over the hole Wb immediately after the focused spot C passes through the hole Wb, so height information of the surface Wa of the object W can be obtained even in the area immediately after the focused spot C passes through the hole Wb, and a modified region R can be accurately formed inside the object W in that area as well.

[0087] 10B is a schematic diagram showing how the object W is machined by irradiating it with laser light L in a configuration (comparison example) in which the distance measurement light L21 and the reflected light L22 straddle the optical axis A in the X direction. Here, the configuration (comparison example) in which the distance measurement light L21 and the reflected light L22 straddle the optical axis A in the X direction refers to a configuration in which, on the light emission surface 14b of the light collecting unit 14, the optical axis A1 of the distance measurement light L21 is offset to one side in the X direction from the optical axis A of the light collecting unit 14, and the optical axis A2 of the reflected light L22 is offset to the other side in the X direction from the optical axis A of the light collecting unit 14, so that the reflection position P1 of the distance measurement light L21 on the surface Wa of the object W is offset to one side in the X direction from the optical axis A of the light collecting unit 14.

[0088] In a configuration in which the distance measurement light L21 and the reflected light L22 cross the optical axis A in the X direction (the configuration of the comparative example), for example, if a hole Wb is present behind the focused spot C of the laser light L in the relative movement direction, the reflection position P1 of the distance measurement light L21 will be located on the hole Wb immediately after the focused spot C passes through the hole Wb, and therefore height information on the surface Wa of the object W cannot be obtained in the area immediately after the focused spot C passes through the hole Wb, and the modified region R cannot be accurately formed inside the object W in that area.

[0089] In the laser processing apparatus 1, when the focused spot C of the laser light L not modulated by the spatial light modulator 36 is positioned at the processing position P2 within the target object W, the reflection position P1 of the distance measurement light L21 on the surface Wa is offset to one side in the Y direction, as described above. Here, as shown in FIG. 11 , if the target object W is a wafer including multiple functional elements E arranged two-dimensionally along the surface Wa and the line α is set on the wafer so that it passes between adjacent functional elements E, depending on the depth of the processing position P2 from the surface Wa and / or the distance between the adjacent functional elements E, the reflection position P1 of the distance measurement light L21 may be positioned on the functional elements E, resulting in failure to obtain height information about the surface Wa of the target object W. Therefore, the control unit 9 controls the spatial light modulator 36 to perform at least one of the first modulation and the second modulation. Control of the first modulation and the second modulation will be described in detail below.

[0090] The control unit 9 controls the spatial light modulator 36 to perform a first modulation that moves the focused spot C of the laser light L closer to the processing position P2 in the Z direction (a third direction parallel to the optical axis A of the focusing unit 14). Specifically, the control unit 9 controls the movement mechanism 6 to move the focusing unit 14 in the Z direction, thereby positioning the focused spot C of the laser light L not modulated by the spatial light modulator 36 on the surface Wa of the target object W, as shown in FIG. 12A (at this point, the laser light L is not actually emitted). Next, the control unit 9 controls the spatial light modulator 36 to position the focused spot C of the laser light L at the processing position P2, as shown in FIG. 12B.

[0091] This allows the reflection position P1 of the distance measuring light L21 to be positioned on the line α when viewed from the Z direction, and the focal spot C of the laser light L to be moved relatively along the line α while maintaining a constant distance between the surface Wa of the object W and the focal spot C of the laser light L.

[0092] The control unit 9 also controls the spatial light modulator 36 to perform a second modulation that moves the focused spot C of the laser light L in the Y direction closer to the reflection position P1 of the distance measurement light L21. Specifically, the control unit 9 controls the movement mechanism 6 to move the focusing unit 14 in the Z direction, thereby positioning the focused spot C of the laser light L not modulated by the spatial light modulator 36 at the processing position P2, as shown in FIG. 13A (at this point, the laser light L is not actually emitted). Next, the control unit 9 controls the spatial light modulator 36 to position the focused spot C of the laser light L directly below the reflection position P1 of the distance measurement light L21 (i.e., at a position that overlaps with the reflection position P1 of the distance measurement light L21 when viewed from the Z direction), as shown in FIG. 13B (at this point, the laser light L is not actually emitted). Next, the control unit 9 controls the moving mechanism 5 to move the focusing unit 14 in the Y direction, thereby positioning the focusing spot C of the laser light L at the processing position P2, as shown in (b) of Figure 13.

[0093] This allows the reflection position P1 of the distance measuring light L21 to be positioned on the line α when viewed from the Z direction, and the focal spot C of the laser light L to be moved relatively along the line α while maintaining a constant distance between the surface Wa of the object W and the focal spot C of the laser light L.

[0094] The control unit 9 also controls the spatial light modulator 36 so that both the first modulation and the second modulation described above are performed. Specifically, the control unit 9 controls the moving mechanism 6 to move the focusing unit 14 in the Z direction, thereby positioning the focused spot C of the laser light L not modulated by the spatial light modulator 36 at a position shallower than the depth of the processing position P2, as shown in FIG. 14A (at this point, the laser light L is not actually emitted). Next, the control unit 9 controls the spatial light modulator 36 to position the focused spot C of the laser light L at the depth of the processing position P2 in the Z direction and directly below the reflection position P1 of the distance measurement light L21 in the Y direction, as shown in FIG. 14B (at this point, the laser light L is not actually emitted). Next, the control unit 9 controls the moving mechanism 5 to move the focusing unit 14 in the Y direction, thereby positioning the focused spot C of the laser light L at the processing position P2, as shown in FIG. 14B.

[0095] As a result, with the reflection position P1 of the distance measurement light L21 positioned on the line α when viewed from the Z direction, the focused spot C of the laser light L can be relatively moved along the line α while maintaining a constant distance between the surface Wa of the object W and the focused spot C of the laser light L. When both the first modulation and the second modulation are performed, the "amount of movement of the focused spot C in the Z direction" due to the modulation can be reduced compared to when only the first modulation is performed, and the "amount of movement of the focused spot C in the Y direction" due to the modulation can be reduced compared to when only the second modulation is performed.

[0096] The above-described control of the first modulation and the second modulation can be performed by setting conditions in advance when the distance between adjacent functional elements E and the "offset amount of the reflection position P1 from the optical axis A" corresponding to the processing position P2 are known. As one example, the distance between adjacent functional elements E and the depth of the processing position P2 are input via a display 91 functioning as a GUI (Graphical User Interface), the "offset amount of the reflection position P1 from the optical axis A" corresponding to the processing position P2 is read out by the control unit 9, and when the "offset amount of the reflection position P1 from the optical axis A" exceeds "½ the distance between adjacent functional elements E," the control unit 9 performs control of the first modulation and / or the second modulation.

[0097] Furthermore, control of the first modulation and the second modulation can be performed as follows, for example, when the distance between adjacent functional elements E is unknown. First, alignment is performed (S01 shown in FIG. 15 ). Specifically, the control unit 9 controls the movement mechanisms 5 and 6 based on an image of the object W acquired by the camera to move the focusing unit 14 to a position between adjacent functional elements E where the optical axis A of the focusing unit 14 intersects with the line α, as shown in FIG. 16 . Next, the height is adjusted to the reticle focus position (S02 shown in FIG. 15 ). Specifically, the control unit 9 controls the movement mechanism 6 based on the image of the object W acquired by the camera to adjust the focus position to the reticle, thereby moving the focusing unit 14 to a position between adjacent functional elements E where the focused spot C of the laser light L coincides with the surface Wa, as shown in FIG. 16 (at this point, the laser light L is not actually emitted).

[0098] Next, first AF data is acquired (S03 shown in FIG. 15). Specifically, as shown in FIG. 16, when the optical axis A of the focusing unit 14 intersects with the line α between adjacent functional elements E and the focused spot C of the laser light L coincides with the surface Wa between adjacent functional elements E (at this point, the laser light L is not actually emitted), the distance measuring unit 100 emits distance measuring light L21 and detects reflected light L22. As a result, the control unit 9 acquires, as first AF data, the "detection result by the light detecting unit 107" when the focused spot C of the laser light L not modulated by the first modulation and the second modulation is positioned on the surface Wa. In this way, the first AF data is acquired between adjacent functional elements E. Note that the height adjustment to the reticle focus position (S02 shown in FIG. 15) and the acquisition of the first AF data (S03 shown in FIG. 15) are sometimes collectively referred to as "height setting."

[0099] Next, the focusing unit 14 is moved in the Z direction so that the focused spot C of the laser light L is positioned at the processing position P2 (S04 shown in FIG. 15 ). Next, second AF data is acquired (S05 shown in FIG. 15 ). Specifically, as shown in FIGS. 17A and 17B , the optical axis A of the focusing unit 14 intersects with the line α between adjacent functional elements E, and the focused spot C of the laser light L coincides with the processing position P2 between adjacent functional elements E (at this point, the laser light L is not actually emitted). The distance measuring unit 100 then emits the distance measuring light L21 and detects the reflected light L22. As a result, the control unit 9 acquires, as second AF data, the "detection result by the light detection unit 107" when the focused spot C of the laser light L not modulated by the first modulation and the second modulation is positioned at the processing position P2. In this way, the second AF data is acquired between adjacent functional elements E.

[0100] Next, it is determined whether AF tracking is possible (S06 shown in FIG. 15 ). Specifically, the control unit 9 compares the first AF data with the second AF data to determine whether, when the focused spot C of the laser light L is positioned at the processing position P2, the reflection position P1 of the distance measurement light L21 is located on the surface Wa as shown in FIG. 17A or whether the reflection position P1 of the distance measurement light L21 is located on the functional element E as shown in FIG. 17B. As an example, when the reflection position P1 of the distance measurement light L21 is located on the functional element E, the amount of reflected light L22 detected by the light detection unit 107 is lower than when the reflection position P1 of the distance measurement light L21 is located on the surface Wa. Therefore, the control unit 9 can determine whether AF tracking is possible by comparing the first AF data with the second AF data. In addition, AF tracking means that the control unit 9 controls the drive unit 18 based on the detection results by the light detection unit 107 so that the distance between the surface Wa of the object W and the focused spot C of the laser light L located within the object W is a predetermined distance (e.g., a constant distance), while controlling the moving mechanism 6 so that the focused spot C of the laser light L moves relatively along the line α.

[0101] Next, if it is determined that AF tracking is possible, the first modulation and the second modulation are not performed, and processing of the object W is performed by irradiating the laser light L (S07 shown in FIG. 15 ). On the other hand, if it is determined that AF tracking is not possible, at least one of the first modulation and the second modulation is performed (S08 shown in FIG. 15 ), and processing of the object W is performed by irradiating the laser light L (S07 shown in FIG. 15 ). As an example, the control unit 9 controls the spatial light modulator 36 to perform the first modulation, thereby positioning the reflection position P1 of the distance measurement light L21 on the surface Wa between adjacent functional elements E, and positioning the focused spot C of the laser light L at the processing position P2, as shown in FIG. 18 .

[0102] As described above, the control unit 9 determines whether to perform at least one of the first modulation and the second modulation by comparing the first AF data with the second AF data. That is, the control unit 9 determines whether to perform at least one of the first modulation and the second modulation based on the "detection result by the light detection unit 107" when the focused spot C of the laser light L that is not modulated by the first modulation or the second modulation is positioned at the processing position P2. [Function and Effect]

[0103] In the laser processing apparatus 1 (and the laser processing method performed in the laser processing apparatus 1), when the optical axis A1 of the distance measurement light L21 is offset to one side in the Y direction from the optical axis A of the light collecting unit 14 at the light exit surface 14b of the light collecting unit 14 and the optical axis A2 of the reflected light L22 is offset to the other side in the Y direction from the optical axis A of the light collecting unit 14, the movement mechanisms 5, 6 are controlled so that the line α set on the object W extends in the X direction perpendicular to the Y direction. Then, based on the detection result by the light detection unit 107, the drive unit 18 is controlled so that the distance between the surface Wa of the object W and the focused spot C of the laser light L located within the object W is a predetermined distance, and the movement mechanism 5 is controlled so that the focused spot C of the laser light L moves relatively along the line α. Here, when processing the object W by irradiating the laser light L, dirt is particularly likely to adhere to the areas around the light exit surface 14b of the light collecting unit 14 on both sides of the optical axis A of the light collecting unit 14 in the X direction (this is a finding discovered by the present inventors). In other words, dirt is less likely to adhere to the area on the light exit surface 14b of the light collecting unit 14 through which the distance measurement light L21 and reflected light L22 pass. Therefore, even if dirt adheres to the light exit surface 14b of the light collecting unit 14, height information on the surface Wa of the object W can be obtained. Therefore, with the laser processing device 1, the processing position P2 by the laser light L can be stably set on the object W using the surface Wa of the object W as a reference.

[0104] In the laser processing apparatus 1, if the reflection position P1 of the distance measurement light L21 on the surface Wa is offset to one side when the focused spot C of the laser light L not modulated by the spatial light modulator 36 is positioned at the processing position P2 within the object W, the control unit 9 controls the spatial light modulator 36 to perform at least one of a first modulation that moves the focused spot C closer to the processing position P2 in the Z direction and a second modulation that moves the focused spot C closer to the reflection position P1 in the Y direction. This reduces the "amount of deviation in the Y direction" between the position of the focused spot C of the laser light L (i.e., the processing position P2 within the object W) and the reflection position P1 of the distance measurement light L21, so that the focused spot C of the laser light L can be accurately positioned on the line α at a predetermined distance from the surface Wa of the object W.

[0105] In the laser processing device 1, the control unit 9 determines whether to perform at least one of the first modulation and the second modulation based on the detection result when the focused spot C of the laser light L that is not modulated by the first modulation and the second modulation is positioned at the processing position P2. This makes it possible to prevent the reflection position P1 of the distance measurement light L21 from being positioned on some member due to an increase in the "amount of deviation in the Y direction" between the position of the focused spot C of the laser light L and the reflection position P1 of the distance measurement light L21.

[0106] In the laser processing apparatus 1, the control unit 9 determines whether to perform at least one of the first modulation and the second modulation by comparing the detection result when the focused spot C of the laser light L that is not modulated by the first modulation and the second modulation is positioned on the surface Wa with the detection result when the focused spot C of the laser light L that is not modulated by the first modulation and the second modulation is positioned at the processing position P2. This makes it possible to reliably determine whether the reflection position P1 of the distance measurement light L21 is located on any member when the focused spot C of the laser light L is positioned at the processing position P2 within the target object W, and therefore makes it possible to reliably prevent the reflection position P1 of the distance measurement light L21 from being located on any member.

[0107] In the laser processing device 1, when the object W is a wafer including a plurality of functional elements E arranged two-dimensionally along the surface Wa, and when the line α is set on the wafer so as to pass between adjacent functional elements E among the plurality of functional elements E, the detection result when the focused spot C of the laser light L not modulated by the first modulation and the second modulation is positioned at the processing position P2 is acquired between the adjacent functional elements E. This makes it possible to reliably determine whether the reflection position P1 of the distance measurement light L21 is located on the functional element E when the focused spot C of the laser light L is positioned at the processing position P2 within the object W, thereby reliably preventing the reflection position P1 of the distance measurement light L21 from being located on the functional element E. [Modification]

[0108] The present disclosure is not limited to the above-described embodiments. For example, in the above-described embodiments, the line α is set on the object W so as to extend in the X direction (second direction) perpendicular to the Y direction (first direction). However, the line α may be set on the object W so as to extend in a direction (second direction) inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the Y direction (first direction). The direction inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the Y direction refers to a direction parallel to a line passing through the optical axis A in an angle range of 45 degrees or more and 135 degrees or less counterclockwise with respect to the Y direction, within each range of 0 degrees or more and 180 degrees or less counterclockwise with respect to the Y direction, as shown by hatching in FIG. 19 .

[0109] The circuit unit 19 constituting a part of the control unit 9 may be included in the control unit 9. The surface Wa of the object W is not limited to the surface of the object W on the incident side of the laser light L, but may be another surface (predetermined surface) of the object. This is because in the distance measuring unit 100, the reflected light reflected by each surface is spatially separated from each other.

[0110] In the above embodiment, the dichroic mirror 15 transmits the laser light L and reflects the distance measurement light L21 and the reflected light L22, but instead of the dichroic mirror 15, an optical element that transmits the distance measurement light L21 and the reflected light L22 and reflects the laser light L may be used.

[0111] In the above embodiment, the reflective grating 106 disposed between the imaging lens 105 and the photodetector 107 is used as the optical path adjuster that adjusts the optical path of the reflected light L22. However, any other configuration may be used as long as it can adjust the optical path of the reflected light L22 so that the imaging position of the reflected light L22 approaches the plane S. Examples of such configurations include a spatial light modulator, a digital mirror device, a transmission grating, a prism, etc. A cylindrical lens may be provided so that the image of the reflected light L22 on the light receiving surface 107a of the photodetector 107 has an elongated shape whose longitudinal direction is perpendicular to one direction (the one direction in which the reflected light L22 is imaged so as to approach the plane S).

[0112] When the distance measurement light L21 passes through the light collecting unit 14, the distance by which the optical axis A1 of the distance measurement light L21 is offset from the optical axis A of the light collecting unit 14 may be adjustable. As an example, by adjusting the position of the half mirror 103 shown in Fig. 6, the distance by which the optical axis A1 of the distance measurement light L21 is offset from the optical axis A of the light collecting unit 14 can be adjusted. By adjusting this distance, the measurement range for the height of the surface Wa of the object W and the detection sensitivity of the light detecting unit 107 can be adjusted.

[0113] In the above embodiment, the light receiving surface 107a of the light detection unit 107 is located on the plane S, but the light receiving surface 107a of the light detection unit 107 may be located along the plane S. For example, even if the light receiving surface 107a of the light detection unit 107 forms an angle with the plane S, as long as the angle is less than 5°, the height of the surface Wa of the object W can be measured with sufficient accuracy.

[0114] In the above embodiment, the plane S was a plane perpendicular to the incident direction of the reflected light L22 incident on the light detection unit 107, but the plane S may be any plane that intersects with the incident direction, such as by being inclined at an angle of 30° or less with respect to the incident direction.

[0115] For reference, the following inventions [I] and [II] of the laser processing device are valid regardless of whether the line set on the object extends in a second direction inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the first direction. According to these inventions, the "amount of deviation in the first direction" between the position of the focused spot of the processing light (i.e., the processing position within the object) and the reflection position of the non-processing light can be reduced, so that the focused spot of the processing light can be accurately positioned on the line at a predetermined distance from a predetermined surface of the object. [I] "A light source including: a support portion that supports an object; a first light source that emits processing light; a second light source that emits non-processing light; a focusing portion that transmits the processing light and the non-processing light toward the object; a spatial light modulator that modulates the processing light on an optical path of the processing light from the first light source to the focusing portion; a light detection portion that detects reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing portion from the object side; a drive portion that drives at least one of the support portion and the focusing portion; and a control portion that controls at least the drive portion, wherein the optical axis of the non-processing light is offset from the optical axis of the focusing portion to one side in a first direction at the light exit surface of the focusing portion, and the optical axis of the reflected light is offset from the optical axis of the focusing portion to the other side in the first direction at the light exit surface, the control unit controls the spatial light modulator so that, when the focused spot of the processing light not modulated by the spatial light modulator is positioned at a processing position within the object and the reflection position of the non-processing light on the specified surface is offset to the one side, at least one of a first modulation that moves the focused spot closer to the processing position in a direction parallel to the optical axis of the focusing unit and a second modulation that moves the focused spot closer to the reflection position in the first direction is performed; and the control unit controls the drive unit so that the distance between the specified surface and the focused spot of the processing light located within the object is a specified distance, based on the detection result by the light detection unit, and controls the drive unit so that the focused spot moves relatively along a line set on the object." [II] "A laser processing method performed in a laser processing apparatus including: a support portion that supports an object; a first light source that emits processing light; a second light source that emits non-processing light; a focusing portion that transmits the processing light and the non-processing light toward the object; a spatial light modulator that modulates the processing light on an optical path of the processing light from the first light source to the focusing portion; a light detection portion that detects reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing portion from the object side; and a drive portion that drives at least one of the support portion and the focusing portion, wherein the optical axis of the non-processing light is offset to one side in a first direction from the optical axis of the focusing portion at a light emission surface of the focusing portion, and the optical axis of the reflected light is offset to the other side in the first direction from the optical axis of the focusing portion at the light emission surface, a first step of modulating the processing light by the spatial light modulator so that, when the reflected position of the non-processing light on the predetermined surface is offset to the one side when the focused spot of the processing light not modulated by the spatial light modulator is positioned at the processing position within the object, at least one of a first modulation that moves the focused spot closer to the processing position in a direction parallel to the optical axis of the focusing unit and a second modulation that moves the focused spot closer to the reflection position in the first direction is performed; and a second step of driving at least one of the support unit and the focusing unit with the driving unit so that the focused spot moves relatively along a line set on the object, while controlling the driving unit so that the distance between the predetermined surface and the focused spot of the processing light located within the object is a predetermined distance based on the detection result by the light detection unit.

[0116] 1...laser processing device, 5, 6...movement mechanism (drive unit), 7...support unit, 9...control unit, 14...focusing unit, 14b...light emission surface, 18...drive unit, 19...circuit unit (control unit), 36...spatial light modulator, 81, 82...light source (first light source), 101...light source (second light source), 107...light detection unit, A, A1, A2...optical axis, C...focused spot, E...functional element, L...laser light (processing light), L21...distance measurement light (non-processing light), L22...reflected light, P1...reflection position, P2...processing position, R...modified area, W...target object, Wa...surface (predetermined surface), α...line.

Claims

1. A laser beam irradiation system comprising: a support section for supporting an object; a first light source for emitting processing light; a second light source for emitting non-processing light; a focusing section for transmitting the processing light and the non-processing light toward the object; a light detection section for detecting reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing section from the object side; a drive section for driving at least one of the support section and the focusing section; and a control section for controlling at least the drive section, wherein the optical axis of the non-processing light is offset from the optical axis of the focusing section to one side in a first direction on the light emission surface of the focusing section, and the optical axis of the reflected light is offset from the optical axis of the focusing section to the other side in the first direction on the light emission surface, and the control section controls the drive section so that a line set on the object extends in a second direction inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the first direction, The control unit controls the drive unit based on the detection result by the light detection unit so that the distance between the specified surface and the focused spot of the processing light located within the object is a specified distance, and also controls the drive unit so that the focused spot moves relatively along the line.

2. A laser processing device as described in claim 1, further comprising a spatial light modulator that modulates the processing light on the optical path of the processing light from the first light source to the focusing unit, wherein the control unit controls the spatial light modulator so that, when the focused spot of the processing light not modulated by the spatial light modulator is positioned at a processing position within the object and the reflection position of the non-processing light on the specified surface is offset to the one side, at least one of a first modulation that moves the focused spot closer to the processing position in a third direction parallel to the optical axis of the focusing unit and a second modulation that moves the focused spot closer to the reflection position in the first direction is performed.

3. The laser processing device according to claim 2, wherein the control unit determines whether to perform at least one of the first modulation and the second modulation based on the detection result when the focused spot of the processing light that is not modulated by the first modulation and the second modulation is positioned at the processing position.

4. The laser processing device according to claim 3, wherein the control unit determines whether to perform at least one of the first modulation and the second modulation by comparing the detection result when the focused spot of the processing light not modulated by the first modulation and the second modulation is positioned on the specified plane with the detection result when the focused spot of the processing light not modulated by the first modulation and the second modulation is positioned at the processing position.

5. A laser processing device as described in claim 3 or 4, wherein the object is a wafer including a plurality of functional elements arranged two-dimensionally along the predetermined plane, the line is set on the wafer so as to pass between adjacent functional elements of the plurality of functional elements, and the detection result when the focused spot of the processing light not modulated by the first modulation and the second modulation is positioned at the processing position is obtained between the adjacent functional elements.

6. A laser processing method carried out by a laser processing device comprising: a support part for supporting an object; a first light source for emitting processing light; a second light source for emitting non-processing light; a focusing part for transmitting the processing light and the non-processing light toward the object; a light detection part for detecting reflected light of the non-processing light that is reflected by a predetermined surface of the object and transmitted through the focusing part from the object side; and a drive part for driving at least one of the support part and the focusing part, wherein the optical axis of the non-processing light is offset from the optical axis of the focusing part to one side in a first direction on the light emission surface of the focusing part, and the optical axis of the reflected light is offset from the optical axis of the focusing part to the other side in the first direction on the light emission surface, comprising: a first step of driving at least one of the support part and the focusing part by the drive part so that a line set on the object extends in a second direction inclined at an angle of 45 degrees or more and 135 degrees or less with respect to the first direction; a second step of controlling the driving unit based on the detection result by the light detection unit so that the distance between the specified surface and the focused spot of the processing light located within the object becomes a specified distance, and driving at least one of the support unit and the focusing unit so that the focused spot moves relatively along the line.

Images