JP7523985B2 - Laser processing device and laser processing method - Google Patents

Description

The present invention relates to a laser processing device and a laser processing method.

Patent Document 1 describes a laser dicing device. This laser dicing device includes a stage for moving the wafer, a laser head for irradiating the wafer with laser light, and a control unit for controlling each component. The laser head includes a laser light source for emitting processing laser light for forming a modified region inside the wafer, a dichroic mirror and a condenser lens arranged in this order on the optical path of the processing laser light, and an AF device.

Patent No. 5743123

In the device described in Patent Document 1, a calibration operation is performed to measure the output characteristics of the autofocus error signal. In the calibration operation, the stage is controlled so that the reference position of the center of the wafer is directly under the focusing lens. Next, the second actuator is controlled to move the focus lens group that contributes to adjusting the focusing position of the AF laser light. At this time, the autofocus error signal is set to zero. This causes the focusing point of the AF laser light to coincide with the surface of the wafer.

Then, by controlling the first actuator, the focusing lens for focusing the AF laser light and the processing laser light on the wafer is moved throughout its movable range while measuring the output characteristics of the autofocus error signal and storing the output characteristics as a look-up table. In this way, in the device described in Patent Document 1, the AF device is calibrated at a reference position in the center of the wafer prior to laser processing.

However, as described above, if calibration is performed uniformly at a reference position in the center of the wafer, regardless of the distribution of displacement on the wafer surface, and the actuator is then driven up and down around the height of the wafer surface at that reference position, the following problem may arise. That is, for example, if the reference position is the upper (or lower) limit of the height of the wafer surface, then only the lower (or upper) side of the center of the actuator's movable range will be used during actual processing, and there will be many areas where the displacement of the wafer surface exceeds the actuator's movable range.

In general, the measurement range in which an AF device (displacement sensor) can measure the displacement of the wafer surface is wider than the movable range of the actuator of the focusing lens. Therefore, in areas where the displacement of the wafer surface exceeds the movable range of the actuator, even if it is possible to measure the amount of displacement, it is difficult to perform processing (tracking processing) while moving the focusing lens appropriately according to the amount of displacement. In other words, in such cases, the range in which tracking processing is possible is narrowed.

The present invention aims to provide a laser processing device and a laser processing method that can prevent the possible range of follow-up processing from being narrowed.

The laser processing device according to the present invention includes a support unit for supporting an object including a first surface and a second surface opposite to the first surface, a laser irradiation unit for irradiating the object supported by the support unit with laser light from the first surface side via a focusing lens, an actuator for driving the focusing lens along the Z direction from the second surface toward the first surface, and a first moving unit for moving at least one of the support unit and the laser irradiation unit so that the focusing point of the laser light moves relative to the object along the X direction intersecting the Z direction, and a laser processing device for irradiating the object with laser light while controlling at least the actuator, the laser irradiation unit, and the first moving unit. and a control unit that performs laser processing of the object by using the actuator. The control unit performs an acquisition process to acquire displacement information indicating the displacement of the first surface in the Z direction, an association process to associate a specific value of a central range, which is a part of the range of displacement including the central value of the displacement, with a reference voltage for the actuator drive voltage based on the displacement information after the acquisition process, and a processing process to relatively move the focal point along a line along the X direction while adjusting the position of the focal point of the laser light in the Z direction according to the displacement by driving the actuator around the reference voltage after the association process, thereby performing laser processing of the object along the line.

The laser processing method according to the present invention is a laser processing method that performs laser processing by controlling at least a laser irradiation unit for irradiating a laser beam from the first surface side through a condensing lens to an object supported by a support unit, which includes a first surface and a second surface opposite to the first surface, an actuator for driving the condensing lens along the Z direction from the second surface toward the first surface, and a first moving unit for moving at least one of the support unit and the laser irradiation unit so that the focal point of the laser beam moves relative to the object along the X direction intersecting the Z direction. The method includes an acquisition step of acquiring displacement information indicating the displacement of the first surface in the Z direction, an association step of associating a specific value of a central range, which is a part of the range of displacement including the central value of the displacement, with a reference voltage for the drive voltage of the actuator based on the displacement information after the acquisition step, and a processing step of driving the actuator around the reference voltage after the association step to relatively move the focal point along a line along the X direction while adjusting the position of the focal point of the laser beam in the Z direction according to the displacement, thereby performing laser processing of the object along the line.

In these devices and methods, first, displacement information indicating the displacement of the first surface of the object in the Z direction is acquired. Then, based on the acquired displacement information, a specific value of a central range, which is a part of the range of displacement including the central value of the displacement of the first surface of the object, is associated with a reference voltage of the driving voltage of the actuator. Then, by driving the actuator around the reference voltage, the focal point of the laser light in the Z direction is relatively moved along a line along the X direction while adjusting the position of the focal point of the laser light in the Z direction according to the displacement of the first surface of the object, and laser processing (tracking processing) of the object is performed along the line. For this reason, during tracking processing, it is possible to avoid using only the lower side or upper side than the center of the movable range of the actuator. Therefore, it is possible to suppress the possible range of tracking processing from being narrowed, compared to, for example, a case in which the displacement amount (height) of the first surface at the center of the object is uniformly associated with the reference voltage of the actuator.

In the laser processing device according to the present invention, the specific value may be the center value of the displacement. In this case, the lower and upper sides of the center of the actuator's movable range are used equally in the tracking processing. This reliably prevents the possible range of tracking processing from being narrowed.

The laser processing device according to the present invention may be provided with a displacement sensor that is arranged to move integrally with the laser irradiation unit, and that measures the displacement of the first surface and acquires displacement information by emitting measurement light toward the object and inputting reflected light of the measurement light. In this case, the displacement sensor can be used to acquire displacement information indicating the displacement of the first surface of the object.

In the laser processing device according to the present invention, the control unit may continuously measure the displacement using a displacement sensor to obtain displacement information. In this case, it is possible to obtain displacement information that is more consistent with the actual displacement of the first surface of the object.

In the laser processing device according to the present invention, the control unit may acquire displacement information by measuring the displacement discretely at multiple locations on the first surface using a displacement sensor. In this case, the time required for the acquisition process can be shortened.

The laser processing device according to the present invention includes a second moving unit for moving the laser irradiation unit and the displacement sensor relative to the object along the Z direction, and the control unit may execute a first process in the association process, in which the first moving unit controls the laser irradiation unit and the displacement sensor to a first position where the displacement of the first surface becomes a specific value, a second process, after the first process, in which the second moving unit controls the laser irradiation unit and the displacement sensor to move relatively along the Z direction so that the measurement light is focused on the first surface, and a third process, after the second process, in which the displacement measurement value of the displacement sensor when the measurement light is focused on the first surface is associated with a reference voltage. In this way, in the association process, the actual measurement value of the displacement of the first surface of the object can be associated with a reference voltage for the drive voltage of the actuator as a specific value.

The laser processing device according to the present invention includes a second moving unit for moving the laser irradiation unit and the displacement sensor relative to the object along the Z direction, and the control unit may execute a fourth process in the association process, in which the first moving unit is controlled to move the laser irradiation unit and the displacement sensor to a second position where the displacement of the first surface is a lower limit or an upper limit, a fifth process in which the second moving unit is controlled to relatively move the laser irradiation unit and the displacement sensor along the Z direction after the fourth process so that the measurement light is focused on the first surface, and a sixth process in which the offset amount is set so that the offset value obtained by adding the offset amount to the measured value of the displacement of the displacement sensor when the measurement light is focused on the first surface is included in the central range after the fifth process, and the offset value is associated with the reference voltage as a specific value. In this way, in the association process, the offset value offset from the actual measured value of the displacement of the first surface of the object can be associated with the reference voltage of the actuator drive voltage as a specific value.

In the laser processing device according to the present invention, the control unit executes, between the acquisition process and the association process, a determination process for determining whether or not the displacement exceeds the movable range of the actuator, and a notification process for notifying the user that the displacement exceeds the movable range when the result of the determination process indicates that the displacement does not exceed the movable range, and the control unit may execute the association process and the processing process when the result of the determination process indicates that the displacement does not exceed the movable range. In this case, it becomes possible to recognize when the displacement of the first surface of the object exceeds the movable range of the actuator.

In the laser processing device according to the present invention, the control unit executes a determination process between the acquisition process and the association process to determine whether or not the displacement exceeds the movable range of the actuator, and if the result of the determination process indicates that the displacement exceeds the movable range, the control unit may divide the line into multiple parts so that the displacement is included in the movable range, and execute the association process and processing process for each part. In this case, the possible range of tracking processing is expanded.

The present invention provides a laser processing device and a laser processing method that can prevent the possible range of follow-up processing from being narrowed.

FIG. 1 is a schematic diagram showing a configuration of a laser processing apparatus according to an embodiment. FIG. 2 is a diagram showing the configuration of the laser irradiation unit shown in FIG. FIG. 3 is a diagram showing an example of laser processing (follow-up processing). FIG. 4 is a diagram showing the relationship between the displacement sensor and the actuator. FIG. 5 is a diagram for explaining the problems with follow-up machining. FIG. 6 is a flowchart showing an example of a laser processing method. FIG. 7 is a diagram for explaining the problems with follow-up machining. 3 is a flowchart showing a laser processing method according to the first embodiment. 9A to 9C are diagrams showing the operation and effect of the laser processing method shown in FIG. 8 . FIG. 10 is a diagram for explaining the problem of follow-up machining. FIG. 11 is a flowchart showing the laser processing method according to the second embodiment. 12A to 12C are diagrams showing the action and effect after the laser processing shown in FIG. 11 . FIG. 13 is a flowchart showing the laser processing method according to the third embodiment. FIG. 14 is a flowchart showing the laser processing method according to the fourth embodiment. FIG. 15 is a flowchart showing a laser processing method according to the fifth embodiment. FIG. 16 is a graph showing a case where the displacement of the object exceeds the movable range of the actuator. FIG. 17 is a flowchart showing the laser processing method according to the fifth embodiment. FIG. 18 is a flowchart showing the laser processing method according to the fifth embodiment. FIG. 19 is a flowchart showing the laser processing method according to the fifth embodiment. FIG. 13 is a plan view of an object for explaining a modified example. 13 is a graph of a displacement sensor voltage for explaining a modified example.

An embodiment will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations may be omitted. In addition, each drawing may show an orthogonal coordinate system defined by an X-axis, a Y-axis, and a Z-axis.
[Outline of laser processing device and laser processing]

Figure 1 is a schematic diagram showing the configuration of a laser processing device according to one embodiment. Figure 2 is a diagram showing the configuration of the laser irradiation unit shown in Figure 1. Figure 2 shows an imaginary line A indicating the planned laser processing. As shown in Figures 1 and 2, the laser processing device 1 includes a stage (support unit) 2, a laser irradiation unit 3, drive units (movement units) 4 and 5, and a control unit 6. The laser processing device 1 is a device for forming a modified region 12 in an object 11 by irradiating the object 11 with laser light L.

The stage 2 supports the object 11, for example, by holding a film attached to the object 11. The stage 2 is rotatable around an axis parallel to the Z direction. The stage 2 may be movable along both the X direction and the Y direction. The X direction and the Y direction are a first horizontal direction and a second horizontal direction that intersect (are perpendicular to) each other, and the Z direction is a vertical direction. The object 11 has a first surface 11a and a second surface 11b opposite the first surface 11a. The object 11 is, for example, a wafer containing a semiconductor (a silicon wafer is one example).

The laser irradiation unit 3 focuses the laser light L, which is transparent to the object 11, and irradiates the object 11. When the laser light L is focused inside the object 11 supported by the stage 2, the laser light L is particularly absorbed in a portion corresponding to the focusing point C of the laser light L, and a modified region 12 is formed inside the object 11. The focusing point C is the point where the laser light L is focused. However, when the laser light L is modulated according to the modulation pattern presented to the spatial light modulator 7 (for example, when various aberrations are imparted), etc., and the laser light L is not focused at one point, the focusing point C may be a position where the beam intensity of the laser light L is highest or an area within a predetermined range from the center of gravity of the beam intensity.

The modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding unmodified region. Examples of the modified region 12 include a melting treatment region, a crack region, an insulation breakdown region, and a refractive index change region. The modified region 12 can be formed such that a crack extends from the modified region 12 to the incident side of the laser light L and to the opposite side. Such modified region 12 and cracks are used, for example, to cut the object 11.

As an example, when the stage 2 is moved along the X direction and the focal point C is moved along the X direction relative to the object 11, multiple modified spots 12s are formed in a row along the X direction. One modified spot 12s is formed by irradiating one pulse of laser light L. A row of modified regions 12 is a collection of multiple modified spots 12s lined up in a row. Adjacent modified spots 12s may be connected to each other or separated from each other depending on the relative moving speed of the focal point C with respect to the object 11 and the repetition frequency of the laser light L.

The driving unit 4 includes a first unit 41 that moves the stage 2 in one direction in a plane intersecting (orthogonal) to the Z direction, and a second unit 42 that moves the stage 2 in another direction in a plane intersecting (orthogonal) to the Z direction. As an example, the first unit 41 moves the stage 2 along the X direction, and the second unit 42 moves the stage 2 along the Y direction. The driving unit 4 also rotates the stage 2 around an axis parallel to the Z direction. The driving unit 5 supports the laser irradiation unit 3. The driving unit 5 moves the laser irradiation unit 3 along the X direction, Y direction, and Z direction. When the stage 2 and/or the laser irradiation unit 3 are moved in a state in which the focal point C of the laser light L is formed, the focal point C is moved relative to the object 11. That is, the driving units 4 and 5 are a first moving unit and a second moving unit that move at least one of the stage 2 and the laser irradiation unit 3 so that the focal point C of the laser light L moves relative to the object 11.

The control unit 6 controls the operation of the stage 2, the laser irradiation unit 3, and the drive units 4 and 5. The control unit 6 has a processing unit, a memory unit, and an input reception unit (not shown). The processing unit is configured as a computer device including a processor, memory, storage, and a communication device. In the processing unit, the processor executes software (programs) loaded into the memory, etc., and controls the reading and writing of data in the memory and storage, as well as communication by the communication device. The memory unit is, for example, a hard disk, and stores various types of data. The input reception unit is an interface unit that displays various types of information and receives input of various types of information from the user. The input reception unit constitutes a GUI (Graphical User Interface).

2, the laser irradiation unit 3 has a light source 31, a spatial light modulator 7, an actuator 8, a displacement sensor 9, a condenser lens 33, and a mirror 34. The light source 31 outputs laser light L, for example, by a pulse oscillation method. Note that the laser irradiation unit 3 may be configured not to have the light source 31 and to introduce the laser light L from outside the laser irradiation unit 3.

The spatial light modulator 7 modulates the laser light L output from the light source 31, for example, by a modulation pattern formed in a liquid crystal layer. The condenser lens 33 condenses the laser light L modulated by the spatial light modulator 7 and output from the spatial light modulator 7 toward the object 11. In other words, the laser irradiation unit 3 irradiates the object 11 supported on the stage 2 with the laser light L from the first surface 11a side via the condenser lens 33.

The mirror 34 is disposed in front of the focusing lens 33 (here, between the focusing lens 33 and the spatial light modulator 7) on the optical path of the laser light L. The mirror 34 transmits the laser light L toward the focusing lens 33.

The displacement sensor 9 outputs the measurement laser light LA. The mirror 34 is disposed on the optical path of the measurement laser light LA and reflects the measurement laser light LA toward the condenser lens 33. As a result, the measurement laser light LA is irradiated to the object 11 with the same optical axis as the optical axis of the laser light L. In other words, here, the displacement sensor 9 is configured coaxially with the laser light L. The displacement sensor 9 inputs the reflected light LR of the measurement laser light LA by the object 11 via the condenser lens 33 and the mirror 34. The displacement sensor 9 outputs information about the reflected light LR to the control unit 6 as displacement information about the displacement of the first surface 11a of the object 11 (height in the Z-axis direction, including unevenness, inclination, etc.). The displacement information is, for example, a voltage value of the displacement sensor 9 according to the reflected light LR (hereinafter, sometimes referred to as the "displacement sensor voltage").

In this way, the laser processing device 1 is arranged to move integrally with the laser irradiation unit 3, and is provided with a displacement sensor 9 for measuring the displacement of the first surface 11a and acquiring displacement information by emitting a measurement laser light (measurement light) LA toward the object 11 and inputting the reflected light LR of the measurement laser light LA. In addition, the control unit 6 can acquire displacement information (displacement sensor voltage) indicating the displacement of the first surface 11a of the object 11 by controlling the displacement sensor 9.

As described above, the displacement sensor 9 is a sensor coaxial with the laser light L, and is, for example, an astigmatism type sensor. However, the displacement sensor 9 may be a sensor with a different axis from the laser light L. In this case, the displacement sensor 9 may be a sensor using a triangulation type, a laser confocal type, a white light confocal type, a spectral interference type, an astigmatism type, or the like.

The actuator 8 is provided on the focusing lens 33. The actuator 8 is for driving the focusing lens 33 along the Z direction. The actuator 8 drives the focusing lens 33 along the Z direction by expanding and contracting according to the magnitude of the applied drive voltage, centered on the amount of expansion when a reference voltage is applied. Here, the Z direction is the direction from the second surface 11b to the first surface 11a of the object 11.

The control unit 6 is configured as a computer device as described above, and controls at least the stage 2, the laser irradiation unit 3 including the actuator 8 and the displacement sensor 9, and the drive units 4 and 5, while irradiating the object 11 with laser light L to perform laser processing of the object 11. Details of the processing of the control unit 6 will be described later.

In the laser processing device 1 as described above, laser processing is performed as follows. FIG. 3(a) is a plan view of the object 11, and FIG. 3(b) is a cross-sectional view showing the state of laser processing. Here, as an example, a circular line A concentric with the center 11c of the object 11 when viewed from the Z direction is set on the object 11. Line A is a line indicating the processing plan where processing is performed by irradiating the laser light L. Here, the object 11 is supported on the stage 2 with the first surface 11a facing the focusing lens 33. That is, here, the first surface 11a is the incident surface of the laser light L and the measurement laser light LA.

The control unit 6 controls the displacement sensor 9 to obtain displacement information (displacement sensor voltage) indicating the displacement of the first surface 11a from the displacement sensor 9. The control unit 6 also controls the laser irradiation unit 3 to irradiate the target object 11 with laser light L from the first surface 11a side. In this state, the control unit 6 controls the drive units 4 and 5 to move the focal point C of the laser light L along the line A relative to the target object 11.

At the same time, the control unit 6 controls the actuator 8 based on the displacement information to move the condenser lens 33 along the Z direction so that the focal point C of the laser light L is constant at a desired depth (Z-axis height) Ds from the first surface 11a. As a result, even if the first surface 11a is displaced in the Z direction, the modified region 12 is formed along the line A at a constant depth Ds from the first surface 11a. In this way, the laser processing apparatus 1 can perform tracking processing using the actuator 8 and the displacement sensor 9.
[Problem description]

Here, FIG. 4 is a diagram showing the relationship between the displacement sensor and the actuator. The vertical axis of FIG. 4(a) indicates the displacement sensor voltage VD of the displacement sensor 9, and the horizontal axis of FIG. 4(a) indicates the displacement along the Z direction of the first surface 11a of the object 11 (Z-axis height). FIG. 4(a) also shows the displacement sensor voltage VD and the movable range RA of the actuator 8.

As shown in FIG. 4, here, the movable range RA of the actuator 8 is narrower than the measurement range RD, which is the range of Z-axis height within which the displacement sensor voltage VD can change in response to the displacement of the first surface 11a and within which the displacement sensor 9 can measure the displacement of the first surface 11a. Therefore, as shown in FIG. 4(b), in a portion where the displacement of the first surface 11a of the object 11 becomes a displacement OD that exceeds the movable range RA of the actuator 8, even if the displacement OD can be measured by the displacement sensor 9, it becomes difficult to perform follow-up processing when laser processing proceeds along the line A.

As an example, such a problem may occur when the first surface 11a of the object 11 is displaced uniformly so that the thickness of the object 11 increases from the center 11c toward the outer edge, as shown in FIG. 5(a), and laser processing is performed along line A set in the relatively thick outer edge portion. Laser processing of such an object 11 will now be described in detail.

Figure 6 is a flow chart showing an example of a laser processing method. As shown in Figures 5 and 6, here, alignment is performed first (step S11). More specifically, in step S11, for example, the object 11 is imaged using light passing through the object 11 to obtain an image of the object 11. Then, based on initial information including a reference image of the object 11 that is stored in advance and the obtained image, alignment of the irradiation position of the laser light L in the directions along the first surface 11a (X direction and Y direction) is performed.

Then, the driving units 4 and 5 are driven, and the laser irradiation unit 3 is moved relative to the object 11 in the X and Y directions, so that the laser irradiation unit 3 is moved to the center 11c of the object 11 (step S12). Note that, as in the following, the laser irradiation unit 3 here includes a displacement sensor 9. Therefore, moving the laser irradiation unit 3 means moving the displacement sensor 9 as well.

Next, the height is set at the center 11c of the object 11, for example, using a reticle (step S13). More specifically, in step S13, the driving units 4 and 5 are driven to move the entire laser irradiation unit 3 relative to the object 11 along the Z direction so that the measurement laser light LA is focused on the first surface 11a of the object 11 at the center 11c of the object 11, and the focal point of the measurement laser light LA is moved relative to the object 11 along the Z direction. Then, a height set voltage is obtained, which is the value of the displacement sensor voltage VD when the focal point of the measurement laser light LA coincides with the first surface 11a.

Next, a reference voltage for the drive voltage of the actuator 8 is set (step S14). In this step S14, the reference voltage of the actuator 8 is associated with the height set voltage acquired in step S13. More specifically, for example, when the displacement sensor voltage of the displacement sensor 9 is the height set voltage, the reference voltage is set so that the reference voltage is applied to the actuator 8 (i.e., so that the amount of expansion and contraction of the actuator 8 corresponds to the reference voltage). As a result, for example, when the displacement sensor voltage VD varies within a range including the height set voltage in response to the displacement of the first surface 11a, the amount of expansion and contraction of the actuator 8 also varies around the amount corresponding to the reference voltage.

In the next step, the driving units 4 and 5 are driven to move the laser irradiation unit 3 in the X and Y directions, and the laser irradiation unit 3 is moved onto the line A (step S15). Then, processing is performed (step S16). In step S16, the driving units 4 and 5 are driven to move the focal point C of the laser light L along the line A relative to the target object 11. At this time, the displacement of the first surface 11a is measured by the displacement sensor 9. Then, the actuator 8 is expanded or contracted according to the displacement information (displacement sensor voltage VD) indicating the displacement of the first surface 11a measured by the displacement sensor 9, and the focusing lens 33 is moved along the Z direction.

Figure 5(b) is a graph showing an example of the relationship between the displacement sensor voltage VD and the Z-axis height AD of the focusing lens 33 (focus point C) at this time. The horizontal axis of Figure 5(b) shows the movement distance of the focusing point C (laser irradiation unit 3) in the X and Y directions. As shown in Figure 5(b), due to the shape of the object 11, the displacement sensor voltage VD increases (as the movement distance increases) from the center 11c of the object 11 toward the line A on the outer edge side.

The movable range RA of the actuator 8 is a range centered on a central value Ao corresponding to the reference voltage. The reference voltage is associated with a height set voltage that indicates the displacement of the first surface 11a at the center 11c of the object 11. As described above, the object 11 has a shape in which the thickness increases from the center 11c toward the outer edge. Therefore, since the Z-axis height of the first surface 11a of the object 11 is lowest at the center 11c, the height set voltage becomes the lower limit of the displacement sensor voltage VD.

Therefore, the actuator 8 is not driven below the center value Ao of its movable range RA (e.g., the extension side), but only above the center value Ao of its movable range RA (e.g., the contraction side). As a result, from the position Po corresponding to the center 11c to the distance Pa, the actuator 8 is driven in response to the change in the displacement sensor voltage VD to adjust the Z-axis height AD of the focal point C, but after the distance Pa, the displacement sensor voltage VD exceeds the movable range RA of the actuator 8, so the actuator 8 is stopped and the Z-axis height AD of the focal point C is not adjusted. In other words, the above problem of making tracking processing difficult may occur.

Next, we will explain another example in which tracking processing is difficult. Figure 7(a) is a cross-sectional view of the object 11, and Figure 7(b) is a cross-sectional view of the object 11 when unfolded along line A. In this example, there is no uniform displacement of the first surface 11a of the object 11 as shown in Figure 5(a), but there is a displacement along line A, i.e., a distribution of the Z-axis height of the first surface 11a along line A.

For such an object 11, similar to the laser processing method shown in FIG. 6, if the height is set at the center 11c of the object 11 and the actuator 8 is driven based on the reference voltage associated with the height set voltage at that time, the actuator 8 is driven in response to changes in the displacement sensor voltage VD until the moving distance reaches distance Pb and after distance Pc, and the Z-axis height AD of the focal point C is adjusted. However, between distances Pb and Pc, the displacement sensor voltage VD exceeds the movable range RA of the actuator 8, so the actuator 8 is stopped and the Z-axis height AD of the focal point C is not adjusted. In other words, the above-mentioned problem of making tracking processing difficult may occur here as well.

As described above, if height setting is performed uniformly at the center 11c of the object 11 regardless of the displacement distribution of the first surface 11a of the object 11, and the actuator 8 is driven around a reference voltage corresponding to the height set voltage obtained at the center 11c, there is a risk that the range of possible tracking processing will be narrowed.
[First embodiment]

In contrast, in this embodiment, the possible range of follow-up processing is prevented from being narrowed. Next, a first embodiment of the laser processing device and laser processing method will be specifically described. Here, the target object 11 is the same as that shown in FIG. 7. FIG. 8 is a flowchart showing the laser processing method according to the first embodiment.

As shown in FIG. 8, here, first, alignment is performed in the same manner as in step S11 (step S21). More specifically, in step S21, the control unit 6 controls an alignment camera (not shown) to capture an image of the object 11 using light transmitted through the object 11, thereby acquiring an image of the object 11. Then, based on initial information including a reference image of the object 11 previously stored in a memory or the like of the control unit 6 and the acquired image, alignment is performed for the irradiation position of the laser light L in the directions along the first surface 11a (X direction and Y direction).

Next, line A is traced (step S22, acquisition step) to acquire displacement information indicating the displacement of the first surface 11a of the object 11 (step S23, acquisition step). Steps S22 and S23 will be described in detail. In steps S22 and S23, first, the control unit 6 controls the drive units 4 and 5 to move the laser irradiation unit 3 along the X direction and Y direction, and position the laser irradiation unit 3 on line A. As described above, the displacement sensor 9 moves integrally with the laser irradiation unit 3. Therefore, moving the laser irradiation unit 3 means moving the displacement sensor 9.

Next, in steps S22 and S23, the control unit 6 controls the drive units 4 and 5 to relatively move the laser irradiation unit 3 along the line A, while controlling the displacement sensor 9 to irradiate the measurement laser light LA toward the object 11 (perform tracing). As a result, the control unit 6 acquires the displacement sensor voltage VD output from the displacement sensor 9 in response to the reflected light LR of the measurement laser light LA as displacement information indicating the displacement of the first surface 11a of the object 11. In other words, the control unit 6 executes an acquisition process to acquire displacement information indicating the displacement of the first surface 11a in the Z direction.

As a result, displacement information along line A of the first surface 11a of the object 11 is acquired. That is, here, the control unit 6 continuously measures the displacement of the first surface 11a using the displacement sensor 9 and acquires the displacement information. As a result, the control unit 6 obtains the distribution of the displacement of the first surface 11a along line A. Therefore, the control unit 6 makes it possible to select the position on the first surface 11a where the displacement changes along line A at which to perform the height setting.

In the next step, the control unit 6 controls the driving units 4 and 5 based on the displacement information to move the laser irradiation unit 3 in the X and Y directions, thereby disposing the laser irradiation unit 3 at a first position where the displacement of the first surface 11a is the center value of the range of displacement of the first surface 11a (step S24). Note that the first position is a position in the XY plane including the X and Y directions.

Next, similar to step S13, the height is set at the first position (step S25). More specifically, in step S25, the control unit 6 drives the drive units 4 and 5 so that the measurement laser light LA is focused on the first surface 11a of the object 11 while the laser irradiation unit 3 is disposed at the first position, moves the laser irradiation unit 3 relatively along the Z direction, and moves the focal point of the measurement laser light LA relative to the object 11 along the Z direction. Then, the control unit 6 acquires the height set voltage, which is the value of the displacement sensor voltage VD when the focal point of the measurement laser light LA coincides with the first surface 11a.

Next, similarly to step S14, a reference voltage for the drive voltage of actuator 8 is set (step S26). In this step S26, the control unit 6 associates the reference voltage of actuator 8 with the height set voltage acquired in step S25. More specifically, for example, the reference voltage is set so that when the displacement sensor voltage VD of displacement sensor 9 is the height set voltage, the reference voltage is applied to actuator 8 (i.e., the amount of expansion and contraction of actuator 8 corresponds to the reference voltage).

As a result, as shown in FIG. 9, the movable range RA of the actuator 8 is set with the displacement of the first surface 11a at the first position Pe (the Z-axis height, the central value of the displacement) as the central value Ao. Therefore, during follow-up machining, the actuator 8 is driven both below the central value Ao of the movable range RA (e.g. the extending side) and above the central value Ao of the movable range RA (e.g. the contracting side), and the range in which the actuator 8 is stopped and follow-up machining becomes difficult is reduced (here it becomes 0).

In the above steps S24 to S26, the first position where the height is set is the position where the displacement of the first surface 11a is the central value of the range of displacement of the first surface 11a. However, the first position does not have to be the central value position, and can be a position where the displacement is a specific value of a central range, which is a part of the range that includes the central value of the displacement of the first surface 11a. However, the central range here is a range that at least excludes the upper and lower limits of the displacement of the first surface 11a.

The control unit 6 therefore executes an association process in steps S24 to S26 above to associate a specific value of a central range, which is a part of the range of displacement including the central value of the displacement (here, the height set voltage value at the first position, which is the specific value), with the reference voltage of the drive voltage of the actuator 8, based on the displacement information. In addition, in the laser processing method according to this embodiment, an association process is executed in steps S24 to S26 above to associate a specific value of a central range, which is a part of the range of displacement including the central value of the displacement, with the reference voltage of the drive voltage of the actuator 8, based on the displacement information. The above example is an example in which the specific value is the central value.

Furthermore, in the above steps S24 to S26, the control unit 6 executes the following association processes: a first process, which controls the drive units 4 and 5 to move the laser irradiation unit 3 to a first position where the displacement of the first surface 11a is a value in the central range; a second process, which controls the drive units 4 and 5 to relatively move the laser irradiation unit 3 along the Z direction after the first process so that the measurement laser light LA is focused on the first surface 11a; and a third process, which associates the measured value of the displacement (height set voltage) of the displacement sensor 9 when the measurement laser light LA is focused on the first surface 11a with the reference voltage of the actuator 8 after the second process.

In the next step, the laser irradiation unit 3 is moved to line A (step S27). More specifically, in step S27, the control unit 6 controls the driving units 4 and 5 to move the laser irradiation unit 3 along the X direction and the Y direction, and position the laser irradiation unit 3 on line A.

After that, the actual laser processing is performed (step S28, processing step). That is, the control unit 6 drives the actuator 8 around the reference voltage, thereby relatively moving the focal point C along the line A along the X direction while adjusting the position of the focal point C of the laser light L in the Z direction according to the displacement of the first surface 11a, and performs a processing process to perform laser processing of the object 11 along the line A. At this time, the control unit 6 can drive the actuator 8 according to the displacement at the processing position on the line A based on the displacement information already acquired and the processing position on the line A.

As described above, in the laser processing device 1 and the laser processing method according to the present embodiment, first, displacement information indicating the displacement of the first surface 11a of the object 11 in the Z direction is acquired. Then, based on the acquired displacement information, a specific value of a central range, which is a part of the range of displacement including the central value of the displacement of the first surface 11a of the object 11, is associated with the reference voltage of the drive voltage of the actuator 8. Then, by driving the actuator 8 around the reference voltage, the position of the focal point C of the laser light L in the Z direction is adjusted according to the displacement of the first surface 11a of the object 11, while the focal point C is relatively moved along the line A along the X direction, and the laser processing (follow-up processing) of the object 11 is performed along the line A. For this reason, during the follow-up processing, it is possible to avoid using only the lower side or the upper side than the center of the movable range of the actuator 8. Therefore, it is possible to suppress the possible range of follow-up processing from being narrowed, compared to the case where the displacement amount (Z-axis height) of the first surface 11a at the center of the object 11 is uniformly associated with the reference voltage of the actuator 8.

In addition, in the laser processing device 1 and laser processing method according to this embodiment, the specific value may be the center value of the displacement of the first surface 11a. In this case, the lower and upper sides of the center of the movable range RA of the actuator 8 are used equally in the follow-up processing. This reliably prevents the possible range of follow-up processing from being narrowed.

The laser processing device 1 according to this embodiment is also provided with a displacement sensor 9 that is arranged to move integrally with the laser irradiation unit 3 and emits measurement laser light LA toward the object 11 and inputs reflected light LR of the measurement laser light LA to measure the displacement of the first surface 11a and obtain displacement information. Therefore, it is possible to obtain displacement information indicating the displacement of the first surface 11a of the object 11 using the displacement sensor 9.

In addition, in the laser processing device 1 according to this embodiment, the control unit 6 uses the displacement sensor 9 to continuously measure the displacement of the first surface 11a and acquire displacement information. Therefore, it is possible to acquire displacement information that is more consistent with the actual displacement of the first surface 11a of the object 11.

Further, the laser processing apparatus 1 according to the present embodiment includes the driving units 4 and 5 for moving the laser irradiation unit 3 and the displacement sensor 9 relative to the object 11 along the Z direction. In the association process, the control unit 6 executes a first process of moving the laser irradiation unit 3 and the displacement sensor 9 to a first position where the displacement of the first surface 11a becomes a specific value by controlling the driving units 4 and 5, a second process of moving the laser irradiation unit 3 and the displacement sensor 9 relative to the first surface 11a by controlling the driving units 4 and 5 after the first process, and a third process of associating the measured value (height set voltage value) of the displacement of the displacement sensor 9 when the measurement laser light LA is focused on the first surface 11a with a reference voltage after the second process. In this way, in the association process, the actual measured value of the displacement of the first surface 11a of the object 11 can be associated with the reference voltage of the drive voltage of the actuator 8 as a specific value.
[Second embodiment]

Next, a second embodiment of the laser processing device and the laser processing method will be described. Here, the thickness of the object 11 is constant in the central portion including the center 11c as shown in FIG. 10(a), and gradually decreases at a constant rate from the central portion toward the outer edge. In other words, the displacement amount (Z-axis height) of the first surface 11a of the object 11 is constant in the central portion and gradually decreases from the central portion toward the outer edge. Also, line A is set in a straight line so as to run from one outer edge through the central portion to the other outer edge.

For such an object 11, the height may be set at the center 11c to obtain a height set voltage, and the height set voltage may be correlated with the reference voltage of the actuator 8. In this case, the center value Ao of the movable range RA of the actuator 8 is set to the upper limit of the displacement of the first surface 11a. Therefore, in this case, when attempting to perform tracking processing along the line A, the actuator 8 will be driven only below the center value Ao of the movable range RA (e.g., the stretching side), and the displacement sensor voltage VD will exceed the movable range RA of the actuator 8 in the range from one outer edge of the object 11 to the distance Pf, and from the distance Pg to the other outer edge of the object 11, making tracking processing difficult.

In contrast, in this embodiment, tracking processing is performed as follows. FIG. 11 is a flowchart showing the laser processing method according to the second embodiment. As shown in FIG. 11, in the laser processing method according to this embodiment, first, the control unit 6 acquires displacement information indicating the displacement of the first surface 11a of the object 11 (step S31). The control unit 6 can also acquire the displacement information by tracing as in the first embodiment, but in this embodiment, it is assumed that the shape of the object 11 is known and the displacement information is acquired by external input.

Next, alignment is performed in the same manner as in step S21 (step S32). Next, the laser irradiation unit 3 is moved onto the center 11c of the object 11 (step S33). More specifically, in this step S33, the control unit 6 controls the drive units 4 and 5 to move the laser irradiation unit 3 relative to the object 11 in the X and Y directions, thereby moving the laser irradiation unit 3 onto the center 11c of the object 11. As described above, the center 11c of the object 11 is the second position where the displacement of the first surface 11a becomes the upper limit value.

Next, similar to step S25, the height is set at the second position (step S34). More specifically, in step S34, the control unit 6 drives the drive units 4 and 5 so that the measurement laser light LA is focused on the first surface 11a of the object 11 while the laser irradiation unit 3 is disposed at the second position, and moves the laser irradiation unit 3 relatively along the Z direction, thereby moving the focal point of the measurement laser light LA relative to the object 11 along the Z direction. Then, the control unit 6 acquires a height set voltage, which is the value of the displacement sensor voltage VD when the focal point of the measurement laser light LA coincides with the first surface 11a.

Next, similar to step S26, a reference voltage for the drive voltage of the actuator 8 is set (step S35). That is, in this step S35, the control unit 6 associates the reference voltage of the actuator 8 with the height set voltage acquired in step S34. This causes the actuator 8 to be driven around the upper limit of the displacement of the first surface 11a. Therefore, in the next step, the control unit 6 offsets the movable range RA (step S36).

More specifically, in step S36, the control unit 6 controls the drive units 4 and 5 to relatively move the laser irradiation unit 3 along the Z direction. Here, the control unit 6 relatively moves the laser irradiation unit 3 along the Z direction so that the focal point of the measurement laser light LA moves toward the second surface 11b rather than the first surface 11a. In this state, the control unit 6 acquires a displacement sensor voltage VD. This displacement sensor voltage VD is an offset value Ve that is offset downward from the height set voltage Vo acquired in step S34, as shown in FIG. 12.

The control unit 6 then associates the offset value Ve with the reference voltage value of the actuator 8. That is, the reference voltage is set so that when the displacement sensor voltage VD of the displacement sensor 9 is the offset value Ve, the reference voltage is applied to the actuator 8 (that is, the amount of expansion and contraction of the actuator 8 corresponds to the reference voltage). The offset value Ve is a value that corresponds to the median value of the displacement of the first surface 11a of the object 11, and is, for example, 1/2 the value of the height set voltage Vo.

In this way, the control unit 6 executes an association process that associates a specific value of a central range that is a part of the range of displacement including the central value of the displacement of the first surface 11a (here, the offset value Ve of the height set voltage Vo) with the reference voltage of the drive voltage of the actuator 8 based on the displacement information throughout the above steps S34 to S36. Also, in the laser processing method according to this embodiment, an association process that associates a specific value of a central range that is a part of the range of displacement including the central value of the displacement with the reference voltage of the drive voltage of the actuator 8 based on the displacement information throughout the above steps S34 to S36. The above example is an example in which the specific value is the central value.

Furthermore, in the above steps S34 to S36, the control unit 6 executes the following association processes: a fourth process in which the drive units 4 and 5 are used to move the laser irradiation unit 3 to a second position where the displacement of the first surface 11a is at its upper limit; a fifth process in which, after the fourth process, the drive units 4 and 5 are used to relatively move the laser irradiation unit 3 along the Z direction at the second position so that the measurement laser light LA is focused on the first surface 11a; and a sixth process in which, after the fifth process, the offset amount is set so that the offset value (the displacement value corresponding to the offset value Ve) obtained by adding the offset amount to the displacement measurement value (height set voltage Vo) of the displacement sensor 9 when the measurement laser light LA is focused on the first surface 11a is included in the central range, and the offset value Ve is associated with the reference voltage as a specific value.

As a result, as shown in FIG. 12, the movable range RA of the actuator 8 is offset. Therefore, during follow-up processing along the line A, the actuator 8 is driven both below the center value Ao of the movable range RA (e.g., the extending side) and above the center value Ao of the movable range RA (e.g., the contracting side), and the range in which the actuator 8 is stopped and follow-up processing becomes difficult is reduced (here, becomes 0).

In the next step, the control unit 6 moves the laser irradiation unit 3 to the line A (step S37), similar to step S27. Then, similar to step S28, laser processing is actually performed (step S38, processing step). That is, the control unit 6 drives the actuator 8 around the reference voltage, thereby relatively moving the focal point C along the line A along the X direction while adjusting the position of the focal point C of the laser light L in the Z direction according to the displacement of the first surface 11a, and performs a processing process to perform laser processing of the object 11 along the line A. At this time, the control unit 6 can drive the actuator 8 according to the displacement at the processing position based on the already acquired displacement information and the processing position on the line A.

As described above, in this embodiment, as in the first embodiment, it is possible to prevent the possible range of tracking processing from being narrowed. Furthermore, in this embodiment, in the association process, an offset value (a value corresponding to the offset value Ve) offset from the actual measured value (height set voltage Vo) of the displacement of the first surface 11a of the object 11 can be set as a specific value and associated with the reference voltage of the drive voltage of the actuator 8.

In the above example, the second position where the height is set is the position where the displacement of the first surface 11a is the upper limit. However, the second position may be the position where the displacement of the first surface 11a is the lower limit, depending on the shape of the object 11 and the setting of the displacement standard.

Furthermore, when the displacement sensor 9 is configured coaxially with the laser light L, the displacement sensor voltage VD may be nonlinear with respect to changes in the Z-axis height of the first surface 11a. The above-mentioned step S36 is an example of a case where the displacement sensor voltage VD is nonlinear in this way. In contrast, when the displacement sensor 9 is configured on a different axis from the laser light L, for example, and the characteristic of the displacement sensor voltage VD with respect to the Z-axis height is known, such as when the displacement sensor 9 is configured on a different axis from the laser light L and the displacement sensor voltage VD is linear with respect to changes in the Z-axis height of the first surface 11a, the offset value Ve can be found in step S36 based on the known characteristic of the displacement sensor voltage VD without actually moving the laser irradiation unit 3 in the Z direction.
[Third embodiment]

Next, a third embodiment of the laser processing device and the laser processing method will be described. FIG. 13 is a flowchart showing the laser processing method according to the third embodiment. Note that, in this example, a number of straight lines A that extend parallel to each other when viewed from the Z direction are set on the target object 11.

As shown in FIG. 13, steps S41 to S48 are performed here as in the first embodiment. The contents of steps S41 to S48 are the same as steps S21 to S28, respectively. However, in step S42, one of the multiple lines A is traced in the same way as in step S22, to obtain displacement information of the first surface 11a of the object 11 along the one line A (step S43). In step S45, the height is set in the same way as in step S25 based on the displacement information on the one line A, and in step S46, the reference voltage is set in the same way as in step S26. Then, in step S47, the laser irradiation unit 3 is moved onto the one line A in the same way as in step S27, and in step S48, laser processing is performed on the one line A in the same way as in step S28.

Then, the control unit 6 judges whether the line A (the line A for which processing has just been completed) is the last line A of the multiple lines A (step S49). If the result of the judgment in step S49 is that the line A is the last line A (step S49: YES), the process ends. On the other hand, if the result of the judgment in step S49 is that the line A is not the last line A (step S49: NO), the control unit 6 controls the drive units 4 and 5 to relatively move the laser irradiation unit 3 in the X and Y directions, and moves the laser irradiation unit 3 to another line A (step S50).

Then, the process returns to step S42, and steps S42 and after are performed again for the other line A. In this manner, in this embodiment, displacement information is acquired, a height is set, and a reference voltage is set for each of the multiple lines A. Therefore, in addition to the same effects as in the first embodiment, more suitable follow-up processing is possible for the displacement of the first surface 11a of the target object 11 along each line A.
[Fourth embodiment]

In contrast, in the fourth embodiment shown in FIG. 14, if the result of the judgment in step S49 is that the line A is not the last line A (step S49: NO), the control unit 6 controls the driving units 4 and 5 to relatively move the laser irradiation unit 3 in the X direction and the Y direction, and moves the laser irradiation unit 3 to another line A (step S50). Then, the process returns to step S48, and step S48 is performed again for the other line A. That is, in this embodiment, the displacement information, height set voltage, and reference voltage acquired by tracing the line A are used to perform follow-up processing of the other line A. Therefore, according to this embodiment, in addition to the same effects as the first embodiment, the time required for acquiring the displacement information and the height set voltage and setting the reference voltage can be shortened.
[Fifth embodiment]

Next, a laser processing apparatus and a laser processing method according to the fifth embodiment will be described. FIG. 15 is a flowchart showing the laser processing method according to the fifth embodiment. As shown in FIG. 15, steps S61 to S63 are carried out here, as in the first embodiment. The contents of steps S61 to S63 are the same as steps S21 to S23, respectively.

Then, it is determined whether the displacement of the first surface 11a of the object 11 exceeds the movable range RA of the actuator 8 (step S64). More specifically, in this step S64, the control unit 6 executes a determination process to determine whether the movable range RA of the actuator 8 exceeds the displacement based on a comparison between the displacement information (displacement sensor voltage VD) and the movable range RA of the actuator 8.

Then, if the result of the determination in step S64 is that the displacement of the first surface 11a of the target object 11 exceeds the movable range RA of the actuator 8 (step S64: NO), the control unit 6 executes a notification process to notify that effect (step S70). As an example of the notification, the control unit 6 can display a warning on the input receiving unit. Then, the process ends. On the other hand, if the result of the determination in step S64 is that the displacement does not exceed the movable range RA (step S64: YES), steps S65 to S69 are performed. Steps S65 to S69 are the same as steps S24 to S28 in the first embodiment. Thus, according to this embodiment, in addition to the same effects as the first embodiment, it is possible to recognize the case where the displacement of the first surface 11a of the target object 11 exceeds the movable range RA of the actuator 8.
Sixth Embodiment

Next, a laser processing apparatus and a laser processing method according to the sixth embodiment will be described. As shown in FIG. 16, this embodiment is intended to deal with the case where the displacement (displacement sensor voltage VD) of the first surface 11a of the object 11 greatly exceeds the movable range RA of the actuator 8. In this embodiment, as shown in FIG. 17, steps S71 to S74 are performed. Steps S71 to S74 are similar to steps S61 to S64 in the fifth embodiment. Then, if the result of the determination in step S74 is that the displacement of the first surface 11a of the object 11 does not exceed the movable range RA of the actuator 8, steps S75 to S79 are performed in the same manner as steps S24 to S28 in the first embodiment.

On the other hand, if the result of the determination in step S74 is that the displacement of the first surface 11a of the object 11 exceeds the movable range RA of the actuator 8 (step S74: NO), as shown in FIG. 18, a lower limit region including the position on line A where the displacement of the first surface 11a is at its lower limit, that is, the position where the displacement sensor voltage VD and the Z-axis height of the first surface 11a are at their lower limits, is extracted (step S81). Here, as shown in FIG. 16, the control unit 6 extracts a part of the line A including the position Pm where the displacement sensor voltage VD is at its lower limit, and where the displacement is included in the movable range RA when the Z-axis height of the first surface 11a at position Pm is set as the lower limit of the movable range RA, as the lower limit region. Here, the lower limit region is the region up to position Ph on line A.

Then, the control unit 6 performs height setting, reference voltage setting, and follow-up processing on the extracted lower limit region in steps S82 to S85. The specific content of steps S82 to S85 is similar to steps S25 to S28 in the first embodiment, except that the target is the lower limit region rather than the entire line A. As an example, in step S82, a height is set at a first position within the lower limit region where the displacement of the first surface 11a is the median value of the range of displacement of the first surface 11a. As a result, only the lower limit region of line A is processed.

Next, as shown in FIG. 19, another lower limit area is extracted from the unprocessed area of line A (step S86). That is, in step S86, the control unit 6 extracts another lower limit area from the unprocessed area of line A, including a position where the displacement of the first surface 11a is at its lower limit, that is, a position where the displacement sensor voltage VD and the Z-axis height of the first surface 11a are at their lower limits. Here, as shown in FIG. 16, the control unit 6 extracts the remaining area of line A, which includes a position Ph in the unprocessed area where the displacement sensor voltage VD is at its lower limit, and where the displacement is included in the movable range RA when the Z-axis height of the first surface 11a at position Ph is set to the lower limit of the movable range RA, as the other lower limit area. Here, the other lower limit area is the area of line A after position Ph.

Then, the control unit 6 performs height setting, reference voltage setting, and follow-up processing on the extracted other lower limit region in steps S87 to S89. The specific content of these steps S87 to S89 is similar to steps S25 to S28 in the first embodiment, except that the target is the other lower limit region rather than the entire line A. As an example, in step S86, a height is set in the other lower limit region at a first position where the displacement of the first surface 11a is the central value of the range of displacement of the first surface 11a. In this way, the other lower limit region of line A is further processed.

Then, the control unit 6 judges whether or not processing of all areas of line A (i.e., the entirety of line A) has been completed (step S90). If the result of the judgment in step S90 is that processing of all areas of line A has been completed (step S90: YES), the process ends. On the other hand, if the result of the judgment in step S90 is that processing of all areas of line A has not been completed (step S90: NO), the steps from step S86 onwards are carried out again.

As described above, in this embodiment, one line A is divided into a plurality of regions included in the movable range RA of the actuator 8, and follow-up processing is performed. That is, in this embodiment, when the result of the judgment (judgment process) in step S74 is that the displacement of the first surface 11a exceeds the movable range RA of the actuator 8, the control unit 6 divides the line A into a plurality of parts (a plurality of lower limit regions) so that the displacement of the first surface 11a is included in the movable range RA, and performs an association process and a processing process for each part. Therefore, according to this embodiment, the possible range of follow-up processing is expanded (in the above example, follow-up processing is possible in all regions of the first surface 11a).
[Modification]

The above embodiment describes one aspect of the present invention. Therefore, the present invention is not limited to the above embodiment and may be modified as desired.

For example, in the above embodiment, the control unit 6 continuously measures the displacement of the first surface 11a using the displacement sensor 9 to obtain the displacement information (displacement sensor voltage VD). However, as shown in FIG. 20(a), the control unit 6 may obtain the displacement information by discretely measuring the displacement at multiple locations K on the first surface 11a of the object 11 using the displacement sensor 9. In this case, the control unit 6 can associate the median value of each of the displacements at the multiple locations K (each of the displacement sensor voltages VD corresponding to the displacement) with the reference voltage of the actuator 8.

In addition, as shown in FIG. 20(b), the control unit 6 may use the displacement sensor 9 to measure the displacement of the first surface 11a in a spiral shape to obtain displacement information, regardless of the shape of the line A. In this case, based on the obtained displacement information, the median value of the displacement (the displacement sensor voltage VD corresponding to the displacement) can be associated with the reference voltage of the actuator 8.

Furthermore, in the above example, as shown in FIG. 21(a), the position of the movable range RA of the actuator 8 that corresponds to the reference voltage associated with the height set voltage is set to the central value Ao. In other words, the amount of expansion and contraction of the actuator 8 when a reference voltage equivalent to the height set voltage is applied to the actuator 8 is set to the central value Ao of the movable range RA. In this case, the range Rc from the central value Ao to the lower limit Ac of the movable range RA is equivalent to the range Re from the central value Ao to the upper limit Ae of the movable range RA.

However, as shown in FIG. 21B, a value A1 offset from the center value Ao of the movable range RA of the actuator 8 toward the upper limit value Ae (or lower limit value Ac) of the movable range RA may be associated with the reference voltage. In this case, the range Rc becomes wider (or narrower) than the range Re. In this case, the control unit 6 drives the actuator 8 in the movable range RA including the reference voltage after the association process, thereby relatively moving the focal point C along the line A along the X direction while adjusting the position of the focal point C of the laser light L in the Z direction according to the displacement of the first surface 11a, and performing a processing process to perform laser processing of the object 11 along the line A. In this case, the reference voltage is offset with respect to the center of the movable range RA.

Furthermore, the above first to sixth embodiments can be combined in any way. For example, the third and fourth embodiments give an example in which multiple straight lines A are set on the object 11, and follow-up processing is performed across the multiple lines A. In contrast, for example, in the first embodiment, multiple circular lines A are set on the object 11, and the steps of the third and fourth embodiments can be applied so that follow-up processing is performed across the multiple circular lines A.

1...laser processing device, 2...stage (supporting part), 4, 5...drive part (first moving part, second moving part), 6...control part, 8...actuator, 9...displacement sensor, 11...object, 11a...first surface, 11b...second surface, 11c...center, 33...collecting lens, A...line, L...laser light, LA...measurement laser light (measurement light), LR...reflected light.

Claims (9)

A support portion for supporting an object, the support portion including a first surface and a second surface opposite to the first surface;
a laser irradiation unit for irradiating the object supported by the support unit with laser light from the first surface side via a condenser lens;
an actuator for driving the condenser lens along a Z direction from the second surface toward the first surface;
a first moving unit for moving at least one of the support unit and the laser irradiation unit such that a focal point of the laser light moves relative to the object along an X direction intersecting the Z direction;
a control unit that controls at least the actuator, the laser irradiation unit, and the first moving unit, and irradiates the object with the laser light to perform laser processing of the object;
Equipped with
The control unit is
an acquisition process for acquiring displacement information indicating a displacement of the first surface in the Z direction;
an association process for associating a specific value of a central range, which is a part of the range of the displacement including a central value of the displacement, with a reference voltage of a drive voltage of the actuator, based on the displacement information after the acquisition process;
after the association process, a processing process is executed in which the actuator is driven around the reference voltage, thereby relatively moving the focal point along a line along the X direction while adjusting a position of the focal point of the laser light in the Z direction according to the displacement, and laser processing of the object is performed along the line ;
the control unit executes a determination process between the acquisition process and the association process to determine whether or not the displacement exceeds a movable range of the actuator;
when the result of the determination process indicates that the displacement exceeds the movable range, the control unit divides the line into a plurality of portions so that the displacement is included in the movable range, and executes the association process and the processing process for each of the portions.
Laser processing equipment. The specific value is a median value of the displacement.
The laser processing device according to claim 1. a displacement sensor that is provided to move integrally with the laser irradiation unit, and that emits measurement light toward the object and receives reflected light of the measurement light to measure the displacement of the first surface and acquire the displacement information;
3. The laser processing apparatus according to claim 1 or 2. The control unit continuously measures the displacement using the displacement sensor to obtain the displacement information.
The laser processing apparatus according to claim 3. the control unit measures the displacement discretely at a plurality of points in the first plane using the displacement sensor to acquire the displacement information.
The laser processing apparatus according to claim 3. a second moving unit for moving the laser irradiation unit and the displacement sensor relative to the object along the Z direction;
The control unit, in the association process,
a first process of moving the laser irradiation unit and the displacement sensor to a first position where the displacement of the first surface becomes the specific value by controlling the first movement unit;
a second process of relatively moving the laser irradiation unit and the displacement sensor along the Z direction by controlling the second moving unit after the first process so that the measurement light is focused on the first surface;
a third process of associating a measurement value of the displacement of the displacement sensor when the measurement light is focused on the first surface with the reference voltage after the second process;
Execute
The laser processing device according to any one of claims 3 to 5. a second moving unit for moving the laser irradiation unit and the displacement sensor relative to the object along the Z direction;
The control unit, in the association process,
a fourth process of controlling the first moving unit to move the laser irradiation unit and the displacement sensor to a second position where the displacement of the first surface becomes a lower limit value or an upper limit value;
a fifth process of relatively moving the laser irradiation unit and the displacement sensor along the Z direction by controlling the second moving unit after the fourth process so that the measurement light is focused on the first surface;
a sixth process of, after the fifth process, setting an offset value obtained by adding an offset amount to a measurement value of the displacement of the displacement sensor when the measurement light is focused on the first surface so that the offset value is included in the central range, and associating the offset value with the reference voltage as the specific value;
Execute
The laser processing device according to any one of claims 3 to 5. the control unit executes, between the acquisition process and the association process, a notification process for notifying a result of the determination process that the displacement exceeds the movable range;
the control unit executes the association process and the processing process when a result of the determination process indicates that the displacement does not exceed the movable range.
The laser processing device according to any one of claims 1 to 7. A laser processing method for performing laser processing by controlling at least a laser irradiation unit for irradiating a laser beam from a first surface side via a condensing lens to an object supported by a support unit, the object including a first surface and a second surface opposite to the first surface, an actuator for driving the condensing lens along a Z direction from the second surface toward the first surface, and a first moving unit for moving at least one of the support unit and the laser irradiation unit such that a focal point of the laser beam moves relative to the object along an X direction intersecting the Z direction,
acquiring displacement information indicating a displacement of the first surface in the Z direction;
an associating step of associating, after the acquiring step, a specific value of a central range, which is a part of the range of the displacement including a central value of the displacement, with a reference voltage of a drive voltage of the actuator, based on the displacement information;
a processing step of, after the associating step, driving the actuator around the reference voltage to relatively move the focal point along a line along the X direction while adjusting a position of the focal point of the laser light in the Z direction according to the displacement, and performing laser processing of the object along the line,
determining whether or not the displacement exceeds a movable range of the actuator between the acquiring step and the associating step;
When the result of the determination indicates that the displacement exceeds the movable range, the line is divided into a plurality of portions so that the displacement is included in the movable range, and the associating step and the processing step are performed for each of the portions.
Laser processing method.

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