JP7548858B2 - Object processing method and object processing system - Google Patents

Description

The present invention relates to an object processing method and an object processing system.

A method for processing an object is known that includes a grinding step in which a portion of the object from the surface to the intended grinding position is ground, and a laser processing step in which, prior to the grinding step, laser light is irradiated along a line onto the object via a focusing lens to form a modified region along the line inside the object between the surface and the intended grinding position (see, for example, Patent Document 1). In the laser processing step of such an object processing method, the focusing position of the laser light focused inside the object is moved along the line, and the focusing position is made to follow the displacement of the laser light incident surface.

JP 2009-131942 A

In the above-mentioned technology, when the focusing position of the laser light (hereinafter also simply referred to as the "focusing position") is made to follow the laser light incident surface, the focusing position may be displaced locally and significantly in the optical axis direction of the focusing lens due to, for example, vibration, unevenness, changes in reflectance, and roughness of the object. In this case, a modified region may be formed in the part of the object that goes beyond the intended grinding position on the side opposite the surface side (i.e., the part that is not removed by grinding), and the modified region may remain in the object after grinding. As a result, the quality of the object after grinding will deteriorate. Note that, below, going beyond (moving to) the side opposite the surface side will also be simply referred to as "going beyond."

The present invention aims to provide an object processing method and object processing system that can prevent modified regions from remaining on the object after grinding.

The method for processing an object according to the present invention includes a grinding step for grinding a portion of the object from the surface to the intended grinding position, and a laser processing step for irradiating the object with laser light via a focusing lens along a line prior to the grinding step to form one or more rows of modified regions along the line inside the object between the surface and the intended grinding position. The laser processing step includes a data acquisition step for acquiring measurement data relating to the displacement of the laser light incident surface of the object, a focusing step for moving the focusing position of the laser light along the line while causing the focusing position to follow the displacement of the laser light incident surface based on the measurement data, and a monitoring step for monitoring whether the modified region formed by focusing the laser light to the focusing position exceeds an error detection position, which is determined between the intended grinding position and the intended grinding position, closest to the intended grinding position in the optical axis direction of the focusing lens, toward the intended grinding position when the focusing position is caused to follow the displacement of the laser light incident surface based on the measurement data.

In this method of processing an object, when the focusing position is made to follow the displacement of the laser light incident surface, it is monitored whether the modified region formed by focusing the light at the focusing position exceeds an error detection position set on the surface side of the intended grinding position. Therefore, if it is determined as a result of monitoring that the modified region exceeds the error detection position, it is possible to take measures to prevent the modified region from exceeding the intended grinding position, for example, by preventing the focusing position from approaching the intended grinding position during that time. In other words, it is possible to prevent the modified region from remaining on the object after grinding.

In the object processing method according to the present invention, the monitoring step may calculate an amount of meandering corresponding to the amount of deviation in the optical axis direction when the position of the modified region formed by focusing the laser light on the focusing position deviates from the intended position of the modified region when the focusing position is made to follow the displacement of the laser light incident surface based on the measurement data, and monitor whether the amount of meandering exceeds the distance in the optical axis direction from the intended position to the error detection position. In this case, the amount of meandering can be used to monitor whether the modified region moves beyond the error detection position toward the intended grinding position.

In the object processing method according to the present invention, the measurement data may be a voltage value corresponding to the reflected light acquired by a sensor that receives the reflected light of the distance measuring laser light reflected by the laser light incident surface. In this case, it is possible to monitor whether the modified region extends beyond the error detection position toward the intended grinding position by using the sensor that receives the reflected light of the distance measuring laser light reflected by the laser light incident surface.

In the object processing method according to the present invention, the monitoring step may include a step of performing feedback control to move the focusing lens in the optical axis direction so that the measurement data becomes the target voltage value, thereby causing the focusing position to follow the displacement of the laser light incident surface, and a step of monitoring whether the modified region extends beyond the error detection position toward the intended grinding position based on the difference between the post-feedback voltage value, which is the voltage value acquired by the sensor as a result of the feedback control, and the target voltage value. In this case, it is possible to effectively use a sensor that receives the reflected light of the ranging laser light reflected by the laser light incident surface to monitor whether the modified region extends beyond the error detection position toward the intended grinding position.

In the object processing method according to the present invention, the laser processing step may include an input step of inputting the error detection position via the input unit. In this case, the user can set the desired error detection position via the input unit.

In the object processing method according to the present invention, in the focusing step, if the focusing position in the direction along the line is in an error region when the monitoring step determines that the modified region has exceeded the error detection position toward the intended grinding position, the position of the focusing lens in the optical axis direction may be fixed. In this case, specific measures can be taken to prevent the modified region from exceeding the intended grinding position.

In the object processing method according to the present invention, in the focusing step, if the focusing position in the direction along the line is in an error region when the monitoring step determines that the modified region has exceeded the error detection position toward the intended grinding position, the control parameters related to tracking of the focusing position may be changed to slow down the tracking. In this case, specific measures can be taken to prevent the modified region from exceeding the intended grinding position.

In the object processing method according to the present invention, in the focusing step, if the focusing position in the direction along the line is in an error area when the monitoring step determines that the modified area has exceeded the error detection position toward the intended grinding position, irradiation of the laser light to the object may be stopped. In this case, specific measures can be taken to prevent the modified area from exceeding the intended grinding position.

In the object processing method according to the present invention, the monitoring step may display an error message on the display unit if it is determined that the modified area extends beyond the error detection position toward the intended grinding position. In this case, the error message displayed on the display unit can inform the user, for example, that there is a high possibility that the modified area will remain in the object after grinding.

The object processing system according to the present invention comprises a grinding device that grinds a portion of the object from the surface to the intended grinding position, and a laser processing device that irradiates the object with laser light via a focusing lens along a line before grinding by the grinding device, and forms one or more rows of modified regions along the line between the surface inside the object and the intended grinding position. The laser processing device comprises a support unit that supports the object, an irradiation unit that irradiates the object with laser light via a focusing lens, a movement mechanism that moves at least one of the support unit and the irradiation unit so that the focused position of the laser light moves, an actuator that drives the focusing lens along the optical axis direction of the focusing lens, a measurement data acquisition unit that acquires measurement data regarding the displacement of the laser light incident surface on which the laser light is incident on the object, the irradiation unit, the movement mechanism, and and a control unit that controls the actuator, and the control unit executes a focusing process in which at least one of the support unit and the irradiating unit is moved along the line so that the focusing position of the laser light moves along the line, while at least one of the support unit and the condensing lens is moved along the optical axis direction so that the focusing position follows the displacement of the laser light incident surface based on the measurement data, and a monitoring process in which, when at least one of the support unit and the condensing lens is moved along the optical axis direction so that the focusing position follows the displacement of the laser light incident surface based on the measurement data, a monitoring process is executed in which, in the optical axis direction, a modified region formed by focusing the laser light to the focusing position exceeds an error detection position defined between the planned formation position of the modified region closest to the planned grinding position and the planned grinding position, toward the planned grinding position.

In this object processing system, when the focusing position is made to follow the displacement of the laser light incident surface, it monitors whether the modified region formed by focusing the light at the focusing position exceeds the error detection position on the surface side of the planned grinding position. Therefore, if it is determined as a result of monitoring that the modified region exceeds the error detection position, it is possible to take measures to prevent the modified region from exceeding the planned grinding position, for example, by preventing the focusing position from approaching the planned grinding position during that time. Therefore, it is possible to prevent the modified region from remaining on the object after grinding.

The present invention makes it possible to provide an object processing method and object processing system that can monitor the object after grinding to ensure that no modified areas remain.

FIG. 1 is a configuration diagram showing an object processing system according to an embodiment. FIG. 2 is a diagram showing the configuration of the laser processing head of FIG. Fig. 3(a) is a diagram showing an example of an input/output screen of the GUI of the laser processing apparatus of Fig. 1. Fig. 3(b) is a diagram showing an example of an input/output screen of the GUI of the grinding apparatus of Fig. 1. FIG. 4 is a cross-sectional view of an object for explaining an error detection position. Fig. 5(a) is a plan view showing an object for explaining a method for processing an object according to an embodiment, and Fig. 5(b) is a cross-sectional view showing the object of Fig. 5(a). Fig. 6(a) is a plan view showing a continuation of Fig. 5(a) in the method for machining an object according to the embodiment, and Fig. 6(b) is a cross-sectional view showing the object in Fig. 6(a). Fig. 7(a) is a plan view showing a continuation of Fig. 6(a) in the method for processing an object according to the embodiment, and Fig. 7(b) is a cross-sectional view showing the object in Fig. 7(a). FIG. 8A is a cross-sectional view showing a continuation of FIG. 7A in the object processing method according to the embodiment. FIG. 9 is a flowchart showing the trimming process according to the embodiment. FIG. 10 is a graph showing an example of a monitoring result of the monitoring process according to the embodiment. Fig. 11(a) is a plan view of an object showing a cutting process according to a modified example, and Fig. 11(b) is a plan view of the object showing a continuation of Fig. 11(a). Fig. 12(a) is a plan view of an object showing a peeling process according to a modified example, and Fig. 12(b) is a plan view of the object showing a continuation of Fig. 12(a).

The following describes in detail an embodiment of the present invention with reference to the drawings. Note that the same or corresponding parts in each drawing are given the same reference numerals, and duplicated explanations will be omitted.

As shown in FIG. 1, the object processing system 101 is a system for processing an object 100, and includes a laser processing device 1, an object transport mechanism 40, and a grinding device 60.

[Laser processing equipment]
The laser processing device 1 is a device that forms a modified region in the object 100 by irradiating the object 100 with a laser beam by aligning a focusing position (at least a part of the focusing region, the focusing point) with the object 100. The laser processing device 1 irradiates the object 100 with a laser beam along a line along which the modified region is to be formed, before grinding by the grinding device 60, and forms one or more rows of modified regions along the line inside the object 100. The laser processing device 1 performs trimming and radial cutting on the object 100. The trimming is a process for removing unnecessary parts in the object 100. The radial cutting is a process for separating the unnecessary parts to be removed by the trimming. In this embodiment, the X direction and the Y direction are horizontal directions, and the Z direction is vertical directions.

As shown in FIG. 5, the object 100 has a first substrate 100T, a functional element layer 112, and a second substrate 100B. The first substrate 100T, the functional element layer 112, and the second substrate 100B are arranged so as to be stacked in this order. The first substrate 100T and the second substrate 100B are wafers formed in a disk shape. The first substrate 100T and the second substrate 100B are, for example, semiconductor substrates such as silicon substrates, piezoelectric material substrates formed from piezoelectric materials, and glass substrates formed from glass. The first substrate 100T and the second substrate 100B may be provided with a notch or orientation flat indicating the crystal orientation.

The functional element layer 112 includes a plurality of functional elements. Each functional element is, for example, a wiring element, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, etc. Each functional element may be configured three-dimensionally by stacking a plurality of layers, or may be arranged in a matrix. The functional element layer 112 here includes a plurality of metal layers and a plurality of non-metal layers. The metal layers include a Ti (titanium) layer and a Sn (tin) layer, etc. The non-metal layers include, for example, an oxide film layer and a nitride film layer. The non-metal layer 12b includes, for example, a SiO (silicon monoxide) layer and a SiCN (silicon carbon nitride) layer.

A line (annular line) M1 is set on the object 100 as a planned trimming line. The line M1 is a line that is planned to form a modified region by trimming. The line M1 extends in an annular shape inside the outer edge of the object 100. Here, the line M1 extends in an annular shape. The line M1 is set at the boundary between the removal region E to be removed by trimming and the effective region R inside it. The setting of the line M1 can be performed in a GUI (Graphical User Interface) 9 described later. The line M1 is a virtual line, but may be an actually drawn line. The line M1 may be specified by coordinates. The explanation regarding the setting of the line M1 is similar for the lines M2, M4, and M5 described later.

As shown in FIG. 6, a line (straight line) M2 is set on the target object 100 as a planned radial cut line. The line M2 is a line on which the formation of a modified region by radial cut processing is planned. When viewed from the laser light incident surface, the line M2 extends in a straight line (radially) along the radial direction of the target object 100. A plurality of lines M2 are set so that, when viewed from the laser light incident surface, the removal region E is equally divided (here, into four) in the circumferential direction.

As shown in FIG. 1, the laser processing device 1 includes a stage 7, a laser processing head 10A, a Z-axis rail 22, a Y-axis rail 24, an imaging unit 25, a GUI 9, and a control unit 8. The stage 7 is a support unit that supports an object 100. The stage 7 is configured to be rotatable about an axis parallel to the Z direction as a center line. The object 100 is placed on the stage 7. The stage 7 is rotated by the driving force of a known driving device such as a motor.

As shown in Figures 1 and 2, the laser processing head 10A irradiates the object 100 placed on the stage 7 with laser light L1 in the Z direction via the focusing unit 14, forming a modified region inside the object 100. The laser processing head 10A can be moved linearly in the Z direction along the Z-axis rail 22 by the driving force of a known driving device such as a motor. The laser processing head 10A can be moved linearly in the Y direction along the Y-axis rail 24 by the driving force of a known driving device such as a motor. The laser processing head 10A constitutes the irradiation unit. The focusing unit 14 includes a focusing lens.

As shown in FIG. 2, the laser processing head 10A includes a housing 11, an entrance section 12, an adjustment section 13, and a focusing section 14. The entrance section 12 causes the laser light L1 output from a light source (not shown) to enter the housing 11. The light source outputs the laser light L1 that is transparent to the target object 100, for example, by a pulse oscillation method. The adjustment section 13 is disposed in the housing 11. The adjustment section 13 adjusts the laser light L1 that is incident from the entrance section 12. Each component of the adjustment section 13 is attached to an optical base 29 provided in the housing 11. The optical base 29 is integrated with the housing 11.

The adjustment unit 13 has an attenuator 31, a beam expander 32, a mirror 33, a reflective spatial light modulator 34, and an imaging optical system 35. The attenuator 31 adjusts the output of the laser light L1 incident from the incident unit 12. The beam expander 32 expands the diameter of the laser light L1 whose output has been adjusted by the attenuator 31. The mirror 33 reflects the laser light L1 whose diameter has been expanded by the beam expander 32. The reflective spatial light modulator 34 modulates the laser light L1 reflected by the mirror 33. The reflective spatial light modulator 34 is, for example, a reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator). The imaging optical system 35 constitutes a double-telecentric optical system in which the reflecting surface 34a of the reflective spatial light modulator 34 and the entrance pupil surface 14a of the light collecting unit 14 are in an imaging relationship. The imaging optical system 35 is composed of three or more lenses.

The focusing unit 14 is arranged to be inserted into a hole 26a formed in the bottom wall of the housing 11. The focusing unit 14 focuses the laser light L1 adjusted by the adjustment unit 13 and emits it outside the housing 11.

In the laser processing head 10A, the laser light L1 enters the housing 11 from the entrance section 12 and travels therethrough, is reflected in sequence by the mirror 33 and the reflective spatial light modulator 34, and is then emitted from the focusing section 14 to the outside of the housing 11. The arrangement order of the attenuator 31 and the beam expander 32 may be reversed. The attenuator 31 may also be disposed between the mirror 33 and the reflective spatial light modulator 34. The adjustment section 13 may also have other optical components (for example, a steering mirror disposed in front of the beam expander 32).

The laser processing head 10A further includes a dichroic mirror 15, a distance measurement sensor 16, an observation unit 17, an actuator 18, and a circuit unit 19. The dichroic mirror 15 is disposed between the imaging optical system 35 and the light collecting unit 14. The dichroic mirror 15 transmits the laser light L1. 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.

The distance measurement sensor 16 is a sensor that irradiates the laser light L10 for distance measurement onto the laser light incident surface of the object 100 and receives the reflected light of the laser light L10 for distance measurement reflected by the laser light incident surface. The distance measurement sensor 16 acquires information on the received reflected light as measurement data on the displacement (including unevenness and inclination, etc.) of the laser light incident surface of the object 100. The measurement data is displacement data. The measurement data is, for example, a voltage value according to the received reflected light. Since the distance measurement sensor 16 is a sensor coaxial with the laser light L1, a sensor using an astigmatism method or the like can be used. In addition, if the sensor is on a different axis from the laser light L1, a sensor using a triangulation method, a laser confocal method, a white light confocal method, a spectral interference method, an astigmatism method, or the like can be used as the distance measurement sensor 16. The type of the distance measurement sensor 16 is not particularly limited, and various sensors can be used. In addition, a triangulation type sensor that uses the eccentricity of the distance measurement laser light L10 in the light collecting unit 14 and its reflected light can be used as the distance measurement sensor 16 that is coaxial with the laser light L1. The distance measurement sensor 16 constitutes the measurement data acquisition unit.

The observation unit 17 outputs observation light L20 for observing the laser light incident surface of the object 100, and detects the observation light L20 reflected at the laser light incident surface. In other words, the observation light L20 output from the observation unit 17 is irradiated onto the laser light incident surface via the focusing unit 14, and the observation light L20 reflected at the laser light incident surface is detected by the observation unit 17 via the focusing unit 14. The wavelengths of the laser light L1, the distance measurement laser light L10, and the observation light L20 are different from each other (at least the central wavelengths of the respective light beams are shifted from each other).

The actuator 18 is attached to the optical base 29. The actuator 18 moves the focusing unit 14 along the Z direction, which is the optical axis direction of the laser light L1, for example, by the driving force of a piezoelectric element. The circuit unit 19 is, for example, a plurality of circuit boards. The circuit unit 19 processes the signal output from the distance measurement sensor 16 and the signal input to the reflective spatial light modulator 34. The circuit unit 19 controls the actuator 18 based on the signal output from the distance measurement sensor 16. The circuit unit 19 is electrically connected to the control unit 8 (see FIG. 1).

The circuit unit 19 drives the actuator 18 so that the focusing unit 14 follows the laser light incident surface based on the measurement data acquired by the distance measurement sensor 16. For example, while acquiring a voltage value as measurement data by the distance measurement sensor 16, the actuator 18 is driven so that the voltage value becomes a target voltage value, and feedback control is performed to move the focusing unit 14 in the Z direction. This causes the focusing position to follow the displacement of the laser light incident surface. The target voltage value is a voltage value that serves as a reference (target) for driving the focusing unit 14 to follow the laser light incident surface, and is a value based on the voltage value acquired by the distance measurement sensor 16 when setting the height, which will be described later. Hereinafter, the control for driving the focusing unit 14 to follow the laser light incident surface is also referred to as AF (autofocus) tracking control. In AF tracking control, the focusing unit 14 moves along the Z direction based on the displacement data so that the distance between the laser light incident surface of the target object 100 and the focusing position of the laser light L1 is maintained constant.

The circuit unit 19 stores (acquires) the drive voltage value (control command value) that drives the actuator 18 so that the focusing unit 14 follows the laser light incident surface. Note that the function of driving the actuator 18 to follow and the function of storing the drive voltage value may be possessed by the control unit 8 or another circuit unit.

Returning to FIG. 1, the Z-axis rail 22 is a rail that extends along the Z direction. The Z-axis rail 22 is attached to the laser processing head 10A via the mounting portion 21. The Z-axis rail 22 moves the laser processing head 10A along the Z direction so that the focusing position of the laser light L1 moves along the Z direction. The Y-axis rail 24 is a rail that extends along the Y direction. The Y-axis rail 24 is attached to the Z-axis rail 22 via the mounting portion 23. The Y-axis rail 24 moves the laser processing head 10A along the Y direction so that the focusing position of the laser light L1 moves along the Y direction. The Z-axis rail 22 and the Y-axis rail 24 constitute a moving mechanism. Hereinafter, the focusing position of the laser light L1 by the focusing portion 14 is also simply referred to as the "focusing position".

The imaging unit 25 images the object 100 from a direction along the incident direction of the laser light L1. The imaging unit 25 includes an alignment camera AC and an imaging unit IR. The alignment camera AC and the imaging unit IR are attached to the mounting portion 21 together with the laser processing head 10A. The alignment camera AC images, for example, a device pattern, etc., using light that passes through the object 100. The image obtained in this way is used to align the irradiation position of the laser light L1 with respect to the object 100.

The imaging unit IR captures an image of the object 100 using light that passes through the object 100. For example, when the object 100 is a wafer containing silicon, light in the near-infrared region is used in the imaging unit IR. The imaging unit IR has a light source, an objective lens, and a light detection unit. The light source outputs light that is transparent to the object 100. The light source is composed of, for example, a halogen lamp and a filter, and outputs, for example, light in the near-infrared region. The light output from the light source is guided by an optical system such as a mirror, passes through the objective lens, and is irradiated onto the object 100. The objective lens passes light reflected by the surface opposite to the laser light incident surface of the object 100. In other words, the objective lens passes light that has propagated (passed) through the object 100. The objective lens has a correction ring. The correction ring corrects aberrations that occur in the light within the object 100 by, for example, adjusting the distance between the multiple lenses that make up the objective lens. The light detection unit detects light that has passed through the objective lens. The light detection unit is, for example, composed of an InGaAs camera, and detects light in the near-infrared region. The imaging unit IR can capture images of at least one of the modified region formed inside the target object 100 and the crack extending from the modified region. In the laser processing device 1, the processing state of the laser processing can be confirmed non-destructively using the imaging unit IR.

The control unit 8 is configured as a computer device including a processor, memory, storage, and communication devices. In the control unit 8, software (programs) loaded into the memory, etc. are executed by the processor, and the reading and writing of data in the memory and storage, as well as communication by the communication devices, are controlled by the processor. The control unit 8 controls each part of the laser processing device 1 and realizes various functions.

The control unit 8 controls at least the stage 7, the laser processing head 10A, the movement of the laser processing head 10A along the Z-axis rail 22, and the movement of the laser processing head 10A along the Y-axis rail 24. The control unit 8 controls the rotation of the stage 7, the irradiation of the laser light L1 from the laser processing head 10A, and the movement of the focusing position of the laser light L1. The control unit 8 can execute various controls based on rotation information (hereinafter also referred to as "θ information") regarding the amount of rotation of the stage 7. The θ information may be obtained from the drive amount of a drive device that rotates the stage 7, or may be obtained by a separate sensor or the like. The θ information can be obtained by various known methods.

The control unit 8 rotates the stage 7 while positioning the focusing position on the line M1 on the target object 100, and performs a trimming process to form a modified region along the line M1 by controlling the start and stop of irradiation of the laser light L1 in the laser processing head 10A based on the θ information under AF tracking control. The trimming process is a process of the control unit 8 that realizes the trimming process.

Without rotating the stage 7, the control unit 8 positions the focusing position on the line M2 on the target 100, and under AF tracking control, controls the start and stop of irradiation of the laser light L1 in the laser processing head 10A, and executes a radiation cut process to form a modified region along the line M2 by moving the focusing position of the laser light L1 along the line M2. The radiation cut process is a process of the control unit 8 that realizes the radiation cut processing.

The formation of the modified region and its stop can be switched as follows. For example, in the laser processing head 10A, the start and stop (ON/OFF) of the irradiation (output) of the laser light L1 can be switched to form the modified region and stop the formation. Specifically, when the laser oscillator is composed of a solid-state laser, the start and stop of the irradiation of the laser light L1 can be switched at high speed by switching ON/OFF of a Q switch (AOM (acousto-optical modulator), EOM (electro-optical modulator), etc.) provided in the resonator. When the laser oscillator is composed of a fiber laser, the start and stop of the irradiation of the laser light L1 can be switched at high speed by switching ON/OFF of the output of the semiconductor laser constituting the seed laser and the amplifier (excitation) laser. When the laser oscillator uses an external modulation element, the irradiation of the laser light L1 is switched on and off at high speed by switching on and off the external modulation element (AOM, EOM, etc.) installed outside the resonator.

Alternatively, the formation of the modified region and its stop may be switched as follows. For example, the optical path of the laser light L1 may be opened and closed by controlling a mechanical mechanism such as a shutter, and the formation of the modified region and its stop may be switched. The formation of the modified region may be stopped by switching the laser light L1 to CW light (continuous wave). The formation of the modified region may be stopped by displaying a pattern (for example, a pear-skin pattern that scatters the laser) that makes the focused state of the laser light L1 in a state where it cannot be modified on the liquid crystal layer of the reflective spatial light modulator 34. The formation of the modified region may be stopped by controlling an output adjustment unit such as an attenuator to reduce the output of the laser light L1 so that the modified region cannot be formed. The formation of the modified region may be stopped by switching the polarization direction. The formation of the modified region may be stopped by scattering (scattering) the laser light L1 in a direction other than the optical axis and cutting it.

The GUI 9 displays various types of information. The GUI 9 includes, for example, a touch panel display. Various settings related to processing conditions are input to the GUI 9 by a user's operation such as touching. The GUI 9 constitutes an input unit that accepts input from the user.

The example shown in FIG. 3(a) is a diagram showing an example of an input/output screen of GUI 9. FIG. 3(a) shows an example of a case where four rows of modified regions are formed inside the target object 100. In FIG. 3(a), SD1, SD2, SD3, and SD4 indicate modified regions in this order, which are farther from the laser light incident surface (closer to the planned grinding position). The Z-height corresponds to the planned position of the modified region. The Z-height is defined so that the laser light incident surface is set as the reference (0) and the value increases as it goes from the laser light incident surface to the inside of the target object 100. The planned position of the modified region is expressed, for example, by Z-height x DZ rate ±α. The DZ rate is a predetermined value that is set in advance. α is a correction value according to the settings of various processing conditions and is a value determined by experience. The output corresponds to the output of the laser light L1 when forming the modified region.

In GUI 9, the user can input the Z-height, output, and detailed conditions for each of SD1 to SD4. In addition, in GUI 9, the user can input the error detection position T2 (see FIG. 4), which will be described later. The Z-height of SD1 corresponds to the planned formation position T1 (see FIG. 4) of the modified region 4T, which is closest to the planned grinding position. Each condition set in the laser processing device 1 is set based on the final thickness of the first substrate 100T.

[Object transport mechanism]
The object transport mechanism 40 is a mechanism that transports the object 100 after being processed by the laser processing device 1 to the grinding device 60. The object transport mechanism 40 includes an arm 41 capable of holding the object 100, a slider 42 provided on the base end side of the arm 41, and a rail 43 for moving the slider 42 in the horizontal direction. The configuration of the object transport mechanism 40 is not particularly limited, and various known configurations can be adopted as long as the object 100 can be transported between the laser processing device 1 and the grinding device 60.

The object transport mechanism 40 includes a control unit 48 and a GUI 49. The control unit 48 is configured as a computer device including a processor, memory, storage, and a communication device. In the control unit 48, software loaded into the memory, etc. is executed by the processor, and the reading and writing of data in the memory and storage, as well as communication by the communication device, are controlled by the processor. The control unit 48 controls each part of the object transport mechanism 40 to realize various functions. The GUI 49 displays various information. The GUI 49 includes, for example, a touch panel display. Various settings related to transport conditions are input into the GUI 49 by the user's operation such as touching.

[Grinding device]
The grinding device 60 is a device that grinds the object 100 after being processed by the laser processing device 1. The grinding device 60 is a device that grinds a portion of the object 100 from the surface 100a to a planned grinding position T3 (see FIG. 4). The grinding device 60 includes a grinding wheel 61 that is a grinding stone that can rotate at high speed, a base 62 that rotatably supports the grinding wheel, a vertical rail 63 for moving the base 62 in the vertical direction, a horizontal rail 64 for moving the base 62 in the horizontal direction, a thickness gauge 66 that measures the thickness of the object 100 to be ground, and a stage 67 on which the object 100 to be ground is placed. The stage 67 is configured to be rotatable about an axis parallel to the vertical direction as a center line.

The grinding device 60 includes a control unit 68 and a GUI 69. The control unit 68 is configured as a computer device including a processor, memory, storage, and a communication device. In the control unit 68, software loaded into the memory, etc. is executed by the processor, and the reading and writing of data in the memory and storage, as well as communication by the communication device, are controlled by the processor. The control unit 68 controls each part of the grinding device 60 and realizes various functions. The GUI 69 displays various information. The GUI 69 includes, for example, a touch panel display. Various settings related to grinding conditions are input into the GUI 69 by the user's touch or other operations.

3B shows an example of an input/output screen of the GUI 69. In the figure, the pre-processing thickness is the thickness H1 (see FIG. 4) of the object 100 before grinding by the grinding device 60. The finishing thickness is the thickness H2 (see FIG. 4) of the object 100 after grinding by the grinding device 60. The stage rotation speed is the rotation speed of the stage 67 during grinding by the grinding device 60. The grinding wheel rotation speed is the rotation speed of the grinding wheel 61 during grinding by the grinding device 60. In the GUI 69, the user can input the pre-processing thickness, finishing thickness, stage rotation speed, grinding wheel rotation speed, and detailed conditions. Each condition set by the grinding device 60 is set based on the final thickness of the first substrate 100T.

The main parts of this embodiment will be explained further below.

The circuit unit 19 and the control unit 8 of the laser processing device 1 execute a trimming process (light focusing process), a radiation cut process, and a monitoring process. In the trimming process, the laser processing head 10A focuses the laser light L1 inside the object 100, and while rotating the stage 7 so that the focusing position of the laser light L1 moves along the line M1, AF tracking control is performed to make the focusing position follow the displacement of the surface 100a, which is the laser light incident surface. In the radiation cut process, the laser processing head 10A focuses the laser light L1 inside the object 100, and while moving at least one of the stage 7 and the laser processing head 10A so that the focusing position of the laser light L1 moves along the line M2, AF tracking control is performed to make the focusing position follow the displacement of the surface 100a, which is the laser light incident surface.

When the laser light L1 is focused inside the target object 100, the laser light L1 is particularly absorbed in the portion corresponding to the focused position of the laser light L1, and a modified region is formed inside the target object 100. The modified region is a region whose density, refractive index, mechanical strength, and other physical properties are different from the surrounding unmodified region. Examples of modified regions include melting treatment regions, crack regions, insulation breakdown regions, and refractive index change regions.

When the laser light L1 output by the pulse oscillation method is irradiated onto the object 100 and the focal position of the laser light L1 is moved relatively along the lines M1, M2 set on the object 100, multiple modified spots are formed so as to be lined up in a row along the lines M1, M2. One modified spot is formed by irradiation with one pulse of the laser light L1. 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 focal position of the laser light L1 with respect to the object 100 and the repetition frequency of the laser light. The shape of the set lines M1, M2 may be a lattice shape, a ring shape, a straight line shape, a curved shape, or a shape that combines at least any of these.

The monitoring process monitors whether the modified region 4 formed by focusing the laser light L1 on the focusing position in the AF tracking control of the trimming process exceeds the error detection position T2 (see FIG. 4) toward the planned grinding position T3 in the Z direction. As shown in FIG. 4, the error detection position T2 is a position determined between the planned formation position T1 of the modified region 4T closest to the planned grinding position and the planned grinding position T3. The planned formation position T1 is a position where the modified region 4T is planned to be formed. The planned formation position T1 can be based on the end of the modified region 4T on the planned grinding position T3 side. The error detection position T2 corresponds to the value of the error detection position input by the user via the GUI 9. The error detection position T2 may be set to an intermediate position between the planned formation position T1 and the planned grinding position T3. The error detection position T2 may be a value that is automatically determined according to the planned grinding position T3.

In the monitoring process, the meandering amount of the AF tracking control is calculated, and whether or not the calculated meandering amount exceeds the distance in the Z direction from the planned formation position T1 to the error detection position T2 (hereinafter, also referred to as the "allowable meandering range") is monitored. In this way, whether or not the modified region 4T passes the error detection position T2 toward the planned grinding position T3 side in the AF tracking control is monitored. In the monitoring process, when it is determined that the modified region 4T passes the error detection position T2 toward the planned grinding position T3 side, an error display is displayed on the GUI 9. In this case, the GUI 9 constitutes a display unit. In the monitoring process, information indicating that the modified region 4T passes the error detection position T2 toward the planned grinding position T3 side may be output to the outside of the laser processing device 1. The meandering amount corresponds to the amount of deviation in the Z direction when the position of the modified region 4 formed by the focusing of the laser light L1 under the AF tracking control deviates from the planned formation position of the modified region 4. The meandering amount can be expressed, for example, by the following formula.
Wobble amount=AF difference signal×rate The AF difference signal is the difference between the target voltage value and the post-feedback voltage value, which is the voltage value acquired by the distance measurement sensor 16 as a result of the AF tracking control. The rate is a preset parameter. The post-feedback voltage value is the target voltage value when the AF tracking control is realized to track the focusing position with high accuracy (in this case, the AF difference signal=0). On the other hand, when the AF tracking control is not realized to track the focusing position with high accuracy due to some circumstances, the post-feedback voltage value becomes a value that is deviated from the target voltage value (in this case, the AF difference signal≠0).

That is, in the monitoring process, feedback control is performed to move the focusing unit 14 in the Z direction by the actuator 18 so that the measurement data becomes the target voltage value, thereby making the focusing position follow the displacement of the laser light incidence surface. In the monitoring process, based on the difference (AF difference signal) between the post-feedback voltage value acquired by the distance measurement sensor 16 as a result of the feedback control and the target voltage value, it is monitored whether the modified region 4T passes the error detection position T2 toward the planned grinding position T3.

In the trimming process, if the focusing position in the direction along the line M1 is in the error region (see FIG. 10) when the monitoring process determines that the modified region 4T has exceeded the error detection position T2 toward the intended grinding position T3, the drive voltage value of the actuator 18 is fixed (so that it does not fluctuate from the voltage value immediately before that) and the position of the focusing section 14 in the Z direction is fixed.

Next, an example of an object processing method for processing an object 100 using the object processing system 101 will be described.

First, the laser processing process is performed in the laser processing device 1. That is, as shown in FIG. 5(a) and FIG. 5(b), the object 100 is placed on the stage 7 with the surface 100a facing the laser incident surface. Next, the trimming process is performed. In the trimming process, the control unit 8 executes the trimming process based on the processing conditions input via the GUI 9. In the trimming process, while rotating the stage 7 at a constant rotation speed, the start and stop of the irradiation of the laser light L1 in the laser processing head 10A is controlled based on the θ information under the AF tracking control with the focusing position positioned on the line M1. As a result, as shown in FIG. 6(a) and FIG. 6(b), the modified region 4 is formed along the line M1 inside the first substrate 100T of the object 100. Here, four rows of modified regions 4 are formed in the Z direction inside the object 100. The formed modified region 4 includes a modified spot and a crack C extending from the modified spot.

Next, the radiation cut processing is performed. In the radiation cut processing, the control unit 8 executes the radiation cut processing based on the processing conditions inputted via the GUI 9. In the radiation cut processing, the laser processing head 10A irradiates the laser light L1 without rotating the stage 7, and the laser processing head 10A is moved along the Y-axis rail 24 under AF tracking control so that the focusing position moves along the line M2. After rotating the stage 7 by 90 degrees, the laser processing head 10A irradiates the laser light L1 without rotating the stage 7, and the laser processing head 10A is moved along the Y-axis rail 24 under AF tracking control so that the focusing position moves along the line M2. This forms one or more rows of modified regions 4 along the line M2. The formed modified regions 4 include modified spots and cracks extending from the modified spots. Then, as shown in Figures 7(a) and 7(b), the removal area E is cut and removed (removed) using, for example, a jig or air, with the modified area 4 as the boundary.

Then, based on the transport conditions, etc. input via the GUI 49, the object 100 is transported from the laser processing device 1 to the grinding device 60 by the object transport mechanism 40. Next, based on the grinding conditions, etc. input via the GUI 69, the grinding process is performed by the grinding device 60. That is, as shown in FIG. 8, the portion from the surface 100a of the object 100 to the intended grinding position T3 (see FIG. 4) is ground by the polishing wheel 61 based on the measurement results of the object thickness gauge 66. As a result of the above, the semiconductor device 100K is obtained (manufactured).

Next, trimming processing will be explained in detail with reference to the flowchart in Figure 9.

First, information regarding the planned formation positions of each of the multiple modified regions 4 to be formed is input and set in the GUI 9 of the laser processing device 1. Information regarding the planned formation position of the modified region 4T closest to the planned grinding position T3 (see FIG. 4) is set so that the modified region 4T is located closer to the surface 100a than the planned grinding position T3 (step S1). At this time, the extension amount of the crack C and the above-mentioned allowable meandering range are taken into consideration. At the same time, an error detection position is input and set in the GUI 9 of the laser processing device 1 (step S2: input process).

Note that, here, each setting in GUI 9 is input by the user based on the settings of GUI 69 of grinding device 60, but when information regarding the settings of GUI 69 of grinding device 60 is input by communication or the like, the settings may be automatically set from that information. Also, when information regarding the settings of GUI 69 of grinding device 60 is input by communication or the like, each setting in GUI 9 may be input by the user under guidance and restrictions based on that information.

As an example, the planned formation position of the modified region 4T closest to the planned grinding position T3 (see FIG. 4) is set so that the bottom end distance of the modified region 4T (the distance to the main surface of the first substrate 100T on the second substrate 100B side) exceeds 50 μm, which is the finished thickness of the first substrate 100T. Taking into account the allowable meandering range of the AF tracking control and the extension amount of the crack C, the planned formation position of the modified region 4T is set so that the bottom end distance of the modified region 4T is 65 μm. In this case, the allowable amount of meandering is 15 μm, which is the planned formation position of the modified region 4T (bottom end distance 65 μm) minus the finished thickness of the first substrate 100T, 50 μm. An error detection position is set between these positions. For example, the error detection position is set to a position where a meandering amount of 12 μm or more occurs.

Next, for example, based on an image of the laser light incident surface of the object 100 acquired by the imaging unit 25, the control unit 8 moves the laser processing head 10A along the Z direction so that the focusing position is located on the laser light incident surface, and moves the focusing unit 14 along the Z direction. Such alignment of the focusing unit 14 with respect to the laser light incident surface is called "height set", and the position of the focusing unit 14 at this time is called the height set position. In height setting, the focusing position may be aligned on the line M1 on the laser light incident surface of the object 100, or the focusing position may be aligned to the center of the laser light incident surface of the object 100.

Next, AF tracking control is performed before trimming processing, and measurement data and an AF difference signal are acquired (step S3: data acquisition process and monitoring process). In the above step S3, the laser processing head 10A does not irradiate the laser light L1, and while rotating the stage 7, the distance measurement sensor 16 acquires a voltage value as measurement data. In addition, in the above step S3, the actuator 18 is driven by the circuit unit 19 so that the voltage value as measurement data acquired by the distance measurement sensor 16 becomes the target voltage value, and AF tracking control is performed, which is feedback control that moves the focusing unit 14 in the Z direction to follow the displacement of the laser light incident surface. Also, in the above step S3, the circuit unit 19 acquires a post-feedback voltage value, which is a voltage value acquired by the distance measurement sensor 16 as a result of the AF tracking control, in association with the position information (here, the θ position) of the target object 100. Then, in the above step S3, an AF difference signal, which is the difference between the target voltage value and the acquired post-feedback voltage value, is calculated. The AF difference signal is stored in the control unit 8 or the circuit unit 19.

In the AF tracking control, it is monitored whether or not the modified region 4T will meander beyond the error detection position T2 (step S4: monitoring process). In the above step S4, the amount of meandering when performing the AF tracking control is calculated based on the difference signal. In the above step S4, it is monitored whether or not the calculated amount of meandering exceeds the meandering tolerance range, which is the distance in the Z direction from the intended formation position T1 to the error detection position T2.

If it is determined as a result of the monitoring in step S4 that meandering beyond the error detection position T2 will occur, an error message is displayed on the GUI 9 (YES in step S5, step S6). The error message is not particularly limited, and may be a message that alerts the user to the occurrence of meandering beyond the error detection position T2. In addition to the error message, a sound may be output from the GUI 9.

After step S6, trimming including AF tracking control is performed to fix the drive voltage value of the actuator 18 when the focusing position is located in the error region (see FIG. 10) that is the range of θ positions where meandering beyond the error detection position T2 occurs (step S7: focusing process). That is, in step S7, trimming including AF tracking control (with fixing of the drive voltage value of the actuator 18) is performed. In the AF tracking control in step S7, specifically, the actuator 18 is driven by the circuit unit 19 so that the voltage value as the measurement data becomes the target voltage value, and the focusing unit 14 is moved in the Z direction to follow the displacement of the laser light incidence surface, and when the focusing position in the direction along the line M1 is in the error region, the drive voltage value of the actuator 18 is fixed to the drive voltage value at the θ position immediately before the error region. In step S7, when the θ position of the focusing position is in the error region, the position of the focusing unit 14 in the Z direction is fixed.

On the other hand, if it is determined as a result of the monitoring in step S4 that no meandering beyond the error detection position T2 has occurred, trimming processing including normal AF tracking control (without fixing the drive voltage value of the actuator 18) is performed (NO in step S5, step S8: focusing process).

Figure 10 is a graph showing an example of the monitoring results of the monitoring process. Figure 10 shows the amount of meandering associated with the θ position of the focusing position, the planned formation position T1 of the modified region 4T, the error detection position T2, and the planned grinding position T3. In Figure 10, the θ position of the focusing position is shown on the horizontal axis, and each data is shown on the vertical axis. For ease of explanation, in Figure 10, the planned formation position T1, error detection position T2, and planned grinding position T3 are constant regardless of the θ position of the focusing position.

In the example shown in FIG. 10, when the θ position of the focusing position is between θ1 and θ2, the amount of meandering increases to the point where it exceeds the error detection position T2 downward (towards the planned grinding position T3). Such a region where the θ position of the focusing position is between θ1 and θ2 is the error region, and is the region of the focusing position in the direction along the line M1 when the modified region 4T is deemed to exceed the error detection position T2 towards the planned grinding position T3 in step S4 above. In this embodiment, in the error region, the drive voltage value of the actuator 18 is fixed and constant, the position of the focusing section 14 in the Z direction is fixed and constant, the focusing position does not follow the surface 100a, and the amount of meandering is constant.

As described above, in the object processing method and object processing system 101, when performing AF tracking control to make the focusing position follow the displacement of the laser light incident surface, it is monitored whether the modified region 4T formed by focusing at the focusing position exceeds the error detection position T2 before the planned grinding position T3 (on the surface 100a side). Therefore, if it is determined as a result of monitoring that the modified region 4T exceeds the error detection position T2, it is possible to take measures to prevent the modified region 4T from exceeding the planned grinding position T3, for example, by preventing the focusing position from approaching the planned grinding position T3 during that time. In other words, it is possible to prevent the modified region 4T from remaining in the object 100 after grinding.

In AF tracking control, an overshoot (a steep fluctuation) may occur in the voltage value of the distance measurement sensor 16 and/or the drive voltage value of the actuator 18 due to various locally occurring factors (e.g., vibration of the stage 7, unevenness of the laser light incident surface, changes in the reflectivity of the film on the laser light incident surface, roughness of the laser light incident surface, etc.). In this regard, in this embodiment, unnecessary overshoot can be predicted and avoided. It is possible to suppress damage such as cracks in the second substrate 100B when removing the removal area E before the grinding process. It is possible to suppress deterioration in the quality of the target object 100 after trimming processing.

In the object processing method, the measurement data is a voltage value corresponding to the reflected light acquired by the distance measurement sensor 16. In this case, the distance measurement sensor 16 can be used to monitor whether the modified region 4T passes the error detection position T2 toward the intended grinding position T3.

In the object processing method, the monitoring step includes a step of performing AF tracking control to cause the focusing position to follow the displacement of the laser light incident surface, and a step of monitoring whether the modified region 4T crosses the error detection position T2 toward the intended grinding position T3 based on the difference (AF difference signal) between the post-feedback voltage value acquired by the distance measurement sensor 16 as a result of the AF tracking control and the target voltage value. In this case, by effectively utilizing the distance measurement sensor 16, it is possible to monitor whether the modified region 4T crosses the error detection position T2 toward the intended grinding position T3.

In the method for machining an object, the monitoring process calculates the amount of meandering in the AF tracking control and monitors whether the amount of meandering exceeds the distance in the Z direction from the intended formation position T1 to the error detection position T2. In this case, the amount of meandering can be used to monitor whether the modified region 4T exceeds the error detection position T2 toward the intended grinding position T3.

In the monitoring process, the amount of meandering in the AF tracking control may not be calculated, and the measurement data may be used directly to monitor so that the modified region 4T does not remain in the target object 100 after grinding. Specifically, in the AF tracking control, it may be monitored whether the AF difference signal exceeds a voltage value corresponding to the distance from the intended formation position T1 to the error detection position T2. In this case, it is possible to efficiently use the distance sensor 16 to monitor whether the modified region 4T passes the error detection position T2 toward the intended grinding position T3.

In the object processing method, the laser processing step includes an input step of inputting the error detection position T2 via the GUI 9. In this case, the user can set the desired error detection position T2 via the GUI 9.

In the object processing method, in the focusing process, if the focusing position in the direction along the line M1 is in the error region, the focusing position in the Z direction is fixed. In this case, specific measures can be taken to ensure that the modified region 4 does not exceed the intended grinding position T3.

In the object processing method, in the monitoring process, if it is determined that the modified region 4T exceeds the error detection position T2 toward the intended grinding position T3, an error message is displayed on the GUI 9. In this case, the error message displayed on the GUI 9 can inform the user that, for example, the modified region 4T remains in the object 100 after grinding, or there is a high possibility that this will occur.

The present invention is not limited to the above-described embodiment.

In the above-described embodiment and modified example, when the focusing position in the direction along the line M1 is in an error region in the trimming process, the driving voltage value of the actuator 18 in the AF tracking control is fixed to fix the focusing unit (focusing lens) 14 in the Z direction, but this is not limited to this. For example, when the focusing position in the direction along the line M1 is in an error region in the trimming process, the voltage value as the measurement data may be fixed. Also, for example, when the focusing position in the direction along the line M1 is in an error region in the trimming process, the irradiation of the laser light L1 to the target object 100 may be stopped. In this case, specific measures can be taken so that the modified region 4T does not exceed the planned grinding position T3.

Alternatively, for example, in the trimming process, if the focusing position in the direction along the line M1 is in an error region, the control parameters related to the tracking of the focusing position in the AF tracking control may be changed so that the tracking becomes slower. Specifically, the change in the control parameters here may be at least one of reducing the gain of the control parameters of the PID control implemented in the AF tracking control, increasing the proportional band, and increasing the integral time so that an overshoot (sharp fluctuation) does not occur in the drive voltage value of the actuator 18. In this case, specific measures can also be taken so that the modified region 4T does not exceed the planned grinding position T3.

In addition, since AF tracking control may only require tracking of gradual displacements (e.g., about 2 μm/10 mm) of the laser light incident surface, there is no problem with quality even if the actuator 18 is fixed without tracking sudden displacements (e.g., 2 μm/0.1 mm) of the laser light incident surface caused by foreign matter, or the actuator 18 is driven slowly so that tracking becomes slow.

Alternatively, for example, in the trimming process, if the focusing position in the direction along the line M1 is in an error region, control may be further performed to forcibly move the focusing unit 14 a predetermined distance in a direction approaching the surface 100a. In this case, specific measures can also be taken to prevent the modified region 4T from exceeding the planned grinding position T3.

In the above-described embodiment and modified example, in the AF tracking control in the trimming process, it is monitored whether the modified region 4T passes over the error detection position T2, but this is not limiting. For example, in the AF tracking control in the radial cut process, it may be monitored whether the modified region passes over the error detection position. In the above-described embodiment and modified example, various measures are taken to prevent the modified region 4T from passing over the error detection position T2 in the trimming process, but this is not limiting. For example, in the radial cut process, various measures may be taken to prevent the modified region 4T from passing over the error detection position T2.

In the above-described embodiment and modified example, the radial cut process is performed after the trimming process, but the present invention is not limited to this. For example, in the above-described embodiment and modified example, a cutting process (cutting process) may be performed after the trimming process and before the grinding process to form a modified region inside the effective region R along lines extending in a lattice pattern. Specifically, as shown in FIG. 11(a) and FIG. 11(b), after the trimming process, a modified region 4 may be formed in the effective region R along a straight line M4. A plurality of lines M4 are set on the target object 100. The plurality of lines M4 are set in a lattice pattern at least in the effective region R. In this case, in the AF tracking control in the cutting process, it may be monitored whether the modified region exceeds the error detection position. In the cutting process, various measures may be taken to prevent the modified region from exceeding the error detection position.

Alternatively, for example, a peeling process (peeling process) may be performed after the trimming process and before the grinding process. Specifically, as shown in Figs. 12(a) and 12(b), after the trimming process, a modified region 4 may be formed along a line M5 on a virtual surface inside the target object 100. The line M5 is set in the effective region R. The line M5 extends in a spiral shape centered on the central position of the target object 100. In this case, in the AF tracking control in the peeling process, it may be monitored whether the modified region passes the error detection position. In the peeling process, various measures may be taken to prevent the modified region from passing the error detection position.

In the above embodiment and modified example, the voltage value corresponding to the reflected light received by the distance sensor 16 is used as the measurement data, but the measurement data is not particularly limited as long as it is data related to the displacement of the laser light incidence surface, and such measurement data can be acquired by various known techniques. The measurement data may be a voltage value acquired by a distance sensor provided on a different axis from the optical axis of the laser light L1. In this case, the acquired voltage value can be treated in the same way as the voltage value of the distance sensor 16 described above. The measurement data may be data related to the position of the movable part of the actuator 18. When a separate sensor capable of measuring the surface shape of the laser light incidence surface of the target object 100 is used, data related to the detection result of the sensor may be used as the measurement data. The measurement data may be the absolute position of the focusing unit 14 in the Z direction. The measurement data may be the relative position of the focusing unit 14 in the Z direction with respect to the position when the height is set.

In the above-described embodiment and modified example, the amount of meandering may be calculated only from the measurement data without acquiring the AF difference signal. Specifically, it may be possible to monitor whether or not a displacement that exceeds the driving capacity of the actuator 18 occurs from the displacement of the laser light incidence surface per moving distance (moving time) of the focusing position, and calculate the excess displacement as the amount of meandering. As an example, when processing with the moving distance of the focusing position set to 300 mm/s, if an actuator 18 having a driving capacity capable of following a displacement of 2 μm at a moving distance of 10 mm is installed, if the displacement of the laser light incidence surface at a moving distance of 10 mm is 4 μm, it may be possible that at least a meandering of about 2 μm (2 μm × rate (here 4) = about 8 μm in the target 100) may occur. In this case, since it is possible that an overshoot actually occurs, it may be possible to monitor whether or not the modified region 4T exceeds the error detection position T2, further considering the possibility of the occurrence of an overshoot.

In the above-described embodiment and modified example, the drive voltage value of the actuator 18 (position of the movable part of the actuator 18) and the displacement of the laser light incident surface may be used to monitor whether the modified region 4T passes over the error detection position T2. For example, in this case, the drive voltage value of the actuator 18 may be converted into the amount of movement of the focusing part 14 (focusing position) in the Z direction and compared with the displacement value of the laser light incident surface, and whether the modified region 4T passes over the error detection position T2 may be monitored based on the comparison result.

In the above-described embodiment and modified example, the difference between the drive voltage value of the actuator 18 and the current position of the movable part of the actuator 18 may be used to monitor whether the modified region 4T will pass the error detection position T2. In the above-described embodiment and modified example, the difference between the drive voltage value of the actuator 18 and the current position of the movable part of the actuator 18 may be used to monitor whether the modified region 4T will pass the error detection position T2.

In the above-described embodiment and modification, the surface 100a of the object 100 is the laser light incidence surface, but another surface of the object 100 may be the laser light incidence surface. In the above-described embodiment and modification, the modified region 4 may be, for example, a crystalline region, a recrystallized region, or a gettering region formed inside the object 100. The crystalline region is a region that maintains the structure of the object 100 before processing. The recrystallized region is a region that is solidified as a single crystal or polycrystal when resolidified after being evaporated, plasmatized, or melted. The gettering region is a region that exerts a gettering effect that collects and captures impurities such as heavy metals, and may be formed continuously or intermittently. In addition, for example, the laser processing device 1 may be applied to processing such as ablation.

In the above-described embodiment and modified examples, the movement mechanism may be configured to move at least one of the stage 7 and the laser processing head 10A. In the above-described embodiment and modified examples, the θ position is used as the position information, but instead of or in addition to this, at least one of the time from the start of laser processing and coordinate information may be used as the position information. The position information may be any information that indicates which position on the circumference of the target object 100 the data is for. In the above-described embodiment and modified examples, the height setting performed after trimming processing is omitted, but the height setting does not have to be omitted.

In the above-described embodiment and modified example, in step S3, AF tracking control is performed separately from the trimming process (light collection process) to obtain measurement data, but this is not limited to the above. For example, during trimming process (light collection process), so-called real-time processing may be performed in which AF tracking control is performed while irradiating laser light L1 to obtain measurement data.

In the above-described embodiment and modified example, in the monitoring process, in addition to monitoring whether the modified area 4T closest to the planned grinding position T3 exceeds the error detection position T2, it is also possible to monitor whether the modified areas 4 other than the modified area 4T exceed the error detection position T2. In this case, in the light collection process, the various measures described above may be taken depending on the monitoring results in the monitoring process so that the modified areas 4 other than the modified area 4T do not exceed the error detection position T2.

The components in the above-described embodiments and modifications are not limited to the materials and shapes described above, and various materials and shapes can be applied. Furthermore, the components in the above-described embodiments and modifications can be arbitrarily applied to the components in other embodiments or modifications.

1...laser processing device, 4...modified area, 4T...modified area (modified area closest to the planned grinding position), 7...stage (support), 8...control unit, 9...GUI (input unit, display unit), 10A...laser processing head (irradiation unit), 14...focusing unit (focusing lens), 16...distance measuring sensor (measurement data acquisition unit), 18...actuator, 19...circuit unit (measurement data acquisition unit, control unit), 22...Z-axis rail (movement mechanism), 24...Y-axis rail (movement mechanism), 60...grinding device, 100...object, 100a...surface (laser light incidence surface), 101...object processing system, L1...laser light, M1, M2, M4, M5...lines, T1...planned formation position, T2...error detection position, T3...planned grinding position.

Claims (10)

a grinding step of grinding a portion of the object from a surface to a planned grinding position;
a laser processing step of irradiating the object with laser light via a condenser lens along a line prior to the grinding step, and forming one or more rows of modified regions along the line within the object between the surface and the intended grinding position;
The laser processing step includes:
a data acquisition step of acquiring measurement data relating to a displacement of a laser light incident surface of the object;
a focusing step of moving a focusing position of the laser light along the line while causing the focusing position to follow a displacement of the laser light incident surface based on the measurement data;
a monitoring step of monitoring whether the modified region formed by focusing the laser light to the focusing position exceeds an error detection position defined in the optical axis direction of the focusing lens between the intended formation position of the modified region closest to the intended grinding position and the intended grinding position, when the focusing position is made to follow the displacement of the laser light incident surface based on the measurement data, toward the intended grinding position. In the monitoring step,
When the focusing position is caused to follow the displacement of the laser light incident surface based on the measurement data, a meandering amount corresponding to a deviation amount in the optical axis direction when a position of the modified region formed by focusing the laser light at the focusing position deviates from a planned position of the modified region is calculated;
The method for processing an object according to claim 1 , further comprising monitoring whether or not the amount of meandering exceeds a distance in the optical axis direction from the intended formation position to the error detection position. The object processing method according to claim 1 or 2, wherein the measurement data is a voltage value corresponding to the reflected light acquired by a sensor that receives the reflected light of the distance measuring laser light reflected by the laser light incident surface. The monitoring step includes:
performing a feedback control for moving the condensing lens in the optical axis direction so that the measurement data becomes a target voltage value, thereby causing the condensing position to follow the displacement of the laser light incident surface;
The method for processing an object as described in claim 3, further comprising a step of monitoring whether the modified region extends beyond the error detection position toward the intended grinding position based on a difference between a post-feedback voltage value, which is a voltage value acquired by the sensor as a result of the feedback control, and the target voltage value. The object processing method according to any one of claims 1 to 4, wherein the laser processing step includes an input step of inputting the error detection position via an input unit. In the light collecting step,
A method for processing an object described in any one of claims 1 to 5, wherein when the focusing position in the direction along the line is in an error area when the modified area exceeds the error detection position toward the planned grinding position in the monitoring process, the position of the focusing lens in the optical axis direction is fixed. In the light collecting step,
A method for processing an object described in any one of claims 1 to 5, wherein when the focusing position in the direction along the line is in an error area when the monitoring process determines that the modified area exceeds the error detection position toward the planned grinding position, a control parameter related to tracking of the focusing position is changed so that the tracking becomes slower. In the light collecting step,
A method for processing an object described in any one of claims 1 to 5, wherein when the focusing position in the direction along the line is in an error area when the modified area exceeds the error detection position toward the planned grinding position in the monitoring process, irradiation of the laser light to the object is stopped. The object processing method according to any one of claims 1 to 8, wherein in the monitoring step, if it is determined that the modified region exceeds the error detection position toward the intended grinding position, an error message is displayed on a display unit. a grinding device for grinding a portion of an object from a surface to a predetermined grinding position;
a laser processing device that irradiates the object with laser light via a condenser lens along a line before grinding by the grinding device, and forms one or more rows of modified regions along the line between the surface and the intended grinding position inside the object,
The laser processing apparatus includes:
A support portion that supports the object;
an irradiation unit that irradiates the object with the laser light via the condenser lens;
a moving mechanism that moves at least one of the support unit and the irradiation unit so as to move a focusing position of the laser light;
an actuator that drives the condenser lens along an optical axis direction of the condenser lens;
a measurement data acquisition unit that acquires measurement data relating to a displacement of a laser light incident surface of the object onto which the laser light is incident;
a control unit that controls the irradiation unit, the movement mechanism, and the actuator,
The control unit is
a focusing process in which at least one of the support unit and the irradiator is moved along the line so that a focusing position of the laser light moves along the line, while at least one of the support unit and the condensing lens is moved along the optical axis direction so that the focusing position follows a displacement of the laser light incident surface based on the measurement data;
a monitoring process for monitoring whether the modified region formed by focusing the laser light to the focusing position exceeds an error detection position defined in the optical axis direction between the planned formation position of the modified region closest to the planned grinding position and the planned grinding position, when at least one of the support part and the focusing lens is moved along the optical axis direction so that the focusing position follows the displacement of the laser light incident surface based on the measurement data, toward the planned grinding position.

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