JP2022036013A - Laser processing device and laser processing method - Google Patents

Abstract

To improve a processing quality by reducing variation in output of branched light.SOLUTION: A laser processing device 1 comprises a beam source unit 8, a reflection-type spatial beam modulator 34, a beam condensing part 14, a detecting part 17 and a control part 9. The control part 9 executes: first processing for making the reflection-type spatial beam modulator 34 display a first branching pattern in which a laser beam is branched into a plurality of beams; second processing for controlling the beam source unit 8 so that the laser beam is emitted with the reflection-type spatial beam modulator 34 displaying the first branching pattern; third processing for controlling the detecting part 17 so that a reflected beam of each laser beam branched by the first branching pattern is detected; fourth processing for deriving brightness of the reflected beam of each branched beam, on the basis of a detected result by the detecting part 17; and fifth processing for generating a second branching pattern in which the first branching pattern is corrected so that an output of each branched laser beam is uniformed, on the basis of the derived brightness.SELECTED DRAWING: Figure 5

Description

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

Patent Document 1 describes a laser processing apparatus including a laser light source, a spatial light modulator, and a light collection correction means different from the spatial light modulator. Such a laser processing apparatus divides and peels off an object by forming a modified region inside the object (wafer) by irradiating the object with laser light. In the technique described in Patent Document 1, a modified region is formed inside the object by irradiation with laser light, a part of the reflected light from the focusing point is imaged, and the focusing point is based on the imaging result. The amount of misalignment is detected, and the modulation pattern in the spatial light modulator is adjusted so that the misalignment is small.

Japanese Patent No. 662976

In the laser processing apparatus as described above, a branch pattern may be set in the spatial light modulator so that a plurality of modified regions are formed at the same time, and the laser beam may be branched according to the branch pattern. The branching pattern is set according to, for example, the output target value of each laser beam after branching. Here, in the case of branching, the output of each laser beam after branching matches the above-mentioned output target value due to the influence of individual differences in optical characteristics such as the passing regions of the branching lights in the lens being different from each other. Difficult to get. When the output of each laser beam after branching does not reach the expected value, the amount of cracks extending from the modified region does not become the desired amount of cracks, and undivided / unpeeled objects occur (processing quality deteriorates). ) There is a risk.

Therefore, it is an object of the present invention to provide a laser processing apparatus and a laser processing method capable of improving the processing quality by adjusting the output of the branched light to a desired value.

The laser processing apparatus according to one aspect of the present invention is a laser processing apparatus that forms a modified region on an object by irradiating the object with laser light, and is a light source that emits laser light and is emitted from the light source. A spatial light modulator that modulates the laser light, a condensing unit that collects the laser light modulated by the spatial light modulator on the object, and a detection unit that detects the reflected light of the laser light on the object. The control unit sets and displays the first branch pattern, which is a branch pattern for branching the laser light into a plurality of parts and corresponds to the output target value of each laser light after the branch, in the spatial optical modulator. 1 process, 2nd process to control the light source so that the laser light is emitted when the 1st branch pattern is displayed on the spatial light modulator, and reflected light of each laser light after branching by the 1st branch pattern. After branching, based on the third process that controls the detection unit so that It is configured to execute the fifth process of generating the second branch pattern in which the first branch pattern is corrected so that the output of each laser beam of the above is the output target value.

In the laser processing apparatus according to one aspect of the present invention, the reflected light in each object of the laser beam branched according to the first branch pattern is detected, and the reflected light of each laser beam after branching is detected based on the detection result. The brightness is derived. Here, the brightness of the reflected light of each laser beam after branching is proportional to the output (beam intensity) of each laser beam after branching. Therefore, by deriving the luminance, it is possible to estimate the output of each laser beam after branching with high accuracy. Then, after estimating the output of each laser beam after branching with high accuracy from the brightness, a new branching pattern (the first branching pattern is corrected so that the output of each laser beam after branching becomes the output target value). By generating the two-branch pattern), it is possible to generate a branch pattern that adjusts the output of each laser beam (branch light) after branching to a desired value (output target value). As described above, according to the laser processing apparatus according to one aspect of the present invention, the output of the branched light can be adjusted to a desired value and the processing quality can be improved. Further, once such a branch pattern correction process is performed, the corrected branch pattern (second branch pattern) is used for the subsequent laser machining, so that the branch pattern generation time can be reduced. can.

The control unit performs the sixth process of setting and displaying the second branch pattern on the spatial light modulator, and the laser beam is emitted while the second branch pattern is displayed on the spatial light modulator to process the object. The seventh process of controlling the light source and the like may be further executed. In this way, the branch pattern (second branch pattern) optimized based on the brightness is set in the spatial light modulator, and the laser processing is actually performed to adjust the output of the branch light to a desired value. In this state, high-quality processing of the object can be realized.

In the second process, the control unit may control the light source so that the laser beam is irradiated with an output at which the modified region is not formed on the object. This makes it possible to prevent the modified region from being formed on the object at the stage of adjusting the output of the branched light. This makes it possible to realize high-quality processing of the object.

The laser processing apparatus further includes an input unit that receives input from the user, and the control unit determines an output target value based on the information received by the input unit in the first process, and responds to the determined output target value. The first branch pattern may be set in the spatial light modulator. This makes it possible to set a branch pattern according to the conditions set by the user. That is, the laser processing desired by the user can be realized.

The condensing point of the laser light collected by the condensing unit is set on the surface which is the incident surface of the laser light on the object, and the detecting unit may detect the reflected light on the surface. The reflected light reflected on the surface has a relatively high brightness. By detecting such reflected light with high brightness, it is possible to estimate the output of the laser beam based on the brightness with higher accuracy.

The condensing point of the laser light collected by the condensing unit is set on the back surface, which is the surface opposite to the incident surface of the laser light on the object, and the detecting unit detects the reflected light on the back surface. May be good. When laser processing such as peeling processing is actually performed, a modulation pattern in which a light collection correction pattern other than the branch pattern is synthesized is set in the spatial light modulator. In terms of measuring the brightness of the branched light (output of each branched light) in consideration of the modulation pattern in the spatial light modulator during actual laser processing, the brightness of the reflected light on the back surface is measured. Is preferable. Therefore, by detecting the reflected light on the back surface, each branched light output can be adjusted to a desired value in consideration of the actual laser processing.

In the first process, the control unit may set the output target value of each laser beam after branching as a common value, and set and display the first branching pattern corresponding to the common value in the spatial light modulator. In branching, it may be desired to make the output of each laser beam after branching uniform. In such a case, as described above, the output target value of each laser beam after branching is set to a common value, and the output of each laser beam after branching is set to the common value in the fifth process. By generating the second branch pattern (that is, so that the output of each laser beam is made uniform), the variation in the output of each laser beam after branching is suppressed, and the output of each laser beam of the branched light is made uniform. Therefore, the processing quality can be improved.

The laser processing method according to one aspect of the present invention is a laser processing method for forming a modified region on an object by irradiating the object with laser light, and is a branching pattern in which the laser light is branched into a plurality of parts. The laser beam is emitted to the first step of setting and displaying the first branch pattern according to the output target value of each laser beam after branching in the spatial optical modulator and the spatial optical modulator displaying the first branch pattern. , The second step of irradiating the object with laser light branched into a plurality of pieces by the first branch pattern, the third step of detecting the reflected light of each laser beam after branching from the object, and the detection of the reflected light. Based on the result, the fourth step of deriving the brightness of the reflected light of each laser beam after branching, and the first branching pattern so that the output of each laser beam after branching becomes the above output target value based on the derived brightness. The fifth step of generating the second branch pattern corrected by the above is included.

According to the present invention, the processing quality can be improved by adjusting the output of the branched light to a desired value.

It is a perspective view of the laser processing apparatus of an embodiment. It is a front view of a part of the laser processing apparatus shown in FIG. It is a front view of the laser processing head of the laser processing apparatus shown in FIG. 1. It is a side view of the laser processing head shown in FIG. It is a block diagram of the optical system of the laser processing head shown in FIG. It is a top view for demonstrating a plurality of modification spots. It is a figure which shows an example of the setting screen of GUI. It is a figure which shows the example of the administrator mode of the setting screen of GUI. It is a figure explaining the laser processing which concerns on a comparative example. It is a table which shows the dent state of each branch light. It is a figure explaining the laser processing which concerns on embodiment. It is a figure explaining the laser processing which concerns on embodiment. It is a table which shows an example of the correction of a branch pattern based on the derived luminance and the result after the correction. It is a figure explaining the luminance measurement with the surface as a condensing point. It is a figure explaining the luminance measurement with the back surface as a condensing point. It is a schematic diagram which shows the laser processing state in the actual peeling processing. It is a figure explaining the determination of the luminance measurement height of the branch which is uniform in the Z direction. It is a figure explaining the determination of the luminance measurement height of a branch which is non-uniform in the Z direction. It is a flowchart which shows the correction process (the generation of a correction pattern) of a branch pattern. It is a figure which shows the formation state of the modification region and the crack extending from the modification region. It is a figure explaining the synthesis of AS pattern. It is a figure explaining the composition of a slit pattern. It is a figure explaining the composition of the horizontal branch pattern.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted.

First, the basic configuration of the laser processing device will be described.

[Basic configuration of laser processing equipment]
As shown in FIG. 1, the laser machining apparatus 1 includes a plurality of moving mechanisms 5 and 6, a support portion 7, a pair of laser machining heads 10A and 10B, a light source unit 8, and a control unit 9. ing. Although an example in which a pair of laser machining heads is used will be described below, only one laser machining head may be used. Hereinafter, the first direction is referred to as the X direction, the second direction perpendicular to the first direction is referred to as the Y direction, and the third direction perpendicular to the first direction and the second direction is referred to as the Z direction. In the present embodiment, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction.

The moving mechanism 5 has a fixed portion 51, a moving portion 53, and a mounting portion 55. The fixing portion 51 is attached to the device frame 1a. The moving portion 53 is attached to a rail provided on the fixed portion 51, and can move along the Y direction. The mounting portion 55 is mounted on a rail provided on the moving portion 53 and can move along the X direction.

The moving mechanism 6 has a fixing portion 61, a pair of moving portions 63, 64, and a pair of mounting portions 65, 66. The fixing portion 61 is attached to the device frame 1a. Each of the pair of moving portions 63 and 64 is attached to a rail provided on the fixed portion 61, and each of them can independently move along the Y direction. The mounting portion 65 is mounted on a rail provided on the moving portion 63 and can move along the Z direction. The mounting portion 66 is mounted on a rail provided on the moving portion 64 and can move along the Z direction. That is, with respect to the device frame 1a, each of the pair of mounting portions 65 and 66 can move along the Y direction and the Z direction, respectively.

The support portion 7 is attached to a rotation shaft provided on the mounting portion 55 of the moving mechanism 5, and can rotate about an axis parallel to the Z direction as a center line. That is, the support portion 7 can move along each of the X direction and the Y direction, and can rotate with the axis parallel to the Z direction as the center line. The support portion 7 supports the object 100. The object 100 is, for example, a wafer.

As shown in FIGS. 1 and 2, the laser machining head 10A is attached to the attachment portion 65 of the moving mechanism 6. The laser processing head 10A irradiates the object 100 supported by the support portion 7 with the laser beam L1 in a state of facing the support portion 7 in the Z direction. The laser machining head 10B is attached to the attachment portion 66 of the moving mechanism 6. The laser processing head 10B irradiates the object 100 supported by the support portion 7 with the laser beam L2 in a state of facing the support portion 7 in the Z direction.

The light source unit 8 has a pair of light sources 81 and 82. The light source 81 outputs the laser beam L1. The laser beam L1 is emitted from the emission unit 81a of the light source 81 and is guided to the laser processing head 10A by the optical fiber 2. The light source 82 outputs the laser beam L2. The laser beam L2 is emitted from the emission unit 82a of the light source 82, and is guided to the laser processing head 10B by another optical fiber 2.

The control unit 9 controls each unit (support unit 7, a plurality of moving mechanisms 5, 6, a pair of laser processing heads 10A, 10B, a light source unit 8, etc.) of the laser processing device 1. The control unit 9 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like. In the control unit 9, software (program) read into the memory or the like is executed by the processor, and reading and writing of data in the memory and storage, and communication by the communication device are controlled by the processor. As a result, the control unit 9 realizes various functions.

An example of processing by the laser processing apparatus 1 configured as described above will be described. An example of this processing is an example of forming a modified region inside the object 100 along a plurality of lines set in a grid pattern in order to cut the object 100, which is a wafer, into a plurality of chips. The laser processing device 1 may perform a peeling process for peeling a part of the object 100.

First, the moving mechanism 5 supports the support portion 7 along the X direction and the Y direction so that the support portion 7 supporting the object 100 faces the pair of laser machining heads 10A and 10B in the Z direction. Move it. Subsequently, the moving mechanism 5 rotates the support portion 7 with the axis parallel to the Z direction as the center line so that the plurality of lines extending in one direction in the object 100 are along the X direction.

Subsequently, the moving mechanism 6 moves the laser processing head 10A along the Y direction so that the condensing point (a part of the condensing region) of the laser beam L1 is located on one line extending in one direction. Move it. On the other hand, the moving mechanism 6 moves the laser processing head 10B along the Y direction so that the condensing point of the laser beam L2 is located on another line extending in one direction. Subsequently, the moving mechanism 6 moves the laser processing head 10A along the Z direction so that the condensing point of the laser beam L1 is located inside the object 100. On the other hand, the moving mechanism 6 moves the laser processing head 10B along the Z direction so that the condensing point of the laser beam L2 is located inside the object 100.

Subsequently, the light source 81 outputs the laser beam L1 and the laser processing head 10A irradiates the object 100 with the laser beam L1, while the light source 82 outputs the laser beam L2 and the laser processing head 10B lasers the object 100. Irradiate light L2. At the same time, the focusing points of the laser beam L1 move relatively along one line extending in one direction, and the focusing points of the laser beam L2 are relative to each other along the other lines extending in one direction. The moving mechanism 5 moves the support portion 7 along the X direction so as to move in a targeted manner. In this way, the laser machining apparatus 1 forms a modified region inside the object 100 along each of the plurality of lines extending in one direction in the object 100.

Subsequently, the moving mechanism 5 rotates the support portion 7 with the axis parallel to the Z direction as the center line so that a plurality of lines extending in the other direction orthogonal to one direction of the object 100 are along the X direction. ..

Subsequently, the moving mechanism 6 moves the laser processing head 10A along the Y direction so that the condensing point of the laser beam L1 is located on one line extending in the other direction. On the other hand, the moving mechanism 6 moves the laser processing head 10B along the Y direction so that the condensing point of the laser beam L2 is located on another line extending in the other direction. Subsequently, the moving mechanism 6 moves the laser processing head 10A along the Z direction so that the condensing point of the laser beam L1 is located inside the object 100. On the other hand, the moving mechanism 6 moves the laser processing head 10B along the Z direction so that the condensing point of the laser beam L2 is located inside the object 100.

Subsequently, the light source 81 outputs the laser beam L1 and the laser processing head 10A irradiates the object 100 with the laser beam L1, while the light source 82 outputs the laser beam L2 and the laser processing head 10B lasers the object 100. Irradiate light L2. At the same time, the focusing points of the laser beam L1 move relatively along one line extending in the other direction, and the focusing points of the laser beam L2 are relative to each other along the other line extending in the other direction. The moving mechanism 5 moves the support portion 7 along the X direction so as to move in a targeted manner. In this way, the laser machining apparatus 1 forms a modified region inside the object 100 along each of a plurality of lines extending in the other direction orthogonal to one direction in the object 100.

In one example of the above-mentioned processing, the light source 81 outputs the laser beam L1 having transparency to the object 100 by, for example, a pulse oscillation method, and the light source 82 is sent to the object 100 by, for example, a pulse oscillation method. On the other hand, the laser beam L2 having transparency is output. When such laser light is focused inside the object 100, the laser light is particularly absorbed at the portion corresponding to the focusing point of the laser light, and a modified region is formed inside the object 100. The modified region is a region in which the density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding non-modified region. The modified region includes, for example, a melt processing region, a crack region, a dielectric breakdown region, a refractive index change region, and the like.

When the laser beam output by the pulse oscillation method is applied to the object 100 and the focusing point of the laser light is relatively moved along the line set in the object 100, a plurality of modified spots are lined up. It is formed so as to line up in a row along the line. One modified spot is formed by irradiation with one pulse of laser light. A modification region in one row is a set of a plurality of modification spots arranged in one row. Adjacent modified spots may be connected to each other or separated from each other depending on the relative moving speed of the focusing point of the laser beam with respect to the object 100 and the repetition frequency of the laser beam. The shape of the line to be set is not limited to a grid shape, and may be an annular shape, a linear shape, a curved shape, or a shape in which at least one of these is combined.

[Laser machining head configuration]
As shown in FIGS. 3 and 4, the laser processing head 10A includes a housing 11, an incident unit 12, an adjusting unit 13, and a condensing unit 14.

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

In the laser processing head 10A, the first wall portion 21 is located on the side opposite to the fixed portion 61 of the moving mechanism 6, and the second wall portion 22 is located on the fixed portion 61 side. The third wall portion 23 is located on the mounting portion 65 side of the moving mechanism 6, and the fourth wall portion 24 is located on the opposite side of the mounting portion 65 and on the laser machining head 10B side (FIG. FIG. 2). The fifth wall portion 25 is located on the side opposite to the support portion 7, and the sixth wall portion 26 is located on the support portion 7 side.

The housing 11 is configured so that the housing 11 can be mounted on the mounting portion 65 in a state where the third wall portion 23 is arranged on the mounting portion 65 side of the moving mechanism 6. Specifically, it is as follows. The mounting portion 65 has a base plate 65a and a mounting plate 65b. The base plate 65a is attached to a rail provided on the moving portion 63 (see FIG. 2). The mounting plate 65b is erected at the end of the base plate 65a on the laser machining head 10B side (see FIG. 2). The housing 11 is attached to the mounting portion 65 by screwing the bolt 28 to the mounting plate 65b via the pedestal 27 in a state where the third wall portion 23 is in contact with the mounting plate 65b. The pedestal 27 is provided on each of the first wall portion 21 and the second wall portion 22. The housing 11 is removable from the mounting portion 65.

The incident portion 12 is attached to the fifth wall portion 25. The incident portion 12 causes the laser beam L1 to be incident inside the housing 11. The incident portion 12 is offset to the second wall portion 22 side (one wall portion side) in the X direction, and is offset to the fourth wall portion 24 side in the Y direction.

The incident portion 12 is configured so that the connection end portion 2a of the optical fiber 2 can be connected. The connection end 2a of the optical fiber 2 is provided with a collimator lens that collimates the laser beam L1 emitted from the emission end of the fiber, and is not provided with an isolator that suppresses the return light. The isolator is provided in the middle of the fiber which is on the light source 81 side of the connection end 2a. As a result, the connection end portion 2a is downsized, and the incident portion 12 is downsized. An isolator may be provided at the connection end 2a of the optical fiber 2.

The adjusting unit 13 is arranged in the housing 11. The adjusting unit 13 adjusts the laser beam L1 incident from the incident unit 12. Each configuration of the adjusting unit 13 is attached to an optical base 29 provided in the housing 11. The optical base 29 is attached to the housing 11 so as to partition the area inside the housing 11 into a region on the third wall portion 23 side and a region on the fourth wall portion 24 side. The optical base 29 is integrated with the housing 11. Each configuration of the adjusting portion 13 is attached to the optical base 29 on the fourth wall portion 24 side. The details of each configuration of the adjusting unit 13 will be described later.

The light collecting portion 14 is arranged on the sixth wall portion 26. Specifically, the light collecting portion 14 is arranged in the sixth wall portion 26 in a state of being inserted into the hole 26a formed in the sixth wall portion 26 (see FIG. 5). The light collecting unit 14 collects the laser beam L1 adjusted by the adjusting unit 13 and emits it to the outside of the housing 11. The light collecting portion 14 is offset to the second wall portion 22 side (one wall portion side) in the X direction, and is offset to the fourth wall portion 24 side in the Y direction.

As shown in FIG. 5, the adjusting unit 13 has an attenuator 31, a beam expander 32, and a mirror 33. The incident portion 12, the attenuator 31, the beam expander 32, and the mirror 33 of the adjusting portion 13 are arranged on a straight line (first straight line) A1 extending along the Z direction. The attenuator 31 and the beam expander 32 are arranged between the incident portion 12 and the mirror 33 on the straight line A1. The attenuator 31 adjusts the output of the laser beam L1 incident from the incident portion 12. The beam expander 32 expands the diameter of the laser beam L1 whose output is adjusted by the attenuator 31. The mirror 33 reflects the laser beam L1 whose diameter has been expanded by the beam expander 32.

The adjusting unit 13 further includes a reflective spatial light modulator 34 and an imaging optical system 35. The reflective spatial light modulator 34 and the imaging optical system 35 of the adjusting unit 13, and the condensing unit 14 are arranged on a straight line (second straight line) A2 extending along the Z direction. The reflective spatial light modulator 34 is, for example, a spatial light modulator (SLM: Spatial Light Modulator) of a reflective liquid crystal display (LCOS: Liquid Crystal on Silicon). The reflective spatial light modulator 34 modulates the laser beam L1 reflected by the mirror 33. The reflective spatial light modulator 34 modulates the laser beam L1 according to the displayed modulation pattern. In the reflection type spatial light modulator 34, at least a branch pattern for branching the laser beam L1 into a plurality of branches is set and displayed. As a result, the laser light L1 incident on the reflective spatial light modulator 34 is branched into a plurality of laser beams in the reflective spatial light modulator 34 (see FIG. 6, details will be described later). The imaging optical system 35 constitutes a bilateral telecentric optical system in which the reflecting surface 34a of the reflective spatial light modulator 34 and the entrance pupil surface 14a of the condensing unit 14 are in an imaging relationship. The imaging optical system 35 is composed of three or more lenses.

The straight line A1 and the straight line A2 are located on a plane perpendicular to the Y direction. The straight line A1 is located on the second wall portion 22 side (one wall portion side) with respect to the straight line A2. In the laser processing head 10A, the laser beam L1 enters the housing 11 from the incident portion 12, travels on the straight line A1, is sequentially reflected by the mirror 33 and the reflective spatial light modulator 34, and then the straight line A2. It travels upward and emits light from the light collecting unit 14 to the outside of the housing 11. The order of the arrangement of the attenuator 31 and the beam expander 32 may be reversed. Further, the attenuator 31 may be arranged between the mirror 33 and the reflective spatial light modulator 34. Further, the adjusting unit 13 may have other optical components (for example, a steering mirror arranged in front of the beam expander 32).

The laser processing head 10A further includes a dichroic mirror 15, a measurement unit 16, a detection unit 17, a drive unit 18, and a circuit unit 19.

The dichroic mirror 15 is arranged between the imaging optical system 35 and the condensing unit 14 on the straight line A2. That is, the dichroic mirror 15 is arranged between the adjusting unit 13 and the light collecting unit 14 in the housing 11. The dichroic mirror 15 is attached to the optical base 29 on the fourth wall portion 24 side. The dichroic mirror 15 transmits the laser beam L1. From the viewpoint of suppressing astigmatism, the dichroic mirror 15 is preferably, for example, a cube type or a two-plate type arranged so as to have a twisting relationship.

The measuring unit 16 is arranged in the housing 11 on the first wall portion 21 side (the side opposite to one wall portion side) with respect to the adjusting unit 13. The measuring unit 16 is attached to the optical base 29 on the side of the fourth wall unit 24. The measuring unit 16 outputs the measuring light L10 for measuring the distance between the surface of the object 100 (for example, the surface on the side where the laser light L1 is incident) and the condensing unit 14, and passes through the condensing unit 14. , The measurement light L10 reflected on the surface of the object 100 is detected. That is, the measurement light L10 output from the measurement unit 16 irradiates the surface of the object 100 via the condensing unit 14, and the measurement light L10 reflected on the surface of the object 100 passes through the condensing unit 14. Is detected by the measuring unit 16.

More specifically, the measurement light L10 output from the measurement unit 16 is sequentially reflected by the beam splitter 20 and the dichroic mirror 15 attached to the optical base 29 on the fourth wall unit 24 side, and is reflected from the condensing unit 14. It is emitted to the outside of the housing 11. The measurement light L10 reflected on the surface of the object 100 is incident on the housing 11 from the condensing unit 14 and is sequentially reflected by the dichroic mirror 15 and the beam splitter 20 and is incident on the measurement unit 16 to be incident on the measurement unit 16. Is detected by.

The detection unit 17 is arranged in the housing 11 on the first wall portion 21 side (the side opposite to one wall portion side) with respect to the adjustment unit 13. The detection unit 17 is attached to the optical base 29 on the side of the fourth wall portion 24. The detection unit 17 outputs the observation light L20 for observing the surface of the object 100 (for example, the surface on the side where the laser beam L1 is incident) and reflects the light L20 on the surface of the object 100 via the condensing unit 14. The observed light L20 is detected. That is, the observation light L20 output from the detection unit 17 irradiates the surface of the object 100 via the condensing unit 14, and the observation light L20 reflected on the surface of the object 100 passes through the condensing unit 14. Is detected by the detection unit 17. The detection unit 17 is, for example, a camera that detects (imaging) the reflected observation light L20.

More specifically, the observation light L20 output from the detection unit 17 passes through the beam splitter 20 and is reflected by the dichroic mirror 15, and is emitted from the condensing unit 14 to the outside of the housing 11. The observation light L20 reflected on the surface of the object 100 enters the housing 11 from the condensing unit 14, is reflected by the dichroic mirror 15, passes through the beam splitter 20 and is incident on the detection unit 17, and is incident on the detection unit 17. It is detected at 17. The wavelengths of the laser light L1, the measurement light L10, and the observation light L20 are different from each other (at least the center wavelengths of the laser light L1 are deviated from each other).

Further, the detection unit 17 detects a part of the laser beam L1 reflected on the surface of the object 100 (details will be described later). The part of the laser beam L1 reflected on the surface of the object 100 is the laser beam L1 reflected on the surface of the object 100 in a small amount in the direction of the detection unit 17 by the dichroic mirror 15. Is.

The drive unit 18 is attached to the optical base 29 on the side of the fourth wall portion 24. The driving unit 18 moves the light collecting unit 14 arranged on the sixth wall unit 26 along the Z direction by, for example, the driving force of the piezoelectric element.

The circuit portion 19 is arranged on the third wall portion 23 side with respect to the optical base 29 in the housing 11. That is, the circuit unit 19 is arranged in the housing 11 on the third wall unit 23 side with respect to the adjusting unit 13, the measuring unit 16, and the detection unit 17. The circuit unit 19 is, for example, a plurality of circuit boards. The circuit unit 19 processes the signal output from the measurement unit 16 and the signal input to the reflection type spatial light modulator 34. The circuit unit 19 controls the drive unit 18 based on the signal output from the measurement unit 16. As an example, the circuit unit 19 is such that the distance between the surface of the object 100 and the condensing unit 14 is kept constant (that is, with the surface of the object 100) based on the signal output from the measuring unit 16. The drive unit 18 is controlled so that the distance of the laser beam L1 from the condensing point is kept constant). The housing 11 is provided with a connector (not shown) to which wiring for electrically connecting the circuit unit 19 to the control unit 9 (see FIG. 1) or the like is connected.

Similar to the laser processing head 10A, the laser processing head 10B includes a housing 11, an incident unit 12, an adjusting unit 13, a condensing unit 14, a dichroic mirror 15, a measuring unit 16, and a detecting unit 17. A drive unit 18 and a circuit unit 19 are provided. However, as shown in FIG. 2, each configuration of the laser machining head 10B is different from each configuration of the laser machining head 10A with respect to a virtual plane passing through the midpoint between the pair of mounting portions 65 and 66 and perpendicular to the Y direction. They are arranged so as to have a plane-symmetrical relationship.

For example, in the housing (first housing) 11 of the laser machining head 10A, the fourth wall portion 24 is located on the laser machining head 10B side with respect to the third wall portion 23, and the sixth wall portion 26 is the fifth wall. It is attached to the attachment portion 65 so as to be located on the support portion 7 side with respect to the portion 25. On the other hand, in the housing (second housing) 11 of the laser machining head 10B, the fourth wall portion 24 is located on the laser machining head 10A side with respect to the third wall portion 23, and the sixth wall portion 26 is the third. It is attached to the attachment portion 66 so as to be located on the support portion 7 side with respect to the wall portion 25.

The housing 11 of the laser processing head 10B is configured so that the housing 11 is mounted on the mounting portion 66 with the third wall portion 23 arranged on the mounting portion 66 side. Specifically, it is as follows. The mounting portion 66 has a base plate 66a and a mounting plate 66b. The base plate 66a is attached to a rail provided on the moving portion 63. The mounting plate 66b is erected at the end of the base plate 66a on the laser machining head 10A side. The housing 11 of the laser processing head 10B is attached to the mounting portion 66 in a state where the third wall portion 23 is in contact with the mounting plate 66b. The housing 11 of the laser processing head 10B is removable from the mounting portion 66.

[Branch pattern correction processing]
In the following, when the laser beam is branched to irradiate the object 100 for the purpose of cutting and peeling the object 100, the reflected spatial light is set so that the output of each branched laser beam becomes the output target value. The process of correcting the branch pattern set and displayed on the modulator 34 will be described. In the following, mainly, the output target value of each branched laser beam is set to a common value, and the output of each branched laser beam is set to the common value (that is, the output of each laser beam). The process of correcting the branch pattern (so that is made uniform) will be described. The correction process is performed before the modified region is formed on the object 100 for the purpose of cutting the object or the like.

First, the branching of the laser beam L1 will be described with reference to FIGS. 6 to 8. As described above, the laser beam L1 is branched according to the branching pattern set and displayed on the reflective spatial light modulator 34.

FIG. 6 is a diagram illustrating a plurality of modified spots SA when the laser beam L1 is branched into four. In the example shown in FIG. 6, a plurality of (four) modified spots SA arranged in a row along the inclination direction C2 inclined with respect to the orthogonal direction orthogonal to the machining progress direction C1 are formed on the object 100. The laser beam L1 is branched. The branching of the laser beam L1 is realized by a branching pattern (modulation pattern) set and displayed on the reflective spatial light modulator 34 (see FIG. 5).

In the illustrated example, the laser beam L1 is branched into four to form four modified spots SA. For a pair of adjacent modified spots SA among the four branched modified spots SA, the interval in the machining progress direction C1 is the branch pitch BPx, and the interval in the orthogonal direction of the machining progress direction C1 is the branch pitch BPy. For the pair of modified spots SA formed by irradiation of two consecutive pulses of laser light L1, the interval in the machining progress direction C1 is the pulse pitch PP. The angle between the machining progress direction C1 and the inclination direction C2 is the branch angle α.

FIG. 7 is a setting screen of the GUI 111 for realizing branching of the laser beam L1 as shown in FIG. The GUI 111 functions as an input unit that receives input from the user. The GUI 111 setting screen shown in FIG. 7 has a machining condition selection button 211 for selecting machining conditions, a branch number column 212 for inputting or selecting the number of branches of the laser beam L1, and a laser along one machining line. The index field 213 for inputting the index which is the distance to move to the next processing line after processing, the image FIG. 214 for inputting or displaying the number of branches and the index, and the position of the modified spot SA in the Z direction are input. It includes a machining Z height column 215, a machining speed column 216 for inputting a machining speed, and a condition switching method button 217 for selecting a machining condition switching method.

With the machining condition selection button 211, specific machining conditions can be selected from a plurality of options. According to the index column 213, when the number of branches is 1, the laser machining head 10A is automatically moved in the index direction by the input value. When the number of branches is larger than 1, the laser machining head 10A is automatically moved in the index direction only by the index based on the following formula.
Index = (number of branches) x index input value

Image FIG. 214 includes an index input value display unit 214a and an output input field 214b for inputting the output of each modified spot SA.

FIG. 8 is a diagram showing an example of the administrator mode of the setting screen of the GUI 111. The setting screen shown in FIG. 8 has a branch direction selection button 221 for selecting the branch direction of the laser beam L1, a branch number field 222 for inputting or selecting the number of branches of the laser beam L1, and a branch pitch for inputting the branch pitch BPx. Input field 223, branch pitch number input field 224 for inputting the number of branches of branch pitch BPx, branch pitch input field 225 for inputting branch pitch BPy, index field 226 for inputting index, and light based on the number of branches. Axis image FIG. 227, an outward return path selection button 228 that selects whether the scanning direction of the laser beam L1 is one direction (outward path) or another direction (return path), and a balance adjustment start button 229 that automatically adjusts the balance of various numerical values. ,including.

The control unit 9 determines the output target value of each laser beam after branching (here, a value common to each laser beam after branching) based on the information received from the user in the GUI 111, and responds to the determined output target value. Further, a first branch pattern (modulation pattern) for branching the laser beam L1 is derived. In this case, the control unit 9 may select one branch pattern from a plurality of branch patterns prepared in advance and use it as the first branch pattern, or generate a new branch pattern based on the information received from the user. It may be the first branch pattern. The control unit 9 sets the derived first branch pattern in the reflection type spatial light modulator 34 and displays it.

As shown in FIG. 9A, when information for branching the laser beam L1 into four branches is input to the GUI 111, the control unit 9 controls each branch processing point (each condensing point of the branched laser light). ), The output target value is determined so that the laser outputs are comparable to each other (see FIG. 9B), and the first branch pattern 340 is generated (automatically generated) according to the determined output target value. The first branch pattern 340 is set and displayed on the reflective spatial light modulator 34 (see FIG. 9C). In the graphs of FIGS. 9 (b), 9 (e), 11 (b), 11 (e), 12 (b), and 12 (d), each of the branches related to the laser beam. The output of the laser light (or the brightness of the reflected light) for the focusing point is shown. Then, as shown in FIG. 9D, the laser beam L1 is branched according to the first branch pattern 340 and irradiated to the object 100 to perform processing (automatic processing) of the object 100. Here, although each laser beam obtained by branching the laser beam L1 according to the first branch pattern 340 is theoretically set to have the same output, it is actually shown in FIG. 9 (e). As shown, it is conceivable that the outputs (actual input outputs) are not comparable to each other.

FIG. 10 is a table showing an example of a dent state (specifically, whether or not a modified region is generated) when the laser beam L1 is branched into four according to the first branch pattern and irradiated to the object 100. In FIG. 10, for each of the four branched laser beams, the theoretical pulse energy value and whether or not a modified region has occurred (“◯” if it has occurred, and “〇” if it has not occurred, if it has not occurred. Indicates "x"). As shown in FIG. 10, even when the laser beam L1 is branched by the first branch pattern set so that the output of each branch light is about the same, the light collection point 2 and the light collection point 3 are divided. In the branched light, the modified region is generated when the pulse energy is 5.71 μj or more, whereas in the branched light at the condensing point 3, the modified region is generated when the pulse energy is 5.96 μj or more. Further, in the branched light at the condensing point 1, a modified region is generated when the pulse energy is 6.48 μj or more. As described above, even when the laser beam L1 is branched so that the outputs of the branched lights are about the same, the laser outputs of the branched lights may not be about the same as each other. Such a difference in laser output is caused by the influence of individual differences in optical characteristics such as different regions of passage of each branched light in the lens, and it is difficult to completely eliminate the influence of such individual differences. Is. Moreover, it is difficult to grasp such individual differences without actually performing laser irradiation.

Therefore, in the laser processing apparatus 1 according to the present embodiment, the target object 100 is irradiated with the laser light branched by the first branching pattern in the stage before the processing process for forming the modified region on the object 100 is performed. The reflected light of the laser beam is detected (imaging) to derive the brightness, and the correction process for correcting the first branch pattern is performed based on the brightness. Specifically, the laser processing apparatus 1 estimates the output of each branched light based on the brightness, and the output of the branched light becomes the output target value (here, the output of each branched light is made uniform). , The first branch pattern is corrected and a new branch pattern, the second branch pattern, is generated.

The correction process is based on the premise that the brightness of the reflected light of the branched light detected (imaging) is proportional to the output (beam intensity) of the branched light. In the example of FIG. 10 described above, assuming that the pulse energies of the condensing point 2 and the condensing point 3 where the modified region is generated when the pulse energy is 5.71 μj or more are 100% (maximum intensity), they are relative to each other. When the pulse energy is 5.96 μj or more, the pulse energy of the focusing point 4 where the modified region is generated is 96%, and when the pulse energy is 6.48 μj or more, the modified region is generated. The pulse energy at point 1 can be regarded as 88%. In this case, the brightness of the reflected light of the branched light detected (imaged) by the detection unit 17 is collected assuming that the brightness of the largest focusing point 3 is 100% as shown in FIG. 13 (a). The light point 1 was 89%, the light collection point 2 was 98%, and the light collection point 4 was 96%. As a result, it can be said that there is a proportional relationship between the brightness of the reflected light and the output of the light condensing point 1 and the condensing point 3, although there is a slight difference between the intensity and the output of the reflected light. Therefore, by estimating the output of each branched light based on the brightness and correcting the first branch pattern so that the output of the branched light is made uniform, the variation in the output of the branched light during laser processing is appropriate. Can be reduced to.

11 and 12 are diagrams illustrating the processing of the laser processing apparatus 1 that performs the above-mentioned correction processing. As shown in FIG. 11A, when information for branching the laser beam L1 into four branches is input to the GUI 111, the control unit 9 controls each branch processing point (each condensing point of the branched laser light). The first branch pattern 340 is generated (automatically generated) so that the laser outputs in (1) are theoretically comparable to each other (see FIG. 11 (b)), and the first branch pattern 340 is a reflection type spatial light modulator. It is set and displayed in 34 (see FIG. 11 (c)). Then, the laser beam L1 is branched according to the first branch pattern 340, each branch light is irradiated to the object 100, and the reflected light of each branch light in the object 100 is detected (imaged) by the detection unit 17. (See FIG. 11 (d)). As shown in FIG. 11 (d), the control unit 9 derives the luminance of the detected reflected light, and the luminance of each point (the luminance of each branched light) is compared (see FIG. 11 (e)). ..

Then, the control unit 9 generates a second branch pattern 341 in which the first branch pattern 340 is corrected so that the output of the branch light is made uniform based on the derived luminance, and the second branch pattern 341 is a reflection type. It is set and displayed on the spatial light modulator 34 (see FIG. 12A). In this case, as shown in FIG. 12B, as the second branch pattern 341, the output of the branch light having a relatively low brightness is increased as compared with the branch light having a relatively high brightness. The modulation pattern is set to. Specifically, for example, regarding the brightness of the reflected light of each branched light, as shown in FIG. 13A, the brightness of the focusing point 1 is 89%, where the brightness of the largest focusing point 3 is 100%. Assuming that the brightness of the focusing point 2 is 98% and the brightness of the focusing point 4 is 96%, as shown in FIG. 13B, the magnitude and difference of the brightness are taken into consideration for the second branch pattern. Then, assuming that the pulse energy of the condensing point 1 is 100% (maximum intensity), the pulse energy of the condensing point 2 is 91%, the pulse energy of the condensing point 3 is 89%, and the pulse energy of the condensing point 4 is Is adjusted to be 93%. In this example, the second branch is such that the value obtained by multiplying the% value of the luminance before correction and the% value of the pulse energy of the second branch pattern (after correction) are about the same for all the focusing points. A pattern has been generated.

The laser beam L1 is branched by using the second branch pattern 341 set in this way, and the object 100 is processed by irradiating the object 100 with the branched light (see FIG. 12 (c)). ). In this case, as shown in FIG. 12 (d), the object 100 is processed with the outputs (actual input outputs) of the branched lights at the time of processing being set to the same level. For example, when the luminance is measured as shown in FIG. 13 (a) and the branch pattern is corrected as shown in FIG. 13 (b), as shown in FIG. 13 (c). At any of the focusing points, a modified region is generated when the pulse energy is 5.71 μj or more. In this way, the output of each branch light is made uniform by the second branch pattern, so that the conditions for generating the modified region for each branch light can be made the same. As a result, it is possible to suppress the variation in the amount of cracks extending from the modified region, suppress the occurrence of undivided / unpeeled objects, and improve the processing quality.

Hereinafter, the function of the control unit 9 that realizes the branch pattern correction process described above will be described.

The control unit 9 is a branch pattern in which the laser light L1 is branched into a plurality of branches, and the first branch pattern corresponding to the output target value of each laser light after branching is set in the reflection type spatial light modulator 34 and displayed. The processing, the second processing for controlling the light source unit 8 so that the laser beam L1 is emitted in the state where the first branch pattern is displayed on the reflection type spatial light modulator 34, and each after branching by the first branch pattern. The third process of controlling the detection unit 17 so that the reflected light of the laser light is detected, and the fourth process of deriving the brightness of the reflected light of each laser light after branching based on the detection result by the detection unit 17, and the derivation. Based on the brightness, the fifth process of generating a second branch pattern in which the first branch pattern is corrected so that the output of each laser beam after branching becomes an output target value is executed.

In the first process, the control unit 9 determines the output target value based on the information received on the setting screen of the GUI 111 (see FIGS. 7 and 8), and reflects the first branch pattern according to the determined output target value. It is set in the type spatial light modulator 34. The control unit 9 sets the output target value of each laser beam after branching as a common value, and sets and displays the first branching pattern corresponding to the common value in the reflection type spatial light modulator 34. In this case, the first branching pattern is theoretically a branching pattern in which the outputs of the laser beams after branching are about the same as each other.

In the second process, the control unit 9 receives the laser beam L1 at an output (below the modification threshold) at which the modification region is not formed on the object 100 in a state where the first branch pattern is displayed on the reflection type spatial light modulator 34. The light source unit 8 is controlled so that the light source unit 8 is irradiated. The laser beam after branching may be applied to an object (object for correction processing) different from the object 100 to be laser-processed after the branch pattern correction process.

Here, in the second process, the control unit 9 controls the moving mechanism 6 so that the laser processing head 10A moves along the Z direction, so that the focusing point of each laser beam after branching is set as an object. It may be set on the surface 100a (see FIG. 14) which is the incident surface of the 100 laser beam. In this case, the detection unit 17 detects the reflected light on the surface 100a. The reflected light reflected on the surface 100a has a relatively high brightness. By detecting such reflected light with high brightness, it is possible to accurately estimate the output of the laser beam based on the brightness.

Alternatively, the control unit 9 controls the moving mechanism 6 so that the laser processing head 10A moves along the Z direction, so that the condensing point of each laser beam after branching is set to the incident surface of the laser beam of the object 100. It may be set to the back surface 100b (see FIG. 15) which is the opposite surface of the front surface 100a. In this case, the detection unit 17 detects the reflected light on the back surface 100b. FIG. 16 is a schematic diagram showing a laser processing state in actual peeling processing. As shown in FIG. 16, when laser processing such as peeling processing is actually performed, the reflective spatial light modulator 34 has not only the branch pattern but also the depth (Z height) of the condensing point. A modulation pattern in which the corresponding light collection correction pattern and the like are combined is set. In this regard, as shown in FIG. 15, when the back surface 100b is used as a focusing point, the reflective spatial light modulator 34 has a branch pattern, a focusing correction pattern according to the thickness t of the object 100, and the like. Since the combined modulation pattern is set and the brightness is detected, the light of each laser beam after branching is taken into consideration in consideration of the light collection correction pattern, as in the case of laser processing such as actual peeling processing. The brightness of the reflected light can be detected. This makes it possible to determine the brightness (that is, the laser output) in an environment similar to that during actual laser processing.

The control unit 9 determines the brightness measurement height based on the intensity of the reflected light detected (imaging) by the detection unit 17 while moving the laser machining head 10A in the Z direction by controlling the movement mechanism 6. You may. That is, as shown in FIG. 17, when the branching light is branched to the same height in the Z direction, the control unit 9 brightens the Z height at which the intensity (luminance) of all the branched light increases. The measurement height may be determined. Further, as shown in FIG. 18, when each branched light is branched to different heights in the Z direction, the control unit 9 measures the luminance of the Z height at which the intensity increases for each branched light. You may decide on the height. If the deviation amount of the condensing position can be specified in advance, the control unit 9 may determine the final luminance measurement height in consideration of the deviation amount for the determined luminance measurement height. The amount of deviation is, for example, deviation due to chromatic aberration of the objective lens of the reticle used at the time of height setting.

In the third process, the control unit 9 can detect (imaging) the reflected light of each laser beam after branching in the object 100, at least during the period in which each laser beam after branching is irradiated to the object 100. The detection unit 17 is controlled so as to be. The control unit 9 acquires an image captured by the detection unit 17 from the detection unit 17.

In the fourth process, the control unit 9 identifies a region having a higher brightness than the other regions in the image pickup data acquired by the detection unit 17 by the number of branches. The region here is a region including a peripheral region centered on the point having the highest luminance. Then, the control unit 9 derives the brightness of the region corresponding to each branched light in consideration of the ambient brightness.

The control unit 9 further performs a sixth process of setting and displaying the second branch pattern on the reflection type spatial light modulator 34, and a laser beam L1 in a state where the second branch pattern is displayed on the reflection type spatial light modulator 34. Is emitted to control the light source unit 8 so that the object 100 is processed, and the seventh process is further executed.

Next, the branch pattern correction process will be described with reference to the flowchart of FIG.

As shown in FIG. 19, in the branch pattern correction process, first, the first branch pattern is derived based on the information received on the setting screen of the GUI 111, and the first branch pattern is transferred to the reflection type spatial light modulator 34. Set and displayed (step S1: first step).

Subsequently, the laser beam L1 is emitted to the reflective spatial light modulator 34 on which the first branch pattern is displayed, and the laser beam branched into a plurality of pieces by the first branch pattern irradiates the front surface 100a or the back surface 100b of the object 100. (Step S2: second step).

Subsequently, the reflected light of the branched light from the front surface 100a or the back surface 100b is detected (imaged) by the detection unit 17 (step S3: third step). Then, the brightness at the condensing point of each laser beam after branching is measured based on the imaging data (detection result of reflected light) (step S4: fourth step).

Finally, based on the derived luminance data, the output of each laser beam after branching is set to the output target value (so that the output is made uniform when the output target values are common values). A correction pattern (second branch pattern) corrected from the first branch pattern is generated (step S5: fifth step).

Next, the operation and effect of the laser processing apparatus 1 according to the present embodiment will be described.

The laser processing apparatus 1 according to the present embodiment is a laser processing apparatus that forms a modified region on the object 100 by irradiating the object 100 with a laser beam, and is a light source unit 8 that emits the laser light and a light source. A reflective space light modulator 34 that modulates the laser light emitted from the unit 8, a condensing unit 14 that condenses the laser light modulated by the reflective space light modulator 34 onto the object 100, and an object 100. A detection unit 17 for detecting the reflected light of the laser light in the above and a control unit 9 are provided, and the control unit 9 has a branch pattern in which the laser light is branched into a plurality of branches, and the output target value of each laser light after the branch is set. The first process of setting and displaying the corresponding first branch pattern on the reflection type space light modulator 34, and the laser light being emitted in the state where the first branch pattern is displayed on the reflection type space light modulator 34. Based on the second process of controlling the light source unit 8, the third process of controlling the detection unit 17 so that the reflected light of each laser beam after branching by the first branch pattern is detected, and the detection result by the detection unit 17. The fourth process of deriving the brightness of the reflected light of each laser beam after branching, and the second process in which the first branching pattern is corrected so that the output of each laser beam after branching becomes the output target value based on the derived brightness. It is configured to execute the fifth process of generating a branch pattern.

In the laser processing apparatus 1 according to the present embodiment, the reflected light of each laser beam branched according to the first branch pattern in the object 100 is detected, and the reflected light of each laser beam after branching is detected based on the detection result. The brightness is derived. Here, the brightness of the reflected light of each laser beam after branching is proportional to the output (beam intensity) of each laser beam after branching. Therefore, by deriving the luminance, it is possible to estimate the output of each laser beam after branching with high accuracy. Then, after estimating the output of each laser beam after branching with high accuracy from the brightness, a new branching pattern (the first branching pattern is corrected so that the output of each laser beam after branching becomes the output target value). By generating the two-branch pattern), it is possible to generate a branch pattern that adjusts the output of each laser beam (branch light) after branching to a desired value (output target value). As described above, according to the laser processing apparatus 1 according to the present embodiment, the output of the branched light can be adjusted to a desired value and the processing quality can be improved.

The control unit 9 emits laser light in the sixth process of setting and displaying the second branch pattern on the reflection type spatial light modulator 34 and in the state where the second branch pattern is displayed on the reflection type spatial light modulator 34. The seventh process of controlling the light source unit 8 so that the object 100 is processed may be further executed. In this way, the branch pattern (second branch pattern) optimized based on the luminance is set in the reflection type spatial light modulator 34, and the laser processing is actually performed, so that the output of the branch light is desired. High-quality processing of the object 100 can be realized in a state adjusted to the value.

In the second process, the control unit 9 may control the light source unit 8 so that the laser beam is irradiated with an output at which the modification region is not formed on the object 100. This makes it possible to prevent the modified region from being formed on the object 100 at the stage of adjusting the output of the branched light. This makes it possible to realize high-quality processing of the object 100.

The laser processing apparatus 1 further includes a GUI 111 that receives input from the user, and the control unit 9 determines an output target value based on the information received by the GUI 111 in the first process, and responds to the determined output target value. The first branch pattern may be set in the reflection type spatial light modulator 34. This makes it possible to set a branch pattern according to the conditions set by the user. That is, the laser processing desired by the user can be realized.

The condensing point of the laser light collected by the condensing unit 14 is set on the surface 100a, which is the incident surface of the laser light on the object 100, and the detecting unit 17 detects the reflected light on the surface 100a. May be good. The reflected light reflected on the surface 100a has a relatively high brightness. By detecting such reflected light with high brightness, it is possible to estimate the output of the laser beam based on the brightness with higher accuracy.

The condensing point of the laser light collected by the condensing unit 14 is set on the back surface 100b, which is the opposite surface of the front surface 100a of the object 100, and the detecting unit 17 detects the reflected light on the back surface 100b. You may. When laser processing such as peeling processing is actually performed, a modulation pattern in which a light collection correction pattern other than the branch pattern is synthesized is set in the reflection type spatial light modulator 34. In terms of measuring the brightness of the branched light (output of each branched light) in consideration of the modulation pattern in the reflective spatial light modulator 34 during actual laser processing, the brightness of the reflected light on the back surface 100b is the same. It is preferable to be measured. Therefore, by detecting the reflected light on the back surface 100b, the output of each branched light can be adjusted to a desired value in consideration of the actual laser processing.

Then, as mainly described in the present embodiment, in the first process, the control unit 9 sets the output target value of each laser beam after branching as a common value, and the first branching pattern corresponding to the common value. May be set in the reflective spatial light modulator 34 and displayed. In branching, it may be desired to make the output of each laser beam after branching uniform. In such a case, as described above, the output target value of each laser beam after branching is set to a common value, and the output of each laser beam after branching is set to the common value in the fifth process. By generating the second branch pattern (that is, so that the output of each laser beam is made uniform), the variation in the output of each laser beam after branching is suppressed, and the output of each laser beam of the branched light is made uniform. Therefore, the processing quality can be improved.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the output target value of each branched laser beam is mainly set to a common value, and the output of each branched laser beam is set to the common value (that is, each laser beam). Although it has been described as generating a second branch pattern (so that the output of the laser beam is made uniform), the present invention is not limited to this, and the output target values of the branched laser beams may be different from each other. Also in this case, the output of the branched light is adjusted to a desired value by generating a second branch pattern so that the output of each laser beam after branching becomes the respective output target value based on the brightness. Processing quality can be improved.

Further, for example, the object 100 for which the luminance measurement is performed may be a mirror wafer (bare wafer without a pattern) or an actual device (wafer with a pattern) on which peeling processing or the like is actually performed. good. In an actual device, a laminated film such as SiN or SiO2 may be provided on the laser incident surface side, but it is considered that the reflectance is lower than that of the mirror wafer due to the influence of multiple reflections on the laminated film. For example, in a mirror wafer, the reflectance of a laser having a wavelength of 1099 nm is about 30%, whereas in a real device provided with a SiN film of 100 nm, the reflectance of a laser having the same wavelength is reduced to about 8%. Therefore, in such an actual device, it is conceivable that the measured luminance value is lowered. In this respect, for example, in the case of specifying the variation in the output of each branched light, it is sufficient that the relative brightness of each point can be compared, so that the decrease in the measured luminance due to the decrease in the reflectance does not matter much. However, when the amount of reflected light is so low that the brightness cannot be measured, it is necessary to make a correction to increase the laser output at the time of measurement. In this case, the attenuator may be changed while monitoring the luminance value to set the output that becomes the optimum luminance value for measurement, or the luminance value (reflectance) and the optimum luminance value of the mirror wafer may be grasped in advance. , You may adjust the output for the deviation from there.

When the above-mentioned seventh process (processing of an object by laser light) is performed using an actual device, the output setting correction may be performed in consideration of the above-mentioned reflectance.

As described above, as an example of laser processing using the laser processing apparatus 1, in order to cut the object 100, which is a wafer, into a plurality of chips, the object 100 is formed along a plurality of lines set in a grid pattern. Examples include processing for forming a modified region inside. An example of the processing conditions of the processing is shown below. In the processing, it is assumed that two rows of modified regions are formed in the object 100 in the thickness direction. The two rows of modified regions may be formed by separately irradiating the laser beam, or may be formed by bifurcating the processing points using a bifocal branching pattern in one scan.

Material to be processed: Silicon wafer, Wafer thickness: 300 μm, Crystal orientation: <100>, Resistance value: 1 Ω · cm or more Laser wavelength of laser processing device 1: 1099 nm, Pulse width: 700 nsec, Frequency: 120 kHz, Stage speed: 800 mm / sec, pulse pitch: 6.67 μm
Depth of condensing point (Z height) of SD1 which is a modified region on the side far from the incident surface (Z height): Z64, output: 2.78 W, display pattern of spatial light modulator: spherical aberration correction pattern is used. Depth of condensing point (Z height) of SD2, which is the modified region on the side (Z height): Z24, output: 1.85W, display pattern of spatial light modulator: spherical aberration correction pattern is used.

FIG. 20A is a diagram showing a state of formation of cracks 14 extending from the modified regions 12a and 12b and the modified regions 12a and 12b when the object 100 is processed under the above-mentioned processing conditions. In the example shown in FIG. 20 (a), it cannot be said that the formation state of the cracks 14 extending from the modified regions 12a and 12b and the modified regions 12a and 12b is good. Specifically, when compared with the formation state of the cracks 14 extending from the modified regions 12a and 12b and the modified regions 12a and 12b as shown in FIG. 20 (b), the cracks 14 and the like shown in FIG. 20 (a) and the like. The formation state of is not good. By satisfactorily forming cracks 14 and the like as shown in FIG. 20 (b), unevenness (unevenness on the end face) at the time of cutting is reduced, and cutting with high straightness is possible. In addition, by suppressing the unevenness of the end face, there is an effect of preventing crack residue at the time of division, an effect of reducing the generation rate of modified layer pieces (silicon particles) generated from the cut surface, an effect of increasing the bending strength, and the like. .. In the following, in order to realize the formation state of the crack 14 and the like as shown in FIG. 20 (b), in addition to the above-mentioned processing conditions, a predetermined pattern is further synthesized in the spatial light modulator, and the predetermined pattern is formed. An example of processing in the displayed state will be described.

FIG. 21 is a diagram illustrating an example of synthesizing an AS pattern, which is a pattern for adding astigmatism, as the above-mentioned predetermined pattern. FIG. 21 shows the shape of the beam L150 at the condensing point. In the example shown in FIG. 21, the intensity distribution of the beam L150 is elliptical, and more specifically, the machining progress direction is an elliptical shape by synthesizing the AS pattern, which is a pattern for adding astigmatism. There is. When the major axis ÷ minor axis of the beam shape is the ellipticity, the ellipticity of the elliptic shape is, for example, 1.5. In this way, the beam of the laser beam is formed into an elliptical shape in the processing progress direction by synthesizing the AS pattern, so that cutting with higher straightness is possible. The effect of enhancing straightness is achieved, for example, by setting the ellipticity to 1.05 or more.

FIG. 22 is a diagram illustrating an example of synthesizing a slit pattern as the predetermined pattern described above. The slit pattern here is a pattern that cuts both ends of the laser beam in the direction intersecting the processing progress direction. That is, for example, when the processing progress direction is the left-right direction, the slit pattern cuts the vertical end portion of the beam of the laser beam. In the example shown in FIG. 22, the upper and lower ends of the beam L180 are cut by the slit patterns 500 and 600 when the processing progress direction is from the left to the right in the figure. The size of the region to be cut here may be, for example, about 10% of the entire beam. In this way, by synthesizing the slit pattern that cuts both ends in the direction intersecting the machining progress direction, the beam shape of the laser incident surface becomes long in the machining progress direction, so that cutting with high straightness is possible. Will be.

FIG. 23 is a diagram illustrating an example of synthesizing a horizontal branch pattern as the above-mentioned predetermined pattern. The term "lateral branching" here means that the laser beam is branched in a direction that intersects the thickness direction (Z direction) of the object 100, and more specifically, that the laser beam is branched in the processing progress direction. In the example shown in FIG. 23, the horizontal branching pattern in which the beam is branched in the machining progress direction is synthesized while the pulse pitch is 6.67 μm, and the distance between the two branched beams is 3 μm. A horizontal branch pattern is set. In this case, the distance between the beams L201 and L202 branched into two is 3 μm, the distance (pulse pitch) between the beams L201 and L203 is 6.67 μm, and the distance between the beams L203 and L204 branched into two. Is 3 μm. In this way, the straightness described above can be improved by processing so as to laterally branch at a distance smaller than the pulse pitch.

Although each predetermined pattern as described above can be used alone to improve straightness, it may be possible to further improve straightness by using each of them in combination. It should be noted that the effect of the predetermined pattern described above may be realized without using a spatial light modulator. That is, for example, a cylindrical lens may realize the same effect as the AS pattern, or a mechanical blade may cut the beam end portion to realize the same effect as the slit pattern.

1 ... Laser processing device, 8 ... Light source unit, 9 ... Control unit, 14 ... Condensing unit, 17 ... Detection unit, 34 ... Reflective spatial light modulator, 100 ... Object, 100a ... Front surface, 100b ... Back surface, 111 … GUI.

Claims (8)

A laser processing device that forms a modified region on an object by irradiating the object with laser light.
The light source that emits the laser beam and
A spatial light modulator that modulates the laser beam emitted from the light source, and
A condensing unit that condenses the laser beam modulated by the spatial light modulator on the object, and a condensing unit.
A detection unit that detects the reflected light of the laser beam in the object,
With a control unit,
The control unit
The first process of setting and displaying the first branch pattern in the spatial light modulator according to the output target value of each laser beam after branching, which is a branch pattern in which the laser light is branched into a plurality of pieces,
A second process of controlling the light source so that the laser beam is emitted while the first branch pattern is displayed on the spatial light modulator.
A third process of controlling the detection unit so that the reflected light of each laser beam after branching according to the first branch pattern is detected.
The fourth process of deriving the brightness of the reflected light of each laser beam after the branch based on the detection result by the detection unit, and
Based on the derived luminance, the fifth process of generating a second branch pattern in which the first branch pattern is corrected so that the output of each laser beam after branching becomes the output target value is executed. Laser processing equipment. The control unit
The sixth process of setting and displaying the second branch pattern on the spatial light modulator,
It is configured to further execute the seventh process of controlling the light source so that the laser beam is emitted and the object is processed in the state where the second branch pattern is displayed on the spatial light modulator. The laser processing apparatus according to claim 1. The laser processing apparatus according to claim 1 or 2, wherein the control unit controls the light source so that the laser beam is irradiated at an output at which the modified region is not formed on the object in the second process. It also has an input unit that accepts input from the user.
In the first process, the control unit determines the output target value based on the information received by the input unit, and transfers the first branch pattern according to the determined output target value to the spatial light modulator. The laser processing apparatus according to any one of claims 1 to 3 to be set. The condensing point of the laser light collected by the condensing unit is set on the surface which is the incident surface of the laser light in the object.
The laser processing apparatus according to any one of claims 1 to 4, wherein the detection unit detects the reflected light on the surface. The condensing point of the laser light collected by the condensing unit is set on the back surface, which is the surface opposite to the incident surface of the laser light in the object.
The laser processing apparatus according to any one of claims 1 to 4, wherein the detection unit detects the reflected light on the back surface. In the first process, the control unit sets the output target value of each laser beam after the branch as a common value, and sets and displays the first branch pattern corresponding to the common value in the spatial light modulator. The laser processing apparatus according to any one of claims 1 to 6. A laser processing method for forming a modified region on an object by irradiating the object with a laser beam.
The first step, which is a branching pattern in which the laser beam is branched into a plurality of branches, and the first branching pattern corresponding to the output target value of each laser beam after the branching is set in the spatial light modulator and displayed.
The second step of emitting laser light to the spatial light modulator on which the first branch pattern is displayed and irradiating the object with the laser light branched into a plurality of pieces by the first branch pattern.
The third step of detecting the reflected light of each laser beam after branching from the object, and
A fourth step of deriving the brightness of the reflected light of each laser beam after the branch based on the detection result of the reflected light, and
A laser processing method including a fifth step of generating a second branch pattern in which the first branch pattern is corrected so that the output of each laser beam after branching becomes the output target value based on the derived brightness. ..

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