JP2013022627A - Cleaving method by laser, laser cleaving device and laser beam generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaving method by laser, which can reduce formation of an opaque region at least relative to visible light and infrared light in a cut face of a cut workpiece and can suppress generation of a heat source caused by laser beams on an incidence face of the laser beams for cutting the workpiece, a laser cleaving device and a laser beam generating device.SOLUTION: In the cleaving method by laser beams in one embodiment, a modification region is formed along a cleaving projected line within the workpiece 34 (Step S41), and an optical absorptance increase region is formed within the workpiece 34 by femtosecond laser (Step S42). Before the optical absorptance increase region is returned to its original state, nanosecond laser which is transparent relative to the workpiece 34 is emitted to the workpiece 34 to make the optical absorptance increase region absorb the nanosecond laser, so as to cut the workpiece 34 along the cleaving projected line (Step S43).

Description

  The present invention relates to a cleaving method using a laser, a laser cleaving device, and a laser beam generator, and more specifically, a cleaving method using a laser that cleaves (cuts) a workpiece such as a substrate with a laser beam, a laser cleaving device, and The present invention relates to a laser beam generator.

  Conventionally, in the laser processing method proposed in Patent Document 1, a modified layer is formed by a laser beam inside a workpiece such as a semiconductor material substrate, a piezoelectric material substrate, or a glass substrate, and processing is performed using the modified layer as a starting point. This is a technique for cutting an object. Specifically, a focused point is aligned with the inside of the processing object, and laser light is irradiated to form a planned cutting portion by the modified layer inside the processing object along the cutting target line of the processing object. Next, the processing target object is irradiated with energy that does not melt the surface of the processing target object so that the laser beam having an absorptivity is focused on the surface of the processing target object. As a starting point, a crack reaches the surface of the workpiece and the workpiece is cut.

  Further, in Patent Document 2, the modified layer is formed using a laser beam having high absorbency with respect to the modified layer formed as described above and transmissive with respect to the non-modified layer. A technique for cutting a workpiece is disclosed. Specifically, the cutting origin region is formed inside the workpiece along the planned cutting line of the workpiece by the modified layer formed by aligning the focal point inside the workpiece and irradiating the laser beam. To do. Next, a laser beam that is transparent to the non-modified layer of the workpiece and has a higher absorbency to the modified layer than the non-modified layer is focused on the modified layer. Irradiate, move the condensing point along the planned cutting line, generate a crack starting from the cutting start region, and cause the crack to reach the front and back surfaces of the processing target to cut the processing target.

Japanese Patent Laid-Open No. 2003-88979 JP 2004-268104 A

Cheng-Hsiang Lin et al., “Investigation of femtosecond-nanosecond dual beam ablation of dielectrics”, Optics letters / vol 35, No 14 / July 15 2010

  In the technique disclosed in Patent Document 1, when the surface of the material is irradiated with laser light that is absorptive of the work symmetrical object when cutting the work object starting from the modified layer, FIG. As shown in FIG. 2, the heat source 3 for growing cracks starting from the modified layer 2 inside the workpiece 1 is generated on the surface 1 a of the workpiece 1. In this case, as shown in FIG. 1, the diffusion of heat after laser irradiation of the laser beam having the absorptivity irradiated so as to be condensed on the surface 1 a is caused by the processing object 1 around the laser irradiation point on the surface. It will spread in a hemispherical shape toward the inside. That is, the heating region 3a having the highest temperature is formed near the laser irradiation point, the heating region 3b having a temperature lower than that of the heating region 3a is formed so as to surround the heating region 3a, and the heating region 3b is surrounded so as to surround the heating region 3b. The heating area | region 3c whose temperature is lower than this is formed. In general, when considering the structure of a semiconductor device, it is deposited in a pattern having thin films such as electrodes on the front surface or the back surface, and it is not desirable to thermally damage those thin films. That is, when a member such as an electrode is provided on the surface 1a, at least the member is positioned on the heat source 3 which is a region heated by the laser beam irradiated so as to be condensed on the surface 1a as described above. Is not preferred.

  Therefore, in order to grow a crack starting from the modified layer inside the workpiece by the method of Patent Document 1, it is a street of about 100 μm to 1 mm (cutting margin for cutting, and a thin film is deposited on that portion. It is necessary to increase the width), and the yield is deteriorated.

  Further, in the technique disclosed in Patent Document 2, the laser beam is transmissive to the non-modified layer of the object to be processed, and has a higher absorbency to the modified layer than the non-modified layer. YAG laser (wavelength 1064 nm) is used. Therefore, a cutting start region that absorbs the YAG laser light, in other words, a region that is opaque to near-infrared light is located on the cut surface. That is, when a substrate cut by the technique disclosed in Patent Document 2 is applied to, for example, a device that oscillates near-infrared light from the cut surface of the substrate, the near-infrared light formed at the time of cutting is applied. Oscillation efficiency decreases due to the opaque region. Therefore, it is desired that a region opaque to near-infrared light is not formed on the cut surface as much as possible. Similarly, it is also desired that a region opaque to visible light is not formed on the cut surface as much as possible.

  In addition, the fact that an opaque region is formed when the modified layer is formed means that the composition ratio of the material is greatly changed by laser irradiation, which is not desirable depending on the application. For example, in sapphire used for LEDs, it is known that if heat damage is caused during the formation of the modified layer, the light extraction efficiency is deteriorated due to a decrease in light transmittance, and the modified layer does not decrease the light transmittance. Is desirable (eg, diamond scribe).

  In addition, light transmittance is not a problem in SiC and GaN, which are new semiconductors used in power devices, etc., but the insulating layer is deteriorated or melted due to precipitation of Si or Ga by forming a modified layer due to thermal damage. Since it is conceivable that the die strength (bending strength) is lowered due to the formation of the region, it is not desirable to form a modified layer due to thermal damage that reduces the light transmittance.

  Therefore, depending on the application, it is desirable to produce a modified layer that does not deteriorate the light transmittance in a predetermined wavelength band (for example, visible light band or near infrared light band). Method 2 is not effective.

  The present invention has been made in view of such problems, and its object is to form a region that is opaque to at least visible light and near infrared light on the cut surface of the cut workpiece. Laser cleaving method, laser cleaving apparatus, and laser light generating apparatus capable of suppressing generation of a heat source caused by the laser light on the laser light incident surface for cutting the workpiece to be cut Is to provide.

  In order to achieve such an object, a first aspect of the present invention is a laser cleaving method, in which a first laser emits visible light and near light along a cleaving line inside a workpiece. A first step of forming a first region that is at least transparent to infrared light and having a refractive index that changes with respect to the workpiece; Inside, the second laser causes the light absorption rate of the second region, which is a region including at least a part of the first region or a region near the first region, to be higher than that in the first step. A second step of temporarily increasing and a third laser that is transparent to the workpiece before the light absorption rate of the second region in which the light absorption rate has temporarily increased is restored. Is applied to the second region where the light absorption rate is temporarily increased. By absorbing the serial third laser, and having a third step of cutting the workpiece along the expected splitting line.

  Moreover, the second aspect of the present invention is a laser cleaving apparatus for cutting a workpiece, wherein the first region is at least transparent to visible light and near-infrared light inside the workpiece. And a first laser for forming a first region whose refractive index is changed with respect to the workpiece, and at least a part of the first region in the workpiece. A second laser for temporarily increasing the light absorptance of the second region which is a region including or in the vicinity of the first region, and is transparent to the workpiece, and A laser beam generator configured to be able to oscillate a third laser absorbed in the second region having a temporarily increased light absorption rate, and the laser beam generator of the laser beam generator Provided on the downstream side of the generated laser, the workpiece A workpiece support unit that has a mountable installation surface and is movable in an in-plane direction of the installation surface and in a normal direction of the installation surface, and the laser beam generator includes the second laser and The third laser delayed for a time within a predetermined time from the pulse of the second laser until the light absorption rate of the second region where the light absorption rate temporarily increased returns to the original space. It is characterized in that it can be emitted in a superimposed manner.

  According to a third aspect of the present invention, there is provided a laser light generating device, which emits a femtosecond laser from a first emission end and can emit a nanosecond laser or a sub-nanosecond laser from a second emission end. And provided at the downstream side of the laser generated from the light source at the second emission end, and gives a predetermined time delay to the nanosecond laser or the sub-nanosecond laser emitted from the second emission end. A delay unit; and a multiplexing unit that combines the femtosecond laser emitted from the first emission end and the nanosecond laser or the sub-nanosecond laser emitted from the delay unit, and the light source includes: An oscillator that oscillates a predetermined laser; a branch coupler that is optically connected to the oscillator; and a first path that optically connects one of the output ends of the branch coupler and the first emission end. And said A first path including first conversion means for converting a constant laser into the femtosecond laser, and the first emission for emitting the femtosecond laser emitted from the first conversion means to the outside. A second path that optically connects the other end, the other output end of the branch coupler, and the second emission end, wherein the predetermined laser is converted into the nanosecond laser or the sub-nanosecond laser. A second path including two conversion means, the second emission end for emitting the nanosecond laser or the sub-nanosecond laser emitted from the second conversion means, and the light source. And a means for switching between the femtosecond laser and the femtosecond laser and the nanosecond laser or sub-nanosecond laser synchronized with each other, and the optical path length of the first path The optical path length of the second path, characterized in that the same.

  Furthermore, a fourth aspect of the present invention is a laser light generator capable of emitting a femtosecond laser and a nanosecond laser or a sub-nanosecond laser from the same emission end, and an oscillator that oscillates a predetermined laser; A branch coupler optically connected to the oscillator; a first path optically connected to one of the output ends of the branch coupler; and a second path optically connected to the other of the output ends of the branch coupler. A second path having conversion means for converting the predetermined laser into a nanosecond laser or a sub-nanosecond laser, and two input ends, and one of the two input ends is the first path A coupling means optically connected to the second path and the other of the two input ends optically connected to the second path, and a laser beam emitted from the multiplexing means of the multiplexing means. Optically connected to the downstream side, The laser emitted from the path through the multiplexing means is converted into a femtosecond laser to be emitted from the laser light generator, and the nanosecond laser emitted from the second path through the multiplexing means Or a means for converting a sub-nanosecond laser into a nanolaser or a sub-nanosecond laser to be emitted from the laser light generator, and the optical path length of the second path passes through the second path from the branch coupler The laser that reaches the multiplexing means is longer than the optical path length of the first path so as to be delayed by a predetermined time from the laser that passes through the first path from the branch coupler and reaches the multiplexing means. It is characterized by that.

  According to the present invention, formation of a region opaque to at least visible light and near-infrared light on the cut surface of the cut workpiece can be reduced, and incidence of laser light for cutting the workpiece is cut. On the surface, it is possible to suppress the generation of a heat source due to the laser beam.

It is a figure which shows a mode that the heat source for cut | disconnecting the process target object from the modified layer as the starting point is formed in the surface of the process target object. It is a schematic diagram of the laser cleaving apparatus based on one Embodiment of this invention. It is a figure which shows the structure of the light source which oscillates the laser based on one Embodiment of this invention. It is a figure which shows the procedure of the cleaving method by the laser of the workpiece based on one Embodiment of this invention. (A) is a figure which shows a mode that a modified area | region is formed in the inside of the workpiece based on one Embodiment of this invention, (b) is an AA arrow directional cross section of (a). It is explanatory drawing demonstrated. It is a figure which shows a mode that the light absorption rate increase area | region is formed inside the process target object based on one Embodiment of this invention. It is a figure for demonstrating reduction of the heat damage to the surface of the workpiece target based on one Embodiment of this invention. It is explanatory drawing explaining the formation state of the modification area | region based on one Embodiment of this invention. It is explanatory drawing explaining the formation state of the modification area | region based on one Embodiment of this invention. It is a figure which shows the structure of the light source which oscillates the laser which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

  In one embodiment of the present invention, in order to form a cutting start point (a place where cutting starts) inside a workpiece (for example, a substrate), the first laser is focused inside the workpiece. A plurality of modified regions are formed along the planned cutting line inside the workpiece. At this time, the modified region may be formed continuously along the planned cutting line, or may be formed intermittently. Next, a region having a light absorption rate higher than the light absorption rate in a region other than the modified region of the workpiece (non-modified region) (hereinafter referred to as “light absorption rate increasing region”). ) Temporarily, the second laser is applied under conditions such that multiphoton absorption occurs but melting does not occur, and an area including at least a part of the modified area inside the workpiece, Or it concentrates on the area | region of the vicinity, and forms the said optical absorptance increase area | region in multiple numbers along the said cutting line. The light absorption rate increasing region may be formed continuously along the planned cutting line or may be formed intermittently. Next, in the light absorption rate increasing region, in order to generate thermal expansion that starts cutting from the starting point portion, it is transparent to the non-modified region and is absorbed in the light absorption rate increasing region. The third laser is irradiated to the workpiece, the third laser is absorbed in the light absorption increase region, the light absorption increase region is heated, and the thermal expansion generated by the heating causes the above Cut the workpiece along the planned cutting line.

  Thus, in one embodiment of the present invention, a modified region that is transparent to at least visible light and near-infrared light is formed inside the workpiece by the first laser, and further, the second laser By forming a light absorption rate increasing region where the light absorption rate is temporarily increased by the step, the third laser is incident on the workpiece while the light absorption rate increasing region continues. Thus, the inside of the processing object can be locally heated, and the processing object is cut from the modified region as a starting point by the local heating. Therefore, it can suppress that the heat source formed with a laser beam generate | occur | produces in the incident surface of the laser beam of a workpiece. Further, since the cut surface of the cut workpiece and / or the region located in the vicinity of the cut surface is transparent to at least visible light and near infrared light, at least visible light and The formation of an opaque region with respect to near-infrared light can be reduced. Furthermore, even when the first laser for forming the modified region is irradiated, the formation of the opaque region can be reduced, so that the change in the composition ratio can be reduced on the cut surface.

  In the present invention, the light absorption rate temporarily increases and the predetermined laser beam is absorbed. However, the light absorption rate increasing region where the light absorption rate returns to the original state after a predetermined time has passed is set inside the workpiece. It is one of the essence to form. That is, it is important to cause the thermal deformation (for example, thermal expansion) by the third laser in the light absorption rate increasing region to act on the modified region and to cut the workpiece from the modified region. Therefore, as long as the above-described thermal deformation can act on cutting starting from the modified region, at least a part of the light absorption rate increasing region may overlap with at least a part of the modified region, or the light absorption rate increase. The region and the modified region may be formed apart from each other.

  In the present invention, the “modified region” is a region that is at least transparent with respect to visible light and near-infrared light, and whose refractive index changes with respect to the periphery of the modified region (non-modified region). It is. The modified region is preferably not a region formed by melting, but a region in which almost no composition change occurs with respect to the non-modified region. One of the requirements for the modified region of this embodiment is that it is transparent to at least visible light and near infrared light. The composition may be changed from the original composition (composition of the non-modified region) as long as it is a composition that transmits at least.

  For example, the modified region according to an embodiment of the present invention may include a crack formed in the workpiece by the first laser. In this case, since the refractive index of the region around the crack is changed with respect to the non-modified region, the region including such a crack and having a changed refractive index becomes the modified region. Further, in one embodiment of the present invention, the modified region may contain cracks that do not become microscopic cavities such as cracks. Also in this case, since the refractive index of the crack and its peripheral part is changed with respect to the non-modified region, the region including the crack and having the changed refractive index becomes the modified region.

  Further, in the present invention, the “light absorption rate increasing region” is a region that is temporarily formed by irradiating the second laser beam under a predetermined condition, and is a second laser having the predetermined condition. This is a region where the absorptance with respect to the third laser light is temporarily increased for a predetermined time (predetermined period) after the light irradiation. Therefore, the light absorption rate increasing region returns to the original state after the predetermined time.

When attention is paid to a certain region to be a light absorption rate increasing region in the workpiece, when the second laser irradiation is irradiated to the certain region, the light absorption rate for the third laser beam is high during the predetermined time. It becomes the light absorption rate increasing region. After a predetermined time, the original state, that is, the certain area is restored. Therefore, for example, when the certain area is an area included in the modified area, the light absorption rate is temporarily increased by irradiation with the second laser light, and the third laser light is incident on the light absorption rate increase area. By irradiation, the light absorption rate increasing region absorbs the third laser beam and is heated. The heating causes thermal deformation (for example, thermal expansion) in the light absorption rate increasing region, and the thermal deformation causes cutting starting from the modified region. However, after the predetermined time has passed, the light absorption rate increasing region returns to the region included in the modified region, that is, the original state. The same can be said even if the above certain region is a non-modified region. Therefore, a certain region that becomes the light absorption rate increasing region is an original region, that is, a modified region, a non-modified region, or a region in which they are mixed, except for a predetermined time after the second laser beam is irradiated. It is. Accordingly, a certain region that becomes the light absorption rate increasing region is at least transparent to visible light and near-infrared light except for a predetermined time after irradiation with the second laser light, and is a non-modified region. The composition ratio does not change or hardly changes.
In the present invention, the “predetermined time” refers to a region where the light absorption rate is increased from when a region inside the workpiece becomes a light absorption rate increase region by the second laser incident under a predetermined condition. It is a period until it returns to the original state from. That is, it is a period in which the formation of the light absorption rate increasing region is continued.

  As can be seen from the above, in one embodiment of the present invention, a modified region that is at least transparent to visible light and near-infrared light is formed by the first laser, and a third region is formed by the second laser. A light absorption rate increasing region is formed by temporarily increasing the light absorption rate with respect to the first laser, and the third laser beam is absorbed by the third laser in the light absorption rate increasing region. The inside of the object is locally heated, and the object to be processed is cut starting from the modified region due to the influence of the heating. It is important in the present invention to select lasers that can realize this as the first to third lasers.

  In one embodiment of the present invention, it is preferable to use an ultrashort pulse laser as the first laser and the second laser, and it is more preferable to use a femtosecond laser. When femtosecond lasers are used as the first laser and the second laser, the pulse width is preferably 30 ps or less, more preferably 20 ps or less, and further preferably 10 fs or more and 20 ps or less. .

  By using a femtosecond laser as the first laser, it is at least transparent with respect to visible light and near-infrared light inside the workpiece, and in a region where the composition ratio is almost the same as that of the unmodified region. Thus, it is possible to form a region including a crack starting point such as a crack or a crack, that is, a modified region of the present invention. In the present invention, the first laser beam is an ultrashort pulse laser that does not melt the laser focal point and its peripheral part by heat, such as the femtosecond laser as described above, that is, the modified region of the present invention is processed. Any laser may be used as long as it is an ultrashort pulse laser that can be formed in an object.

  Further, by using a femtosecond laser as the second laser, the light absorption rate with respect to the third laser (for example, a nanosecond laser or a sub-nanosecond laser) is higher than that in the non-modified region inside the workpiece. A region (light absorption rate increasing region) can be temporarily formed. In the present invention, as the second laser light, multiphoton absorption such as the above-described femtosecond laser occurs, but a part of the workpiece is processed under such a condition that the laser focus and its peripheral part are not melted by heat. Any laser may be used as long as it is an ultrashort pulse laser capable of making the light absorption rate increasing region of the present invention.

  Furthermore, in one embodiment of the present invention, it is preferable to use a short pulse laser having a wider pulse width than the first and second lasers as the third laser, and a short pulse laser having a pulse width of 100 ps or more and 1 μs or less. It is more preferable to use a short pulse laser of 100 ps or more and 20 ns or less. For example, a nanosecond laser or a sub-nanosecond laser can be used as the third laser. By using a nanosecond laser and a sub-nanosecond laser as the third laser, when the light absorption rate increasing region is formed in the workpiece using the femtosecond laser as the second laser, the light absorption rate increasing region is It can be heated locally. In the present invention, the third laser beam is a laser having a wavelength band that is absorbed in a region where the light absorption rate is increased, such as the nanosecond laser and the sub-nanosecond laser as described above, Any laser may be used as long as the laser is transparent or almost transparent to the region.

  Furthermore, in one embodiment of the present invention, examples of the processing object include GaN, SiC, sapphire, and the like. However, it goes without saying that in one embodiment of the present invention, the material of the workpiece is not limited to these materials. That is, the first laser forms the modified region of the present invention, the second laser forms the light absorptance increasing region, and the third laser absorbs the light absorptance increasing region to cause thermal deformation. Thus, any material can be used as long as it is a material that can be cut starting from the modified region.

(First embodiment)
FIG. 2 is a schematic diagram of the laser cleaving apparatus 20 according to the present embodiment.
The laser cleaving apparatus 20 can emit a femtosecond laser as a first laser and a second laser, and a nanosecond laser as a third laser, respectively, and the second laser and the second laser. A laser beam generator 21 capable of spatially superimposing and emitting a third laser delayed by a predetermined time from the laser pulse. The laser light generator 21 includes a light source 22, a half-wave plate 23, a polarization beam splitter (PBS) 24, a mirror 25, a delay circuit 26, and a half-wave plate 27.

  The light source 22 is configured to be able to oscillate a femtosecond laser and a nanosecond laser, respectively, or to oscillate a femtosecond laser and a nanosecond laser in synchronization. The light source 22 includes a short pulse light source 22a that oscillates a femtosecond laser and a long pulse light source 22b that oscillates a nanosecond laser.

A half-wave plate 23 is provided on the downstream side of the short pulse light source 22 a in the laser traveling direction, and a PBS 24 is provided on the downstream side of the half-wave plate 23. In the present embodiment, the half-wave plate 23 is configured so that the femtosecond laser oscillated from the short pulse light source 22 a is incident on the PBS 24 with P-polarized light. Therefore, the femtosecond laser output from the short pulse light source 22 a becomes P-polarized light by the half-wave plate 23 and passes through the PBS 24 as it is.
In the present specification, the downstream side of the laser traveling direction output from the light source 22 is simply referred to as “backward side”, and the upstream side of the laser traveling direction output from the light source 22 is simply referred to as “upstream side”. I will call it.

  A mirror 25, a delay circuit 26, and a half-wave plate 27 are provided in this order on the downstream side of the long pulse light source 22b. The mirror 25 oscillates from the long pulse light source 22b reflected by the mirror 25. The mirror 25, the delay circuit 26, and the half-wave plate 27 are positioned so that the nanosecond laser is incident on the PBS 24 via the delay circuit 26 and the half-wave plate 27. In the present embodiment, the half-wave plate 27 is configured such that the nanosecond laser oscillated from the long pulse light source 22b is incident on the PBS 24 as S-polarized light. Accordingly, the nanosecond laser incident from the upstream side of the half-wave plate 27 becomes S-polarized light by the half-wave plate 27, is reflected by the PBS 24, and is emitted to the downstream side of the PBS 24.

  In this embodiment, the PBS 24 is provided on the downstream side of each of the short pulse light source 22a and the long pulse light source 22b, and the femtosecond laser oscillated from the short pulse light source 22a and the nanosecond laser oscillated from the long pulse light source 22b. Are emitted from the same direction, and can also function as a means for combining the femtosecond laser oscillated from the short pulse light source 22a and the nanosecond laser oscillated from the long pulse light source 22b.

  In the present embodiment, when the femtosecond laser and the nanosecond laser are oscillated synchronously from the short pulse light source 22a and the long pulse light source 22b, a certain nanosecond laser pulse oscillated from the long pulse light source 22b The delay circuit 26 is configured to enter the PBS 24 after a predetermined time delay from the femtosecond laser pulse oscillated from the long pulse light source 22 a oscillated in synchronization with the laser pulse. Note that the predetermined time is a period (for example, a time within several tens of ns) in which the formation of a light absorption rate increasing region generated when a femtosecond laser is incident on the workpiece as the second laser is continued. Accordingly, if the oscillation of the femtosecond laser from the short pulse light source 22a and the oscillation of the nanosecond laser from the long pulse light source 22b are performed in synchronization, a certain femtosecond laser pulse 28a and the femtosecond laser pulse 28a are synchronized. The oscillated nanosecond laser pulse 28b is emitted from the PBS 24 while being shifted in time by the predetermined time. That is, the nanosecond laser pulse 28b is emitted from the PBS 24 with a delay of the predetermined time from the femtosecond laser pulse 28a.

  On the downstream side of the PBS 24, an output attenuator 29 and a beam diameter adjuster 30 are arranged in this order. Therefore, the output of the single femtosecond laser emitted from the PBS 24, the single nanosecond laser, or the combination of the femtosecond laser and the nanosecond laser is attenuated by the output attenuator 29 as desired. (Energy is adjusted), the beam diameter is adjusted to a desired beam diameter by the beam diameter adjuster 30 and emitted to the downstream side.

On the downstream side of the beam diameter adjuster 30, both the femtosecond laser emitted from the short pulse light source 22a and the nano-light laser emitted from the long pulse light source 22b are reflected and visible light is transmitted. The dichroic filter 31, the lens 32, and the XYZ stage 33 are provided in this order. Accordingly, a single femtosecond laser, a single nanosecond laser, or a combination of a femtosecond laser and a nanosecond laser emitted from the beam diameter adjuster 30 is reflected by the dichroic filter 31, and the lens 32 Then, the light enters the processing object held on the XYZ stage 33.
The X axis and Y axis of the XYZ stage 33 are in the in-plane direction of the installation surface for installing the workpiece of the XYZ stage 33, and the Z axis is the normal direction of the installation surface. The XYZ stage 33 is configured so that the workpiece 34 installed on the installation surface can be moved as desired along the X axis, the Y axis, and the Z axis.
In the present embodiment, the focal point of the visible light collected by the lens 32 and the focal points of the femtosecond laser and the nanosecond laser collected by the lens 32 coincide with each other.

  A CCD camera 35 is provided facing the installation surface of the XYZ stage 33. The CCD camera 35 has a visible light source that oscillates visible light, and the visible light oscillated from the visible light source is incident on the workpiece 34 held on the XYZ stage 33 via the dichroic filter 31. The CCD camera 35, the dichroic filter 31, the lens 32, and the XYZ stage 33 are positioned so that the visible light reflected by the workpiece 34 enters the image pickup device of the CCD camera via the dichroic filter 31. .

  A controller 36 that controls the XYZ stage 33 and the CCD camera 35 is electrically connected to the XYZ stage 33 and the CCD camera 35. The control unit 36 includes a CPU that executes processing operations such as various calculations, control, and discrimination, a ROM that stores various control programs executed by the CPU, data during the CPU processing operations, input data, and the like. RAM, a non-volatile memory such as a flash memory or SRAM, and the like. The control unit 36 also includes a keyboard for inputting predetermined commands or data, an input operation unit 37 including various switches, an input / setting state of the XYZ stage 33, a captured image of the CCD camera 35, and the like. Is connected to a display unit 38 (for example, a display). The control unit 36 may be configured to adjust the attenuation rate of the output attenuator 29.

FIG. 3 is a diagram illustrating a configuration of the light source 22 according to the present embodiment.
In FIG. 3, the short pulse light source 22 a includes an oscillator 201, a pulse thinning device 202, a branching coupler 203, a stretcher 204, a spare amplifier 205, an amplifier 206, a pulse compressor 207, and a shutter 208. On the other hand, the long pulse light source 22 b includes a stretcher 209, a spare amplifier 210, an amplifier 211, and a shutter 212.
The shutter 208 is configured so as not to be destroyed even when irradiated with a femtosecond laser emitted from the pulse compressor 207. Similarly, the shutter 212 is configured so as not to be destroyed even when the nanosecond laser emitted from the amplifier 211 is irradiated.

  In FIG. 3, the downstream side of the oscillator 201 that oscillates laser light of 50 MHz and 100 fs is connected to a pulse thinning device 202 via an optical fiber, and the pulse thinning device 202 is connected to the 50 MHz, A 100 fs laser beam is converted to a 500 kHz, 100 fs laser beam and emitted to the downstream side. On the downstream side of the pulse thinning-out device 202, a branch coupler 203, which is a 3 dB coupler, is connected via an optical fiber, and a stretcher 204 is connected to one of the output ends of the branch coupler 203 via an optical fiber. The stretcher 209 is connected to the other via an optical fiber.

  The stretcher 204 converts the laser light of 500 kHz and 100 fs emitted from one output end of the branch coupler 203 into the laser light of 500 kHz and 100 ps and emits it to the downstream side. The upstream side of the stretcher 204 is connected to an auxiliary amplifier 205 via an optical fiber, and the downstream side of the auxiliary amplifier 205 is connected to an amplifier 206 via an optical fiber. On the flow side, a pulse compressor 207 is connected via an optical fiber via an optical fiber. The pulse compressor 207 converts the laser light of 500 kHz and 500 fs emitted from the amplifier 206, and the laser light of 500 kHz and 500 fs is emitted from the emission end 213 of the short pulse light source 22a. In this manner, the short pulse light source 22a can emit a femtosecond laser of 500 kHz and 500 fs. At this time, since the shutter 208 that can move in the arrow direction P is provided on the downstream side of the pulse compressor 207, the short pulse light source 22a turns on the femtosecond laser oscillation by opening and closing the shutter 208, Can be turned off.

  Thus, in this embodiment, each component included in the first path that optically connects one output end of the branch coupler 203 and the output end 213 is emitted from one output end of the branch coupler 203. When the laser passes, the laser is converted into a femtosecond laser to be emitted.

  On the other hand, the stretcher 209 converts the 500 kHz, 100 fs laser beam emitted from the other output end of the branch coupler 203 into a 500 kHz, 1 ns laser beam, and emits it to the downstream side. A backup amplifier 210 is connected to the downstream side of the stretcher 209 via an optical fiber, and an amplifier 211 is connected to the downstream side of the backup amplifier 210 via an optical fiber. The laser light of 500 kHz and 1 nm emitted from the amplifier 211 is emitted from the emission end 214 of the long pulse light source 22b. Accordingly, the long pulse light source 22b can emit a nanosecond laser of 500 kHz and 1 ns. At this time, since the shutter 212 movable in the arrow direction P is provided on the downstream side of the amplifier 211, the short pulse light source 22b turns on / off the oscillation of the nanosecond laser by opening / closing the shutter 212. be able to.

  Thus, in this embodiment, each component included in the second path that optically connects the other output end of the branch coupler 203 and the output end 214 is emitted from the other output end of the branch coupler 203. When the laser passes, the laser is converted into a nanosecond laser to be emitted.

  In the present embodiment, the optical path length of the first path through which the laser light emitted from one output end of the branch coupler 203 passes to the output end 213 of the short pulse light source 22a and the other output end of the branch coupler 203 are emitted. The optical path length of the second path through which the laser beam thus transmitted passes to the emission end 214 of the long pulse light source 22b is set to be the same. Therefore, a single laser beam emitted from a single oscillator 201 can be branched and oscillated as a femtosecond laser and a nanosecond laser synchronized with each other. The adjustment of the optical path length may be performed, for example, by appropriately changing at least one of the length and refractive index of the optical fiber provided between the constituent elements.

  In the present embodiment, since the short pulse light source 22a and the long pulse light source 22b include the shutters 208 and 212, respectively, the light source 22 can be a single femtosecond laser and a nano light by combination of opening and closing of the shutters 208 and 212. A single second laser can be emitted, and a femtosecond laser and a nanosecond laser synchronized with the femtosecond laser can be emitted simultaneously. The control unit 36 may perform opening / closing control of the shutters 208 and 212.

  In the present embodiment, the standby amplifiers 205 and 210 may have a switch function for turning on and off the incident laser light. In this case, since the auxiliary amplifiers 205 and 210 can block the light incident from the upstream side, the laser light emitted from the light source 22 is controlled by controlling the on / off of the auxiliary amplifiers 205 and 210. Can be selected. For example, if both the standby amplifiers 205 and 210 are turned on, the femtosecond laser and the nanosecond laser synchronized with each other are emitted from the light source 22, the standby amplifier 205 is turned on, and the standby amplifier 210 is turned off. The light source 22 emits only a femtosecond laser. Similarly, when the standby amplifier 205 is turned off and the standby amplifier 210 is turned on, the light source 22 emits only a nanosecond laser.

  Further, the branch coupler 203 may be a branch coupler having a branch ratio variable function. In this case, when emitting a femtosecond laser and a nanosecond laser synchronized with each other, the branching ratio between one emission end of the branch coupler 203 and the other emission end is set to 50:50, and only the femtosecond laser is desired to be emitted. In this case, the branching ratio is set to 100: 0, and when only a nanosecond laser is desired to be emitted, the branching ratio may be set to 0: 100.

  With such a configuration, the laser light generator including the short pulse light source 22a, the long pulse light source 22b, the half-wave plate 23, the PBS 24, the mirror 25, the delay circuit 26, and the half-wave plate 27 includes The third laser can be oscillated alone, and the second and third lasers can be oscillated in a temporally and spatially superimposed manner.

Next, an example of a method for setting the focal point of a predetermined laser beam at a predetermined position inside the object to be processed will be described.
When the focal point focused by the lens 32 is set on the surface of the processing target 34, the control unit 36 sets the XYZ stage 33 on which the processing target 34 is set to Z while irradiating the visible light from the CCD camera 35. While moving in the axial direction, the XYZ stage 33 and the CCD camera 35 are controlled so that the CCD camera 35 acquires image data. The control unit 36 acquires the position of the XYZ stage 33 when the focal point of the visible light lens 32 through the lens 32 coincides with the surface of the workpiece 34 based on each imaging data acquired by the CCD camera 35. Then, this position is stored in the RAM of the control unit 36 as a reference position. Therefore, the control unit 36 holds the position in the Z-axis direction of the XYZ stage 33 corresponding to the case where the focal point collected from the lens 32 coincides with the surface of the workpiece 34 as the reference position. This reference position can be used when the lens 32 is provided at the same position and the thickness of the object to be processed is the same as that measured above.

  When the focal point of the femtosecond laser or nanosecond laser through the lens 32 is set at a predetermined position inside the workpiece 34, the position of the XYZ stage 33 in the Z-axis direction is changed using the reference position. For example, when the user wants to set the focal point at a position of x μm from the surface of the processing object 34, the user inputs x μm as focal length information regarding the distance from the surface of the processing symmetrical object 34 to the focal point by the input operation unit 37. Further, the refractive index of the workpiece 34 is input. The control unit 36 moves the XYZ stage 33 based on the reference position stored in the RAM so that the surface of the workpiece 34 matches the focal point from the lens 32. Next, the control unit 36 calculates the corresponding distance of x μm in the input refractive index based on the focal length information input from the user and the refractive index of the processing target 34, and based on the calculation result, the processing target The XYZ stage 33 is moved downward by a predetermined distance from the reference position (in the Z-axis direction and away from the lens 32) so that the focal position comes to the position of x μm from the surface of the object 34 toward the inside. As a result, the focal points of the femtosecond laser and the nanosecond laser collected from the lens 32 are located at a predetermined location inside the workpiece 34.

Below, the cutting method of the processing target object based on this embodiment is demonstrated.
FIG. 4 is a diagram illustrating a procedure of a cleaving method using a laser of a workpiece according to the present embodiment.
First, in step S41, a femtosecond laser (ultrashort pulse laser; for example, 10 fs-30 ps), which is a first laser, is irradiated (for the laser) so as to have a condensing point inside the transparent workpiece 34. Thus, a modified region is formed inside the workpiece 34. This modified region is formed continuously or intermittently along the planned cutting line that is the line to be cut, and the line is formed at a plurality of depths in the depth direction from the surface of the workpiece 34. You can also. This line of the modified region becomes a starting point for cleaving the work symmetry object. For example, when the processing object 34 is sapphire, the light density at this time is a spot of about 1.5 μm with a NA = 0.65 condenser lens 32 using a laser beam with a time width of 500 fs and a wavelength of 1.04 μm. When focused on the diameter, the energy required for crack formation is approximately> 0.05 μJ. The modified region formed at this time is a region in which the refractive index formed by cracks or residual stress caused by internal stress generated at the time of femtosecond laser irradiation is changed, and is not a so-called melted region. Even if the region modified by the femtosecond laser is irradiated with a laser having an energy density that does not cause multiphoton absorption, the modified region does not absorb the laser beam and no further change occurs.

  In FIG. 5A, reference numeral 51 denotes a planned cutting line, and the workpiece 34 is cut along the planned cutting line 51. In the present specification, the planned cutting line may be a virtual line or a line actually written on the surface of the workpiece 34.

  In the present embodiment, when the user inputs the depth (the distance from the surface of the workpiece to the inside) and the refractive index of the workpiece 34 by the input operation unit 37, the control is performed. The unit 36 moves the XYZ stage 33 based on the reference position stored in the RAM and the user input, and moves the XYZ stage 33 so that the focal point of the lens 32 is positioned at a predetermined position inside the workpiece 34. Control. At the same time, the control unit 36 controls the shutters 208 and 212 to open the shutter 208 and close the shutter 212. Accordingly, at this time, only the femtosecond laser is emitted from the light source 22. Next, the control unit 36 moves the YXZ stage 33 so that the laser is scanned along the planned cutting line 51, so that the cutting is scheduled inside the workpiece 34 as shown in FIG. A modified region 52 along the line can be formed. In the present embodiment, the modified region 52 includes a crack. If the shutter 208 is kept open during the laser scanning, the line of the modified region 52 is continuously formed along the planned cutting line. On the other hand, if the shutter 208 is intermittently opened and closed during the laser scanning, the line of the modified region 52 is intermittently formed along the planned cutting line.

  In step S42, a second laser having sufficient energy to generate a solid internal plasma to form a light absorption increase region in or near the line of the modified region 52 formed in step S41. A femtosecond laser (ultrashort pulse laser; for example, 10 fs-30 ps) is irradiated. At this time, the energy density of the second laser does not necessarily need to have an energy enough to modify the material (energy enough to form a modified region), but an energy that induces solid internal plasma or a photoionization phenomenon. If there is. For example, when using a laser beam having a time width of 500 fs and a wavelength of 1.04 μm and condensing to a spot diameter of about 1.5 μm by the condenser lens 32 with NA = 0.65, it is about> 0.01 μJ. At this time, the light absorption rate of the transparent material is temporarily increased by solid internal plasma or self-absorption of photoionization (avalanche absorption). Since the internal plasma or photoionization occurs only in the region where the photon density is high, the purpose of step S42 is to form a portion having a high light absorption rate locally with respect to the transparent material. It is described in Non-Patent Document 1 that the duration of the increase in absorption rate by this plasma or photoionization is about ˜30 ns (at the time of laser irradiation of fused silica, 120 fs, 800 nm).

  In the present embodiment, when the user inputs the depth at which the light absorption rate increasing region should be formed by the input operation unit 37, the control unit 36, based on the reference position stored in the RAM and the user input, The XYZ stage 33 is moved, and the XYZ stage 33 is controlled so that the focal point of the lens 32 is positioned at a predetermined position inside the workpiece 34. For example, when the user inputs a depth at which the light absorption rate increasing region is formed at a position shallower than the modified region 52, the control unit 36 causes the focal point from the lens 32 to be larger than when the modified region 52 is formed. The XYZ stage 33 is controlled so as to be located in a shallow region. Next, the control unit 36 causes the femtosecond laser oscillated from the short pulse light source 22a to attenuate the laser output to such an energy that multi-photon absorption occurs but the laser focal point and its peripheral part are not melted by heat. Then, the output attenuator 29 is controlled, and the YXZ stage 33 is moved so that the laser is scanned along the planned cutting line 51. As a result, as shown in FIG. 6, the light absorption rate increasing region 53 is formed along the planned cutting line 51 immediately above the modified region 52. If the shutter 208 is kept open during the laser scanning, the line of the light absorption rate increasing region 53 is continuously formed along the planned cutting line. On the other hand, if the shutter 208 is opened and closed intermittently during the laser scanning, the line of the light absorption rate increasing region 53 is intermittently formed along the planned cutting line.

  In step S43, the nanosecond laser as the third laser is obtained before the light absorption rate of the absorption region returns to the original with respect to the absorption region (light absorption rate increasing region 53) locally formed in step S42. Is made incident on the light absorption increasing region. Note that the third laser preferably overlaps the second laser spatially and / or temporally. By irradiating a nanosecond laser (laser transparent to the workpiece) that is the third laser, the third laser is not absorbed on the surface of the material, but is excited in step S42 (light absorption rate). It is absorbed only in the increased region), and the inside of the workpiece 34 can be locally heated. As a result, an extreme temperature gradient can be created near the planned cutting line 51 inside the workpiece 34. At this time, the energy of the third laser is adjusted to an energy that gives thermal expansion to the material but does not generate a melting region. Step S43 and step S42 need to be performed simultaneously in time or within 10 ns from step S42. It is desirable that the time width of the third laser be able to efficiently apply heat to the material and that the light irradiation continues until electron excitation → lattice vibration → thermal diffusion proceeds by light. The laser duration is preferably> 100 ps or more.

  In this step, under the control of the control unit 36, the shutter 212 is opened while the shutter 208 is open. Thereby, the femtosecond laser and the nanosecond laser synchronized with the femtosecond laser are simultaneously oscillated from the light source 22. Since the delay circuit 26 is provided between the long pulse light source 22b and the PBS 24, the femtosecond laser (second laser) emitted from the PBS 24 in synchronization with the light source 22 is only for the predetermined time. A delayed nanosecond laser (third laser) can be emitted. Therefore, a femtosecond laser as a second laser is incident on a predetermined region inside the workpiece 34 to form a light absorption rate increasing region 53, and the light absorption rate increasing region before the predetermined time elapses. A nanosecond laser as a third laser is incident on 53. Therefore, the light absorption rate increasing region 53 absorbs the nanosecond laser, and the light absorption rate increasing region 53 is heated. As a result, an extreme temperature gradient is generated between the light absorption rate increasing region 53 and the crack included in the modified region 52. That is, the light absorptance increasing region 53 is thermally expanded, and a stress that expands the crack portion due to the thermal expansion acts on the crack, and the stress causes cutting starting from the crack. As a result, the workpiece 34 is cut along the planned cutting line 51.

  By the above steps, an extreme temperature gradient can be generated only in the vicinity of the modified region 52 formed in step S41, and the material can be cut starting from the modified region 52 including cracks and the like formed in step S41. . Therefore, the conventional two-stage process of forming a modified layer by femtosecond laser and a break by external mechanical stress is not required for cutting the material, and cutting by only laser irradiation is possible.

  Further, in the present embodiment, the light absorption rate increasing region 53 in which thermal deformation that causes laser beam absorption and cutting starting from the modified region occurs returns to the original state after a predetermined time has elapsed. The original state is a non-modified region, a modified region, or a region in which it is mixed, but in any case, it is a region that is at least transparent to visible light and near-infrared light. After cutting the object, the generation of at least an opaque region with respect to visible light and near-infrared light can be reduced on the cut surface and inside of the cut workpiece.

  In the present embodiment, the first to third lasers are not a single beam but can be a multi-beam (using DOE or the like) having three focal points in the depth direction, for example.

  Further, depending on the ease of cracking of the material to be processed, step S41 can be omitted by adjusting the energy of the second laser (ultra-short pulse laser) in step S42 to an energy that allows the modified region. Also good.

As described above, according to the present embodiment, the second laser irradiation can locally form a light absorption region (light absorption rate increasing region) inside the workpiece and heat only that portion. The heat source 71 formed by these lasers is inside. Therefore, as shown in FIG. 7, when a predetermined deposited thin film 72 is formed on the surface of the workpiece 34 by thermal diffusion, the deposited thin film 72 is not thermally damaged, or the deposited thin film 72 is moved to. Can reduce the heat damage. In FIG. 7, reference numeral 71a is a heating area having the highest temperature near the laser irradiation point, and reference numeral 71b is a heating area having a lower temperature than the heating area 71a formed so as to surround the heating area 71a. 71c is a heating area | region where temperature is lower than the heating area | region 71b formed so that the heating area | region 71b might be enclosed.
In the method of Patent Document 1, the position of the heat source is limited to the surface, and the distance from the modified layer to the heat source becomes long depending on the case, so the effect is weak. On the other hand, in this embodiment, since a thermal gradient can be created in the immediate vicinity of the modified region, the stress applied by the thermal gradient can be increased.
In the method of Patent Document 2, it is necessary that the modified layer has a constant light absorption property. However, in this embodiment, the light absorption rate temporarily increases and the light absorption rate returns to the original state after a predetermined time has elapsed. Since the region is formed, the material can be cut without significantly changing the composition of the material. That is, since the region for generating the heat source 71 is formed by the second laser, a third region that contributes to the heat for cutting temporarily in a certain region in the workpiece only during cutting. The region can absorb laser light, and the other region can be a region that is at least transparent to visible light and near infrared light.

(Second Embodiment)
In the first embodiment, the formation region of the modified region is set to one in the depth direction (Z-axis direction) of the workpiece, but as shown in FIG. Alternatively, the workpiece 34 may be continuously formed from the front surface (surface on the lens 32 side) 81 toward the back surface (surface on the installation surface side of the XYZ stage 33) 82. In FIG. 8, reference numeral 84 denotes a light absorption rate increasing region, and reference numeral 85 denotes a region heated by irradiation with the third laser.

  In this case, when the focal point of the visible light lens 32 through the lens 32 coincides with the back surface 82 of the workpiece 34, the control unit 36 uses the CCD camera 35 to detect the surface of the workpiece 34. The position (back surface position) of the XYZ stage 33 is acquired. Next, the control unit 36 moves the XYZ stage 33 to the back surface position so that the focal point through the lens 32 coincides with the back surface 82, and lowers the XYZ stage 33 at a predetermined speed from this state (from the front surface 81 to the back surface). And a femtosecond laser is incident on the workpiece 34 together with this.

  When the XYZ stage 33 is lowered by the thickness of the workpiece 34, the control unit 36 determines that the focal point through the lens 32 coincides with the surface 81, and follows the planned cutting line on the XY axis. The XYZ stage 33 is moved by a predetermined distance, and the XYZ stage 33 is moved so as to be the back surface position. Next, in the same manner as described above, femtosecond laser is continuously scanned from the back surface 82 toward the front surface 81 to form the modified region 83 continuously from the back surface 82 toward the front surface 81.

Further, as shown in FIG. 9, the modified region 91 may be formed intermittently from the front surface 81 to the back surface of the workpiece 34.
In this case, the control unit 36 may be configured so that the shutter 208 is opened and closed intermittently when the workpiece 34 is irradiated with the femtosecond laser while the XYZ stage 33 positioned at the back surface is moved downward. .

(Third embodiment)
In the present embodiment, in the configuration shown in FIG. 2, the laser light generator provided on the upstream side of the output attenuator 29 includes a light source 100 that emits a femtosecond laser and a nanosecond laser from the same emission end. .
In FIG. 10, the downstream side of the oscillator 301 that oscillates laser light of 50 MHz and 100 fs is connected with a pulse thinning-out device 302 via an optical fiber. A 100 fs laser beam is converted to a 500 kHz, 100 fs laser beam and emitted to the downstream side. On the downstream side of the pulse decimation device 302, a branch coupler 303, which is a 3 dB coupler, is connected via an optical fiber, and a stretcher 304 is connected to one of the output ends of the branch coupler 303 via an optical fiber. A stretcher 307 is connected to the other via an optical fiber.

  The stretcher 304 converts the 500 kHz, 100 fs laser beam emitted from one output end of the branch coupler 303 into a 500 kHz, 100 ps laser beam, and emits it to the downstream side. A standby amplifier 305 having a function of turning on and off incident light is connected to the downstream side of the stretcher 304 via an optical fiber. The control unit 36 may switch the standby amplifier 305 on and off. On the downstream side of the standby amplifier 305, an amplifier 306 is connected via an optical fiber. The amplifier 306 has two inputs, and one input is connected to the spare amplifier 305.

  On the other hand, the stretcher 307 converts the 500 kHz, 100 fs laser light emitted from the other output end of the branch coupler 303 into a 500 kHz, 1.1 ns laser light, and emits it to the downstream side. A standby amplifier 308 having a function of turning on and off incident light is connected to the downstream side of the stretcher 307 via an optical fiber. The control unit 36 may switch the standby amplifier 308 on and off. On the downstream side of the standby amplifier 308, the other input terminal of the amplifier 306 is connected via an optical fiber.

  As described above, since the amplifier 306 has two input terminals in the present embodiment, the amplifier 306 also functions as a multiplexing unit that combines the light branched by the branch coupler 303. Therefore, the amplifier 306 generates a 500 kHz, 100 ps laser beam that is the source of the femtosecond laser to be oscillated from the light source 300, and a 500 kHz, 1.1 ns laser beam that is the source of the nanosecond laser to be oscillated from the light source 300. Amplified and output to the downstream side.

  On the downstream side of the amplifier 306, a pulse compressor 309 is connected via an optical fiber via an optical fiber. The pulse compressor 309 is configured to correct chirp for 100 ps. Thus, a 100 ps pulse incident on the pulse compressor 309 is compressed to femtoseconds, whereas a 1.1 ns pulse is only compressed to 1 ns. Therefore, the pulse compressor 309 converts the 500 kHz, 100 ps laser light emitted from the amplifier 306 into a 500 kHz, 500 fs femtosecond laser and emits it, and the 500 kHz, 1.1 ns laser light emitted from the amplifier 306 is emitted. It is converted into a 500-second, 1-ns nanosecond laser and emitted.

  In the present embodiment, the laser light emitted from the single oscillator 301 is branched and combined into the first and second paths. However, in the first path, the laser light from the oscillator 301 is light source 300. In the second path, the laser light from the oscillator 301 is converted into the laser that is the source of the nanosecond laser that is to be emitted from the light source 300. The first path for converting the laser light emitted from the oscillator 301 into a femtosecond laser is to connect the optical fiber 310 that connects the branch coupler 303 and the stretcher 304, the stretcher 304, the stretcher 304, and the standby amplifier 305. The optical fiber 311 to be connected, the spare amplifier 305, and the optical fiber 312 to connect the spare amplifier 305 and the amplifier 306. The second path for converting the laser light emitted from the oscillator 301 into a nanosecond laser is to connect the optical fiber 313 connecting the branch coupler 303 and the stretcher 307, the stretcher 307, the stretcher 307, and the standby amplifier 308. Optical fiber 314 to be connected, spare amplifier 308, and optical fiber 315 to connect spare amplifier 308 and amplifier 306.

  In the present embodiment, another pulse emitted from the other emission end simultaneously with a certain pulse emitted from one emission end of the branch coupler 303 is delayed by a predetermined time from the above-mentioned pulse, and the amplifier 306 as a multiplexing means. The second path is configured to reach That is, by setting the optical path length of the second path to be longer than the first optical path length so as to reach the amplifier 306 with a predetermined time delay from a certain pulse, the second path A delay circuit function is provided. Note that the optical path length of the second path may be adjusted by adjusting at least one of the length and refractive index of the optical fibers 313, 314, and 315.

  In the present embodiment, the type of laser light emitted from the light source 300 can be determined by a combination of on / off of the auxiliary amplifiers 305 and 308. For example, when only the femtosecond laser is emitted from the light source 300, the auxiliary amplifier 305 is turned on (a state in which laser light can pass), the auxiliary amplifier 308 is turned off (a state in which the laser light is blocked), and the nanosecond is emitted from the light source 300. When only the laser is emitted, the spare amplifier 305 may be turned off and the spare amplifier 308 may be turned on. In addition, when the femtosecond laser and the nanosecond laser are emitted from the light source 300 while being spatially and temporally superimposed, both the spare amplifiers 305 and 308 may be turned on.

  The branch coupler 303 may be a branch coupler having a branch ratio variable function. In this case, when the femtosecond laser and the nanosecond laser are emitted while being spatially and temporally superimposed, the branching ratio between one emission end of the branch coupler 303 and the other emission end is set to 50:50, If it is desired to emit only a femtosecond laser, the branching ratio may be set to 100: 0, and if only a nanosecond laser is desired to be emitted, the branching ratio may be set to 0: 100.

  As described above, in this embodiment, the laser oscillation of only the femtosecond laser as the first and second laser beams and the laser oscillation of only the nanosecond laser as the third laser can be performed singly, In addition, the second laser and the third laser delayed by a predetermined time from the second laser pulse are emitted from the same optical fiber, that is, the second laser and the third laser are spatially and temporally Can be superimposed and emitted.

20 Laser cleaving device 21 Laser light generator 22, 300 Light source 22a Short pulse light source 22b Long pulse light source 23, 27 1/2 wavelength plate 24 PBS
Reference Signs List 25 mirror 26 delay circuit 29 output attenuator 30 beam diameter adjuster 31 dichroic mirror 32 lens 33 XYZ stage 35 CCD camera 36 control unit 37 input operation unit 38 display unit 201, 301 oscillator 202, 302 pulse decimation device 203, 303 branch coupler 204, 209, 304, 307 Stretcher 205, 210, 305, 308 Preliminary amplifier 206, 211, 306 Amplifier 207, 309 Pulse compressor 208, 212 Shutter 213, 214 Output end

Claims (8)

A first region that is at least transparent to visible light and near-infrared light by a first laser along a planned cutting line inside the workpiece, and has a refractive index with respect to the workpiece. A first step of forming a first region where is changed;
Inside the object to be processed, the second laser causes the first laser to change the light absorption rate of a second region that is a region including at least a part of the first region or a region near the first region. A second step that is temporarily higher than in the step;
Before the light absorption rate of the second region where the light absorption rate has temporarily increased returns to the original state, the processing target is irradiated with a third laser transparent to the processing target, And a third step of absorbing the third laser in a second region having a high light absorption rate and cutting the workpiece along the planned cutting line. Laser cleaving method. The first and second lasers are ultrashort pulse lasers;
The third laser is a short pulse laser having a pulse width wider than any of an ultrashort pulse laser which is the first laser and an ultrashort pulse laser which is the second laser. The cleaving method using a laser according to claim 1. The first and second lasers are femtosecond lasers;
The cleaving method using a laser according to claim 1 or 2, wherein the third laser is a nanosecond laser or a sub-nanosecond laser.   4. The cleaving method using a laser according to any one of claims 1 to 3, wherein the second laser and the third laser are overlapped spatially and temporally. The first and second lasers are the same laser,
The laser cutting method according to claim 1, wherein the first step and the second step are performed simultaneously. A laser cleaving device for cutting a workpiece,
A first region that is at least transparent to visible light and near-infrared light and has a refractive index that changes with respect to the processing object is formed inside the processing object. And a light absorption rate of a second region which is a region including at least a part of the first region or a region in the vicinity of the first region inside the workpiece. A second laser for temporarily increasing; and a third laser that is transparent to the object to be processed and is absorbed by the second region in which the light absorption rate is temporarily increased. A laser beam generator configured to be capable of oscillating,
The laser beam generator has an installation surface provided on the downstream side of the laser generated from the laser beam generator, and on which the processing object can be installed, and the in-plane direction of the installation surface and the installation surface A workpiece support portion movable in the normal direction,
The laser light generation device is configured to perform a predetermined time until the light absorption rate of the second region where the light absorption rate temporarily increased from the second laser and the pulse of the second laser returns to the original value. A laser cleaving apparatus, wherein the laser cleaving apparatus is configured so as to be able to emit a laser beam that is spatially overlapped with a third laser delayed by a predetermined time. A light source capable of emitting a femtosecond laser from a first emission end and emitting a nanosecond laser or a sub-nanosecond laser from a second emission end;
A delay unit provided on the downstream side of the laser emitted from the light source at the second emission end, and gives a predetermined time delay to the nanosecond laser or the sub-nanosecond laser emitted from the second emission end. When,
Combining means for combining the femtosecond laser emitted from the first emission end and the nanosecond laser or sub-nanosecond laser emitted from the delay means;
The light source is
An oscillator that oscillates a predetermined laser;
A branch coupler optically connected to the oscillator;
A first path optically connecting one of the output ends of the branch coupler and the first emission end, the first path including first conversion means for converting the predetermined laser into the femtosecond laser; 1 path,
The first emission end for emitting the femtosecond laser emitted from the first conversion means to the outside;
A second path for optically connecting the other output end of the branch coupler and the second output end, wherein the predetermined laser is converted into the nanosecond laser or the sub-nanosecond laser; A second path including means;
The second emission end for emitting the nanosecond laser or sub-nanosecond laser emitted from the second conversion means to the outside;
Means for switching the laser emitted from the light source between the femtosecond laser and the femtosecond laser and the nanosecond laser or sub-nanosecond laser synchronized with each other;
An optical path length of the first path and an optical path length of the second path are the same. A laser light generator capable of emitting a femtosecond laser and a nanosecond laser or a sub-nanosecond laser from the same emission end,
An oscillator that oscillates a predetermined laser;
A branch coupler optically connected to the oscillator;
A first path optically connected to one of the output ends of the branch coupler;
A second path optically connected to the other output terminal of the branch coupler, the second path having conversion means for converting the predetermined laser into a nanosecond laser or a sub-nanosecond laser;
Multiplexing having two input ends, one of the two input ends being optically connected to the first path, and the other of the two input ends being optically connected to the second path Means,
The laser that is optically connected to the downstream side of the laser emitted from the multiplexing means of the multiplexing means and that is emitted from the first path via the multiplexing means is emitted from the laser light generator. Conversion to a femtosecond laser to be emitted, and conversion of a nanosecond laser or subnanosecond laser emitted from the second path through the multiplexing means into a nanolaser or subnanosecond laser to be emitted from the laser light generator And means for
The optical path length of the second path is such that a laser that passes through the second path from the branch coupler and reaches the multiplexing means passes through the first path from the branch coupler and passes through the first path. A laser light generator characterized by being longer than the optical path length of the first path so as to be delayed by a predetermined time from the laser arriving at.

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