TW201334902A - Laser machining method - Google Patents

Abstract

In the present invention, laser light (L) is focused onto a quartz-crystal workpiece (1) such that a modified region (7) containing a plurality of modified spots (S) is formed in the workpiece (1) along a planned-cut line (5). To do so, the workpiece (1) and/or the laser light (L) is moved so as to produce relative movement therebetween along the planned-cut line (5) as the laser light (L) is shined on the workpiece (1), thereby forming a plurality of modified spots (S1) inside the workpiece (1) along the planned-cut line (5). Then, the workpiece (1) and/or the laser light (L) is moved so as to produce relative movement therebetween along the planned-cut line (5) as the laser light (L) is shined on the workpiece (1), thereby forming a plurality of modified spots (S2) exposed at the surface (3) of the workpiece (1) along the planned-cut line (5) such that no cracks exposed to the surface (3) are formed.

Description

Laser processing method

The present invention relates to a laser processing method for cutting an object to be processed.

As a laser processing method of the prior art, it is known that the laser light is collected at the object to be processed, and at the object to be processed, a modified region is formed along the line to be cut, and the planned line is cut. The object to be processed is cut (for example, refer to Patent Document 1). In such a laser processing method, a plurality of modified spots are formed along a line to be cut, and the modified regions are formed by the plurality of modified points.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-108459

Here, in the above-described general laser processing method, when the object to be processed formed of crystal is cut, it is easy to cause, for example, a large crack, and therefore, the crack is controlled. It is not easy to control the dimensional accuracy (processing quality) of the object to be processed after cutting, and it is difficult to increase the dimensional accuracy.

Therefore, an object of the present invention is to provide a laser processing method capable of cutting an object to be processed by crystals with good dimensional accuracy.

In order to solve the above problems, a laser processing method according to one aspect of the present invention is a laser processing method for cutting an object to be processed by a crystal along a line to be cut. A modified region forming process for forming a modified region including a plurality of modified spots at a processing target along a line to be cut by collecting the laser light at the object to be processed, and modifying In the area forming process, the laser beam is irradiated with respect to the object to be processed, and is moved relative to the planned cutting line to form a plurality of positions inside the object to be processed along the line to cut. The first modification point is performed; and the laser beam is irradiated to the object to be processed, and the relative movement is performed along the line to cut along the line to be cut, so that the film is not formed and exposed. The project in which the laser light of the object is incident on the surface is formed to form a plurality of second modified spots exposed on the laser light incident surface of the object to be processed.

When the object to be processed is cut by the laser processing method, it is easily made along the line to cut by the plurality of first modified spots formed inside. The second modified point which is cut off and exposed on the laser light incident surface functions as a so-called pre-cut line which is made by the second modified point of the plural Auxiliary. Therefore, it is possible to make the object to be processed in good condition. Inch accuracy is used to cut off.

In addition, it is possible to further cut off the object to be processed by applying a force to the object to be processed from the outside by cutting the predetermined line, and using the modified region as the starting point of the cutting. . As a result, it is possible to cut the object to be processed reliably along the line to cut.

According to the present invention, it is possible to cut the object to be processed which is formed of crystal with good dimensional accuracy.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent components are designated by the same reference numerals, and the description thereof will not be repeated.

In the laser processing method of the present embodiment, the laser beam is collected by the object to be processed, and a modified region including a plurality of modified spots is formed along the line to cut. Therefore, first, the formation of the modified region will be described with reference to FIGS. 1 to 6 .

As shown in FIG. 1, the laser processing apparatus 100 is generally provided with a laser light source 101 for pulsing laser light L and a 90° change of the direction of the optical axis (optical path) of the laser light L. The dichroic mirror 103 and the collecting lens (collecting optical system) 105 for collecting the laser light L are arranged in such a manner. Further, the laser processing apparatus 100 is provided with a laser light L that is used to illuminate the light collected by the light collecting lens 105. The support table 107 for supporting the object 1 and the platform 111 for moving the support table 107, and for controlling the output of the laser light L or the pulse width, the pulse waveform, etc., are controlled for the laser light source 101. The laser light source control unit 102 and the platform control unit 115 that controls the movement of the stage 111.

In the laser processing apparatus 100, the laser light L emitted from the laser light source 101 is changed by 90 degrees by the direction of the optical axis by the dichroic beam splitter 103, and by the lens for collecting light. 105 collects light inside the object 1 to be placed on the support table 107. At the same time, the stage 111 is moved, and the object 1 is relatively moved along the line to cut 5 with respect to the laser light L. As a result, a modified region along the line to cut 5 is formed at the object 1 to be processed. Further, although the stage 111 is moved in order to relatively move the laser light L, the light collecting lens 105 may be moved or both of them may be moved.

The object to be processed 1 is formed of a crystal, and as shown in FIG. 2, in the object 1 to be processed, a cutting line 5 for cutting the object 1 is cut. The cut line 5 is an imaginary line extending in a straight line. When a modified region is formed inside the object 1 to be processed, as shown in FIG. 3, in a state where the light collecting point (light collecting position) P is brought into the inside of the object 1 as described above, The laser light L is relatively moved along the line to cut 5 (that is, in the direction of the arrow A of FIG. 2). As a result, as shown in FIGS. 4 to 6 , the modified region 7 is formed inside the object 1 along the line to cut 5 . The modified region 7 formed along the line to cut 5 is the cutting start region 8.

In addition, the collection point P refers to a place where the laser light L is used for collecting light. Further, the planned cutting line 5 is not limited to a straight line, but may be curved, or may be a three-dimensional shape in which these are combined, or may be designated as a coordinate. Further, the line to cut 5 is not limited to the imaginary line, and may be a line actually drawn on the surface 3 of the object 1 to be processed. The modified region 7 is formed in a continuous form, and is also formed in a discontinuous manner. Further, the modified region 7 may be in a column shape or a dot shape, that is, the modified region 7 may be formed at least inside the object 1 to be processed. Further, cracks may be formed by using the modified region 7 as a starting point, and the crack and the modified region 7 may be exposed on the outer surface of the object 1 (surface 3, back 21, or Outside surface). Further, the laser light incident surface when the modified region 7 is formed is not limited to the surface 3 of the object 1 but may be the back surface 21 of the object 1.

In addition, the laser light L is transmitted through the object 1 and is particularly absorbed near the light collecting point inside the object 1 to form a modified object at the object 1 Zone 7 (ie internal absorption laser processing). Therefore, since the laser light L is hardly absorbed at the surface 3 of the object 1 to be processed, the surface 3 of the object 1 does not melt. In general, when the surface 3 is melted and removed to form a removal portion (surface absorption type laser processing) such as a hole or a groove, the processing region gradually changes from the surface 3 side toward the back surface. Side advance.

Further, the modified region formed in the present embodiment means a region which is in a state different from the surroundings in terms of density, refractive index, mechanical strength, or other physical properties. The modified region is, for example, a molten processed region (a region which is once solidified once melted, a region in a molten state, and a region in a state in which re-solidification is being performed from melting), any of these) , a fragmentation region, an insulation failure region, a refractive index change region, and the like, and include a region in which such regions are mixed. Further, as the modified region, there is also a region in which the density of the modified region is changed in the material of the object to be processed compared to the density of the non-modified region, or a region in which a lattice defect is formed. (This is also collectively referred to as a high-density transfer area).

Further, the region where the density of the molten processed region, the refractive index change region, and the modified region changes with respect to the density of the non-modified region, and the region where the lattice defect is formed may be further The inside of the area is either a boundary between the modified area and the non-modified area and is covered with cracks (fragmentation, micro-cracking). The crack that is included in the package may be a comprehensive situation covering the modified area, or may be formed only at a part or at a plurality of parts. As the object 1 to be processed, crystal (SiO ₂ ) or a material containing crystal is used.

Further, in the present embodiment, the modified region (formation trace) is formed in plural numbers along the line to cut 5 to form the modified region 7. The modified point refers to the modified part formed by the shot of one pulse of the pulsed laser light (that is, the laser irradiation of one pulse: the lightning shot). The modified region 7 is changed by the set of modified points. As the modification point, a cracking point, a melting point or a refractive index change point, or a mixture of at least one of these may be mentioned.

For this modification point, it is preferable to consider the required cutting accuracy, the flatness of the required cut surface, the thickness of the object to be processed, the kind, the crystal orientation, etc., for the size or occurrence thereof. The length of the crack is properly controlled.

Next, a laser processing apparatus according to the present embodiment will be described.

As shown in FIG. 7, the laser processing apparatus 200 is generally provided with a support table 201 for supporting a plate-shaped object 1 and a laser light source 202 for emitting laser light L, and for the laser beam. The reflective spatial light modulator 203 for correcting the aberration of the laser light L emitted from the light source 202 and the laser light L for correcting the aberration by the reflective spatial light modulator 203 are collected. The collecting optical system 204 inside the object 1 supported by the support table 201 and a control unit (control means) 205 for controlling at least the reflective spatial light modulator 203. The laser processing apparatus 200 forms the modified region 7 including a plurality of modified spots along the line to cut 5 of the object 1 by irradiating the object 1 with the laser light L.

The reflective spatial light modulator 203 is disposed in the housing 231, and the laser light source 202 is disposed at the top plate of the housing 231. Further, the collecting optical system 204 is configured by including a plurality of lenses, and is provided at the bottom plate of the casing 231 via a driving unit 232 including a piezoelectric element or the like. Moreover, the thunder is formed by the parts provided at the frame 231. The engine 230 is fired. Further, the control unit 205 may be provided in the casing 231 of the laser engine 230.

At the housing 231, a moving mechanism (not shown) that moves the housing 231 in the thickness direction of the object 1 is provided. In this way, since the laser engine 230 can be moved up and down in response to the depth of the object 1 to be processed, the position of the collecting optical system 204 can be changed and the laser beam L can be collected on the object 1 At the desired depth position. Further, instead of providing a moving mechanism in the casing 231, a moving mechanism for moving the support table 201 in the thickness direction of the object 1 may be provided at the support table 201. Moreover, the collecting unit optical system 204 can be moved toward the thickness direction of the object 1 by the AF unit 212 which will be described later. Also, these may be combined.

The control unit 205 controls the entire laser processing apparatus 200 in addition to the control of the reflective spatial light modulator 203. For example, when the modified region 7 is formed, the control unit 205 is configured such that the light collecting point P of the laser light L is located at a position away from the surface (the laser light incident surface) 3 of the object 1 and separated by a specific distance. The laser light collecting point P of the laser light L is relatively moved along the line to cut 5, and the laser engine 230 including the collecting optical system 204 is controlled. Further, in order to relatively move the light collecting point P of the laser light L with respect to the object 1 to be processed, the control unit 205 may not control the laser engine 230 including the collecting optical system 204, but may The support table 201 is controlled, or both the laser engine 230 including the collecting optical system 204 and the support table 201 can be controlled.

The laser light L emitted from the laser light source 202 is reflected in the frame 231 by the mirrors 206 and 207, and then reflected by the reflection member 208 such as 稜鏡, and The injection is made to the reflective spatial light modulator 203. The laser light L incident on the reflective spatial light modulator 203 is modulated by the reflective spatial light modulator 203, and is emitted from the reflective spatial light modulator 203. The laser light L emitted from the reflective spatial light modulator 203 is reflected in the casing 231 by the reflecting member 208 along the optical axis of the collecting optical system 204, and sequentially passes through the beam splitter. 209, 210 are injected into the collecting optics 204. The laser light L incident on the collecting optical system 204 is collected by the collecting optical system 204 on the inside of the object 1 placed on the support table 201.

Further, the laser processing apparatus 200 is provided in the casing 231 and has a surface observation unit 211 for observing the surface 3 of the object 1 to be processed. The surface observation unit 211 emits the visible light VL reflected by the beam splitter 209 and transmitted through the beam splitter 210 and is collected by the collecting optical system 204 and reflected by the surface 3 of the object 1 to be processed. The visible light VL is detected to obtain an image of the surface 3 of the object 1 to be processed.

Further, the laser processing apparatus 200 is provided in the casing 231, and is capable of providing the light collecting point P of the laser light L with good precision even when there is undulation at the surface 3 of the object 1 to be processed. The AF (autofocus) unit 212 at a position away from the surface 3 and away from the specific distance is obtained. The AF unit 212 emits the laser light LB for AF reflected by the beam splitter 210 and collects light by the collecting optical system 204 and is processed. The AF reflected by the surface 3 of the object 1 is detected by the laser light LB, and the displacement data along the surface 3 of the line to cut 5 is obtained by, for example, astigmatism. Thereafter, the AF unit 212, when the modified region 7 is formed, is driven by the driving unit 232 based on the acquired displacement data to collect the light along the surface 3 of the object 1 The optical system 204 reciprocates in the optical axis direction thereof to finely adjust the distance between the collecting optical system 204 and the object 1 to be processed.

Here, the reflective spatial light modulator 203 will be described. The reflective spatial light modulator 203 is for correcting the aberration of the laser light L emitted from the laser light source 202, and is, for example, a spatial light modulation using a liquid crystal on silicon (LCOS). (SLM: Spatial Light Modulator). Figure 8 is a partial cross-sectional view showing a reflective spatial light modulator of the laser processing apparatus of Figure 7. As shown in FIG. 8, the reflective spatial light modulator 203 is provided with a germanium substrate 213, a driving circuit layer 914, a plurality of pixel electrodes 214, and a reflective film 215 of a dielectric multilayer mirror or the like. And an alignment film 999a, a liquid crystal layer 216, an alignment film 999b, a transparent conductive film 217, and a transparent substrate 218 such as a glass substrate, and these are laminated in accordance with the above procedure.

The transparent substrate 218 is provided with a surface 218a along the XY plane, which forms the surface of the reflective spatial light modulator 203. The transparent substrate 218 mainly includes a light transmissive material such as glass, and transmits the laser light of a specific wavelength incident from the surface 218a of the reflective spatial light modulator 203 to the reflective spatial light modulation. The inside of the device 203. The transparent conductive film 217 is formed on the back surface of the transparent substrate 218 The 218b is mainly composed of a conductive material (for example, ITO) that transmits the laser light L.

The plurality of pixel electrodes 214 are arranged in a two-dimensional shape in accordance with the arrangement of the plurality of pixels, and are arranged on the ruthenium substrate 213 along the transparent conductive film 217. Each of the pixel electrodes 214 is made of, for example, a metal material such as aluminum, and the surfaces 214a are processed to be smooth. The plurality of pixel electrodes 214 are driven by an active matrix circuit disposed at the driver circuit layer 914.

The active matrix circuit is disposed between the plurality of pixel electrodes 214 and the germanium substrate 213, and controls the voltage applied to each pixel electrode 214 in response to an optical image to be output from the reflective spatial light modulator 203. . Such an active matrix circuit includes, for example, a first driving circuit that controls an applied voltage of each pixel column arranged side by side in the X-axis direction, and a pixel column that is arranged side by side in the Y-axis direction. The second driving circuit that controls the applied voltage is configured such that the control unit 250 applies a specific voltage to the pixel electrode 214 of the designated pixel by both of the driving circuits.

Further, the alignment films 999a and 999b are disposed on both end faces of the liquid crystal layer 216, and the liquid crystal molecules are arranged in a predetermined direction. For the alignment films 999a and 999b, for example, a polymer material such as polyimide or a rubbing treatment is applied to the contact surface with the liquid crystal layer 216.

The liquid crystal layer 216 is disposed between the plurality of pixel electrodes 214 and the transparent conductive film 217, and is adapted to pass through the respective pixel electrodes 214 and the transparent guide The electric field formed by the electric film 217 is used to modulate the laser light L. That is, if a voltage is applied to a certain pixel electrode 214 by an active matrix circuit, an electric field is formed between the transparent conductive film 217 and the pixel electrode 214.

This electric field is applied to each of the reflective film 215 and the liquid crystal layer 216 at a ratio corresponding to the respective thicknesses. Then, in accordance with the magnitude of the electric field applied to the liquid crystal layer 216, the alignment direction of the liquid crystal molecules 216a changes. When the laser light L is transmitted through the transparent substrate 218 and the transparent conductive film 217 and is incident on the liquid crystal layer 216, the laser light L is modulated by the liquid crystal molecules 216a while passing through the liquid crystal layer 216. And reflected at the reflective film 215, and then modulated again by the liquid crystal layer 216, and then taken out. Further, an aberration correction (wavefront shaping) pattern for shaping (modulating) the beam surface of the laser light L is displayed on the liquid crystal layer 216, whereby the aberration correction pattern of the liquid crystal layer 216 is transmitted. The subsequent laser light L is phase-modulated in response to the aberration correction pattern, and the aberration is corrected.

When the modified region 7 is formed, the control unit 205 inputs the pattern information related to the aberration correction pattern to the reflective spatial light modulator 203, and displays a specific aberration correction pattern on the liquid crystal layer 216. Thereby, the aberration of the laser light L emitted from the reflective spatial light modulator 203 is controlled. Further, the pattern information input to the reflective spatial light modulator 203 may be configured to be sequentially input, or may be configured to select and input the previously stored pattern information.

In addition, strictly speaking, by the reflective spatial light modulator 203 The laser light L, which is aberration-corrected, changes the shape of the wavefront due to propagation in space. In particular, the laser light L emitted from the reflective spatial light modulator 203 or the laser light L incident into the collecting optical system 204 is light having a specific expanded diameter (that is, parallel light) In the case of light other than the light, the wavefront shape at the reflective spatial light modulator 203 does not coincide with the wavefront shape at the collecting optical system 204, and as a result, there is a precision for the purpose. Internal processing creates a hindrance. Therefore, it is important to make the wavefront shape at the reflective spatial light modulator 203 and the wavefront shape at the collecting optical system 204 coincide with each other. Therefore, it is more preferable to take out the change in the wavefront shape when the laser light L is propagated from the reflective spatial light modulator 203 to the collecting optical system 204 by measurement or the like, and the wavefront shape is obtained for the wavefront. The pattern information of the aberration correction pattern considered in the change of the shape is input to the reflection type spatial light modulator 203.

Alternatively, in order to make the wavefront shape at the reflective spatial light modulator 203 and the wavefront shape at the collecting optical system 204 coincide with each other, it may also be as shown in FIG. 9 in a reflective spatial light modulation. The adjustment optical system 240 is provided on the optical path of the laser light L that is advanced between the 203 and the collecting optical system 204. By this, it is possible to correctly achieve wavefront shaping.

The adjustment optical system 240 is provided with at least two lenses 241a and 241b. The lenses 241a and 241b are configured to match the wavefront shape at the reflective spatial light modulator 203 with the wavefront shape at the collecting optical system 204. The lenses 241a, 241b are such that the distance between the reflective spatial light modulator 203 and the lens 241a becomes a lens The focal length f1 of 241a is such that the distance between the collecting optical system 204 and the lens 241b becomes the focal length f2 of the lens 241b, and the distance between the lens 241a and the lens 241b becomes f1 + f2, and the lens 241a and the lens 241b are made. The two-way telecentric optical system is disposed between the reflective spatial light modulator 203 and the reflective member 208.

By disposing in this manner, even if the laser light L having a small diffusion angle of about 1° or less is provided, the wavefront at the reflective spatial light modulator 203 can be made at the collecting optical system 204. The wavefronts are consistent with each other. Further, the beam diameter of the laser beam L is determined based on the ratio between f1 and f2 (the beam diameter of the laser beam L incident on the collecting optical system 204 is obtained from the reflection type spatial light modulator 203. F2/f1 times the beam diameter of the emitted laser light L). Therefore, even when the laser light L is parallel light or light having a small diameter expansion, it is possible to maintain the angle from the reflection type spatial light modulator 203. In the state, the desired beam diameter is obtained by entering the laser beam L in the collecting optics 204.

Further, it is preferable to adjust the optical system 240, and it is preferable to provide a mechanism for finely adjusting the positions of the lenses 241a and 241b independently of each other. Moreover, in order to effectively use the effective area of the reflective spatial light modulator 203, a beam expander may be disposed on the optical path of the laser light L between the reflective spatial light modulator 203 and the laser light source 202. .

Next, a laser processing method according to the present embodiment will be described.

The laser processing method according to the embodiment is a user who is a method for manufacturing a crystal resonator element for manufacturing a crystal resonator element, for example, and The object 1 formed by the crystal which is a hexagonal columnar crystal is cut into a plurality of crystal wafers by the laser processing apparatus 200. Therefore, first, a description will be given of a manufacturing process flow of the entire crystal resonator element with reference to FIG.

First, the artificial crystal rough stone is cut out by, for example, diamond grinding, and processed into a rod of a specific size (lumbered) (S1). Next, the cutting angle corresponding to the temperature characteristic requirement of the crystal resonator element is measured by the X-ray, and the wire sawing process is performed on the material based on the cutting angle, thereby cutting the wafer into a plurality of wafers The object to be processed 1 (S2). The object 1 to be processed is a rectangular plate having a size of 10 mm × 10 mm, and has a crystal axis having an inclination of 35.15° with respect to the thickness direction.

Next, friction processing is applied to the front surface 3 and the back surface 21 of the object 1 and the thickness thereof is set to a specific thickness (S3). Then, the cutting angle is measured by the X-ray at a slight angle, and the object 1 is selected and classified. Then, the surface 3 and the back surface 21 of the object 1 are again applied in the same manner as the above S3. In the friction processing, the thickness of the object 1 is finely adjusted to, for example, about 100 μm (S4, S5).

After that, as the cutting process and the outer shape processing, the modified region 7 is formed at the object 1 and the modified region 7 is used as the starting point of the cutting, and the object 1 is cut along the line 5 to be cut. The cutting is performed (S6, the details will be described later). As a result, a crystal wafer having a plurality of outer dimensions having a dimensional accuracy of ±10 μm or less is obtained. In this embodiment In the case of the object 1 to be processed, the cutting line 5 is set in a lattice shape when the surface 3 is observed, and the object 1 is cut as a rectangular plate-shaped crystal wafer of 1 mm × 0.5 mm. .

Next, the crystal wafer is subjected to chamfering (convex processing) so as to have a specific frequency, and the thickness of the crystal wafer is adjusted by etching processing so as to have a specific frequency (S7, S8). Thereafter, the crystal wafer is assembled into a crystal vibration element (S9). Specifically, an electrode is formed on a crystal wafer by sputtering, and the crystal wafer is mounted in a mounter, and heat treatment is performed in a vacuum atmosphere, and then the electrode of the crystal wafer is cut by ion etching. Adjust the frequency and seal the seam in the installer. Thereby, the manufacture of the crystal resonator element is completed.

Fig. 8 is a schematic view for explaining a process of cutting an object to be a crystal wafer. In the drawings, for convenience of explanation, the cutting performed along the one line to cut 5 along one line is exemplified. In the above S6 in which the object 1 is cut into a crystal wafer, first, the expansion tape 31 is attached to the back surface 21 of the object 1 and the object 1 is placed on the support table 201 (refer to FIG. 7). )on.

Then, the control unit 205 controls the laser engine 230 and the reflective spatial light modulator 203, and appropriately collects the laser light L for the object 1 along the line to cut 5 . A modified region 7 (modified region forming project) including a plurality of modified spots S is formed.

Specifically, as shown in FIG. 11( a ), for example, the laser light L is irradiated from the surface 3 side with an output of 0.03 W, a reverse frequency of 15 kHz, and a pulse width of 500 picoseconds to 640 picoseconds. this side so that the laser light L along the line 5 to make relative movement along the line to cut 5 only change to the first plurality of positions inside of the object ₁ as S 1 of the mass of a form (1st scan).

Next, as shown in FIG. 11(b), for example, the laser beam L is irradiated from the surface 3 side with an output of 0.03 W, a repetition frequency of 15 kHz, and a pulse width of 500 picoseconds to 640 picoseconds. The laser beam L is relatively moved along the line to cut 5, and a plurality of second modified spots S ₂ exposed on the surface 3 of the object 1 are formed in a row along the line to cut 5 (second scanning).

Here, it has been found that when the second scanning which is formed on the second modified spot S ₂ which is exposed on the surface 3 of the laser light incident surface is performed, if not only the lightning is simply The incident light L is collected on the surface 3 of the object 1 to be corrected, and the aberration of the laser light L is corrected so that the position of the light collecting point is near the surface 3 in the object 1 The so-called air strike phenomenon (a phenomenon in which the modified spot S is not formed even if the laser light L is collected at the object 1 is suppressed) is suppressed.

Therefore, in the second scanning, the specific aberration for correcting the aberration of the laser light L is such that the spot P of the laser light L is positioned in the vicinity of the surface 3 in the object 1 to be processed. The correction pattern is displayed at the liquid crystal layer 216 of the reflective spatial light modulator 203. At the same time, the focus position of the collecting optical system 204 is at the surface 3 of the object 1 to be processed. In this state, the laser light L is irradiated from the surface 3 side, that is, the side where the light collecting point is located near the surface 3 in the object 1 is placed. The laser light L of the aberration correction is collected at the surface 3 which is the incident surface of the laser light.

In the second scan of the present embodiment, a specific aberration correction pattern in which the light-collecting point position is at a position of 1 μm to 2 μm from the surface 3 of the object 1 is displayed. In the liquid crystal layer 216, the laser beam L having aberration correction is performed so that the position of the light collecting point is within the object 1 from the surface 3 and the position is 1 μm to 2 μm on the inner side. Gather on the surface 3.

As a result, as shown in FIG. 13, it is possible to suppress the occurrence of the so-called air strike phenomenon, and it is possible to form a beautiful edge that does not form a half-cut ground which is exposed to the crack at the surface 3. The cutting planned line 5 is continuously formed to form a plurality of second modified spots S ₂ exposed at the surface 3 (that is, the modified regions 7 which are intermittently exposed from the surface 3).

Then, after the first and second scans are performed on all the planned cutting lines 5, as shown in FIG. 12(a), generally, the object 1 is processed from the back surface 21 side. The blade edge 32 is pressed and attached along the line to cut 5 through the expansion tape 31, and a force is applied to the object 1 from the outside along the line to cut 5 (cutting process).

As a result, the plural first modified point S ₁ functions as a modified point mainly contributing to the cutting, and the second modified point S ₂ is used as an auxiliary for the cutting. The reforming of the surface scratch marks continues to function, and the modified region 7 is used as a starting point for cutting, and the object 1 is cut into a plurality of crystal wafers. Thereafter, as shown in Fig. 12 (b), the expansion tape 31 is expanded to secure the interval of the wafers. By the above-described work, the object 1 is cut into a plurality of crystal wafers 10.

As described above, in the present embodiment, the plurality of first modified spots S ₁ positioned at the inside of the object 1 are formed along the line to cut 5, and the second modified point of the plurality of surfaces 3 is exposed. S ₂ is formed along the line to cut 5 . Therefore, the modified region 1 is easily cut along the line to cut 5 by the plurality of first modified spots S ₁ , and is exposed to the second modified point S _{2 of the} surface 3 . It functions as a so-called pre-cut line which is assisted by the second modified point S _{2 of} the plurality. Therefore, it is possible to cut the object 1 with good dimensional accuracy, and it is possible to improve the processing quality.

In particular, if a half cut occurs in the object 1 formed by the crystal, the half cut is easy to meander because of the processing characteristics of the crystal, for example, and therefore, the object to be processed after cutting It is not easy to control the dimensional accuracy of the object 1. In this regard, in the present embodiment, as described above, since laser processing can be performed so that the half cut is not formed from the second modified spot S ₂ , it is possible to be more accurate in size. The object 1 is cut off.

Further, in the present embodiment, as described above, the blade 32 is used to apply an external stress to the object 1 along the line to cut 5, and the modified region 7 is used as a starting point for cutting. The object 1 is cut off. By this, even the processing pair formed by the crystal that is difficult to cut The object 1 is also capable of reliably cutting the object 1 with good precision along the line to cut 5 .

In addition, when the second modified spot S ₂ exposed on the surface 3 is formed, the aberration correction is performed such that the position of the light collecting spot is less than 1 μm from the surface 3 in the object 1 When the laser light L is collected on the surface 3, and the laser beam is aberration-corrected in such a manner that the position of the light-collecting spot is more than 2 μm from the surface 3 in the object 1 When L is concentrated on the surface 3, a so-called air strike phenomenon is easily generated. Therefore, in such cases, the processing quality is lowered.

Fig. 14 is a photograph showing the surface of the object to be processed in which the second modified point is formed in the comparative example. In the middle of the process, the laser beam L which is aberration-corrected is collected on the surface 3 so that the position of the light-collecting spot is at a position on the inner surface 3 of the object 1 and is 3 to 6 μm inside. The second modification point S ₂ . As shown in Fig. 14, it can be seen that when the second modified spot S ₂ exposed on the surface 3 is formed, the position of the light collecting spot is made deeper than the surface 3, When the aberration-corrected laser light L is collected on the surface 3, a flying strike phenomenon is generated (refer to the in-frame portion in the drawing).

In addition, since the crystal vibrating element is a component that utilizes the characteristics of the material of the crystal itself, the dimensional accuracy of the crystal wafer for the crystal vibrating element has a large influence on the temperature characteristics and the characteristics of the vibrating element. In this regard, the present embodiment, which is capable of cutting the object 1 with good dimensional accuracy as a crystal wafer, is particularly effective. Further, even when the second modified spot S ₂ remains (exposed) on the surface 3, the influence on the temperature characteristics of the crystal wafer and the characteristics of the vibrating element is small. Further, even if the output of the processing point of the laser light L is simply raised, it is difficult to suppress the occurrence of the so-called air-scratch phenomenon, and it is more likely to cause scorch marks or scratches on the surface 3, so not ideal.

The above is a description of the preferred embodiments of the present invention, and the present invention is not limited to the above-described embodiments, and is not intended to change the scope of the claims. It can be arbitrarily deformed or applied to other components.

For example, in the above-described embodiment, the LCOS-SLM is used as the reflective spatial light modulator 203, but MEMS (Micro Electro Mechanical Systems)-SLM or DMD (Deformable Mirror Device) may be used. . The reflective spatial light modulator 203 of the above-described embodiment includes a dielectric multilayer mirror, but it is also possible to reflect by the pixel electrode of the germanium substrate. Further, in the above embodiment, the reflective spatial light modulator 203 is used. However, a transmissive spatial light modulator may be used. Examples of the spatial light modulator include a liquid crystal cell form and an LCD form.

Further, in the above-described embodiment, the laser light L is corrected in a state where the aberration of the laser light L is corrected so that the light collecting point is located in the vicinity of the surface 3 of the object 1 to be processed. The second modified point S ₂ is formed on the surface 3, but is not limited thereto, as long as the second modified spot exposed at the laser light incident surface can be formed so as not to cause half cut. The way to form it is fine. For example, the second modification point S ₂ may be formed by appropriately controlling the laser processing apparatus 200 by the control unit 205.

Further, in the above embodiment, the second modified spot S _{2 is} formed after the first modified spot S ₁ is formed. However, after the second modified spot S _{2 is} formed, the first modified spot S _{2 may} be formed. Change point S ₁ . When the modified region 7 of the plurality of columns in which the positions in the thickness direction are different from each other is formed at the object 1 to be processed, the order of formation of the modified regions 7 is different.

In the above description, the numerical values relating to the aberration correction are allowed for errors in processing, manufacturing, design, and the like. Further, the present invention can be regarded as a method of manufacturing a crystal resonator element or a manufacturing apparatus for manufacturing a crystal resonator element by the above-described laser processing method, and is not limited to the manufacture of a crystal resonator element. Various methods or apparatuses for cutting the object to be formed by crystal are applied.

[Industry use possibility]

It is possible to cut the object to be processed by crystal with good dimensional accuracy.

1‧‧‧Processing objects

5‧‧‧ cut the booking line

7‧‧‧Modified area

L‧‧‧Laser light

S‧‧‧Change point

S ₁ ‧‧‧1st modified point

S ₂ ‧‧‧2nd modification point

Fig. 1 is a schematic configuration diagram of a laser processing apparatus used for forming a modified region.

FIG. 2 is a plan view of an object to be processed which is a target of formation of a modified region.

Fig. 3 is a cross-sectional view taken along line III-III of the object to be processed of Fig. 2;

Fig. 4 is a plan view of an object to be processed after laser processing.

Fig. 5 is a cross-sectional view taken along line V-V of the object of Fig. 4;

Fig. 6 is a cross-sectional view taken along line VI-VI of the object of Fig. 4;

Fig. 7 is a schematic configuration diagram of a laser processing apparatus according to the embodiment.

Fig. 8 is a partial cross-sectional view showing a reflective spatial light modulator of the laser processing apparatus of Fig. 7.

Fig. 9 is a schematic configuration diagram of another laser processing apparatus according to the embodiment.

Fig. 10 is a flow chart showing the manufacturing process of the crystal resonator element of the embodiment.

FIG. 11 is a schematic view for explaining a process of cutting an object to be a crystal wafer. FIG.

FIG. 12 is another schematic view for explaining an operation of cutting an object to be a crystal wafer. FIG.

[Fig. 13] (a) is a photograph showing the surface of the object to be processed in which the second modified spot is formed in the present embodiment, and (b) is a cross section taken along the line bb of Fig. 13 (a). Corresponding photos.

FIG. 14 is a photograph showing the surface of the object to be processed in which the second modified spot is formed in the comparative example.

1‧‧‧Processing objects

3‧‧‧ surface

5‧‧‧ cut the booking line

21‧‧‧Back

31‧‧‧Expanding tape

7‧‧‧Modified area

L‧‧‧Laser light

S ₁ ‧‧‧1st modified point

S ₂ ‧‧‧2nd modification point

S‧‧‧Change point

Claims (2)

A laser processing method is a laser processing method for cutting an object to be processed by a crystal along a line to be cut, and is characterized in that it is provided by collecting laser light a modified region forming process for forming a modified region including a plurality of modified spots at the object to be processed along the cutting target line, wherein the modified region forming project includes When the laser beam is irradiated onto the object to be processed, the laser beam is irradiated along the line to be cut, and a plurality of positions are formed along the line to be cut along the line to be cut. a project for modifying a mass point; and irradiating the laser beam with respect to the object to be processed, and moving relative to the predetermined line to be cut along the line to be cut, so as not to be exposed In the method of cracking the laser light incident surface of the object to be processed, a plurality of second modified spots exposed to the laser light incident surface of the object to be processed are formed. The laser processing method according to the first aspect of the invention, further comprising: applying a force to the object to be processed from the outside along the line to cut, the modified region A cutting process in which the object to be processed is cut as a starting point of cutting.