JP2006248885A - Cutting method of quartz by ultrashort pulse laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method of a comparatively large sized quartz. <P>SOLUTION: The quartz is cut by irradiating a cut area 2 of the quartz 1 with the ultrashort pulse laser having a pulse width of 1 picosecond to 100 nanosecond from a laser oscillator 11 and making a plurality of laser irradiation marks over the entire surface of the cut area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of cutting a relatively large size quartz by an ultrashort pulse laser.

  Quartz glass, including fused silica and synthetic quartz glass, has many excellent properties such as high purity, heat resistance, light transmission, chemical stability, and electrical insulation, and materials for optical components, semiconductor industry, etc. As widely used. However, while having such excellent characteristics, it is very hard and processing such as cutting is extremely difficult. At present, the material is fixed, and cutting is performed using a rotating disk or a band-shaped cutting machine in which a diamond is studded at the tip.

  Further, a technique using a laser is attracting attention as a new processing method for quartz glass. Quartz glass optically transmits light widely from ultraviolet to near infrared. Therefore, it has been tried whether a wide range of wavelengths can be applied to the processing of the glass. However, processing with ultraviolet laser light currently has a shortage of output and a limited processing depth. Further, far-infrared rays can be processed because they are almost absorbed by quartz glass. However, in the conventional cutting method using infrared laser light, the processing depth is as shallow as several millimeters (not exceeding 10 mm), so that it is thick. It is said that there is a difficulty as a cutting method for a plate or a block material having a certain thickness.

Under these circumstances, a workpiece dividing method using a laser beam (see Patent Document 1) is disclosed.
JP 2004-343008 A

  The technique disclosed in Patent Document 1 is a laser irradiation surface in a method of cutting a thin plate member including any of a sapphire substrate, a silicon carbide substrate, a lithium tantalate substrate, a glass substrate, a quartz substrate, and a silicon substrate. Create an altered layer from the opposite side (other side) side of the (single side) side to a predetermined depth (preferably 10 to 50% of the thickness), and apply a bending moment (external force) along the altered dividing line. It will be divided. In addition, although the quartz substrate is handled in parallel with other substrates, it is thought that it was mentioned as a kind of wafer. That is, it is considered that the technique of Patent Document 1 is not based on the recognition of the special property of quartz laser.

  The above-described cutting method using a rotating disk or a band-shaped cutting machine in which diamond is interspersed with the cutting method requires an enormous amount of time because the amount of cutting per unit time is extremely small. When subdividing from a long material or changing the size, since heat treatment is performed to take thermal strain (strain) in the vicinity of the cut surface after cutting, more time is required. In addition, since the cutting tool is easily worn out and requires frequent tool change, it takes time and money. This is a major negative factor in the production process.

  Further, in the dividing method of Patent Document 1, the object to be cut is limited to an extremely thin plate such as a wafer. This is because the means of applying a bending moment (external force) can only be used on thin plates such as wafers, and thick plates will be strongly re-welded immediately after melting even if they are altered by laser irradiation. This is because it is impossible to divide by the bending moment (external force). Dividing by this method is limited to a thickness of about 5 mm. When the thickness is about 10 mm, it is broken, and when it exceeds this, the division is impossible.

  Thus, there is a need for a new processing method that shortens the processing time of quartz and does not require tool replacement. In addition, it is a technique in which the cutting width is narrow in terms of yield, the cutting depth is not limited by the tooth width of the cutting tool, and it is desirable that thick quartz glass can be cut.

  The present invention has been made in view of the above problems, and an example of the object is to provide a method of cutting quartz with an ultrashort pulse laser.

The inventor of the present application has arrived at the present invention with the following recognition. The recognition is that quartz is expanded and melted by the irradiation heat of the ultrashort pulse laser and then cooled, whereby tensile stress is applied and a crack is generated. Here, OH groups such as moisture (H ₂ O) in the atmosphere or by forced supply react with the component Si of quartz to form Si—OH and further progress cracks.

  Based on this recognition, the present inventor has made the present invention to solve the above-mentioned problems.

  According to the present invention, an ultrashort pulse laser having a pulse width of 1 picosecond to 100 nanoseconds is irradiated on a cut surface of quartz, and a plurality of laser irradiation traces are formed over the entire cut surface. This is a quartz cutting method using a pulse laser.

  In the present invention, the laser beam is condensed on one end of the cut surface or in the vicinity thereof, a plurality of laser irradiation traces are arranged along the one end to form an alteration line, and then the condensing point of the laser beam is set in the other end direction. This is a quartz cutting method using an ultra-short pulse laser characterized in that an altered line is formed again and an altered line is formed again, and thus an altered line is formed by a plurality of laser irradiation marks over the entire cut surface. The cutting plane can be a vertical plane, a horizontal plane or a slope.

  The invention of the present application is a method for cutting quartz by an ultrashort pulse laser, wherein the cutting surface is a surface or an inclined surface perpendicular to the laser irradiation direction. Here, the cut surface is a surface perpendicular to the laser irradiation direction, for example, as shown in FIG. 7, when the laser is irradiated from above quartz, the cut surface is horizontal (horizontal). It is.

  Further, the present invention irradiates a laser beam from one side of quartz and condenses it on the other surface side or the vicinity thereof, arranges a plurality of laser irradiation traces along the other surface side, creates an altered line, and then A method for cutting quartz with an ultrashort pulse laser, characterized in that the focal point is displaced inward in the thickness direction of the quartz to create an altered line again, and thus the altered line is successively formed over the entire cut surface. It is. When the laser is irradiated from above the quartz, if the cut surface is a vertical surface (or a nearly vertical slope), the laser is irradiated near the lower surface of the quartz, and the laser irradiation traces are arranged along the lower surface to create an altered line. Then, it is necessary to displace the laser condensing point in the upper surface direction and make a similar alteration line above the previous alteration line (see FIG. 4). This is because if the alteration lines are arranged from the vicinity of the upper surface to the lower surface, the laser interferes with the already altered portions, and the alteration lines cannot be arranged sequentially in the lower direction. When the cut surface does not extend from the upper surface to the lower surface, that is, when creating a cut surface from the upper surface to the vicinity of the quartz middle, start laser irradiation from the middle of the quartz and overlap the alteration line toward the upper surface side. It becomes. Similarly, when the cut surface extends from near the middle of the quartz to the lower surface, the altered line is overlapped from the lower surface to the middle.

  Further, the present invention is a quartz cutting method using an ultrashort pulse laser, wherein adjacent laser irradiation traces among the plurality of laser irradiation traces are made to partially overlap each other.

  Further, the present invention is a method for cutting quartz by an ultrashort pulse laser, wherein a temperature difference is given to the cut surface after forming the plurality of laser irradiation traces.

  In the present invention, the ultrashort pulse laser to be used is a YAG fundamental wave having a wavelength λ = 1,064 nm, and the pulse output is 10 mJ (millijoule) or more. This is a cutting method.

  According to the present invention, it is possible to provide a quartz cutting method using an ultrashort pulse laser. This eliminates the need for tool replacement and shortens the machining time. Furthermore, the cutting width can be narrowed and the depth can be further increased. Further, even thick quartz can be cut without applying external force. At present, it is presumed that the quartz block cannot be cut by laser other than this method.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. Note that the present invention is not limited to this embodiment.

  In FIG. 1, the quartz 1 is placed directly on the XYZ table 12, or is fixed by a jig (not shown). A laser oscillator 11 is provided above the quartz 1 so as to oscillate a laser on the cut surface 2 of the quartz 1.

  Quartz 1 is, for example, quartz glass including fused quartz or synthetic quartz glass. Further, the quartz 1 is cut by the cut surface 2.

  The laser oscillator 11 is a laser oscillator that can oscillate an ultrashort pulse laser.

  The XYZ table 12 is a table that can move in the XYZ axis directions at an arbitrary speed. By moving the XYZ table 12 on the quartz 1 and moving in the XYZ axis direction, the laser oscillator 11 can irradiate an arbitrary position in the quartz 1 with an ultrashort pulse laser.

  When the laser oscillator 11 oscillates an ultrashort pulse laser from the upper side of the quartz 1 with the focal point in the quartz 1, a laser irradiation mark 3 as shown in FIG. 2 is formed. This laser irradiation mark 3 is a micro crack (crack) due to a change in physical properties, and propagates short in the direction opposite to the incident direction. Further, the laser irradiation mark 3 has a vertically long elliptical shape, and the size of the laser irradiation mark 3 is usually about 0.3 mm in the length of the elliptical short axis direction and about 0.2 mm in the length of the elliptical long axis direction. 6 to about 1.5 mm. However, it is not limited to this size. If a long focus lens is used, the depth of focus can be increased and the laser irradiation mark 3 can be elongated in the direction of the ellipse long axis.

  As shown in FIG. 3, the quartz can be cut by making the laser irradiation marks 3 over the entire cut surface 2 of the quartz 1.

  Hereinafter, an example of a method for forming the laser irradiation trace 3 over the entire cut surface 2 of the quartz 1 will be described with reference to FIG. The focal point of the laser is moved by operating the XYZ table 2.

  First, the focal point of the laser is aligned with the vicinity of the lower left corner of the cut surface 2, and the focal point of the laser is moved laterally each time an ultrashort pulse laser is irradiated from there. At that time, the ultrashort pulse laser is irradiated so that the laser irradiation marks 3 are in contact with each other or partially overlap (for example, 10% to 30%). However, if it overlaps too much, the laser beam cannot be turned on because it interferes with the already altered part. The focal spot is moved laterally until the laser irradiation mark 3 reaches the side surface of the quartz 1. Then, the laser irradiation traces 3 are arranged in the minor axis direction, and an altered line 4a is formed by the laser irradiation traces 3.

  Next, the focal point of the laser is moved upward (inward in the thickness direction) along the cut surface, and the same altered line 4b is formed above the altered line 4a. At this time, the altered line 4b is formed so that the upper part of the altered line 4a and the lower part of the altered line 4b are in contact with each other or partially overlap.

  Furthermore, the same altered line is made upward (inward in the thickness direction) 4c, 4d,..., 4j. Then, as shown in FIG. 3, the alteration lines 4 are arranged in parallel to fill the entire cut surface 2. In other words, the laser irradiation mark 3 is formed over the entire cut surface 2. Here, the parallel alteration line group which fills up this cut surface 2 is collectively called an alteration line surface. In addition, the dotted line arrow of FIG. 4 is an example which showed the movement line 5 of the focal point of a laser.

  Since physical property changes occur on the altered line surface thus formed, cracks progress due to reaction with moisture in the atmosphere over time. And the quartz 1 is isolate | separated by the quality change line surface.

  Moreover, a crack can be advanced by heating or cooling an alteration line surface moderately. Therefore, the separation time can be controlled by giving a temperature difference in the vicinity of the alteration line surface. Various means for giving the temperature difference are conceivable, and examples include air cooling by leaving it alone and rapid heating or cooling by an artificial method. Specifically, it is conceivable to supply cooling water or oxygen to promote the reaction. Further, there is a method in which an acidic aqueous solution or the like is added by applying pressure along the altered line surface.

  By such a method, it is possible to realize cutting of quartz, which has been difficult to process with a conventional focused laser.

  Furthermore, other embodiments will be described. As shown in FIG. 7, a laser is emitted from above the quartz 1 by a laser oscillator 11, and the entire cut surface 2 that is horizontal (perpendicular to the laser irradiation direction) is filled with laser irradiation marks 3. Can be separated. In the embodiment shown in FIG. 4, the altered lines are sequentially stacked upward (inward in the thickness direction), but in this embodiment, the altered lines are sequentially arranged in the horizontal direction. Here, cutting / separation is possible by making the laser irradiation trace 3 over the entire cut surface 2, but it is efficient if the alteration lines are arranged in order from one end of the cut surface to the other end. . In FIG. 7, the rows of laser irradiation traces 3 (altered lines) are arranged in the horizontal direction, and the cut surface 2 forms one layer of altered line surface, but two or more layers of altered line surfaces are overlapped. You can also. By doing so, the progress of cracks is accelerated, and cutting and separation are possible in a short time. However, the yield of the material becomes worse. In this way, cutting and separation can be performed on a horizontal plane (XY plane), and members can be cut out, such as slicing a quartz block.

  Next, an embodiment in which a member is cut out from the quartz block will be described. As shown in FIG. 8, the quartz member 7 can be cut out by combining the cut surfaces of the vertical plane (XZ plane, YZ plane) and the horizontal plane (XY plane). When cutting along a vertical plane (XZ plane, YZ plane), it is preferable to superimpose an alteration line in the direction of the arrow 6a in the figure. This is because if the altered lines are arranged in the opposite direction of the arrow 6a, the laser interferes with the already altered part.

  Furthermore, as shown in FIG. 9, the quartz member 8 can be cut out by inclining the cut surface. In order to cut the quartz 1 along the inclined surface, it is only necessary to irradiate the laser from above the quartz 1 with the laser oscillator 11, arrange the altered lines in order on the cut surface, and fill the entire cut surface with laser irradiation marks. Here, when the inclination angle of the cut surface is close to vertical, it is preferable to sequentially superimpose the altered lines in the direction of the arrow 6b in the figure in order to avoid laser interference. On the other hand, when the inclination angle of the cut surface is close to horizontal, cutting is possible even if the altered lines are sequentially arranged in the reverse direction of the arrow 6b.

  In this way, quartz can be cut along a vertical plane, a horizontal plane, or a slope. Various quartz processing is possible by combining these.

  Here, as the ultrashort pulse laser used in the present invention, a YAG laser fundamental wave (wavelength λ = 1,064 nm) whose oscillation time is made extremely short by any method can be used. In a YAG laser, laser light that is pulse-oscillated in an extremely short time (for example, a pulse width of several nanometers to several tens of nanoseconds) can be usually obtained by a Q switch method. For example, there is a Q switch mechanism (rotary shutter) as shown in FIG. The laser oscillator 11 includes a total reflection mirror 13, a laser substance 14, a partial reflection mirror 15, and a rotary shutter 16. A high-power optical pulse can be generated by inserting a rotary shutter 16 for preventing oscillation into the laser oscillator 11 and opening it momentarily. In addition, laser light that is pulse-oscillated in a very short time (for example, a pulse width of several pico to several tens of pico seconds) can be obtained by the mode lock method. In addition, an ultrasonic Q switch (Acoustic Q-Switching) or a Pockels cell Q-Switching (Pockels cell Q-Switching) that has excellent responsiveness and can adjust the emission timing and pulse width is often used.

  FIG. 6 shows oscillation waveforms of continuous oscillation, pulse oscillation, and Q switch pulse oscillation. As shown here, laser light having a high output and a narrow pulse width (pulse oscillation time) can be obtained by the Q switch.

  Any laser that oscillates an ultrashort pulse may be used. In the future, when a high output is realized, it is considered that the object can be achieved also by an ultrashort pulse laser having a different wavelength (for example, wavelength λ = 800 nm). At present, it has been confirmed that cutting is possible even with lasers having wavelengths λ = 532 nm and λ = 355 nm.

  In the present embodiment, the XYZ table 12 capable of moving in the XYZ axis directions at an arbitrary speed is used as a method for appropriately shifting the focal point. However, the focal point may be shifted by making the laser oscillator 11 movable. it can.

  The incident angle Θ of the laser with respect to quartz is preferably about 0 to 15 degrees (see FIG. 10). This is because if the laser beam is irradiated at a larger incident angle, the laser beam is reflected and the laser beam cannot enter the quartz.

It is a schematic diagram of the cutting method of the quartz by the laser concerning this invention. It is a figure which shows the laser irradiation trace of the cut surface shown in FIG. It is sectional drawing which looked at the cut surface shown in FIG. 1 from the dashed-dotted arrow direction. It is a state diagram in operation of a laser irradiation trace. It is an example figure of Q switch by a rotary shutter. It is a figure which shows the oscillation waveform of continuous oscillation, pulse oscillation, and Q switch pulse oscillation. It is a state figure which is irradiating a laser to a horizontal cut surface. It is the state figure which cut out the part from the quartz block. It is the state figure which cut out the part from the quartz block. It is the figure which showed the incident angle of the laser to quartz.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Quartz 2 Cut surface 3 Laser irradiation trace 4a Alteration line 4b Alteration line 4c Alteration line 4d Alteration line 4e Alteration line 4f Alteration line 4g Alteration line 4h Alteration line 4i Alteration line 4j Alteration line 5 Laser focal point movement line 7 Member 8 Quartz member 11 Laser oscillator 12 XYZ table 13 Total reflection mirror 14 Laser substance 15 Partial reflection mirror 16 Rotating shutter

Claims (7)

  Quartz by an ultrashort pulse laser characterized in that an ultrashort pulse laser having a pulse width of 1 picosecond to 100 nanoseconds is irradiated on the cut surface of the quartz, and a plurality of laser irradiation traces are formed over the entire surface of the cut surface. Cutting method.   The laser beam is condensed on one end of the cut surface or in the vicinity thereof, a plurality of laser irradiation traces are arranged along the one end to form an altered line, and then the focal point of the laser beam is displaced in the other end direction to alter again. 2. The method for cutting quartz with an ultrashort pulse laser according to claim 1, wherein a line is formed, and thus an altered line is formed by a plurality of laser irradiation marks over the entire cut surface.   3. The method for cutting quartz with an ultrashort pulse laser according to claim 1 or 2, wherein the cutting plane is a plane or a slope perpendicular to the laser irradiation direction.   A laser beam is irradiated from one side of the quartz and condensed on the other side or in the vicinity thereof, a plurality of laser irradiation traces are arranged along the other side to create an altered line, and then the focal point of the laser beam is set to the quartz 3. A method for cutting quartz with an ultrashort pulse laser according to claim 1 or 2, wherein a modified line is formed again by displacement inwardly in the thickness direction, and thus a modified line is formed in sequence over the entire cut surface. .   5. The method for cutting quartz with an ultrashort pulse laser according to claim 1, wherein adjacent laser irradiation traces of the plurality of laser irradiation traces are made to partially overlap each other.   6. The method for cutting quartz with an ultrashort pulse laser according to claim 1, wherein after the plurality of laser irradiation traces are formed, a temperature difference is given to the cut surface.   The ultrashort pulse laser used is a YAG fundamental wave having a wavelength λ = 1,064 nm, and the pulse output is 10 mJ (millijoule) or more. Cutting method.

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