JP2006035710A - Glass processing method using laser and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser cutting method for cutting a glass for enabling improvement of processing precision and processing speed, in which a first laser is cast along a cutting line for modification by using very high frequency pulse laser and a second laser is cast to a modified part for cutting. <P>SOLUTION: In the cutting and processing method of glass, a crack is generated by a heat source using a processing start point provided on a work made of glass as a starting point, and the crack is extended along a planned cutting line. The first laser is irradiated to the processing start point so as to modify a glass main component of SiO<SB>2</SB>to Si or Si<SB>x</SB>O<SB>y,</SB>or to generate the modified part containing free radicals of B, Na, K, Ca, Zn, Al or Pb from at least one component of glass such as B<SB>2</SB>O<SB>3</SB>, Na<SB>2</SB>O, K<SB>2</SB>O, CaO, B<SB>2</SB>O<SB>2</SB>, ZnO, Al<SB>2</SB>O<SB>3</SB>, PbO or the like. The second laser is cast to the modified part so that the modified part absorbs light energy and discharges thermal stress energy resulting from local thermal expansion so as to cut the glass. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention heats a brittle material such as glass or ceramic by locally irradiating a heat source such as a laser, a burner, a light source, or an electric heater, and cleaves the brittle material using thermal stress generated by the heating. The present invention relates to a cleaving method and apparatus therefor, and a method of manufacturing an electronic component using them.

  In the manufacture of flat panel displays consisting of electronic components such as liquid crystal devices and organic electroluminescence (hereinafter referred to as “organic EL”) devices, or the manufacture of wafers of semiconductor materials, etc., large-area glass substrates, silicon, etc. After a plurality of elements are formed on a wafer made of the above, a method of obtaining a panel or chip (product) having a required dimension by dividing into a plurality of elements is adopted. A process of cleaving along a predetermined planned cutting line is essential.

  As a method of cutting a workpiece such as a glass substrate made of such a brittle material, (a) a sharp tip or a sharp peripheral edge of a carbide tool such as a diamond tool is pressed against the workpiece surface and moved. To form a groove (scribe line) along the planned cutting line on the surface of the workpiece, and then apply a mechanical impact force such as bending or pulling to the workpiece along the groove, or (b) laser By focusing the beam with an optical system and irradiating the surface of the workpiece with a minute spot, locally melting or evaporating the workpiece, and scanning the irradiation position of the laser beam along the planned cutting line There are methods such as cleaving the workpiece.

  However, in the method (a), it takes a very long time to cut, and it is difficult to cleave long and complicated bends. In the method (b), the substance dissolved or evaporated by the laser beam irradiation adheres to the work piece or the element on the work piece and deteriorates the conductivity of the electrode part of the work piece. Microcracks may be generated due to thermal effects, causing the workpiece to deteriorate. Furthermore, since the spot diameter cannot be narrowed down even if the laser beam is narrowed down, there is a problem that the cutting width cannot be eliminated, and loss of material due to evaporation or the like cannot be avoided.

  Therefore, recently, by forming a notch or chamfering starting point on the workpiece and irradiating a laser beam in the vicinity of the starting point, compressive stress acting on the beam center and tensile stress acting on the periphery Cracks that extend from the center of the beam to the processing start point are generated by the thermal stress caused by the laser, and then the laser beam is moved along the direction to be cleaved. A method of cleaving a workpiece has been proposed. One example is the invention disclosed in Japanese Patent Laid-Open No. 1-108006.

As a heat source for heating, a burner, a light source, an electric heater, or the like can be used in addition to the laser. When irradiating a laser as a heat source that generates cleaving for the workpiece, if the wavelength of the workpiece is transparent to the laser light used, the laser absorption may be applied to generate laser absorption. It is disclosed in JP-A-9-253879.
JP 50-114422 A JP 54-106524 A JP-A-1-108006 JP-A-9-253879 JP 2000-61676 A JP 2003-154517 A

  The cleaving method for brittle materials using thermal stress from a heat source such as a laser as described above causes cracks that have occurred at the processing start point formed on the workpiece to continuously progress to the processing end point. It is important to control the generation direction to a specific direction, that is, the machining end point direction, and the formation and accuracy of the machining start point that is the starting point of the crack generation greatly influences the cleaving accuracy for the workpiece. This starting point can be formed by forming a notch at the end of the workpiece using a hard tool such as diamond glass cutter, or focusing a high-power laser beam on the surface of the workpiece. Then, there is a method of processing a hole and forming a crack from the hole.

  However, in the above method, a large number of microcracks that can be the starting point of cracks are generated at the peripheral edge of the notch formed at the end of the workpiece 1, and the crack generation direction is set to a specific direction. It was difficult to control, and as a result, there was a problem that high cleaving accuracy for the workpiece could not be obtained. In addition, when forming a notch, the hard tool comes into direct contact with the workpiece. For example, if dust adheres to the hard tool, the dust contaminates the workpiece, and therefore the notch There was also a problem that the film could not be formed accurately.

  Furthermore, since the processing waste of the workpiece 1 is generated when the notch is formed, the processing waste contaminates the surrounding environment, adheres to the workpiece, and adversely affects the electrode portion of the element on the workpiece. There are also problems such as generating defective products and reducing the yield. And in order to remove the processing waste adhering to the workpiece, in the cleaving process for the workpiece, the cleaving process must be added after the formation of the notch, making the cleaving process complicated.

  In the case of this method as well, there is a problem that, as described above, micro cracks are generated in the peripheral portion of the hole and processing scraps are generated, so that high cleaving accuracy for the workpiece cannot be obtained. Further, as the size of the glass plate increases with the increase in size of the liquid crystal panel, it becomes difficult to cleave, and the yield of processing success is reduced.

  The present invention has been made in order to solve the above-described problems, and in a technique for generating and cleaving a crack by thermal stress caused by heating of a heat source, a processing start point that is the starting point of the crack is accurately formed. An object of the present invention is to provide a cleaving method and apparatus capable of improving cleaving accuracy for a workpiece, and a method for manufacturing an electronic component. Conventionally, the method of applying a light-absorbing paint in advance to the position where the laser is to be cleaved has a problem of requiring extra affirmation such as cleaning after cutting.

The present invention, SiO ₂ of the light-absorbing to the glass prior to the cleaving step of the workpiece, such as _{glass, B 2 O 3, Na 2} O, K 2 O, CaO, B 2 O 2, ZnO, Al 2 O 3 , PbO is a material containing Si _x O _y (where x is other than 1 and y is other than 2) or free radicals such as B, Na, K, Ca, Zn, Al, Pb by the first laser. The reforming part is generated in the reforming process of ultrashort pulse irradiation. This portion is subjected to laser energy irradiation to such an extent that no change in shape such as a flaw can be seen only by the ultrashort pulse irradiation, thereby causing a material modification. The material modification does not occur with a CW laser or a normal long pulse, but the material modification occurs instantaneously due to the high electric field at the laser focusing point of the ultrashort pulse.

  If necessary, the glass surface may be composed of an atmospheric gas other than the atmosphere. Therefore, the material removal in the method of providing a cut with a laser as a starting point of the cleaving process, which has been conventionally performed prior to cleaving, does not necessarily have to occur.

The modified part of this component contains Si _x O _y (where x is other than 1 and y is other than 2) or free radicals such as B, Na, K, Ca, Zn, Al, Pb, etc. As a result, a change occurs in the light absorption spectrum characteristics, so that an increase in absorption rate can be obtained even with lasers other than the wavelength of the ultrashort pulse laser used for the modification. By this ultrashort pulse irradiation, a modified portion is generated along the cutting line, and a modified portion having a high light absorption rate is formed along the line. Next, irradiation with a second long-pulse or CW laser having a wavelength range having light absorption obtained by the modification along the modified line generates heat in the modified part and causes heat-induced stress. Occurs around the irradiated portion of the modified portion irradiated with the laser.

  If the laser focusing point is moved along the modified line, it is possible to generate cleaving according to the stress distribution. In order to generate the cleaving start point from the edge of the glass, no special pretreatment other than the beam irradiation for modification is required. For this reason, it becomes possible to use the laser beam which is a transparent wavelength with respect to the glass which could not be conventionally used as a split heat insulation source as a heat source. This means that an ultrashort pulse laser with low oscillation efficiency can be used simply for reforming, and a laser source for cutting can use laser oscillation output power that can provide an oscillation efficiency much higher than the oscillation efficiency of ultrashort pulses.

  As an effect of the present invention, in this invention, a locally modified portion of the glass material is generated under the high electric field of the focused spot by irradiating the transparent glass with an ultrashort pulse, and conventionally, it can be used as a split heat insulation source. It was made possible to use the laser light in the transparent wavelength range for the glass that was not used as a heat source for cleaving. This means that an ultrashort pulse laser with a low oscillation efficiency can be used simply for modification, and a heat source for cleaving can be a long pulse laser or a CW laser that can obtain an efficiency much higher than the oscillation efficiency of an ultrashort pulse. .

Therefore, a CO ₂ laser has been used exclusively as a heat source in the past. However, by using the method of the present invention, a fundamental laser of a solid laser such as Nd: YAG, a harmonic, or a fiber laser added with a semiconductor laser, YB, Er, etc. Can be used. As described above, since it is possible to use a laser capable of power transmission with an optical fiber as a heat source, the degree of freedom in designing a cleaving system such as a large liquid crystal panel is increased.

A method of cutting a transparent body such as glass, where a crack is generated by using a heat source as a starting point provided on the workpiece, and further progressing along a planned cutting line to cleave the workpiece. It is a processing method, and the processing start point is irradiated with a first laser, and SiO ₂ which is a main component of glass is changed to Si or Si _x O _y , other B ₂ O ₃ , Na ₂ O, K ₂ O, CaO, One of the glass components such as B ₂ O ₂ , ZnO, Al ₂ O ₃ and PbO is modified by the first laser into a composition containing free radicals such as B, Na, K, Ca, Zn, Al and Pb. Then, the modified portion is irradiated with a second laser having an oscillation characteristic of another oscillation mode having light absorption characteristics, so that the modified portion absorbs light energy and releases stress energy associated with local thermal expansion. To cut the glass. The a laser glass cutting method, wherein, will be described with reference to FIG. 1 the implementation.

  FIG. 1 shows a schematic configuration of an embodiment of the present invention. The first laser oscillator is an ultrashort pulse laser oscillator. The output wavelength of the diode laser pumped solid-state laser is doubled to excite the Ti-added sapphire crystal, and this laser gain medium is installed in the mode-locked laser resonator. Oscillates an ultra-short pulse. The ultrashort pulse laser beam 3 is obtained by amplifying as necessary. In addition, a well-known ultrashort pulse oscillator, for example, a mode-locked pulse is oscillated from an Er-doped optical fiber, the output is made into a second harmonic ultrashort pulse with a nonlinear crystal, and amplified as necessary to obtain an ultrashort pulse. Methods can also be used. Other known ultrashort pulse oscillation techniques are used.

The laser beam 3 is directed by the reflecting mirror 4 toward the condensing lens 7, and the condensing spot is directed toward the glass processed body 14 to irradiate the portion 10. In the processed body 14, silicon dioxide, which is a component of glass, is decomposed and modified by a strong electric field that can be formed in the focal point region of an ultrashort pulse, and the constituent components are changed like Si _x O _y to be modified. . Among the other components such as B ₂ O ₃ , Na ₂ O, K ₂ O, CaO, B ₂ O ₂ , ZnO, Al ₂ O ₃ , PbO, etc., B, Na, K, Free radicals such as Ca, Zn, Al, and Pb may appear in the modified portion. The workpiece 14 is mounted on the moving stage 13 and the focal point of the lens is moved parallel to the surface of the workpiece as indicated by the arrow 15 to modify the portion 12 of the workpiece.

  In this irradiation step, it is not always necessary to remove the material on the glass surface. After this first laser irradiation, a beam 8 having a larger energy is emitted from the second laser 2 toward the reflecting mirror 5, and the first laser beam is irradiated by the condenser lens 9, and the modification is performed. The condensing point 16 of the lens 9 is positioned so as to condense toward the part. That is, when the modified portion 12 is sent in the direction of the arrow on the moving stage, the modified portion 12 is arranged to move to the condensing point 16 of the second laser. The second laser is a long pulse oscillation or a CW oscillation, and is generally a laser capable of realizing an output with a higher average output with a higher oscillation efficiency than an ultrashort pulse oscillation. By irradiating the modified portion with the laser beam having a large average power, the first laser is modified even at a wavelength at which the second laser beam is not sufficiently absorbed by the original component of the glass. Since the light absorptance is increased, the second high average output beam is efficiently absorbed in the portion modified by the first laser to form a fine heat source.

  The heat source of this fine modified portion forms a large stress distribution in the surrounding area, and when the first and second beams are scanned from the end of the glass processed body 14, the glass starts to break along the modified portion. To do. In this direction, the cleaving proceeds along the modified portion of the planned cutting portion formed by the first laser. If the modified portion is formed by the first laser along the planned cutting line, even if the spot size of the condensing point of the second laser beam is larger than the scanning line width of the modified portion, the second portion Since the laser absorption is limited to the first modified portion, the heat source is also formed in the modified portion by the first laser, and the irradiation position accuracy of the first and second condensing points is the first. The cutting position accuracy is determined by the laser irradiation position accuracy.

  Therefore, if the irradiation position of the ultrashort pulse, the spot size, the laser pulse energy required for modification, and a condensing optical system excellent in condensing property are used, high-precision cleaving is determined, and the second laser has the first laser irradiation accuracy. It suffices to irradiate with a large amount of energy sufficient to execute the completed cleavage. Therefore, the irradiation position accuracy of the second laser does not directly affect the cleaving position accuracy, and a high performance with excellent light collection performance is not necessarily required in selecting the laser beam quality. It is sufficient to secure enough.

This is because, in the conventional cleaving using a CO ₂ laser, the light condensing performance and the irradiation position accuracy directly affect the cleaving accuracy, and the advantages of the method of the present invention in terms of large apparatus production and glass cutting performance. It is a point. The first laser has a pulse width of several femtoseconds to 500 femtoseconds, and the second laser has an ultraviolet laser (such as SHG, THG, FHG, etc. of Nd: YAG laser) to an infrared laser (Nd). : YAG laser) solid-state laser or gas laser can be applied.

  The above laser irradiation has been described with respect to the method of irradiating the second laser with the movement time interval of the moving stage following the irradiation with the first ultrashort pulse laser. May be arranged coaxially, and pulses may be superimposed simultaneously or alternately in time.

  As an example of the present invention, when irradiating the second laser in Examples 1 and 2, in order to efficiently cleave the glass even when the second laser power is reduced, the glass is perpendicular to the breaking line. It is effective to adopt a moving stage that applies a bending moment to the surface. In this case, a configuration in which the protruding objects are linearly arranged on the plane moving stage along the breaking line, and a pressing force is applied to the stage between the active lines of glass is simple and effective. The pressing force can apply a bending moment along the breaking line by reducing the pressure between the moving stage and the glass with a vacuum pump.

  In addition, a roller is provided on the back surface along the breaking line, and two rollers are arranged on both sides of the breaking line on the front surface, and a bending moment is applied by moving the glass plate between the rollers along the breaking line. By using a known mechanism in combination, the average power of the second laser required for cleaving can be reduced and the cleaving speed can be improved.

  As an application example of the present invention, after forming elements for a plurality of large-sized glass substrates such as manufacturing of flat panel displays composed of liquid crystal devices which are electronic components, devices such as organic electroluminescence, plasma display, etc. It can be applied to a method of dividing and obtaining a panel having a required dimension.

Schematic configuration diagram of Example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 .... 1st laser oscillator, 2 .... 2nd laser oscillator, 3, 6 .... Ultrashort pulse laser beam, 4 .... Reflection mirror, 5 .... Reflection mirror, 7 .... Condensing lens, 8. ... long pulse laser or CW laser,
9 .... Condensing lens, 10 .... Condensing spot for surface modification, 11 .... Cleavage part, 12 .... Glass modification part, 13 .... Moving stage, 14 .... Workpiece, 15 .... Moving stage direction (For explanation), 16 .... second laser focused spot

Claims (11)

  A cleaving method for cleaving the workpiece by causing cracks to propagate along a planned cleaving line of the workpiece by a heat source, wherein the focused spot of the first laser beam is scanned and irradiated along the surface of the workpiece. The main component of the workpiece is modified by the first laser beam, and the modified laser is irradiated with the second laser beam to selectively absorb the light energy, and the modified unit is subjected to local thermal expansion. Laser cutting method characterized by causing thermal stress accompanying it and cleaving   The laser cutting method according to claim 1, wherein the first laser beam is an ultrashort pulse laser beam.   2. The laser cutting method according to claim 1, wherein the second laser is a continuous wave mode or pulse mode ultraviolet laser beam.   The laser cutting method according to claim 1, wherein the second laser is an infrared laser.   The first laser is a femtosecond laser, and the second laser is a third harmonic of an Nd: YAG laser.   The laser cutting method according to claim 3 or 4, wherein the cutting start point is irradiated with a femtosecond laser to make a scratch.   2. The laser cutting method according to claim 1, wherein the workpiece is a glass plate. Including in claim 1 or claim 8, the glass component _{SiO 2, B 2 O 3,} Na 2 O, K 2 O, CaO, B 2 O 2, ZnO, at least one of _Al 2 O 3, PbO A laser cutting method characterized by being made of glass. Claim 1, in any one of claims 8 or claim 9, at least _B 2 _O 3 modification of the glass as a glass _{component, Na 2 O, K 2 O} , CaO, B 2 O 2, ZnO, Al _{It has one of 2} O ₃ and PbO and has a modified part containing free radicals such as Si, Si _x O _y or B, Na, K, Ca, Zn, Al, Pb by the first laser irradiation. A laser cutting method characterized by the above.   2. The laser cutting method according to claim 1, wherein the generation shape of the modified portion by the first laser is one line or a plurality of lines.   The generation of glass cleaving in which a bending moment is applied in a direction crossing the cleaving direction at the time of irradiation of at least the second laser cleaving planned portion at the laser cleaving position of the glass plate installation stage is promoted. 1. Laser cutting method.

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