JPH08174260A - Laser machining method and its device - Google Patents

Abstract

PURPOSE: To provide a laser machining method and its device which are capable of machining a part irradiated with a laser beam into a smooth finish. CONSTITUTION: The wave length of a beam generated by a carbon dioxide gas laser device 121 is controlled into a single wavelength by selecting with a diffraction grating 112; and this laser beam with the single wavelength is converged while an assist gas is made to flow on the outer circumference of the laser beam along its transmitting direction. Then, on the optical path of the laser beam, a shutter 132 is arranged which is provided with a mirror function; and the output voltage of the drive source 138 is controlled so as to make the light power constant by monitoring the reflected light with an optical power meter 137.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and apparatus for processing a workpiece such as a non-metal material in a non-contact manner with a laser beam of a carbon dioxide gas laser device or the like.

[0002]

2. Description of the Related Art Recently, glass material substrates, magnetic material substrates,
BACKGROUND ART Product development of devices in which electronic circuits, optical circuits, etc. are mounted on semiconductor material substrates, and further on dielectric material substrates, has been actively conducted. Several to several thousand of these devices are formed in the substrate or on the front (or back) surface. Therefore, in the final step, the substrate must be cut to separate the devices. As a cutting / separating method, as shown in FIG. 6, a method of performing diamond blade dicing along a dotted line, or a method of irradiating with laser light to perform scribing is used.

FIG. 7 shows a glass cutting apparatus proposed by the applicant of the present invention by irradiating a CO ₂ laser beam (Japanese Patent Application No. 5-63).
775). This apparatus blows an assist gas G around a laser beam L of a CO ₂ laser (carbon dioxide gas laser) 801 from an assist gas introduction tube 802, irradiates the glass substrate 804 on a base 803 with this glass L When cutting the substrate into two substrates A and B, the glass substrate is provided with the base 8 on the A side and the B side, respectively.
03 is vacuum-adsorbed and fixed. Base 803
The groove 805 provided between the A side and the B side is such that the laser light L penetrates the glass substrate 804, and the presence of the groove 805 makes it possible to maintain the same cutting conditions during cutting.

[0004]

It has been found that the following problems occur when the quartz-based and multi-component glass substrates, and the ceramic substrates such as mullite and alumina are cut by using the apparatus shown in FIG. (1) As shown in the plan view of FIG. 6 (a) and the side view of FIG. 6 (b), when the substrate material 901 having a thickness of 0.2 mm to 1.5 mm is cut, the cut substrate material is cut. Unevenness occurred on the front surface 903, the side surface 904, and the back surface 905 of the cut portion 902 of 901, and smooth cutting could not be performed.
However, there were some parts that were smooth. The size of the unevenness was several μm to several tens μm.

(2) In the device of FIG. 7, even if an attempt is made to measure the optical power immediately before cutting, the XYZ moving device 803 interferes and an optical power meter having a large volume cannot be installed in the passage of the laser beam. Therefore, it was not known every time whether the value of the optical power at the time of cutting was constant. In particular, when cutting materials having different substrate thicknesses, the value of the optical power must be set to the optimum value. However, the relationship between the current value of the power supply circuit of the device of FIG. 7 and the value of the optical power. Was found to change each time the device was operated, and it was difficult to know the value of the optical power immediately before cutting. An optical power meter can be installed by moving the XYZ moving device 803.
Since the moving device is a high-precision device with a resolution of the order of μm, it is difficult to precisely align the cutting area if it is moved every time, and the substrate is highly accurately measured at the focal position of the laser beam every time. It was also difficult to set the surface.

The object of the present invention is to solve the above-mentioned problems of the prior art, and to form a workpiece such as a substrate made of a non-metal material such as glass or ceramics or a non-metal material partially containing a metal material. Another object of the present invention is to provide a laser processing method and apparatus capable of smoothly cutting or forming processing such as cutting, slits, grooves, and markers (letters, numbers, pictures, etc.).

[0007]

In order to achieve the above object, the present invention adopts the following constitution.

That is, the laser processing method of the present invention is a method for processing a workpiece by irradiating the workpiece with a laser beam emitted from a laser device and then irradiating the laser beam on the optical path of the laser beam. This is a laser processing method in which a shutter having a mirror function for switching between reflection and transmission is arranged, and blocking and opening of laser light is controlled by this shutter.

The laser device is provided with a resonator having a grating capable of selecting a laser beam having a desired wavelength,
It is particularly preferable to obtain laser light of a single wavelength with this resonator.

Further, it is preferable to monitor the laser light reflected by the shutter and to control the output of the laser device so that the monitored optical power becomes constant.

Next, the laser processing apparatus of the present invention comprises a laser device for emitting a laser beam, a condensing lens for condensing the laser beam output by the laser device on the surface of the processed material, and this converging lens. In a laser processing device having at least a gas introduction mechanism for flowing an assist gas between the light lens and the surface of the material to be processed, between the laser device and the condenser lens,
The laser processing apparatus is provided with a shutter having a mirror function for reflecting and blocking the laser light or transmitting and opening the laser light.

It is particularly preferable to provide the laser device with a resonator having a grating capable of selecting a laser beam having a desired wavelength.

Further, an optical power meter for monitoring the laser light reflected by the shutter may be provided, or the output signal of the optical power meter may be fed back to the drive power source of the laser device so that the monitored optical power becomes constant. Good.

Further, between the shutter and the condenser lens,
A mirror that bends the optical path of the laser light at 90 ° may be provided.

Further, an electric drive type moving stage for moving the material to be processed in at least the X direction or the Y direction may be provided.

A laser device, a shutter, a mirror,
The condenser lens, the gas introduction mechanism, the moving stage, and the like may be integrated and fixed on a vibration-proof table having a vibration-proof function.

[0017]

The present invention was discovered by repeating various experiments using the apparatus of FIG. 7 previously proposed by the present inventor. That is, when glass or ceramics is cut as shown in FIG. 6, the surface of the substrate cut as shown in FIG.
Irregularities were generated on the side surface and the back surface, and the manner of generating the irregularities was irregular, and the state of the cut surface was changed each time it was performed. Further, since the composition is strongly influenced, the wavelength of the carbon dioxide laser light fluctuates irregularly, and it is thought that the fluctuation may cause unevenness. Therefore, when the oscillation spectrum characteristics of the carbon dioxide laser were measured, as will be described later (as shown in FIG. 2 (a)), the laser oscillated with a wide spectrum distribution of wavelengths of 9.1 μm to 11.3 μm, It was also found that the output value (optical power value) of each wavelength was not uniform. Moreover, the oscillation spectrum characteristics are such that the temperature fluctuation of the cooling water (not shown in FIG. 7) of the carbon dioxide laser, the voltage fluctuation of the high voltage power supply to the carbon dioxide laser, the carbon dioxide laser tube (FIG. 7).
(Not shown in the figure), it was found that it fluctuates subtly and from moment to moment due to the degree of vacuum inside. It was estimated that the fact that the oscillation spectrum width is wide, that is, the simultaneous oscillation of multiple wavelengths and the variation of the oscillation wavelength characteristics are the main causes of the unevenness. In other words, the substrate material has wavelength dependency on light absorption, and when the substrate material is irradiated with carbon dioxide laser light whose oscillation wavelength characteristics fluctuate in the wide oscillation spectrum width as described above, the substrate material is cut. It is considered that the cut surface also becomes non-uniform depending on the wavelength and the non-uniformity is further increased when the oscillation spectrum characteristic is changed. Further, when carbon dioxide gas laser beams oscillating at multiple wavelengths are condensed by a condenser lens made of ZnSe material, the condenser lens has an aberration due to wavelength dependence, and it is thought that the cut surface also becomes non-uniform due to this aberration. . Further, the reason why the cutting state changes slightly each time the cutting is performed is considered to be because the device configuration that can always keep the value of the optical power immediately before and during the cutting constant is not realized.

According to the present invention derived from such an idea, the laser device is always oscillated to output a laser beam, and the laser is provided in front of the focusing lens of the optical system in which the focusing lens focuses the laser beam on the surface of the workpiece. By providing a function to block and reflect light with a mirrored shutter to monitor with an optical power meter and a function to open the shutter to irradiate the surface of the processed material, the laser light power immediately before the start of cutting is always kept constant. I have to.

If the laser light reflected by a shutter having a mirror function is monitored by an optical power meter or the like, the optical power up to just before processing can be observed and monitored. Is fed back to the output of the laser device, the optical power immediately before processing can be maintained at a constant value every time processing is performed, and reproducibility and yield can be significantly improved. Further, if an optical spectrum analyzer is connected instead of the optical power meter, it becomes possible to control the optical power and the wavelength so that they are always constant with higher accuracy.

It should be noted that the laser device is provided with a resonator having a grating and laser light of a single wavelength (for example, in the case of a carbon dioxide laser device, as will be described later (as shown in FIG. 2B)), for example, , 10.6 μm) is particularly preferable.

As described above, by selectively outputting only the laser light of a single wavelength, oscillating the laser for a long time immediately before processing, monitoring the optical power, and always processing with the same output optical power, , Reproducible processing can be performed. Further, by combining the shutter opening and closing function of light and the function of reflecting the light by the mirror, it is possible to realize an economical and highly functional device.

Further, by bending the optical path of the laser beam emitted in the horizontal direction by 90 ° by a mirror, the laser beam can be vertically irradiated downward, and XY or XYZ.
The structure of the moving stage in the direction can be simplified and can be moved with high accuracy. Also, since it is difficult for the laser beam to hit the human body, it can be used as a safe device.

Further, by integrally fixing each device component such as the laser device on the vibration-proof table, stable processing can be performed without being influenced by mechanical vibration or impact applied from the outside. It becomes possible.

[0024]

FIG. 1 shows the first embodiment of the carbon dioxide gas laser device for processing of the present invention.

In this device, a carbon dioxide laser irradiation device 102 and a substrate moving mechanism 103 are integrally fixed on a vibration isolation device 101. That is, the carbon dioxide laser irradiation device 102 is fixed to the vibration isolator 101 via the support column 104, and the substrate moving mechanism 103 is fixed to the vibration isolator 101 via the fixing portion 105.

The carbon dioxide laser irradiating device 102 has an external grating (diffraction grating) portion 111 which is an external resonator.
A carbon dioxide gas laser device 121 externally attached, a switch having a shutter 132 having a function of reflecting the output laser beam L ₁ , and a lens 136 through a mirror 135 to collect light on the surface of the substrate 141. An illuminating optical system 131,
An assist gas introduction system for flowing an assist gas G toward the outer periphery of the laser beam L ₃ in the propagation direction of the laser beam, and an optical power meter (or optical spectrum analyzer) for the laser beam L ₅ reflected by the shutter 132 having a mirror function. Thirteen
7 and the system for measurement.

The substrate moving mechanism 103 includes X, Y and Z direction moving mechanisms 143, 144 and 145, a fixed base 142 fixed on the Z direction moving mechanism 145, and the fixed base 1.
Work piece (substrate in this case) fixedly arranged on 42
And 41. The fixed base 142 is provided with a groove 146, and is devised so that the laser light L ₃ diffuses in the groove 146 after penetrating the substrate 141.

The assist gas G is blown to the surface of the processed material 141, the function of keeping the surface of the processed material 141 always clean, the function of cooling the processed part, and the ultrafine amount of the processed material 141 generated during processing. It acts to blow out powder.

Next, in the oscillation spectrum of the laser L ₁ oscillated and output from the carbon dioxide gas laser device 121, in the case of the so-called conventional configuration in which the Brewster window 127 is formed by the internal mirror without the grating portion 111, Since resonance occurs between the internal mirror and the internal mirror 125 mounted on the other side of the carbon dioxide laser tube 122, and the output is output from the output extraction hole 126, as shown in FIG. It oscillates over a wide wavelength range of .1 μm to 11.3 μm, and the optical power oscillating at each wavelength also has a distribution. This wide oscillation spectrum distribution and its optical power distribution adversely affect the cutting of the substrate 141 or the processing of grooves and the like. The carbon dioxide laser 121
Is filled with a mixed gas 123 in which CO ₂ , N ₂ and He are mixed at a ratio of 8:18:74 in the carbon dioxide laser tube 122, and the discharge necessary for causing the population inversion is generated in the carbon dioxide laser tube 122. Electrodes 124a, 124b for
Is provided. Although not shown, the carbon dioxide gas laser tube 122 is a double tube.
The outer circumference of is water-cooled. Further, in order to increase the optical power, a carbon dioxide gas laser tube with a resonator may be connected in series at both ends.

On the other hand, the carbon dioxide gas laser device 121 of the present invention
The oscillation spectrum of the laser beam L ₁ oscillated from the laser beam is output from the above wavelength range by changing the angle θ by rotating the micrometer of the angle adjusting unit 113 that adjusts the angle θ of the grating 112. Since only light of one wavelength (for example, 10.6 μm) can be selectively extracted and output, the oscillation spectrum characteristic as shown in FIG. 2B is obtained. If the substrate 141 is cut with a laser beam having such an oscillation spectrum characteristic of a single wavelength or a groove or the like is processed, there is no unevenness.
A uniform and smooth cut surface or groove surface can be realized.

The carbon dioxide gas laser device 121 is always driven to output the laser beam L ₁ immediately before the processing. Then, the shutter 132 is closed by operating the insertion / removal mechanism 133 of the shutter 132. A mirror is attached to the shutter, and the shutter is provided at an angle of 30 ° to 55 ° (preferably 45 °) with respect to the optical axis of the laser beam, and the laser beam L reflected by the mirror is provided.
₅ is measured by an optical power meter (or optical spectrum analyzer) 137. The laser light L ₅ and L _{1 is} manually or automatically moved back to the drive power source 138 of the carbon dioxide gas laser device 121 and the voltage of the drive power source 138 is adjusted so that the value of the optical power is always constant. The optical power value of can be kept constant. In this way, after the optical power of the laser light is always kept constant, the shutter 132 is opened and the processed material 1 is immediately
41 is irradiated with laser light for processing. In addition, the assist gas G is processed in the flowing state. The shutter 1
In the closed state, the laser beam L ₁ is always applied to 32, and is therefore water-cooled to prevent thermal burnout. The mirror 135 and the grating 112 are also water-cooled.

FIG. 3 shows a second embodiment of a carbon dioxide gas laser device for processing according to the present invention. In this device, a vacuum suction hole 147 is provided in the fixed base 142, and a vacuum suction pump 149 is used to evacuate the vacuum through a vacuum pipe 148 to obtain a substrate 141
Is characterized in that it is vacuum-adsorbed on the fixed base 142.

FIG. 4 shows a third embodiment of the carbon dioxide gas laser device for processing of the present invention. This is a guide in which the laser beams L ₁ and L ₂ output from the carbon dioxide gas laser device 121 are surrounded by a metal tube or box 152. By enclosing this tube or the box 152, dust or oil in the air adheres to the surfaces of the shutter 132, the mirror 152, and the lens 136 to deteriorate the transmittance of laser light, or the above-mentioned adhered matter is affected by laser light. It is possible to prevent burnout and deterioration of the transmittance as well. In addition, safety to the human body can be improved.

FIG. 5 shows a fourth embodiment of the carbon dioxide gas laser device for processing of the present invention. In order to keep the substrate 141 to be processed in the atmosphere of the assist gas G, the entire substrate 141 is covered with an exhaust box 153, and the inside of this box 153 is exhausted by an exhaust device 154. By providing the box 153 and maintaining the surface of the substrate 141 in the assist gas atmosphere, it is possible to prevent oxygen, dust, and organic substances in the air from being taken in, and prevent deterioration of the processed surface and deterioration of strength.

The present invention is not limited to the above embodiment. First, the grating may be a carbon dioxide gas laser device with a built-in grading that is incorporated in the carbon dioxide gas laser device to control the wavelength. As a method for keeping the optical power of the laser light L _{5 at} a constant value, the gas pressure in the carbon dioxide laser tube 123 may be adjusted in addition to the method of adjusting the voltage of the drive power supply circuit 138. Furthermore, the present invention is applicable to gas laser devices other than carbon dioxide gas laser devices.

[0036]

The laser processing method and apparatus of the present invention have the following effects.

(1) Since only laser light of a single wavelength is selectively output, uniform processing can be performed regardless of the material, and the laser power is constantly oscillated for a long time immediately before processing to monitor its optical power. Since processing can be performed with the same output light power, processing can be performed with good reproducibility every time. Thereby, the processing cost can be reduced. In addition, an economical and high-performance device can be realized by using a shutter opening / closing function and a mirror reflecting function together.

(2) Since the laser light reflected by the shutter having the mirror function and taken out can be monitored by the optical power meter, the optical power up to immediately before processing can be observed and monitored. Thereby, the processing can be stably performed.

(3) Since the optical power immediately before processing can be kept at a constant value every time processing is performed, reproducibility and yield can be greatly improved. If an optical spectrum analyzer is connected instead of the optical power meter, it is possible to control the optical power and the wavelength so that they are always constant with higher accuracy.

(4) The processing can be stably performed without being affected by mechanical vibration or impact applied from the outside during the processing.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first processing laser device according to the present invention.

2A is an oscillation spectrum characteristic diagram of a conventional carbon dioxide gas laser device, and FIG. 2B is an oscillation spectrum characteristic diagram of a carbon dioxide gas laser device of the present invention.

FIG. 3 is a configuration diagram of a second processing laser device of the present invention.

FIG. 4 is a configuration diagram of a third processing laser device according to the present invention.

FIG. 5 is a configuration diagram of a fifth processing laser device of the present invention.

FIG. 6 is a plan view of a substrate material for explaining a method of cutting and separating an integrated circuit.

FIG. 7 is a configuration diagram of a glass cutting device that has been previously proposed by the inventor of the present invention by irradiation with carbon dioxide laser light.

FIG. 8 is an explanatory diagram showing an example of substrate cutting by irradiation of carbon dioxide gas laser previously proposed by the present inventor.

[Explanation of symbols]

 103 substrate moving mechanism 111 external grating part 121 carbon dioxide laser device 132 shutter 133 insertion / removal mechanism 134 switch 136 condensing lens 137 optical power meter 141 processed material (substrate)

Claims (11)

[Claims] 1. A mirror function for switching between reflection and transmission of a laser beam on an optical path of the laser beam in a method of processing a workpiece by irradiating the laser beam emitted from a laser device and then irradiating the workpiece. A laser processing method comprising: disposing a shutter having: and controlling switching of blocking and opening of laser light by this shutter. 2. A laser processing method according to claim 1, wherein the laser device is provided with a resonator having a grating capable of selecting a laser beam having a desired wavelength, and a laser beam having a single wavelength is obtained by this resonator. 3. The laser processing method according to claim 1, wherein the laser light reflected by the shutter is monitored. 4. The laser processing method according to claim 3, wherein the output of the laser device is adjusted so that the monitored optical power becomes constant. 5. A laser device for emitting a laser beam, a condenser lens for condensing the laser beam output by the laser device on the surface of a workpiece, the condenser lens and the surface of the workpiece. In a laser processing device having at least a gas introduction mechanism for flowing an assist gas between the laser device and the condensing lens, a mirror function for reflecting and blocking the laser beam or for transmitting and opening the laser beam A laser processing apparatus having a shutter provided with. 6. The laser processing apparatus according to claim 5, wherein the laser apparatus is provided with a resonator having a grating capable of selecting a laser beam having a desired wavelength. 7. The laser processing apparatus according to claim 5, further comprising an optical power meter for monitoring the laser light reflected by the shutter. 8. The laser processing apparatus according to claim 7, wherein the output signal of the optical power meter is fed back to the drive power source of the laser apparatus so that the monitored optical power becomes constant. 9. The laser processing apparatus according to claim 5, wherein a mirror for bending the optical path of the laser beam to 90 ° is provided between the shutter and the condenser lens. 10. A material to be processed is at least in the X direction or Y.
The laser processing apparatus according to claim 5, further comprising an electrically driven moving stage that moves in a direction. 11. A laser device and a shutter, a mirror, a condenser lens, a gas introduction mechanism or a moving stage are integrally fixed on a vibration-proof table having a vibration-proof function. The laser processing apparatus according to any one of claims.