JP2013126689A - Laser processing apparatus, and laser processing method, and method for manufacturing substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a configuration that can more accurately adjust a position to which a laser beam is applied even if the strength of the laser beam to be applied to a workpiece 11 varies.SOLUTION: A laser beam whose light path is changed by a light modulation device 7 for changing the polarization direction of a penetrating light and a first polarizer 6 is reflected according to the polarization of a laser beam by a second polarizer 61, and is incident into a position sensor 81. This allows the strength of the laser beam incident into the position sensor 81 to be within a strength range set by the position sensor even when the strength of the laser beam varies. In addition, the position sensor 81 can be placed at a position closer to the workpiece 11, thereby limiting the influence of air shimmering, or the like, to the minimum. As a result, a position to which the laser beam is applied is more accurately adjusted.

Description

  The present invention relates to a laser processing apparatus that processes a workpiece using laser light, a laser processing method, and a substrate manufacturing method including a laser processing step.

  Processing using laser light such as drilling, cutting, and welding is used in various fields such as machinery, electronics, and semiconductors. As a laser processing apparatus that performs these processes, a technique has been proposed in which laser light output from a laser oscillator is controlled using an electro-optic element and a polarization beam splitter to perform processing and stop processing (Patent Document 1).

  In the case of the technique described in Patent Document 1, first, the direction of the linearly polarized light of the laser light is changed by an electro-optic element, and P waves and S waves are selectively emitted. Thereafter, the polarization beam splitter branches the optical path into two optical paths, mainly an optical path from which the P wave is emitted and an optical path from which the S wave is mainly emitted. Accordingly, by selecting the P wave or S wave with the electro-optic element, the optical path after the polarization beam splitter is determined, and switching between processing and processing stop is performed.

  Moreover, such a laser processing apparatus irradiates a workpiece with laser light, and the irradiated part is processed. Therefore, the irradiation position accuracy on the workpiece is greatly related to the processing quality, and is an important factor that determines the processing position accuracy. However, the optical axis of the laser light emitted from the laser oscillator is shifted due to the influence of the temperature change of the laser oscillator and the fluctuation of the air in the optical path. For this reason, unless any countermeasure is taken, the irradiation position accuracy decreases. As a countermeasure against such an optical axis deviation of the laser beam, a technique for automatically adjusting the optical axis so that the irradiation position of the laser beam does not deviate from the target point has been proposed (Patent Document 2).

  In the case of the technique described in Patent Document 2, a part of the laser light is branched by a transmission mirror, and the branched laser light is made incident on the position sensor. Then, the optical axis is automatically adjusted by controlling the movable mirror based on the output signal of the position sensor.

JP 2004-291010 A JP 2002-133730 A

  In the case of the technique described in Patent Document 2 described above, laser light is incident on the position sensor using a certain partially transmissive mirror having a reflectance and a transmittance. For this reason, when the intensity of the laser light changes, the intensity of the laser light incident on the position sensor also changes in accordance with the change in the intensity of the laser light.

  In order to detect the laser beam, the intensity of the laser beam needs to be within the intensity range defined by the position sensor. However, if the variation range of the intensity of the laser beam increases, the laser beam deviates from the intensity range defined by the position sensor. The position cannot be detected accurately.

  Therefore, when such a technique is applied to the laser processing apparatus described in Patent Document 1, a position sensor is arranged in a portion where the intensity of the laser light changes during processing and non-processing, that is, in the optical path after the polarization beam splitter. Can not. On the other hand, a position sensor can be arranged in a portion where the intensity of the laser beam does not change during processing and non-processing, that is, before the polarization beam splitter. However, it is impossible to adjust the optical axis deviation due to air fluctuations in the optical path after the polarizing beam splitter. In other words, it is difficult to accurately adjust the misalignment of the optical axis (adjustment of the irradiation position of the laser beam) due to the influence of air fluctuations in the optical path after the polarizing beam splitter.

  In laser processing, even within the same workpiece, the laser beam intensity may be changed greatly. For example, there are cases where there are different kinds of materials in part, or when it is desired to greatly change the processing form. In such a case, if the sensitivity of the position sensor is adjusted in accordance with the higher intensity of the laser beam, the laser beam with the lower intensity is insufficiently input and the position cannot be detected. Further, if the adjustment is made in accordance with the smaller intensity, the input with the larger intensity becomes excessive, and the position cannot be detected.

  In view of such circumstances, the present invention has been invented to realize a structure that can adjust the irradiation position of laser light more accurately even if the intensity of the laser light irradiated to the workpiece changes. .

  The present invention relates to a laser oscillator, a position sensor that detects the position of the laser light emitted by the laser oscillator, and a position that changes the irradiation position of the laser light on the workpiece based on the detection result of the position sensor. A change member, a polarization direction switching member that switches a polarization direction of laser light emitted by the laser oscillator between a first polarization direction and a second polarization direction, a path of laser light, the polarization direction switching member, and the A first branching member and a second branching member that are arranged between the position sensor and branch the laser beam in accordance with the polarization direction switched by the polarization direction switching member, respectively. The branch member is configured so that the laser beam is mainly in the first branch optical path when the polarization direction switched by the polarization direction switching member is the first polarization direction, and the polarization direction is When the polarization direction is two, the laser beam is branched mainly into the second branch optical path, and a part thereof is split into the first branch optical path. The second branch member is located in the first branch optical path, and is a laser. When the polarization direction is the first polarization direction, the light is mainly on the workpiece side, partly on the position sensor side, and mainly when the polarization direction is the second polarization direction. The laser processing apparatus is characterized by branching to the sensor side.

  Furthermore, when processing with the intensity of the laser beam changed during processing, a fluorescent plate is disposed upstream of the position sensor, and the laser beam strikes between the second branch member and the position sensor downstream of the fluorescent plate. In this laser processing apparatus, a filter that transmits the fluorescent light emitted from the fluorescent plate but blocks the wavelength of the used laser light is provided.

  According to the present invention, since the laser beam detected by the position sensor is branched by the first branch member and the second branch member, regardless of the intensity of the laser beam irradiated to the workpiece, the position sensor It is possible to fit within the specified strength range. In addition, since the position sensor detects the laser light after the first branch member and the second branch member, the influence of air fluctuation and the like can be suppressed. As a result, the laser beam irradiation position can be adjusted more accurately.

  In addition, a fluorescent plate is disposed upstream of the position sensor, and a filter that blocks the wavelength of the laser light is disposed between the second branching member and the position sensor downstream of the fluorescent plate, so that the laser beam is processed during processing. The position can be detected by the position sensor even if the intensity of the sensor is changed.

1 is a schematic configuration diagram of a laser processing apparatus according to a first embodiment of the present invention. The flowchart of the laser processing process which concerns on 1st Embodiment. The schematic block diagram of the laser processing apparatus which concerns on the 2nd Embodiment of this invention. The flowchart of the laser processing process which concerns on 2nd Embodiment. Schematic configuration diagram of a laser processing apparatus according to a third embodiment of the present invention. The flowchart of the laser processing process which concerns on 3rd Embodiment. Sectional drawing which shows a part of inkjet head.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the present embodiment, a laser processing apparatus will be described in which laser light is focused on the workpiece 11 serving as a material of the substrate and processing is performed on a part of the workpiece 11. In addition, the board | substrate manufactured by this embodiment is a semiconductor material board | substrate, a glass substrate, a piezoelectric material board | substrate, etc., for example.

The laser processing apparatus of this embodiment includes a laser oscillator 4, a light modulation element 7, a first polarizer 6, a second polarizer 61, a position sensor 81, a movable mirror 91, a condensing lens 31, a beam damper 10, a stage 51, and a control. It has a device 8. Of these, the laser oscillator 4 uses a YAG laser, a CO ₂ laser, an excimer laser, or the like. From the laser oscillator 4, linearly polarized laser light 21 is oscillated toward the light modulation element 7 described below.

  The light modulation element 7 is, for example, an electro-optic element (EOM) as a polarization direction switching member that switches the polarization direction of the laser light 21 irradiated by the laser oscillator 4. In this light modulation element 7, the polarization direction of the laser light 21 is a P wave (P polarization) which is the second polarization direction or the first polarization direction in accordance with a control signal from the control device 8 which will be described later. Conversion into S-wave (S-polarized) laser light 22 is performed. The light modulation element 7 can respond faster than the pulse repetition frequency of the laser oscillator 4, and can change the polarization direction of the laser light 21 for each pulse in accordance with a control signal from the control device 8.

  The first polarizer 6 and the second polarizer 61 are arranged between the light modulation element 7 and a position sensor 81 described later with respect to the path of the laser light. Each of the first branching member and the second branching member branches the laser light according to the polarization direction switched by the light modulation element 7. The first polarizer 6 and the second polarizer 61 are, for example, a cube-type polarization beam splitter, a plate-type polarization beam splitter, or the like.

  Further, the first polarizer and the second polarizer have the same polarization extinction ratio characteristic, which is a ratio of mainly splitting the incident laser light according to the polarization direction. In the case of the present embodiment, the first polarizer and the second polarizer have a P-polarized light transmittance of about 99%, a reflectance of about 1%, an S-polarized light transmittance of about 1%, and a reflectance of about 99%, respectively. Laser light is reflected and transmitted with optical characteristics.

  The first polarizer 6 that is the first branching member branches the laser light according to the polarization direction of the laser light 22. In other words, the laser beam 23 transmitted through the first polarizer 6 and the laser beam 24 reflected by the first polarizer are emitted.

  That is, the first polarizer 6 cannot branch all the laser beams, and it is inevitable that a part of the first polarizer 6 leaks. In the present embodiment, when the polarization direction switched by the light modulation element 7 is an S wave having the first polarization direction, the laser light is mainly (99%) on the movable mirror 91 side, which will be described later, which is the first branch optical path. Is branched (reflected). Further, a part (1%) of light leaks (transmits) to the beam damper 10 described later. On the other hand, in the case of a P wave whose polarization direction is the second polarization direction, the laser light is branched (transmitted) mainly to the beam damper 10 side which is the second branch optical path (99%), and partially (1%). Light leaks (reflects) to the movable mirror 91 side.

  The second polarizer 61, which is the second branch member, is positioned in the first branch optical path, and the laser beam 24 is incident thereon. Then, the laser beam is branched according to the polarization direction of the laser beam 22. In other words, the laser beam 25 transmitted through the second polarizer 61 and the laser beam 26 reflected by the second polarizer 61 are emitted.

  That is, as with the first polarizer 6, the second polarizer 61 cannot branch all of the laser light, and it is inevitable that some of the laser light leaks. In this embodiment, when the polarization direction switched by the light modulation element 7 is an S wave, the laser light is branched (reflected) mainly to the workpiece side (99%), and a part (1%) of the light is It leaks (transmits) to the position sensor 81 side. On the other hand, when the polarization direction is a P wave, the laser beam is branched (transmitted) mainly to the (99%) position sensor side, and a part (1%) of the light leaks (reflects) to the workpiece 11 side. .

  The position sensor 81 is a position sensor that detects the position of the laser light emitted by the laser oscillator 4, and is composed of, for example, a PSD, an ND filter, or a lens. Then, a positional variation and an angular variation of the laser light 25 transmitted through the second polarizer 61 are detected. The detected output signal is sent to the control device 8, and signal processing such as integration is performed to obtain position data of the laser beam. The position sensor 81 can detect, for example, an intensity range of ± 10% with respect to the set intensity of the laser beam.

  The movable mirror 91 is a position changing member that changes the irradiation position of the laser beam to the workpiece 11 based on the detection result of the position sensor 81. In the present embodiment, one movable mirror 91 is provided. When one movable mirror is provided, not only the angle but also the position of the movable mirror may be changed. The movable mirror 91 is, for example, a dielectric multilayer mirror or a metal deposition mirror, and may change the position and angle by a piezo element or a stepping motor to change the optical path of the reflected light. In this embodiment, a case where one movable mirror 91 is provided will be described, but a plurality of movable mirrors 91 may be arranged. By changing the angle, the irradiation position of the laser beam can be changed and adjusted.

  In addition to the movable mirror, the position changing member may change the refractive index of light. That is, the optical path is changed by changing the refractive index, and the irradiation position of the laser beam is changed and adjusted. Such a refractive index can be changed by, for example, an electro-optic element (refractive index modulation) that is composed of an electrode and an electro-optic material (dielectric material), and changes the refractive index of light passing therethrough according to the strength of an applied electric field. Element) or the like. Alternatively, the lens may be moved. That is, the optical path can be changed by moving the lens and changing the position where the light is transmitted.

  The condensing lens 31 uses an optical system that condenses laser light into a minute spot or an optical system having a scanning mechanism, for example, an optical system that combines a galvano scanner and an fθ lens. The beam damper 10 absorbs one of the laser beams branched by the first polarizer 6. The stage 51 moves the workpiece 11 freely in the XYZ directions.

  The control device 8 controls the laser oscillator 4, the stage 51, the light modulation element 7, the position sensor 81, and the movable mirror 91. The control device 8 controls the strength of the electric field in the case of an optical system having an electro-optic element (refractive index modulation element) that changes the refractive index of light passing therethrough according to the strength of the electric field that can change the refractive index. Also do. Further, the control device 8 also controls the scanning mechanism of the condensing lens 31 when the condensing lens 31 is an optical system having a scanning mechanism.

  Next, the laser processing step of this embodiment will be described with reference to FIG. The laser beam 21 oscillates at a certain repetition frequency from the laser oscillator 4. Since the laser light 21 is pulse-oscillated at a constant repetition frequency, the excitation time does not vary, and the laser light output stability is superior to the case where the repetition frequency is varied. The direction of polarization of the laser beam 21 can be changed by the light modulation element 7 in accordance with a control signal from the control device 8 for each pulse, and the laser beam 22 after passing through the P-polarization or S-polarization light modulation element 7. Is selectively output (polarization direction switching step, S11).

  Here, when processing the workpiece 11, the laser beam is irradiated on the workpiece 11, and when the processing on the workpiece 11 is stopped (not processed), the laser beam is irradiated on the beam damper 10. Therefore, when processing the workpiece 11, the light modulation element 7 is controlled so that the workpiece 11 is irradiated with laser light. In the case of the present embodiment, if the light modulation element 7 changes to the S wave (Y in S12), the laser beam is branched mainly to the movable mirror 91 side by the first polarizer 6 (first branching step, S13).

  In the case of the present embodiment, an energy loss of about 1% occurs when passing through the light modulation element 7, so that the intensity of the laser light 22 after passing through the light modulation element 7 is about 99% of the intensity of the laser light 21. . Then, the laser light 22 that has passed through the light modulation element 7 is then guided to the first polarizer 6.

  As described above, the first polarizer 6 reflects laser light with optical characteristics of P-polarized light transmittance of about 99%, reflectance of about 1%, S-polarized light transmittance of about 1%, and reflectance of about 99%. Make it transparent. For this reason, the workpiece 11 or the beam damper 10 is mainly irradiated with the laser beam after passing through the first polarizer 6 by the control of the polarization direction by the light modulation element 7 and the first polarizer 6. Or can be determined in units of one pulse.

  When the workpiece 11 is processed, the laser beam that passes through the light modulation element 7 is selected to be an S wave as described above. As a result, approximately 1% of the laser beam 22 is transmitted through the first polarizer 6 and is irradiated onto the beam damper 10. Further, about 99% of the laser beam 22 is reflected by the first polarizer 6, reflected by the movable mirror 91, and guided to the second polarizer 61.

  As described above, the second polarizer 61 is the same as the first polarizer, and has a P-polarized light transmittance of about 99%, a reflectance of about 1%, an S-polarized light transmittance of about 1%, and a reflectance of about 99%. Laser light is reflected and transmitted with optical characteristics (second branching step, S14). At this time, since the laser beam guided to the second polarizer 61 is S-polarized light, the laser beam 25 transmitted through the second polarizer 61 is about 1% of the intensity of the laser beam 24 guided to the second polarizer 61. The laser beam 25 having this intensity enters the position sensor 81.

  In other words, the intensity of the laser beam 25 is about 0.98% (= 99% × 99% × 1%) of the intensity of the laser beam 21. The position sensor 81 is set in advance so as to be able to detect the position variation and the angle variation of the laser beam that is about 0.98% of the intensity of the laser beam 21 by using an ND filter or a lens. The position sensor 81 to which the laser beam 25 having such an intensity is incident detects a position variation or an angle variation of the laser beam 25 (position detection step, S15).

  Then, the movable mirror 91 is moved by the control device 8 so that the position of the laser beam 25 in the position sensor 81 becomes a predetermined position. That is, based on the detection result by the position sensor 81 in the position detection step, the irradiation position of the laser beam to the workpiece 11 is changed (position change step, S16). Thereby, the position of the laser beam being processed can be automatically adjusted, and the irradiation position accuracy of the laser beam to the workpiece 11 is improved.

  On the other hand, the laser beam 26 reflected by the second polarizer 61 has an intensity of about 99% of the laser beam guided to the second polarizer 61. In other words, the intensity of the laser beam 26 reflected by the second polarizer 61 is approximately 97.03% (= 99% × 99% × 99%) of the intensity of the laser beam 21. The laser beam 26 reflected by the second polarizer 61 is irradiated to the workpiece 11 through the condenser lens 31, and the workpiece 11 is processed (S17).

  Next, a description will be given of a case where the machining is stopped (non-machining) when the machining shape of the workpiece 11 becomes a desired shape or the workpiece 11 is moved to the next machining point. When the processing is stopped, the laser light transmitted through the light modulation element 7 is selected to be P-polarized light (N in S11 and S12).

  As a result, about 99% of the laser beam 22 is transmitted through the first polarizer 6 and irradiated to the beam damper 10 (first branching step, S18). Further, about 1% of the laser beam 22 is reflected by the first polarizer 6, reflected by the movable mirror 91, and guided to the second polarizer 61.

  Since the laser beam guided to the second polarizer 61 is P-polarized light, the laser beam 25 transmitted through the second polarizer 61 has about 99% of the intensity of the laser beam guided to the second polarizer 61 to be the position sensor 81. (Second branching step, S19). In other words, using the laser beam 21 as a reference, the intensity of the laser beam 25 transmitted through the second polarizer 61 is about 0.98% (= 99% × 1% × 99%) of the intensity of the laser beam 21.

  As described above, the position sensor 81 is set in advance so as to be able to detect a position variation and an angle variation of the laser beam that is about 0.98% of the intensity of the laser beam 21 by an optical system such as an ND filter and a lens. Therefore, the position sensor 81 detects the position variation and the angle variation of the laser light 25 during the machining stop as in the machining (position detection step, S20).

  Then, the movable mirror 91 can be moved by the control device 8 so that the position of the laser beam 25 in the position sensor 81 becomes a predetermined position (position changing step, S21). As a result, the irradiation position can be controlled with high accuracy even while the workpiece 11 is stopped, so that it is possible to perform processing with high positional accuracy from the beginning when switching from stopping to processing.

  The laser beam 26 reflected by the second polarizer 61 has an intensity of about 1% of the laser beam guided to the second polarizer 61. In other words, with reference to the laser beam 21, the intensity of the laser beam 26 reflected by the second polarizer 61 is about 0.01% (= 99% × 1% × 1%) of the intensity of the laser beam 21. The laser beam 26 reflected by the second polarizer 61 is irradiated to the workpiece 11 through the condenser lens 31.

  Here, a condition that the processing threshold of the workpiece 11 is not exceeded even when approximately 0.01% of the intensity of the laser beam 21 is irradiated by the oscillation condition of the laser oscillator 4 or the condenser lens 31 or the like is previously set. Set it. Thereby, even if the laser beam 26 reflected by the second polarizer is irradiated to the workpiece 11 through the condenser lens 31, the workpiece 11 is not processed (S22). This processing, processing stop, and movement of the workpiece 11 by the stage 51 are performed until the desired processing is completed on the workpiece 11, and the processing ends.

  In the case of the present embodiment, the laser beam detected by the position sensor 81 is branched by the first polarizer 6 and the second polarizer 61, so that the position is determined regardless of the intensity of the laser beam irradiated to the workpiece 11. It can be within the intensity range defined by the sensor 81. In the present embodiment, the first polarizer 6 and the second polarizer 61 have the same polarization extinction ratio characteristic. For this reason, the laser beam incident on the position sensor 81 is emitted when the workpiece 11 is irradiated with a high-intensity laser beam during processing and when the workpiece 11 is irradiated with a low-intensity laser beam during non-processing. Are the same strength. For this reason, the detection accuracy by the position sensor 81 can be maintained regardless of whether it is processed or not.

  Further, since the position sensor 81 detects the laser light after the first polarizer 6 and the second polarizer 61, the influence of air fluctuations can be suppressed. That is, in the case of this embodiment, the position sensor 81 can be disposed at a position close to the workpiece 11, and the influence of air fluctuations can be minimized.

  In the case of the present embodiment, the laser light detected by the position sensor 81 can be within the intensity range determined by the position sensor 81 during processing and during non-processing, and the detection by the position sensor 81 is processed. It can be performed at a position close to the object 11. As a result, the laser beam irradiation position can be changed and adjusted more accurately.

  Note that the position of the movable mirror 91 can be arranged at another position as long as it is upstream of the position sensor 81 with respect to the path of the laser beam. Further, the polarization extinction ratio characteristics of the first polarizer 6 and the second polarizer 61 may not be the same. However, in this case, the combination is such that the laser light incident on the position sensor 81 falls within the intensity range of the position sensor 81 during processing and during non-processing. Further, the relationship between the P wave and the S wave may be reversed.

<Second Embodiment>
A second embodiment of the present invention will be described with reference to FIGS. In the case of the first embodiment described above, the P wave branched by the first polarizer 6 and the light leaked from the first polarizer 6 among the laser light switched to the S wave are absorbed by the beam damper 10. I did it. On the other hand, in the case of the present embodiment, such light is reflected by the mirror 9 and irradiated to another workpiece 12. For this reason, the description overlapping with the first embodiment will be omitted or simplified, and the following description will be focused on the parts different from the first embodiment.

  In the case of the present embodiment, as described above, the mirror 9 that reflects the laser beam branched to the second branch optical path by the first polarizer 6 is provided. The mirror 9 is, for example, a dielectric multilayer film mirror or a metal vapor deposition mirror, and uses it to reflect the laser light and change the direction. Further, the laser beam controlled by the control device 8 and reflected by the mirror 9 is irradiated to the workpiece 12 through the movable mirror 92, the third polarizer 62 corresponding to the second branch member, and the condenser lens 32. To do. Then, when the workpiece 11 is not processed, another workpiece 12 is processed.

  That is, when laser processing is performed on the workpiece 11, the laser light is switched to the S wave by the light modulation element 7, and the laser light is guided mainly to the workpiece 11 side by the first polarizer 6. Further, light leaking from the first polarizer 6 is reflected by the mirror 9 and guided to another workpiece 12. On the other hand, when laser processing of another workpiece 12 is performed without performing laser processing of the workpiece 11, the laser light is switched to the P wave by the light modulation element 7, and the first polarizer 6 mainly performs the mirror 9. The laser beam is guided to. This laser beam is reflected by the mirror 9 and guided to another workpiece 12.

  In any case, the laser beam 27 branched by the third polarizer 62 is incident on the position sensor 82, and the control device 8 that receives the output signal of the position sensor 82 applies the other mirror 12 to another workpiece 12. Change and adjust the irradiation position of the laser beam.

  Here, similarly to the workpiece 11, the other workpiece 12 is a material for the substrate. The workpiece 11 and the workpiece 12 may be the same member. That is, you may make it process each different part of the same workpiece.

  The movable mirror 92 is the same as the movable mirror 91, the third polarizer 62 is the same as the second polarizer 61, the position sensor 82 is the position sensor 81, and the condenser lens 32 is the same as the condenser lens 31. The stage 52 is the same as the stage 51. However, when the workpiece 11 and the workpiece 12 are the same member, the stage 52 and the stage 51 are also the same. The control device 8 also controls the movable mirror 92 and the stage 52.

  Further, the third polarizer 62 branches into a laser beam 27 reflected by the third polarizer 62 and a laser beam 28 transmitted through the third polarizer 62 according to the polarization direction of the laser beam 22. The position sensor 82 is constituted by an optical system such as a PSD, an ND filter, or a lens, for example, and detects a position variation or an angle variation of the laser light 27 reflected by the third polarizer 62.

  In the case of the present embodiment, the position sensor 81 uses the transmitted light of the second polarizer 61 to detect position variation and angle variation, while the position sensor 82 uses the reflected light of the third polarizer 62. To detect. The position sensors 81 and 82 can detect, for example, an intensity range of ± 10% with respect to the set intensity of the laser beam.

  Next, the laser processing process of this embodiment is demonstrated, referring FIG. The laser beam 21 oscillates at a certain repetition frequency from the laser oscillator 4. The direction of polarization of the laser light 21 can be changed by the light modulation element 7 according to a control signal from the control device 8 for each pulse, and the laser light 22 after passing through the light modulation element of P polarization or S polarization is selected. (Polarization direction switching step, S31).

  Since energy loss occurs about 1% when passing through the light modulation element 7, the intensity of the laser light 22 after passing through the light modulation element 7 is about 99% of the intensity of the laser light 21. The laser beam 22 that has passed through the light modulation element 7 is then guided to the first polarizer 6. The first polarizer 6 is a polarizing beam splitter that reflects and transmits laser light with optical properties of P-polarized light transmittance of about 99%, reflectance of about 1%, S-polarized light transmittance of about 1%, and reflectance of about 99%. Let Therefore, by controlling the direction of polarization by the light modulation element 7 and the first polarizer 6, the laser beam after passing through the first polarizer 6 is mainly irradiated to the workpiece 11 or to another workpiece 12. Irradiation can be determined in units of one pulse.

  When the workpiece 11 is processed, the laser beam that passes through the light modulation element 7 is selected to be S-polarized light (Y in S32). As a result, about 99% of the laser beam 22 is reflected by the first polarizer 6, reflected by the movable mirror 91, and guided to the second polarizer 61 (first branching step, S33).

  The second polarizer 61 is a polarizing beam splitter that reflects and transmits laser light with optical properties of P-polarized light transmittance of about 99%, reflectance of about 1%, S-polarized light transmittance of about 1%, and reflectance of about 99%. (Second branching step, S34). At this time, since the laser beam guided to the second polarizer 61 is S-polarized light, the laser beam 25 transmitted through the second polarizer 61 is located at about 1% of the intensity of the laser beam guided to the second polarizer 61. Incident on the sensor 81.

  In other words, the intensity of the laser beam 25 is about 0.98% (= 99% × 99% × 1%) of the intensity of the laser beam 21. The position sensor 81 is set in advance so as to be able to detect a position variation and an angle variation of the laser beam that is about 0.98% of the intensity of the laser beam 21 by an optical system such as an ND filter and a lens. The position sensor 81 to which the laser beam 25 having such an intensity is incident detects a position variation or an angle variation of the laser beam 25 (position detection step, S35).

  Then, the movable mirror 91 is moved by the control device 8 so that the position of the laser beam 25 in the position sensor 81 becomes a predetermined position. That is, based on the detection result by the position sensor 81 in the position detection process, the irradiation position of the laser beam to the workpiece 11 is changed (position change process, S36). Thereby, the position of the laser beam being processed can be automatically adjusted, and the irradiation position accuracy of the laser beam to the workpiece 11 is improved.

  On the other hand, the laser beam 26 reflected by the second polarizer 61 has an intensity of about 99% of the laser beam guided to the second polarizer 61. In other words, the intensity of the laser beam 26 reflected by the second polarizer 61 is approximately 97.03% (= 99% × 99% × 99%) of the intensity of the laser beam 21. The laser beam 26 reflected by the second polarizer 61 is irradiated to the workpiece 11 through the condenser lens 31, and the workpiece 11 is processed (S37).

  Further, about 1% of the laser beam 22 is transmitted through the first polarizer 6, reflected by the mirror 9 and the movable mirror 92, and guided to the third polarizer 62. Since the laser beam guided to the third polarizer 62 is S-polarized light, the laser beam 27 reflected by the third polarizer reflects about 99% of the intensity of the laser beam guided to the third polarizer 62, It enters the sensor 82.

  In other words, the intensity of the laser beam 27 is about 0.98% (= 99% × 1% × 99%) of the intensity of the laser beam 21. The position sensor 82 is set in advance so as to be able to detect a position variation and an angle variation of the laser beam that is about 0.98% of the intensity of the laser beam 21 by an optical system such as an ND filter and a lens. Therefore, the position sensor 82 can detect the position variation and the angle variation of the laser beam 27 and can move the movable mirror 92 by the control device 8 so that the position of the laser beam 27 in the position sensor 82 becomes a predetermined position. Thereby, the irradiation position accuracy of the laser beam to the workpiece 12 during non-processing is improved.

  The laser light 28 transmitted through the third polarizer 62 has an intensity of about 1% of the laser light guided to the third polarizer 62. In other words, using the laser beam 21 as a reference, the intensity of the laser beam 28 that has passed through the third polarizer is approximately 0.01% (= 99% × 1% × 1%) of the intensity of the laser beam 21. The laser beam 28 that has passed through the third polarizer 62 is irradiated to the workpiece 12 through the condenser lens 32. Here, a condition that the processing threshold of the workpiece 12 is not exceeded even when about 0.01% of the intensity of the laser beam 21 is irradiated by the oscillation condition of the laser oscillator 4 or the condensing lens 32 or the like is previously set. Set it. Thereby, even if the laser beam 28 reflected by the third polarizer 63 is irradiated to the workpiece 12 through the condenser lens 32, the workpiece 12 is not processed.

  Next, when processing the workpiece 12, the laser beam transmitted through the light modulation element 7 is selected to be P-polarized light (N in S31 and S32). As a result, about 99% of the laser beam 22 is transmitted through the first polarizer 6, reflected by the mirror 9 and the movable mirror 92, and guided to the third polarizer 62 (first branching step, S38).

  The third polarizer 62 is a polarizing beam splitter that reflects and transmits laser light with optical properties of approximately 99% P-polarized light transmittance, approximately 1% reflectance, approximately 1% S-polarized light transmittance, and approximately 99% reflectance. Let At this time, since the laser beam guided to the third polarizer 62 is P-polarized light, the laser beam 27 reflected by the third polarizer 62 is positioned at about 1% of the intensity of the laser beam guided to the third polarizer 62. The light enters the sensor 82 (third branching step, S39). In other words, using the laser beam 21 as a reference, the intensity of the laser beam 27 reflected by the third polarizer 62 is about 0.98% (= 99% × 99% × 1%) of the intensity of the laser beam 21.

  As described above, the position sensor 82 is set in advance so as to be able to detect the position variation and the angle variation of the laser beam that is about 0.98% of the intensity of the laser beam 21. The position sensor 82 detects a position variation or an angle variation of the laser light 27 reflected by the third polarizer 62 (another position detection step, S40).

  Then, the movable mirror 92 is moved by the control device 8 so that the position of the laser beam 27 reflected by the third polarizer 62 in the position sensor 82 becomes a predetermined position (another position changing step, S41). Thereby, the position of the laser beam being processed can be automatically adjusted, and the irradiation position accuracy of the laser beam to the workpiece 12 is improved.

  The laser light 28 transmitted through the third polarizer 62 has an intensity of about 99% of the laser light guided to the third polarizer 62. In other words, using the laser beam 21 as a reference, the intensity of the laser beam 28 that has passed through the third polarizer 62 is approximately 97.03% (= 99% × 99% × 99%) of the intensity of the laser beam 21. The laser beam 28 that has passed through the third polarizer 62 is irradiated to the workpiece 12 through the condenser lens 32, and the workpiece 12 is processed (S42).

  In addition, about 1% of the laser beam 22 is reflected by the first polarizer 6, reflected by the movable mirror 91, and guided to the second polarizer 61. Since the laser beam guided to the second polarizer 61 is P-polarized light, the laser beam 25 transmitted through the second polarizer 61 has about 99% of the intensity of the laser beam guided to the second polarizer 61 to be the position sensor 81. Is incident on. In other words, the intensity of the laser beam 25 is about 0.98% (= 99% × 1% × 99%) of the intensity of the laser beam 21.

  As described above, the position sensor 81 is set in advance so as to detect the position variation and angle variation of the laser beam that is about 0.98% of the intensity of the laser beam 21. Therefore, the position sensor 81 can detect the position variation and the angle variation of the laser beam 25 and can move the movable mirror 91 by the control device 8 so that the position of the laser beam 25 in the position sensor 81 becomes a predetermined position. Thereby, the irradiation position accuracy of the laser beam to the workpiece 11 during non-processing is improved. As described above, since the irradiation position can be controlled with high accuracy even when the workpiece 11 is not being processed, the processing can be performed with high positional accuracy from the beginning.

  The laser beam 26 reflected by the second polarizer 61 has an intensity of about 1% of the laser beam guided to the second polarizer 61. In other words, using the laser beam 21 as a reference, the intensity of the laser beam 26 transmitted through the second polarizer 61 is about 0.01% (= 99% × 1% × 1%) of the intensity of the laser beam 21. The laser beam 26 that has passed through the second polarizer 61 is irradiated to the workpiece 11 through the condenser lens 31.

  Here, a condition that the processing threshold of the workpiece 11 is not exceeded even when approximately 0.01% of the intensity of the laser beam 21 is irradiated by the oscillation condition of the laser oscillator 4 or the condenser lens 31 or the like is previously set. Set it. Thereby, even if the laser beam 26 reflected by the second polarizer 61 is irradiated to the workpiece 11 through the condenser lens 31, the workpiece 11 is not processed.

  Switching between the processing of the workpiece 11 and the processing of the workpiece 12 and the movement of the workpiece 11 and the workpiece 12 by the stage 51 and the stage 52 are performed on the workpiece 11 and the workpiece 12 as desired. Is completed until the processing is completed.

  In the case of the present embodiment, by performing such switching, as in the first embodiment, the intensity range defined by the position sensors 81 and 82 regardless of the intensity of the laser light irradiated on the workpieces 11 and 12. Can fit in. Further, detection by the position sensors 81 and 82 can be performed at positions close to the workpieces 11 and 12, respectively. As a result, the laser beam irradiation position can be adjusted more accurately.

  In the above description, the workpiece is mounted for each stage. However, a plurality of workpieces can be mounted on one stage. Moreover, when processing by switching, the process which switches the processing point on the same workpiece instead of switching the workpiece to be irradiated is also possible.

  Further, between the laser oscillator 4 and the light modulation element 7, for example, a mechanical shutter, a shutter mechanism including an optical modulation element, a polarizer, a damper, or the like is configured, and both the workpiece 11 and the workpiece 12 are provided. It is also possible to adopt a configuration without laser irradiation. Other configurations and operations are the same as those in the first embodiment.

<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an example of processing while changing the intensity of laser light during processing will be described. In addition, the board | substrate manufactured in this embodiment is a semiconductor material board | substrate, a glass substrate, a piezoelectric material board | substrate, a metal substrate, a resin substrate etc., and the board | substrate which a part of board | substrate consists of a different material is also contained.

The laser processing apparatus of this embodiment includes a laser oscillator 104, a light modulation element 107, a first polarizer 106, a second polarizer 161, a fluorescent plate 171, a filter 172, a position sensor 181, movable mirrors 191, 192, and a beam damper 110. Have. Furthermore, a scanning mechanism 141, a condensing lens 131, a stage 151, and a control device 108 are included. Among these, the laser oscillator 104 uses a YAG laser, a CO ₂ laser, an excimer laser, or the like. From the laser oscillator 104, linearly polarized laser light 121 is emitted toward the light modulation element 107.

  The light modulation element 107 is, for example, an electro-optic element (EOM) as a polarization direction switching member that switches the polarization direction of the laser light 121 emitted from the laser oscillator 104. In response to a control signal from the control device 108, the light modulation element 107 changes the polarization direction of the laser light 121 to the S wave (S polarization) that is the first polarization direction or the P wave that is the second polarization direction. Conversion into (P-polarized) laser light 122. The light modulation element 107 can respond faster than the repetition frequency of the laser oscillator 104, and the direction of polarization of the laser light 121 can be changed for each pulse in accordance with a control signal from the control device.

  The first polarizer 106 and the second polarizer 161 are disposed between the light modulation element 107 and a position sensor 181 described later with respect to the path of the laser light. Each of the first branching member and the second branching member branches the laser light according to the polarization direction switched by the light modulation element 107. Such first polarizer 106 and second polarizer 161 are, for example, a cube-type polarization beam splitter, a plate-type polarization beam splitter, or the like.

  Further, the first polarizer and the second polarizer have the same polarization extinction ratio characteristic, which is a ratio of mainly splitting the incident laser light according to the polarization direction. In the case of the present embodiment, the first polarizer and the second polarizer have a P-polarized light transmittance of about 99%, a reflectance of about 1%, an S-polarized light transmittance of about 1%, and a reflectance of about 99%, respectively. Laser light is reflected and transmitted with optical characteristics.

  The first polarizer 106 that is the first branch member branches the laser light in accordance with the polarization direction of the laser light 122. In other words, the laser beam 123 that has passed through the first polarizer 106 and the laser beam 124 that has been reflected by the first polarizer are emitted.

  That is, the first polarizer 106 cannot branch all of the laser light, and it is inevitable that a part of it leaks. In the present embodiment, when the polarization direction switched by the light modulation element 107 is an S wave having the first polarization direction, the laser light is mainly (99%) on the movable mirror 191 side, which will be described later, which is the first branch optical path. Is branched (reflected). Further, a part (1%) of light leaks (transmits) to the beam damper 110 described later. On the other hand, in the case of the P wave whose polarization direction is the second polarization direction, the laser beam is branched (transmitted) mainly to the beam damper 110 side which is the second branch optical path (99%) and partially (1%). Light leaks (reflects) to the movable mirror 191 side.

  The second polarizer 161, which is the second branching member, is located in the first branching optical path, and the laser beam 124 is incident thereon. Then, the laser beam is branched according to the polarization direction of the laser beam 124. In other words, the laser beam 125 transmitted through the second polarizer 161 and the laser beam 128 reflected by the second polarizer 161 are emitted.

  That is, as with the first polarizer 106, the second polarizer 161 cannot branch all the laser beams, and it is inevitable that a part of the laser beam leaks. In the present embodiment, when the polarization direction switched by the light modulation element 107 is an S wave, the laser light is branched (reflected) mainly to the workpiece side (99%), and a part (1%) of the light is It leaks (transmits) to the position sensor 181 side. On the other hand, when the polarization direction is P wave, the laser beam is branched (transmitted) mainly to the (99%) position sensor side, and a part (1%) of the light leaks (reflects) to the workpiece 111 side. .

  The fluorescent plate 171 is arranged upstream of the position sensor 181 with respect to the laser beam path. In addition, a filter 172 is disposed between the second polarizer 161 and the position sensor 181 downstream of the fluorescent plate 171 and transmits the fluorescent light emitted from the fluorescent plate 171 when it hits the laser beam, but blocks the laser light. Has been. In the present embodiment, the fluorescent plate 171 is disposed downstream of the second polarizer 161, and the filter 172 is disposed between the fluorescent plate 171 and the position sensor 181. The fluorescent plate 171 emits fluorescent light when the laser light 125 transmitted through the second polarizer 161 hits, and the fluorescent light transmitted through the filter 172 enters the position sensor 181.

  Here, the fluorescent plate 171 is used by selecting an appropriate excitation wavelength and emission wavelength from commercially available fluorescent glass and wavelength conversion materials. The filter 172 is a filter having a characteristic of transmitting the light having the wavelength of the fluorescence emitted from the fluorescent plate 171 but blocking the light having the wavelength of the laser beam 125.

  The position sensor 181 is a position sensor that detects the position of fluorescence emitted from the fluorescent plate 171 and passed through the filter 172, and is configured by an optical system such as a PSD, an ND filter, and a lens. Further, the optical system adjusts the incident light to an appropriate intensity, and at the same time, forms an image of the fluorescent light on the light detection element. As a result, a position variation or an angle variation of the laser beam 125 transmitted through the second polarizer 161 is detected. The position sensor 181 can detect, for example, an intensity range of ± 10% with respect to the set incident light intensity.

  The movable mirrors 191 and 192 are adjustment members that adjust the irradiation position of the laser beam on the workpiece 111 based on the detection result of the position sensor 181. Each of the movable mirrors 191 and 192 is, for example, a dielectric multilayer film mirror or a metal vapor deposition mirror, and changes the position and angle by a piezo element or a stepping motor to change the optical path of the reflected light. In the case of the present embodiment, the movable mirrors 191 and 192 are arranged so as to face each other, so that the irradiation position of the laser beam can be adjusted by changing the angle.

  When there is a part with different processing conditions in the workpiece 111, the laser beam intensity is changed using the function in the laser oscillator 104. In this case, since the paths are the same, the intensity of the laser light transmitted through the second polarizer 161 changes at a rate at which the intensity is changed. However, even if the intensity of the laser light incident on the fluorescent plate 171 is increased, the fluorescent light emitted from the fluorescent plate is saturated and high intensity fluorescent light is not emitted. Therefore, for example, even if the intensity of the laser light is increased ten times, the intensity of the fluorescent light remains at a certain value and does not exceed the input limit of the position sensor, so that the position can be detected.

  Note that the adjustment member that adjusts the irradiation position of the laser light may have a configuration in which one movable mirror is provided. In this case, not only the angle but also the position of the movable mirror can be changed. Further, the adjusting member may change the refractive index of light other than the movable mirror. That is, the optical path is changed by changing the refractive index, the irradiation position of the laser light is changed, and adjustment is performed. Such a refractive index can be changed by, for example, an electro-optic element (refractive index modulation) that is composed of an electrode and an electro-optic material (dielectric material), and changes the refractive index of light passing therethrough according to the strength of an applied electric field. Element) or the like. Alternatively, the lens may be moved. That is, the optical path can be changed by moving the lens and changing the position where the light is transmitted.

  The condensing lens 131 is an optical system that condenses laser light into a minute spot, or an optical system that is used together with the scanning mechanism 141, such as an fθ lens. The beam damper 110 absorbs one of the laser beams branched by the first polarizer 106. The stage 151 moves the workpiece 111 freely in the XYZ directions.

  The control device 108 controls the laser oscillator 104, the stage 151, the light modulation element 107, the position sensor 181, and the movable mirrors 191 and 192. The control device 108 also controls the scan mechanism 141.

  Next, the laser processing process of this embodiment is demonstrated, referring FIG. The laser oscillator 104 oscillates at a certain repetition frequency. Since the laser beam 121 is pulse-oscillated at a constant repetition frequency, there is no variation in excitation time, and the laser beam output stability is superior to the case where the repetition frequency is varied. The laser beam 121 is adjusted to a laser beam intensity suitable for the first processing by the power adjustment function in the laser oscillator 104 (laser beam intensity switching step, S101). Next, the direction of polarization of the laser light 121 can be changed by the light modulation element 107 in accordance with a control signal from the control device 108 for each pulse, and after passing through the light modulation element 107 of P-polarized light or S-polarized light. The laser beam 122 is selectively emitted (polarization direction switching step, S102).

  Here, when processing a portion of the workpiece 111 that is easy to process, a large intensity laser beam is applied to the workpiece 111 by irradiating the workpiece 111 with a low-intensity laser beam. The workpiece 111 is irradiated with intense laser light. The part that is easy to process is, for example, resin, and the part that is difficult to process is, for example, metal. In order to process these materials with a laser beam having an appropriate intensity, it is necessary to change the intensity by 10 times or more. When the processing of the workpiece 111 is stopped (not processed), the beam damper 110 is irradiated with a laser beam. For this reason, when processing the workpiece 111, the light modulation element 107 is controlled so that the workpiece 111 is irradiated with laser light. In the case of the present embodiment, if the light modulation element 107 is changed to the S wave (Y in S103), the laser beam is branched mainly to the movable mirror 191 side by the first polarizer 106 (first branching step, S104).

  In the case of the present embodiment, an energy loss of about 1% occurs when passing through the light modulation element 107, so the intensity of the laser beam 122 after passing through the light modulation element 107 is about 99% of the intensity of the laser beam 121. . Then, the laser beam 122 that has passed through the light modulation element 107 is then guided to the first polarizer 106.

  As described above, the first polarizer 106 reflects laser light with optical characteristics of P-polarized light transmittance of about 99%, reflectance of about 1%, S-polarized light transmittance of about 1%, and reflectance of about 99%. Make it transparent. Therefore, the workpiece 111 or the beam damper 110 is mainly irradiated with the laser beam after passing through the first polarizer 106 by the control of the polarization direction by the light modulation element 107 and the first polarizer 106. Or can be determined in units of one pulse.

  When processing the workpiece 111, the laser beam that passes through the light modulation element 107 is selected to be an S wave as described above. As a result, about 1% of the laser beam 122 is transmitted through the first polarizer 106 and irradiated to the beam damper 110. Further, about 99% of the laser beam 122 is reflected by the first polarizer 106, reflected by the movable mirrors 191 and 192, and guided to the second polarizer 161.

  As described above, the second polarizer 161 is the same as the first polarizer, and has a P-polarized light transmittance of about 99%, a reflectance of about 1%, an S-polarized light transmittance of about 1%, and a reflectance of about 99%. Laser light is reflected and transmitted with optical characteristics (second branching step, S105). At this time, since the laser beam guided to the second polarizer 161 is S-polarized light, the laser beam 125 transmitted through the second polarizer 161 is about 1% of the intensity of the laser beam 124 guided to the second polarizer 161. Thus, the laser beam 125 having this intensity enters the fluorescent plate 171.

  In other words, the intensity of the laser beam 125 is about 0.98% (= 99% × 99% × 1%) of the intensity of the laser beam 121. The fluorescent plate 171 emits fluorescent light 126 from where it hits the laser beam 125, and the fluorescent light 126 passes through the filter 172 and then enters the position sensor 181. At this time, when the laser beam 125 passes through the fluorescent plate 171, it becomes the fluorescent beam 127 blocked by the filter 172. The position sensor 181 appropriately adjusts the intensity of the fluorescent light 127 with an ND filter, a lens, and the like, and forms an image of a light emitting point on the fluorescent screen on the light detection element in the position sensor 181. As a result, the position sensor 181 to which the fluorescent light 127 is incident detects position variation and angle variation of the laser beam 125 (position detection step, S106).

  At this time, even if the laser beam 125 is pulsed light, the light emitted from the fluorescent plate is slowly extinguished, and the pulsed output of the position sensor 181 is flattened. Therefore, calculation such as integration for flattening the pulse signal performed in the control device 108 is not required, and the control becomes simpler.

  Then, the movable mirrors 191 and 192 are moved by the control device 108 so that the position of the fluorescent light 127 in the position sensor 181 becomes a predetermined position. That is, based on the detection result of the position sensor 181 in the position detection process, the irradiation position of the laser beam to the workpiece 111 is changed and adjusted (position change process, S107). Thereby, the position of the laser beam during processing can be automatically adjusted, and the irradiation position accuracy of the laser beam to the workpiece 111 is improved.

  On the other hand, the laser beam 128 reflected by the second polarizer 161 has an intensity of about 99% of the laser beam guided to the second polarizer 161. In other words, the intensity of the laser beam 128 reflected by the second polarizer 161 is approximately 97.03% (= 99% × 99% × 99%) of the intensity of the laser beam 121. The laser beam 128 reflected by the second polarizer 161 irradiates the workpiece 111 with the condensed light 129 that has passed through the scanning mechanism 141 and the condenser lens 131, and the workpiece 111 is processed (S108).

  Next, the output of the laser oscillator is changed to a laser intensity suitable for the second processing (laser light intensity switching step S101). At this time, the intensity of the second laser beam is about 10 times the intensity of the first laser beam. The subsequent steps S102 to S105 are the same as described above. Since the laser beam 125 leaking from the second polarizer 161 toward the position sensor 181 has ten times the first laser beam intensity, the intensity of the laser beam impinging on the fluorescent plate 171 is also ten times. However, the fluorescent light 127 adjusted by the fluorescent plate 171 and the filter 172 is within the allowable range of the position sensor 181, and no problem occurs in the position sensor 181 even if the laser light intensity becomes 10 times.

  Next, a description will be given of a case where the machining is stopped (non-machining) when the machining shape of the workpiece 111 becomes a desired shape or the workpiece 111 is moved to the next machining point. When the processing is stopped, the laser light transmitted through the light modulation element 107 is selected to be P-polarized light (N in S102 and S103).

  As a result, about 99% of the laser beam 122 is transmitted through the first polarizer 106 and irradiated to the beam damper 110 (first branching step, S109). Further, about 1% of the laser beam 122 is reflected by the first polarizer 106, reflected by the movable mirrors 191 and 192, and guided to the second polarizer 161.

  Since the laser beam guided to the second polarizer 161 is P-polarized light, the laser beam 125 transmitted through the second polarizer 161 has about 99% of the intensity of the laser beam guided to the second polarizer 161 to be the position sensor 181. Incident on the side (second branching step, S110). In other words, the intensity of the laser beam 125 transmitted through the second polarizer 161 is about 0.98% (= 99% × 1% × 99%) of the intensity of the laser beam 121.

  As described above, the phosphor plate 171 and the filter 172 are provided in front of the position sensor 181, and the change of the laser light intensity is relaxed and the pulsed light is flattened. Furthermore, the position is set in advance so that the position variation and the angle variation of the laser light of about 0.98% of the first intensity and the second intensity of the laser light 121 can be detected by an optical system such as an ND filter and a lens. . For this reason, the position sensor 181 detects the position variation and the angle variation of the laser beam 125 during the machining stop as well during the machining (position detection step, S111).

  Then, the movable mirrors 191 and 192 can be moved by the control device 108 so that the position of the laser beam 125 with respect to the position sensor 181 becomes a predetermined position (position changing step, S122). As a result, the irradiation position can be controlled with high accuracy even while the machining is stopped. Therefore, when switching from the machining stop to the machining, machining can be performed with high positional accuracy from the beginning.

  The laser beam 128 reflected by the second polarizer 161 has an intensity of about 1% of the laser beam guided to the second polarizer 161. In other words, using the laser beam 121 as a reference, the intensity of the laser beam 128 reflected by the second polarizer 161 is approximately 0.01% (= 99% × 1% × 1%) of the intensity of the laser beam 121. The laser beam 128 reflected by the second polarizer 161 is irradiated to the workpiece 111 through the condenser lens 131.

  Here, even if about 0.01% of the second intensity of the laser beam 121 is irradiated on the workpiece 111 by the oscillation condition of the laser oscillator 104 or the condenser lens 131, the processing threshold of the workpiece 111 is not exceeded. Conditions are set in advance. Thereby, even if the laser beam 128 reflected by the second polarizer is irradiated to the workpiece 111 via the condenser lens 131, the workpiece 111 is not processed (S113). The first and second processing, processing stop, and movement of the workpiece 111 by the stage 151 are performed until the desired processing is completed on the workpiece 111, and the processing ends.

  In the present embodiment, the laser beam branched by the first polarizer 106 and the second polarizer 161 hits the fluorescent plate, and the emitted light (fluorescent light) enters the position sensor 181 through a filter. Therefore, regardless of the intensity of the laser light applied to the workpiece 111, it can be within the intensity range determined by the position sensor 181. In the case of the present embodiment, the intensity of light entering the position sensor 181 falls within the input allowable range even when the workpiece 111 is processed with high laser light intensity or low laser light intensity. Even when the workpiece 111 is irradiated with a laser beam having a lower intensity when not being processed, the intensity of the laser beam incident on the position sensor 181 falls within the input allowable range of the position sensor. For this reason, the detection accuracy by the position sensor 181 can be maintained regardless of whether the first machining, the second machining, or the non-machining.

  Further, since the position sensor 181 detects the laser light after the first polarizer 106 and the second polarizer 161, the influence of air fluctuations and the like can be suppressed. That is, in the case of this embodiment, the position sensor 181 can be disposed at a position close to the workpiece 111, and the influence of air fluctuations can be minimized.

  In the case of the present embodiment, the laser light detected by the position sensor 181 can be within the intensity range determined by the position sensor 181 between when the processing with different laser light intensities is performed alternately and when not processing. The detection by the position sensor 181 can be performed at a position close to the workpiece 111. As a result, the laser beam irradiation position can be adjusted more accurately.

  The positions of the movable mirrors 191 and 192 can be arranged at other positions as long as they are upstream of the position sensor 181 and the fluorescent plate with respect to the laser beam path. Further, the polarization extinction ratio characteristics of the first polarizer 106 and the second polarizer 161 may not be the same. However, in this case, the combination is such that the laser light incident on the position sensor 181 falls within the allowable range of the position sensor 181 during processing and during non-processing. Further, the relationship between the P wave and the S wave may be reversed.

  Examples of the substrate manufactured by the laser processing apparatus and the laser processing method described in the above embodiments include an inkjet head substrate, another semiconductor material substrate, a glass substrate, and a circuit substrate. Further, the processing is not limited to drilling such as a leading hole, and processing such as groove shape, cutting, reforming, and joining can also be performed. The specific application destination is not limited to the lead hole processing of the ink jet head, but includes, for example, drilling of a circuit board, scribing of a solar cell substrate, trimming of a resistance element, sealing welding of a battery case, and the like.

<Example>
Next, as an example, a substrate manufacturing method for manufacturing a substrate using the laser processing apparatus and the laser processing method described in each embodiment will be described. In this embodiment, the substrate to be manufactured is an inkjet head substrate. FIG. 7 is a cross-sectional view of the head portion of the ink jet printer.

  In FIG. 7, 40 is a semiconductor substrate (inkjet head substrate), and 41 is a vertical groove serving as an ink path. Further, 42 is a heater, 43 is a liquid chamber, 44 is an orifice plate, 45 is an ejection hole, 46 is an ink tank, 47 is indicated by a broken line 47 is an ink path, and 48 is a minute ink droplet. A heater 42 for discharging ink, a liquid chamber 43, and an orifice plate 44 are formed on the lower surface of the semiconductor substrate 40 in which the groove 41 is formed. An ink tank 46 for storing ink is attached to the upper surface of the semiconductor substrate 40. The ink reaches the heater 42 from the ink tank 46 through the groove 41 and the liquid chamber 43. Bubbles formed by instantaneous heating / cooling of the heater 42 push up the ink, and are ejected as minute ink droplets 48 from the ejection holes 45 formed in the orifice plate 44.

  In this embodiment, the groove 41 serving as a path for supplying ink to the ejection holes 45 that eject the ink droplets 48 is formed by laser processing as described in the above embodiments. That is, the semiconductor substrate before forming the groove 41 as a workpiece is placed on the stage, and the laser processing as described above is performed. Although it may be used as it is after laser processing, the final groove shape may be formed by anisotropic etching in an alkaline etching solution for about 15 minutes, for example.

  When the groove 41 is formed by anisotropic etching, the leading hole is formed by laser processing. The leading hole is for allowing an etchant to enter during anisotropic etching in a post-process of laser processing, shortening the anisotropic etching time, and reducing the width of the ink supply port.

  In addition, the substrate of the inkjet head is manufactured by processing a crystal surface (100) silicon material (workpiece), for example. A mechanism for discharging ink, an etching process after laser processing, and the like are formed on the workpiece, such as a heater, electric wiring, an etching stop layer having etching resistance, and an etching protective film. Moreover, the thickness of a to-be-processed object is about 725 micrometers, for example.

  Such a workpiece is irradiated with laser light until the shape of the above-described desired leading hole is obtained. The lead hole has a diameter of 5 to 100 μm in order to allow an etchant to enter during anisotropic etching in a later step, shorten the time of anisotropic etching, and further reduce the width of the ink supply port. Is preferred. The depth is preferably 600 to 710 μm when a workpiece having a thickness of 725 μm is used.

  DESCRIPTION OF SYMBOLS 11,111 ... Workpiece, 12 ... Another workpiece, 4,104 ... Laser oscillator, 6,106 ... 1st polarizer (1st branch member), 61,161 ... 2nd polarizer (second branch member), 62 ... 3rd polarizer (second branch member), 7, 107 ... Light modulation element (polarization direction switching member), 8, 108 ... Control device, 81,181 ... Position sensor, 82 ... Another position sensor, 9 ... Mirror, 91, 92,191,192 ... Movable mirror (adjustment member) ... Beam damper, 20 ... Mirror, 171 ... Fluorescent screen, 172 ... Filter

Claims (8)

A laser oscillator;
A position sensor for detecting the position of the laser beam irradiated by the laser oscillator;
Based on the detection result of the position sensor, a position changing member that changes the irradiation position of the laser beam on the workpiece;
A polarization direction switching member that switches the polarization direction of the laser light emitted by the laser oscillator between a first polarization direction and a second polarization direction;
With respect to the path of the laser light, a first branching member that is arranged between the polarization direction switching member and the position sensor, and each branches the laser light according to the polarization direction switched by the polarization direction switching member, and Two branch members,
The first branch member is configured such that the laser beam is mainly in the first branch optical path when the polarization direction switched by the polarization direction switching member is the first polarization direction, and the polarization direction is the second polarization direction. In the case of the polarization direction, the light is mainly branched to the second branch optical path and a part is branched to the first branch optical path.
The second branch member is located in the first branch optical path, and the laser beam is mainly on the workpiece side when the polarization direction is the first polarization direction, and partly on the position sensor side. In addition, when the polarization direction is the second polarization direction, it mainly branches to the position sensor side, respectively.
The laser processing apparatus characterized by the above-mentioned. The first branch member and the second branch member have the same polarization extinction ratio characteristic that is a ratio of mainly splitting the incident laser light according to the polarization direction.
The laser processing apparatus according to claim 1, wherein: A fluorescent plate disposed upstream of the position sensor with respect to a laser beam path;
A filter that is disposed downstream of the fluorescent plate and between the second branch member and the position sensor and transmits the fluorescent light emitted by the fluorescent plate when it hits the laser light, but blocks the laser light; Have
The laser processing apparatus according to claim 1 or 2, wherein A polarization direction switching step of switching the polarization direction of the laser light irradiated by the laser oscillator between the first polarization direction and the second polarization direction;
A position detecting step of detecting the position of the laser beam irradiated by the laser oscillator by a position sensor;
Based on the detection result by the position sensor in the position detection step, a position change step for changing the irradiation position of the laser beam to the workpiece,
Before the position detection step, and having a first branching step and a second branching step for branching the laser beam according to the polarization direction switched by the polarization direction switching step,
In the first branching step, when the polarization direction switched in the polarization direction switching step is the first polarization direction, the laser beam is mainly in the first branch optical path, and the polarization direction is in the second branching direction. In the case of the polarization direction, the light is mainly branched to the second branch optical path and a part is branched to the first branch optical path.
In the second branching step, the laser beam branched into the first branching optical path is mainly on the workpiece side when the polarization direction is the first polarization direction, and partly on the position sensor side. In addition, when the polarization direction is the second polarization direction, it mainly branches to the position sensor side, respectively.
The laser processing method characterized by the above-mentioned. The position sensor detects the position of the laser light by making the fluorescent light emitted from the fluorescent screen incident upon the laser light hitting it,
The laser processing method according to claim 4. A substrate manufacturing method for processing a workpiece to manufacture a substrate,
A laser processing step of performing laser processing on the workpiece;
The laser processing step includes
A polarization direction switching step of switching the polarization direction of the laser light irradiated by the laser oscillator between the first polarization direction and the second polarization direction;
A position detecting step of detecting the position of the laser beam irradiated by the laser oscillator by a position sensor;
Based on the detection result by the position sensor in the position detection step, a position change step for changing the irradiation position of the laser beam to the workpiece,
Before the position detection step, and having a first branching step and a second branching step for branching the laser beam according to the polarization direction switched by the polarization direction switching step,
In the first branching step, when the polarization direction switched in the polarization direction switching step is the first polarization direction, the laser beam is mainly in the first branch optical path, and the polarization direction is in the second branching direction. In the case of the polarization direction, the light is mainly branched to the second branch optical path and a part is branched to the first branch optical path.
In the second branching step, the laser beam branched into the first branching optical path is mainly on the workpiece side when the polarization direction is the first polarization direction, and partly on the position sensor side. In addition, when the polarization direction is the second polarization direction, it mainly branches to the position sensor side, respectively.
A method for manufacturing a substrate, comprising: The substrate is a substrate of an inkjet head having a groove serving as a path for supplying ink to an ejection hole for ejecting ink droplets;
The laser processing step is a step of performing laser processing on a workpiece to form the groove.
The method of manufacturing a substrate according to claim 6. The position sensor detects the position of the laser light by making the fluorescent light emitted from the fluorescent screen incident upon the laser light hitting it,
The method for manufacturing a substrate according to claim 6 or 7, wherein:

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