JP5036144B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus. For example, the present invention relates to a laser processing apparatus that performs removal, cutting, and the like of a specified region of a workpiece by irradiating laser light.

2. Description of the Related Art Conventionally, a laser processing apparatus that performs processing by irradiating a desired region of a workpiece with laser light is known. For example, in the manufacture of a liquid crystal display or the like, a laser repair apparatus is known as means for correcting a defective portion such as an unnecessary residue existing in a wiring pattern on a glass substrate or a photomask used for exposure.
In this laser processing apparatus, the size of the laser light irradiation area is defined by a variable rectangular opening or the like, but recently, an apparatus using a spatial modulation element such as a micromirror array is also known.
For example, Patent Document 1 includes a laser source, a processing table on which a workpiece is placed, and a micromirror array (micromirror array). The angles of a plurality of mirror pieces of the micromirror array are turned ON / OFF. A laser processing apparatus is described in which an arbitrary pattern shape is formed on a workpiece by switching by control.
As the wavelength of the laser used in the laser processing apparatus, an appropriate wavelength is selected depending on the processing target. For example, in a laser repair apparatus, a wavelength that is easily absorbed by a workpiece is used, such as a visible to infrared band for correcting a metal film and an ultraviolet band for a transparent film. In order to switch the wavelength, there are devices equipped with a plurality of lasers, devices capable of switching a plurality of harmonics of one fundamental wavelength laser, and the like.
JP-A-8-174242 (page 3-4, FIG. 1-2)

However, when laser processing using laser light is performed by a laser processing apparatus using an active optical element in which a plurality of active optical elements are regularly arranged, such as a micromirror array, as in Patent Document 1, a micro-array is simply used. There is a problem that a phenomenon of reducing the use efficiency of laser light occurs only by setting the optical axis of a microscope that irradiates laser light in the regular reflection direction by the mirror.
In a laser processing apparatus using a micromirror array, an image of the micromirror array is reduced and projected onto a workpiece with a microscope. Since the micromirror array has a structure in which small mirrors are arranged at equal intervals, the laser light reflected from the micromirror array is divided into a plurality of diffracted lights. However, since the rear numerical aperture of the microscope is generally small, it is not possible to enter all of the divided diffracted lights.

As a result, inconvenience may be described with reference to FIG.
FIG. 7 shows an example of the angular distribution of diffracted light in a laser processing apparatus capable of switching the second harmonic (wavelength λ ₂ = 532 nm) and the third harmonic (wavelength λ ₃ = 354.7 nm) of the YAG laser. That is, the angle distribution (α, β) of the diffracted light reflected from the micromirror array is plotted on an angle plane 501 with the optical axis 502 of the microscope as the center.

At the wavelength λ ₃ , there is one diffraction order 504 in the vicinity of the optical axis 502, as indicated by a cross in the figure. Since the small mirror corresponding to the irradiation region of the laser beam is inclined so as to reflect the laser beam in the direction of the optical axis 502, the diffraction order 504 close to the optical axis 502 is the only diffracted light having a large intensity. Since this diffraction order 504 is within the range of the rear-side angular opening 503 of the microscope, the work piece can be efficiently irradiated with the intensity of the laser beam.
On the other hand, when switching the wavelength lambda _2, as shown in the illustrated circle, diffraction orders near the optical axis 502 is no, the similar angle position spaced four diffraction orders 505 are present. Therefore, the intensity of the laser is dispersed in the plurality of diffraction orders 505 and does not enter the rear angle opening 503 of the microscope. That is, when the wavelength λ ₂ is used, one diffraction order can be made incident by changing the incident angle with respect to the microscope, but the utilization efficiency of the laser beam is still not improved.

  Therefore, the present invention solves such a problem, and can improve the utilization efficiency of laser light when performing laser processing, and thereby a laser processing method capable of processing a workpiece efficiently, and An object is to provide an apparatus.

In order to solve the above problems, a laser processing apparatus of the present invention includes a laser light source for generating a laser beam, for spatially modulating the laser beam, a plurality of deflection elements which can be deflected in at least two directions regularly An array of spatial modulation elements , a modulated light irradiation optical system that irradiates a workpiece with modulated light formed by reflecting the laser light by the spatial modulation element , and an optical axis of the modulated light irradiation optical system A rotation mechanism that varies an inclination of an incident optical axis of the laser light incident on the spatial modulation element and an inclination of the spatial modulation element, and is incident on the modulated light irradiation optical system by the rotation mechanism. The modulated light is configured to have a variable exit angle with respect to the spatial modulation element.
According to this invention, the tilt of the incident optical axis of the laser light and the tilt of the spatial modulation element can be varied with respect to the optical axis of the modulated light irradiation optical system by the rotation mechanism, and thereby the modulated light irradiation optical system The emission angle of the modulated light incident on the optical axis of the spatial light modulation element can be varied. Therefore, even if the modulated light is diffracted by the spatial modulation element, the modulated light incident on the modulated light irradiation optical system can be matched with an appropriate diffraction direction. Therefore, light having high diffraction efficiency can be made incident on the modulated light irradiation optical system as the modulated light.
In addition, since the emission angle of the modulated light incident on the modulated light irradiation optical system with respect to the spatial modulation element can be changed, the diffracted light of the order is appropriately adjusted according to the wavelength of the laser light and the incident angle to the spatial modulation element. be able to. Therefore, modulated light with high diffraction efficiency can be incident on the modulated light irradiation optical system.
Further, by combining the rotation of the rotation mechanism, it is possible to optimize the diffraction conditions of the modulated light incident on the modulated light irradiation optical system.
In addition, if the laser light source can be rotated in accordance with the rotation of the spatial modulation element, the emission angle of the modulated light can be varied under the condition that the incident angle of the laser beam is constant, so that the rotation control is easy. Thus, the diffraction order of the modulated light can be changed efficiently.

Moreover, in the laser processing apparatus of this invention, it is preferable that the said rotation mechanism is a structure provided with the mechanism rotated so that the inclination of the said laser light source with respect to the said spatial modulation element may be changed.
In this case, since the tilt of the laser light source can be changed with respect to the spatial modulation element by the rotation mechanism, the incident angle of the laser beam with respect to the spatial modulation element can be changed when the spatial modulation element is fixed. it can. Therefore, the modulated light traveling along the optical axis of the modulated light irradiation optical system can be appropriately matched to the diffracted light of the order according to the wavelength of the laser light and the incident angle to the spatial modulation element. Therefore, modulated light with high diffraction efficiency can be incident on the modulated light irradiation optical system.

In the laser processing apparatus of the present invention, the diffraction direction of the modulated light is calculated from the rotation position of the rotation mechanism and the wavelength of the laser light, and the diffraction direction is the optical axis of the modulated light irradiation optical system. It is preferable to provide a rotation mechanism control unit that drives the rotation mechanism so as to substantially match.
In this case, since the diffraction direction of the modulated light can be calculated by the rotation mechanism control unit and the optical axis of the modulated light irradiation optical system can be made to substantially coincide with the diffraction direction, the diffraction efficiency can be automatically optimized.

Moreover, in the laser processing apparatus provided with the rotation mechanism control unit of the present invention, the laser light source generates two or more different wavelengths of laser light in a switchable manner, and the rotation mechanism control unit includes the respective lasers. It is preferable to make the optical axis of the modulated light irradiation optical system substantially coincide with the diffraction direction common to the wavelength of light.
In this case, when performing laser processing using laser light of a plurality of wavelengths, the diffraction efficiency of the modulated light can be brought into an optimal state without readjusting the rotation mechanism even if the wavelength is switched. Laser processing with switched wavelengths can be performed quickly, and processing efficiency can be improved.

In the laser processing apparatus of the present invention, the spatial modulation element is a micromirror array including a plurality of micromirrors that switch the tilt angle and deflect the laser light in at least two directions as the plurality of deflection elements. It is preferable that
In this case, in order to improve the diffraction efficiency of the modulated light, the rotating mechanism makes the diffraction direction of the modulated light coincide with the optical axis of the modulated light irradiation optical system. The diffraction efficiency of modulated light can be easily optimized, and high-speed and highly efficient laser processing can be performed.

  According to the laser processing apparatus of the present invention, even if the laser light is diffracted by the spatial modulation element, the diffraction direction of the modulated light can be substantially matched with the modulated light irradiation optical system by the rotation mechanism. The efficiency can be improved, thereby producing an effect that the workpiece can be processed efficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

A laser processing apparatus according to an embodiment of the present invention will be described.
FIG. 1 is a schematic explanatory diagram for explaining a schematic configuration of a laser processing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic optical path explanatory diagram for explaining an optical path in the vicinity of the spatial modulation element used in the laser processing apparatus according to the embodiment of the present invention.

As shown in FIG. 1, the laser processing apparatus 100 according to the present embodiment processes laser beams L ₂ and L ₃ having wavelengths of λ ₂ and λ ₃ as modulated light L _M according to a processing pattern. It is an apparatus that performs laser processing by irradiating an object 15.
Examples of the workpiece 15 include a glass substrate used for a liquid crystal display and a semiconductor substrate. In these cases, examples of the processing target include a wiring pattern on the substrate and a defective portion such as an unnecessary residue existing in a photomask used for exposure. Moreover, when using for a microdissection apparatus, biological samples, such as a cell, etc. can be mentioned.
Although not particularly illustrated, the workpiece 15 is held on a mounting table provided with a holding mechanism, a suction mechanism, and a moving mechanism for moving the processing position, for example, as necessary, for example, to fix the position during processing. .
The laser beams L ₂ and L ₃ are switched and used in accordance with the wavelength absorption characteristics of the processing target.

  The schematic configuration of the laser processing apparatus 100 includes a laser oscillator 1 (laser light source), an inclination stage 4 (rotation mechanism), a micromirror array 7 (spatial modulation element), an inclination stage 5 (rotation mechanism), and an irradiation optical system 20 ( A modulation light irradiation optical system) and a control unit 16.

The laser oscillator 1 is a laser light source that pulsates laser light having a plurality of wavelengths and emits it as a substantially parallel light beam. In the present embodiment, a YAG laser having a fundamental wavelength λ ₁ = 1.064 μm is used, and the second and third harmonics (wavelength λ ₂ = 532 nm and λ ₃ = 354.7 nm, respectively) are switched, and the laser light L _{2 is} respectively switched. , L ₃ can be emitted on the same optical path.
The beam diameters of the laser beams L ₂ and L ₃ are set to a size that can sufficiently cover a reference reflection surface 7a of a micromirror array 7 to be described later. Therefore, although not particularly illustrated, the laser oscillator 1 is appropriately provided with an optical system such as a beam expander or a diaphragm for regulating the beam diameter as necessary.

The tilt stage 4 is a rotation mechanism that supports the laser oscillator 1 so as to be rotatable about a rotation center 4C provided on the optical axis of the laser beam L ₂ (L ₃ ). For example, a gonio stage can be employed. The rotation direction may be about one axis or two axes as necessary. For example, a stage drive unit 4a including a feed screw mechanism driven by a stepping motor is provided, and a rotation operation is controlled by a control unit 16 described later in accordance with a control signal.

The optical path of the laser beam _L 2 emitted from the laser oscillator 1 _{(L 3)} includes an optical attenuator 3 for adjusting the amount of the laser beam _L 2 _{(L 3),} the cross section of the laser beam _L 2 _{(L 3)} A homogenizer 2 is provided as a homogenizing optical system for homogenizing the intensity distribution.
Since the homogenizer 2 is known to have various configurations such as a fly-eye lens, a diffraction element, an aspheric lens, and a kaleido rod, any configuration may be adopted as necessary.

As shown in FIG. 2, when the tilt angle is 0 °, the micromirror array 7 is aligned on the reference reflecting surface 7a and can tilt in a predetermined direction according to a control signal. A large number of deflection elements) are regularly arranged in a grid pattern in the vertical and horizontal directions. For example, an element such as DMD (Digital Micro mirror Device) in which 800 × 600 16 μm square micro mirrors 7b are arranged in a rectangular region can be employed.
Each micromirror 7b is inclined at two inclination angles, for example ± 12 °, between an on state and an off state by a drive unit (not shown) that generates an electrostatic electric field in accordance with a control signal. Yes.
Therefore, the micromirror array 7 forms a modulated light L _M of the cross-sectional shape corresponding to the control signal is reflected by the micro mirror 7b of the incident laser beam L _{2 (L 3)} in the ON state at a certain angle of incidence , by reflecting the light reflected by the micromirror 7b in the oFF state in the optical path different from an optical path of the modulated light L _M (see a broken line arrow in FIG. 5), carrying out the spatial modulation of the laser beam L _{2 (L 3)} It is something that can be done.

For example, FIG. 2 shows an on-state micromirror 7b in which the micromirror 7b is tilted from the reference reflecting surface 7a counterclockwise by an inclination angle φ _ON = 12 °. A symbol N indicates a normal line of the reference reflecting surface 7a. The laser beam L ₂ (L ₃ ) incident on the reference reflecting surface 7a at an angle θ _i is reflected by the small mirror 7b and reflected in the regular reflection direction R. However, in FIG. 2, even if the angle is the same, the angle is shifted for ease of viewing.
On the other hand, the plurality of micromirrors 7b arranged at an equal pitch and inclined in the same direction act as a diffraction grating for the laser light L ₂ (L ₃ ). Therefore, the laser beam L ₂ (L ₃ ) is diffracted according to the wavelength and the arrangement pitch of the micromirrors 7b.
Therefore, the light intensity in each diffraction direction corresponding to the diffraction order is increased, and in the direction between them, the diffraction efficiency decreases and the light intensity decreases. 2, the diffraction direction D which is inclined by an angle theta _D from the normal N, illustrates the diffraction direction common to the laser light L _2, L ₃ of these diffraction direction.

The tilt stage 5 is a rotation mechanism that supports the micromirror array 7 so as to be rotatable about a rotation center 5C located substantially at the center of the reference reflecting surface 7a. For example, a gonio stage can be employed. The rotation direction may be about one axis or two axes as necessary. For example, a stage drive unit 5a including a feed screw mechanism driven by a stepping motor is provided, and a rotation operation is controlled by a control unit 16 described later in accordance with a control signal.
The rotation center 5C and the rotation center 4C of the tilt stage 4 are substantially coincident.

As shown in FIG. 1, the irradiation optical system 20 includes an imaging lens 11 and an objective lens 14 that are arranged so that an optical axis 202 passes through rotation centers 4C and 5C, a reference reflecting surface 7a, a workpiece 15, and the like. Is an imaging optical system provided so as to be substantially conjugate. For example, an optical system such as a microscope can be employed.
The objective lens 14 is designed at infinity on the image side, and the laser light L ₂ (L ₃ ) is substantially parallel light between the imaging lens 11 and the objective lens 14.
This on the optical path of the substantially parallel light, semi-transparent mirror 12 that transmits the modulated light L _M is transmitted through partially reflects part of the emitted illumination light L _ob from the light source 13 is provided. Therefore, the illumination light L _ob is guided on the same optical path as that of the modulated light L _M so that the workpiece 15 can be illuminated.
The wavelength of the illumination light L _ob may be any wavelength as long as it can be imaged by the CCD 10 to be described later, and can be set, for example, in the wavelength region of visible light.
The semi-transparent mirror 12 may employ, for example, a light splitting element such as a half mirror, a reflecting plate with a coating having such wavelength characteristics, or a prism.

Further, in the optical path between the imaging lens 11 and the micro mirror array 7, and transmits the modulated light L _M, semi-transparent mirror 8 for reflecting the illumination light L _ob reflected by the workpiece 15 is provided . Therefore, when the illumination light L _ob is reflected by the workpiece 15 and returns to the semi-transparent mirror 8, the optical path is branched. The semi-transparent mirror 8 can adopt the same configuration as the semi-transparent mirror 12.
On the optical path branched by the semi-transparent mirror 8, a CCD 10 for capturing an image on the workpiece 15 is disposed at a position substantially conjugate with the surface of the workpiece 15.

The control unit 16 performs overall control of the laser processing apparatus 100, and includes an operation unit 17 for performing operation input, a CCD 10, a monitor for displaying operation inputs from the operation unit 17 and image signals sent from the CCD 10. 9 is connected.
In addition, it is electrically connected to at least the laser oscillator 1, the micromirror array 7, and the stage drive units 4a and 5a that are to be controlled, and control signals for controlling their operations can be sent to each of them. .
To the laser oscillator 1, based on an operation input from the operation unit 17, one of the laser beams L ₂ and L ₃ is selected and a control signal for turning on or off is transmitted.
Further, with respect to the micro mirror array 7, by detecting the image processing area to be edited with the image of the workpiece 15 captured by CCD 10, in a region to be processed an irradiation area of the modulated light L _M A control signal for controlling the on state and the off state of each micromirror 7b is sent out so as to match.

  For the stage drive units 4a and 5a, the diffraction direction D (see FIG. 2) is calculated according to the wavelength of the laser beam set by the operation unit 17, and the diffraction direction D coincides with the optical axis 202. In this way, a control signal for rotating at least one of the tilt stages 4 and 5 is sent. That is, the control unit 16 constitutes a rotation mechanism control unit that drives the rotation mechanism.

Here, a method for setting the diffraction direction D will be described.
FIG. 3 is an angle distribution diagram for explaining the diffraction direction after rotation control of the diffracted light emitted from the spatial modulation element of the laser processing apparatus according to the embodiment of the present invention. FIG. 4 is a schematic optical path explanatory diagram for explaining an example of optical axis setting of the laser processing method according to the embodiment of the present invention.

In the micromirror array 7, since the micromirrors 7b having a square reflecting surface are arranged in a vertical and horizontal grid pattern, the diffracted light is distributed two-dimensionally. Depending on the arrangement relationship of the laser oscillator 1, the micromirror array 7, and the irradiation optical system 20, each diffraction is performed with respect to the optical axis 202 of the irradiation optical system 20 located at (α ₀ , β ₀ ) as shown in FIG. The direction is distributed independently. Here, the circle indicates the diffraction direction of the laser light L _{2 having} the wavelength λ _{2, and} the cross indicates the diffraction direction of the laser light L _{3 having} the wavelength λ ₃ . Reference numeral 203 denotes a rear corner opening of the irradiation optical system 20.
Further, since the laser beams L ₂ and L ₃ are harmonics of the fundamental wavelength λ ₁ , the ratio of the wavelengths λ ₂ and λ ₃ is an accurate integer ratio 3: 2. _Therefore, m x, when the _{m y} an integer, the diffraction order of the laser beam _{L 2 (2 · m x,} 2 · m y) Next, the diffraction order of the laser beam _{L 3 (3 · m x,} 3 · m y) The following diffraction directions coincide with each other.

In this case, for example, at the wavelength λ ₃ , diffracted light in the diffraction direction 206 in the vicinity of the optical axis 202 is substantially incident, so light having high diffraction efficiency is incident. On the other hand, when switching to the wavelength λ ₂ , the light incident on the irradiation optical system 20 is dispersed in the three types of diffraction directions 207 and becomes light with low diffraction efficiency, and the amount of incident light decreases.
Therefore, in the present embodiment, at least one of the tilt stages 4 and 5 is driven to rotate the diffraction direction so that the state shown in FIG. 3 is obtained. That is, the diffraction directions 204 and 205 corresponding to the diffraction orders having the same diffraction direction are moved to the position (α ₀ , β ₀ ).

Hereinafter, the positional relationship in the diffraction direction will be described using a cross section including the optical path. However, for simplicity, description will be made using a one-dimensional diffraction model shown in FIG.
When the fundamental wave, the second harmonic wave, and the third harmonic wave of the YAG laser are incident on the micromirror array 601 as the incident light 602 at the incident angle θ _i , the diffraction angle θ _d of each diffracted light is given by Expressed by diffraction conditions.
sin θ _d −sin θ _i = p · λ _i / T (2)
Here, p is the diffraction order, λ _i is the wavelength of the incident light 602, and T is the arrangement pitch of the micromirror array 601.
The 0th-order diffracted lights 610, 620, and 630 of the fundamental wave, the second harmonic wave, and the third harmonic wave are obtained when p = 0 in the equation (2), and the micromirror of the micromirror array 601 is the reference reflecting surface. It is the specularly reflected light when they are aligned.
When p is not 0, the condition that the diffraction angles θ _d are equal is that p · λ _i is constant from equation (2).
λ ₂ = λ _1/2, since it is λ ₃ = λ _1/3, as shown in FIG. 4, the diffraction direction is equal to the wavelength lambda ₁ of the first-order diffracted light 611 (p = 1), the wavelength lambda the second harmonic of _2, a second-order diffracted light 622 (p = 2), the third harmonic of the wavelength lambda _3, is a 3-order diffracted light 633 (p = 3). In general, the diffraction direction of the u-th harmonic (u · m) -order diffracted light coincides with the diffraction direction of the fundamental-order m-th order diffracted light.
The second harmonic first-order diffracted light 621 and the third harmonic first-order diffracted light 631, second-order diffracted light 632 are diffracted in different diffraction directions.

For example, when the arrangement pitch of the micromirrors of the micromirror array 601 is T = 16 μm, when a second harmonic wave having a wavelength of 532 nm is incident at an incident angle θ _i = 23.8 °, the 12th (= 2 × 6) order diffracted light The diffraction angle is θ _d = 0.2 °. When a third harmonic wave having a wavelength of 354.7 nm is incident at the same incident angle θ _i , the diffraction angle of the 18 (= 3 × 6) order diffracted light becomes θ _d = 0.2 °, and both coincide with each other. To do.
Therefore, the tilt stage 5 is rotated so that the diffraction direction D coincides with the optical axis 202, and the incident angles of the laser beams L ₂ and L ₃ with respect to the reference reflection surface 7a at that time are the above θ _i and The tilt stage 4 is rotated so that In this way, even if the wavelength of the YAG laser is switched, the incident condition to the optical system after the micromirror array 601 does not change, and the utilization efficiency of the laser light quantity can be maximized.
Even when the micromirror array 7 having a different tilt angle φ _ON of the small mirror 7b is used, the incident angle θ _i that maximizes the light utilization efficiency is calculated in the same manner. It can be rotated. Therefore, the inclination angle phi _ON is not limited to the 12 °.

The above has been described with an example in which the diffraction order is one-dimensional, but the same applies to a general case where the diffraction order is two-dimensional. That is, the u harmonic, m _x, a m _y is an _{integer, (u · m x, u} · m y) since the diffraction direction of the diffracted light are all exactly match, fit the incident angle and the diffracted direction By rotating the tilt stages 4 and 5, the diffraction efficiency can be maximized.
FIG. 1 illustrates such a state. The diffracted light 121 corresponds to the diffraction direction 204 (205) in FIG. 3, and the diffracted lights 120 and 122 correspond to other diffraction directions.

Note that since the diffraction direction D is a function of the two-dimensional incident angle θ _i , the degree of freedom for angle adjustment is only two degrees. Therefore, when the tilt stages 4 and 5 are each rotated about two axes, the adjustment can be performed by rotating only one of them. Further, the tilt stages 4 and 5 may be rotated around one axis in an independent direction.

Next, the operation of the laser processing apparatus 100 according to this embodiment will be described.
FIG. 5 is a schematic explanatory diagram for explaining an initial state of the laser processing apparatus according to the embodiment of the present invention.
In the initial state of the laser processing apparatus 100, as shown in FIG. 5, the tilt stages 4 and 5 are set to the reference position for rotation, and the positional relationship between the laser oscillator 1 and the micromirror array 7 is not optimized. Therefore, in general, when the laser beam L ₂ (L ₃ ) is irradiated in this state, all of the diffracted beams 120, 121, 122, etc. are displaced from the optical axis 202, and the irradiation optical system 20 as shown in FIG. As a result of the light incident on the light being dispersed into the plurality of diffracted lights, the light intensity irradiated on the workpiece 15 is reduced.

Therefore, an initial setting operation for optimizing the rotation positions of the tilt stages 4 and 5 is performed before the laser beam is irradiated.
That is, the positional relationship between the laser oscillator 1 and the micromirror array 7 that matches the common diffraction direction D and the optical axis 202 with respect to the wavelengths λ ₂ and λ ₃ of the laser light that can be emitted is set as the diffraction direction setting method described above. And a control signal corresponding to the rotation position of the tilt stages 4 and 5 is sent to the tilt stages 4 and 5.

Next, using the laser processing apparatus 100, processing pattern data for performing laser processing is created. For this purpose, the illumination light L _Ob is emitted from the light source 13, reflected by the semi-transparent mirror 12, and illuminated on the workpiece 15 through the objective lens 14.
The reflected light of the illumination light _{L ob} the objective lens 14, half mirror 12, it reflected the imaging lens 11 in the half mirror 8 passes through each of which is imaged by the CCD 10. Then, the image of the surface of the workpiece 15 by the illumination light L _ob is sent to the control unit 16 as an image signal 150A.
The control unit 16 converts the image signal 150A into image data and displays it on the monitor 9. Then, the operator observes the image on the monitor 9 and designates a defective part or a cut part to be processed through the operation part 17, or the control part 16 performs image processing on the image data to automatically extract the defective part or the cut part. Then, processing pattern data 151 corresponding to the image data of the defective portion and the cut portion is created.
The processing pattern data 151 is control data that associates the irradiation region of the laser light with the on state of each micromirror 7 b of the micromirror array 7.

Next, the operator selects a wavelength to be used for laser processing, for example, λ ₂ from the operation unit 17, performs an operation input for instructing the start of processing, and starts a laser processing step.
In the laser processing step, the control unit 16 transmits a control signal for oscillating the laser light L ₂ to the laser oscillator 1 and transmits processing pattern data 151 to the micromirror array 7.
The light intensity of the laser light L ₂ is adjusted by the light attenuator 3, the light intensity distribution in the cross-sectional direction is made uniform by the homogenizer 2, and the laser light L ₂ is incident at a constant incident angle θ _i with respect to the reference reflecting surface 7 a of the micromirror array 7. Incident.

In the micro mirror array 7, for each of the micromirrors 7b are inclined angle is controlled to and the OFF state ON state processing pattern data 151 corresponding to, among the laser beam L _2, is incident on the micromirror 7b of on-state portion Only the regular reflection direction R (see FIG. 2) is reflected.
At this time, diffraction occurs in the region where the on-state micromirrors 7b gather, and the diffraction is performed in a direction corresponding to the diffraction order. In the present embodiment, since the diffraction direction D and the regular reflection direction R coincide with each other, the light is not reflected in the state where the diffraction efficiency is maximized, and is reflected in the direction of the emission angle θ _o (see FIG. 2). Then, it passes through the semi-transparent mirror 8.
Then, the light enters the imaging lens 11 in which the optical axis 202 is arranged so as to coincide with the diffraction direction D, and is imaged on the workpiece 15 by the objective lens 14. Thus, the modulated light L _M is irradiated in a region corresponding to the machining pattern data 151 on the workpiece 15. for that reason. Regions corresponding to the processing pattern data 151 is laser machined by the modulated light L _M.
On the other hand, the light reflected by the micro mirror 7b in the off state is reflected in a direction not incident on the imaging lens 11, and thus does not reach the workpiece 15.

Thus, in the laser processing apparatus 100, a processing pattern of a region to be laser processed is created from the image of the workpiece 15, and the region corresponding to the processing pattern can be processed by irradiating one shot of laser light. It is.
Then, an operation input for switching the wavelength of the laser beam used for processing is performed from the operation unit 17, and a control signal for switching the wavelength of the laser beam is transmitted to the laser oscillator 1 by the control unit 16, thereby switching the wavelength and performing laser processing. It can be carried out. For example, the laser beam L ₃ can be selected instead of the laser beam L ₂ and the laser processing step can be executed in the same manner as described above.
At this time, since the laser beam L ₃ has a different wavelength, it is diffracted by a diffraction pattern different from that of the laser beam L ₂ , but the diffraction direction D coincident with the regular reflection direction R of the on-state micromirror 7 b has a wavelength λ. ₂ and λ ₃ are common, and even in the case of the laser beam L ₃ , the laser beam L ₃ is emitted with the highest diffraction efficiency in the diffraction direction D by the micro mirror 7 b in the on state.
Therefore, according to the change of the diffraction direction based on the difference in wavelength, for example, without instructing to move the installation position of the irradiation optical system 20, simply instructing the laser oscillator 1 to switch the wavelength, Laser processing can be realized with similar diffraction efficiency.

  In addition, according to the present embodiment, since the tilt stages 4 and 5 are provided, even when the tilt angle of the micro mirror 7b of the micro mirror array 7 is constant, light with high diffraction efficiency is incident on the irradiation optical system 20. Can do. Therefore, the apparatus can be configured with a standard product without using a custom-made product in which the inclination angle of the micromirror 7b is changed, so that there is an advantage that a simple and inexpensive apparatus can be obtained.

Next, a modification of this embodiment will be described.
FIG. 6 is a schematic explanatory diagram for explaining a schematic configuration of a laser processing apparatus according to a modification of the embodiment of the present invention.
In the laser processing apparatus 110 of this modification, the modulated light generating unit 30 in which the tilt stage 5 of the laser processing apparatus 100 of the above embodiment is deleted and the relative position of the micromirror array 7 with respect to the laser oscillator 1 is fixed. And the modulated light generator 30 is rotatably held by the tilt stage 4. The position of the micromirror array 7 is a position where the optical axes of the laser beams L ₂ and L ₃ are incident on the approximate center of the reference reflecting surface 7a at a constant incident angle.
The following briefly describes the differences from the above embodiment.

According to the configuration of this modified example, this corresponds to the case where the tilt stages 4 and 5 are rotated in synchronization in the above embodiment. Since the tilt stage 4 can be rotated in the biaxial direction, the diffraction direction D and the optical axis 202 can be matched.
In this case, since the tilt stage 5 can be deleted, there is an advantage that an inexpensive apparatus can be configured with a simple configuration.

In the above description, the example in which the laser beam is composed of two harmonics has been described, but the number of harmonics may be three or more. In that case, the diffraction direction common to each can be set as follows.
That is, a plurality of harmonics, the _{u k} harmonic of n (n ≧ 3) _{(u k} are different from each other integers, k = 1, 2, ..., n) when the common to the plurality of wavelengths as a diffraction direction of diffraction _{orders, (u k · m x,} u k · m y) follows _(where, m x, _{m y} are integers) may be set in a direction that is.

In the above description, an example in which laser light has a plurality of wavelengths by harmonics of the fundamental wavelength has been described. However, the plurality of wavelengths is not limited to harmonics. For example, laser beams having a plurality of wavelengths emitted from different light sources may be used.
The plurality of wavelengths is preferably an exact integer ratio, but may be an approximately integer ratio as long as the change in diffraction efficiency is within an allowable range. In this case, there is no common diffraction direction, but there are diffraction directions close to each other. Accordingly, by making the optical axis of the irradiation optical system coincide with one of these diffraction directions close to each other or the average diffraction direction thereof, the same effects as those in the case of the integer ratio are provided.
The degree of the substantially integer ratio is set according to the degree of coincidence of the diffraction directions. For example, m _x, when m _y increases, the diffraction direction in proportion to the deviation of the integer ratio is shifted, it is preferable to approach a more exact integer ratio. On the other hand, m _x, if m _y is relatively small, be offset from exact integer ratio, the amount of deviation of the diffraction direction is reduced, it is possible to obtain good diffraction efficiency. The amount of deviation in the diffraction direction is preferably set to be smaller than at least the rear side angular aperture of the irradiation optical system 20.

In this case, when the wavelengths of the plurality of laser light sources are n (n ≧ 2) λ _uk (u _k is an integer different from each other, k = 1, 2,..., N), lambda _uk is set to be substantially (lambda / _{u k),} as a diffraction direction common to the wavelength, diffraction _{orders, (u k · m x,} u k · m y) follows (where, m _x, m _y is to set the direction of diffraction of the integer).
For example, by using a nitrogen laser (wavelength λ ₂ = 337.1 nm) and a second harmonic of a YAG laser (λ ₃ = 532 nm), the two wavelength ratios λ ₂ : λ ₃ are approximately an integer ratio 5: It can be configured to be 8.

In the above description, the example using two of the second and third harmonics as the harmonic has been described, but three or more harmonics may be used as necessary. Further, the order of harmonics may be selected at random.
In that case, a plurality of harmonics, the _{u k} harmonic of n (n ≧ 2) _{(u k} is different integers, k = 1, 2, ..., n) to the time, common to a plurality of wavelengths as a diffraction direction, each of the diffraction _{orders, (u k · m x,} u k · m y) follows _(where, m x, _{m y} are integers) may be set in a direction that is.

In the above description, the example in which the diffraction direction that is common to or substantially coincides with all of the plurality of wavelengths and the optical axis of the irradiation optical system are matched is described. However, depending on the processing conditions, only a part of the plurality of wavelengths is used. It may not be used. In that case, depending on the wavelength used for processing by the rotation mechanism control unit, a direction in which the diffraction directions thereof substantially coincide with each other is calculated, and a control signal may be sent to match the optical axis of the irradiation optical system. Good.
Further, only one type of wavelength may be used for processing, and in that case, an appropriate diffraction direction and the optical axis of the irradiation optical system can be matched.

  In the above description, the rotation mechanism control unit calculates the rotation position of the rotation mechanism and sends a control signal. However, depending on the wavelength of all laser beams of the laser light source or a combination thereof, The positional relationship may be calculated in advance, and the calculation result may be stored as a data table, for example.

It is a schematic explanatory view for explaining a schematic configuration of a laser processing apparatus according to an embodiment of the present invention. It is typical optical path explanatory drawing for demonstrating the optical path of the spatial modulation element vicinity used for the laser processing apparatus which concerns on embodiment of this invention. It is an angle distribution diagram for demonstrating the diffraction direction after rotation control of the diffracted light radiate | emitted from the spatial modulation element of the laser processing apparatus which concerns on embodiment of this invention. It is typical optical path explanatory drawing for demonstrating an example of the optical axis setting of the laser processing method which concerns on embodiment of this invention. It is a schematic explanatory view for explaining an initial state of the laser processing apparatus according to the embodiment of the present invention. It is typical explanatory drawing for demonstrating schematic structure of the laser processing apparatus of the modification of embodiment of this invention. It is an angle distribution figure for demonstrating an example of the angle distribution of the diffracted light in the laser processing apparatus which can switch a wavelength.

Explanation of symbols

1 Laser oscillator (laser light source)
4, 5 Inclined stage (rotating mechanism)
4a, 5a Stage driver 7, 601 Micromirror array (spatial modulation element)
7a Reference reflecting surface 7b Micro mirror (deflection element)
DESCRIPTION OF SYMBOLS 11 Imaging lens 14 Objective lens 15 Work piece 16 Control part 20 Irradiation optical system (modulation light irradiation optical system)
100, 110 Laser processing device 150A Image signal 151 Processing pattern data 202 Optical axis (optical axis of modulated light irradiation optical system)
203 rear angle aperture 610, 620, 630 0-order diffracted light 611, 621, 631 1-order diffracted light 622, 632 second-order diffracted light 633 3-order diffracted light _L 2, _{L 3} the laser beam _{L M} modulated light N normal

Claims (5)

A laser light source for generating laser light;
In order to spatially modulate the laser beam, a spatial modulation element in which a plurality of deflection elements that can be deflected in at least two directions are regularly arranged;
A modulated light irradiation optical system for irradiating a workpiece with modulated light formed by reflecting the laser light by the spatial modulation element;
A rotation mechanism that varies the inclination of the incident optical axis of the laser light incident on the spatial modulation element and the inclination of the spatial modulation element with respect to the optical axis of the modulated light irradiation optical system;
A laser processing apparatus characterized in that an output angle of the modulated light incident on the modulated light irradiation optical system with respect to the spatial modulation element is variable by the rotating mechanism. The turning mechanism is
The laser processing apparatus according to claim 1, further comprising a mechanism that rotates to change an inclination of the laser light source with respect to the spatial modulation element.   The diffraction direction of the modulated light is calculated from the rotation position of the rotation mechanism and the wavelength of the laser beam, and the rotation mechanism is adjusted so that the diffraction direction substantially coincides with the optical axis of the modulated light irradiation optical system. The laser processing apparatus according to claim 1, further comprising a rotation mechanism control unit for driving. The laser light source is generated so that two or more different wavelengths of laser light can be switched,
4. The laser according to claim 3, wherein the rotation mechanism control unit substantially matches an optical axis of the modulated light irradiation optical system with a diffraction direction common to the wavelength of each of the laser beams. Processing equipment. The spatial modulation element is
5. The laser according to claim 1, wherein the laser is a micromirror array including a plurality of micromirrors that switch the tilt angle and deflect the laser light in at least two directions as the plurality of deflection elements. Processing equipment.

Images