JP5064778B2 - 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 laser processing (repair processing) of defects on a liquid crystal substrate, a semiconductor substrate, a printed circuit board, and the like using a reflective spatial modulation element.

Conventionally, for example, in a manufacturing process of a liquid crystal display device (LCD), various inspections are performed on a glass substrate processed in a photolithography process. As a result of this inspection, when a defective portion is detected in the resist pattern or etching pattern formed on the glass substrate, laser processing is performed to remove the defective portion by irradiating the defective portion with laser light using a laser processing apparatus, In many cases, so-called repair processing is performed.
As an apparatus that can be used as such a laser processing apparatus, Patent Document 1 discloses that a laser beam emitted from a laser oscillator such as an excimer laser is made uniform in intensity distribution on a cross section using a beam homogeneous optical system such as a homogenizer. A laser processing apparatus is described in which a transfer dot pattern is formed on a workpiece by a microlens mirror array to perform laser processing.
In Patent Document 2, shape data of a defective portion is extracted from defect image data acquired by imaging a defective portion on a glass substrate, and each micromirror of a DMD (Digital Micro mirror Device) unit is extracted according to the shape data. A repair method and an apparatus for irradiating the defect portion with the angle control at high speed and making the cross-sectional shape of the laser beam reflected by these micromirrors substantially coincide with the shape of the defect portion are described.
Japanese Patent Application No. 8-174242 (FIG. 1) Japanese Patent Laying-Open No. 2005-103581 (FIG. 1)

However, the conventional laser processing apparatus as described above has the following problems.
In the techniques described in Patent Documents 1 and 2, in order to process a two-dimensional pattern by spatially modulating a laser beam corresponding to a defect shape, a reflective spatial modulation element including a microlens mirror array and a DMD, respectively. Is used. For this reason, depending on the energy of the laser beam, these micromirrors may deteriorate. For example, the surface of the micromirrors arranged in an array constituting the DMD is covered with an aluminum thin film. When these micromirrors are irradiated with laser light and used for a long time, the surface of the aluminum thin film on the micromirror surface is reduced. There is a problem that the reflectivity gradually decreases and eventually deteriorates until the thin film is removed, and the laser beam may not be reflected.

  The present invention has been made in view of the above problems, and in a laser processing apparatus using a reflective spatial modulation element, the deterioration of the reflective surface of the reflective spatial modulation element can be delayed to improve the life of the apparatus. An object is to provide a laser processing apparatus.

In order to solve the above problems, a laser processing apparatus of the present invention is a laser processing apparatus that performs laser processing on a workpiece based on processing data representing processing shape information in a processable region on a processing surface. In order to spatially modulate the laser light emitted from the laser light source and the laser light source, the reflective spatial modulation element having a plurality of micromirrors provided in the modulation region with variable tilt angles, and the reflective space An imaging optical system that forms an image of the laser beam reflected in a certain direction by the modulation element in the workable region, and disposed on an optical path between the laser light source and the reflective spatial modulation element, laser emitted from the laser light source beam, and the irradiation area changing section for varying the size and position of the irradiation area on the modulation region, and the irradiation area setting unit for setting the size and position of the irradiation region, the Addition Corresponding to the data, a spatial modulation data generating unit that generates spatial modulation data for selecting a micromirror that reflects the laser beam toward the certain direction, and the spatial modulation data generated by the spatial modulation data generation unit Based on the spatial modulation element drive control unit that switches the tilt angle of each micromirror of the reflective spatial modulation element, the irradiation region setting unit to the spatial modulation data generated by the spatial modulation data generation unit based on, that have to be able to set the size and position of the irradiation area.
According to the present invention, the laser beam emitted from the laser light source is irradiated onto the reflective spatial modulation element, the light reflected in a certain direction by the micromirror is incident on the imaging optical system, and the surface to be processed is An image is formed in the processable area of the. Thereby, laser processing based on the processing data is performed. At this time, an irradiation area changing unit is arranged between the laser light source and the reflective spatial modulation element so that the size and position of the irradiation area on the modulation area can be varied. Accordingly, by changing the size and position of the irradiation region by the irradiation region setting unit and narrowing the irradiation region with respect to the modulation region, the energy of the laser light irradiated to the reflective spatial modulation element can be reduced. it can.
The size and position of the defect that appears in the processable area changes as the processing conditions and workpiece change, so the laser beam irradiation area will be equalized over time, and each time laser processing is performed Compared to the case where all the micromirrors of the reflective spatial modulation element are irradiated with laser light, on average, damage to each micromirror by the laser light can be reduced.

In addition , the irradiation area setting unit can set the size and position of the irradiation area based on the spatial modulation data generated by the spatial modulation data generation unit. Since the irradiation area can be set efficiently based on the spatial modulation data generated based on the above, the energy of the laser light irradiated to the reflective spatial modulation element can be reduced without impairing the processing efficiency Can do.

  According to the laser processing apparatus of the present invention, in the laser processing apparatus using the reflective spatial modulation element, the irradiation area changing unit can narrow the irradiation area of the laser beam to the reflective spatial modulation element. There is an effect that the deterioration of the reflection surface of the spatial modulation element can be delayed and the life of the apparatus can be improved.

  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.

[First Embodiment]
A laser processing apparatus according to the first embodiment of the present invention will be described.
FIG. 1 is a schematic explanatory view in a cross section including an optical axis showing a schematic configuration of the laser processing apparatus according to the first embodiment of the present invention. FIGS. 2A, 2B, and 2C show the irradiation area changing unit and the reflective spatial modulation element used in the laser processing apparatus according to the first embodiment of the present invention on the reference axis side of the reflective spatial modulation element. It is the model explanatory drawing seen from.

The laser processing apparatus 100 of this embodiment is a laser processing apparatus suitable for performing repair processing, which is laser processing, by irradiating a workpiece with laser light. For example, in a workpiece in which a circuit pattern or the like is formed on a substrate in a photolithography processing step, such as a glass substrate of an LCD (liquid crystal display) or a semiconductor wafer substrate, for example, a defective portion such as a short circuit of a wiring portion or protrusion of a photoresist This can be suitably used for repair processing such as removing a defective portion when a stagnation is detected.
As shown in FIG. 1, the schematic configuration of the laser processing apparatus 100 includes a laser light source 30, a spatial modulation element 6 (reflection type spatial modulation element), a variable mask 5 (irradiation area changing unit), and an imaging lens 7 (imaging optics). System), objective lens 10 (imaging optical system), observation light source 14, observation imaging lens 12, imaging element 13, image processing unit 23, device control unit 21, user interface 27, and the like. In FIG. 1, reference numeral 11 denotes a substrate that is a workpiece, and reference numeral 11 a denotes a processing surface of the substrate 11.

The laser light source 30 is a light source for repair processing that emits laser light 31 b toward the spatial modulation element 6. In the present embodiment, a configuration including a laser oscillator 1, a coupling lens 2, a fiber 3, and a projection lens 4 is employed.
The laser oscillator 1 outputs laser light 31a having an appropriate wavelength and output in order to remove defects on the substrate 11. For example, a YAG laser capable of pulse oscillation can be preferably used. The oscillation wavelength may be switched between a plurality of oscillation wavelengths according to the repair target.
The laser oscillator 1 is electrically connected to a laser oscillator control unit 26 that controls light emission of the laser oscillator 1 in accordance with a control signal from the apparatus control unit 21.

The laser oscillator control unit 26 performs, for example, a light emission wavelength, an oscillation mode such as pulse oscillation, lighting on / off control, or the like according to the laser irradiation condition stored in advance in the apparatus control unit 21 or input by the user interface 27. be able to. Although not shown in particular, in order to adjust the light intensity of the laser beam 31a, a neutral density filter or the like can be switched on the exit side of the laser oscillator 1 so that the switching can be controlled by the laser oscillator control unit 26. Good.
In the present embodiment, an example will be described in which laser light 31a having a constant pulse is emitted with a constant light intensity by one processing. This single light emission is called a laser shot.

  Since the laser light 31a output from the laser oscillator 1 has a Gaussian distribution in general, the light amount is condensed by the coupling lens 2 arranged on the optical path of the laser light 31a in this embodiment. It is optically coupled to one end 3a. Then, by passing the fiber 3 and emitting it from the other end 3b of the fiber 3, the laser light 31b having a uniform light quantity distribution can be emitted.

  The projection lens 4 has an arrangement in which the fiber end surface 3a and the reference plane of the spatial modulation element 6 are conjugated, and the projection magnification is such that the image of the fiber end surface 3a can be irradiated to the entire modulation region of the spatial modulation element 6. The set lens or lens group.

The spatial modulation element 6 is a reflective spatial modulation element that spatially modulates the laser light 31 b projected from the projection lens 4 of the laser light source 30. In this embodiment, a DMD (Digital Micro mirror Device) which is a micro mirror array is employed. That is, as shown in FIG. 2 (a), a plurality of micromirrors 6a are arranged in a rectangular modulation region of long side W × short side H, and their reflecting surfaces are aligned in a reference plane. The micromirrors 6a can be selectively tilted in two different directions by a control signal from the spatial modulation element drive control unit 24 that is arranged in a row and electrically connected to the spatial modulation element 6. Yes.
Each micromirror 6a is rotated by, for example, + 12 ° from the reference plane in the on state by an electrostatic electric field generated according to a control signal from the spatial modulation element drive control unit 24, and −12 from the reference plane in the off state. ° Rotated. Hereinafter, light reflected by the on-state micromirror 6a is referred to as on-light, and light reflected by the off-state micromirror 6a is referred to as off-light.
The position of each micromirror 6a can be represented by (m, n), for example, with column number m in the long side direction and row number n in the short side direction (m, n is an integer of 0 or more).

  The variable mask 5 is disposed on the optical path between the laser light source 30 and the spatial modulation element 6, and the size of the irradiation area of the laser light 31 b emitted from the laser light source 30 on the modulation area of the spatial modulation element 6. And an irradiation area changing unit for changing the position. In this embodiment, it consists of movable masks 5 a and 5 b provided close to the spatial modulation element 6.

As shown in FIG. 2A, the movable masks 5a and 5b are opposed to L-shaped end portions L _a and L _b extending along the short side direction and the long side direction of the modulation region of the spatial modulation element 6, respectively. And a rectangular opening is formed between them. The movable masks 5a and 5b are slidably overlapped, and can be independently moved two-dimensionally on the modulation area of the spatial modulation element 6 by the mask control unit 25 (see FIG. 1).
For example, FIG. 2A shows a state where the end portions L _a and L _b of the movable masks 5 a and 5 _b are moved so as to be substantially aligned with the outer periphery of the modulation region. In this case, the counter has been end L _a, while the L _b, the irradiation area P ₁ by the opening that contains the entire modulation area size of W × H is formed.
Also, FIG. 2 (b), (c), respectively, from the state of FIG. 2 (a), the movable masks 5a, move 5b to the opposite direction, the opening area is small rectangular than the irradiation area _{P 1} Illustrated is a state in which irradiation regions P ₂ and P ₃ are formed and formed at different positions on the modulation region.
Irradiation area P ₂ in FIG. 2 (b) is an example of forming the corners of the modulation area including the origin O provided on the modulation area of the spatial modulation element 6, the irradiation region P ₃ shown in FIG. 2 (c) is an example of moving the irradiation area P ₂ in the vicinity of the corners of the origin O and facing modulation region.

The mask control unit 25 can use an appropriate biaxial moving mechanism. The movement control of the movable masks 5a and 5b is performed using, for example, the position coordinates of the spatial modulation element 6 with respect to the origin O. For example, the position coordinates of the points Q _a and Q _b at the opposite corners of the corresponding end portions L _a and L _b are calculated from the size and position information of the irradiation area sent from the apparatus control unit 21. Thus, the moving amount and moving direction of the movable masks 5a and 5b are set.

The imaging lens 7 and the objective lens 10 are an imaging optical system that forms an image of the ON light 32 that is spatially modulated by the spatial modulation element 6 and reflected in a certain direction on the processing surface 11 a of the substrate 11. The imaging lens 7 is disposed on the spatial modulation element 6 side, and the objective lens 10 is disposed on the substrate 11 side. As a result, the reference plane on which the micromirrors 6a of the spatial modulation element 6 are arranged and the processed surface 11a are in a conjugate relationship. In this embodiment, the board | substrate 11 is mounted horizontally on the mounting base 17, and the position is being fixed.
The projection magnification of this imaging optical system is appropriately set according to the required processing accuracy on the processing surface 11a. For example, an image having a size of W × H of the entire modulation region is set to be projected on the processing surface 11a to a size of W ′ × H ′ at a magnification β. That is, a region in the range of W ′ × H ′ on the processing surface 11a is a workable region.
Here, the NA of the imaging lens 7 satisfies a resolution necessary for processing, and has a size such that light reflected as off-light (not shown) does not enter.

On the optical path between the imaging lens 7 and the objective lens 10, semi-transparent mirrors 9 and 8 are inserted in order from the objective lens 10 side.
The semi-transparent mirror 9 is formed of a half mirror having a reflective transmittance characteristic that transmits the ON light 32 and reflects a part of the observation light 33 emitted from the observation light source 14, and the reflected observation light 33 is coupled. They are arranged in a positional relationship where they can enter the objective lens 10 along the optical axis of the image optical system.
The observation light source 14 is a light source that generates observation light 33 for illuminating the processable region on the processing surface 11a in order to determine a processing shape and confirm a processing result. For example, an appropriate light source such as a xenon lamp or LED that generates visible light can be used.

The semi-transparent mirror 8 reflects the part of the observation light 33 reflected by the processing surface 11a out of the light that transmits the ON light 32, passes through the semi-transparent mirror 9 from the substrate 11 side, and travels on the optical path. It consists of a half mirror having transmittance characteristics.
The reflection transmittance characteristics of the semi-transparent mirrors 9 and 8 may be provided with wavelength characteristics. In this case, the transmittance is preferably high with respect to the wavelength of the on-light 32, and preferably about 100%. In this way, since the light amount loss in the imaging optical system is reduced, the light amount of the laser light 31b can be further reduced. That is, the amount of light applied to the spatial modulation element 6 is further reduced.
Further, it may be configured such that it can be retracted from the optical path by raising or moving at the time of laser light irradiation.

The observation imaging lens 12 is a lens or a lens group that is arranged on the optical path of the observation light 33 reflected by the semi-transparent mirror 8 and forms an image on the imaging surface of the imaging element 13.
The image pickup device 13 photoelectrically converts an image formed on the image pickup surface, and includes, for example, a CCD.
The image signal photoelectrically converted by the image sensor 13 is sent to an image processing unit 23 electrically connected to the image sensor 13.

The image processing unit 23 performs appropriate image processing such as noise processing and luminance correction, for example, from the image signal sent from the image sensor 13 to acquire image data of the processing surface 11a. This image data is enlarged and displayed on a monitor that constitutes a part of the user interface 27, for example.
Further, the image processing unit 23 extracts defects from the image data, generates processing shape information for removing the defects as processing data, and sends the processing data to the apparatus control unit 21.
For this defect extraction process, any known defect extraction algorithm may be used. For example, the brightness difference between the acquired image data and the pattern image data of the normal processed surface 11a stored in advance is taken, and the defect is extracted from data obtained by binarizing the difference data with a certain threshold value. be able to.

In the present embodiment, as shown in FIG. 1, the end portion of the laser light source 30 on the projection lens 4 side of the fiber 3, the spatial modulation element 6, the variable mask 5, the imaging lens 7, the semi-transparent mirrors 8 and 9, and the objective lens 10, the observation light source 14, the observation imaging lens 12, and the image sensor 13 are integrally held by a holding member (not shown) such as a housing while maintaining their relative positions to form a processing head 15. Yes.
The machining head 15 is held by a machining head drive unit 22 made of, for example, an XY moving stage so that the position of the machining head 15 can be moved at least along a plane parallel to the surface 11a.
The processing head drive unit 22 is electrically connected to the apparatus control unit 21 and can move the position of the processing head 15 according to a control signal from the apparatus control unit 21. As a result, the surface 11a to be processed is moved relative to the optical axis of the imaging optical system that projects the ON light 32, and the processable region is moved. Further, the illumination range of the observation light 33 sharing the optical axis is also moved together with the processable region.

The apparatus control unit 21 is electrically connected to the processing head drive unit 22, the image processing unit 23, the spatial modulation element drive control unit 24, the mask control unit 25, the laser oscillator control unit 26, and the user interface 27, and Communication is performed between them, data and control signals are transmitted and received, and necessary arithmetic processing is performed to perform overall control of the laser processing apparatus 100.
In this embodiment, the device controller 21 uses a computer composed of a CPU, a memory, an input / output unit, an external storage device, and the like, and programs created corresponding to the respective control functions and calculation functions are used. It is realized by executing.
The apparatus configuration of the image processing unit 23 may use dedicated hardware. However, in the present embodiment, the image processing unit 23 is realized by executing an image processing program by a computer configuring the apparatus control unit 21.

  The function of the device control unit 21 is based on the spatial modulation data generation unit that generates spatial modulation data for selecting a micromirror that reflects the laser light in a certain direction corresponding to the processing data, and the spatial modulation data. Thus, the function of an irradiation area setting unit for setting the size and position of the irradiation area is included.

  The user interface 27 provides input / output means of the device control unit 21. In the present embodiment, although not particularly illustrated, an operation unit for an operator to input instruction information for performing operation control of the laser processing apparatus 100, for example, an operation button, a keyboard, a mouse, or the apparatus control unit 21. It includes a monitor that displays the processed image information, various numerical values, and character information so that the operator can check it.

Next, the operation of the laser processing apparatus 100 will be described.
FIG. 3 is a flowchart for explaining the operation of the laser processing apparatus according to the first embodiment of the present invention. FIGS. 4A and 4B are schematic diagrams showing an example of the positional relationship between defects generated in the workable area and the modulation area of the reflective spatial modulation element. FIGS. 5A and 5B are schematic views for explaining an irradiation region setting method in the laser processing apparatus according to the first embodiment of the present invention.

The laser processing apparatus 100 is initialized when the power is turned on through the user interface 27. And the board | substrate 11 is mounted as a workpiece on the mounting base 17, and laser processing is performed as follows.
First, in step S1, an image of a processable area of the processing surface 11a is acquired. That is, the observation light source 14 is turned on and the observation light 33 is generated. Part of the observation light 33 is reflected by the semi-transparent mirror 9, and this reflected light is condensed by the objective lens 10 to illuminate the processable region on the processing surface 11a.
The reflected light 34 reflected by the work surface 11 a is collected by the objective lens 10, and a part of the light passes through the semi-transparent mirror 9. A part of the light is further reflected by the semi-transparent mirror 8 and guided to the observation imaging lens 12. The reflected light 34 incident on the observation imaging lens 12 is imaged on the imaging surface of the imaging element 13.
The image sensor 13 photoelectrically converts the image of the imaged surface 11a to be processed and sends it to the image processor 23 as an image signal. In this way, an image of the processable area of the processing surface 11a is acquired.
This image is displayed on the monitor of the user interface 27 after performing processing such as noise removal and luminance correction as necessary. Further, it is stored in the apparatus control unit 21 as two-dimensional image data.

Next, in step S2, the image processing unit 23 performs defect extraction from the image data acquired in step S1. Then, from the image data of the defect extracted here, processing data representing the position of the defect and processing shape information is generated and sent to the apparatus control unit 21.
Since the processing data and the image data acquired in step S1 have a projection magnification of β of the imaging optical system, the position coordinates on the processable area are multiplied by 1 / β to modulate the spatial modulation element 6. This can correspond to the position of the region.
After acquiring the machining data, the apparatus control unit 21 generates spatial modulation data that turns on all the micromirrors 6a corresponding to the position of the machining data and turns off the other micromirrors 6a. In the present embodiment, for example, the spatial modulation data is generated as table data corresponding to the numerical values of the on state being 1 and the off state being 0 corresponding to the position (m, n) of each micromirror 6a.

Next, in step S <b> 3, the device control unit 21 calls the past accumulated laser irradiation amount data stored in the external storage device of the device control unit 21 into the memory. This accumulated laser irradiation amount data is obtained by adding the laser irradiation amount data corresponding to the minute mirror 6a in the irradiation region set in the next step S4 in the past laser processing for each minute mirror 6a.
The accumulated laser irradiation amount data has an initial value of 0, and the updated data continues to be stored in the external storage device until it is forcibly reset, for example, when the spatial modulation element 6 is replaced.
In the present embodiment, the laser irradiation amount data to be added is for counting laser shots. For example, 1 is added when set to the irradiation region once.

Note that, for example, when the pulse width and light intensity for each laser shot are changed depending on the environment in which the laser processing apparatus 100 is used and the processing target, the accumulated laser irradiation amount data matches the actual laser irradiation light amount. If necessary, the laser irradiation amount data may be weighted.
In addition, when the deterioration rate of the micromirror 6a is influenced by repeated thermal stress or the like, and when it depends on the number of irradiations rather than the cumulative value of the laser irradiation light amount, the laser irradiation light amount for each laser shot is Even if it changes, it is only necessary to store the cumulative number of irradiations.
As described above, as the accumulated laser irradiation amount data, a considerable amount of laser irradiation light amount represented by various numerical values based on the number of laser shots can be set as necessary. Therefore, it is not limited to the exact laser irradiation light quantity.

Next, in step S4, an irradiation area is set based on the spatial modulation data and the accumulated laser irradiation amount data.
In the present embodiment, the irradiation region is formed by shielding the laser beam 31b with the variable mask 5 serving as the irradiation region changing unit. As shown in FIG. 1, a laser beam 31 b oscillated by a laser oscillator 1, passed through a coupling lens 2 and a fiber 3 and having a uniform light amount distribution is irradiated to a range including all the modulation regions of the spatial modulation element 6. .
Since the variable mask 5 is disposed between the laser light source 30 and the spatial modulation element 6, the laser beam 31b is only light that enters the range of the opening of the variable mask 5 determined by the positional relationship between the movable masks 5a and 5b. Reaches the spatial modulation element 6.
For example, if the state movable mask 5a, 5b is fully opened as shown in FIG. 2 (a), the irradiation area P ₁ corresponds to the whole of the modulation area. In the states of FIGS. 2B and 2C, the laser beam 31b is irradiated to a part of the modulation area as in the irradiation areas P ₂ and P ₃ .

  In order to delay deterioration with time of the micromirror 6a, it is preferable that the irradiation region has a rectangular opening as small as possible including a range where the spatial modulation data is 1. Since the variable mask 5 of the present embodiment can continuously change the size and position of the rectangular opening, an irradiation region can be formed by an optimal rectangular opening as necessary.

For example, as shown in FIG. 4A, when the defect positions 40 and 41 where the spatial modulation data is set to 1 are spaced apart at opposite diagonal positions of the modulation area, the irradiation shown in the figure is at a minimum. it is necessary to select a region P ₄ or more ranges. Such a minimum irradiation area range is calculated by the device control unit 21 by calculating spatial modulation data.
In addition, after calculating such a minimum irradiation area range, for example, an irradiation error may be taken into consideration, and a wider area or the entire modulation area such as the irradiation area P ₁ may be set. . Note that the area may be divided into two when priority is given to the lifetime without considering the reduction in throughput.
On the other hand, as shown in FIG. 4B, when there is only one defect position 42 in the vicinity of the origin O, the irradiation area P ₅ surrounded by the defect position 42 or a larger irradiation area P ₂ is set. do it.

  Since the appearance position, size, number, etc. of defects generally differ from processing to processing, even if the irradiation area is set as narrow as possible in this way, the entire modulation area is set to the irradiation area for each processing. The average amount of laser irradiation to the minute mirror 6a is reduced. Therefore, the lifetime of the spatial modulation element 6 can be extended.

  In the present embodiment, in order to extend the life more efficiently, if there is a position where the accumulated laser irradiation amount data is more equalized with reference to the accumulated laser irradiation amount data called in step S3, The irradiation area moved to such a position is set.

For simplicity, in the following, as in the example of FIG. 4 (b), the irradiation area that is set once as described above is an area P _2, a case was the overall size of 1/6 Think. As a result of referring to the cumulative laser irradiation amount data, cumulative laser irradiation amount in the region P ₂ is a larger than the other regions.
In this case, setting the irradiation area in the region P _2, as compared with other regions, the deterioration of the micro mirror 6a regions P ₂ becomes intense.
Therefore, in the present embodiment, for example, as shown in FIG. 5A, appropriate representative values, for example, an average value and a maximum value, of the accumulated laser irradiation amount data of each of the six regions M1 to M6 on the modulation region. And the like, and the region with the smallest representative value is reset as the irradiation region. For example, the area M6 is set. In this case, the irradiation area is moved from the area M1 to the area M6.
When the representative value of the accumulated laser irradiation amount data in each region is the same, any region may be set. For example, the region P ₂ (M1) may remain as it is. In that case, the process proceeds to steps S5 and S6 without performing the next operation.
In this way, as the laser processing is repeated, the accumulated laser irradiation amount data for each micromirror 6a is equalized.

In this case, since there is no defect on the processing surface 11a corresponding to the irradiation region M6, as shown in FIG. 5B, the position of the spatial modulation element 6 is changed to a processable region on the processing surface 11a. On the other hand, the region M6 of the spatial modulation element 6 is made to correspond to the corresponding position 420 of the defect by parallel translation in the illustrated oblique direction. This movement is expressed by a vector O′O from the point O ′ to the point O using the corner point O ′ on the origin O side of the region M6.
In accordance with this, the spatial modulation data in the region M1 is converted in the direction opposite to the movement of the spatial modulation element 6, that is, by moving by the vector OO ′ and arranged in the region M6. In FIG.5 (b), the area | region of the code | symbol 60 respond | corresponds to the position of the processable area | region of the to-be-processed surface 11a.

Next, in steps S5 and S6, the setting conditions of the apparatus are controlled according to the irradiation region finally set in step S4. The execution order of these two steps is arbitrary.
In step S5, the movable masks 5a and 5b are moved relative to the moving spatial modulation element 6, and a control signal is transmitted to the mask control unit 25 so that an opening is formed in the irradiation region M6 in FIG. To do. Thereby, the variable mask 5 is moved to the positional relationship as shown in FIG.

In step S6, the relative position of the spatial modulation element 6 with respect to the processable region on the processing surface 11a is moved by moving the processing head 15 by the processing head driving unit 22. This movement is executed by sending a control signal for movement corresponding to the vector O′O obtained in step S4 from the apparatus control unit 21 to the machining head driving unit 22 in consideration of the magnification β of the imaging optical system. Is done.
That is, in this embodiment, the machining head drive unit 22 relatively moves the workpiece in the opposite direction in response to the parallel movement of the spatial modulation data and the irradiation region by the spatial modulation data generation unit and the irradiation region setting unit. Relative movement means.
When steps S5 and S6 are completed, step S7 is executed.

In step S7, a control signal corresponding to a predetermined laser irradiation condition is sent from the apparatus control unit 21 to the laser oscillator control unit 26, and a laser shot for emitting the laser beam 31a from the laser oscillator 1 is performed.
The laser beam 31a is optically coupled to the end surface 3a of the fiber 3 by the coupling lens 2, is transmitted through the fiber 3, and is emitted as the laser beam 31b from the end surface 3b in a state where the light quantity distribution is uniformized.
The laser light 31b is projected by the projection lens 4 toward the spatial modulation element 6, shielded by the variable mask 5, and only the laser light 31b that passes through the irradiation region reaches the micromirror 6a.
The off-light (not shown) with the tilt angle turned off is reflected outside the range of NA of the imaging lens 7 and only the on-light 32 reflected by the micromirror 6a with the tilt angle turned on. Is incident on the imaging lens 7. The ON light 32 passes through the semi-transparent mirrors 8 and 9 and is imaged on the processing surface 11 a by the objective lens 10.
As a result, an image of the modulation area by the ON light 32 based on the spatial modulation data corresponding to the processing data is projected onto the processing surface 11a, and the ON light 32 is irradiated to the defect on the processing surface 11a, thereby removing the defect. Is done.
Thus, one laser processing is completed.
Further, the accumulated laser irradiation amount data in the external storage device is updated in correspondence with the irradiation region in the laser processing.
Then, if necessary, the above process is repeated, and if there is an unremoved portion, the laser processing is performed again, or the processable region is moved to perform laser processing of other portions.

As described above, according to the laser processing apparatus 100, the laser beam irradiation area to the micromirror 6a can be narrowed to a necessary range by the variable mask 5 at one time of laser processing. Accordingly, it is possible to irradiate the laser beam to the portion of the micromirror 6a where the cumulative laser irradiation amount is small, so that the deterioration of the micromirror 6a of the spatial modulation element 6 can be delayed and the life of the apparatus can be improved.
The reflective spatial modulation element may be configured to be movable in two dimensions parallel to the reference plane, and may be a fixed mask that can change only the irradiation size instead of the movable mask. If control is always performed so that the regions M1 to M6 of the spatial modulation element 6 are positioned on the optical axis, the processing head relative position setting in step S6 can be omitted. Therefore, it is not necessary to move a heavy processing head, and throughput can be improved.

[Second Embodiment]
A laser processing apparatus according to the second embodiment of the present invention will be described.
FIG. 6A is a schematic perspective view showing a schematic configuration of an irradiation region changing unit of the laser processing apparatus according to the second embodiment of the present invention. FIG. 6B is a schematic explanatory diagram illustrating the correspondence relationship between the irradiation region and the modulation region corresponding to the irradiation region changing unit in FIG.

  The laser processing apparatus 110 according to the present embodiment includes a variable mask 50 instead of the variable mask 5 of the laser processing apparatus 100 according to the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment.

As shown in FIG. 6A, the variable mask 50 is a surface parallel to the modulation area in a range covering the entire modulation area of the spatial modulation element 6 between the projection lens 4 of the laser light source 30 and the spatial modulation element 6. The disk 50a has a hole and is held by a stepping motor or the like so as to be rotatable and movable at an appropriate rotation angle.
A plurality of holes according to the size and position of the irradiation region to be set are provided in the circumferential direction in the holed disc 50a. In the present embodiment, when seven holes m _{1 to} m ₇ are provided and the disk with holes 50a stops at an appropriate rotation angle, as shown in FIG. 6B, the region on the spatial modulation element 6 Openings corresponding to M1 to M7 are formed.
Here, the holes m _{1 to} m ₆ have positions and sizes that equally divide the modulation region of the spatial modulation element 6 into six, and the hole m ₇ is an opening over the entire modulation region.
Further, the positions and sizes of the holes m _{1 to} m ₆ that equally divide the modulation region into 6 are examples, and have appropriate sizes according to the size and appearance rate of defects to be processed. It can be configured.

According to such a laser processing apparatus 110, when the spatial modulation data corresponding to the processing data obtained from the defect position falls within the areas M1 to M6 in step S4 of FIG. 3, one of the areas is selected. First, the irradiation area is set, and the same operation as in the first embodiment is performed.
On the other hand, when the spatial modulation data does not fit in the areas M1 to M6, the area M7 is set as an irradiation area. In this case, without comparing the accumulated laser irradiation amount data and moving the irradiation region, the process proceeds to the next steps S5 and S6, and laser processing can be similarly performed.

According to such a laser processing apparatus 110, the irradiation area of the laser beam to the micromirror 6a can be narrowed by the variable mask 50 in accordance with the size and position of the defect during one laser processing, According to the past irradiation history, it is possible to irradiate a portion of the micromirror 6a where the accumulated laser irradiation amount is small with laser light, thereby delaying the degradation of the micromirror 6a of the spatial modulation element 6 and improving the device life. Can do.
For example, as described above, assuming that the illumination area divides the modulation area into 6 equal parts, and the probability that a defect covers a plurality of areas is 0, the 6 areas can be equally used. As a result, a life that is six times that of the case where the entire modulation region is always irradiated can be obtained.

  In the above description, an example in which a rectangular irradiation region is set by the irradiation region changing unit has been described. However, the shape of the irradiation region is not limited to a rectangle, and an appropriate shape is adopted. Can do.

  In the description of the second embodiment, the description has been given of the example in which the plurality of openings of the irradiation region changing unit are the one that opens in the entire modulation region and the one that divides the modulation region into six equal parts. You may make it further provide the opening which divides | segments a modulation area | region by the magnitude | size between two, for example, what divides into 2 parts, what divides into 3 parts, etc. In this case, even if the defect location spans between the six equally divided openings, the probability that the defect will fit in one of the two equally divided (three equally divided) openings increases, so the amount of laser light irradiation can be further reduced. , Life can be extended.

  In the description of the second embodiment, the variable mask 50 is rotated and moved to change the irradiation area. However, the variable mask 50 may be moved two-dimensionally.

  In the above description, the relative moving means is described as an example in which the processing head is moved. However, the work table is moved by holding the mounting table 17 so as to be movable by an XY moving stage or the like. Also good.

In the above description, the relative movement means is provided so that even if the irradiation area on the spatial modulation element is moved, it is possible to irradiate a laser beam to a certain area on the workpiece. When not moving, the relative moving means may not be provided.
Even if the irradiation area is not moved, if the appearance position of the defect in the workable area changes, a different irradiation area is set on the modulation area accordingly. Even with only the configuration to be set, the average amount of laser irradiation to each micromirror is reduced, and the lifetime of the spatial modulation element can be extended.

  In the above description, the irradiation region setting unit has been described as an example in which the size and position of the irradiation region are set based on the spatial modulation data. The size and position of the irradiation area may be manually set by an operation input regardless of the spatial modulation data. For example, the operator may be able to set the irradiation region in a range including the defective portion by observing the monitor of the user interface 27 while confirming the defective portion on the monitor and inputting an image from the monitor.

  In the above description, an example in which an imaging unit that images a processing surface is provided in order to acquire processing data has been described. However, for example, defect information is acquired by another inspection apparatus and the processing data is acquired. Is not required to include an imaging means for acquiring the processed data.

  Further, in the above description, in order to make the light quantity of the laser light emitted from the laser light source uniform, the example of the configuration that transmits the fiber 3 has been described. However, the means for making the laser light uniform includes other optical elements, For example, a configuration using a homogenizer having various configurations such as a fly-eye lens, a diffractive element, an aspheric lens, and a kaleido type rod may be used.

It is a schematic explanatory drawing in the cross section containing the optical axis which shows schematic structure of the laser processing apparatus which concerns on the 1st Embodiment of this invention. It is the model explanatory drawing which looked at the irradiation area change part and reflection type spatial modulation element which are used for the laser processing apparatus which concerns on the 1st Embodiment of this invention from the reference-axis side of a reflection type spatial modulation element. It is a flowchart explaining operation | movement of the laser processing apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the example of the positional relationship with respect to the modulation area | region of the reflection type spatial modulation element of the defect which generate | occur | produced in the processable area | region. It is a schematic diagram explaining the setting method of the irradiation area | region in the laser processing apparatus which concerns on the 1st Embodiment of this invention. The typical perspective view which shows schematic structure of the irradiation area | region change part of the laser processing apparatus which concerns on the 2nd Embodiment of this invention, and the model explaining the correspondence of the irradiation area | region and modulation area corresponding to an irradiation area change part It is explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillator 3 Fiber 4 Projection lens 5, 50 Variable mask (irradiation area change part)
6 Spatial modulator (reflective spatial modulator)
6a Micro mirror 7 Imaging lens (imaging optical system)
10 Objective lens (imaging optical system)
11 Substrate (Workpiece)
11a Work surface 15 Processing head 17 Mounting table 21 Device control unit 22 Processing head drive unit (relative movement means)
23 Image processing unit 24 Spatial modulation element drive control unit 25 Mask control unit 26 Laser oscillator control unit 30 Laser light sources 31a and 31b Laser light 32 On light 100 and 110 Laser processing apparatus

Claims (3)

A laser processing apparatus for laser processing a workpiece based on processing data representing processing shape information within a processable area on a processing surface,
A laser light source;
In order to spatially modulate the laser light emitted from the laser light source, a reflective spatial modulation element having a plurality of micromirrors provided in the modulation region with variable tilt angles;
An imaging optical system that forms an image of the laser beam reflected in a predetermined direction by the reflective spatial modulation element in the workable region;
Irradiation area change that is arranged on the optical path between the laser light source and the reflective spatial modulation element and changes the size and position of the irradiation area of the laser light emitted from the laser light source on the modulation area And
An irradiation area setting unit for setting the size and position of the irradiation area ;
Corresponding to the processing data, a spatial modulation data generating unit that generates spatial modulation data for selecting a micromirror that reflects the laser light in the fixed direction;
A spatial modulation element drive control unit that switches an inclination angle of each micromirror of the reflective spatial modulation element based on the spatial modulation data generated by the spatial modulation data generation unit;
The irradiation area setting unit, wherein on the basis of the spatial modulation data generated by the spatial modulation data generating unit, a laser processing device which is characterized that you have to be able to set the size and position of the irradiation area. A relative movement means for relatively moving the workpiece in a direction intersecting the optical axis of the imaging optical system;
The spatial modulation data generation unit and the irradiation region setting unit are respectively generated and set to a position obtained by translating the spatial modulation data and the irradiation region, which are generated and set, from the position on the modulation region corresponding to the processing data. Configured to be generated and configured,
The relative movement means relatively moves the workpiece in the reverse direction in response to the parallel movement of the spatial modulation data and the irradiation region by the spatial modulation data generation unit and the irradiation region setting unit. The laser processing apparatus according to claim 1 , wherein a workpiece at a position corresponding to the processing data can be laser-processed by a laser beam from the irradiated irradiation region. The spatial modulation data generation unit and the irradiation region setting unit are
The parallel movement is set so that the accumulated data for the minute mirror is equalized based on accumulated data of a considerable amount of laser irradiation light amount for each minute mirror of the spatial modulation element. Item 3. The laser processing apparatus according to Item 2 .

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