JP2007229786A - Laser machining system and focussing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser machining system and a focussing control method, capable of achieving focussing with high precision. <P>SOLUTION: The laser machining system where the focus of laser light emitted to a machining object through an image forming lens is controlled to perform laser machining, is provided with: a mask 58 having a slit for focussing; an image pick-up means 54 where a machining mark machined by the laser light emitted to the machining object 19 through the slit and the image forming lens 14 is photographed; an image selection control means 55 where, based on image data on a plurality of the machining marks photographed by the image pick-up means and the image data on a machining mark as a preset standard, specified image data are selected; and a control means 57 where, based on the image data on the machining mark selected by the image selection control means, the distance between the machining object and the image forming lens is regulated so as to perform focussing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus and a focusing control method, and more particularly to a laser processing apparatus and a focusing control method for realizing highly accurate focusing.

Conventionally, a processing target such as a semiconductor is processed using a CO ₂ (carbon dioxide) laser, a YAG laser, an excimer laser, or the like. Further, laser light is mainly used for processing such as welding, cutting, and drilling using a high energy density with respect to irradiation of a processing surface of a workpiece.

  Another method is to set the beam spot diameter to a certain extent (1 to several tens of millimeters) using a mask, and anneal (surface modification) to improve the surface function of the material while melting only a limited area of the processed surface. Quality) is also used for processing. For example, in a processing object such as an annealed substrate on which crystals or the like are continuously grown, laser processing is performed by forming an image of the laser light that has passed through a mask and a high-resolution imaging lens on the processing object.

  Here, the resolution indicates the slope (inclination) of the edge in the intensity distribution of the laser beam formed on the surface of the object to be processed by passing through the slit formed in the mask and the imaging lens. Moreover, the shorter the distance of the slope portion, the higher the resolution. Note that the depth of focus of irradiation on the object to be processed in the annealing process is shallow.

  Here, in order to perform laser processing with high accuracy, focusing is important. Here, as a conventional technique related to focusing, laser processing is performed on an object to be processed in advance for focusing, and an operator takes out the object to be processed and confirms it with a microscope or the like, thereby focusing on an appropriate position. There is a technique to do. However, the above-described method takes a great burden and time on the operator, and a difference occurs for each operator, so that focusing accuracy is lacking.

  Therefore, as another method, for example, a method of using a non-contact sensor (non-contact displacement meter) to adjust the substrate irradiation surface to a specified height is disclosed (for example, see Patent Document 1). As another method, there is a method in which an intensity distribution measuring device represented by a laser profiler or the like is installed on a processing table on which a processing target is placed, and a focal position is determined using the laser profiler.

  Here, the conventional laser processing apparatus in the above-mentioned content is demonstrated using figures. FIG. 8 is a diagram illustrating a configuration example of a conventional laser processing apparatus. A laser processing apparatus 10 shown in FIG. 8 includes a laser oscillator 11, a reflection mirror 12, a mask 13, an imaging lens 14, a processing stage 15, a processing stage driving unit 16, a profiler 17, and a control unit 18. It is comprised so that it may have.

The laser oscillator 11 emits laser light to the reflection mirror 12 according to a control signal from the control means 18. Here, as the laser light, for example, an XeCl excimer laser having 1 pulse energy of 1 J, an oscillation frequency of 300 Hz, and a wavelength of 308 nm can be used. The type of laser light is not particularly limited. For example, a KrF excimer laser having a wavelength of 248 nm, a KrCl excimer laser having a wavelength of 222 nm, a YAG laser, a CO ₂ laser, or the like can be used.

  The reflection mirror 12 reflects the laser beam emitted from the laser oscillator 11 toward the mask 13. The mask 13 has an opening (slit) for making the laser beam a predetermined shape. Here, the type of the mask is not particularly limited, and for example, a chrome mask that is inexpensive and can be manufactured with a short delivery time can be used.

  The laser beam that has passed through the slit of the mask 13 is applied to the imaging lens 14. The imaging lens 14 is an imaging lens for focusing the laser beam so that the intensity of the light applied to the workpiece 19 is imaged on the processing surface with a predetermined intensity. Further, the imaging lens 14 irradiates the object 19 with the focused laser beam.

  The processing stage 15 is a stage for moving the processing object 19 to a predetermined position. For example, the processing object 19 is fixed on the processing stage 15 by vacuum suction or the like.

  Further, the processing stage driving means 16 makes the processing stage 15 perpendicular to the optical axis of the laser beam shown in FIG. 8 (X and Y axis directions) or optical axis direction (Z axis) according to a control signal from the control means 18. Direction) and a predetermined inclination angle θ direction with respect to the optical axis, etc., thereby moving the workpiece 19 to a predetermined position. Further, for example, by performing movement at a predetermined speed in a predetermined direction during laser irradiation, an annealing process or the like can be performed on the processing surface of the processing object.

  The profiler 17 is an intensity distribution measuring device that is installed on the side wall of the processing stage 15 and measures the intensity of the laser light applied to the processing object 19. By having the profiler 17, it is possible to measure the inclination (resolution) of the end of the light intensity. The control unit 18 adjusts the optical axis (Z-axis) direction of the processing stage driving unit 16 based on the measurement result obtained from the profiler 17 and performs focusing on the processing object 19. Further, the control means 18 controls the emission timing of the laser beam in the laser oscillator 11 and the drive timing of the processing stage driving means 16 for driving the processing stage 15 at the time of processing.

<About resolution>
Here, the above-described resolution will be described with reference to the drawings. FIG. 9 is a diagram illustrating an example of the resolution. As shown in FIG. 9, the mask 13 is provided with a slit 21 as an opening for irradiating the workpiece 19 with a laser beam having a predetermined shape. Since the slit 21 has a predetermined slit width, the laser light applied to the workpiece 19 is ideally rectangular as shown by the light intensity distribution 22 and the processing mark 23.

  However, in order to actually perform the laser processing, it is necessary to focus the laser light by the imaging lens 14 and form an image on the surface of the processing target as described above. As a result, the light intensity distribution 24 and the light shown in FIG. It looks like a machining mark 25. At this time, as shown in the light intensity distribution 24, an inclination (inclination) occurs at the end, and this slope represents the resolution. Further, since the intensity distribution of the laser beam has a slope, the actual processing mark 25 becomes wider than the ideal processing mark 23 as shown in FIG.

The slope (resolution) is determined corresponding to the imaging lens. In general, the slope required for good machining is very small in a section from a position of 20% to a position of 90% with respect to a section of the entire slope at one end. As described above, conventionally, focusing is performed by the slope (resolution) measured by the profiler.
JP 2001-44136 A

  However, when a profiler is used, there is a possibility that an error occurs in focusing due to the thickness of the workpiece. More specifically, as shown in the conventional profiler installation example in FIG. 10, the profiler 17 is usually installed at the height of the processing stage 15 in the laser processing apparatus 10 as shown in FIG. 8. In some cases, a fixing member 31 is interposed between the processing stage 15 and the profiler 17.

  That is, since the thickness of the workpiece 19 varies depending on the type of the workpiece, it is difficult to always align the position of the profiler 17 with the position of the surface of the workpiece 19. Furthermore, for example, when thermal deformation due to laser light irradiation occurs in the fixing member 31 that fixes the profiler 17, an error occurs in the relative position between the workpiece 19 and the profiler 17. Therefore, an accurate measurement result cannot be obtained from the profiler 17 from the above state, and thus high-precision focusing cannot be performed.

  Further, in the case of the technique using the non-contact sensor described in Patent Document 1, focusing can be performed without directly processing the processing target, but in order to perform focusing with higher accuracy, it is actually necessary. It is preferable to confirm by processing the object to be processed.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a laser processing apparatus and a focusing control method for realizing highly accurate focusing.

  In order to achieve the above-described object, the present invention provides a focusing slit in a laser processing apparatus that performs laser processing by controlling the focus of laser light that passes through an imaging lens and is irradiated on a processing object. A mask having imaging means for photographing a processing mark processed by a laser beam that has passed through the slit and the imaging lens and applied to the processing object, and a plurality of processing marks photographed by the imaging means. Based on the image data and the image data of the processing mark as a reference set in advance, based on the image selection control means for selecting specific image data, and the image data of the processing mark selected by the image selection control means And control means for controlling to adjust the distance between the object to be processed and the imaging lens to perform focusing. Thereby, highly accurate focusing can be realized. Therefore, highly accurate laser processing can be realized.

  Further, the control means may change the distance between the object to be processed and the imaging lens, and generate a plurality of processing marks on the object to be processed by the laser light that has passed through the slit and the image forming lens. preferable. As a result, a plurality of machining traces can be actually generated, and an optimum machining trace can be selected from them. Therefore, highly accurate focusing can be realized.

  Further, the image selection control means includes correlation coefficient calculation means for calculating a correlation coefficient between each image data of the plurality of processing marks and the image data of the reference processing marks, and the image selection control means includes the correlation Based on the calculation result obtained by the number calculating means, it is preferable to select the image data of the processing trace closest to the reference processing trace image data. Thereby, it is possible to select the image data of the processing mark closest to the reference processing image data as a reference more accurately. Therefore, highly accurate focusing can be realized.

  Furthermore, display means for displaying the image data of the plurality of processing marks and the image data of the processing marks serving as the reference, and input means for receiving selection information of specific image data from the image data of the plurality of processing marks Preferably, the image selection control means selects image data of a processing mark from selection information obtained by the input means. Thus, the operator can select an optimum machining trace quickly and easily by referring to the machining trace rather than directly viewing the machining trace of the workpiece.

  Furthermore, the slit forms a slit width so that the intensity distribution of the laser beam irradiated to the object to be processed through the imaging lens is only a slope portion determined by the imaging lens. Is preferred. Thereby, by using the slit width in the vicinity of the resolution, it is possible to notice the change in the processing mark with respect to the change in the focal position. Therefore, highly accurate focusing can be realized by performing focusing based on the processing marks.

  Furthermore, it is preferable to form the slit in a mask in which a slit for actual processing is formed. Thereby, it is possible to prevent focusing errors caused by the thickness of the slit, the material, and the like, which are caused by separating the mask having the slit for focusing and the mask having the slit for processing.

  Furthermore, it is preferable to have a mask stage driving means for moving the mask and replacing the slit for processing and the slit for focusing. Thereby, the error which arises by thickness, a raw material, etc. can be prevented by using the same mask.

  The present invention also relates to a focusing control method in a laser processing apparatus that performs laser processing by controlling a focus of laser light that passes through an imaging lens and is irradiated on a processing target, and the imaging lens and the processing target A focusing processing step for performing processing for a plurality of focusing by changing the distance of the object, a photographing step for photographing each processing mark processed by the focusing processing step, and the processing photographed by the photographing step An image selection step for selecting specific image data based on the image data of the trace and the image data of the processing trace serving as a reference set in advance, and based on the image data of the processing trace obtained by the image selection step And a focusing control step for controlling to adjust the distance between the object to be processed and the imaging lens. The features. Thereby, highly accurate focusing can be realized. Therefore, highly accurate laser processing can be realized.

  And a correlation coefficient calculating step of calculating a correlation coefficient between each image data of the plurality of processing marks and the reference processing mark image data, and the image selection step includes the correlation coefficient It is preferable to select the image data of the processing trace closest to the reference processing trace image data based on the calculation result obtained in the calculation step. Thereby, it is possible to select the image data of the processing mark closest to the reference processing image data as a reference more accurately. Therefore, highly accurate focusing can be realized.

  And a display step for displaying the image data of the plurality of processing marks and the image data of the processing marks as a reference, and a selection information input step for receiving selection information of image data from an operator. Preferably, the step selects image data of a specific processing mark from a plurality of processing mark image data based on the selection information obtained in the selection information input step. Thus, the operator can select an optimum machining trace quickly and easily by referring to the machining trace rather than directly viewing the machining trace of the workpiece.

  Further, the focusing processing step uses the mask on which the processing slit for processing the processing object and the slit for focusing are formed, and the slit for focusing is formed on the laser beam. It is preferable that the focusing process is performed at the light incident position. Thereby, the error which arises by thickness, a raw material, etc. can be prevented by using the same mask.

  According to the present invention, highly accurate focusing can be realized.

<Outline of the present invention>
The present invention forms a focusing slit having a slit width so as to obtain a light intensity distribution having only a resolution determined by an imaging lens (including the entire optical system) as a mask, and the focusing slit. A plurality of processings are performed on the processing target by changing the distance (position in the optical axis (Z-axis) direction) between the lens and the processing target via, and the processing result (processing trace) is confirmed.

  Here, the above-mentioned content is demonstrated using figures. FIG. 1 is a diagram illustrating an example of the outline of the present invention. In the present invention, as shown in FIG. 1A, a processing slit 42 and a focusing slit 43 that are used when the mask 41 is actually processed are formed. The focusing slit 43 has such a slit width that the intensity distribution of the laser light that passes through the slit and the imaging lens and is irradiated onto the processing surface of the processing object is formed only from the slope (resolution). Is done.

  Further, laser processing is performed by irradiating the processing target with laser light while changing the distance between the imaging lens and the processing target with the laser light that has passed through the focusing slit 43. By changing the distance, different slopes (tilts) such as intensity distributions 44-1, 44-2, 44-3,... Are obtained as shown in FIG. Thereby, as shown in FIG.1 (c), it becomes a respectively different shape like the process trace 45-1, 45-2, ....

  Moreover, there is a threshold value for the energy density that leaves a processing mark on the surface of the processing object. The total amount of energy (triangle area) of each intensity distribution 44 shown in FIG. 1B is the same, and when the slope is sleeping, it falls rapidly below the threshold. Thus, by using the slit width corresponding to the resolution, it is possible to notice the change of the processing mark with respect to the change of the focal position. Therefore, highly accurate focusing can be realized by performing focusing based on the processing marks.

  Further, when confirming which processing trace is in focus, the operator may check it visually, but a camera comprising a CCD (Charge Coupled Devices) image sensor that acquires the processing trace as image data. (Image pickup means) By comparing the image data of the processing trace photographed by the camera with the image data of the processing trace serving as a preset reference acquired in a state of being in focus in advance, A desired machining mark can be positioned at the machined Z-axis position. Thereby, highly accurate focusing can be realized. Therefore, highly accurate laser processing can be realized.

  Next, a preferred embodiment of the laser processing apparatus and the focusing control method according to the present invention will be described with reference to the drawings. In the first embodiment described below, the same reference numerals are used for the same components as those of the laser processing apparatus 10 shown in FIG. 1, and the description thereof is omitted.

<First Embodiment>
FIG. 2 is a diagram illustrating a configuration example of the laser processing apparatus according to the first embodiment. 2 includes a laser oscillator 11, a reflection mirror 12, an imaging lens 14, a processing stage 15, a processing stage driving device 16, a mask stage 51, a mask stage driving means 52, and a height. The sensor 53, the camera 54, the image selection control means 55, the correlation coefficient calculation means 56, and the control means 57 are comprised.

The laser processing apparatus 50 according to the first embodiment places the mask 58 on the mask stage 51 and moves the mask 58 in the XY axis direction (perpendicular to the optical axis) by the mask stage driving unit 52. Here, the mask 58 and the mask stage 51 will be described with reference to the drawings. FIG. 3 is a diagram for explaining an example of the mask and the mask stage in the present embodiment. In FIG. 3, the mask 58 and the mask stage 51 are separated from each other, but the mask 58 is fixed on the mask stage 51 by vacuum suction or the like during use.
As shown in FIG. 3, the mask 58 has a processing slit 61 for processing the processing object 19 and a focusing slit 62.

  The focusing slit 62 has a slit width based on the resolution (slope) determined by the imaging lens 14 used as described above. Therefore, when performing focusing, the mask stage driving means 52 moves the mask stage 51 in the direction perpendicular to the optical axis (XY direction) by the control signal from the control means 57, and the focusing slit 62 is moved to the laser. The focusing processing in the present invention is performed at the light incident position. Further, after the focusing is completed, the mask stage driving unit 52 moves the mask stage 51 in the X and Y directions by the control signal from the control unit 57, positions the processing slit 61 at the incident position of the laser beam, and actually processes it. Processing to the object 19 is performed.

  In the present embodiment, a mask using only the focusing slit and a mask provided only with the processing slit may be prepared, and the respective masks may be changed during focusing and processing. However, since there is a possibility that an error occurs in the focal position during processing depending on the thickness of the slit, the material, and the like, it is preferable to form the same slit on the same mask as the focusing slit and the processing slit as shown in FIG.

  Further, as shown in FIG. 3, the mask stage 51 is provided with an opening (mask stage opening 63) having a predetermined size in order to prevent attenuation of the laser light that has passed through the slit and has a predetermined shape. Yes. The mask stage opening 63 is formed in a rectangular shape, but is not limited to this in the present embodiment, and may be, for example, a circle or a polygon.

  Further, the laser processing apparatus 50 shown in FIG. 2 is provided with a height sensor 53 as height measuring means. The height sensor 53 measures the distance from the surface of the workpiece 19 and outputs the measurement result to the control means 57. Thereby, the distance between the imaging lens 14 and the workpiece 19 can be obtained with high accuracy. Therefore, highly accurate laser processing can be performed on various processing objects having different thicknesses.

  The camera 54 as an imaging unit has a CCD imaging device, and photographs a processing mark obtained by irradiating the processing object 19 with laser light that has passed through the focusing slit 62 and the imaging lens 14. The photographed image data is output to the image selection control means 55. In addition, although processing to the processing target 19 for performing the focusing may use a processing target different from the processing target to be actually processed, because there is a variation in the thickness of the processing target, It is preferable to perform processing for focusing on an object to be actually processed. In this case, focusing processing is performed in a region other than the processing region in which actual processing is performed on the processing target.

  The image selection control means 55 acquires image data of a plurality of actually processed machining traces obtained from the camera 54 in response to a control signal from the control means 57, and the image data of the machining traces that are set in advance as the reference data. A close processing mark is selected and the result is output to the control means 57. It should be noted that the image data of the reference processing mark is accumulated in the image selection control means 55.

  Here, FIG. 4 is a diagram illustrating an example of a comparison between a preset machining mark and a machining mark formed by changing a position in a different height direction (Z-axis direction). As shown in FIG. 4, the machining trace closest to the machining trace 71 machined in advance in focus is selected from the machining traces 72-1 to 72-5 actually processed and acquired by the camera 54.

  Further, the correlation coefficient calculating means 56, according to an instruction from the image selection control means 55, obtains the processing trace image data obtained by the actual focusing process and the preset processing trace image data as a reference. A correlation coefficient (correlation value) that is an index of how much they match is calculated. Specifically, for example, each of a plurality of image data captured by the camera 54 is compared with reference image data in units of pixels, and a correlation coefficient is obtained by comparing how much they match. A specific example of calculating the correlation coefficient in the correlation coefficient calculation means 56 will be described later.

  The correlation coefficient calculation unit 56 outputs the calculation result to the image selection control unit 55. The image selection control unit 55 can more accurately select the image data of the closest processing trace based on the calculation result obtained from the correlation coefficient calculation unit 56.

  The control means 57 inputs distance information from the surface of the workpiece 19 from the height sensor 53. Further, the control means 57 is a laser light oscillation timing in the laser oscillator 11, a driving timing in the mask stage driving means 52, a driving timing in the processing stage driving means 16, an image selection control means 55 and an image selection timing for performing focusing control. And the control signal is output to each component to control the entire laser processing apparatus 50.

<Focusing control procedure>
Here, the focusing control processing procedure in the laser processing apparatus of the present invention will be described using a flowchart. FIG. 5 is a flowchart showing an example of a focusing control processing procedure in the present invention.

  When performing the focusing, first, the mask is moved so that the laser beam is incident on the focusing slit (S01). Next, the processing target placed on the processing stage 15 is changed by changing the height (optical axis, Z-axis) of the processing stage 15, that is, the distance between the imaging lens 14 and the processing target 19 until a predetermined number is reached. Processing for focusing is performed on the object 19 (S02).

  During the processing in S02, the irradiation position is moved by the processing stage every time processing is performed so that the same position of the processing target 19 is not irradiated with laser light. Further, information such as which height position (distance) and what processing has been performed is managed by the control means 57. In the above-described embodiment, there is no restriction on how much the height of the processing stage 15 is changed. For example, the processing for focusing can be performed by changing the height of the processing stage every 5 μm.

  Next, the processing trace processed into the processing object 19 by S02 is image | photographed with a camera (imaging means), and the image data of each processing trace is acquired (S03). When acquiring the image data, the processing trace image data is acquired in the processed order, and identification information for identifying the processing trace is added in advance so that the processing trace can be identified when selecting the processing trace. May be. Further, the image data of the processing mark acquired in S03 is compared with the image data of the processing mark serving as a reference that has been processed in advance in focus, and the closest processing mark is selected (S04).

  When selecting the closest processing trace, the correlation coefficient, which is information indicating the degree of coincidence, is calculated using the processing trace image data acquired in S03 and the reference processing trace image data. The closest processing trace may be selected from the calculated result. Further, as shown in a second embodiment to be described later, each image data described above is displayed on display means such as a monitor, and the selected image data selection information selected by the operator referring to the displayed image data. The machining trace may be selected based on selection information obtained from an input unit that accepts.

  Next, the processing at the time of focusing processing managed by the control means 57 based on the information of the processing mark selected in S04 (for example, information indicating the number of processing marks or identification information of the processing mark). With reference to the conditions, the processing stage is set to the height (distance) when the selected processing trace is processed (S05). Further, in order to make the laser beam enter the actual processing slit 61 formed in the mask 58, the mask is moved (S06), and the focusing control process is ended.

  The focus control process described above is performed at the timing of starting the laser processing apparatus 50 (for example, every morning, every week, etc.), the timing of changing the mask due to deterioration, or the like.

<Method of calculating correlation coefficient (correlation value)>
Here, an example of the above-described correlation coefficient calculation method will be described. FIG. 6 is a diagram for explaining an example of a correlation coefficient calculation method. As shown in FIG. 6, an image P (M, N) of a processing mark serving as a reference that is set in advance and a partial image (actual image) of an image B (X, Y) obtained by photographing the processing mark obtained by focusing processing. The image of the machining trace of ( _ii ) B _ij (M, N) and the cross-correlation coefficient C _ij is obtained by the calculation of the following equation (1), and a coordinate value whose value is larger than a preset specified value is obtained. Output.

なお、上述した（１）式において、Ｃ_ｉｊは、常に−１≦Ｃ_ｉｊ≦１の値となり、特にＣ_ｉｊ＝１の場合は、基準となる加工痕の画像Ｐ（Ｍ，Ｎ）と、実際の加工痕の画像Ｂ_ｉｊ（Ｍ，Ｎ）とが完全に一致していることを示す。

In the above-described equation (1), C _ij always has a value of −1 ≦ C _ij ≦ 1, and particularly when C _ij = 1, a reference image P (M, N) of the processing trace, It shows that the image B _ij (M, N) of the actual processing mark completely matches.

  Therefore, among the plurality of correlation coefficients obtained from each of the actual image data of the processed traces and the reference processed trace image data, the image of the processed trace that has the closest correlation coefficient to 1 The data can be selected as the image data of the processing trace closest to the reference processing image data (focused image data).

In addition, as the specified value described above, for example, a value obtained by multiplying C _ij by 10,000 can be specified as a parameter.

  As described above, high-precision focusing can be realized by the first embodiment. Specifically, a slit corresponding to the lens resolution for focusing is provided in the mask, the laser beam that has passed through the slit and the imaging lens is irradiated to the processing object, and the processing trace is used directly. Focus can be sought. Further, by using the correlation coefficient obtained by the image processing, it is possible to select the image data of the processing trace that is closest to the reference processing image data. Thereby, highly accurate focusing can be realized. Therefore, highly accurate laser processing can be realized.

  In the first embodiment described above, when performing the focusing, the processing trace is selected based on the calculation result of the correlation coefficient by the correlation coefficient calculating unit 56. For example, the processing processed for the focusing is performed. Display means for displaying the image data of the trace and the image data of the machining trace set in advance, and an input for the operator to select specific image data from the image data of each machining trace displayed on the display means Means may be provided. Thus, the operator can select an optimum machining trace quickly and easily by referring to the machining trace rather than directly viewing the machining trace of the workpiece. Here, the above-described content will be described as a second embodiment with reference to the drawings. In the second embodiment described below, the same reference numerals are used for the same components as those of the laser processing apparatus 50 shown in FIG. 2, and the description thereof is omitted.

<Second Embodiment>
FIG. 7 is a diagram illustrating a configuration example of a laser processing apparatus according to the second embodiment. The laser processing apparatus 80 shown in FIG. 7 includes display means 81 for causing the operator to select a processing mark instead of the correlation coefficient calculation means 56 as compared with the laser processing apparatus 50 in the first embodiment shown in FIG. Input means 82 is provided.

  The image selection control means 83 acquires image data of a plurality of processing marks for focusing processed on the processing object 19 by photographing with the camera 54, and the acquired image data is displayed on the display means 81 including a monitor or the like. Output to. At this time, the image selection control unit 83 causes the display unit 81 to display image data of a plurality of processing marks processed at different heights for focusing and image data of processing marks set in advance. At this time, the image selection control unit 83 may perform various image processing such as enlarged display, reduced display, array display, and overlay display when displaying each image data on the display unit 81.

  Further, the image selection control means 83 refers to the image data displayed on the display means 81 by the operator, and inputs such as a keyboard and a mouse for receiving selection information for selecting specific image data from the image data of a plurality of processing marks. From the selection information obtained by the means 82, information (identification information etc.) relating to a specific machining mark is output to the control means 57. The control means 57 outputs a control signal to the processing stage driving means 16 from this information, and moves the processing stage 15 to a predetermined position. Thereby, highly accurate focusing can be realized.

  As described above, according to the second embodiment, the operator can quickly and easily refer to the machining trace and select the optimum machining trace, rather than directly viewing the machining trace of the workpiece. it can. Thereby, highly accurate focusing can be realized. Therefore, highly accurate laser processing can be realized.

  In addition, embodiment in this invention is not limited to embodiment mentioned above, For example, you may comprise the laser processing apparatus which combined the 1st and 2nd embodiment mentioned above. Further, in the above-described embodiment, the processing stage is moved when performing the focusing. However, the present invention is not limited to this, and for example, the lens driving means for driving the lens (imaging lens) is provided. The control unit may drive the lens during focusing.

  In addition, an execution program that can cause a general-purpose computer to execute the processing in each of the image selection control unit, the correlation coefficient calculation unit, the display unit, and the input unit described above is generated. The above-described focusing control process can be realized by installing in the computer. Moreover, the execution program installed in the computer may be provided by a recording medium such as a CD-ROM, or may be provided by downloading from a server or the like via a communication network.

  As described above, according to the present invention, highly accurate focusing can be realized. Specifically, a slit corresponding to the lens resolution for focusing is provided in the mask, the laser beam that has passed through the slit and the imaging lens is irradiated to the processing object, and the processing trace is used directly. Focus can be sought. Further, by using the correlation coefficient obtained by the image processing, it is possible to select the image data of the processing trace that is closest to the reference processing image data. Thereby, highly accurate focusing can be realized. Therefore, highly accurate laser processing can be realized.

  The laser processing in the present invention can also be applied to processing such as drilling, grooving, annealing, and welding.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be changed.

It is a figure of an example for demonstrating the outline | summary of this invention. It is a figure which shows the example of 1 structure of the laser processing apparatus in 1st this embodiment. It is a figure for demonstrating an example of the mask and mask stage in this embodiment. It is a figure which shows an example of the comparison with the processing trace set beforehand and the processing trace processed by changing the position of a different height direction (Z-axis direction). It is a flowchart which shows an example of the focus control processing procedure in this invention. It is a figure for demonstrating an example of the calculation method of a correlation coefficient. It is a figure which shows one structural example of the laser processing apparatus in 2nd this embodiment. It is a figure which shows the example of 1 structure of the conventional laser processing apparatus. It is a figure of an example for demonstrating the resolution. It is a figure which shows the example of installation of the conventional profiler.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,50,80 Laser processing apparatus 11 Laser oscillator 12 Reflection mirror 13,41,58 Mask 14 Imaging lens 15 Processing stage 16 Processing stage drive means 17 Profiler 18,57 Control means 21 Slit 22,24,44 Intensity distribution 23,25 45, 71, 72 Processing trace 31 Fixing member 42, 61 Processing slit 43, 62 Focusing slit 51 Mask stage 52 Mask stage driving means 53 Height sensor 54 Camera 55, 83 Image selection control means 56 Correlation coefficient calculation means 63 Mask stage opening 81 Display means 82 Output means

Claims (11)

In a laser processing apparatus that performs laser processing by controlling the focal point of laser light that passes through an imaging lens and is irradiated onto a processing target,
A mask having a slit for focusing;
Imaging means for photographing a processing mark processed by a laser beam irradiated to the processing object through the slit and the imaging lens;
Image selection control means for selecting specific image data based on image data of a plurality of processing marks taken by the imaging means and image data of processing marks serving as a reference set in advance;
And control means for controlling to adjust the distance between the object to be processed and the imaging lens based on the image data of the processing mark selected by the image selection control means. Laser processing equipment. The control means includes
The processing object and the imaging lens are changed, and a plurality of processing marks are generated on the processing object by laser light that has passed through the slit and the imaging lens. The laser processing apparatus as described. Correlation coefficient calculating means for calculating a correlation coefficient between each of the plurality of processing trace image data and the reference processing trace image data,
2. The image selection control means, based on a calculation result obtained by the correlation coefficient calculation means, selects image data of a processing trace that is closest to the reference processing trace image data. Or the laser processing apparatus of 2. Display means for displaying the image data of the plurality of processing marks and the image data of the processing marks serving as the reference;
Input means for receiving selection information in which specific image data is selected from the image data of the plurality of processing marks,
The laser processing apparatus according to claim 1, wherein the image selection control unit selects image data of a processing mark from selection information obtained by the input unit.   The slit has a slit width so that an intensity distribution of a laser beam irradiated to the object to be processed through the imaging lens is only a slope portion determined by the imaging lens. The laser processing apparatus according to any one of claims 1 to 4.   The laser processing apparatus according to claim 1, wherein the slit is formed in a mask in which an actual processing slit is formed.   The laser processing apparatus according to claim 6, further comprising a mask stage driving unit configured to move the mask and replace the slit for processing and the slit for focusing. In a focus control method in a laser processing apparatus that performs laser processing by controlling the focus of laser light that passes through an imaging lens and is irradiated onto a processing object,
A focusing process step of performing a plurality of focusing processes by changing a distance between the imaging lens and the processing object;
A photographing step of photographing each processing mark processed by the focusing processing step;
An image selection step for selecting specific image data based on the image data of the processing mark imaged in the imaging step and the image data of the processing mark serving as a reference set in advance;
A focusing control step for controlling to adjust the distance between the object to be processed and the imaging lens based on the image data of the processing mark obtained by the image selection step. Focusing control method. A correlation coefficient calculating step of calculating a correlation coefficient between each of the plurality of processing trace image data and the reference processing trace image data;
9. The image selection step selects image data of a processing trace that is closest to the reference processing trace image data based on a calculation result obtained by the correlation coefficient calculation step. The focusing control method described. A display step of displaying the image data of the plurality of processing marks and the image data of the processing marks serving as the reference;
A selection information input step for receiving selection information of image data from an operator;
The focus according to claim 8, wherein the image selection step selects image data of a specific processing mark from a plurality of processing mark image data based on the selection information obtained in the selection information input step. Alignment control method. The focusing processing step includes
The focusing slit is positioned at the incident position of the laser beam by using a mask in which a slit for processing and a slit for focusing are formed to process the workpiece. The focusing control method according to any one of claims 8 to 10, characterized in that processing is performed.

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