JP2009006339A - Laser beam machining apparatus and laser beam machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus capable of performing high quality machining. <P>SOLUTION: The laser beam machining apparatus includes: a laser beam source for emitting a laser beam; a stage for holding a workpiece; an optical system including a first optical deflector for scanning the laser beam emitted from the laser beam source in such a manner that its incident position moves on the workpiece held on the stage; a second optical deflector; an imaging device that, through the first and second optical deflectors, images a part of the region on the surface of the workpiece held on the stage; and a controller for controlling the second optical deflector so that a region different from the incident position of the laser beam in the surface of the workpiece held on the stage is imaged by the imaging device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that performs processing by irradiating a workpiece with a laser beam, and a laser processing method.

  In the patterning of the substrate, the laser beam scanning method includes moving the substrate using an XY stage and changing the incident position of the laser beam on the substrate, and changing the laser beam emission direction using, for example, a galvano scanner. There is a method of changing the incident position of the laser beam on the substrate.

  In the former method, it is necessary to drive the stage in the X direction and the Y direction, so that the footprint of the apparatus is large. In the latter method, there is a drawback that the irradiation position accuracy of the laser beam is worse than when the XY stage is used.

  With reference to FIG. 6, the problem of the laser processing performed using a galvano scanner is demonstrated.

  For example, when patterning is performed by irradiating a laser beam to the positions indicated by the target processing tracks 81 and 83 on the substrate, the actual processing track is the processing mark 82 due to the accuracy of the irradiation position of the laser beam by the galvano scanner. , 84 in some cases. In FIG. 6, when control is performed so that the laser beam is incident along the target machining locus 81, the machining locus obtained by actually entering the laser beam is the machining trace 82. A corresponding machining locus is a machining mark 84.

  As shown in the figure, the two processing marks 82 and 84 cross each other. It is not preferable that the processing marks have an intersection in the patterning process.

  A technique is known in which an alignment mark is formed on the surface of a workpiece and observed with a CCD camera, thereby improving the irradiation position accuracy of the laser beam (see, for example, Patent Document 1).

JP 2006-35227 A

  An object of the present invention is to provide a laser processing apparatus capable of performing high-quality processing.

  Another object of the present invention is to provide a laser processing method capable of performing high quality processing.

  According to one aspect of the present invention, a laser light source that emits a laser beam, a stage that holds a workpiece, and a laser beam that is emitted from the laser light source, the workpiece whose incident position is held on the stage. An optical system including a first optical deflector that scans so as to move, a second optical deflector, and a processing target held on the stage via the first and second optical deflectors An image sensor that images a partial area on the surface of an object and an area different from the position where the laser beam is incident on the surface of the object to be processed held on the stage are imaged by the image sensor. Thus, there is provided a laser processing apparatus having a control device for controlling the second optical deflector.

  According to another aspect of the present invention, a step of preparing a processing target in which a first target line and a second target line to be laser processed are defined, and a first on the processing target is provided. Controlling the laser irradiation optical system so that the laser beam scans on the target line to perform laser processing to form a first processing mark, and measuring a shift of the first processing mark with respect to the first target line Then, the second target line is corrected based on the measurement result, and laser processing is performed by controlling the laser irradiation optical system so that the laser beam scans on the corrected second target line. And a step of forming a laser processing method.

  ADVANTAGE OF THE INVENTION According to this invention, the laser processing apparatus which can perform a high quality process can be provided.

  In addition, a laser processing method capable of performing high-quality processing can be provided.

  1A and 1B show a panel 50 that is a workpiece to be processed by the laser processing apparatus and method according to the embodiment. The panel 50 is a panel processed in the manufacturing process of the solar cell.

  FIG. 1A is a schematic plan view showing a panel 50 in one step of manufacturing a solar cell. The panel 50 is, for example, a rectangular shape having a length of 1000 mm and a width of 1400 mm.

  FIG. 1B shows a schematic cross section of the panel 50. The panel 50 includes a transparent electrode film having a thickness of 0.1 to 0.2 μm, for example, an ITO (Indium Tin Oxide) film 52, an amorphous film having a thickness of 1 μm, on a glass substrate 51 having a thickness of 0.5 to 0.7 mm. A silicon film 53 and an Ag (silver) film 54 having a thickness of 0.1 μm are stacked in this order.

  In each step of manufacturing the solar cell, the panel 50 is irradiated with a laser beam to remove the ITO film 52, the amorphous silicon film 53, and the Ag film 54 at the irradiation position, and patterning is performed. In the drawing, the portions where the ITO film 52, the amorphous silicon film 53, and the Ag film 54 are removed are shown as removal portions 52a to 54a. In manufacturing a solar cell, after patterning of the ITO film 52 is completed, an amorphous silicon film 53 is formed on the ITO film 52, and after patterning of the amorphous silicon film 53 is completed, an Ag film 54 is formed thereon. .

  The laser processing method shown in the following embodiments is not only applied between the amorphous silicon film 53 and the Ag film 54, for example, but also between the ITO film 52 and the amorphous silicon film 53, or between the ITO film 52 and the Ag film. 54 can also be applied. Further, the present invention can be applied to patterning not only between the upper and lower films but also in the same film, for example, in the ITO film 52.

  FIG. 2 is a schematic diagram illustrating a laser processing apparatus according to an embodiment. The laser processing apparatus according to the embodiment includes a laser light source 21, a variable attenuator 22, an expander 23, a uniform optical system 24, a mask 25, movable imaging lenses 26 and 32, a dichroic mirror 27, a galvano scanner 28 and 31, an illumination light source 29, A stage 30, a CCD camera 33, and a control device 34 are included.

  The laser light source 21 receives a trigger signal sent from the control device 34 and emits a pulse laser beam 35. The laser light source 21 includes, for example, an Nd: YAG laser oscillator and a nonlinear optical crystal. The pulse laser beam 35 is, for example, a second harmonic of an Nd: YAG laser. The pulse width of the pulse laser beam 35 is, for example, 30 nsec.

  The pulse laser beam 35 includes, for example, a homogenizer via a variable attenuator 22 that attenuates the amount of incident laser beam with a variable attenuation factor, and an expander 23 that expands and emits the beam diameter of the incident laser beam. Is incident on a uniform optical system 24. The attenuation rate of the light amount of the pulse laser beam 35 by the variable attenuator 22 is controlled by a control signal transmitted from the control device 34.

  The uniform optical system 24 uniformizes the light intensity distribution in the beam cross section of the pulse laser beam 35 on the homogenization surface of the homogenizer. On the homogenized surface, a mask 25 having a light transmitting region and a light shielding region and shaping the cross-sectional shape of the pulse laser beam 35 is disposed.

  The pulse laser beam 35 whose cross-sectional shape is shaped by the mask 25 enters the movable imaging lens 26.

  A panel 50 is placed on the stage 30. The panel 50 is the panel 50 described with reference to FIGS. 1 (A) and 1 (B), for example. However, the Ag film 54 is not patterned.

  The movable imaging lens 26 forms an image of the pulse laser beam 35 on the mask 25 surface on the Ag film 54 of the panel 51.

  The pulse laser beam 35 emitted from the movable imaging lens 26 passes through the dichroic mirror 27. The pulse laser beam 35 transmitted through the dichroic mirror 27 enters the panel 50 through the galvano scanner 28. The galvano scanner 28 includes two oscillating mirrors (galvano mirrors), and emits the laser beam by changing the emission direction of the incident laser beam in a two-dimensional direction. The pulse laser beam 35 scans the Ag film 54 of the panel 50 by the galvano scanner 28, and the Ag film 54 at the incident position is removed to perform patterning. The movable imaging lens 26 has a pulse so that the pulse laser beam 35 on the surface of the mask 25 is always focused on the Ag film 54 of the panel 50 even if the incident position of the pulse laser beam 35 on the panel 50 changes. The laser beam 35 is displaced in a direction parallel to the optical axis direction (traveling direction).

  Scanning of the pulsed laser beam 35 by the galvano scanner 28 and displacement of the movable imaging lens 26 are controlled by the control device 34.

  An illumination light source 29 is installed above the stage 30. The panel 50 placed on the stage 30 is illuminated by the illumination light emitted from the illumination light source 29.

  Illumination light reflected at a predetermined position of the panel 50 travels along a path indicated by a one-dot chain line in the drawing, that is, through a galvano scanner 28, a dichroic mirror 27, a galvano scanner 31, and a movable imaging lens 32. The light enters the CCD camera 33.

  The movable imaging lens 32 forms an image at a predetermined position of the panel 50 on the light receiving surface of the CCD camera 33. Image information of the panel 50 obtained by the CCD camera 33 is transmitted to the control device 34.

  By operating the galvano scanners 28 and 31, it is possible to obtain image information of the entire area of the panel 50. Further, since the galvano scanner 31 is arranged in series with the galvano scanner 28, the image information of the panel 50 can be obtained simultaneously with the patterning of the Ag film 54. The operation of the galvano scanner 31 is controlled by the control device 34.

  The movable imaging lens 32 is arranged in the direction of the optical axis of the illumination light so that the illumination light reflected at the imaging position is always imaged on the light receiving surface of the CCD camera 33 even if the imaging position on the panel 50 changes. It is displaced in a direction parallel to (traveling direction). Control relating to the displacement of the movable imaging lens 32 is also performed by the controller 34.

  The control device 34 includes a storage device 34a. The storage device 34a stores, for example, target incident position information indicating a position on the panel 50 where the pulse laser beam 35 emitted from the laser light source 21 should be incident. As will be described in detail below, the control device 34 corrects the target incident position information stored in the storage device 34a based on the image information of the panel 50 captured by the CCD camera 33, and the corrected target incident position. The galvano scanner 28 is controlled so that the pulse laser beam 35 is incident on the position represented by the information.

  With reference to FIG. 3, the laser processing method performed using the laser processing apparatus by an Example is demonstrated.

  The target processing locus 81 is, for example, a straight line, and is defined by target incident position information stored in the storage device 34a prior to the processing in order to perform patterning processing of the amorphous silicon film 53 that is the lower layer of the Ag film 54. The target irradiation position of the laser beam. Further, the processing mark 85 is different from the target processing path 81 due to, for example, the irradiation position accuracy of the laser beam by the galvano scanner, although the irradiation optical system is controlled so that the laser beam scans the target processing path 81. This is a patterning locus formed by actually entering a laser beam on the amorphous silicon film 53 at a different position. Further, the target processing trajectory 83 is a target irradiation position of the laser beam defined prior to the processing for patterning the Ag film 54. When viewed from the vertical direction of the panel 50, for example, the target processing trajectory 83 A straight line parallel to the trajectory 81.

  For the convenience of the following description, the direction in which the straight lines of the target machining trajectories 81 and 83 extend (the downward direction in the drawing in FIG. 3) is the X axis direction, and the direction orthogonal to the X axis direction (the right direction in the drawing in FIG. 3). ) Is the Y-axis direction.

  FIG. 3 shows one state during patterning of the Ag film 54. The locus (patterning locus) of the removed portion 54a of the Ag film 54 that has been removed by the laser beam up to the illustrated time is the processing mark 86, and at the illustrated time, the laser beam is incident on the processing position 89, and the processing position 89 The Ag film 54 is removed. The patterning of the Ag film 54 is performed in the X-axis direction as a whole.

  In this state, the CCD camera 33 is photographing the imaging area 87. The imaging area 87 is demarcated centering on a point located in the X axis direction of 50 to 100 mm, for example, 50 mm, for example, from a point on the target machining locus 81 having the same X coordinate as the machining position 89, and the machining mark 85 having the same X coordinate as that point. This is a region including the upper point (observation point 88).

  Image information of the imaging area 87 imaged by the CCD camera 33 is transmitted to the control device 34, and in the Y-axis direction of the observation point 88 with reference to the Y coordinate of the observation point 88 and the target processing locus 81. The displacement ΔY is detected.

  In the patterning processing of the Ag film 54 shown in this figure, when the position where the observation point 88 and the X coordinate are equal is processed, the position displaced by ΔY in the Y-axis direction from the target processing locus 83 is changed to a new laser beam. Determined as the target irradiation position.

  As described above, in the laser processing method according to the embodiment, during laser processing (patterning processing), the position corresponding to the position existing in the traveling direction of the current processing among the adjacent processing marks 85 (patterning trajectory) in the lower layer is monitored. Then, the processing is performed while correcting the target irradiation position (target processing locus 83) of the laser beam defined before the processing.

  For example, when one of two oscillating mirrors (galvanomirrors) included in the galvano scanner 28 scans the laser beam in the X direction and the other one scans the laser beam in the Y direction, the laser A command value (a control signal transmitted from the control device 34) that has been given to the oscillating mirror (galvanometer mirror) that scans the beam in the Y direction is corrected.

  The description of the laser processing method according to the embodiment will be continued with reference to FIG.

  As described above, the laser processing method according to the embodiment detects a deviation amount from the reference position (target processing trajectory 81) of the processing mark 85 existing in the processing progress direction during processing, and a new laser is based on the detected amount. A target irradiation position of the beam is determined, and processing is performed by emitting a laser beam toward the position.

  In FIG. 4, a target processing locus 90 that is a target irradiation position of a new laser beam obtained by correcting the target processing locus 83 is indicated by a one-dot chain line. Since the target machining trajectories 81 and 83 are parallel to each other, the machining trace 85 and the target machining trajectory 90 are parallel to each other.

  In the patterning process of the Ag film 54, the operation of the galvano scanner 28 and the movable imaging lens 26 is controlled by the control device 34 so that the laser beam is imaged and incident on a point on the target processing locus 90.

  The machining mark 86 is a patterning locus that is patterned by a laser beam that is emitted toward a point on the target machining locus 90 and is actually incident on the Ag film 54.

  Since the target irradiation position of the laser beam is newly determined based on the processing mark 85 of the lower layer (amorphous silicon film 53), even if an error occurs in the laser beam irradiation position of the galvano scanner, the lower layer (amorphous silicon film 53) A processing mark 86 that does not intersect with the processing mark 85 can be formed (patterned) on the Ag film 54.

  Please refer to FIG. Next, when machining, for example, the deviation between the machining trace 86 and the target machining locus 83 is measured, the target machining locus 91 defined in parallel with the target machining locus 83 is corrected, and the target machining locus parallel to the machining trace 86 is obtained. 92 is obtained, and a new machining trace is formed by controlling the laser irradiation optical system so that the laser beam scans on the target machining locus 92.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these.

  For example, although the imaging optical system is used in the laser processing apparatus according to the embodiment, a condensing optical system may be adopted instead of the imaging optical system.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like are possible.

  It can be suitably used for laser processing in general, for example, patterning processing performed by irradiating a laser beam.

(A) And (B) shows the panel 50 which is a process target object processed with the laser processing apparatus and method by an Example. It is the schematic which shows the laser processing apparatus by an Example. It is a figure for demonstrating the laser processing method by an Example. It is a figure for demonstrating the laser processing method by an Example. It is a figure for demonstrating the laser processing method by an Example. It is a figure for demonstrating the problem of the laser processing performed using a galvano scanner.

Explanation of symbols

21 laser light source 22 variable attenuator 23 expander 24 uniform optical system 25 mask 26 movable imaging lens 27 dichroic mirror 28 galvano scanner 29 illumination light source 30 stage 31 galvano scanner 32 movable imaging lens 33 CCD camera 34 control device 34a storage device 35 pulse Laser beam 50 Panel 51 Glass substrate 52 ITO film 53 Amorphous silicon film 54 Ag films 52 a to 54 a Removal portions 81, 83 Target processing trajectories 82, 84 Processing marks 85, 86 Processing marks 87 Imaging area 88 Observation points 89 Processing positions 90, 91 , 92 Target machining locus

Claims (7)

A laser light source for emitting a laser beam;
A stage for holding the workpiece,
An optical system including a first optical deflector that scans the laser beam emitted from the laser light source so that the incident position moves on the workpiece held by the stage;
A second optical deflector;
An image sensor for imaging a partial area on the surface of the workpiece held on the stage via the first and second optical deflectors;
A control device for controlling the second optical deflector so that an area different from the position where the laser beam is incident is picked up by the image sensor on the surface of the workpiece held by the stage; A laser processing apparatus.   The control device includes a storage device that stores target incident position information indicating a position where a laser beam emitted from the laser light source is to be incident, and image information of the surface of the processing object imaged by the imaging element 2. The laser according to claim 1, wherein the first deflector is controlled such that the target incident position information is corrected based on the laser beam and the laser beam is incident on a position represented by the corrected target incident position information. Processing equipment.   The laser processing apparatus according to claim 2, wherein the control device corrects the target incident position information based on a position of a processing mark on a surface of the processing target imaged by the imaging element. Preparing a workpiece in which a first target line and a second target line to be laser processed are defined;
A step of controlling the laser irradiation optical system to perform laser processing so as to scan a laser beam on a first target line on the processing object to form a first processing mark;
The shift of the first processing mark with respect to the first target line is measured, the second target line is corrected based on the measurement result, and the laser beam is scanned on the corrected second target line. A laser processing method comprising: controlling a laser irradiation optical system to perform laser processing to form a second processing mark. When an XY orthogonal coordinate system is defined on the surface of the workpiece,
The first target line and the second target line are parallel to the X direction;
Forming the second processing mark,
The first machining trace at the position of the second X coordinate ahead of the first X coordinate where the laser beam is incident at the present time is observed, and the Y coordinate of the first machining trace is calculated. Process,
Measuring the amount of deviation in the Y-axis direction from the first target line to the second machining mark at the position of the second X coordinate;
Correcting the Y coordinate of the second target line at the position of the second X coordinate based on the measured deviation amount;
When the laser beam is incident on the second X coordinate position, the laser irradiation is performed so that the laser beam is incident on the corrected Y coordinate position of the second target line at the second X coordinate position. The laser processing method of Claim 4 including the process of controlling an optical system. A third target line to be further laser processed is defined on the workpiece,
After forming the second processing mark,
The deviation of the second processing mark with respect to the second target line is measured, the third target line is corrected based on the measurement result, and the laser beam is scanned on the corrected third target line. The laser processing method according to claim 4, further comprising a step of performing laser processing by controlling the laser irradiation optical system to form a third processing mark. A third target line to be further laser processed is defined on the workpiece,
After forming the second processing mark,
The shift of the first processing mark with respect to the first target line is measured, the third target line is corrected based on the measurement result, and the laser beam is scanned on the corrected third target line. The laser processing method according to claim 4, further comprising a step of performing laser processing by controlling the laser irradiation optical system to form a third processing mark.