JP6240497B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus that performs processing by irradiating a laser beam along a planned processing line on a substrate.

  As an apparatus for processing a substrate with a laser beam, for example, an apparatus disclosed in Patent Document 1 is known. In this type of processing apparatus, a green laser having a wavelength of about 532 nm is irradiated onto a workpiece such as a glass substrate. The green laser is generally transmitted through the glass substrate, but when the laser beam is focused and the intensity exceeds a certain threshold value, the glass substrate absorbs the laser beam. In such a state, plasma is generated in the condensing part of the laser beam, and thereby the glass substrate is evaporated. Processing such as forming a hole in the glass substrate can be performed using the principle described above.

  Patent Document 2 discloses an apparatus for forming a groove in a substrate by irradiating a workpiece with a laser beam a plurality of times. In the apparatus of Patent Document 2, the wavelength of plasma generated during processing is detected so that a groove can be formed reliably even if the thickness of the substrate varies. The irradiation of the laser beam is controlled by the detected plasma wavelength.

JP 2007-118054 A JP 2013-173160 A

  As shown in the apparatus of Patent Document 2, when the substrate is divided into a plurality of chips, it is necessary to irradiate the laser beam a plurality of times along the groove forming line. For this reason, it takes processing time to divide, and in order to shorten the processing time, it is desired to reduce the number of times of laser beam irradiation.

  An object of the present invention is to reduce a processing time when forming a groove by irradiating a laser beam or dividing a workpiece such as a substrate.

  A laser processing apparatus according to one aspect of the present invention is an apparatus that performs processing by irradiating a laser beam along a planned processing line on a workpiece. This apparatus has a work table on which a work to be processed is placed, a laser beam output unit for outputting a laser beam, and a laser beam from the laser beam output unit is branched into a plurality of laser beams and condensed on the work. And a scanning mechanism for scanning a plurality of laser beams from the branching / condensing mechanism along a planned processing line.

  In this apparatus, the laser beam output from the laser beam output unit is branched into a plurality of laser beams. Then, the plurality of branched laser beams are scanned along the planned processing line. For this reason, compared with the case where it processes with one laser beam like the conventional apparatus, processing time is shortened.

  In the laser processing apparatus according to another aspect of the present invention, the branching / condensing mechanism includes a quarter-wave plate, a Wollaston prism, and condensing means. The quarter-wave plate receives the laser beam from the laser beam output unit and outputs circularly polarized light. The Wollaston prism splits the circularly polarized light output from the quarter wavelength plate into two laser beams. The condensing means condenses the two laser beams output from the Wollaston prism on the workpiece.

  Here, it is conceivable to use a DOE as a diffractive optical element as a configuration for branching one laser beam into a plurality of parts. A plurality of laser spots can be easily formed by branching the laser beam using DOE.

  However, when DOE is used, higher-order diffracted light and 0th-order light than the ± 1st-order diffracted light that contributes to processing are irradiated outside the processing line. There is a problem that the workpiece is damaged by the irradiation of the high-order diffracted light and zero-order light.

  Therefore, in the apparatus of the present invention, a quarter-wave plate for converting linearly polarized light into circularly polarized light is provided in front of the Wollaston prism, and one laser beam is branched into two laser beams by the Wollaston prism. Yes.

  With this apparatus, it is possible to easily obtain two branched laser beams. Further, in this apparatus, there is no generation of high-order diffracted light and zero-order light as generated by DOE, and damage to the workpiece can be suppressed.

  In the laser processing apparatus according to still another aspect of the present invention, the branching / condensing mechanism further includes a rotation mechanism that rotates the Wollaston prism.

  By rotating the Wollaston prism, the laser beam can be easily scanned along a curved processing line.

  In the laser processing apparatus according to still another aspect of the present invention, the processing scheduled line includes a straight portion and a curved portion. The rotation mechanism rotates the Wollaston prism on the curved portion according to the curvature of the curved portion. In addition, when the two laser beams are scanned along the curved portion, the scanning mechanism scans so that the incident light center of the Wollaston prism coincides with the center of the string connecting the condensing points of the two laser beams. To do.

  Here, the two laser spots can be scanned along an arbitrary curve by adjusting the rotation angle of the Wollaston prism.

  In the laser processing apparatus according to still another aspect of the present invention, the branching / condensing mechanism further includes an interval adjusting mechanism for changing the interval between the two branched laser beams.

  When the interval between the two branched laser beams is adjusted, the interval between the irradiation times of the two laser beams (the time between the irradiation timing of the previous laser beam and the irradiation timing of the subsequent laser beam: Can be changed). For this reason, the depth of the processed groove can be changed, or in the case of drilling, the hole diameter can be changed. Further, when the planned machining line includes a straight line portion and a curved line portion, it becomes easy to cope with the case where it is necessary to change the processing interval time between the straight line portion and the curved line portion.

  In the laser processing apparatus according to still another aspect of the present invention, the processing scheduled line includes a straight portion and a curved portion. The interval adjusting mechanism makes the interval between the two laser beams narrower than the interval on the linear portion on the curved portion.

  When the planned processing line includes a straight portion and a curved portion, the length of the planned processing line between the two laser beams is longer in the curved portion. Therefore, by making the interval between the two laser beams narrower than that on the straight line portion on the curved portion, the processing interval time in the straight portion and the curved portion can be made the same.

  In the laser processing apparatus according to still another aspect of the present invention, the interval adjusting mechanism has a beam expander disposed between the Wollaston prism and the light condensing means.

  Here, the interval adjusting mechanism can be realized with a simple configuration.

  In the laser processing apparatus according to still another aspect of the present invention, the branching / condensing mechanism further includes a wave plate rotating mechanism for rotating the quarter wave plate.

  By rotating the quarter wavelength plate, the energy ratio at the condensing point of the two laser beams can be adjusted.

  In the present invention as described above, in the laser processing apparatus, it is possible to shorten the processing time when forming a groove or dividing a workpiece by irradiating a laser beam.

1 is an external perspective view of a laser processing apparatus according to an embodiment of the present invention. The expansion perspective view of a work table. The perspective view which expands and shows the structure of a laser beam irradiation head. The schematic diagram which shows a quarter wavelength plate and a Wollaston prism. The figure which shows the structure of a Wollaston prism. The schematic diagram explaining the operation | movement which scans a curve part. The schematic diagram explaining the operation | movement which scans a linear part and a curve part.

[overall structure]
FIG. 1 shows the overall configuration of a laser processing apparatus according to an embodiment of the present invention. This laser processing apparatus is an apparatus for irradiating a laser beam, for example, on a glass substrate as a workpiece to perform processing such as drilling. This apparatus includes a bed 1, a work table 2 on which a glass substrate as a workpiece is placed, and a laser beam irradiation head 3 for irradiating the glass substrate with a laser beam. Here, as shown in FIG. 1, in the plane along the upper surface of the bed 1, the axes orthogonal to each other are defined as the X axis and the Y axis, and the vertical axis orthogonal to these axes is defined as the Z axis. Further, both directions (+ direction and − direction) along the X axis are defined as the X axis direction, both directions along the Y axis are defined as the Y axis direction, and both directions along the Z axis are defined as the Z axis direction.

[Work table and its moving mechanism]
<Worktable 2>
The work table 2 is formed in a rectangular shape, and a table moving mechanism 5 for moving the work table 2 in the X-axis direction and the Y-axis direction is provided below the work table 2.

  The work table 2 has a plurality of blocks 6 as shown in an enlarged view in FIG. The plurality of blocks 6 are members for lifting and supporting the glass substrate G indicated by a two-dot chain line in the drawing from the surface of the work table 2, and avoid processing planned lines L (shown by broken lines) of the glass substrate G. Therefore, it can be attached to an arbitrary position of the work table 2. The work table 2 is formed with a plurality of air inlets 2a in a lattice shape, and each block 6 is formed with an air inlet hole 6a penetrating in the vertical direction. Then, by connecting the intake hole 6a of the block 6 and the intake port 2a of the work table 2, the glass substrate G disposed on the block 6 can be adsorbed and fixed. The intake mechanism is constituted by a well-known exhaust pump or the like and will not be described in detail.

<Table moving mechanism 5>
As shown in FIG. 1, the table moving mechanism 5 has a pair of first and second guide rails 8 and 9, and first and second moving tables 10 and 11, respectively. The pair of first guide rails 8 is provided on the upper surface of the bed 1 so as to extend in the Y-axis direction. The first moving table 10 is provided on the upper part of the first guide rail 8, and has a plurality of guide portions 10 a that are movably engaged with the first guide rail 8 on the lower surface. The second guide rail 9 is provided on the upper surface of the first moving table 10 so as to extend in the X-axis direction. The second moving table 11 is provided on the upper part of the second guide rail 9 and has a plurality of guide portions 11 a that are movably engaged with the second guide rail 9 on the lower surface. The work table 2 is attached to the upper part of the second moving table 11 via a fixing member 12.

  By the table moving mechanism 5 as described above, the work table 2 is movable in the X-axis direction and the Y-axis direction. The first and second moving tables 10 and 11 are driven by a driving means such as a well-known motor, although details are omitted.

[Laser beam irradiation head 3]
As shown in FIGS. 1 and 3, the laser beam irradiation head 3 is mounted on a portal frame 1a disposed on the upper surface of the bed 1, and includes a laser beam output unit 15, an optical system 16, and a wallace inside. A hollow motor 17 in which a ton prism (described later) is incorporated, a beam expander 18 for adjusting the interval, and an fθ lens 20 as a condenser lens. The optical system 16, the hollow motor 17 having a Wollaston prism, the beam expander 18, and the fθ lens 20 are used to branch the laser beam from the laser beam output unit 15 into a plurality of laser beams and condense them on the substrate. A light collecting mechanism is configured.

  Further, an X-axis direction moving mechanism 21 for moving the laser beam irradiation head 3 in the X-axis direction and a Z-axis direction moving mechanism 22 for moving the hollow motor 17 and the fθ lens 20 in the Z-axis direction are provided. It has been.

<Laser beam output unit 15>
The laser beam output unit 15 is composed of a laser tube similar to the conventional one. The laser beam output unit 15 emits a green laser beam having a wavelength of 532 nm to the side opposite to the work table 2 along the Y axis.

<Optical system 16>
The optical system 16 guides the laser beam from the laser beam output unit 15 into the hollow motor 17. As shown in an enlarged view in FIG. 3, the optical system 16 includes first to fourth mirrors 25 to 28, a power monitor 29 that measures a laser output, a beam expander 30, and a ¼ wavelength plate 31. ,have.

  The first mirror 25 is disposed in the vicinity of the output side of the laser beam output unit 15 and reflects the laser beam emitted in the Y-axis direction in the X-axis direction. The second mirror 26 is arranged side by side with the first mirror 25 in the X-axis direction, reflects the laser beam traveling in the X-axis direction in the Y-axis direction, and guides it to the work table 2 side. The third mirror 27 is disposed on the opposite side of the second mirror 26 in the Y-axis direction, and reflects the laser beam reflected by the second mirror 26 and guides it in the X-axis direction. The fourth mirror 28 is disposed above the hollow motor 17, reflects the laser beam reflected by the third mirror 27, and guides it to the hollow motor 17 through the quarter-wave plate 31.

  The beam expander 30 is disposed between the second mirror 26 and the third mirror 27, and is provided to spread the laser beam reflected by the second mirror 26 into a parallel light beam having a constant magnification. This beam expander 30 makes it possible to focus the laser beam on a smaller spot.

  As schematically shown in FIG. 4, the quarter-wave plate 31 is disposed in the front stage of the hollow motor 17 (upstream side in the laser beam traveling direction). The quarter wavelength plate 31 is provided to convert linearly polarized light into circularly polarized light. Further, a motor 19 for rotating the quarter wavelength plate 31 is provided.

<Hollow motor 17>
As shown in the schematic diagram of FIG. 4, the hollow motor 17 has a rotation axis (also a center of incident light) extending in the Z-axis direction at the center, and a central portion including the rotation axis is hollow. A Wollaston prism 33 is disposed in the hollow portion.

  As shown in FIG. 5, the Wollaston prism 33 includes two crystal prisms 33a and 33b. The two quartz prisms 33a and 33b have optical axes orthogonal to each other. The Wollaston prism 33 has a function of branching an incident laser beam into two linearly polarized beams (abnormal light and ordinary light) orthogonal to each other. In FIG. 5, a straight line on the optical axis and a black circle indicate the vibration direction of the polarized light.

  Here, the Wollaston prism 33 cannot be branched into two beams unless it is arranged at a predetermined angle with respect to the incident laser beam. That is, when the Wollaston prism 33 is rotated, the incident laser beam is branched into two beams at a certain angular position, but cannot be branched at other angular positions.

  Therefore, a quarter wavelength plate 31 for converting linearly polarized light into circularly polarized light is provided in front of the Wollaston prism 33. As a result, the laser beam incident on the rotating hollow motor 17 becomes circularly polarized light.

  With the configuration described above, even if the Wollaston prism 33 is rotated, the laser beam can be branched into two laser beams at any angular position.

  The energy ratio of the two laser beams branched by the Wollaston prism 33 can be changed by rotating the quarter wavelength plate 31 by the motor 19.

<Beam expander 18>
The beam expander 18 is disposed between the Wollaston prism 33 and the fθ lens 20. For example, by providing a beam expander 18 having a magnification (1 / M), when a laser beam having a diameter D enters the beam expander 18, a laser beam having a diameter D / M is emitted from the beam expander 18. The two laser beams incident on the beam expander 18 at the branch angle 2θ are emitted at the branch angle 2Mθ. When the focal length of the fθ lens 20 is f, the interval between the two laser beams on the substrate is 2 × f × M × θ. Thus, the interval between the two laser beams can be adjusted by the magnification (1 / M) of the beam expander 18.

<Fθ lens>
The fθ lens 20 is a lens for condensing the two laser beams emitted from the beam expander 18 at an arbitrary position in the Z-axis direction on the glass substrate G or in the glass substrate G.

<Support and transport system of laser beam irradiation head>
The laser beam irradiation head 3 as described above is supported by the portal frame 1a of the bed 1 as described above. More specifically, as shown in FIG. 3, a pair of third guide rails 36 extending in the X-axis direction are provided on the upper surface of the portal frame 1a. The drive mechanism that does not constitute the X-axis direction moving mechanism 21. A support member 37 is movably supported by the pair of third guide rails 36. The support member 37 includes a horizontal support member 38 supported by the third guide rail 36 and a vertical support member 39 extending downward from one end of the horizontal support member 38 on the work table 2 side. A pair of fourth guide rails 40 extending in the Z-axis direction are provided on the side surface of the vertical support member 39, and the pair of fourth guide rails 40 and a driving mechanism (not shown) drive the Z-axis direction moving mechanism 22. It is composed. A third moving table 41 is supported on the fourth guide rail 40 so as to be movable in the Z-axis direction.

  The laser output unit 15, the first to fourth mirrors 25 to 28, the power monitor 29, and the beam expander 30 are supported by the lateral support member 38. Further, the quarter wave plate 31, the hollow motor 17 including the Wollaston prism 33, the gap adjusting beam expander 18, and the fθ lens 20 are supported by the third moving table 41.

[Operation]
When processing a glass substrate, first, a plurality of blocks 6 are installed on the surface of the work table 2. At this time, the plurality of blocks 6 are arranged so as to avoid the processing line L of the glass substrate G, as shown in FIG. The glass substrate G to be processed is placed on the plurality of blocks 6 installed as described above.

  Next, the laser beam irradiation head 3 is moved in the X-axis direction by the X-axis direction moving mechanism 21, and the work table 2 is moved in the Y-axis direction by the table moving mechanism 5. The light spot is positioned at the start position of the processing line L.

  After the laser beam irradiation head 3 and the glass substrate G are moved to the processing position as described above, the processing is performed by irradiating the glass substrate G with the laser beam. Here, the laser beam emitted from the laser beam output unit 15 is reflected by the first mirror 25 and guided to the second mirror 26. The laser output of the laser beam incident on the first mirror 25 is measured by the power monitor 29. The laser beam incident on the second mirror 26 is reflected in the Y-axis direction, and the light beam is expanded by the beam expander 30 and guided to the third mirror 27. The laser beam reflected by the third mirror 27 is further reflected by the fourth mirror 28 and input to the quarter wavelength plate 31. The quarter wavelength plate 31 outputs a laser beam converted into circularly polarized light.

  The laser beam converted into the circularly polarized light is input to a Wollaston prism 33 provided inside the hollow motor 17. The laser beam that has passed through the Wollaston prism 33 is branched into two laser beams at a branching angle 2θ and output. As described above, the two laser beams pass through the beam expander 18 having a magnification (1 / M) and are output at a branching angle 2Mθ. Then, two laser beams with an interval of 2 × f × M × θ are irradiated on the substrate by the fθ lens 20 having a focal length f.

  Laser processing can be performed in a shorter time by scanning the two laser beams obtained as described above along the planned processing line.

[Curved part processing]
As shown in FIG. 6, when two laser beams are scanned along a curve of radius R, it is necessary to scan so that the center of the incident light is located inside the curve (indicated by a broken line). More specifically, as shown in FIG. 7A, first, when moving from the straight line portion to the curved portion, the radius r (the interval between the two laser beams is centered on the position P2 of one laser beam. ) And the rotation angle of the Wollaston prism 33 are determined so that the position P1 of the other laser beam is at the intersection of the circle of the curved line of the processing planned line.

  In the curved portion, as shown in FIG. 7B, the incident light center is set to be the center of the string connecting the two laser beams. Thereby, it is possible to scan the two laser beams along the planned processing line without error.

[Feature]
(1) Since one laser beam is branched into two laser beams and each is scanned along the same scheduled processing line, the processing time can be shortened. Further, even when the planned processing line includes a curved portion, the processing can be performed easily and without error.

  (2) Since the laser beam is branched by the Wollaston prism 33, there is no generation of high-order diffracted light and zero-order light as in the case of using DOE. Therefore, damage to the substrate can be suppressed.

  (3) By changing the magnification of the beam expander 18, the interval between the two laser beams can be changed. For this reason, for example, the hole diameter can be changed in the drilling process.

  (4) By adjusting the quarter wavelength plate 31, the energy ratio at the condensing point of the two laser beams can be adjusted.

[Other Embodiments]
The present invention is not limited to the above-described embodiments, and various changes or modifications can be made without departing from the scope of the present invention.

  (A) When the processing planned line includes a straight line portion and a curved portion, the length of the processing planned line between the two laser beams is longer in the curved portion. Accordingly, when scanning is performed while keeping the interval between the two laser beams the same between the straight line portion and the curved portion, the processing interval from the timing processed with one laser beam to the timing processed with the other laser beam is detected in the curved portion. The time will be longer. In order to make the processing interval time the same between the linear portion and the curved portion, the interval between the two laser beams may be narrowed at the curved portion.

  In order to realize this, the beam expander provided between the Wollaston prism 33 and the fθ lens 20 may be a zoom expander. By using the zoom beam expander, not only can the processing interval time be the same for the straight line part and the curved part, but in the drilling process, the hole diameter can be controlled during processing, and a tapered hole is processed. be able to.

  (B) When the beam diameter is multiplied by (1 / M) by the beam expander 18, the condensed beam diameter by the fθ lens 20 is M times on the substrate (image plane).

  If it is necessary to prevent this, the magnification of the beam expander 30 on the laser light source side from the Wollaston prism 33 may be set to M times.

  (C) The beam expander 18 on the emission side of the Wollaston prism 33 and the fθ lens 20 may be configured as an integral zoom lens.

  (D) Although the fθ lens is used as the condensing unit, the condensing unit may be any lens that can condense the laser beam, and is not limited to the fθ lens.

  (E) In the above embodiment, an apparatus for processing a glass substrate using a green laser has been described. However, even if a workpiece of another material is processed using a laser light source of another wavelength in the laser beam output unit. For example, the sapphire substrate may be processed using a UV laser.

2 Work table 3 Laser beam irradiation head 5 Table moving mechanism 15 Laser beam output unit 16 Optical system 17 Hollow motor 18 Beam expander 19 Motor 20 fθ lens 31 1/4 wavelength plate 33 Wollaston prism

Claims (5)

A laser processing apparatus for performing processing by irradiating a laser beam along a processing scheduled line including a linear portion and a curved portion of a workpiece,
A work table on which a work to be machined is placed;
A laser beam output section for outputting a laser beam;
A branching / condensing mechanism for branching the laser beam from the laser beam output unit into a plurality of laser beams and condensing on the workpiece;
A scanning mechanism that scans a plurality of laser beams from the branching / condensing mechanism along the planned processing line;
Equipped with a,
The branching / condensing mechanism is
A quarter-wave plate that receives the laser beam from the laser beam output unit and outputs circularly polarized light;
A Wollaston prism that splits the circularly polarized light output from the quarter-wave plate into two laser beams;
Condensing means for condensing the two laser beams output from the Wollaston prism on the workpiece;
A rotation mechanism for rotating the Wollaston prism;
Have
The rotating mechanism rotates the Wollaston prism according to the curvature of the curved portion on the curved portion,
In the scanning mechanism, when two laser beams are scanned along the curved portion, the incident light center of the Wollaston prism coincides with the center of the string connecting the condensing points of the two laser beams. Scan,
Laser processing equipment. The laser processing apparatus according to claim 1 , wherein the branching / condensing mechanism further includes an interval adjusting mechanism for changing an interval between the two branched laser beams. Before Symbol interval adjustment mechanism, it said over curved portion narrower than an interval of the interval of the laser beam of the two on the straight line portion,
The laser processing apparatus according to claim 2 . 4. The laser processing apparatus according to claim 2 , wherein the interval adjusting mechanism includes a beam expander disposed between the Wollaston prism and the condensing unit. 4. The laser processing apparatus according to claim 1, wherein the branching / condensing mechanism further includes a wave plate rotating mechanism for rotating the quarter wave plate. 5.

Images