JP2004268144A - Laser beam machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining device of a simultaneous multibeam machining type by which the pitch spacing in linear working can be adjusted easily and correctly with the diameter of a condensing beam kept constant. <P>SOLUTION: In the laser beam machining device which divides a single laser beam 12 into a plurality of laser beams 12a using a diffractive optical element or a combination of a diffractive optical element 3 and a condensing lens 5, collects lights, moves laser beams and a workpiece 17 relatively and performs a plurality of the linear working simultaneously with a plurality of laser beams, it is so composed that the diffractive optical element is rotated around an optical axis and the pitch spacing of a working line is adjusted by controlling the rotation angle. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a laser processing apparatus that simultaneously performs a plurality of line-shaped processes using a plurality of laser beams.

  Conventionally, as a device for performing line processing by a laser beam, a ceramic scriber for applying a scribe line to a chip resistor ceramic substrate to divide into individual chips, an ITO film or an amorphous silicon film for electrode formation of a thin film solar cell There are a patterning apparatus for performing a scribe line processing, a laser annealer for applying laser heat to a silicon thin film in a line shape in order to modify amorphous silicon by irradiating laser light to amorphous silicon. In this type of apparatus, a single laser beam is generally used for processing. On the other hand, in order to improve the throughput, it is conceivable to divide a single laser beam into a plurality of laser beams and perform line processing with the plurality of beams.

In order to divide the laser beam into a plurality of beams, there is a method of condensing each beam after dividing the incident laser beam into a constant intensity ratio using a semi-transparent mirror. This method requires complicated adjustment of the branching intensity ratio and the distance between the spots of the branching beam, and at the same time uses a large number of semi-transparent mirrors and condenser lenses for branching as the number of branching of the beam increases. Therefore, the optical system becomes extremely complicated and expensive.
Apart from this, there is a method of using a diffractive optical element (hereinafter abbreviated as DOE) for dividing a laser beam. A processing apparatus using this DOE (diffractive optical element) is described in, for example, Patent Document 1 and the like.
JP 2001-062578 A

  A DOE is an optical element in which a repetitive pattern of fine irregularities is formed on the surface of a substrate of an optical material such as quartz glass by using an etching (etching) technique. Can be divided into a desired beam arrangement and intensity ratio. By condensing the entire beam bundle diffracted by the DOE with a condensing lens, or by simultaneously providing the DOE itself with a condensing function, for example, a plurality of light beams having a uniform intensity ratio and arranged in a horizontal row at equal intervals. A laser focused beam can be obtained, and laser processing using a multi-beam can be simultaneously performed using the laser focused beam.

  In the line processing by the multi-beam, there is often a case where it is desired to freely change the pitch between lines, that is, the beam interval. An example is a ceramic scriber that processes chip resistor substrates of different chip sizes.

In Patent Document 1, it is shown that when a beam is divided and condensed in a horizontal row using a DOE and a condensing lens, the interval D of the condensed beam spot is expressed by the following equation (1). In the equation, λ is the wavelength of the laser beam, F is the focal length of the condenser lens, and Λ is the pitch of the etching pattern.
D = λ · F / Λ (1)

  In Patent Document 1, fine adjustment of the diameter and beam interval of a beam divided and collected by a combination of a DOE and a condenser lens is possible to some extent by adjusting the divergence angle of the incident laser beam and adjusting the interval between the DOE and the condenser lens. It is stated that. However, it is generally considerably difficult to freely change only the beam interval while keeping the beam diameter, which is an important parameter in laser processing, constant as can be seen from the equation (1). That is, changing the beam interval D changes at least one of λ, F, and Λ. However, since λ is difficult to change, F or Λ is changed, and F is changed. If the beam diameter changes and Λ is changed, several DOEs are prepared and exchanged. The method in which the beam diameter is changed is not applicable particularly when a large change in the beam interval is required.

Accordingly, when the focused beam interval D of the laser light having the wavelength λ divided into one horizontal row is significantly changed, for example, in a multi-beam simultaneous machining type ceramic scriber using DOE, the size of the chip resistor is, for example, 1005 In the case of changing from (length 1 mm, width 0.5 mm) to 0603 (length 0.6 mm, width 0.3 mm), a condensing lens or DOE that matches the processing pitch every time the size changes. There is a problem that needs to be replaced.
An object of the present invention is to provide a multi-beam simultaneous processing type laser processing apparatus capable of easily and accurately adjusting the pitch interval of line processing while keeping the diameter of the focused beam constant.

  The means of the present invention uses a diffractive optical element or a combination of a diffractive optical element and a condensing lens to divide and condense a single laser beam into a plurality of laser beams, and relatively move the laser beam and the workpiece. Then, in a laser processing apparatus that simultaneously processes a plurality of lines by a plurality of laser beams, the diffractive optical element is rotated around the optical axis, and the pitch interval of the processing lines is adjusted by adjusting the rotation angle. It is characterized by comprising.

When the DOE that divides the incident laser beam having the predetermined wavelength λ into, for example, a horizontal row is used, the divided beam interval at the focal point is expressed by the above formula (1), and laser processing is performed with such a divided beam. Referring to FIG. 2, if the angle formed by the straight line formed by the row 22 of the divided beam spots 13 with the interval D and the relative movement direction (Y-axis direction in the figure) of the beam and the workpiece is θ, The interval d between the lines 19 is expressed by the following equation (2).
d = D · sin θ …… (2)
From equation (2), θ can be changed by adjusting the direction of the split beam array with respect to the relative movement direction of the beam spot and the workpiece, that is, by adjusting the rotation angle about the optical axis of the DOE. The interval d can be arbitrarily adjusted within the range from the maximum value D to the minimum value 0.

  Between the diffractive optical element or a combination of the diffractive optical element and a condensing lens, and a laser processing point on the workpiece, there are a plurality of apertures through which a plurality of divided laser beams pass, It is preferable to provide a mask plate that rotates about the central axis in the same rotation direction by the same rotation angle with respect to the rotation of the diffractive optical element.

  DOE generally generates a weak noise component at an intermediate position between the divided beams. For example, unscheduled processing due to a noise component occurs on a processing target having a very low threshold for laser processing. In this configuration, this noise component is spatially blocked by the mask plate. Since this mask plate rotates around the central axis by the same rotation angle in the same rotation direction with respect to the rotation of the diffractive optical element, that is, with respect to the rotation of the DOE, the position of the aperture corresponding to each divided beam always coincides. Let This always prevents the noise component from reaching the workpiece.

  It is preferable that each aperture of the mask plate is provided with a mechanical or optical shutter. In this configuration, on / off of the beam passing through each aperture can be controlled independently by the shutter.

  It is preferable that an optical attenuator for adjusting the transmission power of each divided beam is detachably provided in each aperture of the mask plate. In this configuration, an optical attenuator including, for example, a dielectric multilayer mirror can be used to arbitrarily and independently control the laser power passing through each aperture.

In the present invention, the interval between the processing lines by the divided beams can be arbitrarily adjusted from a predetermined width to 0 by adjusting the rotation angle around the optical axis of the DOE, so that the diameter of the focused beam is constant. The machining pitch interval can be adjusted easily and accurately while maintaining the same, and there is an effect that it is possible to provide a multi-beam simultaneous machining type laser machining apparatus capable of handling a variety of workpieces.
In addition, the configuration in which the rotating mask plate having the aperture is provided has an effect of preventing unscheduled processing due to the noise component.
In addition, in the configuration in which each aperture of the mask plate is provided with a mechanical or optical shutter, it is possible to select and use any of a plurality of beams by controlling the shutter. In parallel line processing, for example, By selecting and using every other split beam, the pitch of the machining line can be easily and accurately changed to a predetermined pitch and twice that pitch.
In addition, in the configuration in which an optical attenuator is detachably attached to each aperture of the mask plate, the laser power passing through each aperture can be controlled arbitrarily and independently, so the processing depth in scribe processing, the processing width in thin film processing, etc. There is an effect that can be arbitrarily controlled for each processing line.

  Ceramic scriber for brine processing to divide the chip resistance ceramic substrate into individual chips.

  A first embodiment of the present invention will be described with reference to FIGS. The laser processing apparatus 1 includes a laser oscillator 2, a DOE 3, a DOE rotating device 4, a condenser lens 5, a stage 6, and the like.

The laser oscillation unit 2 includes a YAG laser oscillator 10 and a beam expander 11 provided subsequent to the YAG laser oscillator 10, and emits a laser beam 12.
The DOE 3 is configured to emit a single incident laser beam 12 from the laser oscillation unit 2 by dividing it into, for example, four beam rows 12a at equal intervals along the same straight line.
The DOE rotating device 4 supports the DOE 3 so as to be rotatable around its optical axis, and can rotate the DOE 3 accurately at a desired angle and adjust a minute angle, for example, rotation using a pulse motor or the like. A drive device is provided.

  The condensing lens 5 condenses each of the four beams divided into four pieces at a predetermined interval on a predetermined plane, that is, on the upper surface of a workpiece placed on the stage 6 described below. The beam spots 13 are formed in a line along a straight line. In the figure, reference numeral 14 denotes a dichroic mirror which is provided between the DOE 3 and the condenser lens 5 so as to bend the laser beam downward. Through the dichroic mirror 14, the position of the four beam spots 13 on the upper surface of the workpiece can be observed by the CCD camera 15 for observation. Reference numeral 24 denotes a reflecting mirror.

  The stage 6 has a horizontal upper surface 16, and a workpiece, for example, a ceramic substrate 17 is horizontally supported on the upper surface 16, and a stage driving unit 18 is provided so that the stage 6 can be moved horizontally to a desired position. The stage drive unit 18 includes an X-axis direction drive unit and a Y-axis direction drive unit so that an arbitrary fixed point of the ceramic substrate 17 can be moved to a desired position on the XY coordinates corresponding to the horizontal upper surface 16. It is the structure which has. In addition, a rotation adjustment unit that can adjust the rotation position around a predetermined Z axis perpendicular to the XY plane is provided. That is, the workpiece on the stage 6 can move in the X-axis direction and the Y-axis direction, and can be rotated and adjusted around the Z-axis.

In the laser processing apparatus 1, for example, when processing is performed in which the distance between the four beam spots 13 is D and the distance between the laser processing lines 19 is d, the following procedure is performed. Note that the workpiece is a ceramic substrate 17, and the scribe line 20 is laser processed on the ceramic substrate 17.
First, a ceramic substrate 17 that is a workpiece is placed on the stage 6, and the direction of the planned processing line 21 on the ceramic substrate 17 is made to coincide with the Y-axis direction by the stage driving unit 18. 13 is made to correspond to the start end portion of the corresponding scheduled machining line 21. At this time, if the beam spot row 22 coincides with the Y-axis direction, the DOE rotating device 4 rotates the DOE 3 by an angle θ, or the beam spot row 22 coincides with the X-axis direction. Then, the DOE rotating device 4 rotates the DOE 3 (90 ° −θ) so that the Y axis (indicated by Y) direction and the beam spot row 22 form an angle θ (see FIG. 2). Then, the stage driving unit 18 appropriately moves the stage 6 horizontally along the X-axis direction so that each beam spot 13 is adjusted to coincide with the start end portion of the corresponding scheduled processing line 21.

  In this state, the ceramic substrate 17 is irradiated with the laser beam from the condenser lens 5 and the Y-axis direction driving unit of the stage driving unit 18 is operated to move the stage 6 on which the workpiece is placed in the Y-axis direction. . The state in the middle is shown in FIG. When the processing of the first four scribe lines 20 is completed, the beam spot 13 is moved onto the next four scheduled processing lines 21 by the X-axis direction driving unit, and the stage 6 is moved again by the Y-axis direction driving unit. Then, the scribe line 20 is processed. This is repeated as many times as necessary to complete the processing of the scribe line 20 in the Y-axis direction.

  When processing the scribe line in the X-axis direction while the ceramic substrate 7 is installed on the same stage 6 following the end of processing of the scribe line 20 in the Y-axis direction, the X-axis is substantially the same as described above. The DOE rotating device 4 and the stage driving unit 18 are operated to perform initial adjustment so that each beam spot 13 is positioned on the starting end of the scribe line in the direction, and the scribing in the X-axis direction of the stage driving unit 18 is performed. Process the line.

As can be understood from the above, even if the distance D between the beam spots 13 of the laser beam emitted from the condenser lens 5 is a constant value, the processing line is adjusted by the rotation adjustment around the optical axis by the DOE rotating device 4. The distance d can be accurately adjusted to an arbitrary value from the fixed value to 0. The diameter of the beam spot 13 does not change.
Therefore, the laser processing apparatus 1 can easily and accurately respond to a change in the distance d of the scribe line 20 processed into the ceramic substrate 17 with a relatively simple apparatus configuration.

  A second embodiment of the present invention will be described with reference to FIGS. In this embodiment, as shown in FIG. 3, a mask plate 31 is provided in a laser processing apparatus similar to that in the first embodiment using a combination of the DOE 3 for four-divided linear array and the condensing lens 5. The laser processing apparatus 1a is provided with a mask plate rotating device 32, a shutter 33, an optical attenuator 34, and the like on the plate. These will be described below, but the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  As shown in FIG. 3, the mask plate 31 is provided at an appropriate position between the condenser lens 5 and the ceramic substrate 17 that is the object to be processed. The mask plate 31 is formed in a disc shape with a material capable of blocking the laser beam, and is supported rotatably at a position where the central axis coincides with the central axis of the condenser lens 5. As shown in FIG. 4, the mask plate 31 has four apertures 35 corresponding to the number of divided beams in this case, along the predetermined diameter line, as shown in FIG. The apertures 35 are formed in a line at intervals corresponding to D, and the apertures 35 are formed in such a size that the divided laser beams 30 can pass through the corresponding apertures 35 with a little margin.

  A gear plate 36 is formed on the outer periphery of the mask plate 31, and a mask plate rotating device 32 having a pinion 37 meshed with the gear 36 is provided. By this mask plate rotating device 32, when the DOE 3 is rotated, the mask plate 31 is rotated around the central axis of the lens 5 by the same rotation angle in the same direction in conjunction with the rotation of the DOE 3. In other words, when the DOE 3 is rotated to rotate the row of the divided beams 30 toward the respective processing points, the mask plate 31 always rotates in the same manner as the rotation, and as shown in FIG. The laser beam 30 thus made can always pass through the corresponding aperture 35 in the same manner.

  The mask plate 31 is provided with a shutter 33 for each aperture 35 as shown in FIG. The shutter 33 includes a light shielding plate 38 and a drive unit 39 using, for example, a rotary solenoid that drives the light shielding plate 38, and the laser beam 30 passing through the mask plate 31 can be selectively turned on and off individually. Is.

  Further, as shown in FIG. 6, the mask plate 31 is provided with an optical attenuator 34 detachably attached to its aperture 35. As the optical attenuator 34, for example, a partial reflector for laser light on which a dielectric multilayer film is deposited is used.

The laser processing apparatus 1a configured as described above can be used in the same manner as the apparatus of the first embodiment with the shutter 33 opened and the optical attenuator 34 removed. However, the mask plate 31 is present, and the apertures 35 that allow the divided beams 30 to pass through are arranged at equal intervals in a straight line at intervals of the distance D determined by the above-described equation (1). The noise light 40 generated in the middle of the branch spot by the laser dividing DOE 3 is blocked by the mask plate 31 and does not reach the processing point. Therefore, it is possible to prevent unscheduled processing due to noise components. FIG. 4 and FIG. 6 schematically show the situation.
Further, since the mask plate 31 rotates in the same direction and the same angle as the DOE 3 rotates, the positional relationship between the aperture 35 of the mask plate 31 and the laser beam 30 is always kept constant, and the laser beam 30 is applied to the mask plate 31. There is no blocking.
Further, since the shutter 33 is provided, the on / off state of the laser beam 30 passing through the mask plate 31 is controlled by controlling the position of the light shielding plate 38 with the driving unit 39. As a result, as shown in FIG. 5, the pitch of the machining line can be easily doubled by turning off the laser beams 30 every other time.
Further, since the laser light attenuator 34 can change the laser power between when it is attached and when it is removed, the processing depth of the scribe process can be controlled.

In the first and second embodiments, the configuration in which the DOE and the condensing lens are combined separately has been described. However, a single DOE having both a beam splitting function and a condensing function may be used.
Further, in multi-beam processing, the beam may be moved using a galvanometer or the like instead of moving the object to be processed using an XY stage.
In addition to the linear one-dimensional array, the split beam array may be a planar two-dimensional array.
In addition to the YAG laser, all other lasers used for laser processing can be used as the laser.

  In the first and second embodiments, the present invention is applied to a ceramic scriber for performing a scribe line process for dividing a chip resistor ceramic substrate into individual chips. For patterning equipment that performs scribe line processing on ITO film and amorphous silicon film for this purpose, and laser annealing that applies laser light to amorphous silicon to form laser beam on amorphous silicon to modify it into polysilicon. it can.

It is explanatory drawing which shows Example 1 of this invention typically. It is explanatory drawing which can adjust the space | interval d of a process line when processing a scribe line with the apparatus of the Example by changing angle (theta). It is explanatory drawing which shows typically the principal part of Example 2 of this invention. It is a schematic perspective view which shows the mask board and drive part of the Example. It is a schematic perspective view which shows the mask board and shutter of the Example. It is a longitudinal cross-section enlarged partial view along the aperture row | line | column of the mask board of the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Laser oscillation part 3 DOE
4 DOE Rotating Device 5 Condensing Lens 6 Stage 10 Laser Oscillator 11 Beam Expander 12 (Single) Laser Beam 12a (Divided) Laser Beam 13 Beam Spot 14 Dichroic Mirror 15 CCD Camera 16 Top Surface 17 Ceramic Substrate 18 Stage Drive Section 19 Laser processing line 20 Scribe line 21 Scheduled processing line 22 Beam spot array 24 Reflector 30 (Divided) beam 31 Mask plate 32 Mask plate rotating device 33 Shutter 34 Light attenuator 35 Aperture 36 Gear 37 Pinion 38 Light shielding plate 39 Drive unit 40 Noise light

Claims (4)

A single laser beam is divided into a plurality of laser beams using a diffractive optical element or a combination of a diffractive optical element and a condensing lens, and the plurality of lasers are moved by relatively moving the laser beam and the workpiece. In a laser processing apparatus for simultaneously processing a plurality of lines by a beam, the diffractive optical element is rotated around the optical axis, and the pitch interval of the processing lines is adjusted by adjusting the rotation angle. Laser processing equipment. Between the diffractive optical element or the combination of the diffractive optical element and a condensing lens, and a laser processing point on the processing object, and having a plurality of apertures through which a plurality of divided laser beams pass, The laser processing apparatus according to claim 1, further comprising a mask plate that rotates about the central axis in the same rotation direction with respect to the rotation of the diffractive optical element. The laser processing apparatus according to claim 2, wherein each aperture of the mask plate is provided with a mechanical or optical shutter. 4. The laser processing apparatus according to claim 2, wherein an optical attenuator for adjusting transmission power of each divided beam is provided in each aperture of the mask plate.

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