JP2009050869A - Laser beam machining method and laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining technology capable of rapidly machining a workpiece without using any water, and beautifully finishing a machined surface of the workpiece. <P>SOLUTION: The laser beam machining apparatus 10 comprises: a first laser beam oscillator 12 for outputting the first laser beam L1 having a relatively short wavelength; a beam rotator 16 which performs the rotational deflection of the first laser beam L1 to move the irradiation spot on the surface of a workpiece 52 along a circumference 54; a second laser beam oscillator 20 for outputting the second laser beam L2 of a relatively long wavelength; and a mixing mirror 18 for applying the second laser beam L2 to a vicinity of a center of a circumference 54 on the surface of the workpiece 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing technique, and more particularly to a laser processing method and a laser processing apparatus suitable for processing such as cutting and drilling using a laser beam on a workpiece.

  When a work such as cutting is performed on a workpiece such as a semiconductor wafer, as shown in Non-Patent Document 1, a blade cut method has been mainly used so far. This is a mechanism in which a workpiece is mechanically cut by a dicer or a slicer, and accordingly, there has been a problem that chipping easily occurs due to chip mounting.

  On the other hand, a laser microjet dicing method has recently appeared as a technique for cutting a workpiece without contact. This is for processing a workpiece with a laser beam guided by a water jet water flow, and has the advantage that the occurrence of chipping is suppressed because the mechanical load can be greatly reduced.

  Furthermore, as a method of laser processing, as shown in Non-Patent Document 2, a processing method using a beam rotator has been proposed. This is because a laser beam with a relatively short wavelength, such as a UV laser or green laser suitable for micromachining, is deflected in a circular shape via a beam rotator, and the irradiation spot on the surface of the workpiece is moved to draw a circular orbit. This is a technique for forming a circular opening. The workpiece can be cut by moving the circular opening linearly.

Laser / Microjet Adhesive Tape (Furukawa Electric Time Report) Internet URL: http://furukawa.jp/jiho/fj110/fj110_21.pdf Search Date: July 23, 2007 Kataoka Manufacturing Co., Ltd./Processing example / Drilling using a beam rotator Internet URL: http://www.kataoka-ss.co.jp/product/kakou06.html Search date: July 23, 2007

  Certainly, according to the above-mentioned laser / microjet dicing method, the mechanical load on the workpiece can be greatly reduced, so that the occurrence of chipping can be suppressed compared to the blade cutting method, and the cutting speed can be improved. I can expect. However, since a large amount of water is inevitably used for cutting, there is a problem that it cannot be used for cutting a workpiece with low water resistance.

  On the other hand, in the case of the laser processing method using the beam rotator, since water is not used for processing, there is an advantage that the range of processing objects is widened. In addition, since a relatively short wavelength laser beam such as a UV laser or a green laser is used, there is an advantage that the finished surface is smooth. On the other hand, UV lasers and green lasers generally have a drawback that it is difficult to obtain a large output, and the processing time becomes long.

  The present invention has been devised to solve the above-described problems of conventional laser processing methods, and can process a workpiece at high speed without using water, and can also smoothly finish the processing surface. It aims at realizing the laser processing technology that can be used.

  In order to achieve the above object, in the laser processing method according to the present invention, the first laser beam having a relatively short wavelength emitted from the first laser oscillator is rotated and deflected so that the irradiation spot on the workpiece surface is set to the circumference. And a step of irradiating the second laser beam having a relatively long wavelength emitted from the second laser oscillator near the center of the circumference of the workpiece surface.

  The laser processing apparatus according to the present invention also includes a first laser oscillator that outputs a first laser beam having a relatively short wavelength, and rotationally deflects the first laser beam, thereby circularly irradiating an irradiation spot on the workpiece surface. , A second laser oscillator for outputting a second laser beam having a relatively long wavelength, and transmission means for irradiating the second laser beam near the center of the circumference on the workpiece surface It is characterized by having.

According to the laser processing method and the laser processing apparatus according to the present invention, the first laser beam having a relatively short wavelength is irradiated on the workpiece surface so as to draw a circular shape, so that a smooth through-hole is formed on the processed surface. Is possible. In addition, since the second laser beam is radiated to the vicinity of the center of the circumference with a relatively long wavelength and easy to increase the output, processing by the first laser beam is promoted, and only the first laser beam is used. As a result, the machining speed can be dramatically increased as compared with the case of machining.
Moreover, since it is a dry process that does not use any water, it can be effectively applied to a work with low water resistance.

  FIG. 1 is a schematic diagram showing a basic configuration of a laser processing apparatus 10 according to the present invention, and a first laser oscillator 12 for outputting a first laser beam L1 for fine processing, and a first light condensing. A lens 14, a beam rotator 16, a mixing mirror 18, a second laser oscillator 20 for outputting a second laser beam L2 for high-speed processing, a first collimating lens 22, a beam splitter 24, A second condenser lens 26, a laser nozzle 28, a third condenser lens 30, a light receiving element 32 such as a CCD, and a personal computer 34 are provided.

As the first laser beam L1, a green laser, a UV laser, or the like that can smoothly finish the processed surface with a relatively short wavelength (for example, 532 nm wavelength) is selected. As the output of the first laser beam L1, for example, a relatively low output of 5 to 30 W can be selected.
Further, as the second laser beam L2, for example, a fiber laser, a Dd: YAG laser, or the like having a relatively long wavelength (for example, 1064 nm wavelength) and a high output (for example, 100 to 200 W) is selected.

  The beam rotator 16 has a first rotating optical system 36, a second collimating lens 38, and a second rotating optical system 40. The first rotating optical system 36 includes a pair of wedge prisms 42, 44, and the wedge prisms 42, 44 are arranged so as to be adjustable in an arbitrary direction. The second rotating optical system 40 also includes a pair of wedge prisms 46 and 48, and the wedge prisms 46 and 48 are disposed so as to be adjustable in an arbitrary direction. The first rotating optical system 36 and the second rotating optical system 40 are installed so as to be independently rotatable at high speed by a motor (not shown).

The mixing mirror 18 has a characteristic of transmitting the first laser beam L1 incident on the first surface 18a and reflecting the second laser beam L2 incident on the second surface 18b.
The beam splitter 24 has a characteristic of transmitting the second laser beam L2 incident on the first surface 24a and reflecting the visible light α incident on the second surface 24b.

  The upper opening of the laser nozzle 28 is closed by the second condenser lens 26. Further, a branch pipe 50 is provided on a side surface of the laser nozzle 28, and a mechanism is provided in which high-pressure air is supplied from the branch pipe 50 into the laser nozzle 28.

Next, a processing method using the laser processing apparatus 10 will be described.
First, with the first rotating optical system 36 and the second rotating optical system 40 of the beam rotator 16 rotated at a high speed, the first laser beam L1 and the second laser beam L2 are output.

The first laser beam L 1 emitted from the first laser oscillator 12 is condensed by the first condenser lens 14 and enters the beam rotator 16. Then, after being rotationally deflected by the first beam rotator 16 so as to move on the circumference, it passes through the first surface 18a of the mixing mirror 18.
As a result, as shown in FIG. 2, the irradiation spot 53 of the first laser beam L 1 moves along the circumference 54 on the surface of the workpiece (semiconductor wafer, glass, quartz, etc.) 52. The spot diameter of the first laser beam L1 is set to 30 μm or less, for example.

The second laser beam L 2 emitted from the second laser oscillator 20 is collimated by the first collimating lens 22, then passes through the beam splitter 24, and passes through the second surface 18 b of the mixing mirror 18. Reflected in the direction of the workpiece 52.
At this time, the second laser beam L2 is guided by the mixing mirror 18 so as to irradiate the central portion of the circumference 54. The spot diameter of the second laser beam L2 is set to 100 μm or more, for example.

As a result, a circular through hole 56 is formed on the surface of the workpiece 52. As shown in FIG. 1, the through hole 56 has a reverse tapered shape in cross section.
By moving the irradiation spot of each laser beam in a linear manner by the action of an XY stage (not shown) or the like as it is, a cutting line 58 is formed on the surface of the work 52 and the cutting of the work 52 is realized.

At the time of processing, high pressure air is supplied from the branch pipe 50 into the laser nozzle 28 and discharged from the lower end opening 60 to the surface of the work 52, so that processing waste is effectively removed.
Further, the visible light α reflected by the surface of the workpiece 52 is captured by the light receiving element 32 and displayed on the screen of the personal computer 34.

  The incident angle of the first laser beam L1 with respect to the workpiece 52 can be adjusted by appropriately rotating the wedge prisms 42 and 44 in the first rotating optical system 36 and adjusting the relationship between the wedge angles between them. Thus, the taper angle of the through hole 56 can be adjusted.

  Further, by rotating the wedge prisms 46 and 48 in the second rotating optical system 40 as appropriate and adjusting the relationship between the wedge angles between them, the radius of rotation of the first laser beam L1 at the work 52 is adjusted. Therefore, the diameter of the through hole 56 formed in the workpiece 52 can be adjusted.

Since the inner surface of the through hole 56 is processed by the first laser beam L1 having a relatively short wavelength, the surface of the processed surface (cut surface) can be smoothly finished. Further, since the second laser beam L2 having a high output and a relatively long wavelength is irradiated near the center of the circumference 54, the processing by the first laser beam L1 is promoted, and the processing speed can be increased. .
In addition, since the processing is completed in a dry process that does not use any water, it can be applied to drilling or cutting a work with low water resistance (for example, a circuit board on which an element is mounted).

It is a schematic diagram which shows the basic composition of the laser processing apparatus which concerns on this invention. It is explanatory drawing which shows the processing state in the workpiece | work surface.

Explanation of symbols

10 Laser processing equipment
12 Laser oscillator
14 First condenser lens
16 Beam rotator
18 Mixing mirror
18a First side of mixing mirror
18b Second side of mixing mirror
20 Second laser oscillator
22 First collimating lens
24 Beam splitter
24a Beam splitter first side
24b Beam splitter second side
26 Second condenser lens
28 Laser nozzle
30 Third condenser lens
32 Photo detector
34 PC
36 First rotating optical system
38 Second collimating lens
40 Second rotating optical system
42 wedge prism
44 wedge prism
46 wedge prism
48 wedge prism
50 branch pipe
52 work
53 Irradiation spot of the first laser beam
54 Circumference
56 Through hole
58 Cutting line
60 Lower end opening L1 of laser nozzle First laser beam L2 Second laser beam α Visible light

Claims (2)

Rotating and deflecting the first laser beam having a relatively short wavelength emitted from the first laser oscillator, and moving the irradiation spot on the workpiece surface along the circumference;
A laser processing method comprising: irradiating a second laser beam having a relatively long wavelength emitted from a second laser oscillator near a center of a circumference of the workpiece surface. A first laser oscillator for outputting a first laser beam having a relatively short wavelength;
A beam rotator that rotationally deflects the first laser beam and moves the irradiation spot on the workpiece surface along the circumference;
A second laser oscillator for outputting a second laser beam having a relatively long wavelength;
A laser processing apparatus comprising: a transmission unit configured to irradiate the second laser beam near the center of the circumference of the workpiece surface.

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