JPS605395B2 - Laser processing equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a scissor processing device.

FIG. 1 shows an outline of a conventional laser processing device. A laser beam 2 oscillated by a laser oscillator 1 is reflected by a mirror 3, directed downward, and condensed by a lens 4, and is irradiated onto a workpiece 5 placed near its focal point to process it. Figure 2 shows the details of the processed part. The laser beam 2 focused by the lens 4 heats, melts, and vaporizes a portion 6 of the workpiece 5 to remove it. At this time, vapor 7 of the removed substance and scattered particles 8, 9, 10 are generated which are ejected in the form of particles. A part of the ejected material adheres to the condenser lens 4 as shown in 10. Further, the other part 9 of the ejected material adheres to the workpiece again. In addition, a portion of the vapor 7 adheres to the condenser lens 4 and the workpiece 5. Such deposits cause the following adverse effects. The substance adhering to the lens 4 contaminates the lens 4, lowering the light focusing property and reducing the processing ability during laser processing. '2} When processing IC wafers, resistance circuits, etc., deposits on them may cause short circuits, deterioration of insulation properties, and deterioration of bonding properties of electrode parts, resulting in deterioration of device characteristics. . As mentioned above, the laser processing method has the disadvantage that vapor and ejected matter adhere to the lens and the workpiece, but as a countermeasure to this problem, the following methods have conventionally been taken. That is, FIG. 3 shows a method for preventing the adhesion of flying objects by blowing air. The air blown out from the nozzle 11 forms an air curtain between the shines 4 and the workpiece 5, catches the blown out steam and scattered objects, and enters the suction port 12. However, according to this method, turbulence occurs in the flow of air, making it impossible to completely capture vapor or flying objects. Furthermore, there was a drawback that the temperature, temperature, blowing, pressure, etc. of the air adversely affected the laser processing characteristics such as the processed shape and the amount removed by processing. Further, in FIG. 4, there is a tape 13 made of a material transparent to the laser beam between the lens 4 and the workpiece 5, and the ejected air particles are blocked by this tape and do not reach the lens 4. Further, since some of the vapor scattering particles adhere to the tape 13, adhesion to the workpiece 5 is avoided.
Further, the tape 13 is sent out by the roller 14 and wound up by the roller 15, so that the part of the tape with the deposits is taken up by the roller, so that the clean part is always used, and the ejected matter that has adhered to the tape is removed. does not interfere with processing. However, if the transparent tape 13 is inserted between the condensing lens 4 and the workpiece 5, the convergence of the laser beam changes, making it impossible to perform laser processing efficiently. It is difficult to prevent the particles from adhering to the workpiece. Further, in the case of tape, it is necessary to replace it, and if, for example, a tape winding and delivery mechanism were used to sequentially supply new parts, the apparatus would be complicated. Further, as shown in FIG. 5, a device for removing scattered substances generated from a workpiece so that they do not adhere to the workpiece is known from Japanese Patent Application Laid-Open No. 48-29096.

That is, an electrode 16 is provided between the lens 4 and the workpiece 5, and a voltage from a DC voltage source 18 is applied between the workpiece 5 and the electrode 16 via a protective resistor 17. and electrode 1
An electric field from the workpiece 5 to the electrode 16 is created in the space 19 between the workpiece 6 and the positively charged flying object 20 flying out from the processing section 6.
, 21, 22 are bent in the scattering direction by this electric field and captured by the electrode 16.

In other words, since the electric lines of force generated from the workpiece 5 terminate at the electrode 16, the scattered objects 21 flying out from the processing section 6 toward the lenses 4 bend their flying direction along this electric field. and reaches the electrode 16 and adheres thereto. Therefore, the amount of flying debris adhering to the lens 4 is reduced by two rivers, and since the flying debris is accelerated by this electric field, the amount of flying debris 22 adhering to the vicinity of the processed portion 6 is also reduced. However, this device has a problem in that flying objects that meet a certain launch angle and initial velocity are carried by the accelerating electric field and reach the lens 4 as they are.

The purpose of the present invention is to solve the problems of the prior art, to remove flying debris generated from the processing area during laser processing, and to accurately prevent these flying debris from adhering to lenses and workpieces. The object of the present invention is to provide a laser processing device that achieves the following.

That is, the present invention is an apparatus for laser processing by focusing a laser beam onto a workpiece using a condensing lens, in which a high potential having a polarity opposite to the charge of scattered particles flying out from the workpiece is generated between the workpiece and the workpiece. A second electrode is applied between the first electrode to which a potential of the same polarity with respect to the charge of the flying object is applied to the workpiece, and a potential of the opposite polarity to the charging of the flying object is applied. A third electrode applied between the workpiece and the objective condenser lens is installed in sequence from the condenser lens side between the objective condenser lens and the workpiece, and the scattering generated from the workpiece is removed by the first electrode. The second electrode decelerates the flying object caught by the first electrode so that it does not adhere to the objective condenser lens, and the third electrode catches the flying object that is repelled by the second electrode. The present invention is characterized in that in this way, flying objects are prevented from adhering to the objective condenser lens and the workpiece.

The present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 6 is a diagram showing an embodiment of the laser processing apparatus of the present invention.

That is, the electrode 16 is placed on the lens side between the lens 4 and the workpiece 5.
A voltage from a DC voltage source 18 is applied between the workpiece 5 and the electrode 16 via the protective resistor 17, and a voltage from the workpiece 5 to the electrode 16 is applied to the space 19 between the workpiece 5 and the electrode 16. An electric field is created toward the electrode 16, and the scattered objects flying out from the processing section 6 are captured by the electrode 16 by this electric field. However, the flying objects that meet a certain launch angle and initial velocity will be carried by the accelerating electric field and will reach the lens 4 as they are. Therefore, in order to reduce the scattered particles adhering to the lens 4, a donut-shaped metal plate, that is, an auxiliary electrode, has a hole on the inside of the center hole of the electrode 16, or slightly ahead of the center hole on the side of the workpiece, through which the laser beam 2 passes. 2
3 is placed and connected to a DC voltage 25 via a protective resistor 24.
The workpiece 5 is kept at a negative potential (a potential coexisting with the charge of the flying object). As a result, the processing section 6
In the upper space 11, there is a counterattack field formed by the auxiliary electrode 23 toward the workpiece 4, and in the obliquely upper space 26 of the processing section 6, there is a counterattack field formed by the electrode 16 from the workpiece 5. There is an electric field directed towards electrode 16. That is, among the scattered objects flying out from the processing section 6, those heading towards the lens 4 will travel in the reverse electric field and will be decelerated and will not reach the lens 4. Therefore, the number of flying objects adhering to the lens 4 is reduced. Further, a donut-shaped metal plate, that is, an auxiliary electrode 27 having a hole slightly larger than the center hole of the auxiliary electrode 23 is provided below the auxiliary electrode 23 on the side of the workpiece, and this is connected to a DC voltage 29 via a protective resistor 28. The workpiece 5 is kept at a positive potential (a potential of opposite polarity to the charge of the flying object).

In other words, the auxiliary electrode 27 is provided to reduce the amount of scattered matter that is pushed back by the reverse electric field formed by the auxiliary electrode 23 and reattaches to the workpiece 5 . In this way, the auxiliary electrodes 23 and 27 are placed under the electrode 16.
By providing the auxiliary electrode 23, it is possible to significantly reduce the amount of scattered objects that are accelerated toward the lens 4, and conversely, it is possible to reduce the amount of scattered objects that are pushed back by the auxiliary electrode 23 and prevent them from adhering to the workpiece 5. can.

Incidentally, the auxiliary electrode 23 may be a doughnut-shaped mesh or a disc-shaped mesh without a hole in the center depending on the case.

Further, FIG. 7 is a diagram showing another embodiment of the present invention.

That is, mesh electrodes I6', 23', 27' are used as electrodes.
Although some of the laser light does not reach the processing area due to light scattering by the mesh, it is possible to significantly improve the ability to capture scattered objects. Particularly, according to such an embodiment, the removal efficiency of scattered objects can be increased as much as possible by increasing the applied electric field strength.

In addition, there is no need to insert any substance between the workpiece and the lens that would have a significant effect, and there is no turbulence such as air, so the focusing ability of the laser beam is not affected, and the processing efficiency is almost negligible. , or not at all. Further, no noise is generated and the mechanism can be simplified. As explained above, according to the present invention, it is possible to reliably capture the scattered objects flying out from the workpiece and significantly reduce the amount of the objects sticking to the lens or the workpiece. Brief Description of the Drawings Fig. 1 is an explanatory diagram showing the laser processing device, Fig. 2 is an explanatory diagram showing the generation of scattered objects and steam around the processing section in the laser processing device shown in Fig. 1, and Fig. 3 Figure 4 is an explanatory diagram of a conventional technique in which flying debris is removed using an air curtain, Figure 4 is an explanatory diagram of a secondary technology in which a transparent tape is inserted between the workpiece and the lens to remove flying debris, and Figure 5 is an illustration of a conventional technology in which flying debris is removed by using an air curtain. FIG. 6 is a configuration diagram showing an embodiment of the laser processing apparatus of the present invention, and FIG. It is a figure showing another example.

2... Laser beam, 4... Lens, 5... Workpiece, 16... Electrode, 17, 24, 28...
...Protection resistor, 18,25,29...DC voltage source, 23,27...Auxiliary electrode.

O/Figure Spear 2 3 outside boxes Next 4 figures Footprint 5 Mine et al. House 7

Claims (1)

[Claims] 1. In a device that performs laser processing by concentrating a laser beam onto a workpiece using a condenser lens, a high potential with a polarity opposite to the charging of scattered particles flying out from the workpiece is applied to the workpiece. a first electrode applied between the workpiece and the workpiece, and a second electrode to which a potential of the same polarity as the charge of the flying object is applied between the workpiece and the workpiece;
A third electrode, to which a potential of opposite polarity to the charge of the flying object was applied between the third electrode and the workpiece, was installed between the objective condenser lens and the workpiece in order from the condenser lens side. A laser processing device characterized by the following. 2. The laser processing apparatus according to claim 1, wherein at least one of the first, second, and third electrodes is a mesh electrode made of a conductive material.