JPH0630828B2 - Laser processing method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser processing method and an apparatus thereof, and more particularly to a laser processing method and an apparatus thereof suitable for preventing adhesion of molten droplets generated during laser processing. Regarding

[Conventional technology]

Regarding laser processing technology, for example, as described in Laser Processing, Akira Kobayashi, and Development Company (published on July 1, 1980, supplemental new edition), molten droplets adhering near the processing target during laser processing are processed. A method of ultrasonic cleaning in an organic solvent such as alcohol later is adopted in a step after laser scribing the Si semiconductor substrate. However, in reality, not all the molten droplets are removed, and it is necessary to remove the molten droplets in a separate process depending on the processing target.

On the other hand, not only laser processing but also a processing method of blowing a gas to a molten portion to be processed is well known. However, for example, in the case of an air jet, it cannot be effective depending on the size of the processing target and the mass of the molten droplet. Since it is difficult to focus the air jet if the processing target is in the range of several tens of μm,
Requires subsonic spraying. That is, the object to be processed using the air jet is usually in the range of several mm to sub-mm, which is not suitable for fine processing. If an air jet is used, not only is the laser processing apparatus increased in size, but noise is generated and the working environment is deteriorated, which is not preferable.

[Problems to be solved by the invention]

An object of the present invention is to provide a laser processing method and an apparatus therefor, in which molten droplets generated during laser processing do not adhere to an object to be processed without providing a gas blowing mechanism.

[Means for solving problems]

In the laser processing apparatus for processing the desired area by focusing and irradiating the desired area of the processing object with the laser light, an ultrasonic wave irradiating means for focusing and irradiating the desired area with ultrasonic waves. Is arranged around the optical axis of the laser light for irradiating the desired area, and at the same time as irradiating the laser light to the desired area, the desired area is superposed from the circumference of the optical axis of the laser light. This is achieved by focusing and irradiating a sound wave to prevent re-adhesion of molten droplets generated during laser processing to the object to be processed.

[Action]

Due to the laser beam applied to the processing target, the melted and evaporated material scatters to the periphery and tries to adhere to the processing target. At this time, by driving a vibration source other than the processing target, the fluid surrounding the processing region near the processing target can be vibrated. The energy of this vibration causes the molten droplet and the object to be processed to move with each other, and it is possible to prevent the droplet from firmly adhering.

〔Example〕

In the description of this embodiment, for example, a case where a coating film formed on an insulator, a pattern on a semiconductor substrate, or the like is processed with an accuracy of about μm is shown. Unless otherwise stated, the case of processing in the air is shown. However, depending on the property of the processing object (for example, water resistance is excellent), it is possible to obtain better results by carrying out the present invention in water than in air. .

First, the principle of the present invention will be described with reference to FIG. A laser beam 2 emitted from a laser oscillator 1 is condensed by a processing objective lens 3 and irradiated on a processing region 5 of a processing target 4 to perform processing. The molten droplets 6 generated at this time fall on the periphery, but if a vibrator 8 is sandwiched between the object 4 to be processed and the stage 7 and driven, the dropped droplets will fall on the surface to be processed. It does not move and adhere firmly.

The above vibration is changed to ultrasonic vibration, and a water tank (not shown) is provided on the stage according to the processing target. As a result, noise is reduced and the apparatus itself can be prevented from being large in size as compared with the conventional air jet method. Further, if the vibration is performed in the ultrasonic range, not only the attachment of the droplets can be prevented more effectively, but also the vibration energy can be easily focused (described later). As a result, there is also an effect of promoting the separation of the melted and resolidified portion.

FIG. 2 is a diagram showing an embodiment of the present invention. The components having the same reference numerals as in FIG. 1 have already been described. Reference numeral 8'denotes an ultrasonic transducer arranged so as to focus on the processing region 5. The general idea is that ultrasonic vibrations are possible from 1MHz to 50MHz and the overall diameter with the concave shape is about 20mm.
At the focal point, ultrasonic vibration energy is narrowed down to a diameter of 20 μm. If the ultrasonic transducer 8'has an output of 1 W, the energy density of about 3 × 10 ⁵ W / cm ² can be calculated in the processing region 5 by ignoring the attenuation of ultrasonic waves in air, water and other fluids. Is obtained. The relationship with the material to be processed must also be taken into consideration, but if the energy density is sufficient, the molten droplets will break up into many small spheres due to ultrasonic vibration. As a result, there is an effect that the surface area is increased and the surface area is rapidly cooled to weaken the adhesive force.

FIG. 3 shows another embodiment of the present invention. An ultrasonic transducer 8 ″ is arranged so that the molten droplet 6 is focused on the processing region 5 from slightly above the surface of the processing target 4. Further, the ultrasonic transducer 8 ″ is composed of four vibrators. And the oscillators facing each other are driven so that their phases differ by π radian.
According to the vibrator having such a configuration, the vibration energy can be further improved.

FIG. 4 is a schematic diagram showing another configuration and driving method of the ultrasonic transducer 8 ″. A cross section viewed from the optical axis direction of the laser beam 2 is shown. The ultrasonic transducers 8 ″ -n (n is a natural number up to 3) divided so as to be connected are driven so as to have a phase relationship as shown in FIGS. In the case of (a) in the figure, the phase differs by π radians, and push-pull drive is performed. In the vibrator of FIG. 6C, the 2 / 3π radian phases are different from each other, so that the rotational force indicated by the arrow 9 ′ is applied to the molten droplets. 5
By using oscillators of division or more and making the phases different, it is possible to cause the droplet to perform linear motion, circular motion, and arbitrary Lissajous pattern motion.

By combining with the embodiment shown in FIG. 1 described above, the fluid in the vicinity of the processing region 5 can be effectively vibrated, but in that case, the phase difference between the ultrasonic transducers must be considered. I won't.

〔The invention's effect〕

According to the present invention, since it is possible to prevent molten droplets from adhering during laser processing without directly applying vibration to the processing target, it is possible to realize high-quality processing with high accuracy and less adhesion of droplets around the processing portion.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a laser processing apparatus for explaining the principle of the present invention, FIG. 2 is a front view of the laser processing apparatus according to the first embodiment of the present invention, and FIG. 3 is a second view of the present invention. FIG. 4 is a front view of a laser processing apparatus according to an embodiment, and FIG. 4 is a diagram showing the relationship between the arrangement of ultrasonic transducers and the phase of vibration in the second embodiment. 8 ... Transducer, 4 ... Processing target, 5 ... Processing area, 6 ...
… Melting spray, 2 …… laser light, 7 …… table.

Claims (8)

[Claims] 1. A laser processing apparatus for processing a desired region by focusing and irradiating a desired region of a processing object with a laser beam, wherein the ultrasonic beam is focused and applied to the desired region. A laser processing apparatus, wherein a sound wave irradiating unit is arranged around an optical axis of the laser beam for irradiating the desired region. 2. The ultrasonic transducer of the ultrasonic wave irradiating means has a concave vibrating surface that forms a focal point in the desired region on the processing target. The laser processing apparatus according to item 1. 3. The ultrasonic wave irradiation means has a plurality of ultrasonic wave vibrators, and the plurality of ultrasonic wave vibrators are arranged around an optical axis of the laser beam for irradiating the desired region. The laser processing apparatus according to claim 1, wherein: 4. The laser processing apparatus according to claim 1, wherein the plurality of ultrasonic transducers are symmetrically arranged around an optical axis of the laser light. 5. A laser processing method for processing a desired region by focusing and irradiating the desired region of a processing target with the laser beam, wherein the desired region is irradiated with the laser light and at the same time the desired region is processed. A laser processing method, characterized in that the molten droplets generated during laser processing are prevented from reattaching to the object to be processed by focusing and irradiating an ultrasonic wave on the region of from around the optical axis of the laser light. . 6. The ultrasonic wave is generated from an ultrasonic vibrator having a concave vibrating surface that forms a focal point in the desired area on the object to be processed. The laser processing method according to the item. 7. The ultrasonic wave is generated from a plurality of ultrasonic vibrators arranged around the optical axis of the laser light, and is generated from adjacent ultrasonic vibrators of the plurality of ultrasonic vibrators. The laser processing method according to claim 5, wherein a rotational force about the optical axis of the laser beam is applied to the molten droplets by sequentially shifting the phases of the ultrasonic waves by equal pitches. 8. The ultrasonic waves are generated from at least one pair of ultrasonic transducers symmetrically arranged in pairs around the optical axis of the laser beam, and the ultrasonic transducers forming the pair respectively generate ultrasonic waves. The laser processing method according to claim 5, wherein the phases of the generated ultrasonic waves are deviated from each other by π radian.