JPH09192875A - Laser beam machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform excellent laser beam machining even when the soot is generated from a work during the machining by holding the work with a face to be machined faced downward, and irradiating the laser beam on the face to be machined from the lower side of the work to perform the laser beam machining. SOLUTION: A mask 3 having the beam-transmission pattern similar to a pattern to be machined on a work 7 is irradiated with the laser beam LB in the ultraviolet region oscillated from a laser beam source 1 such as excimer laser after the laser beam is shaped in appropriate beam shape by a beam shaper 2. The laser beam LB transmitting the mask 3 is reflected by a dichroic mirror 4, and reflected by reflecting mirrors 11a, 11b after passing an objective lens 6, and the work 7 is irradiated therewith, and an image of equal size or the contracted size of the pattern of the mask 3 is formed on the work 7. Because the work 7 is irradiated from the lower side thereof with the laser beam LB, particulates 35 such as soot to be generated on the lower surface of the work 7 automatically fall.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus utilizing ablation by laser light in the ultraviolet region such as excimer laser.

[0002]

2. Description of the Related Art As an apparatus for finely processing a polymer material or a ceramic material, there is a laser processing apparatus using a laser beam in the ultraviolet region obtained by an excimer laser or the like.

For example, a KrF excimer laser has a wavelength of 24
The ultraviolet light of 8 nm is generated, and the ArF excimer laser generates vacuum ultraviolet light of wavelength 193 nm, and the photon energy of these ultraviolet rays corresponds to the binding energy of atoms.
Further, the excimer laser can instantaneously generate a large energy of several hundreds of millijoules or more with a pulse width of several tens of nanoseconds. When such a laser beam is applied to a work piece made of a polymer material or the like, ablation (photochemical reaction)
As a result, the intermolecular bond of the material forming the workpiece is broken, and the material is evaporated and scattered to perform the processing. Laser processing using this ablation is different from laser processing using laser light in the infrared region such as carbon dioxide gas laser.
This has an advantage that processing can be performed without thermally affecting the workpiece. By the way, in the conventional laser processing apparatus, the workpiece is held on the stage, and the processing surface of the workpiece is irradiated with laser light from above to perform the processing.

[0004]

In the laser processing utilizing ablation, a carbon-containing material such as a polymer material is irradiated with laser light to destroy the intermolecular bond of the material irradiated with the laser light. Since the processing is performed by so-called processing, soot and fine removed matter are generated from the portion irradiated with the laser beam.

As shown in FIG. 5A, when the soot 42 to 45 generated during laser processing adheres to the processing surface 41 of the workpiece 40, the soot 42 to 45 absorbs the laser beam LB. Therefore, the processing speed becomes slow in the portion where the soot 42 to 45 adhere, and as the processing progresses, as shown in FIG.
As shown in FIG. 3, there is a problem that unevenness is generated on the processed surface 41 or the contour of the processing is disturbed, and uniform processing cannot be performed. The present invention has been made in view of the above problems of the prior art, and it is an object of the present invention to provide a laser processing apparatus capable of performing excellent laser processing even if soot is generated from a workpiece during processing. To aim.

[0006]

According to the present invention, a work piece is held with the work surface facing downward, and laser light is applied to the work surface from below the work piece to perform laser processing. To achieve the above objectives.

Since the machined surface is open on the lower side and the laser machining is performed from the lower surface of the workpiece toward the inside, the soot generated during the laser machining can fall down by its own weight. . Therefore, since soot does not adhere to the laser processing surface, the processing laser light is not absorbed by soot, and uniform laser processing having a contour as designed can be realized.

That is, the present invention comprises a light source for emitting a laser beam in the ultraviolet region, a holding means for holding a work piece, and an irradiation optical system for irradiating the work piece held by the holding means with the laser light. In the laser processing apparatus having the above, the holding means holds the processed surface of the workpiece downward, and the irradiation optical system irradiates the workpiece with laser light from the lower side.

In order to prevent the generation of soot or the like dropped from the work piece due to the irradiation of the laser beam from floating in the atmosphere and contaminating the optical system of the apparatus, etc. It is preferable to provide a suction means for vacuum-sucking a product such as soot. Further, by further providing a means for blowing a gas onto the processed surface of the workpiece, particularly the laser light irradiation region,
Soot generated during laser processing can be effectively removed from the processed surface, and uniform processing can be performed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating an embodiment of the present invention. The laser beam LB in the ultraviolet region oscillated from the laser light source 1 such as an excimer laser is emitted by the beam shaping unit 2
Is shaped into an appropriate beam shape by the
The mask 3 having a light transmission pattern similar to the pattern to be processed is irradiated. The laser beam LB that has passed through the mask 3 is reflected by the dichroic mirror 4, passes through the objective lens 6, and then is reflected by the reflection mirrors 11 a and 11 b to irradiate the workpiece 7, and the laser beam LB on the workpiece 7 is reflected. A 1: 1 image or a reduced image of the pattern is formed. Mask 3
Is arranged at a position conjugate with the processing surface of the workpiece 7 with respect to the objective lens 6.

The workpiece 7 is fixed to the lower surface side of the stage 8. The workpiece 7 is fixed to the stage 8 by, for example, as shown in FIG. 2A, a fixing member 25 is provided on one end side of the lower surface of the stage 8 and a movable member 26 is provided on the other end side of the lower surface of the stage 8. This can be done by placing the object 7. The movable member 26 is pressed against the end surface of the workpiece 7 by the force of the springs 27 and 28, and the workpiece 7 is sandwiched and fixed between the fixed member 25 and the movable member 26. Alternatively, as shown in FIG. 2B, the workpiece 7 is fixed on the stage 8 by cutting the workpiece 7 placed on the stage 8 into a cross section L at both ends.
The fixing member 3 is held down by the character-shaped fixing members 31 and 32.
Alternatively, the method of fixing 1, 32 to the stage 8 with screws 33 or the like may be used.

The stage 8 can be moved in a two-dimensional direction by a driving device such as a motor 21. The movable mirror 22 is fixed to the stage 8, and the coordinate position of the stage 8 is detected by measuring the distance between the movable mirror 22 and the laser interferometer 23. The control unit 9 drives the motor 21 so that the coordinate position of the stage 8 becomes a value input in advance while monitoring the output of the laser interferometer 23.
The workpiece 7 is positioned with respect to the processing laser beam LB.
Although not shown, the stage 8 also has a rotating mechanism for rotating the workpiece on the stage, and the workpiece 7 is controlled by the controller 9
Is translated or rotated under the control of.

The irradiation energy density is set by the laser light source 1 as follows. First, the motor 21 is driven to move the stage 8 so that the energy meter 5a provided on the stage 8 is at the irradiation position of the processing laser beam LB. The laser light source 1 is driven in this state, and the energy of one pulse of the processing laser light LB (unit:
Joule). The control unit 9 calculates the irradiation energy density from the area of the irradiation pattern which is known in advance. Then, the control unit 9 sets the irradiation energy density by adjusting the output of the laser light source 1 so that the irradiation energy density applied to the processed surface of the workpiece becomes the calculated predetermined value. Since the energy meter 5a cannot be used during processing, the irradiation energy is monitored by another energy meter 5b on which the laser light transmitted through the dichroic mirror 4 is incident. The control unit 9 feedback-controls the output of the laser light source 1 using the signal from the energy meter 5b, or issues an alarm or issues a command to stop processing when the energy stability of the laser light source 1 is poor. .

FIG. 3 shows an enlarged view of the workpiece during laser processing. According to the present invention, the processing surface of the workpiece 7 faces downward, and the processing laser beam LB is applied to the workpiece from the lower side. Therefore, the fine particles 35 such as soot generated at the laser light irradiation portion of the workpiece 7 are separated from the processing portion without being deposited on the processing portion as in the conventional case, and fall down by its own weight, and are automatically processed. Removed from the surface. Therefore, unlike the conventional example described with reference to FIG. 5, soot does not adhere to the processing surface and interferes with the laser processing, and processing having a contour as designed can be uniformly performed.

At this time, as shown in FIG. 3, if a gas suction device 37 is arranged near the laser light irradiation part to suck the generated substances 35 such as soot falling from the processing part, the gas suction device 37 and the gas irradiation device 37 are sucked. It is possible to prevent the generated product 35 from floating in the atmosphere and adhering to the optical system or contaminating other parts of the device.

Further, as shown in FIG. 4, the gas suction device 3
7, the gas blowing nozzle 38 is arranged on the side opposite to the gas suction device 37 with respect to the laser beam irradiation part, and the workpiece 7
If an inert gas such as helium gas or nitrogen gas is blown to the processed portion of the laser at an appropriate flow rate, the laser beam LB
It is possible to surely remove the soot and other generated substances 35 from the irradiation portion of (1) and perform favorable laser processing. When the flow rate of the gas blown from the gas blowing nozzle 38 to the laser beam irradiation portion is too large, the generated substances 35 are scattered instead. Therefore, in an actual form, the gas spray nozzle 38 is configured so that the sprayed gas is the gas suction device 3
The blowing flow rate, the blowing direction, etc. are set in consideration of the position and the suction amount of the gas suction means 37 so that the entire amount is sucked by 7.

Returning to FIG. 1, when observing the processing surface of the workpiece 7, the observation light IB emitted from the observation light source 10 is reflected by the reflection mirror 11c, and the processing laser light LB is passed through the dichroic mirror 4 and the objective lens 6. This is performed by irradiating the processing area of the workpiece 7 coaxially, capturing the reflected light in the CCD camera 12, and observing it on the TV monitor 14.

The image processing apparatus 13 can perform processing such as storage and search of an image captured by the CCD camera 12, and search and position measurement of an alignment mark previously formed on the workpiece 7. You can The control unit 9 uses the signal from the image processing device 13 to drive the motor 21.
Thus, the stage 8 can be driven to perform rotation correction and alignment of the workpiece 7.

[0019]

According to the present invention, even if soot is generated during processing, it is not affected by soot and uniform and excellent laser processing can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic view of a laser processing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a method of fixing a work piece to a stage.

FIG. 3 is an enlarged view of a workpiece during laser processing.

FIG. 4 is an enlarged view of a workpiece during laser processing.

FIG. 5 is a diagram illustrating a problem of a conventional example.

[Explanation of symbols]

1 ... Laser light source, 2 ... Beam shaping unit, 3 ... Mask, 4 ...
Dichroic mirror, 5a, 5b ... Energy meter, 6 ... Objective lens, 7 ... Workpiece, 8 ... Stage, 9
... Control unit, 10 ... Observation light source, 11a, 11b, 11c ...
Reflection mirror, 12 ... CCD camera, 13 ... Image processing device, 14 ... TV monitor, 25 ... Fixed member, 26 ... Movable member, 27, 28 ... Spring, 31, 32 ... Fixing member, 3
3 ... screw, 35 ... generation object, 37 ... gas suction means, 38 ...
Gas blowing nozzle, 40 ... Workpiece, 41 ... Processing surface,
42, 43, 44, 45 ... Soot, LB ... Processing laser light,
IB ... Observation light

Claims (3)

[Claims] 1. A laser having a light source for emitting a laser beam in the ultraviolet range, a holding means for holding a work piece, and an irradiation optical system for irradiating the work piece held by the holding means with the laser light. In the processing apparatus, the holding means holds the processing surface of the workpiece downward, and the irradiation optical system irradiates the workpiece with the laser beam from the lower side. apparatus. 2. The laser processing apparatus according to claim 1, further comprising suction means for sucking a product generated from the workpiece by the irradiation of the laser light. 3. The laser processing apparatus according to claim 2, further comprising means for blowing gas onto the processing surface of the workpiece.