JP2004098116A - Mask transfer laser pattern machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask transfer pattern laser machining method enabling a highly precise pattern machining such as a boring which requires comparatively high energy density unlike a laser marking. <P>SOLUTION: A pulse type laser beam emitted by a laser oscillator is irradiated to a mask with an aperture of any pattern, and the laser beam which passes through the aperture of the mask is converged onto a workpiece to be machined transferring the pattern of the aperture of the mask for machining. In the mask transfer laser pattern machining method, the pulse type laser beam is scanned over the mask overlapping a portion of cross section of the laser beam for every pulse by a scanner installed on the optical axis between the laser oscillator and the mask while scanning position is moved for every pulse. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mask transfer type laser processing method for performing processing by transferring the shape of a mask onto a workpiece.
[0002]
[Prior art]
As a processing method using laser light, a mask having an arbitrarily shaped opening is arranged on the optical axis of the laser light, and the shape of the opening of the mask is transferred onto the workpiece by irradiating the mask with laser light. There is a mask transfer type laser processing method in which processing is performed at
[0003]
FIG. 5 is a block diagram showing a conventional laser marking apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 5-237673.
In the figure, the laser light oscillated from the pulse laser oscillator 21 is shaped by the beam shaping optical system 22 and then positioned at an arbitrary position on the mask 25, so that it is scanned by the galvanometer 23 in the X axis direction and the Y axis direction. Then, the light becomes parallel light through the collimator lens 24 and is emitted to the mask 25.
The laser beam masked by the mask 25 is scanned in the X-axis direction and the Y-axis direction by the positioning galvanometer 26 in order to position it at the processing position on the processing surface 29, and the processing surface 29 is processed via the objective lens 7. The position is irradiated.
The computer control unit 28 controls the pulse laser oscillator 21 and the galvanometers 23 and 26, respectively, and as shown in FIG. 6, the laser beam transmitting unit 25b is painted with a laser beam a of several tens of shots to perform marking processing.
[0004]
As other conventional laser marking apparatuses, there are JP-A-2-251387, JP-A-2-15887, and the like. Similarly, JP-A-2001-150158 discloses a processing method for straining a ceramic plate. is there.
[0005]
[Problems to be solved by the invention]
The conventional laser processing described in FIG. 5 and the prior art relates to a so-called laser marking apparatus that needs to transfer many shapes in a short time such as engraving characters. In the processing by the laser marking apparatus, surface layer ink is used. Since only a relatively low energy density is required because it is simply removed or altered, no adjustment is made to increase the energy density, and the mask is simply scanned so as to fill the mask as shown in FIG. Is doing the transcription.
Regarding the marking process, the above-mentioned processing apparatus / processing method may be used. However, in the shape processing such as drilling that requires a higher energy density than the simple laser marking, the energy density required for the processing is the first. Therefore, the size of the laser beam must be adjusted so that the laser beam can be obtained, and then the laser beam should be irradiated onto the work piece as uniformly as possible in consideration of thermal effects.
Without adjusting the size of the laser beam to increase the energy density as was done with conventional laser marking devices, simply scanning with galvano and simply painting out the intensity of the laser beam applied to the workpiece Non-uniformity occurs, which may be a problem depending on the processing content.
[0006]
Specifically, if the above-described laser marking device processing method is applied to shape processing of difficult-to-process materials that require high energy density, which is the subject of the present invention, the energy density is insufficient for processing. Based on the concept of simple painting shown in the prior art, painting a predetermined mask, controlling the galvano after processing at that position, moving to another area of the predetermined mask, and processing as if all areas were filled It becomes.
If processing is performed in this way, the energy density is insufficient, so that the processing does not progress efficiently, only the thermal effect is accumulated in the workpiece, and it is simply painted, so the intensity of the laser beam is reduced. Inhomogeneity is inevitable, and these effects cause shape accuracy defects.
[0007]
The present invention has been made in view of the problems of the conventional mask transfer laser processing method as described above, and is for performing shape processing such as drilling that requires a relatively high energy density other than laser marking with high accuracy. An object of the present invention is to provide a mask transfer type laser shape processing method.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, a laser processing method according to a first aspect of the present invention is directed to irradiating a mask having an arbitrary-shaped opening portion with a pulsed laser beam emitted from a laser oscillator. In the mask transfer type laser shape processing method for performing processing by transferring the shape of the opening of the mask onto the workpiece by condensing the laser beam that has passed through the opening of the laser on the workpiece, The pulsed laser beam is scanned on the mask so that a part of the cross section of the laser beam overlaps every pulse by a scanner provided on the optical axis between the mask and the scanning position. It is moved for each pulse.
[0009]
The energy density of the laser beam emitted from the laser oscillator is adjusted by an optical mechanism provided on the optical axis between the laser oscillator and the scanner.
[0010]
Further, the overlapping of the cross sections for each pulse of the laser light emitted from the laser oscillator is scanned within a range of 3 to 30%.
[0011]
Further, the laser beam emitted from the laser oscillator is formed into a substantially rectangular cross-sectional shape by the aperture.
[0012]
Further, when the laser beam scans the mask portion to be processed, the mask opening is circulated and scanned a plurality of times.
[0013]
Further, when the mask is scanned by the scanner, the deflection angle of the scanner is set to 30 mrad or less.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the mask transfer type laser shape processing method of the present invention will be described.
FIG. 1 is a configuration diagram of an apparatus to which a mask transfer type laser shape processing method according to an embodiment of the present invention is applied.
In the figure, 1 is a laser oscillator that generates pulsed laser light, 2 is laser light, 3 is an imaging lens having a focal length f, 4 is a workpiece, and 5 is a mask having an arbitrary mask shape. Is a letter “E” -shaped mask shape whose size is larger than the beam cross section of the irradiated laser beam 2.
6 is a reflection mirror, 7 is a galvano scanner arranged on the optical axis between the laser oscillator 1 and the mask 5, 8 is an XY table for moving the workpiece 4, 9 is the laser oscillator 1, galvano scanner 7, A control device 10 for controlling the XY table 8 is an optical mechanism for adjusting the energy density by adjusting the size of the laser beam 2.
[0015]
Next, the operation will be described.
Laser light 2 emitted from the laser oscillator 1 is reflected toward the mask 5 by a galvano scanner 7 disposed on the optical axis between the laser oscillator 1 and the mask 5.
At this time, the laser beam 2 is emitted as a laser beam 2 having a substantially rectangular cross section by a rectangular aperture 18 provided between the resonator mirror 17 in the laser oscillator 1 as shown in FIG. 10 is adjusted so as to obtain an energy density required for processing.
The galvanometer scanner 7 is constituted by, for example, two galvanometer scanners so that the laser beam 2 having a substantially rectangular cross section can be scanned two-dimensionally with respect to the mask 5.
Here, the distance between the mask 5 and the imaging lens 3 is A, the distance between the imaging lens 3 and the workpiece 4 is B, and the mask 5, the imaging lens 3 and the workpiece 4 are
1 / f = 1 / A + 1 / B
By arranging in such a positional relationship, the shape of the opening of the mask 5 is transferred to the workpiece.
[0016]
FIG. 3 shows a method of scanning the laser beam 2 onto the mask 5 by the galvano scanner 7.
The laser beam 2 having a substantially rectangular cross-sectional shape is sequentially scanned over the entire mask shape by the galvano scanner 7 in the order of S1, S2, S3,.
At this time, irradiation is performed so that a part of the beam cross section overlaps at a portion irradiated adjacently.
If the amount of overlap is too small or too large, the energy density on the workpiece will be non-uniform and the shape accuracy will be reduced.
[0017]
In FIG. 4, a carbon dioxide laser is used for a polyimide material that requires a relatively high energy density, and the amount of overlap of the laser beam 2 having a substantially rectangular cross-sectional shape with respect to the rectangular width W is changed. The difference in shape accuracy when drilling and transfer processing is performed is schematically shown.
The size of the laser beam is adjusted in advance by the optical mechanism 10 disposed in front of the mask 5 so that the energy density of the laser beam in the substantially rectangular cross section is 5 J / cm ² suitable for processing polyimide.
As shown in the figure, when the overlap amount is 3% or less with respect to the width W of the rectangle, a convex portion is seen in the outline as shown in (a), while in 30% or more, a thin part is shown as shown in (c). As shown in (b), almost good shape accuracy was obtained from the results of actual machining when the overlap amount was in the range of 3 to 30%.
As described above, in shape processing such as drilling using a mask, a difference in processing accuracy occurs due to a difference in the amount of overlap of laser beams, and scanning is performed so that the mask 5 is simply painted with the laser beam 2 as in the past. Only by doing this, it is difficult to perform transfer processing with such good shape accuracy due to non-uniformity of the intensity of the laser beam.
[0018]
Further, in the shape processing when the material is thick, it is necessary to irradiate the same place with a plurality of shots of laser light. For this purpose, the overlapping amount in the range of 3 to 30% is synchronized with the pulse, and S1, S2, When irradiation is performed in the order of S3... And the entire mask is irradiated, irradiation from S1 is performed again in the same manner, and laser irradiation corresponding to a plurality of shots is performed by repeating this operation a plurality of times.
By adopting a method of irradiating while traveling in this way, the thermal effect on the workpiece is mitigated compared to the case where scanning is performed while irradiating the same location with a plurality of shots, and processing with good shape accuracy becomes possible.
[0019]
Further, when the galvano scanner 7 is arranged in front of the mask 5, when the galvano scanner 7 has a large deflection angle, the laser beam 2 is incident on the mask 5 at an angle, so the laser beam 2 that has passed through the mask 5 diverges. Resulting in.
In order to prevent this, a conventional laser marking apparatus or the like is configured so that laser light is incident on the mask perpendicularly by providing a relay lens between the galvano scanner and the mask.
However, this relay lens is not necessary when the deflection angle of the galvano scanner is small because the divergence of the laser beam is small, and if it is used at a small deflection angle, the relay lens becomes unnecessary and the apparatus can be constructed at low cost.
In addition, the deflection angle required to scan one mask may be small, and if it is used within a deflection angle range of several tens of mrad or less, the influence of the divergence of the laser beam can be ignored, and it is expensive between the galvano scanner and the mask. A relay lens and a collimation lens need not be provided, and the apparatus can be configured at low cost.
According to an experiment conducted by the inventor, for example, when scanning a mask that fits in a 15 mm square, the distance between the galvano scanner 7 and the mask 5 is separated by 500 mm so that the deflection angle of the galvano scanner 7 is 30 mrad or less. If it is used for the transfer, sufficiently practical transfer processing is possible without using a relay lens.
[0020]
According to this embodiment, the energy density necessary for processing can be secured without using an expensive pulse laser oscillator that can output high energy, and the intensity of laser light generated due to the manner of laser light irradiation can be ensured. Transfer of masks with a relatively large area to difficult-to-work materials that require high energy density without being affected by the lack of heat or the influence of heat, without depending on the size of the laser beam. Can be performed with high accuracy.
In addition, since the necessary energy density is secured by adjusting the size of the laser beam by the optical mechanism, it is not necessary to use an expensive pulse laser oscillator that can output high energy.
Furthermore, since the laser irradiation position is changed for each pulse during shape processing, the influence of heat input can be suppressed to a minimum, and high-quality processing can be performed.
[0021]
【The invention's effect】
As described above, according to the mask transfer type laser shape processing method according to the present invention, it is possible to use a mask having an opening of an arbitrary shape with high accuracy in shape processing such as drilling that requires a relatively high energy density. The shape processing can be performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an apparatus to which a mask transfer laser processing method of the present invention is applied.
FIG. 2 is a schematic view of a method of obtaining a rectangular laser beam in the mask transfer laser processing method of the present invention.
FIG. 3 is a schematic view showing a laser scanning method of the mask transfer type laser processing method of the present invention.
FIG. 4 is a schematic diagram showing a processing result when the overlapping amount of laser beams is changed by the mask transfer type laser processing method of the present invention.
FIG. 5 is a diagram of a conventional mask transfer type laser processing method.
FIG. 6 is a diagram showing an example of processing using a conventional mask.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser oscillator, 2 Laser beam, 3 Imaging lens, 4 Workpiece, 5 Mask, 6 Reflecting mirror, 7 Galvano scanner, 8 XY table, 9 Control apparatus, 10 Optical mechanism, 17 Resonator mirror, 18 Rectangular aperture.

Claims (6)

The mask is formed by irradiating a mask having an arbitrary-shaped opening with pulsed laser light emitted from a laser oscillator, and condensing the laser light that has passed through the opening of the mask onto a workpiece. In the mask transfer type laser shape processing method for transferring the shape of the opening of the substrate to the workpiece and performing processing,
The scanner is provided on the optical axis between the laser oscillator and the mask, and the pulsed laser light is scanned on the mask so that a part of the cross section of the laser light overlaps every pulse. A mask transfer type laser processing method, wherein the scanning position is moved for each pulse. 2. The mask transfer according to claim 1, wherein the energy density of laser light emitted from a laser oscillator is adjusted by an optical mechanism provided on an optical axis between the laser oscillator and the scanner. Laser shape processing method. 3. The mask transfer type laser shape processing method according to claim 2, wherein scanning is performed in a range of 3 to 30% of overlapping of cross sections per pulse of the laser light emitted from the laser oscillator. 4. The mask transfer laser shape processing method according to claim 3, wherein the laser light emitted from the laser oscillator is formed into a substantially rectangular cross-sectional shape by an aperture. The mask transfer type laser shape processing according to any one of claims 1 to 4, wherein when the laser beam scans a mask portion to be shape-processed, the opening of the mask is scanned a plurality of times. Method. 6. The mask transfer type laser shape processing method according to claim 1, wherein a deflection angle of the scanner is set to 30 mrad or less during scanning of the mask by the scanner.

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