CN111992893A

CN111992893A - Laser processing apparatus

Info

Publication number: CN111992893A
Application number: CN202010277835.7A
Authority: CN
Inventors: 中本裕见; 船山昌彦; 鹫山裕之
Original assignee: Orc Manufacturing Co Ltd
Current assignee: Orc Manufacturing Co Ltd
Priority date: 2019-05-27
Filing date: 2020-04-10
Publication date: 2020-11-27
Also published as: JP2020192550A; KR102627053B1; TW202042948A; JP7278868B2; KR20200136304A

Abstract

Provided is a laser processing device. Even if the device swings, the precision can be maintained, and laser processing can be performed even in a swinging state, so that the productivity is improved. A laser processing apparatus includes: an illumination optical system that irradiates a linear processing laser beam to a mask and scans the mask by a scanning mechanism; a projection optical system for irradiating the processing laser beam passing through the mask to the object to be processed; a workpiece stage for placing a workpiece and moving the workpiece in an x-y direction; a support to which the illumination optical system, the support portion of the mask, the projection optical system, and the object stage are fixed so that the illumination optical system, the support portion of the mask, the projection optical system, and the object stage are integrally displaced; and a vibration damping device that suppresses vibration of the support body.

Description

Laser processing apparatus

Technical Field

The present invention relates to a laser processing apparatus that scans a linear laser beam through a mask (mask) and processes a substrate with the laser beam passing through the mask, and more particularly, to a laser processing apparatus that prevents an optical positional relationship from being shifted by vibration.

Background

It is known that a linear laser beam transmitted through a mask is scanned over a workpiece (a workpiece, for example, a resin layer of a printed circuit board) made of a non-metal material such as resin or silicon, and ablation (ablation: removal by melting or evaporation) is performed on the workpiece to form a pattern (for example, a through hole) of the mask (for example, see patent document 1). The linear laser beam is a laser beam having a linear cross-sectional shape of a light beam on a plane perpendicular to the optical axis. In a package substrate which is one type of a printed wiring board, interlayer connection of wirings is performed using a VIA (VIA). The diameter of the through hole is several tens μm to several μm. When the through hole diameter is small and precise processing is required, processing by ablation using an Excimer laser (KrF laser, wavelength 248nm) is performed.

In the laser processing apparatus of patent document 1, the irradiation position of the laser beam is fixed, and the mask is moved. The printed circuit board 1 is fixed to a table 13, and the table 13 is movable in a direction parallel to the mask movement direction. During processing, the mask 11 and the printed board 1 are moved in opposite directions with respect to the fixed laser beam, and the conductor pattern formed on the mask 11 is transferred to the printed board 1 in a reduced size.

The laser processing apparatus described in patent document 2 scans a processing region of the printed circuit board 20 by scanning a linear beam having a size in the longitudinal direction equal to or larger than the width of the contact mask 14-2 with respect to the contact mask 14-2 in the uniaxial direction. For example, by making the mirror 13 movable in the L-axis direction. The x-y stage mechanism 30 moves the processing area of the printed wiring board 20.

Documents of the prior art

Patent document 1: japanese laid-open patent application No. 2001 and 079678

Patent document 2: japanese patent laid-open No. 2008-147242

Disclosure of Invention

[ problems to be solved by the invention ]

The structure of patent document 1 fixes the laser irradiation position, but generates vibration due to the movement of the mask and the movement of the table 13. In the case of patent document 2, vibrations are generated in the scanning mechanism of the mirror 13, the x-y stage mechanism 30, and the like. However, in both patent documents 1 and 2, no countermeasure against vibration is taken, and therefore, there is a possibility that the machining accuracy is lowered. That is, vibration occurs and the center of gravity of the apparatus changes as the scanning mechanism and the processing stage move. Accordingly, the illumination optical system, the mask, the projection optical system, and the substrate are vibrated by different amounts of movement, and thus an error occurs in the projection position of the mask pattern. Therefore, it is necessary to wait for the vibration to converge and start the machining, but the productivity is reduced corresponding to the amount of time. In particular, when the damper mechanism is a passive damper device, it takes time for the vibration to converge. In the case of using an active vibration damping device, the vibration can be reduced, but the price of the device is increased.

Accordingly, an object of the present invention is to provide a laser processing apparatus that prevents a reduction in accuracy of processing or a reduction in productivity due to wobbling.

[ means for solving the problems ]

The present invention is a laser processing apparatus including:

an illumination optical system that irradiates a linear processing laser beam to a mask and scans the mask by a scanning mechanism;

a projection optical system for irradiating the processing laser beam passing through the mask to the object to be processed;

a workpiece stage for placing a workpiece and moving the workpiece in an x-y direction;

a support body that integrally displaces the illumination optical system, the mask support portion, the projection optical system, and the workpiece stage; and

and a vibration damping device for damping vibration of the support body.

[ Effect of the invention ]

According to at least one embodiment, in the present invention, even when the laser processing apparatus has oscillated (vibrated), the laser processing can be performed even in the oscillated state while maintaining the accuracy, and therefore, the productivity can be improved. The effects described herein are not necessarily limited to these, and any one of the effects described in the present specification or effects having properties different from these effects may be used.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a laser processing apparatus to which the present invention is applicable.

Fig. 2 is a front view of an embodiment of the present invention.

Fig. 3 is a perspective view of an embodiment of the present invention.

Fig. 4 is a schematic diagram for explaining a beam position correction unit according to an embodiment of the present invention.

Fig. 5 is an enlarged perspective view for explaining a mirror used in one embodiment of the present invention.

Fig. 6 is an enlarged plan view of an example of a substrate used in one embodiment of the present invention.

Description of the reference symbols

W: a workpiece (substrate); 11: a laser light source; 12: a laser scanning mechanism; 13: a mask; 14: a projection optical system; 15: a mounting table; 16: a scanning mechanism; 17: an illumination optical system; 18: a mask stage; 25: a guided light beam source; 27: a beam position correction section; 32: a sensor.

Detailed Description

Hereinafter, embodiments and the like of the present invention will be described with reference to the drawings. The embodiments and the like described below are preferable specific examples of the present invention, and the contents of the present invention are not limited to these embodiments and the like.

Fig. 1 is a schematic configuration diagram of an example of a processing apparatus to which the present invention is applicable, for example, a laser processing apparatus. The laser processing apparatus has a laser light source 11. The laser light source 11 is, for example, an excimer laser light source that irradiates a KrF excimer laser having a wavelength of 248nm with pulses. The laser light is supplied to the linear laser scanning mechanism 12.

The linear laser scanning mechanism 12 includes: an illumination optical system that shapes a laser beam into a rectangle (linear, for example, 100 × 0.1 (mm)); and a scanning mechanism (linear motion mechanism) for scanning the mask 13 with the linear laser beam LB. The linear laser scanning mechanism 12 is displaced in the x direction.

A mask pattern corresponding to a processing pattern formed on a workpiece (hereinafter, referred to as a substrate W as appropriate) by ablation is formed on the mask 13. That is, a pattern of a light-shielding film (e.g., a Cr film) that blocks the KrF excimer laser light is drawn on a substrate (e.g., quartz glass) through which the KrF excimer laser light is transmitted. As the processing pattern, there are a through via, a non-through via, a groove (Trench) for a wiring pattern, and the like. After forming a processing pattern by ablation processing, a conductor such as copper is filled.

The linear laser beam LB having passed through the mask 13 is incident on a projection optical system 14. The linear laser beam emitted from the projection optical system 14 is irradiated to the surface of the substrate W. The projection optical system 14 has a focal plane on the mask plane and the surface of the substrate W. The substrate W is a resin substrate in which a copper wiring layer is formed on a substrate such as an epoxy resin and an insulating layer is formed on the copper wiring layer.

A plurality of pattern areas WA are provided on a substrate W fixed to a mounting table 15 for mounting a workpiece. The stage 15 is displaced and rotated in the x-y direction, whereby the pattern areas WA can be positioned with respect to the mask 13, respectively. The stage 15 is configured to move the substrate W in steps (step move) in the scanning direction, for example, in the x direction, so that the region to be processed can be processed over the entire substrate W.

In the laser processing apparatus described above, vibration is generated in the laser processing apparatus during the scanning operation of the linear laser scanning mechanism 12 and during the displacement operation of the mounting table 15 in the x-y direction. Due to this vibration, a pattern shape error or unevenness of irradiation energy occurs because the linear laser beam LB does not accurately scan the mask 13 or the substrate W. In the embodiment of the present invention, a vibration damping device is provided to suppress vibration of the laser processing apparatus due to the vibration.

An embodiment of the present invention will be described with reference to fig. 2 and 3. The laser processing apparatus is attached to a base portion 21 and an upper frame 22 constituting a support body. The upper frame 22 is fixed to the base portion 21. The base portion 21 and the upper frame 22 are made of a material having high rigidity and vibration damping properties. A damper 23 is provided between the base portion 21 and the floor surface. As the damper device 23, for example, a passive type damper device is used. The base portion 21 and the upper frame 22 can swing with the vibration damping device 23 as a starting point.

To the upper frame 22 are fixed: a linear laser scanning mechanism including a scanning mechanism 16 and an illumination optical system 17; a mask stage 18 (a mask support portion) on which the mask 13 is placed; and a projection optical system 14. The table 15 is fixed to the base portion 21. That is, the scanning mechanism 16, the illumination optical system 17, the mask stage 18, the projection optical system 14, and the stage 15 are positioned so as to satisfy a predetermined optical relationship (a relationship in which the processing laser light is accurately incident on the illumination optical system 17), and are displaced integrally when the base portion 21 and the upper frame 22 are swung by vibration or the like caused by the scanning operation of the illumination optical system 17 and the displacement operation of the stage 15 after the positioning. This wobbling is suppressed by the vibration damper 23, but cannot be completely eliminated, and therefore, the incident position and incident angle of the processing laser beam with respect to the illumination optical system 17 are corrected by the beam position correction unit 27.

The laser light source 11 is housed in a case 24, and the case 24 is provided independently of the base portion 21 and the upper frame 22. The laser light source 11 pulse-irradiates KrF excimer laser light (referred to as processing laser light) L1 having a wavelength of 248 nm. Further, a guide beam light source 25 is provided, and the guide beam light source 25 generates a guide laser beam L2 for laser position adjustment. The processing laser light L1 and the guiding laser light L2 are configured to have optical paths parallel at a predetermined interval.

The processing laser light L1 and the guiding laser light L2 enter the beam position correction unit (referred to as a beam steering mechanism) 27. The beam position correction unit 27 is a mechanism for performing positioning (position and incident angle) of the processing laser light L1 in real time.

Fig. 4 shows an example of the beam position correction unit 27. A 1 st adjustment mirror 28 is provided on one side of the laser light source 11. The processing laser light L1 reflected by the 1 st adjustment mirror 28 and the guiding laser light L2 pass through the tube (pipe)29 and enter the 2 nd adjustment mirror 30, and the 2 nd adjustment mirror 30 is attached to the base portion 21 or the upper frame 22. The processing laser light L1 reflected by the 2 nd adjustment mirror 30 is reflected by the mirror 33 and enters the illumination optical system 17.

The guiding laser light L2 reflected by the 2 nd adjustment mirror 30 is branched into two optical paths by the beam splitter 31 and enters the sensor 32. The sensor 32 includes a position sensor attached to the base portion 21 or the upper frame 22 and detecting a position by two branched guiding laser beams, and an angle sensor detecting an angle. As the Position sensor and the angle sensor, for example, a PSD (Position Sensitive Detector) is used. The 1 st adjustment mirror 28 and the 2 nd adjustment mirror 30 can adjust the angle of the mirrors in the 2 nd axis direction using two actuators. The actuator is feedback-controlled by a detection signal of the sensor 32.

That is, by providing a processing device that processes signals from the sensor 32 (position sensor and angle sensor), and feeding back actuators that drive the 1 st adjustment mirror and the 2 nd adjustment mirror, the processing laser light can be adjusted so that the processing laser light is always incident on the illumination optical system 17 at an accurate position and angle regardless of the inclination of the base portion 21 and the upper frame 22 of the laser processing device.

Both the processing laser light L1 having a wavelength of 248nm, for example, and the guiding laser light L2 having a wavelength of 400nm to 700nm, for example, enter the 1 st adjustment mirror 28 and the 2 nd adjustment mirror 30. The 1 st adjustment mirror 28 and the 2 nd adjustment mirror 30 are formed with two different reflection films to reflect two laser lights having a large difference in wavelength.

As shown in fig. 5, the 1 st adjustment mirror 28 and the 2 nd adjustment mirror 30 are formed by separating a reflection film 41 corresponding to the processing laser beam and a reflection film 42 corresponding to the guiding laser beam from each other at a boundary B. Fig. 5 shows a spot 43 of the processing laser beam and a spot 44 of the guiding laser beam incident on each region. The interval between the processing laser beam and the guiding laser beam is set so that the

spots

43 and 44 do not enter different areas of the reflective film.

The processing laser light L1 reflected by the 2 nd adjustment mirror 30 enters the illumination optical system 17. The illumination optical system 17 includes an optical unit that makes the intensity distribution of the light emitted from the laser light source uniform and deforms the processing laser light into a linear shape. The illumination optical system 17 has an optical unit 17a, and the optical unit 17a has: a lens array 17b (1 st optical element) that magnifies light in one direction (Y direction); and a 2 nd optical element which linearly reduces the light in a direction perpendicular to the enlargement direction of the 1 st optical element. The 1 st optical element is a lens array in which a plurality of lenses are arranged in a direction in which light is magnified. That is, the optical unit 17a has: a lens system (not shown) for converting the amplified light into parallel light; and a lens system 17c (2 nd optical element) that reduces the parallel light in a direction perpendicular to the magnification direction of the lens array (X direction when viewed on the mask). The optical unit 17a shapes the laser beam into a linear beam and guides the linear laser beam LB to the mask 13. The linear laser beam LB is shaped to have a longitudinal direction of 100mm and a longitudinal direction of 0.1mm, for example.

The scanning mechanism 16 is a part of the illumination optical system 17, and moves the entire illumination optical system including the optical unit 17 a. The optical unit 17a is configured to slide on the gantry along the scanning direction (x direction) and reciprocate the optical unit 17 a. The linear laser beam LB moves relative to the mask 13 in accordance with the movement of the optical unit 17a, and scans the mask 13 and the substrate W fixed to the mask stage 18 and the stage 15, respectively, with the processing laser beam.

In the case of using a conventional displacement mirror, the shape of the processing laser beam is deformed as the mirror moves. As a result, a uniform intensity distribution cannot be obtained over the entire processing range, and the processing results vary depending on the location. Thus, there are the following problems: when scanning a linear machining laser beam, it is not possible to scan the linear shape with high accuracy (so that the shape is not deformed during scanning). According to one embodiment of the present invention, since the linear laser light is not deformed during scanning, the processing accuracy can be improved.

The mask 13 is formed by forming a blocking film (e.g., a chromium film, an aluminum film, etc.) for blocking the KrF excimer laser beam on a substrate (e.g., quartz glass) through which the KrF excimer laser beam is transmitted, and thereby a mask pattern is drawn. The mask 13 may be patterned so as to repeatedly appear on the substrate W, or may be patterned over the entire substrate W.

The mask stage 18 has an xy θ stage that holds the mask 13 and can position the mask. A camera (not shown) is provided for reading the alignment marks provided on the mask 13 and positioning the mask 13.

The processing laser light having passed through the mask 13 is incident on the projection optical system 14. The projection optical system 14 is a projection optical system having a focal point on the surface of the mask 13 and the surface of the substrate W, and projects the light transmitted through the mask 13 onto the substrate W. Here, the projection optical system 14 is configured to reduce the projection optical system (for example, 1/4 times).

The stage 15 fixes the substrate W by vacuum suction or the like, and positions the substrate W with respect to the mask 13 by movement and rotation in the x-y direction by the stage moving mechanism. Further, the substrate W can be moved in steps along the scanning direction (x direction in this case) so that ablation can be performed over the entire substrate W. A calibration camera (not shown) is provided beside the mounting table 15, and the calibration camera (not shown) images a calibration mark provided on the substrate W. Further, a z mechanism for focus adjustment may be provided.

The substrate W (workpiece) is, for example, an organic substrate for a printed wiring board, and has a layer to be processed whose surface is laser-processed formed thereon. The layer to be processed is, for example, a resin film or a metal foil, and is formed of a material that can be processed by laser beam through hole formation or the like. Through holes and wiring patterns are formed by a laser processing machine, and conductors such as copper are filled in the processed portions in the subsequent steps.

Fig. 6 shows an enlarged view of an example of the substrate W. The substrate W is a multi-chamfered substrate, and a pattern area WA corresponding to the pattern of the mask 13 is repeatedly provided in a (8 × 8) matrix on the substrate W. In fig. 6, the x direction is the sub-step direction, and the y direction is the main step direction. When a certain pattern area WA is scanned, the next pattern area is scanned. The illustrated scanning direction (arrow) is an example.

In one embodiment of the present invention, although not shown, a conveying mechanism is provided, and the workpiece is placed on and removed from the mounting table by the conveying mechanism. For example, a SCARA robot (scarobot) or the like can be used. Further, an air conditioning chamber, not shown, is provided, and the air conditioning chamber covers the processing device and the housing of the laser light source.

In one embodiment of the present invention, a vibration damping device (not shown) for controlling the entire device is provided. The vibration damping device controls the laser light source 11, controls each part of the driving unit, calibrates the mask and the substrate W, manages production information, and manages recipe (recipe).

Although one embodiment of the present technology has been specifically described above, the present invention is not limited to the above-described one embodiment, and various modifications based on the technical idea of the present invention can be made. The structures, methods, steps, shapes, materials, numerical values, and the like recited in the above embodiments are merely examples, and structures, methods, steps, shapes, materials, numerical values, and the like different from those described above may be used as necessary.

Claims

1. A laser processing apparatus is characterized by comprising:

a projection optical system for irradiating the processing laser beam having passed through the mask onto a workpiece;

a workpiece stage for placing the workpiece thereon and moving the workpiece in an x-y direction;

a support to which the illumination optical system, the support portion of the mask, the projection optical system, and the object stage are fixed so that the illumination optical system, the support portion of the mask, the projection optical system, and the object stage are integrally displaced; and

and a vibration damping device that suppresses vibration of the support body.

2. Laser processing apparatus according to claim 1,

the illumination optical system emits the linear processing laser beam, and the scanning mechanism linearly displaces the processing laser beam in a direction perpendicular to the linear direction.

3. Laser processing apparatus according to claim 1 or 2,

a laser light source for generating the processing laser light is provided independently of the support,

the beam position correcting unit controls an incident position and an incident angle of the processing laser beam with respect to the illumination optical system to predetermined incident positions and predetermined incident angles.

4. Laser processing apparatus according to claim 3,

a laser light source for generating the processing laser light and the guiding laser light is provided independently of the support,

the processing laser light is incident on the illumination optical system,

the processing laser beam and the guiding laser beam are supplied to the beam position correction unit,

the beam position correcting unit corrects the incidence position and incidence angle of the processing laser beam with respect to the illumination optical system to predetermined incidence positions and incidence angles based on the guiding laser beam.

5. Laser processing apparatus according to claim 4,

the beam position correction unit includes at least one optical element that is subjected to surface treatment corresponding to the processing laser beam and surface treatment corresponding to the guiding laser beam in one plane.

6. Laser processing apparatus according to claim 2,

the workpiece stage is intermittently moved in the line direction, thereby sequentially processing a plurality of regions of the workpiece.