KR102627053B1 - Laser beam machining device - Google Patents

Abstract

Even when the device is shaken, precision can be maintained, and laser processing can be performed even when the device is shaken, thereby improving productivity. An illumination optical system that irradiates the mask with line-shaped processing laser light and simultaneously scans the mask with a scanning mechanism, a projection optical system that irradiates the processing laser light that has passed through the mask to the workpiece, and A support on which the illumination optical system, mask supporter, projection optical system and workpiece placing table are fixed so that the workpiece is placed and simultaneously displaced with the workpiece placing table that moves the workpiece in the x-y direction. Wow, it is a laser processing device equipped with a vibration damping device that suppresses vibration of the support.

Description

Laser processing device {LASER BEAM MACHINING DEVICE}

The present invention relates to a laser processing device that scans a line-shaped laser light against a mask and processes a substrate with the light passing through the mask. In particular, the optical positional relationship is changed by vibration. This was done to prevent misalignment.

A workpiece (workpiece, for example, a resin layer of a printed circuit board) made of a non-metallic material such as resin or silicon is scanned with laser light along a line that has passed through the mask, thereby transforming the workpiece into the pattern of the mask. It is known to perform ablation processing (removal processing by melting and evaporation) on shapes (e.g., vias) (see, for example, Patent Document 1). In addition, line-shaped laser light refers to laser light whose cross-sectional shape of the light beam in a plane orthogonal to the optical axis is line-shaped. In a package board, a type of printed wiring board, interlayer connections of wiring are performed using vias. Additionally, the via diameter ranges from several tens of micrometers to several micrometers. When the via diameter is small and precise processing is required, processing is performed by ablation using an excimer laser (KrF laser, wavelength 248 nm).

In the laser processing device of Patent Document 1, the irradiation position of the laser light is fixed and the mask is moved. Additionally, the printed board 1 is fixed on a table 13 that is free to move in a direction parallel to the moving direction of the mask. During processing, the mask 11 and the printed board 1 are moved in opposite directions relative to the fixed laser beam, so that the conductor pattern formed on the mask 11 is reduced and transferred to the printed board 1.

In addition, the laser processing device described in Patent Document 2 scans a linear beam having the same width or greater in the longitudinal direction with respect to the contact mask 14-2 in the uniaxial direction, thereby forming a printed wiring board ( 20) is designed to scan the processing area. For example, this is realized by moving the reflection mirror 13 in the L-axis direction. The processing area of the printed wiring board 20 is moved by the x-y stage mechanism 30.

[Patent Document 1] Japanese Patent Application Publication No. 2001-079678 [Patent Document 2] Japanese Patent Application Publication No. 2008-147242

In the configuration of Patent Document 1, the laser irradiation position is fixed, but vibration occurs due to movement of the mask and movement of the table 13. In the case of Patent Document 2, vibration occurs in the scanning mechanism of the reflection mirror 13, the x-y stage mechanism 30, etc. However, since neither Patent Documents 1 nor 2 take measures against vibration, there was a risk that processing accuracy would deteriorate. In other words, vibration or a change in the center of the device occurs as the scanning mechanism or processing stage moves. Accordingly, the illumination optical system, the mask, the projection optical system, and the substrate each vibrate at different movement amounts, causing an error in the projection position of the mask pattern. For this reason, it is necessary to wait for the vibration to converge before starting processing, but productivity decreases by that time. In particular, when the vibration isolation mechanism is a passive vibration isolation device, it takes time for the vibration to converge. When an active vibration isolation device is used, vibration is reduced, but the device is expensive.

Therefore, the purpose of the present invention is to provide a laser processing device that prevents a decrease in processing precision or productivity due to fluctuation.

The present invention includes an illumination optical system that irradiates a mask with a line-shaped processing laser light and at the same time scans the mask by a scanning mechanism, a projection optical system that irradiates the processing laser light that has passed through the mask onto a workpiece, and the workpiece is mounted on the workpiece. A workpiece placing table that moves the workpiece in the x-y direction while moving it, and a support to which the illumination optical system, mask supporter, projection optical system, and workpiece placing table are fixed so that they can be moved as one body. Wow, it is a laser processing device equipped with a vibration damping device that suppresses vibration of the support.

According to at least one embodiment, the present invention can maintain precision even when the laser processing device is shaken (vibrated), and can perform laser processing even when the laser processing device is shaken, thereby improving productivity. In addition, the effects described herein are not necessarily limited, and may be any one effect described herein or an effect heterogeneous therewith.

[Figure 1] Figure 1 is a diagram showing the schematic configuration of a laser processing device to which the present invention can be applied.
[Figure 2] Figure 2 is a front view of one embodiment of the present invention.
[Figure 3] Figure 3 is a perspective view of one embodiment of the present invention.
[Figure 4] Figure 4 is a schematic diagram used to explain the beam position correction unit in one embodiment of the present invention.
[Figure 5] Figure 5 is an enlarged perspective view used to explain a reflection mirror used in one embodiment of the present invention.
[Figure 6] Figure 6 is an enlarged plan view of an example of a substrate used in one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the embodiments described below are preferred specific examples of the present invention, and the content of the present invention is not limited to these embodiments.

1 is a schematic configuration diagram of an example of a processing device to which the present invention can be applied, for example, a laser processing device. The laser processing device has a laser light source (11). The laser light source 11 is, for example, an excimer laser light source that pulses KrF excimer laser light with a wavelength of 248 nm. Laser light is supplied to a line shape laser scanning mechanism 12.

The line laser scanning mechanism 12 includes an illumination optical system that shapes the laser beam into a rectangular shape (line shape, for example, 100 × 0.1 (mm)), and a line laser beam (LB). ) has a scanning mechanism (direct-acting mechanism) for scanning the mask 13. The line laser scanning mechanism 12 is displaced in the x direction.

On the mask 13, a mask pattern corresponding to the processing pattern to be formed by ablation on the workpiece (hereinafter appropriately referred to as the substrate W) is formed. That is, a pattern using a light-shielding film (for example, a Cr film) that blocks the KrF excimer laser is drawn on a substrate (for example, quartz glass) that transmits the KrF excimer laser. Processing patterns include through vias, non-through vias, and grooves for wiring patterns. After a processing pattern is formed by ablation processing, a conductor such as copper is filled.

Line-shaped laser light LB that passes through the mask 13 is incident on the projection optical system 14. Line-shaped laser light emitted from the projection optical system 14 is irradiated onto the surface of the substrate W. The projection optical system 14 has a focal plane on the mask surface and the surface of the substrate W. The substrate W is, for example, 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 thereon.

The substrate W is provided with a plurality of pattern areas WA and is fixed on a placement table 15 for placing a workpiece. By displacing and rotating the placement table 15 in the x-y direction, it is possible to position the pattern areas WA with respect to the mask 13, respectively. Additionally, in order to enable processing of the area to be processed over the entire substrate W, the placement table 15 moves the substrate W step by step in the scanning direction, for example, the x direction.

In the laser processing device described above, vibration occurs in the laser processing device during the scanning operation of the line laser scanning mechanism 12 and during the displacement operation of the placement table 15 in the x-y direction. Due to this vibration, the line laser light LB does not scan correctly on the mask 13 or the substrate W, resulting in pattern shape errors or irregularities in the amount of irradiation energy. In the embodiment of the present invention, a vibration isolation device is provided to suppress vibration of the laser processing device due to such vibration.

One embodiment of the present invention will be described with reference to FIGS. 2 and 3. The laser processing device is mounted on a base part 21 and an upper frame 22 that constitute the support. The upper frame 22 is fixed on the base portion 21. The base portion 21 and the upper frame 22 are made of a material that has high rigidity and has characteristics of damping vibration. A vibration isolation device 23 is installed between the base portion 21 and the floor. As the vibration isolation device 23, for example, a passive type vibration isolation device is used. The base portion 21 and the upper frame 22 are capable of swinging with the vibration damping device 23 as a starting point.

With respect to the upper frame 22, a line-shaped laser scanning mechanism consisting of a scanning mechanism 16 and an illumination optical system 17, a mask stage 18 (mask support portion) on which the mask 13 is mounted, and a projection optical system ( 14) is fixed. The placement table 15 is fixed on the base portion 21. That is, these scanning mechanisms 16, illumination optical system 17, mask stage 18, projection optical system 14, and placement table 15 maintain a predetermined optical relationship (processing laser light with respect to the illumination optical system 17). The base portion 21 and the upper frame 22 are positioned to satisfy the correct incidence relationship, and after positioning, according to the scanning operation of the illumination optical system 17 and the vibration due to the displacement operation of the mounting table 15, etc. In this case of fluctuation, it is made to displace as a whole. This fluctuation is suppressed by the vibration suppression device 23, but cannot be completely eliminated, so the incident position and incident angle of the processing laser light 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 housing 24 installed separately from the base portion 21 and the upper frame 22. The laser light source 11 pulses a KrF excimer laser (referred to as processing laser light) (L1) with a wavelength of 248 nm. Additionally, it has a guide beam light source 25 that generates guide laser light L2 for laser position adjustment. The processing laser light L1 and the guide laser light L2 have parallel optical paths at predetermined intervals.

The processing laser light L1 and the guide laser light L2 are incident on the beam position correction unit (referred to as a beam steering mechanism) 27. The beam position correction unit 27 is a mechanism for determining the position (position and angle of incidence) of the processing laser light L1 in real time.

Figure 4 shows an example of the beam position correction unit 27. A first adjustment mirror 28 is installed on the laser light source 11 side. The processing laser light (L1) and the guiding laser light (L2) reflected from the first adjustment mirror (28) are transmitted through the pipe (29) to a second adjustment mirror mounted on the base portion (21) or upper frame (22). Joined the company at (30). The processing laser light L1 reflected from the second adjustment mirror 30 is reflected from the mirror 33 and is incident on the illumination optical system 17.

The guide laser light L2 reflected from the second adjustment mirror 30 is split into two optical paths at the beam splitter 31 and enters the sensor 32. The sensor 32 is mounted on the base portion 21 or the upper frame 22 and has a position sensor that detects the position from two diverged guide laser beams and an angle sensor that detects the angle. As a position sensor and an angle sensor, for example, a Position Sensitive Detector (PSD) is used. The first adjustment mirror 28 and the second adjustment mirror 30 are capable of adjusting the angles of the mirrors in two axes by using two actuators. This actuator is feedback controlled by the detection signal from the sensor 32.

That is, it is equipped with a processing device that processes the signal from the sensor 32 (position sensor, angle sensor), and feeds it back to the actuator that drives the first adjustment mirror and the second adjustment mirror, so that the base portion 21 of the laser processing device ) and the inclination of the upper frame 22, the processing laser light is adjusted so that the processing laser light always enters the illumination optical system 17 at the correct position and angle.

For the first adjustment mirror 28 and the second adjustment mirror 30, both the processing laser light L1 having a wavelength of, for example, 248 nm and the guiding laser light L2 having a wavelength of, for example, 400 nm to 700 nm. joins the company. In order to reflect two laser lights with greatly different wavelengths, two different types of reflection films are formed on the first adjustment mirror 28 and the second adjustment mirror 30.

As shown in FIG. 5, the first adjustment mirror 28 and the second adjustment mirror 30 have a boundary ( It is formed separately from B). In Figure 5, a spot 43 of laser light for processing and a spot 44 of laser light for guidance that are incident on each area are shown. The distance between the processing laser light and the guide laser light is set so that the spots 43 and 44 do not enter the area of another reflective film.

The processing laser light L1 reflected from the second adjustment mirror 30 is incident on the illumination optical system 17. The illumination optical system 17 has an optical unit that equalizes the intensity distribution of the light emitted from the laser light source and transforms it into line-shaped laser light for processing. The illumination optical system 17 includes a lens array 17b (first optical element) that expands light in one direction (Y direction), and reduces light in a direction perpendicular to the expansion direction of the first optical element. It is equipped with an optical unit 17a having second optical elements arranged in a line. The first optical element is a lens array in which a plurality of lenses are arranged in the direction in which light expands. That is, the optical unit 17a includes a lens system (not shown) that converts the magnified light into parallel light, and a lens system (17c) that reduces the parallel light to a direction orthogonal to the magnification direction of the lens array (X direction when viewed from the mask). ) (second optical element). The optical unit 17a shapes the beam of laser light into a line beam and guides the line laser light LB to the mask 13. For example, it is shaped into a line-shaped laser light LB with a length of 100 mm and a vertical direction of 0.1 mm.

The scanning mechanism 16 is a part of the illumination optical system 17 and moves the entire illumination optical system including the optical unit 17a. The optical unit 17a slides on a trestle along the scanning direction (x-direction) to reciprocate the optical unit 17a. As the optical unit 17a moves, the line-shaped laser light LB moves with respect to the mask 13, and the mask 13 and the substrate W fixed to the mask stage 18 and the placement table 15, respectively. ) is scanned with laser light for processing.

In the case of a configuration using a conventional shifting reflective mirror, the shape of the laser light for processing changes as the reflective mirror moves. As a result, uniform strength distribution throughout the processing range is not obtained, and processing results vary depending on the location. In this way, when scanning laser light for processing on a line, there is a problem that the line shape cannot be scanned with high precision (so that the shape is not deformed during scanning). According to one embodiment of the present invention, because the laser light on the line does not deform upon scanning, processing precision can be improved.

The mask 13 forms a blocking film (chromium film, aluminum film, etc.) that blocks the KrF excimer laser light on a substrate (for example, quartz glass) that transmits the KrF excimer laser light, thereby drawing a mask pattern. It is becoming. A pattern that appears repeatedly on the substrate W may be drawn on the mask 13, or a pattern spanning the entire substrate W may be drawn.

The mask stage 18 holds the mask 13 and is equipped with an xyθ stage capable of positioning the mask. A camera (not shown) is provided to read the alignment mark provided on the mask 13 and determine the position of the mask 13.

The processing laser light that passes through the mask 13 is incident on the projection optical system 14. The projection optical system 14 is a projection optical system that focuses on the surface of the mask 13 and the surface of the substrate W, and projects the light passing through the mask 13 onto the substrate W. Here, the projection optical system 14 is configured as a reduction projection optical system (for example, 1/4 times).

The placement table 15 fixes the substrate W by vacuum suction or the like, and at the same time positions the substrate W with respect to the mask 13 by moving and rotating in the x-y direction by a table moving mechanism. In addition, step movement is possible along the scanning direction (here, x-direction) so that ablation processing can be performed over the entire substrate W. Next to the placement table 15, an alignment camera (not shown) is installed to capture an image of an alignment mark provided on the substrate W. Additionally, a z mechanism for focus adjustment, etc. may be installed.

The substrate W (workpiece) is, for example, an organic substrate for a printed wiring board, and a layer to be laser processed is formed on the surface. The layer to be processed is, for example, a resin film or metal foil, and is formed of a material that can be processed such as via formation by laser light. Vias and wiring patterns are formed using a laser processing machine, and in the subsequent process, the processed portion is filled with a conductor such as copper.

Figure 6 shows an enlarged example of the substrate W. The substrate W is a multi-faceted substrate, and on the substrate W, a pattern area WA corresponding to the pattern of the mask 13 is repeated in an (8×8) matrix shape. So it is installed. In Figure 6, the x-direction is the sub-step direction and the y-direction is the main step direction. When a pattern area WA is scanned, the next pattern area is scanned. Additionally, the scanning direction (arrow) depicted is an example.

In addition, in one embodiment of the present invention, although not depicted, a conveyance mechanism is provided, and the workpiece is placed on or removed from the placement table by the conveyance mechanism. For example, a scalar robot, etc. can be used. It is also equipped with an unpainted air conditioning chamber that covers the housing of the processing device and the laser light source.

In one embodiment of the present invention described above, a control device (not shown) is provided to control the entire device. The control device controls the laser light source 11, controls each part of the drive unit, aligns the mask and the substrate W, manages production information, and manages recipes.

Although one embodiment of the present technology has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications are possible based on the technical idea of the present invention. In addition, the configurations, methods, processes, shapes, materials, and values exemplified in the above-described embodiments are merely examples, and other configurations, methods, processes, shapes, materials, and values, etc. may be used as necessary. do.

W: Workpiece (substrate)
11: Laser light source
12: Laser scanning mechanism
13: mask
14: Projection optical system
15: wit table
16: injection device
17: Illumination optical system
18: Mask Stage
25: Guide beam light source
27: Beam position correction unit
32: sensor

Claims (6)

An illumination optical system that irradiates a mask with a line-shaped processing laser light and simultaneously scans the mask with a scanning mechanism;
a projection optical system that irradiates the processing laser light that has passed through the mask onto a workpiece;
a workpiece placing table that moves the workpiece in the xy direction while the workpiece is placed thereon;
a support on which the illumination optical system, the mask support, the projection optical system, and the workpiece placing table are fixed so as to be displaced integrally;
Equipped with a vibration damping device that suppresses vibration of the support,
A laser processing device in which the illumination optical system emits the processing laser light in a line, and the scanning mechanism linearly displaces the processing laser light in a direction perpendicular to the line direction. delete According to paragraph 1,
A laser light source that generates the laser light for processing is installed separately from the support,
A laser processing device in which the incident position and incident angle of the processing laser light with respect to the illumination optical system are controlled to be predetermined by a beam position correction unit. According to claim 1 or 3,
A laser light source that generates the processing laser light and a guide laser light for position adjustment of the processing laser light is installed separately from the support,
The processing laser light is incident on the illumination optical system,
The processing laser light and the guide laser light are supplied to the beam position correction unit,
A laser processing device in which the incident position and incident angle of the processing laser light on the illumination optical system are corrected to predetermined values by the beam position correction unit based on the guide laser light. According to clause 4,
The beam position correction unit has at least one optical element,
The optical element is,
A laser processing device wherein surface treatment corresponding to the processing laser light and surface treatment corresponding to the guiding laser light are performed on one surface. According to paragraph 1,
A laser processing device, wherein a workpiece placement table intermittently moves in the line direction to sequentially process a plurality of regions of the workpiece.

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