WO2005118207A1 - Laser beam apparatus - Google Patents

Abstract

A laser beam apparatus for processing a workpiece (20), comprising an optical system consisting of optical components for guiding a laser beam emitted from a laser oscillator (1) to the workpiece (20), wherein one laser beam is split by a first polarization splitting means (5) into two laser beams, one of the beams is passed through a mirror (14) while the other is used by a first galvano scan mirror (13) for scanning in two axial directions, the two laser beams are guided to a second polarization splitting means (8) and used by a second galvano scan mirror (12) for scanning. The first and second polarization splitting means are arranged at 45° relative to the optical axis of the laser light.

Description

 Technical details Laser processing equipment Technical field

 The present invention relates to a laser processing apparatus whose main purpose is drilling a workpiece such as a printed circuit board, and in particular, to improve productivity and processing quality. Background art

 Among laser processing apparatuses mainly used for drilling a conventional workpiece such as a pudding substrate, a laser processing apparatus capable of performing processing at two locations at the same time is, for example, an international publication number WO 0 3 The configuration as shown in FIG.

In Fig. 9, 1 is a laser oscillator, 2 is a laser beam, 3 is a mask that cuts out the laser beam of the necessary part from the incident laser beam to make the processing hole the desired size and shape, and 4 is a laser. Multiple mirrors that reflect light 2 and guide the optical path. 24 is the first polarization beam splitter that splits the laser beam 2 into two laser beams, 6 is the first laser beam split by the first polarization beam splitter 24, 6 p is the polarization direction of the laser beam 6, 7 is the other laser beam split by the first polarization beam splitter, 7 s is the polarization direction of the laser beam 7, 25 is the laser beam 6 reflected and transmitted through the laser beam 7, and the second galvanoscan mirror 1 2 is a second polarization beam splitter for guiding to 2. 10 is the laser beam reflected by the second polarizing beam splitter, 11 is the laser beam transmitted by the second polarizing beam splitter, 14 is the laser beam 6 to the second polarizing beam splitter 25 Mirror for guiding, 1 7 is laser light F 0 lens for condensing 1 0, 1 1 onto the workpiece 20, 1 3 for scanning the laser beam 7 in two directions and guiding it to the second polarizing beam splitter 25 The first galvanoscan mirrors 1 and 12 are second galvanoscan mirrors for scanning the laser beam 10 and the laser beam 11 in two axial directions and guiding them to the workpiece 20. 1 8 is an XY table for moving the workpiece 20 in the XY direction, 19 is a power sensor that measures the energy of the laser beam emitted from the f 0 lens 17, and 15 is a shield for the laser beam 6 The first shirt 1, 16 is a second shutter that blocks the laser beam 7. The power sensor 19 is fixed to the XY table 18 and can be moved to a position where the laser beam hits the light receiving part of the power sensor 19 when measuring the energy of the laser beam. .

 As shown in Fig. 9, one laser beam is split into two laser beams with a polarizing beam splitter, and the two laser beams are scanned independently, allowing drilling to be performed at two locations simultaneously. In the laser processing apparatus, the laser beam 2 oscillated by the linearly polarized light from the laser oscillator 1 is guided to the first polarization beam splitter 24 via the mask 3 and the mirror 4. Then, in the first polarization beam splitter 24, the P wave component of the laser beam 2 is transmitted through the polarization beam splitter 24 and becomes the laser beam 6, and the S wave component is reflected by the polarization beam splitter 24 and is reflected by the laser beam 7 Spectral.

 The laser beam 6 that has passed through the first polarization beam splitter 24 is guided to the second polarization beam splitter 25 via the mirror 1.

 On the other hand, the laser beam 7 reflected by the first beam splitter 24 is scanned in the biaxial direction by the first galvano scan mirror 13 and then guided to the second polarization beam splitter 25.

The laser beam 6 is always guided to the second polarization beam splitter 25 at the same position, but the laser beam 7 is swung by the first galvano scan mirror 1 3. By controlling the angle, the position and angle of incidence on the second polarizing beam splitter 25 can be adjusted.

 Thereafter, the laser beams 10 and 11 are scanned in the biaxial direction by the second galvanoscan mirror 1 1 2 and then guided to the f 0 lens 1 7, respectively, at a predetermined position of the workpiece 20. Focused.

 At this time, by scanning the first galvano scan mirror 13, the laser beam 11 can be oscillated within a set range with respect to the optical axis of the laser beam 10, for example, within a range of 4 mm square. Yes. This makes it possible to irradiate laser light to any two different points on the workpiece 20 at the same time via the second galvano scan mirror 12 that swings within a range that can be machined, for example, 50 mm square. It is said.

 FIG. 10 shows a schematic diagram for explaining the principle of the polarization beam splitter 24, showing a front view at the center, a side view at the left and right, and a top view at the top.

 In FIG. 10, 26 is the window portion of the polarization beam splitter, and in the case of a carbon dioxide laser, ZnSe and Ge are used. 27 is a mirror for turning the laser beam back to 90 °.

 The polarization beam splitter 24 has a Brewster angle with respect to the incident beam for polarization separation.

 Therefore, when the laser beam 28 enters the polarization beam splitter 24, the component with polarization direction 28p (P wave component) is transmitted and the component with polarization direction 28s (S wave component) is reflected. Have nature.

In addition, the laser beam is equally divided if it is a circularly polarized light in which all polarization directions exist uniformly, or a polarization direction that forms an angle of 45 ° to the P wave and S wave, and the energy of the laser light 29 and laser light 30 Have the property of being equal. Therefore, the incident beam 2 to the first polarizing beam splitter 2 4 is By making the angle of 45 ° to circularly polarized light, P wave, or 5 wave, energy is separated equally.

 Of course, if the polarization direction of the laser light incident on the polarization beam splitter 24 is only the P-wave component, all the laser beam is transmitted, and if only the S-wave component is reflected, the laser beam is reflected.

 Therefore, the incident beam to the second polarizing beam splitter 25 can be obtained without energy loss by making the laser beam 7 only the P wave component and the laser beam 6 only the S wave component. The galvanometer scan mirror 1 2 is used. In the conventional laser processing apparatus as described above, the incident angle of the laser beam to the window portion 26 is the pre-Easter angle for both the first polarization beam splitter 24 and the second polarization beam splitter 25. The laser beam 2 is split into S wave and P wave components by arranging the windows so that, for example, if a window made of ZnSe is used for the carbon dioxide laser spectroscopy, If the Brewster angle is 67.5 ° and the incident angle to the window is large, and the diameter of the laser beam guided to the polarizing beam splitter is φ 3 5 mm, the laser beam diameter on the window is in the major axis direction. 9 4 mm. Therefore, the window needs to have an effective diameter that is at least 2.5 times the laser beam diameter, which makes it difficult to maintain manufacturing accuracy.

In addition, the laser beam 6 transmitted as the P wave component through the first polarizing beam splitter 24 needs to be reflected as the S wave component by the second polarizing beam splitter 25. The first polarizing beam splitter 2 Since the laser beam 7 reflected by 4 as the S wave component needs to be transmitted as the P wave component in the second polarization beam splitter 25, the laser beam 9 is sent to the first and second polarization beam splitters, respectively. 0. Mira 1 to wrap to 2 7 In addition, the relative positional relationship between the window portion 2 6 and the mirror 2 7 greatly affects the accuracy of the optical path after the polarization beam splitter, so pay attention to the relative positional relationship between the window portion 2 6 and the mirror 2 7. There was also a problem that the polarizing beam splitter became a more expensive optical component because it was necessary to manufacture the polarizing beam splitter.

 In addition, in order to obtain more stable processing quality in consideration of the characteristics of the f0 lens 17, it is necessary to shorten the optical path length between the first polarization beam splitter 24 and the f0 lens 17 as much as possible. It was necessary to increase the effective diameter of the polarizing beam splitter. However, since it is difficult to design the effective diameter of the polarizing beam splitter sufficiently large, the effective diameter of the polarizing beam splitter is actually not sufficient, and the diameter of the laser beam guided to the f 0 lens 17 is the desired diameter. However, if the focal length of the f0 lens is constant, the laser beam diameter on the workpiece is greatly restricted by the desired diameter, and an optical path suitable for drilling smaller holes is formed. There is also a problem that the required processing quality cannot be obtained.

 In addition, the individual optical components used in the optical system always have distortion (convergence) in the manufacturing process, and the lower the required accuracy for flatness, the worse the yield and the higher the cost. Generally, it is manufactured with an optical distortion of about 110 to 120 of the laser wavelength λ. If an optical system that combines multiple optical components without considering these optical components is constructed, individual aberrations accumulate and astigmatism occurs, making it impossible to obtain the required processing quality. There was also a problem that there was a case.

In addition, since optical parts with flat surface shapes generally have the same manufacturing process for manufacturing the front and back surfaces, both the front and back surface shapes tend to be convex or concave. There is also a problem that the optical distortion (aberration) increases in the transmission type optical component. The present invention has been made to solve such a problem, and uses an inexpensive optical component as a polarization separation means in a laser processing apparatus that performs processing using a laser beam dispersed by the polarization separation means. The first object of the present invention is to obtain a laser processing apparatus that can reduce the diameter of the laser beam on the workpiece.

 A second object is to obtain a laser processing apparatus that can reduce the aberration due to the surface shape of the optical component and improve the processing quality. Disclosure of the invention

 In order to achieve the above object, the laser processing apparatus according to the first invention has an optical system comprising a plurality of optical components that guide the laser beam emitted from the laser oscillator to the workpiece. The laser beam is split into two laser beams by the first polarization separation means, one passes through the mirror, the other scans in the biaxial direction by the first galvano scan mirror, and the two laser beams are In the laser processing apparatus for processing a workpiece by scanning with a second galvano-scanning means, the first and second polarization-separating means are arranged with respect to the optical axis of the laser beam. It was placed at 5 °.

 In the laser processing apparatus according to the second invention, the first and second polarization separation means are polarization beam splitters having a dielectric multilayer coating formed on the surface.

 In the laser processing apparatus according to the third aspect of the invention, the first and second polarized light separating means have a concave shape on one side and a convex shape on the back side.

In the laser processing apparatus according to the fourth aspect of the invention, the first polarization separation means has a convex surface on the side that reflects the laser light and a concave shape on the back surface, and is reflected by the first polarization separation means. The surface shape of the laser beam is concave The second polarized light separating means led to the first galvano scan mirror has a concave surface on the side that reflects the laser beam and a convex surface on the back surface. ·

In the laser processing apparatus according to the fifth invention, the first polarization separation means has a concave surface on the side that reflects the laser light and a convex shape on the back surface, and is reflected by the first polarization separation means. The laser beam is guided to the first galvano scan mirror having a convex surface shape, and the second polarized light separating means has a convex surface on the side that reflects the laser light and a concave surface on the back surface. It is. _r

 In the laser processing apparatus according to the sixth aspect of the invention, the concave or convex shapes on the surfaces of the first and second polarization separation means have an accuracy of λλ20 or less when the wavelength of the laser beam is λ. Is formed.

 In the laser processing apparatus according to a seventh aspect of the present invention, in the optical system, a pair of optical components having substantially the same surface shape is used, and the beam incident surface of one optical component is perpendicular to the beam incident surface of the other optical component. In addition, the beam incident angle to one optical component is arranged to be the same as the beam incident angle to the other optical component.

 In the laser processing apparatus according to the eighth aspect of the present invention, a mask is provided in the laser beam path from the laser beam emitted from the laser oscillator to the first polarization separation unit, and the mask and the workpiece The set of optical components is placed between them.

 In the laser processing apparatus according to the ninth aspect of the present invention, the optical processing apparatus includes a holder for individually fixing the set of optical components, and when the holder has directionality, the axis indicating the directionality is set to each optical component. Are arranged in the same direction with respect to the incident surface. .

In the laser processing apparatus according to the tenth invention, the one set of optical components The surface shape is formed with an accuracy of λΖ10 to I20, where I is the wavelength of the laser beam.

 In the laser processing apparatus according to the first aspect of the invention, the first and second polarization separation means include a mechanism capable of adjusting an angle in two axial directions perpendicular to the traveling direction of the laser light and orthogonal to each other. Is.

 In the laser processing apparatus according to the 12th aspect of the invention, there is provided a damper for absorbing laser light leaking as energy loss from the second polarization separation means. According to the present invention, by using a polarization beam splitter having an incident angle of 45 ° as the polarization separating means, a laser beam having a larger diameter can be made incident on the f Θ lens. The diameter of light can be made smaller, and finer processing can be performed. In addition, the polarized light separating means is inexpensive and can reduce the cost. Brief Description of Drawings

 FIG. 1 is a block diagram of the laser processing apparatus showing Embodiment 1 of the present invention.

 FIG. 2 is a schematic view of a part of the holder for fixing the polarization beam splitter showing the first embodiment of the present invention.

 FIG. 3 is a block diagram of a laser processing apparatus showing Embodiment 2 of the present invention.

 FIG. 4 is a schematic diagram for explaining the relationship between the surface shape and refractive power of the optical component of the laser machining apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a schematic diagram for explaining the arrangement of optical components of the laser machining apparatus according to Embodiment 2 of the present invention. FIG. 6 is a schematic diagram for explaining the relationship between the refractive power and the arrangement of optical component holders having directionality of the laser processing apparatus according to the second embodiment of the present invention.

 FIG. 7 is a block diagram of a laser processing apparatus showing Embodiment 3 of the present invention.

 FIG. 8 is a schematic diagram for explaining the relationship between the surface shape and refractive power of the optical component of the laser machining apparatus according to Embodiment 3 of the present invention.

 FIG. 9 is a block diagram of a laser processing apparatus showing the prior art according to the present invention.

 FIG. 10 is a schematic diagram for explaining a polarization beam splitter of a laser processing apparatus showing the prior art according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1.

 FIG. 1 relates to Embodiment 1 of the present invention. A polarization beam splitter having an incident angle of 45 ° is used as a polarization separation means, one laser beam is split into two laser beams, and the two laser beams are independently used. FIG. 2 is a configuration diagram showing a laser processing apparatus for drilling that can perform processing at two locations simultaneously by scanning. The same components as those in FIG. 9 of the prior art are designated by the same reference numerals and detailed description thereof is omitted.

In FIG. 1, 5 is the first polarization beam splitter, 6 is the laser beam transmitted through the first polarization beam splitter 5, 6p is the P wave component for the first polarization beam splitter of laser 6, and 6 s is the polarization direction of the S-wave component for the first polarization beam splitter of the laser beam 6, 7 is the laser beam reflected from the first polarization beam splitter 5, and 7 s is the laser beam 7. For the first polarization beam splitter, the polarization direction that becomes the S wave component, 7 p Is the polarization direction that becomes the P wave component for the first polarization beam splitter of laser light 7, 8 is the second polarization beam splitter, 9 is a damper that receives the laser light generated as energy loss, and 10 is the laser. Of the light 6, the laser light reflected by the second polarizing beam splitter 8, and 11 is the laser light transmitted through the second polarizing beam splitter 8 out of the laser light 7.

 When laser light is polarized and separated in the prior art, a P-wave component that is transmitted by using a window with an incident angle as the pre-Uster angle and polarization-separating laser light that equally contains the P-wave component and S-wave component. The reflected S wave component is equally distributed, and the energy of the laser light is equally divided.

 However, in this embodiment, by using a polarizing beam splitter having a reflective surface coated with a dielectric multilayer film, for example, the incident angle is set to 45 ° with respect to the optical axis instead of the Brewster angle. Transmits the P wave with a constant accuracy, reflects the S wave with a certain accuracy, and divides the energy of the laser light equally.

As an example, a polarization beam splitter coated to transmit 95% of the P wave and 5% of the S wave and reflect 95% of the S wave and 5 <½ of the P wave will be described. . Assuming that the energy of the laser light incident on the first polarizing beam splitter 5 is 100%, the laser light 6 transmitted through the first polarizing beam splitter 5 has a P wave component of 47.5 o / o and an S wave. Contains 2.5 o / o ingredients. After that, the second polarization beam splitter 8 receives laser light including 47.5 <½ S wave component and 2.5% P wave component, and reflects the second polarization beam splitter 8. The laser beam contains 45.125% S wave component and 0.125% P wave component, and the energy of the laser beam 10 guided to the second galvanoscan mirror 12 is final. 4 5. 2 5%. The laser beam that causes energy loss through the second polarizing beam splitter 8 contains 2.375% S wave component and 2.375 o / o P wave component. 1 "1 thing.

 On the other hand, the laser beam 7 reflected from the first polarizing beam splitter 5 goes through the same process, and 45.25% of the energy is led to the second galvanoski Yanmira 1 2 and 4. 5% energy Is a loss. Therefore, a total of 9.5% is not led to the second galvanoscan mirror 1 or 2 as energy loss, but when the optical path according to the present embodiment is configured, the loss of the laser beam 6 is the second loss. Because it passes through the polarizing beam splitter and reflects the loss of the laser beam 7, all the laser beam that causes this energy loss can be collected in the part of the damper 9, and the optical components by the laser beam for the loss, etc. Can prevent damage.

 The polarizing beam splitter transmits 95% of the P wave and 5% of the S wave and reflects 95% of the S wave and 5% of the P wave at an incident angle of 45 °. However, the incident angle deviates from 45 °. In this case, the ratio of the transmitted P wave and the reflected S wave will decrease and the energy loss will increase, so it is desirable to arrange them at an incident angle of 45 °.

 In the above, the energy loss of a polarized beam splitter that transmits 95% of the P wave and 5% of the S wave and reflects 95% of the S wave and 5% of the P wave is 9.5%. As explained, it is clear that if the P-wave transmittance and S-wave reflectance are made higher than 95%, the energy loss will be smaller than 9.5%.

In addition, since the polarization beam splitter according to the present embodiment is arranged so that the incident angle of the laser beam is 45 °, if the diameter of the laser beam guided to the polarization beam splitter is ø35 mm, the laser beam diameter on the window This is 52 mm in the long axis direction, which is about 1.5 times the laser beam diameter, and the window effective diameter of a conventional polarizing beam splitter with an incident angle of Brewster angle of at least 2.5 times the incident laser beam diameter. Compared to existing products, they can be manufactured in smaller shapes. You can. Compared with the area of the window, the minor axis direction can be 35 mm in all directions, so the polarization beam splitter with an incident angle of 45 ° can reduce the area by 44.6% compared to the conventional polarization beam splitter. . This makes it possible to reduce the size of the processing apparatus.

 In the case of a window with the same diameter, for example, 53 mm, the conventional polarizing beam splitter has a Brewster angle of 67.5 °. Incident angle 45 ° Polarizing beam splitter is ø35 mm, which makes it possible to construct an optical path with a larger relaser beam diameter. Here, when a laser beam having a beam diameter D is incident on an f 0 lens having a focal length f and the beam spot diameter collected on the workpiece is d, the beam spot diameter d and the focal point of the f 0 lens The relationship between the distance f and the incident beam diameter D can be expressed by the following equation. d o f ノ D (1)

Equation (1) shows that the beam spot diameter d collected on the workpiece by the f 0 lens with the focal length f is inversely proportional to the beam diameter of the laser light incident on the f 0 lens.

 Therefore, when considering the construction of a polarizing beam splitter with windows of the same diameter, the polarizing beam splitter with an incident angle of 45 ° as described above can secure the effective diameter of the laser beam more effectively, and the same f 0 lens When is used, the beam diameter D incident on the fΘ lens can be increased, which makes it possible to carry out processing with a smaller beam spot diameter. In addition, since a mirror that turns the optical path to 90 ° is not required, the polarization beam splitter is cheaper and the cost of the processing apparatus can be reduced.

In the embodiment of the present invention, the optical path structure in which the laser beam is turned back to 90 °. Therefore, a polarizing beam splitter with an incident angle of 45 ° is used. With this configuration, the scanning direction of the two-axis galvanoscan mirror is orthogonal on the XY table 18, so as shown in Fig. 1, aligning this orthogonal direction with the XY direction allows the X direction and Y Each direction can correspond to the galvano scan mirror on a one-to-one basis, and the control of the galvano scan mirror during machining is easy to understand and a simple configuration can be achieved.

 When the turning angle of the laser beam in the polarizing beam splitter is set to 90 °, the effective diameter of the polarizing beam splitter can be increased and processing with a smaller beam spot diameter can be performed. However, in this case, the scanning direction of the two-axis galvano scan mirror does not go straight on the XY table. For example, even if the scan direction of one galvano scan mirror is aligned with the X direction, the Y direction is the same as the other galvano scan mirror. Since scanning is possible only by combining with the galvano scan mirror in the X direction, the control of the galvano scan mirror during processing is more complicated than the optical path that turns the laser beam back to 90 °. Embodiment 2.

 Since the two laser beams that have been split must pass through the second polarizing beam splitter and be parallel to the axis in the X direction in Fig. 1 and be guided to the center of the second galvano scan mirror 1 2. It is necessary to adjust the optical axes of the laser beams 6 and 7 independently.

In order to accurately guide the laser beams 10 and 1 1 to the second galvanoscan mirror 1 1 2, in the optical path after the mirror 4 z provided immediately before the first polarization beam splitter 5, At least two mirrors that are perpendicular to the direction of travel and can be adjusted in two axes perpendicular to each other are required. However, in the present embodiment, the laser beam 10 can be adjusted in the optical axis by the mirror 4z immediately before the first polarization beam splitter 5 and the second polarization beam splitter 8, while the laser beam 1 The optical axis 1 can be adjusted by the first polarization beam splitter 5 and the first galvano scan mirror 13. Here, the first galvano scan mirror 13 has two mirrors that can be adjusted in the direction of twist with respect to each other, and has the same function as one mirror that can be adjusted in the direction of two axes perpendicular to each other. It can be considered.

 FIG. 2 relates to the second embodiment of the present invention, and is a diagram showing a mechanism capable of adjusting the angle of the polarization beam splitter in two axial directions perpendicular to the traveling direction of the laser light and perpendicular to each other. is there. In FIG. 2, the polarization beam splitter 5 or 8 is supported by a fixed holder 31. The fixed holder 31 is rotatable to the holder 31 via a first rotating shaft 35a. Is supported. In addition, the holder support 32 is supported by the optical base 36 supporting the optical system via a second rotation shaft 35 b perpendicular to the first rotation shaft 35 a. This makes it possible for the polarization beam splitter to adjust the angle in two axial directions perpendicular to the traveling direction of the optical path and orthogonal to each other. In addition, a first adjustment hole 3 4 a that is long in the rotation direction of the fixed holder 3 1 is provided at a joint portion of the holder support 3 2 with the fixed holder 3 1, and the first fixing screw 3 3 a passes therethrough. It is screwed into the fixed holder 3 1, and after the rotation adjustment, the fixed holder 3 1 can be fixed to the holder support 3 2 by tightening the first fixing screw 3 3 a. Similarly, the joint between the holder support 3 2 and the optical base 3 6 can be fixed after rotation adjustment by the second adjustment hole 3 4 b and the second fixing screw 3 3 b.

On the other hand, the change in the optical axis of the laser beam transmitted through the polarizing beam splitter by adjusting the angle of the polarizing beam splitter is extremely small compared to the reflected laser beam and is negligible. By Re-reflected laser light 7, 11 Laser light 6 that is transmitted even if the optical axis of 1 is adjusted, 10 The optical axis of 10 is hardly affected, and the laser light 6 that is reflected by the second polarization beam splitter 8 Adjusting the optical axis of 10 has almost no effect on the optical axis of transmitted laser light 7 and 11 and can be adjusted independently.

In addition, when the angle of the mirror 4 _Z or the first and second polarizing beam splitters 5 and 8 is adjusted, the incident angle to the polarizing beam splitter may deviate from 45 °. Although the loss increases, the angle adjustment is usually small and the energy loss is also small. In addition, correction by the output of the laser oscillator is also possible, so it is desirable to give priority to improving machining accuracy by adjusting the optical axis.

 Next, adjustment of the optical axis by a polarizing beam splitter or the like equipped with the adjustment mechanism will be described.

When the angle adjustment of the mirror 4 z immediately before the first polarization beam splitter 5 is performed, the laser beams 10 and 11 move in the same direction on the second galvano scan mirror 13. Therefore, as the order of the optical axis adjustment direction, first, after the optical axis adjustment of the laser beam 10 using the mirror 4 z acting on the two laser beams is completed, the optical axis adjustment of the laser beam 11 is performed. There is a need. Once the adjustment of the optical axis has been completed, the two lasers on the second galvano-scan mirror 1 2 can be obtained by adjusting the angle of the mirror 4 _Z immediately before the first polarizing beam splitter 5. The optical axes of the laser beams 1 0 and 1 1 can be adjusted while maintaining the relative positional relationship of the light, and the optical axes for accurately guiding the two laser beams to the center of the second galvano scan mirror 1 2 Easy adjustment. Embodiment 3. FIG. 3 relates to the third embodiment of the present invention. By processing one laser beam into two laser beams and scanning the two laser beams independently, processing can be performed at two locations simultaneously. In a drilling laser processing device that can be used, it has an optical system that performs mask transfer, and in particular a mirror that is a set of optical components that have substantially the same surface shape to be placed after the mask. 1 4 b—the beam incident surface of one mirror is perpendicular to the beam incident surface of the other mirror, and the beam incident angle on one mirror is the same as the beam incident angle on the other mirror (for example, 45 °) (for example, a configuration where the laser beam incident from the X direction is reflected in the Z direction by the first mirror and then reflected in the Y direction by the other mirror) FIG. In FIG. 3, 4a and 4b are mirrors having substantially the same surface shape for guiding the laser beam 2 from the mask 3 to the first polarization beam splitter 5, and 14a and 14b are the first polarization. This is a mirror having substantially the same surface shape for guiding from the beam splitter 5 to the second polarizing beam splitter 8.

 The third embodiment is the same as the first embodiment with respect to the polarization beam splitter, but the arrangement or surface shape of the mirror 4. 14 is different. This will be described with reference to the drawings. In Fig. 4, P ru (a) and P rv (Of) are the refractive powers in the u and V directions related to the reflected beam that is incident on the beam incident angle 0; P tu (a) and P tva) are the refractive powers in the u direction and the V direction related to the transmitted beam in which the incident beam incident at the beam incident angle of passes through the mirror. Here, the u direction is perpendicular to the traveling direction of each beam and parallel to the beam incident surface (the surface formed by the incident beam and the reflected beam), and the V direction is perpendicular to the traveling direction of each beam. The direction is perpendicular to the beam entrance plane.

Here, the refractive power (P ower) is a parameter that represents the refracting performance of the optical component. It is one of the lamellae and indicates the state of the refracting surface, and is generally inversely proportional to the surface curvature radius R and proportional to the refractive index n. In Fig. 4, the surface radius of curvature R is concentrically uniform and sufficiently large for the optical system (assuming the surface shape of the optical component is substantially flat), and the refractive index is n. The refractive powers P ru () and P r V () are given by the following equations.

一般的に光学部品は表面形状を平面として製作しても、 製作工程の中 'で僅かに歪みを持ち、 λΖ 1 0〜； Iノ 20程度が一般的な加工精度であ リ、 λΖ20よリ高精度で表面形状を仕上げるためには莫大な時間とコ ス卜を必要とする。 したがって、 一般的な光学部品は； 1 1 0〜； 1 2 0程度の表面曲率半径 Rを持つといえる。 例えば Z n S e ( n = 2. 4 1 ) に誘電体多層膜コーティングを施したビーム入射角 45° の偏光ビ 一ムスプリッタの場合、 (2) (3) 式より、 それぞれ次式が得られる。

In general, even if optical parts are manufactured with a flat surface shape, they are slightly distorted during the manufacturing process. ΛΖ10 ~; I No. 20 is the general processing accuracy, and λΖ20 To finish the surface shape with high accuracy, a huge amount of time and cost are required. Therefore, it can be said that a general optical component has a surface curvature radius R of about 1 1 0 to 1 20. For example, in the case of a polarization beam splitter with a beam incident angle of 45 ° with a dielectric multilayer coating applied to ZnSe (n = 2.4 1), the following equations are obtained from equations (2) and (3), respectively: It is done.

 (45.) = 1.4 X (5) '

(4) As is clear from Eq. (5), at the beam incident angle of 45 °, the refractive power in the u direction is greater than the refractive power in the V direction during reflection. If the difference in refractive power between the u direction and the V direction propagates to the processing point, astigmatism occurs, so it may be difficult to obtain stable processing quality. In contrast, according to the present invention, when constructing an optical system, one set of optical components having substantially the same surface shape among a plurality of optical components is used, and the beam incident surface of one optical component is that of the other optical component. It is arranged so that it is perpendicular to the beam incident surface and the beam incident angle to one optical component is the same as the beam incident angle to the other optical component.

 Here, the configuration will be described using mirrors 1 14 a and 14 b. In Fig. 5, mirror 14a reflects laser light incident from the X direction in the Z direction, and mirror 14b reflects laser light reflected by the mirror 14a in the Y direction. Has been placed. In addition, the mirror surface radius of curvature of the mirror 14 a is R a, and the mirror surface radius of curvature of the mirror 14 b is R b. The power in the u direction of mirror 14 a is P aru (45 °), the power in the v direction is P arv (45 °), and the power in the u direction of mirror 14 b is P bru (45 °), Assuming that the refractive power in the v direction is P brv (45 °), the combined refractive power P ru of the laser beam reflected by the mirror 14 b and the mirror 14 b of the laser beam 14 b and the mirror 14 b b in the V direction The refractive power P r V is as follows.

P _m = Ρ _α , (45 °) + P _bnt (45 °) = 1.4 x ^ + 2.8 x (6)

P. = Ρ _αηι (45 °) + P _bn , (45 °) = 2,8 x ^ + 1.4 x-(7)

Here, since mirrors 14 a and 14 b have substantially the same surface shape, R a = R b and P ru and P rv are not substantially equal, so that the refractive power in the u and V directions As a result, the astigmatism difference at the machining point can be reduced and stable machining quality can be obtained. Since Mira_4a and Miller 4b have the same structure, the same effect can be obtained. The above was examined at = 45 °, but at a general angle, -^ (Hi) + (a) = 2co _S hi R _n + —— cos R _b "( ⁸ )

P _n , = (+ (= — cos ― R _a + ^{2cos a} ~ (9)

When R _b R a = R b, 明 ら か 卩 ri and r V are approximately equal, as is clear from Eqs. (8) and (9), this cancels the difference in refractive power between u and V directions. As in the case of = 45 °, astigmatism at the machining point can be reduced, and stable machining quality can be obtained.

 By the way, if the holder member that fixes the optical component has a directional structure, the surface curvature radius of the mirror supported by this holder changes along the directionality and astigmatism occurs. The mirrors supported by one set of the holders are aligned in the same direction with respect to each incident surface, and the beam incident surface of one optical component is incident on the beam of the other optical component. It is arranged so that it is perpendicular to the surface and the beam incident angle to one optical component is the same as the beam incident angle to the other optical component.

 Figure 6 shows an example. In FIG. 6, the first optical component 3 7a and the second optical component 3 7b are optical components having the same surface shape, and the first holder member 3 8a and the second holder one member 3 8b have the same shape. This is an optical component fixing member. A and B indicate the directional axes of each holder member. When an optical component such as a mirror is attached to this holder, the radius of curvature of the mirror surface is RA in the A direction and RB in the B direction.

As shown in FIG. 6, the first optical component 3 7 a and the second optical component 3 7 b are connected to the first optical component 3 7 a. The beam incident surface of the first optical component 3 7 a is the beam of the second optical component 3 7 b. The beam incidence angle to the first optical component 37a is When the second optical component 3 7 b is placed so that it is the same as the beam incident angle (for example, 45 °), and the direction A is parallel to the incident surface to match the direction of the holder member, the second The bending forces P ru and P rv in the u and V directions when the optical component 3 7 b is reflected are as follows.

Ρ _ηι = Ρ, _α (45 °) + Ρ _ηΛ (45 °) = 1.4 x ^ + 2.8 x-(10)-Ρη = (45 °) + (45 °) = 2.8 χ-^-+ 1.4 χ ^ -(11)

As is clear from (1 0) and (1 1), Ρ ru and Ρ r ν are equal, and the point aberration due to the directional holder can be canceled. As a result, astigmatism at the machining point can be reduced, and stable machining quality can be obtained. As described above, it is clear that astigmatism can be canceled even when the incident angle is other than 45 °.

 In addition, an inexpensive holder member having directionality can be used, and the cost of the processing apparatus is reduced.

 In the present embodiment, in the optical system for performing mask transfer, a plurality of optical components arranged after masking have been described. This is because, in mask transfer, aberrations of the optical components after the mask affect the beam quality at the processing point. Furthermore, it goes without saying that more effective results can be obtained by arranging a plurality of optical parts before the mask in the same way.

In addition to the optical system that performs mask transfer, the optical aberration can be reduced by arranging optical components in the same way. Embodiment 4. 2 FIG. 5 relates to Embodiment 4 of the present invention. As a first polarization separation means, a polarization beam splitter having a convex shape on the front surface and a concave shape on the back surface, and as a second polarization separation means, Using a polarized beam splitter with a concave surface and a convex back surface, one laser beam is split into two laser beams, and the two laser beams are scanned independently, thereby simultaneously processing two locations. FIG. 3 is a configuration diagram showing a laser processing apparatus for drilling that can be performed.

 In Fig. 7, 2 2 is a polarizing beam splitter with a convex shape on the front side and a concave shape on the back side (see Fig. 8 (a)). 1 splitter (see Fig. 8 (b)). Here, each surface shape is determined by the shape of the polishing machine that is the production machine, so by controlling the production method, either the concave shape or the convex shape can be selected with the flatness of the desired processing accuracy. Can be produced.

 The fourth embodiment is different from the first embodiment in the configuration of the surface shape of the polarizing beam splitter, and the shape of the polarizing beam splitter, which is a feature of the present invention, will be described.

 In Fig. 4, P tu () and P t V (Of) are the refractive powers in the u and V directions of the transmitted beam through which the incident beam incident at the beam incident angle passes through the optical component. If the radius R is concentrically uniform and sufficiently large for the optical system (assuming that the surface shape of the optical component is a substantially flat surface), and the refractive index is n, the refractive power P tu (a) P t V (Of) is given by

例えば Z n S e ( n = 2. 4 1 ) に誘電体多層膜コーティングを施し たビーム入射角 4 5° の偏光ビームスプリッタの場合、 （ 1 2) ( 1 3 ) 式より、 それぞれ次式が得られる。

For example, in the case of a polarizing beam splitter with a beam incident angle of 45 ° with a dielectric multilayer coating on ZnSe (n = 2.4 1), the following equations are obtained from (1 2) and (1 3), respectively. can get.

^, (45 °) = 3.2x- (14) ^ _v (45 ⁰ ) = 1.6x ^ (15)

(4) (5) (1 4) (1 5) As is clear from the equation, at the beam incident angle of 45 °, the refractive power in the u direction is larger than the refractive power in the V direction not only during reflection but also during transmission. . If this difference in refractive power between the u direction and the V direction propagates to the processing point, astigmatism occurs, and it may be difficult to obtain stable processing quality.

 Here, attention is paid to the refractive power during transmission of the polarizing beam splitter. In addition to the refractive power at the surface of the polarizing beam splitter, the refractive power at the back is added. In other words, the refractive powers P tua (45 °) and P tva (45 °) in the u direction and direction during transmission are expressed as 1 and 2 on the front and back sides, respectively, from the equations (14) and (15). The following is shown as a subscript.

1 1

^ (45 °) = _ia „ ₁ + ^ _H2 = 3.2x — + — (16) (45 °) (17)

したがって、 第 8図 （a) に示すように表面が凸形状 （R 1 > 0) 、 裏面が凹形状 （R 2 < 0) であると、 表面と裏面の屈折力が打ち消すた め、 透過時の屈折力は小さくなる。 結果として、 u方向と V方向の屈折 力の差が小さくなるので、 非点収差を低減する効果がある。

Therefore, as shown in Fig. 8 (a), if the surface has a convex shape (R 1> 0) and the back surface has a concave shape (R 2 <0), the refractive power of the front and back surfaces will cancel out. The refractive power of becomes small. As a result, refraction in u and V directions Since the difference in force is small, there is an effect of reducing astigmatism.

 Also, when the front surface is concave (R 1 0) and the back surface is convex (R 2> 0) as shown in Fig. 8 (b), the refractive power of the front and back surfaces cancels out. The refractive power at the time is small, and as a result, the difference between the bending forces in the u direction and the V direction is small, which has the effect of reducing astigmatism.

 Since the surface shape of the polarizing beam splitter in this invention needs to have the same absolute value of the radius of curvature of the front surface and the back surface, it is desirable to improve the processing accuracy as usual, and i Z 20 or less is desirable. .

 Next, the optimum shape of the first polarizing beam splitter and the second polarizing beam splitter in the entire optical system will be described.

 As in the previous discussion of refractive power, the refractive power of individual optical components is also added to the entire optical system, and as a result, it is determined whether the aberration is large or small. Therefore, for the optical component between the first polarizing beam splitter 22 and the second polarizing beam splitter 23 used in the optical system of FIG. The explanation is divided into the optical path A of 6 and the optical path B of the reflected laser beam 7.

 In the optical path A, the laser beam 6 transmitted through the first polarization beam splitter 22 is guided to the second polarization beam splitter 23 by the mirrors 14 a and 14 b. Since the mirrors 14a and 14b are relatively easy to manufacture, the accuracy of the flatness to be finished can be as high as 1/10 ~; IZ20. However, as shown below, the flatness of the galvanoscan mirror tends to be relatively poor, so it is desirable to finish it with a precision of about 15-15; I20.

On the other hand, in the optical path B, the laser beam 7 reflected from the first polarization beam splitter 22 is positioned by the first galvano scan mirrors 13 a and 13 b, and the second polarization beam Guided to splitter 2 3. First gal Banoscan mirrors 1 3 a and 1 3 b need to be very light to move at high speed, and the area is large to prevent degradation of machining quality as explained in equation (1). Therefore, it is very difficult to manufacture because it has a thin and wide shape, and the flatness to be finished tends to be poor compared to the above mirrors, about λ Ζ, 1 0 to Λ Ζ 15 It is. In addition, the surface shape is more strongly dependent on the production machine, for example, a strong concave shape.

 If the flatness differs between the optical path Α and the optical path Β, there may be a difference in the added refractive power. This difference in refractive power may be a focal difference between optical path A and optical path B.

 In this invention, when the surface shape of the first galvano scan mirrors 1 3 a and 1 3 b is a strong concave shape, the surface shape of the first polarizing beam splitter 2 2 is a convex shape, and the back surface shape is a concave shape. The surface of the second polarizing beam splitter 2 3 is concave, and the back is convex.

 With this configuration, almost no refractive power is generated in the optical path A during transmission through the first polarization beam splitter 22, and the mirrors 14 a and 14 b have a slight surface shape. It has a refractive power slightly in the convergence direction from the concave shape, and is guided to the second polarization beam splitter 2 3, and when reflected by the second polarization beam splitter 2 3, it is refracted in the convergence direction from the slight concave shape of the surface shape. The power is added. As a result, the laser light has a refractive power slightly in the convergence direction.

On the other hand, in the optical path B, the first galvanometer scan mirror 1 3 a, 1 3 b has a refractive power slightly in the direction of divergence from the convex shape of the surface when reflected by the first polarizing beam splitter 22. Led to. Since the first galvanoscan mirrors 1 3 a and 1 3 b have a strong concave shape, the strong power in the converging direction is added. Are transmitted through the polarizing beam splitters 2 and 3 with substantially the same refractive power.

 In the above, the surface shapes of the mirrors 14 a and 14 b are slightly concave, but even in the case of a slight convex shape, the surface shapes of the first galvano scan mirrors 13 a and 13 b are strongly concave. The first polarization beam splitter 2 2 has a convex shape, the back surface shape has a concave shape, the second polarization beam splitter 2 3 has a concave shape, and the back surface shape has a convex shape. By doing so, the difference in refractive power between optical path A and optical path B can be reduced. However, the concave shape is desirable because the surface shape of the mirrors 14 a and 14 b is reduced slightly when the surface shape is slightly concave.

 As described above, according to the present invention, the aberration component of each optical component is canceled in the optical system, and as a result, an optical system with less optical aberrations such as astigmatism and focal difference is obtained. effective.

 Further, in the present embodiment, the first polarization separation means is a polarization beam splitter having a convex surface and the back surface is concave, and the second polarization separation means is a concave surface and the back surface is convex. If the first galvano scan mirrors 1 3 a and 1 3 b have a strong convex shape, the polarizing beam splitter has a concave shape on the front surface and a convex shape on the back surface. If the splitter and the polarization polarization splitter with the convex surface on the front side and concave shape on the back surface are used as the second polarization separation means, the aberration components of the individual optical components are contained in the optical system. Can be canceled. As is clear from the above description, it goes without saying that the optimum values of the shape and flatness differ depending on the optical system or optical parts used in the optical system.

In the present embodiment, attention has been paid to the shapes of the first and second polarization separation means. However, as is clear from the above description, the optimum value can be obtained by the same way of thinking in other optical components. Needless to say. Further, although the embodiments have been described separately as 1, 2, and 3, it goes without saying that these can be combined. Industrial applicability

 The laser processing apparatus according to the present invention splits one laser beam into two or more laser beams, and simultaneously reduces the manufacturing difficulty and cost in the case of performing laser processing at two or more locations. Suitable for improving processing quality.

Claims

The scope of the claims 1. It has an optical system composed of a plurality of optical components that guides the laser beam emitted from the laser oscillator to the workpiece. 5 splits the light into two laser beams, one passes through the mirror, the other scans in the biaxial direction with the first galvano scan mirror, and the two laser beams are guided to the second polarization 'separation means. Later, in a laser processing device that scans with a second galvano scan mirror and processes the workpiece,  The first and second polarization separation means are 45 ° to the optical axis of the laser beam. 10 is a laser processing apparatus. 2. The laser processing apparatus according to claim 1, wherein the first and second polarization separation means are polarization beam splitters each having a dielectric multilayer coating formed on a surface thereof.  15  3. The laser processing apparatus according to claim 1, wherein the first and second polarization separation means have a concave shape on one side and a convex shape on the back side. 20 4. The first polarized light separating means has a convex surface on the side that reflects the laser light, and a concave surface on the back surface.  The laser beam reflected by the first polarization separation means is guided to the first galvano scan mirror whose surface shape is a concave shape, 4. The laser processing apparatus according to claim 3, wherein the second polarized light separating means has a concave surface on the side that reflects the laser light and a convex surface on the back surface thereof. 5. The first polarized light separating means has a concave surface on the side that reflects the laser light and a convex surface on the back surface.  The laser beam reflected by the first polarization separation means is guided to the first galvano scan mirror having a convex surface shape,  4. The laser processing apparatus according to claim 3, wherein the second polarized light separating means has a convex shape on the surface that reflects the laser light and a concave shape on the back surface. 6. The concave or convex shapes of the surfaces of the first and second polarization separation means are formed with an accuracy of λ 20 or less when the wavelength of the laser beam is λ. The laser processing apparatus according to any one of ranges 3 to 5. 7. In the optical system, a set of optical components having substantially the same surface shape is formed by using a beam incident surface of one optical component perpendicular to the beam incident surface of the other optical component and a beam to one optical component. 7. The laser processing apparatus according to claim 1, wherein the laser processing apparatus is arranged so that the incident angle is the same as the beam incident angle to the other optical component. 8. A mask is provided in the laser beam path from the laser beam emitted from the laser oscillator to the first polarized light separating means,  8. The laser processing apparatus according to claim 7, wherein the one set of optical components is disposed between the mask and the workpiece. 9. Having a holder for individually fixing the set of optical components, 8. The laser processing apparatus according to claim 7, wherein when the holder has directionality, the direction is arranged in the same direction with respect to an incident surface of each optical component. 10. The surface shape of the one set of optical components is formed with an accuracy of λ / Λ 0 to IZ 20 when the wavelength of the laser light is taken. 9. The laser processing apparatus according to any one of 8. 11. The first and second polarization separation means are provided with a mechanism capable of adjusting an angle in two axial directions perpendicular to a traveling direction of laser light and orthogonal to each other. The laser processing apparatus according to range 1. 1. The laser processing apparatus according to claim 1, further comprising a damper for absorbing laser light leaking as energy loss from the second polarization separation means.