JPH11163442A - Laser beam machine and method for fixing laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mis-alignment of the optical system of a laser generator due to the laser generator being fixed to the pedestal of a laser system. SOLUTION: A laser beam body is provided with a laser oscillator 1, in which a fundamental wave oscillating section containing a YAG crystal and a wavelength converting crystal which converts the wavelength of the fundamental wave outputted from the fundamental wave oscillating section into higher harmonics, a pedestal 14 on which an optical system which introduces laser light outputted from the laser oscillator 1 to a laser beam machining section and a base plate 6 of the oscillator 1 are fixed, a warpage compensating member 30 which is less rigid than the base plate 6 and the pedestal 14, provided between the base plate 6 and pedestal 14, and compensates for the warpage of the base plate 6 from the pedestal 14, and at least three screw sections 31 which fix the base plate 6 to the pedestal 14 via the compensating member 30 to such an extent that the base plate 6 is not strained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fundamental wave oscillating unit,
A laser processing machine in which a YAG laser oscillator having a wavelength conversion crystal such as an SHG crystal or a THG crystal, a reflecting mirror, etc. mounted on a base plate is installed on a base, and such a YAG laser oscillator is mounted on a laser system base. Regarding the fixing method.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Application Publication No.
There is known a laser system which can remove a thin film or the like of an IC using an excimer laser and can observe the inside of the IC, as described in Japanese Patent Application Laid-Open No. 14-214, 1988. However, the excimer laser has a drawback in that it is difficult to handle the excimer laser because a rare gas and a halogen gas or the like must be flown while being mixed and oscillated by high-pressure pulse discharge. Therefore, the present inventor has proposed a YAG that generates harmonics instead of an excimer laser.
An attempt was made to use a laser.

[0003]

However, a YAG laser generator for generating a harmonic wave whose alignment of an optical system such as a wavelength conversion crystal and a reflecting mirror has been accurately adjusted is preliminarily adjusted to a laser system. When it was used by incorporating it into a, a situation occurred in which the harmonic output was reduced. That is, since the output of the harmonic wave is remarkably reduced when the angle of the light incident on the wavelength conversion crystal is slightly deviated, the Y is accurate before being fixed to the base of the laser system.
The alignment of the optical system of the AG laser generator has gone out of order due to some influence.

Accordingly, the present invention has been made to solve such a conventional problem, and it has been proposed that the alignment of an optical system of a laser generator be disordered by fixing the laser generator to a base of a laser system. The purpose is to prevent it.

[0005]

Means for Solving the Problems The present inventor has repeated trial and error in order to solve the above-mentioned problems, and as a result of pursuing the cause of the misalignment of the optical system of the laser generator, found a certain probable cause. It is as follows. Normally, even if the alignment of the optical system of the YAG laser generator or the laser system is accurate, the base substrate on which the optical components such as the fundamental wave oscillating unit and the SHG crystal of the YAG laser generator are mounted is not necessarily flat. It is often warped and distorted.

For this reason, when the YAG laser generator is directly placed on the metal flat base of the laser system and fixed with several screws, the base substrate of the YAG laser generator is turned on by the fastening force of the screws. It is distorted and deformed to fill the gap with the base. The amount of deformation of this base substrate is as small as the amount of warpage before fixing the base substrate, but the optical system of a YAG laser generator or laser system for the purpose of ultra-fine processing such as removal of a thin film of an IC. Is enough to upset the alignment.

That is, when the YAG laser generator is fixed to the laser system, distortion occurs in the base substrate. As a result, it is considered that the alignment of the optical system is out of order and the harmonic output is reduced.

In order to prevent the occurrence of distortion in the base plate or the base, it is conceivable to dispose the YAG laser generator without fixing it to the laser system. However, this method has poor earthquake resistance and causes laser oscillation. It cannot be performed stably.

[0009] Therefore, the present inventor fixed both of the YAG laser generator and the laser system with a metal ring interposed between them. However, in this case, if the screws are tightened tightly, distortion will occur in the base board, lowering the harmonic output,
Conversely, if the screws were loosely tightened, the earthquake resistance was weak, and laser oscillation could not be performed stably.

Therefore, it is possible to prevent misalignment of the alignment of the laser generator and the optical system of the laser system due to distortion of the base substrate or the base of the laser generator which occurs when the laser generator is fixed to the base of the laser system. In order to perform laser oscillation in a state in which the fundamental wave is oscillated, the laser processing machine of the present invention is based on a fundamental wave oscillating unit including a YAG crystal and a wavelength conversion crystal that converts the wavelength of the fundamental wave output from the fundamental wave oscillating unit into a harmonic. A laser oscillator mounted on a plate, an optical system for guiding laser light output from the laser oscillator to a laser processing unit, a base on which a base plate of the laser oscillator is fixed, a base plate and a base Less rigid than, provided between the base plate and the base, a warp compensating member for compensating for the warpage of the base plate with respect to the base, via the warp compensating member,
At least three screw portions for fastening the base plate and the base to such an extent that the base plate is not distorted are provided.

According to this laser processing machine, even when the optical system alignment of the laser oscillator is adjusted in a state where the base plate on which the fundamental wave oscillator and the wavelength conversion crystal are mounted is warped, the distance between the base plate and the base can be improved. In addition, since the warp compensating member having lower rigidity than the base plate and the base is interposed, the laser oscillator can be fixed to the base in a stable state while maintaining the warp of the base plate. Therefore, the laser processing can be accurately performed without the optical system alignment of the laser oscillator being out of order. Furthermore, since the laser oscillator and the base are fastened by at least three screw members, the laser oscillator can perform laser oscillation in a more stable state.

Preferably, the warp compensating member covers the entire lower surface of the base plate. If this laser processing machine is used, the warp compensating member can support the laser oscillation section over a wide area, so that laser oscillation can be performed in a stable state.

Preferably, the warp compensating member is a ring-shaped member, and the same number of ring-shaped members as the number of screw portions are provided between the base plate and the base. If this laser processing machine is used, since the ring-shaped member is used as the warp compensating member, it is possible to easily prevent the alignment of the optical system from being disordered. Therefore, laser oscillation can be stably performed.

[0014] It is preferable that the same number of pillars having screw portions at both ends are provided between the warp compensating member and the base. With this laser beam machine, the height of the laser oscillator with respect to the base can be freely set by the support, and the positioning can be easily performed.

Preferably, the warp compensating member is made of plastic. If this laser processing machine is used, the rigidity is low with respect to the laser oscillator and the base, which are often made of metal, so that warpage can be easily compensated.

Further, in the method for fixing a laser oscillator according to the present invention, a fundamental wave oscillating section including a YAG crystal and a wavelength conversion crystal for converting a wavelength of a fundamental wave output from the fundamental wave oscillating section into a harmonic are used as base plates. A base plate and a base between the base plate of the laser oscillator mounted thereon and an optical system for guiding laser light output from the laser oscillator to a laser processing unit and a base on which the base plate is fixed. A first step of providing a warp compensating member for compensating for the warpage of the base plate with respect to the base, and a degree that the base plate is not distorted through the warp compensating member. And a second step of fixing with at least three screw portions.

According to this method of fixing the laser oscillator, even when the optical system alignment of the laser oscillator is aligned in a state where the base plate on which the fundamental wave oscillator and the wavelength conversion crystal are mounted is warped, the base plate and the base plate can be fixed. Since the warp compensating member having lower rigidity than the base plate and the base is interposed between the bases, the laser oscillator can be fixed to the base in a stable state while maintaining the warp of the base plate. . Therefore, the laser processing can be accurately performed without the optical system alignment of the laser oscillator being out of order. Further, since the laser oscillator and the base are fastened by at least three screw members, the laser oscillator can be fixed to the base in a more stable state.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a laser beam machine and a method for fixing a laser oscillator according to the present invention will be described below in detail.

FIG. 1 is an internal plan view of a YAG laser oscillator 1 used in a first embodiment of the laser beam machine according to the present invention. The YAG laser oscillator 1 includes a fundamental wave oscillating unit 2 for generating a fundamental wave and an SHG (Seco) for generating a second harmonic.
and a dichroic mirror 5 for reflecting light of a specific wavelength on a metal base plate 6. SHG3 and THG4 are stored in a sealed case because they are weak to humidity. Further, the SHG 3 and THG 4 are provided with a crystal angle adjusting unit (not shown) that can adjust the direction of each crystal in order to obtain the maximum output of the laser.

An SHG 3 and a THG 4 are provided on the optical path of the laser emitted from the fundamental wave oscillating unit 2. Further, the optical path has an inclination of 45 ° with respect to the optical path, and the first
Is arranged, and a second dichroic mirror 5b is arranged in parallel with the first dichroic mirror 5a.

FIG. 2 is a perspective view of the YAG laser oscillator 1 used in the present embodiment. The housing 7 is provided with an optical window 8 for transmitting laser light from the inside.

FIG. 3 shows a YAG configured as described above.
1 is a system configuration diagram of a laser processing machine 10 to which a laser oscillator 1 is attached. This laser processing machine 10 is mainly used for IC
Used to remove the thin film. Note that, for convenience of description, various power supplies, power supply control units, and the like are omitted. The laser beam machine 10 is completed by attaching the YAG laser oscillator 1 to the laser system 11.

First, the configuration of the laser system 11 will be described. The laser system 11 is roughly divided into two parts, a processing part 11a for removing a thin film of an IC and a processing part 1 for removing the thin film.
The power supply unit 11b has a role of supporting the power supply unit 1a. A laser power supply 13 for supplying power to the YAG laser oscillator 1 is housed in the power supply section 11b.

At the bottom of the processing portion 11a, a metal vibration isolator 14a functioning as a base is provided, and together with the housing cover 14b, forms an airtight container for shielding external light. A first mirror 15 on which the optical path A of the laser light emitted from the YAG laser oscillating body 1 to be attached later is bent upward by 90 ° to form an optical path B, and a workpiece to be processed. A stage section 17 for moving and fixing the IC 16 to a desired position is provided. The stage unit 17 includes an XY stage 17a and a Z stage 1.
7b.

On the optical path B above the first mirror 15,
A beam shaping optical system 18 for expanding the diameter of the laser light, a variable attenuator 19 for reducing the intensity of the laser light, and an optical path B
And a second mirror 20 having an optical path B as an optical path C and an inclination of 45 ° with respect to the second mirror 20 is provided. This second mirror 2
On the side of 0, a mask illumination 20a for observing where on the IC 16 the laser light is irradiated is arranged. On the optical path C, there is a variable slit 21 for narrowing the laser light into a desired shape, and the optical path C has an inclination of 45 ° with respect to the optical path C,
A third mirror 22 is provided that makes the optical path C an optical path D toward the stage section 17. On the optical path D, a reduction projection lens 23 for reducing the laser beam diameter is provided. On the side of the reduction projection lens 23, an observation lens 24 used for observing the IC 16 as a workpiece with the naked eye is disposed.

Above the third mirror 22, via a fourth mirror 25 for observing the IC 16 with the CCD camera 26, a CCD camera 26 for imaging the state of the surface of the IC 16 and a monitor 27 are arranged. ing. Also, the fourth
Aside from the mirror 25, an observation illumination 25a for illuminating the fourth mirror 25 to observe the IC 16 with the CCD 26 is provided.
Is arranged.

Next, a method of attaching the YAG laser oscillator 1 to the laser system 11 will be described with reference to FIG. FIG. 4A shows that the vibration isolation table 14 of the laser system 11 has YA.
FIG. 2 is a perspective view showing a state in which a G laser oscillator 1 is fixed.
FIG. 4B is a side view showing a process of attaching the YAG laser oscillator 1 to the vibration isolation table 14. Screw holes 28 are provided at four corners of the base plate 6 having minute warpage, and four screw holes 29 are formed in the vibration isolation table 14. And
Four 1 mm-thick plastic ring members 30 are interposed between the base plate 6 and the vibration isolation table 14, and the base plate 6 and the vibration isolation table 14 are fastened by screws 31.

FIG. 5 is a side view showing the state of the ring member 30 and the base plate 6 before and after the fastening of the base plate 6 and the vibration isolation table 14. In addition, for the sake of convenience of understanding, the amount of warpage of the base plate 6 and the thickness of the ring members 30a and 30b are exaggerated. As shown in FIG. 5A, it is assumed that the base plate 6 is warped by a small angle α. Then, the screw 31 has a fastening force that does not change the warp angle α of the base plate 6, that is, the screw 31 is capable of accurately performing laser oscillation without disturbing the optical system alignment of the YAG laser oscillator 1 and the laser system 11.
, The base plate 6 is fixed to the vibration isolation table 14. Than the metal base plate 6 and the vibration isolation table 14,
Since the plastic ring members 30 a and 30 b have lower rigidity, the ring members 3
0a and 30b are deformed. Moreover, the metal base plate 6
The YAG laser oscillator 1 can be attached to the laser system 11 with a larger fastening force than when a ring member having the same rigidity as that of the vibration isolator 14 is used.

As shown in FIG. 5, when the interval between the base plate 6 near the right ring member 30a and the vibration isolation table 14 is smaller than the interval near the left ring member 30b, the ring member 30 is used.
The ring member 30a is crushed more than b, and the warpage of the base plate 6 can be maintained. Therefore, the YAG laser oscillator 1 can be attached to the laser system 11 without distorting the base plate 6 and the vibration isolation table 14, that is, without disturbing the optical system alignment of the YAG laser oscillator 1 and the laser system 11. it can. If Y
If the output decreases after the AG laser oscillator 1 is attached, it can be dealt with by adjusting the amount of tightening of the screw 30 again. The YAG laser oscillator 1 is fixed to the laser system 11 so that the optical path A of the laser emitted from the optical window 8 of the YAG laser oscillator 1 passes through the center of the first mirror 15 of the laser system 11. .

The arrangement of the screws 30 and the screw holes 28 for fixing the YAG laser oscillator 1 to the laser system 11 is not limited to that of the present embodiment. For example,
A screw hole 28 is provided in the vibration isolation table 14, and a screw 31 is inserted from above the base plate 6 for fastening, or a screw is provided on the lower surface of the base plate 6, and fastening can be performed using a nut below the vibration isolation table 14. . Furthermore, a screw is provided on the upper surface of the vibration isolation table 14,
It can also be fastened by a nut above the base plate 6.

Next, referring to FIG. 1 and FIG.
The laser oscillation process by the G laser oscillator 1 will be described. First, when a voltage is supplied from the laser power supply 13 to the YAG laser oscillator 1, the fundamental wave oscillator 2 made of a crystal in which Y ₃ Al ₅ O ₁₂ is doped with Nd as an impurity has a wavelength of 1064 nm.
Is generated. Subsequently, the second harmonic of 532 nm and the third harmonic of 355 nm are sequentially generated by SHG3 and THG4.
Harmonics are generated. Then, the third dichroic mirror 5a that reflects light of the wavelength of the third harmonic,
The optical path of the harmonic laser light is bent by 90 °, and further bent by 90 ° toward the optical window 8 by the second dichroic mirror 5b.
Fired at 5. As described above, since the YAG laser oscillator 1 is fixed to the laser system 11 so that the optical system alignment is not deviated, it is possible to emit laser light having a desired output.

As shown in FIG. 6, a reflecting mirror 9a and a reflecting mirror 9b that bend the optical path of the laser light emitted from the fundamental wave oscillating section 90 by 90 ° are provided so as to face each other, so that the YAG laser oscillator 1 is provided. Can be shortened in the longitudinal direction. Further, instead of THG4 that generates the third harmonic, FHG that generates the fourth harmonic (266 nm) is used.
(Forth Harmonic Generators) 32 can also be used.

As shown in FIG. 3, the laser light emitted from the optical window 8 is bent upward by 90 ° by the first mirror 15 and travels on the optical path B. Then, the diameter of the laser light is expanded by the beam shaping optical system 18 and the variable attenuator 1
The intensity is reduced by 9 and reaches the second mirror 20. The laser light that has reached the second mirror 20 is bent by 90 ° and travels on the optical path C. And the variable slit 21
Then, the light is reduced to a desired shape, and reaches the third mirror 22. The laser light that has reached the third mirror 22 is bent by 90 ° and travels on the optical path D. And a reduction projection lens 2
By 3, it is reduced to reach the IC 16 while maintaining the shape formed by the variable slit 21, and the thin film of the IC 16 is removed. The state of the surface of the IC 16 is imaged by the CCD camera 26, and the imaged result is displayed on the monitor 27. Further, the IC 16 can be observed by the observation lens 24.

Next, a second embodiment of the present invention will be described with reference to FIG. In the laser beam machine of the present embodiment, four columns 33 for supporting the YAG laser oscillator 1 are interposed between the ring member 30 and the vibration isolation table 14a. Post 3
The height of the YAG laser oscillator 1 can be adjusted by changing the length of the YAG laser oscillator 3, which is effective when the first mirror 15 is arranged at a higher position with respect to the anti-vibration table 14 shown in FIG. is there. 7B, a screw 33a is provided at the upper end, and a screw hole 33b is provided at the lower end.
On the contrary, a screw hole may be formed at the upper end and a screw may be provided at the lower end. Furthermore, it is also possible to provide a screw at both ends or to form a screw hole at both ends. Further, instead of directly disposing the column 33 on the vibration isolation table 14a, a fixed table for supporting the column 33 may be provided between the column 33 and the vibration isolation table 14a.

Next, a third embodiment according to the present invention will be described with reference to FIG. The laser beam machine according to the present embodiment has a thickness of 1 m as a warp compensation member instead of the ring member 30.
m, the area of the surface in contact with the base member 6 is
A plastic thin plate 34 having the same area as that of the lower surface is used. In this case, the thin plate 34 is the YAG laser oscillator 1
Can be supported over a wide area, so that laser oscillation can be performed in a stable state.

[0036]

As described above, according to the laser beam machine and the method for fixing the laser oscillator of the present invention, even when the optical system alignment of the laser oscillator is aligned in a state where the base plate is warped, the base machine can be used. Since a warp compensating member having lower rigidity than the base plate and the base is interposed between the plate and the base, the laser oscillator is fixed to the base in a stable state while maintaining the warp of the base plate. be able to. Therefore, the laser processing can be accurately performed without the optical system alignment of the laser oscillator being out of order. Furthermore, since the laser oscillator and the base are fastened by at least three screw members, the laser oscillator can perform laser oscillation in a more stable state.

[Brief description of the drawings]

FIG. 1 is an internal plan view of a YAG laser oscillator used in a first embodiment of a laser beam machine according to the present invention.

FIG. 2 is a perspective view of a YAG laser oscillator used in the first embodiment of the laser beam machine according to the present invention.

FIG. 3 is a system configuration diagram showing a first embodiment of the laser beam machine according to the present invention.

FIG. 4 is a view used to explain a method of attaching a YAG laser oscillator to a laser system.

FIG. 5 is a diagram showing a state of a ring member and a base plate before and after fastening of the base plate and the vibration isolation table.

FIG. 6 is a diagram showing a modification of the YAG laser oscillator.

FIG. 7 is a view showing a second embodiment of the laser beam machine according to the present invention.

FIG. 8 is a view showing a third embodiment of the laser beam machine according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... YAG laser oscillator, 2 ... fundamental wave oscillation part, 6 ... base plate, 10 ... laser processing machine, 11 ... laser system, 1
4a: anti-vibration table, 16: IC, 30a: ring member, 30
b: ring member, 31: screw, 33: support, 34: thin plate.

Claims (6)

[Claims] A laser oscillator having a fundamental wave oscillating section including a YAG crystal and a wavelength conversion crystal for converting a wavelength of a fundamental wave output from the fundamental wave oscillating section into a harmonic, mounted on a base plate; An optical system that guides laser light output from the laser oscillator to a laser processing unit, a base on which the base plate of the laser oscillator is fixed, and a lower rigidity than the base plate and the base, A warp compensating member provided between the base plate and the base, for compensating a warp of the base plate with respect to the base; and the base plate and the base via the warp compensating member. A laser processing machine comprising: at least three screw portions that are fastened to such an extent that the base plate is not distorted. 2. The laser beam machine according to claim 1, wherein the warp compensating member covers the entire lower surface of the base plate. 3. The warp compensating member is a ring-shaped member, and the number of the ring-shaped members provided between the base plate and the base is the same as the number of the screw portions. The laser processing machine as described. 4. Between the warp compensating member and the base,
The laser processing machine according to any one of claims 1 to 3, wherein the same number of columns having screw portions at both ends as the number of the screw portions are provided. 5. The laser beam machine according to claim 1, wherein the warp compensating member is made of plastic. 6. A laser oscillator according to claim 1, wherein a fundamental wave oscillating section including a YAG crystal and a wavelength conversion crystal for converting a wavelength of a fundamental wave output from said fundamental wave oscillating section into a harmonic are mounted on a base plate. A base plate, between an optical system that guides laser light output from the laser oscillator to a laser processing unit and a base on which the base plate is fixed, has lower rigidity than the base plate and the base. A first step of providing a warp compensating member for compensating a warp of the base plate with respect to the base; and the base plate is not distorted through the warp compensating member. A second step of fixing with at least three screw portions to a degree.