JPH04167991A - Beam condensing device and laser beam trimmer device - Google Patents

Abstract

PURPOSE:To obtain a laser trimmer device, which can adjust precise resistance, by further dispersing a dispersing layer beam injected from injecting end of optical fiber and condensing this laser beam. CONSTITUTION:By condensing the laser beam Li introduced from the laser beam apparatus with the optical fiber 6 and injected from the injecting end of optical fiber 6, this irradiates onto an objective material. Then, the dispersing laser beam Li injected from the injecting end of optical fiber 6 is further dispersed with a first and second lens groups 1, 2 in dispersing lens system. This dispersed laser beam is condensed to a beam condensed point P as a focusing beam Lr with a third, fourth and fifth lens groups 3, 4, 5 in focusing lens system. By this method, while holding the beam condensed spot diameter to sufficiently small, the distance between the injecting end of laser beam and the material to be machined is secured by the necessary distance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a condensing device that condenses laser light emitted from an output end of an optical fiber, and a laser trimmer device using this condensing device.

[Prior Art] For example, in the field of laser processing, particularly in the field of laser trimming and laser repair, after a laser beam is guided from a laser device to a desired site by an optical fiber, the light emitted from the output end of the optical fiber is used. A method that focuses the light on the object to be processed is attracting attention.

Here, laser trimming refers to focusing a laser beam on a resistive film formed on an IC circuit or the like, and heating and removing a part of the resistive film to adjust the resistance value to a desired value. Furthermore, laser repair refers to focusing a laser beam on a defective portion of a mask pattern for IC manufacturing, etc., and removing the defective portion by heating.

Conventionally, a long working distance microscope has been used as a condensing optical system for these devices, and this has been directly connected to a laser device. However, due to the heavy weight of this microscope section, it is difficult to control the position adjustment, the entire device becomes large, and furthermore, there are disadvantages such as being affected by the vibrations of the cooling fan of the laser device. Since the above-mentioned method using optical fiber does not have such drawbacks, it is expected to be put into practical use in recent years.

[Problems to be Solved by the Invention] By the way, when used for the above-mentioned purposes, a condensing device that converges laser light emitted from the output end of an optical fiber must generally satisfy the following conditions. is requested.

■ The focused spot diameter should be as small as possible.

This is necessary to increase the energy density, facilitate processing, and enable microfabrication.

■ The required distance between the laser beam emitting end of the condenser and the workpiece can be secured.

This is because during processing, it is often impossible to bring the laser beam emitting end close to the workpiece. For example, in the case of laser trimming mentioned above, a probe is placed between the laser beam emitting end and the workpiece to measure the resistance value of the workpiece, so this probe arrangement requires a A minimum distance must be maintained.

However, in a normal focusing optical system, if the above-mentioned condition (1) is satisfied, the condition (2) cannot be satisfied, and vice versa. That is, because the core diameter and the numerical aperture (NA) of the output end face of the optical fiber are limited, it has not been possible to fully satisfy both requirements with conventional light condensing devices. Therefore, a laser trimmer device that satisfies the above conditions has not yet been put into practical use.

The present invention has been made against the above-mentioned background, and is a light condenser that can sufficiently reduce the condensed spot diameter and at the same time secure the necessary distance between the laser beam emitting end and the workpiece. The object of the present invention is to provide a laser trimmer device using the device and its condensing device.

[Means for Solving the Problems] The present invention solves the above problems by having the following configurations.

(1) In a condensing device that condenses a laser beam guided from a laser device by an optical fiber and emitted from an output end of the optical fiber and irradiates it onto a target, a diverging laser emitted from the output end of the optical fiber. A configuration characterized by comprising a diverging lens system that further diverges light and a converging lens system that focuses the diverging laser light.

(2) In configuration (1), the diverging lens system is configured with a two-group lens system having a negative focal length, and the converging lens system is configured with a three-group lens system having a positive focal length. Characteristic configuration.

(3) In a laser trimmer device that performs trimming by focusing a laser beam guided from a laser device by an optical fiber and emitted from an output end of the optical fiber onto a trimming position of an object to be trimmed, the laser beam emitted from the optical fiber is focused on a trimming position of an object to be trimmed. A configuration characterized in that the condensing device according to claim 1 or 2 is used as a condensing device for condensing the laser beam at a trimming position of an object to be trimmed.

[Function] According to configuration (1), the laser beam emitted from the optical fiber is further diverged by the diverging optical system and then focused by the focusing optical system, so the aperture of the focusing optical system is set to a necessary and sufficient aperture. This makes it possible to maintain a sufficiently small focused spot diameter while ensuring a necessary distance between the laser beam emitting end and the workpiece.

Further, according to configuration (2), the diverging lens system is formed into an ellipse by two lens groups having a negative focal length, and the converging lens system is configured by a three group lens system having a positive focal length. , with a relatively small number of lens configurations, various aberrations can be kept sufficiently small, and the condensing magnification can be made sufficiently small.
It becomes possible to obtain a condensing device that can ensure a sufficient distance between the laser beam emitting end and the workpiece.

Furthermore, according to configuration (3), fine trimming can be easily performed, and the probe for resistance measurement can be arranged with a sufficient distance between the laser beam emitting end and the workpiece. It is also possible to obtain a laser trimmer device that can be easily used.

[Example] FIG. 1 is a cross-sectional view of a light condensing device according to an example of the present invention,
Fig. 2 is a diagram showing the lens arrangement of the condensing device of one embodiment, Fig. 3 is a diagram showing the lens data of the condensing device of one embodiment, and Fig. 4 is a diagram showing the lens aberration of the condensing device of one embodiment. Figure 5 showing
The figure is a configuration diagram of a laser trimmer device according to an embodiment of the present invention. An embodiment of the present invention will be described in detail below with reference to these drawings.

In FIG. 1, numeral 1 is a first group lens having a negative focal length, numeral 2 is a second group lens having a negative focal length, numeral 3 is a third group lens having a positive focal length, and numeral 4 is a positive lens group. 5 is a 5th group lens having a positive focal length, 6 is an optical fiber, 7 is an optical fiber end fitting, 8 is a fixed frame, and 9 is a 1st group lens. Lens spacing ring between lens 1 and second group lens 2, reference numeral 10
11 is a moving frame, and 11 is a second group lens 2 and a third group lens 3.
12 is a lens spacing ring between the third group lens 3 and the fourth group lens, 13 is a lens spacing ring between the fourth group lens and fifth group lens, and 14 is a lens holding ring. be.

This light condensing device basically consists of a fixed frame 8 and a movable frame 10.

The fixed frame 8 has a small diameter portion on one side of the cylindrical body, that is, the left side in the figure, forming an optical fiber joint 8a, and a large diameter portion on the other side, that is, the right side in the figure. This is used as a lens system joint portion 8b.

The moving frame 10 has a small diameter portion on one side of the cylindrical body, that is, the left side in the drawing, forming a small diameter fitting portion 10a, and a large diameter portion on the other side, that is, the right side in the drawing. The objective portion 10b has a large diameter.

An optical fiber end fitting 7 is inserted and fixed inside the optical fiber joint portion 8a of the fixed frame 8.

The output end of the optical fiber 6 is inserted and fixed into this optical fiber end fitting. Therefore, the optical fiber 6 is fixed to the fixed frame 8 such that its output end face faces the lens system joint 8b side of the fixed frame 8.

Furthermore, a small-diameter fitting portion 10a of the movable frame 10 is fitted and held in the lens system fitting portion 8b of the fixed frame 8 so as to be movable in the axial direction. In addition, the mechanism that allows free movement in the axial direction is
For example, a female thread is provided on a part of the inner circumferential surface of the lens system fitting part 8b of the fixed frame 8, and the small diameter fitting part 10a of the moving frame 10 is provided with a female thread on the - side.
It is possible to adopt a mechanism in which a male thread is provided on a part of the outer circumferential surface of the holder and the external threads are screwed together. In that case, the stopper pin 8C is screwed into a through hole formed in the lens system fitting portion 8b of the fixed frame 8 so that it can be fixed at a desired position.

A lens group is housed and fixed within the movable frame 10. In other words, the first group lens 1 and the second group lens 2 are placed in the small diameter fitting part 10a, and the third group lens 3, the fourth group lens 4, and the second group lens are placed in the large diameter objective part 10b. The 5th group lens 5 is
They are held one after another at predetermined intervals toward the right. Note that between each of these lenses, a lens spacing ring 9, a lens spacing ring 11, a lens spacing ring 12, and a lens spacing ring 13 are arranged to set the respective lens spacings. Further, the fifth group lens is fixedly held by a lens holding ring 14.

Here, the apertures of the third group lens 3 and the fourth group lens held in the large diameter objective part 10b are larger than the apertures of the first group lens 1 and the second group lens 2 which are fitted and held in the small diameter fitting part 10a. Group lens 4
And the aperture of the fifth group lens 5 is large.

Further, by moving the movable frame 10 with respect to the fixed frame 8, the distance X1 between the output end face of the optical fiber 6 and the first group lens 1 can be changed.

Now, this condensing device collects the diverging laser beam Li emitted from the end face of the optical fiber 6 through the first group lens 1, second group lens 2, third group lens 3, fourth group lens 4, and fifth group lens. 5
The light Lr is made into a focused light Lr, and the light is focused on a focal point P.

Next, the first group lens 1, the second group lens 2, the third group lens 3, the fourth group lens 4, and the fifth group lens will be explained.

FIG. 2 is a diagram showing the arrangement of these lenses. As shown in FIG. 2, M1, M2, M3, M4, M5, M
6, M7, M8, M9, Mlo surface numbers are attached. Also, the spacing between these tiles is dl, d2, d3, respectively.
Let d4, d5, d6, dl, and d8.

In such a case, the radius of curvature (r; unit m
m), interplanar spacing (d; unit mm), and refractive index (N; wavelength 1
1064n) have the values shown in FIG. In addition, in Fig. 3, the aperture of each lens is φ2.
The diameter is approximately 0 mm, and the glass type is high refractive index glass.

FIG. 4 shows various aberrations of the condensing device of this example.

Figure 4(a) shows spherical aberration, and the vertical axis (H
) is the ray height (unit: mm), and the horizontal axis is the distance from the Gaussian image plane (unit: mm).

In addition, the curve shown as a solid line in the figure has a wavelength of 11064
This is a spherical aberration curve for an Nd-YAG laser beam of n, and the curve (SC) indicated by a chain line is a sine condition curve.

In addition, FIG. 4(b) shows astigmatism, where the vertical axis (Y') of the figure is the image height (unit: mm), and the horizontal axis is the distance from the Gaussian image plane (unit: mm). mm). In addition, the curve shown by the solid line (DS> in the figure is the unit of spherical image plane position; mm), and the curve shown by the chain line (DT) is the unit of meridional image plane position; mm), respectively. It is the distance from the Gaussian image plane.

Furthermore, Fig. 4 (,c) shows the distortion aberration, and the vertical axis (Y゛〉) or image height (unit: mm) is the vertical axis of the figure, and the horizontal axis is the amount of distortion (unit: (%) )).

As is clear from FIG. 4, each amount of aberration shows an extremely small value.

Now, with the light condensing device of the above-mentioned example, the following light condensing characteristics were obtained.

*Laser light used: Nd-YAG laser light with a wavelength of 11064n *Output core diameter of optical fiber halo: 0.2 m, mm *Output divergence angle of optical fiber halo; θ=10.4° *Optical fiber 6 and first group lens 1 The distance from the plane of incidence of 'f4
: Xl = 21 mm *Distance between the exit surface of the fifth group lens and the focal point P; X2-=
16 mm *Focusing angle; θ' = 29.76 * Spora [diameter; 0.07 mm *Magnification; θ/θ' = 0.35 According to the above-mentioned embodiment, Nd-Y with a wavelength of 11064
Using AG laser light, focus spot diameter is 0.07mm
m (70 μmφ: magnification of about 1/3). Conventional focusing optical systems for laser trimming have a focusing diameter of 10
Since the limit was 0 μmφ (magnification: 1/2), a sufficient processing condensing diameter was obtained compared to this. Moreover, since the amount of each aberration is extremely small, it is possible to obtain a high-quality spot with a uniform energy distribution. Furthermore, the fifth
The distance NX2 between the exit surface of the group lens 5 and the focal point P is 16 mm.
Therefore, the installation of the probe 7 for measuring the current value becomes extremely easy, and the operability can be improved. In addition, lenses such as those used in this example can be manufactured relatively easily.

Next, a laser trimmer device according to an embodiment will be described.

As shown in FIG. 5, the laser trimmer device of this embodiment is composed of a laser trimmer main body 20, a dust collector 30, a control computer 40, and a measurement system 50.

Inside the laser trimmer main body 20, there are a laser oscillator 21, a condenser 22, an optical fiber 23 that guides the laser beam from the laser oscillator 21 to the condenser 22, and a fiber that sets the position of the condenser. The drive system 23a, the position setting table 25 on which the object to be trimmed 24 is placed, the position controller 26 that controls the positions of the fiber drive system 23a and the position setting table 25, and the position controller 25 and the laser oscillator 21 are controlled. controller 2
7, and a probe 28 for measuring the resistance value of the object 24 to be trimmed.

In this case, as the light condensing device 22, the light condensing device according to the above-mentioned embodiment is used.

The control computer 40 controls the probe 28 and the measurement system 50.
The resistance value of the object to be trimmed 24 measured through the laser is inputted, this measured value is compared with a preset target resistance value, and a predetermined command signal is sent to the controller 27 based on the comparison result. By controlling the oscillator 21 and the position controller 26, the object to be trimmed 24 is subjected to a predetermined laser processing process, and the resistance value of the object to be trimmed 24 is controlled to be a target resistance value. Note that the powder of the resistor remaining after processing the resistor is removed by the dust collector 30.

In the laser trimmer device according to this embodiment, since the focusing device of the above-mentioned embodiment is used as the focusing device 22, the laser beam can be focused to a sufficiently small spot diameter, so that precise processing is possible. The probe 28
This makes installation extremely easy and resistance measurement easy.

Next, a modification of the light condensing device according to an embodiment of the present invention will be described.

FIG. 6 is a sectional view of a modified example of the condensing device according to an embodiment of the present invention, FIG. 7 is a diagram showing the lens arrangement of the modified example, FIG. 8 is a diagram showing lens data of the modified example, and FIG. 9 is a diagram showing lens data of the modified example. The figure is a diagram showing lens aberration of a modified example.

This modified example has exactly the same configuration as the condensing device of the above-mentioned embodiment, except for the differences in values such as the radius of curvature of the lens used and the surface spacing. The explanation thereof will be omitted by assigning the same reference numerals to the parts.

Furthermore, the displays of lens data and lens aberrations shown in FIGS. 8 and 9 are different from those shown in FIGS. In this case, the same display method is used except that the lens aperture is about 35 mm in diameter, so the explanation thereof will be omitted.

As is clear from FIG. 9, even in this modification, each amount of aberration shows an extremely small value.

Now, according to the light condensing device of the above-mentioned modification, the following light condensing characteristics were obtained.

*Laser light used: Nd-YAG laser light with a wavelength of 11064n *Output core diameter of optical fiber 6: 0.2 mmφ *Output divergence angle of optical fiber 6; θ 10.46 *Incidence between optical fiber halo and first group lens 1 Distance to surface:X
1=21mm *Distance between the exit surface of the 5th group lens and the focal point F); X2=
16mm *Focusing angle; θ'=41.6°*Spot diameter; 005mmφ *Magnification; θ/'θ'=0.25 According to the above modification, the spot diameter is 5 Q B mφ
(Magnification: 1/74 times), which was able to be made even smaller than in the previous example.

Note that the present invention is not limited to the above-mentioned embodiment, and can be applied to laser beams of various wavelengths by selecting the glass type and characteristics of each lens according to the wavelength of the laser beam to be focused. Of course.

For example, it is also possible to use a laser (wavelength: 0.533 μm), which is a harmonic of a Nd-YAG laser (fatigue length: 1.064 μm).

[Effects of the Invention] As detailed above, the present invention basically provides a diverging lens system that further diverges the diverging laser beam emitted from the output end of an optical fiber, and a converging lens system that focuses the diverging laser beam. By adopting a configuration including the following, it is possible to obtain a condensing device that can secure the necessary distance between the laser beam emitting end and the workpiece while maintaining the condensed spot diameter sufficiently small. In addition, by using this light condensing device, a laser trimmer device is obtained that allows for precise resistance adjustment with good operability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a light condensing device according to an embodiment of the present invention;
Fig. 2 is a diagram showing the lens arrangement of the condensing device of one embodiment, Fig. 3 is a diagram showing the lens data of the condensing device of one embodiment, and Fig. 4 is a diagram showing the lens aberration of the condensing device of one embodiment. Figure 5 showing
Figure 6 is a configuration diagram of a laser trimmer device according to an embodiment of the present invention, Figure 6 is a sectional view of a modified example of a condensing device according to an embodiment of the present invention, and Figure 7 is a diagram showing the lens arrangement of the modified example. , FIG. 8 is a diagram showing lens data of a modified example, and FIG. 9 is a diagram showing lens aberrations of the modified example. 1... 1st group lens, 2... 2nd group lens, 3...
・3rd group lens, 4... 4th group lens, 5... 5th group lens
Group lens, 6... Optical fiber, 7... Optical fiber end fitting, 8... Fixed frame, 9, 11, 12, 13...
Lens spacing ring, 10... moving frame, 14... lens holding ring.

Claims (1)

[Scope of Claims] (1) In a condensing device that condenses a laser beam guided from a laser device by an optical fiber and emitted from an output end of the optical fiber and irradiates it onto an object, the optical fiber output end What is claimed is: 1. A condensing device comprising: a diverging lens system that further diverges a diverging laser beam emitted from the beam; and a converging lens system that converges the divergent laser beam. (2) In the condensing device according to claim (1), the diverging lens system is composed of two groups of lens systems having a negative focal length, and the converging lens system is composed of three groups having a positive focal length. A light condensing device characterized by being composed of a lens system. (3) In a laser trimmer device that performs trimming by focusing a laser beam guided from a laser device by an optical fiber and emitted from an output end of the optical fiber onto a trimming position of an object to be trimmed, the laser beam emitted from the optical fiber is focused on a trimming position of an object to be trimmed. A laser trimmer apparatus characterized in that the condenser according to claim 1 or 2 is used as a condenser for condensing the laser beam at a trimming position of an object to be trimmed.