JPH11188491A - Laser processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing device, which can be miniaturized and is suitable for precision processing with high accuracy. SOLUTION: A processing table 11, on which a workpiece is put, is composed of a rigid body, and driven by a precision Z stage 13 movable in the optical axial direction of the laser light and a rough moving X-Y stage 14 movable in a vertical direction against the optical axial direction. A measuring system for a distance measurement and a coordinate measurement is arranged on the table 11, and a reference plane for positioning is set at a reference table 12 which is equipped with a laser optical system and composed of the rigid element. Thus, only the relative position relation of a processing point and the laser optical system is measured so as to carry out the positioning control of the table 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam processing apparatus, and more particularly to a laser processing apparatus capable of positioning and irradiating a focused point of a laser beam on a workpiece with high accuracy.

[0002]

2. Description of the Related Art A laser processing apparatus performs processing by irradiating a laser beam generated by a laser oscillator to a workpiece through a laser optical system including a reflecting mirror and an optical lens.
Usually, the workpiece is mounted on a moving stage. The moving stage moves the workpiece so that the processing point on the workpiece is at the irradiation position of the laser beam.

In order to perform precision processing by laser light using such a moving stage, it is necessary to irradiate the processing point with a laser beam focusing point with high accuracy.
A high-precision positioning device used for such processing is special and large-scale.

That is, in high-precision precision machining,
In order to prevent the position of the laser optical system and the processing point from being displaced due to the distortion of the device, the device requires high rigidity and is large-scale. Further, in order to obtain a high-precision positioning device, a special guide mechanism is required for the moving stage.

Referring to FIG. 9, a conventional laser processing apparatus will be described. The laser processing apparatus includes a moving stage 31 movable in the XY directions (horizontal plane) and the Z direction (vertical direction), a laser optical system including a laser oscillator 32, and a gantry 33 for installing the laser optical system. Including. A processing table 3 for mounting a workpiece on the moving stage 31
4 are provided. The moving stage 31 is made of ceramics so that vibration and distortion do not occur. In addition, an air slider is adopted as a stage guide mechanism in order to suppress undulations caused by the movement of the moving stage 31. Further, the moving stage 31 and the gantry 33 are mounted on the anti-vibration table 37 so that the effect of the movement of the moving stage 31 is not transmitted to the laser optical system.
Installed on top.

The laser optical system includes a reflecting mirror 35 for changing the angle of the laser light generated by the laser oscillator 32 to guide the laser light to a through hole provided in the gantry 33 and a laser light on a processing table 34. A processing lens 36 for focusing and irradiating the processing point of the workpiece with light.

[0007]

As described above, when an air slider is used for the moving stage 31, the entire moving stage 31 becomes large, and a high gantry 33 for incorporating the laser optical system is required. In addition, the high frame 33
In order to give the rigidity, the stand 33 needs to have a sufficiently thick foot.

For the reasons described above, there is a problem that a conventional laser processing apparatus, particularly a laser processing apparatus for performing high-precision precision processing, becomes large.

An object of the present invention is to provide a laser processing apparatus which can be downsized and is suitable for high-precision precision processing.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a laser processing apparatus for performing processing by irradiating a laser beam generated by a laser oscillator to a workpiece through a laser optical system including a reflecting mirror and an optical lens. With a table,
A precision Z stage capable of moving with high resolution in the optical axis direction of the laser beam irradiated on the workpiece, and a coarse Z stage mounted with the precision Z stage and capable of moving with high resolution on a horizontal plane perpendicular to the optical axis direction. A dynamic XY stage, and a gantry for providing the laser optical system above the processing table, and a portion of the gantry on which the laser optical system is mounted is configured as a reference table. The laser beam is applied to the workpiece through a through hole provided in the reference table, and the apparatus further includes a distance between the processing table and a predetermined portion of the reference table. A plurality of distance meters for measuring, coordinate measuring means for measuring the coordinates of the processing table, and calculating a tilt and a rotation angle of the processing table based on measurement results from the plurality of distance meters; Calculation results and Control means for controlling the coarse XY stage and the precision Z stage using the measurement results of the coordinate measuring means, wherein only the processing table and the reference table are made of a highly rigid material. And

It is preferable that the plurality of distance meters and the coordinate measuring means are respectively provided on the processing table.

The coordinate measuring means can be realized by a plurality of XY encoders.

[0013] Further, as the plurality of distance meters, three distance meters that irradiate a predetermined portion of the reference table with light and receive the reflected light to measure the distance are provided outside the work mounting area of the processing table. Is preferably provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to FIGS. In the following description, the direction of the optical axis of the laser beam applied to the workpiece is the Z axis (vertical direction in FIG. 1), and the plane perpendicular to the optical axis is the XY plane (FIG. 1).
(Middle, horizontal direction).

In FIG. 1, the present apparatus includes a processing table 1
1, a reference table 12, a precision Z stage 13, a coarse XY stage 14, a laser oscillator 15, a laser reflecting mirror 16, and a processing lens 17 are provided. The processing table 11 is provided on a precision Z stage 13, and the precision Z stage 13
-Provided on the Y stage 14. Precision Z stage 13
The coarse movement XY stage 14 does not require a special guide mechanism. The reference base 12 is for mounting a laser optical system including a laser oscillator 15, a laser reflecting mirror 16, and a processing lens 17, and is a part of the gantry 18. However, unlike the material of the gantry 18, rigidity is required. High material is adopted. The coarse XY stage 14 and the gantry 18 are
Provided above.

In FIG. 2, a first scale 21-1 and a second scale 21 are provided at a position adjacent to a laser beam passing hole 12-1 provided in the reference base 12 and on a lower surface of the reference base 12. -2 is provided.

In FIG. 3, a first distance meter 22-1, a second distance meter 22-2, and a third distance meter 22 are provided on the processing table 11 at positions outside the mounting area of the workpiece 19 mounted thereon. 22-3, a first XY encoder 23-1, and a second XY encoder 23-2 are provided. First distance meter 22-1, second distance meter 22-2, and third distance meter 22-
Numerals 3 each measure a distance between the reference table 12 and the lower surface thereof. That is, the first distance meter 22-1,
Each of the second distance meter 22-2 and the third distance meter 22-3 measures the distance by irradiating the lower surface of the reference base 12 with a light beam and receiving the reflected light. Since such a distance measuring device using light is well known, a detailed description thereof will be omitted. Of course, the first distance meter 22-1, the second distance meter 22-2,
The third distance meter 22-3 is not limited to a distance measuring device using light, and may use other well-known measuring devices.

The first XY encoder 23-1, the second XY encoder
Each of the Y encoders 23-2 has a first scale 21-
This is for measuring the coordinates of the processing table 11 on the XY plane in combination with the first and second scales 21-2, which is also well known. To put it simply, the first scale 21-1 and the second scale 21-2 are each provided with a grid-like stripe pattern as a scale, and are called grid plates. First XY encoder 23-
1. The first and second XY encoders 23-2 irradiate the first scale 21-1 and the second scale 21-2 with light beams, receive the reflected light, and measure the coordinates from the positional relationship of the scales. And is called a scanning head. Therefore, the first XY encoder 23-1 and the second XY encoder 23-2 are provided to face the first scale 21-1 and the second scale 21-2, respectively.

In any case, the first distance meter 22-1, the second distance meter 22-2, the third distance meter 22-3, the first XY encoder 23-1, and the second XY encoder 23-2 ,
It is used as a measurement system for controlling the alignment of the processing table 11.

The mounting structure of each of the above components will be described.

The first distance meter 22-1 and the second distance meter 22-
2. Third rangefinder 22-3, first XY encoder 23-
1, the second XY encoder 23-2 is a processing table 1
1 is fixed with screws or the like. The workpiece 19 is fixed to the processing table 11 by vacuum suction or the like.

The processing table 11 is fixed to the precision Z stage 13 with screws or the like. The precision Z stage 13 has a short stroke but can be moved with high resolution in the Z-axis direction. The precision Z stage 13 also has a coarse movement X that can move in the XY plane with a long stroke and high resolution.
-It is fixed to the Y stage 14 with screws or the like.

A laser oscillator 15, a laser reflecting mirror 16, and a processing lens 17 are fixed to the reference table 12 with screws or the like, and the focal point of the laser beam can be adjusted to a desired position.

The working table 11 is made of a material having sufficiently high rigidity so that the positional relationship between the attached components does not change due to bending or the like. Similarly, the reference base 12 is configured so that the positional relationship between the attached components does not change. As a material having high rigidity for the processing table 11 and the reference table 12, for example, a material such as ceramic can be cited, but a material such as aluminum or stainless steel may be used.

By performing coordinate calculation in a three-dimensional space, which will be described later, using the above-described measurement system, the relative position between the focal point of the laser beam and the processing point on the workpiece 19 can be obtained.

The processing table 11 can be moved to an arbitrary position in a three-dimensional space by a coarse movement XY stage 14 and a fine movement Z stage 13. Therefore, by performing processing by moving the position of the processing point so as to match the focal point of the laser beam, fluctuations in the Z-axis direction due to mounting errors of the coarse movement XY stage 14 and the like are corrected by the fine movement Z stage 13, High-precision precision processing becomes possible.

This apparatus does not require such high rigidity except for the working table 11 and the reference table 12. Also, precision Z
The stage 13 and the coarse XY stage 14 do not require such high straightness and repeatability.

Next, the function of the measurement system will be described with reference to FIGS. FIG. 4 is a diagram for explaining a reference coordinate system set on the reference base 12. The reference coordinate system is fixedly set on the reference base 12. The reference coordinate system is represented by X, Y, and Z with the intersection point between the lower surface of the reference base 12 and the laser beam passing therethrough as the origin. In this case, the coordinates of the focal point of the laser light F (0,0, f _Z) is represented by the fixed coordinate origin of the working table 11 for this _{O T (T X, T Y} ,
T _Z ).

On the other hand, as shown in FIG.
Considering a coordinate system fixed to 1, this coordinate system is represented by x, y, z with the origin at the center of the machining surface. Each distance meter 2
Coordinates of the sensor head of 2-1～22-3 is S _n (s _nx,
s _ny , s _nz ), and each XY encoder 23-1,
Coordinates of the sensor head 23-2 E _n (e _nx, 0,
e _nz ). The coordinates of the processing point are W (w _x ,
w _y , 0).

The reading of each rangefinder is represented by D _n ,
The reading in the X direction of each XY encoder is _Xn and Y
The direction readings are each represented by Y _n . Note that n
Represents the number of a range finder or an XY encoder. In the case of a range finder, n takes 1, 2, and 3, and in the case of an XY encoder, n takes 1, 2.

The rotation angle of the machining table fixed coordinate system with respect to the reference coordinate system is represented by φ for the x axis, ψ for the y axis, and θ for the z axis. And
Since φ, ψ, and θ are minute values, if these values are α, sin α = α, cos α = 1, sin
² It is approximated as α = 0.

Using the above expressions, FIG.
Reading values D ₁ , D of the third distance meters 22-1 to 22-3
₂ and D ₃ are respectively represented as follows.

D ₁ = T _Z −s _1z −Δs _1x −φs _1y (1) D ₂ = T _Z −s _2z −Δs _2x −φs _2y (2) D ₃ = T _Z −s _3z −Δs _3x −φs _3y (3) With regard to equation (1), (T _z −s _1z )
(A) is a distance in the Z-axis direction from the sensor head, and {s _1x is a distance component in the Z-axis direction caused by the rotation angle around the y-axis as shown in FIG. 6 (b). Here, φs _1y is a distance component in the Z-axis direction caused by the rotation angle φ about the x-axis as shown in FIG. 6C. Here, s _nx , s _ny , and s _nz are respectively the distance meters 22-1.
To 22-3, which are determined at the time of design. Further, since D _n is a read value of each rangefinder, T _Z , ψ, and φ can be obtained by simultaneously solving the above equations (1), (2), and (3).

Next, the read value of each XY encoder is expressed as follows.

X ₁ = T _X + e _1x -ψ (T _Z -e _1z ) (4) Y ₁ = T _Y + θ · e _1x -φ (T _Z -e _1z ) (5) Y ₂ = T _Y + θ · _{e 2x -φ (T Z -e 2z} ) (6) where, theta · e _1x is a coordinate components caused by the rotation angle theta, as shown in FIG. 7 (a), ψ (T Z -e _1z )
Is a coordinate component caused by the rotation angle ψ as shown in FIG. 7B, and φ (T _Z -e _1z ) is a coordinate component caused by the rotation angle φ as shown in FIG. 7C. Component. _Here , _enx and _enz are the coordinates of the sensor head of each XY encoder, and are determined at the time of design. X _n , Y _n
Is the reading of each XY encoder. Furthermore, ψ,
Since φ has already been obtained by the above-described method, T _x , T _y , and θ can be obtained by solving the above equations (4) to (6).

Using the values obtained as described above,
The coordinates of the processing point W in the reference coordinate system are determined as follows.

W (T _X + w _x −θ · w _y , T _Y + w _y +
θ · w _x , T _Z + ψ · w _x + φ · w _y ) Since the focal point of the laser beam is F (0,0, f _Z ), the coarse movement X is performed in a direction to reduce the difference between these coordinate points to zero. By moving the -Y stage 14 and the fine movement Z stage 13, the processing point can be focused on the laser beam with high accuracy.

The above calculation is performed by a control unit (not shown) from the measurement results of the first to third distance meters 22-1 to 22-3 and the first and second XY encoders 23-1 and 23-2. This is performed based on the obtained coordinates, and the driving of the coarse movement XY stage 14 and the fine movement Z stage 13 is controlled based on the calculation result.

The progress of the above calculation will be described in order.

1. First to third distance meters 22-1 to 22-3
Each measure the distance from the reference platform 12. As a result, the position of the machining table 11 in the Z-axis direction with respect to the reference table 12 and the inclination with respect to the XY plane can be calculated.

2. Further, the first and second XY encoders 2
3-1 and 23-2 are the first and second scales 21 respectively.
The position in the XY direction with respect to -1, 21-2, that is, the coordinates, is measured. As a result, the reference table 1 of the machining table 11
2 and the rotation angle θ about the Z axis in the XY direction
Can be calculated.

3. Laser oscillator 15, laser reflector 1
6 and the processing lens 17 are fixed to the reference table 12, so that the position of the focal point of the laser beam with respect to the reference table 12 is always the same. Therefore, if the processing point on the workpiece 19 is given by the position with respect to the processing table 11, the relative position between the focal point of the laser beam and the processing point can be calculated.

4. The precision Z stage 13 is set so that the difference between the calculated position of the focal point of the laser beam and the position of the processing point is set to zero.
Is moved in the Z-axis direction, and the coarse movement XY stage 1 is moved.
4 is moved on the XY plane to perform processing.

FIG. 8 shows a process in which the processing table 11 is positioned through the above-described steps 1-4.

The laser processing apparatus according to the present invention can be applied to micromachine processing, a wire bonder, or a stepper in a semiconductor manufacturing apparatus.

Although the present invention has been described with reference to a preferred embodiment, various modifications are possible. For example, the coordinate measuring means by a plurality of XY encoders may be any as long as it can measure the relative position between the processing table 11 and the reference table 12, and for example, a measuring device by image processing is arranged on the reference table 12 side. A deviation of a specific point on the processing table 11 from the reference position is detected, or the laser
, And a laser light reflecting mirror is provided on the processing table 11.

[0047]

As described above, according to the present invention, it is possible to reduce the parts required for high rigidity and to use a general guide mechanism for each stage. In addition, the cost can be reduced, and a laser processing apparatus suitable for high-precision precision processing can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a laser processing apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a diagram for explaining a scale used for measuring coordinates of a processing table in the present invention.

FIG. 3 is a view for explaining a distance meter and an XY encoder provided on a processing table for distance measurement and coordinate measurement in the present invention.

FIG. 4 is a diagram for explaining reference coordinates set on a reference base in the present invention.

FIG. 5 is a diagram for explaining a fixed coordinate system set in a processing table in the present invention.

FIG. 6 is a diagram for explaining a value read by a distance meter in the present invention.

FIG. 7 is a diagram for explaining a read value by an XY encoder in the present invention.

FIG. 8 is a diagram for explaining a correction operation by a precision Z stage according to the present invention.

FIG. 9 is a diagram showing a schematic configuration of a conventional laser processing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Support stand 11, 34 Processing table 12 Reference stand 13 Precision Z stage 14 Coarse movement XY stage 15, 32 Laser oscillator 16, 35 Laser reflecting mirror 17, 36 Processing lens 18, 33 Mounting base 19 Workpiece 21-1, 21 -2 1st, 2nd scales 22-1, 22-2, 22-3 1st, 2nd, 3rd distance meters 23-1, 23-2 1st, 2nd XY encoder 37 Vibration isolation table

Claims (4)

[Claims] 1. A laser light generated by a laser oscillator,
A laser processing apparatus that performs processing by irradiating a workpiece through a laser optical system including a reflecting mirror and an optical lens. The laser processing apparatus is equipped with a processing table and moves with high resolution in the optical axis direction of the laser light applied to the workpiece. A possible precision Z stage, a coarse XY stage mounted with the precision Z stage and capable of moving at a high resolution on a horizontal plane perpendicular to the optical axis direction, and the laser optical system above the processing table. And a mount for mounting the laser optical system in the mount, the laser light is passed through a through-hole provided in the reference mount, and the laser beam is processed by the workpiece. The apparatus further comprises: a plurality of distance meters for measuring a distance between the processing table and a predetermined portion of the reference base; and a seat of the processing table. A coordinate measuring means for measuring,
Calculating a tilt and a rotation angle of the processing table based on the measurement results from the plurality of distance meters; and using the calculation results and the measurement results of the coordinate measuring means, the coarse XY stage and the precision Z stage. A laser processing apparatus, comprising: a control means for controlling the temperature of the laser beam; and only the processing table and the reference table are made of a material having high rigidity. 2. The laser processing apparatus according to claim 1, wherein each of the plurality of distance meters and the coordinate measuring means are provided on the processing table. 3. A laser processing apparatus according to claim 2, wherein said coordinate measuring means comprises a plurality of XY encoders. 4. The laser processing apparatus according to claim 3, wherein, as the plurality of distance meters, three distance meters that irradiate a light beam on a predetermined portion of the reference base and receive reflected light to measure a distance, A laser processing apparatus provided outside a mounting area of a workpiece on the processing table.