JPH10263872A - Laser beam machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out laser machining in a smooth shape for the curved part of a machining locus. SOLUTION: The machine is provided with a mask 2 that has a slot, whose distance between the center points is (d) and whose radius is (r), on the optical axis of an incident laser beam and that is turnable around the optical axis; a mask rotating and driving means 4; and a controller 10 which calculates and outputs the following command and which performs the next laser beam irradiation after the completion of the positioning. The command is for moving a stage 6 for a prescribed distance so that, in laser machining along a curved locus, the laser beam irradiation is stopped after the irradiation at a prescribed position on this locus, that the mask 2 is then rotated while the stage 6 is moved, that the rear side circle center after the moving of the slot is superposed on the front side circle center before the moving, and that the center line connecting the center points of the slot after the moving comes into contact with the curve; and also for rotating the mask 2 at a prescribed angle by the mask rotating and driving means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam machine for cutting or etching a workpiece into an arbitrary shape, particularly a fine curved shape, at a high speed with a laser beam.

[0002]

2. Description of the Related Art In recent years, optical communication systems have become more practical due to the development of optical cable networks, and optical cables and optical waveguide components have been widely developed in order to cope with this. . One of the important requirements for these developments is to manufacture inexpensively, in large quantities, and with high precision, optical waveguides for connecting a large number of optical circuit components mounted on a substrate. ing.

Conventionally, as one of means for responding to the above demand, for example, “ELECTRONICS LETTERS 7th December 1995
Vol.31 No.25 ”. According to this laser beam drawing apparatus, a silicon substrate to be processed is set on a precision movement XY stage having submicron precision, which can move in two orthogonal directions perpendicular to each other, and a laser beam oscillated from a krypton laser oscillator is applied to a predetermined position. Guiding the mask having a hole having a shape, moving the stage while irradiating the target substrate with laser light transmitted through the mask, and drawing an optical waveguide pattern of an arbitrary shape on the silicon substrate to produce an optical waveguide. Is available.

On the other hand, by moving the irradiation position of the laser beam transmitted through the mask by a predetermined distance,
When performing fine processing such as etching and cutting as described above, it is necessary to steepen the gradient of the energy density at the outer peripheral portion of the spot beam in order to form a sharp edge after processing. The slope of the energy density does not become steep only by the ordinary laser focusing method as shown in FIG. 9 (1), and the laser beam is transmitted through the mask and the outer peripheral portion is formed as shown in FIG. 9 (2). This purpose is achieved by reducing and projecting after cutting.

[0005]

However, in the above-mentioned conventional laser beam machine, a mask is used as a mask.
For example, those having holes such as circular, square, and rectangular are used, and when irradiating such a mask with a laser beam to draw a precise curve such as an optical waveguide pattern,
The following problems occur. 1) In the curved portion of the optical waveguide, it is necessary to process smoothly so that irregular reflection of light does not occur. For this purpose, a circular mask may be used. However, in this case, as shown in FIG. 10, the stage (the substrate) is moved by a predetermined distance.
Since the laser irradiation position is moved, the number of irradiations differs between the center and the end of the trajectory of the laser beam. For this reason, the integrated irradiation energy amount calculated by the formula “irradiation energy amount = pulse energy density (substantially constant value) × number of irradiations” differs between the center and the end of the trajectory, and uniform processing cannot be performed. Further, when the moving distance between the irradiation positions is reduced to make the integrated irradiation energy amount uniform, there is a problem that the production speed is reduced and the productivity is reduced.

2) When a mask having a square or rectangular hole is used, as shown in FIG. 11 or FIG. 12, the integrated irradiation energy amount on the trajectory becomes substantially uniform. Are shifted by a predetermined distance in parallel in both directions, so that the shape of the processing locus becomes jagged. As a result, when an optical waveguide is manufactured, a loss due to irregular reflection of light at a curved portion increases, which is a problem.

The present invention has been made in view of the above problems, and has as its object to provide a laser processing machine capable of processing a curved portion of a processing locus with a smooth shape.

[0008]

In order to achieve the above object, the present invention is directed to a mask 2 having a hole having a predetermined shape for transmitting a laser beam oscillated from a laser oscillator. And orthogonal 2 by the stage driving means
A laser processing machine that is provided with a stage 6 that is moved in the axial direction and on which a work 7 is placed on the upper surface, and that irradiates the work 7 with laser light transmitted through the mask 2 to draw a trajectory of an arbitrary shape. , The distance between the center points is d and the radius is a long hole 21 on the optical axis of the incident laser light.
a said mask 2 having said hole and being rotatable about said optical axis, mask rotation driving means 4 for rotating said mask 2 about said rotation axis, and a laser along a predetermined curved trajectory. When processing, the irradiation is stopped after irradiating the laser beam at a predetermined position on this trajectory, and then the mask 2 is rotated while moving the stage 6 to move the mask 2 behind the elongated hole 21a after the movement. The center of the circle on the side overlaps the center of the circle on the front side before the movement, and the elongated hole 21 after the movement
a a command to move the stage 6 by a predetermined distance by the stage driving means so that a center line connecting the center points of FIG.
And outputs a command to rotate the mask 2 by a predetermined angle, outputs a laser beam after the completion of the positioning, and repeats the above processing.

According to the first aspect of the present invention, the mask can be rotated about the laser optical axis, and the shape of the hole provided on the laser optical axis of the mask is changed by the distance between the center points of the semicircles on both sides. Is d and the radius is a long hole of r. When the irradiation position of the laser beam transmitted through the hole is moved, the center of the rear circle after the movement of the long hole of the mask overlaps the center of the front circle before the movement, and The movement of the stage and the rotation of the mask are controlled so that the center line connecting the center points of the holes is in contact with the curve of the processing locus. As a result, even if the mask is rotated by a predetermined angle along the processing locus, the locus shape of the overlapping portion becomes smooth, so that a smooth processing locus can be obtained even in a curved portion. Further, since the moving distance of the irradiation position can be increased, the workable distance per unit time can be increased, and the productivity can be improved.

According to a second aspect of the present invention, in the laser beam machine according to the first aspect, the mask 2 has a long hole 21b in which an outer convex portion of a semicircle having the radius r is cut out by a predetermined distance.
Is provided.

According to the invention described in claim 2, according to claim 1,
Since the semicircular outer convex portion of the long hole of the mask described above is cut out by a predetermined distance, the movement of the stage and the rotation of the mask are controlled in the range of the mask maximum allowable rotation angle corresponding to the cutout amount, as in the preceding paragraph. Then, the center of the circle on the rear side after the movement of the long hole of the mask overlaps the center of the circle on the front side before the movement, and the center line connecting the center points of the long holes after the movement corresponds to the curve of the processing locus. Make contact. As a result, even if the mask is rotated by a predetermined angle along the processing locus, the locus shape of the overlapping portion becomes smooth, so that a smooth processing locus can be obtained even in a curved portion. Further, compared with the case of the long hole without the notch, even if the length of the long hole is the same, the distance between the center points can be increased by the length of the notch, so that the moving distance of the irradiation position is further increased. Therefore, productivity can be further improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a laser beam machine according to the present invention will be described with reference to the drawings. FIG. 1 is a hardware configuration diagram illustrating an example of the embodiment. The laser beam L emitted from the laser oscillator 1 is guided to the mask 2, passes through a predetermined hole provided in the mask 2, and enters the condenser lens 5. The condenser lens 5 reduces and condenses the laser light L, and
Irradiate the work 7 installed on the upper surface of the work. The stage 6 is provided so as to be movable in two orthogonal (XY) directions, and each axis is driven by an X-axis driving unit 8 and a Y-axis driving unit 9. The X-axis driving means 8 and the Y-axis driving means 9 have an X-axis servo motor 8a and a Y-axis servo motor 9a, respectively, and the rotation of these servo motors is controlled in each axial direction by a transmission mechanism such as a ball screw and a nut. And the stage 6 is driven.

The mask 2 is provided so as to be rotatable about an axis parallel to the optical axis, and is rotationally driven by a rotation driving means 4 via a gear 3. The rotation drive unit 4 is configured by an electric motor such as a stepping motor or a servo motor. The gear 3 includes a gear 3 a on the mask side provided on the outer periphery around the rotation axis of the mask 2, and a gear 3 b provided on the output shaft of the rotation driving means 4.

The controller 10 is constituted by a computer device mainly including a microcomputer, for example.
The controller 10 calculates and outputs drive command values to the X-axis driving means 8 and the Y-axis driving means 9 and performs control for positioning the stage 6 at a predetermined position. Further, a rotation command value to the rotation driving means 4 is calculated and output, and the mask 2 is controlled to a predetermined angle. Further, the output of laser light from the laser oscillator 1 is controlled by turning on / off a Q switch (not shown), for example. In the case of a pulsed laser such as an excimer laser, on / off of laser oscillation is controlled by outputting an oscillation command (eg, a pulse signal) to the laser.

In the following, two embodiments of the shape of the hole provided in the mask 2 will be described. FIG. 2 is a plan view of the mask 2 according to the first embodiment. A hole 21 having a center coinciding with the center of rotation of the mask 2 is provided in the center of rotation of the mask 2 having a circular outer shape. In the present embodiment, as an example of the hole 21, a rectangular hole and a semicircular shape located on one of two opposite sides (short side of the rectangle in the drawing) of the two pairs of opposite sides of the rectangular hole. A long hole 21a formed by connecting the holes is provided. The gear 3a is attached to the outer periphery of the mask 2. The distance between the centers of the semicircular circles of the elongated holes 21a is d, and the width in the direction perpendicular to the line connecting the centers of the circles is w. Therefore, the radius r of the semicircular holes is represented by the formula "r = w / 2 ". Further, the length L in the longitudinal direction of the long hole 21a is represented by a mathematical expression “L = d + w”.

Next, a smooth curve processing method using the laser processing machine having the above configuration will be described with reference to FIGS.
It will be described based on. FIG. 3 shows an irradiation locus when an optical waveguide is manufactured. As shown in the figure, by irradiating the laser light on the left and right outer sides of the trajectory of the optical waveguide 15, the irradiated portion is finally removed, and the portion surrounded by the left and right irradiation paths remains to form the optical waveguide 15. Is done. Therefore, in this case, it is necessary to smooth the right and left curved portions of the irradiation path. Similarly, the irradiation position can be moved to cut a member having an arbitrary shape. In this case, the curved portions on the left and right of the irradiation path need to be smooth.

FIG. 4 shows a mask 2 during processing of a curved portion.
Of the laser beam transmitted through the long hole 21a. Now, let it be assumed that the curve 16 is a mask movement trajectory as a processing target, and that the current mask position is represented as "2n". At this time, the next mask position 2n + 1 is calculated so as to satisfy the following condition. First, the mask position 2n before movement is placed at the center of the semicircular hole on the rear side with respect to the movement direction at the mask position 2n + 1 after movement of the irradiation position.
The center of the semicircular hole on the front side of is overlapped. next,
The rotation angle of the mask 2 is such that the center line 17 connecting the centers of the two semicircular holes of the long hole 21a is tangent to the curve 16. As a result, the irradiation positions before and after the movement overlap only at the portion corresponding to the semicircular hole, and the overlapping semicircular circles have the same radius.
The left and right trajectories are no longer jagged, resulting in a smooth trajectory. Therefore, when the curve 16 is represented by an arc having a predetermined radius of curvature, as shown in FIG.
1) = line segment (2n + 1-2n) ". Further, assuming that the center of the arc is O, the mask position 2n-1 is P, the mask position 2n is Q, and the mask position 2n + 1 is R, the mask position 2n satisfies the expression "angle OQP = angle OQR". +1 is calculated.

FIG. 6 shows an example of a method of calculating the moving distance of the stage 6 and the rotation angle of the mask 2 when the mask 2 is used. In the drawing, the center line of the irradiation trajectory of the processing target is assumed to draw an arc-shaped curve having a radius of curvature R, and the initial position of the elongated hole 21a at the time of processing the curved portion is set to M1, and the mask 2 is sequentially rotated by a predetermined rotation angle α. Slot 21a when rotated
Is defined as Mn (n is a natural number). here,
The following are defined as auxiliary parameters for calculating each position.

## EQU1 ## Mask center radius Rc = R.times.COS (.alpha. / 2)

## EQU2 ## The rotation angle α = 2 × SIN ⁻¹ (d / 2R) At this time, the rotation center position of the mask 2 corresponding to each position M1 and Mn of the long hole 21a (that is, the center position of the long hole 21a). Coordinates (provided that the center of curvature of the arc portion is the coordinate origin) are (X1, Y1), (Xn, Y
n), and the rotation angle of the mask 2 corresponding to the position Mn is θ
Assuming n, each value is represented by the following equation.

X1 = Rc × COS θ1

## EQU4 ## Y1 = Rc × SIN θ1

Xn = r × COS θn

## EQU6 ## Yn = r × SIN θn

## EQU7 ## θn = α / 2 + (n−1) × α

For these reasons, the slot 21a is moved to the position Mn.
The formulas for calculating the moving amounts of the X-axis, Y-axis and θ-axis when moving and rotating are as follows.

## EQU8 ## X-axis moving distance = Xn-Xn-1

## EQU9 ## Y-axis moving distance = Yn-Yn-1

## EQU10 ## When processing an arc-shaped curved locus, the X-axis and the Y-axis for each movement processing step are obtained based on, for example, the above-mentioned arc-shaped curve equation based on the above-mentioned equations. And the movement amount of the θ-axis may be calculated before starting the machining and stored in a predetermined storage area of the controller 10. As a result, C
The calculation load on the PU can be reduced.

FIG. 7 shows an example of a processing flowchart of mask movement control of a curved portion by the controller of the laser beam machine according to the present invention. Hereinafter, a control method will be described with reference to FIG. In S1, XY of the stage 6 before performing the curved part processing
Initial positioning of the axis and the rotation axis of the mask 2 is performed, and a parameter n for processing is set to 0. And S2
Then, the moving distance of the stage 6 and the rotation angle of the mask 2 in each step during the stop of the laser beam irradiation are calculated in advance based on the curve expression (the relational expression between X and Y) representing the processing target trajectory. Remember. In step S3, the value of the parameter n is advanced by one, and in step S4, the Q switch of the laser oscillator 1 is controlled to start laser beam irradiation. Thereafter, in S5, it is determined whether the laser beam irradiation has been completed a predetermined number of times, and S5 is repeated until the predetermined number of times has been completed. When the irradiation has been completed a predetermined number of times, it is next determined in S6 whether or not the optical processing of the curved portion has been completed. If not, in S7, the current (n-th step) calculated in S2 in S7. The stage 6 is moved in the X-axis and Y-axis directions based on the moving distance and the rotation angle, and the mask 2 is rotated. Thereafter, the process returns to S3 and the above process is repeated. In step S6, when the optical processing of the curved portion is completed, the process proceeds to an end process, and this flow is completed.

In the above description, an example is shown in which the center of rotation of the mask 2 coincides with the center of the elongated hole 21a, that is, the center between the two semicircular center points, but the present invention is not limited to this. Instead, for example, the center of rotation may be set at a predetermined position in the elongated hole 21a. In particular, when the center of rotation is coincident with one of the center points of the two semicircles of the elongated hole 21a, the arithmetic processing in each step of the moving distance of the stage 6 and the rotation angle of the mask 2 is very simple. become.
That is, in this case, for example, assuming that the current rotation angle of the mask 2 with respect to the X axis is θn, the moving distance in the next moving step is “X axis moving distance = d × COS (θn)”, “Y axis moving distance”. = D × SIN (θn) ”.
The axis rotation angle is set such that the center line of the elongated hole 21a is in contact with the curve of the predetermined locus when the center of rotation of the elongated hole 21a is rotated when the center of rotation after the movement is overlapped with the center point of the front half circle before the movement (in the case of an arc,
(It becomes equal to the rotation angle α in Equation 2).

Next, a second embodiment will be described. This embodiment shows an example in which the shape of the hole 21 is different from that of the previous embodiment, and FIG. 8 is a diagram showing the hole 21 of the mask 2 in this example. Except for the shape of the hole 21, it is the same as the previous embodiment, so only the hole 21 will be described here. The mask 2 has a rectangular hole 25 as the hole 21, and a semicircular outer protrusion located on one of two pairs of sides (short side of the rectangle in the figure) of the two pairs of opposite sides of the rectangular hole 25. An elongated hole 21b is provided which is connected to the notched hole 26. The distance between the centers of the semicircular circles of the elongated hole 21b is d1, the width in the direction perpendicular to the line connecting the centers of the circles is w, and the radius r of the semicircular hole is (w
/ 2). At this time, the notch distance A is expressed by the following equation.

A = r [1−SIN (θs / 2)] Here, θs is a mask for smoothing the trajectory shape of the overlapping portion of the irradiation position when moving the stage 6 for each moving step. 2, which is set to a predetermined angle from the relationship between the radius of curvature of the target machining locus and the center-to-center distance d1.

Further, the longitudinal length L of the long hole 21b is
It is represented by the formula "L = d1 + 2rSIN (.theta.s / 2)".
Therefore, if the longitudinal length L of the long hole 21b is equal to the longitudinal length L of the long hole 21a in the previous embodiment, the following relational expression is established.

D1 = d + 2A Therefore, the pitch of the moving distance of the stage 6 can be increased, so that the processing speed can be increased as compared with the previous embodiment, and the productivity can be improved.

The control flow of the controller when using the mask 2 having such a long hole 21b is shown in FIG.
This is the same as the flowchart example shown in FIG. That is, when the curved portion is processed using the mask 2 having the elongated holes 21b, similarly to the above, the center of the virtual semicircle of the hole 26 on the rear side after the movement of the irradiation position is positioned on the front side before the movement. The mask 2 is moved while the stage 6 is moved such that the center of the circle of the virtual semicircle overlaps and the center line 17 connecting the centers of the two holes 26 of the long hole 21b is tangent to the curve of the target locus. It is rotated by a predetermined rotation angle α. At this time, the rotation angle α is equal to or smaller than the maximum allowable rotation angle θs. This enables laser processing in which the outer contour of the processing locus of the curved portion is extremely smooth.

As described above, the mask 2 having the long hole 21a or the long hole 21b on the optical axis of the incident laser light is rotatable around the optical axis, and the work 7 to be processed is set on the upper surface. The stage 6 is movable in two orthogonal directions. Then, the laser beam transmitted through the mask 2 is irradiated onto the work 7 and then stopped. During this irradiation stop, the mask 2 is rotated by a predetermined angle while horizontally moving the work 7 in the orthogonal two-axis directions by a predetermined distance. The center of the front semicircle before the movement of the long hole coincides with the center of the rear semicircle after the movement, and the longitudinal center line of the long hole is in contact with the curve. As a result, the irradiation positions overlap only in the semicircular portion, so that the laser beam can be processed smoothly without contours of the irradiation trajectory. Therefore, it is possible to configure a laser processing machine capable of forming a very smooth curve even when processing along a trajectory having a curved portion, for example, manufacturing an optical waveguide on a substrate, or cutting an arbitrary shape. Further, since the moving distance between the irradiation positions is increased, the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a hardware configuration diagram illustrating an example of a laser processing machine according to the present invention.

FIG. 2 is a plan view of a mask of the first embodiment of the laser beam machine according to the present invention.

FIG. 3 shows an irradiation trajectory when an optical waveguide is manufactured by the laser beam machine according to the present invention.

FIG. 4 is an explanatory diagram of a locus of movement of a mask hole at the time of processing a curved portion in the first embodiment according to the present invention.

FIG. 5 is an explanatory diagram of a calculation method of a mask moving distance and a rotation angle at the time of processing a curved portion in the first embodiment according to the present invention.

FIG. 6 is an explanatory diagram of a calculation method of a mask moving distance and a rotation angle at the time of processing a curved portion in the first embodiment according to the present invention.

FIG. 7 shows an example of a flowchart of mask movement control at the time of processing a curved portion by the laser beam machine according to the present invention.

FIG. 8 shows a plan view of a mask of a second embodiment of the laser beam machine according to the present invention.

FIG. 9 is an explanatory diagram of an operation of laser beam reduction projection using a mask according to the related art.

FIG. 10 is an explanatory diagram of an operation of laser processing using a circular mask according to the related art.

FIG. 11 is an explanatory diagram of an operation of laser processing using a rectangular mask according to the related art.

FIG. 12 is an explanatory diagram of an operation of laser processing using a rectangular mask according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Mask 3 Gear 4 Rotation drive means 5 Condensing lens 6 Stage 7 Work 8 X-axis drive means 8a X-axis servomotor 9 Y-axis drive means 9a Y-axis servomotor 10 Controller 15 Optical waveguide 16 Curve 17 Center line 21 hole 21a long hole 21b long hole (notch semicircle) 25 rectangular hole 26 hole (notch semicircle)

Claims (2)

[Claims] 1. A mask (2) having a hole of a predetermined shape for transmitting a laser beam oscillated from a laser oscillator, and a work (7) which is moved in two orthogonal directions by a stage driving means and is set on an upper surface. A laser beam transmitted through the mask (2) to irradiate the work (7) with a laser beam that has passed through the mask (2) to draw a trajectory of an arbitrary shape. On the axis, the distance between the center points is d,
And, having the above-mentioned hole having a radius of r (21a),
The mask (2) rotatable about the optical axis; mask rotation driving means (4) for rotating the mask (2) about the rotation axis; and laser processing along a predetermined curved locus. Sometimes, after the laser beam irradiation at a predetermined position on this trajectory, the irradiation is stopped,
Next, the mask is moved while moving the stage (6).
By rotating (2), the center of the rear circle after the movement of the long hole (21a) of the mask (2) overlaps the center of the front circle before the movement, and the long hole (21a) after the movement. A command to move the stage (6) by a predetermined distance by the stage driving means so that a center line connecting the center points of the trajectories contacts the curve of the locus, and the mask (2) by the mask rotation driving means (4).
And a controller (10) for calculating and outputting a command to rotate the laser beam by a predetermined angle, irradiating the next laser beam after completion of the positioning, and repeating the above processing. 2. The laser beam machine according to claim 1, wherein the mask (2) has an elongated hole (21b) in which an outer convex portion of the semicircle having the radius r is cut out by a predetermined distance. Laser processing machine.