WO2017026747A1 - Laser processing device - Google Patents

Abstract

A laser processing device is disclosed. The disclosed laser processing device comprises: a beam generation unit for emitting a plurality of laser beams; a plurality of scanners for adjusting paths of the plurality of laser beams emitted from the beam generation unit; and a telecentric lens unit allowing laser beams reflected from the scanners to be incident thereon, and condensing the laser beams such that the incident laser beams are vertically incident to a workpiece.

Description

Laser processing equipment

The present invention relates to a laser processing apparatus, and more particularly, to a laser processing apparatus capable of adjusting the position and angle of a laser beam irradiated to a workpiece.

In general, the laser processing process refers to a process of processing a shape or physical properties of the surface of the workpiece by scanning a laser beam on the surface of the workpiece. There may be various examples of such a workpiece, and the shape may be a 2D planar shape. have. An example of a laser processing process may be a process of crystallizing an amorphous silicon film by scanning a laser beam on a silicon wafer to form a polysilicone film.

The quality of the result of this machining process depends on the position, direction, time, etc. at which the laser beam is irradiated onto the workpiece. During the laser processing process, the beam emitted from the light source is divided into a plurality of beams at the same time, or the position at which the laser beam emitted from the light source is irradiated onto the workpiece is moved through the operation of the scanner. However, in this case, the angle at which the laser beam is irradiated onto the workpiece is changed depending on the path of the laser beam. As a result, the processing shape of the workpiece by the laser beam is changed, which may adversely affect the laser processing quality.

Therefore, even when irradiating a plurality of laser beams at the same time or changing the irradiation position of the laser beam, it is necessary to keep the angle at which the laser beam is irradiated to the workpiece constant. In addition, in order to precisely control the machining position, an observation technique capable of observing a laser machining process is required.

The present invention provides a laser measuring apparatus and a laser which can determine whether a laser beam is defective by dividing a laser beam emitted from a laser light source into a measuring beam and a processing beam for a laser processing process, and then measuring optical characteristics of the measuring beam. A processing system and laser measuring method are provided.

In one aspect,

A beam generator for emitting a plurality of laser beams;

A plurality of scanners for adjusting a path of the plurality of laser beams emitted from the beam generator; And

The laser processing apparatus includes a telecentric lens unit configured to receive the laser beams reflected from the scanners and to condense the laser beams so that the incident laser beams are incident perpendicularly to the workpiece.

According to the embodiment, even if there is a fluctuation in the condensing optical system and a change in the thickness of the workpiece, a condensing point detecting device capable of accurately and stably detecting the condensing point position of the processing beam is provided.

1 is a view illustrating a laser beam focused through a general focusing lens unit.

FIG. 2 is a diagram schematically illustrating a laser processing pattern by laser beams passing through the lens unit illustrated in FIG. 1.

3 is a diagram illustrating beams irradiated to a telecentric lens unit according to an exemplary embodiment.

4 is a view schematically showing a laser processing apparatus according to an exemplary embodiment.

5 is a view schematically showing a laser processing apparatus according to another exemplary embodiment.

6 is a view showing an example in which the scanner driver adjusts the position and angle of the scanner.

Fig. 7 is a view showing a laser processing apparatus according to another exemplary embodiment.

8 is a view schematically showing a laser processing apparatus according to another exemplary embodiment.

9 is a view showing an example in which the diffractive optical element shown in FIG. 8 is rotated.

In one aspect,

A beam generator for emitting a plurality of laser beams;

A plurality of scanners for adjusting a path of the plurality of laser beams emitted from the beam generator; And

The laser processing apparatus includes a telecentric lens unit configured to receive the laser beams reflected from the scanners and to condense the laser beams so that the incident laser beams are incident perpendicularly to the workpiece.

The laser beams reflected by the scanners may pass through the aperture center of the telecentric lens unit.

The laser processing apparatus may further include a scanner driver for adjusting the position and angle of the scanners.

The scanner driver may adjust the position and angle of the scanner such that the laser beams reflected from the scanners pass through the aperture center of the telecentric lens unit.

The laser processing apparatus may further include a photographing unit configured to photograph the laser beams emitted from the telecentric lens unit being irradiated onto the workpiece.

The laser processing apparatus may further include a dichroic mirror provided at an aperture of the telecentric lens unit.

The laser processing apparatus may further include an illumination light source irradiating illumination light toward the dichroic mirror.

The dichroic mirror may be configured to transmit light with respect to the wavelength of the laser beams and reflect light with respect to the wavelength of the illumination light.

In another aspect,

Light source;

A diffractive optical element (DOE) for dividing the beam emitted from the light source into at least two;

There is provided a laser processing apparatus including a telecentric lens unit for allowing the beams split by the diffractive optical element to be incident perpendicularly to the workpiece.

The laser processing apparatus may further include a rotation stage for controlling a rotation angle of the first diffractive optical element.

In another aspect,

A beam emitting step of emitting a plurality of laser beams;

Adjusting an optical path of the laser beams such that the plurality of laser beams emitted in the beam exiting step are incident on the telecentric lens unit; And

And condensing the laser beams such that the laser beams are incident perpendicularly to the workpiece by using the telecentric lens unit.

The laser processing method includes: irradiating illumination light toward a dichroic mirror provided in an aperture of the telecentric lens unit; And

Photographing that the laser beams are irradiated onto the workpiece by measuring the illumination light reflected by the workpiece.

In the drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of description. Meanwhile, the embodiments described below are merely exemplary, and various modifications are possible from these embodiments.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from another.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

In addition, terms such as “unit” and “module” described in the specification mean a unit that processes at least one function or operation.

1 is a view showing a state in which a laser beam is focused through a general focusing lens unit 10. In FIG. 1, an example in which the lens unit 10 includes the first to fourth lenses 12, 14, 16, and 18 is illustrated, but this is merely illustrative, and the number of lenses included in the lens unit 10 and The shape can be changed.

Referring to FIG. 1, beams passing through an aperture of the lens unit 10 may form converging points P0, P1, and P2 on the condensing surface through the lens unit 10. The center light of the beam incident in parallel with the optical axis of the lens unit 10 may be irradiated perpendicular to the condensing surface. That is, the angle θ0 between the center light and the light collecting surface may be close to 90 degrees. However, the center light of the beams incident not parallel to the optical axis of the lens unit 10 may be irradiated not perpendicular to the condensing surface. For example, the angle θ1 between the center light of the beam forming the light collecting point P1 and the light collecting surface may be smaller than 90 degrees. Further, the angle θ2 between the center light of the beam forming the light collecting point P2 and the light collecting surface may be smaller than θ1. That is, as the distance between the optical axis and the condensing point of the lens unit 10 increases, the angle between the center light of the beam and the condensing surface may become smaller.

As shown in FIG. 1, even when beams are irradiated into the aperture of the lens unit 10, the shape and angle of incidence of the laser beam are collected on the light collecting surface according to the angle of incidence of the beams.

FIG. 2 is a diagram schematically illustrating a laser processing pattern by laser beams passing through the lens unit 10 illustrated in FIG. 1. FIG. 2A illustrates the laser processing near the optical axis of the lens unit 10, that is, near the condensing point P0. 2B shows a state in which laser processing is performed at a point deviating from the optical axis of the lens unit 10, that is, near the condensing points P1 and P2.

Referring to FIG. 2A, near the optical axis of the lens unit 10, the central beam of the laser beam is irradiated perpendicularly to the workpiece, so that the laser processing pattern may have a symmetrical shape. On the other hand, referring to Figure 2 (b), the center light of the laser beam is irradiated obliquely to the workpiece at the point outside the optical axis of the lens unit 10 may change the laser processing shape. As such, when the laser processing shape is changed, the laser processing quality may be adversely affected.

3 is a diagram illustrating beams being irradiated to the telecentric lens unit 20 according to an exemplary embodiment.

Referring to FIG. 3, light passing through the aperture center C of the telecentric lens unit 20 may be irradiated perpendicularly to the incident plane regardless of the incident angle. Since the telecentric lens unit 20 has an exit pupil close to infinity, the light irradiated with the aperture may be focused in the same shape regardless of the incident angle. However, the location of the focusing point may vary according to the incident angle of the incident beam irradiated to the aperture. For example, a relationship as shown in Equation 1 may be satisfied between the incident angle of the incident beam and the distance between the converging point and the optical axis.

... 수학식 1

... Equation 1

In Equation 1, h is the distance between the focusing point and the optical axis of the telecentric lens unit 20, f is the effective focal length of the telecentric lens unit 20, θ is the optical axis of the telecentric lens unit 20 And the angle between the incident beam. Referring to Equation 1, it can be seen that as the angle between the optical axis of the telecentric lens unit 20 and the incident beam increases, the distance between the condensing point and the optical axis of the telecentric lens unit 20 also increases. Therefore, by adjusting the incident direction of the incident beam, the position of the focusing point can be adjusted. For example, in FIG. 3, a beam incident at an angle of α1 with respect to the optical axis may form a condensing point at a point apart from the optical axis by h1 = f * α1. In addition, a beam incident at an angle of α2 with respect to the optical axis may form a condensing point at a point apart from the optical axis by h2 = f * α2.

3 illustrates an example in which the telecentric lens unit 20 includes one concave lens 22, two convex lenses 26 and 28, and a lens 24 having a concave left side and a convex right side. However, the telecentric lens unit 20 may have any other lens array that can emit light incident on the aperture center C in parallel. In the present invention, the aperture 29 is shown to help understand the invention, but the aperture is for expressing the position and range of the lens characteristics and may not be a component that actually exists. As described above, the beam passing through the telecentric aperture may have an infinite exit pupil, and light incident on the aperture may be condensed in the same shape regardless of the angle of incidence. 2 is a view schematically illustrating a laser processing apparatus according to an exemplary embodiment. The laser processing apparatus shown in FIG. 4 may include the telecentric lens unit 20 shown in FIG. 3. For convenience, the telecentric lens unit 20 is simply shown as a block in FIG. 4.

4, a laser processing apparatus according to an exemplary embodiment may include a beam generator (not shown) for emitting a plurality of laser beams and a path of a plurality of laser beams emitted from the beam generator (not shown). The laser beams reflected from the plurality of scanners 32, 34, 36, 38 and scanners 32, 34, 36, 38 for adjusting the radiation are irradiated, and the laser beams are irradiated perpendicularly to the workpiece. It may include a telecentric lens unit 20 for condensing them.

As shown in FIG. 4, the beam generation unit may inject the first to fourth beams L1, L2, L3, and L4 into the first to fourth scanners 32, 34, 36, and 38, respectively. have. The configuration of the beam generator may be variously changed. For example, the beam generator may include a plurality of light sources. As another example, the beam generation unit divides one light source and a beam emitted from the one light source into a plurality of beams L1, L2, L3, and L4 to the first to fourth scanners 32, 34, 36, and 38. It may also include a beam splitting optical system for transmitting.

In the first to fourth scanners 32, 34, 36, and 38, the first to fourth beams L1, L2, L3, and L4 have the center C of the aperture 29 of the telecentric lens unit 20. Can be passed. Here, the position and size of the aperture of the aperture 29 of the telecentric lens unit 20 may vary depending on the size and lens characteristics of the telecentric lens unit 20. Therefore, the positions and the angles of the first to fourth scanners 32, 34, 36, and 38 may also vary according to the size and lens characteristics of the telecentric lens unit 20.

The first to fourth beams L1, L2, L3, and L4 are centered on the aperture 29 of the telecentric lens unit 20 by the first to fourth scanners 32, 34, 36, and 38. After passing through, the first to fourth beams L1, L2, L3, and L4 may be irradiated to the workpiece 5 in parallel with each other through the telecentric lens unit 20. That is, the first to fourth beams L1, L2, L3, and L4 may be irradiated at the same angle with respect to the workpiece 5. Through this, the plurality of laser beams L1, L2, L3, L4 may be irradiated to the workpiece 5 in the same direction and in the same beam shape. By injecting the plurality of laser beams L1, L2, L3, L4 into the workpiece 5 with the same characteristics at once, the speed of the laser processing process can be increased, and the laser processing quality can be improved.

4 illustrates an example in which the positions and angles of the first to fourth scanners 32, 34, 36, and 38 are fixed so that the laser beams L1, L2, L3, and L4 having the same characteristics are incident on the workpiece 5 at once. Indicated. However, the embodiment is not limited thereto.

5 is a view schematically showing a laser processing apparatus according to another exemplary embodiment. In the description of the embodiment of FIG. 5, the description overlapping with FIG. 4 will be omitted.

Referring to FIG. 5, the laser processing apparatus according to the exemplary embodiment may include a beam generator (not shown) for emitting the first and second laser beams L1 and L2 and the first and second beams L1 and L2. ) May include first and second scanners 31 and 33 respectively irradiated. Here, the number of laser beams and the number of scanners emitted from the beam generator (not shown) are merely exemplary and the present invention is not limited thereto. In the embodiment shown in FIG. 5, the positions and angles of the first and second scanners 31 and 33 may vary. Therefore, the position where the first and second beams L1 and L2 form the light collection point on the workpiece 5 may also vary depending on the position and angle of the first and second scanners 31 and 33.

Although not shown in the drawings, the laser processing apparatus according to the exemplary embodiment may include a scanner driver (not shown) for adjusting the position and angle of the first and second scanners 31 and 33. The scanner driver may adjust the position and the arrangement angle of the scanners 31 and 33. The scanner drive unit positions and angles of the scanners 31 and 33 such that the beams L1 and L2 reflected by the scanners 31 and 33 pass through the center of the aperture 29 of the telecentric lens unit 20. Can be adjusted.

6 is a view showing an example in which the scanner driver adjusts the position and angle of the scanner.

Referring to FIG. 6, when the scanner forms an angle of β1 with the beam emitted from the light source 50, the beam L1 reflected from the scanner is arranged along the optical axis of the telecentric lens unit 20. It can be irradiated perpendicularly to the workpiece 5 past the center of the aperture 29 of 20. Here, as described with reference to Equation 1 to change the position where the beam is focused on the workpiece 5, the angle between the advancing direction of the beam reflected by the scanner and the optical axis of the telecentric lens unit 20 can be changed. have. However, if the angle of the beam reflected from the scanner is adjusted, the beam L21 reflected from the scanner may not pass through the center C of the aperture 29 of the telecentric lens unit 20. Then, even if the beam L21 passes through the telecentric lens unit 20, the workpiece 5 can be irradiated obliquely.

Therefore, the position of the scanner may be changed so that the beam reflected from the scanner passes through the center C of the aperture 29 of the telecentric lens unit 20. That is, as the angle of the scanner is changed from β1 to β2, the position of the scanner may be changed from P1 to P2. Through this, the beam L22 reflected from the scanner is irradiated perpendicularly to the workpiece 5, thereby changing the position at which the beam L22 is irradiated onto the workpiece 5.

In order to precisely control the operation of the scanner driver shown in FIG. 6, it is necessary to measure the laser processing process at any time. To this end, the laser processing apparatus according to the exemplary embodiments illustrated in FIGS. 4 and 5 further includes a photographing unit for photographing that the laser beams emitted from the telecentric lens unit 20 are irradiated onto the workpiece 5. It may include. Hereinafter, an example in which the laser processing apparatus according to the embodiment illustrated in FIG. 5 further includes a photographing unit will be described with reference to the drawings.

Fig. 7 is a view showing a laser processing apparatus according to another exemplary embodiment.

Referring to FIG. 7, the laser processing apparatus according to the embodiment may further include a photographing unit 90. The photographing unit 90 may include a CCD camera 92 and a condenser lens 94 as a device for photographing illumination light reflected from the surface of the workpiece 5. The CCD camera 92 is merely exemplary and may be replaced with another configuration capable of light sensing. Although the illumination light reflected from the surface of the workpiece 5 may use reflected light by laboratory interior lighting, a separate illumination light source 70 may be further provided. If the laser processing apparatus includes a separate illumination light source 70, it is necessary to transmit some of the light from the illumination light source 70 and reflect some of the illumination light reflected from the workpiece 5 toward the CCD camera 92. The beam splitter 96 may be further provided in the photographing unit 90.

In general, the processing laser beams L1 and L2 may also be reflected in the workpiece 5, and when the reflected processing laser beams L1 and L2 are irradiated onto the CCD camera 92 of the imaging unit, only the adverse effects on the captured image may be affected. It may also cause damage to the equipment. In order to prevent this, the laser processing apparatus according to the embodiment may include a dichroic mirror 39 provided in the aperture 29 of the telecentric lens unit 20. The dichroic mirror 39 may transmit or reflect light depending on the wavelength. For example, the dichroic mirror 39 can transmit most of the light to the wavelength of the processing laser beam and hardly reflect it. Through this, the processing laser beams L1 and L2 may be prevented from being irradiated to the photographing unit 90. On the other hand, the dichroic mirror 39 may reflect most of the light with respect to the wavelength of the illumination light emitted from the illumination light source 70. Through this, the illumination light reflected from the workpiece 5 may be transmitted to the photographing unit 90. The position of the dichroic mirror 39 is exemplary and may vary depending on the optical system configuration and the requirements of the product.

The CCD camera 92 of the photographing unit 90 may photograph the illumination light reflected from the workpiece 5 to provide a photographed image. The laser processing process can be checked at any time through the photographed image.

In the above embodiments, embodiments in which a plurality of beams are incident on the telecentric lens unit 20 using a scanner have been described. Hereinafter, an example in which a plurality of beams are incident on the telecentric lens unit 20 by using a diffractive optical element (DOE) will be described.

8 is a view schematically showing a laser processing apparatus according to another exemplary embodiment.

8, the laser processing apparatus according to an exemplary embodiment,

A light source (not shown) for irradiating a laser beam, a diffractive optical element 62 for dividing the beam emitted from the light source into at least two, and beams split from the diffractive optical element 62 are irradiated perpendicularly to the workpiece The telecentric lens unit 20 may be included.

The diffractive optical element 62 may branch out one laser beam irradiated using a diffraction phenomenon of the laser beam. When the laser beam is branched using the diffractive optical element 62, an effect of simultaneously controlling the plurality of laser beams at a plurality of points of the object can be obtained. In addition, the processing form of the object is determined according to the design of the diffractive optical element 62. The beam from the light source can be split into a plurality of beams via the diffractive optical element 62. In addition, the beams split by the diffractive optical element 62 may be irradiated perpendicularly to the workpiece 5 through the telecentric lens unit 20.

In FIG. 8, the divided laser beams are irradiated onto one workpiece line D1 on the workpiece 5. In this state, if the rotation angle θ of the diffractive optical element 62 is 0 °, the position where the laser beam is irradiated on the workpiece 5 is changed by changing the rotation angle θ of the diffractive optical element 62. You can change it.

FIG. 9 is a view showing an example in which the diffractive optical element 62 shown in FIG. 8 is rotated.

Referring to FIG. 9, the diffractive optical element 62 can be rotated at a designated angle (0 <θ <90 °). The laser processing apparatus may include a rotating stage to rotate the diffractive optical element 62. When the diffractive optical element 62 is rotated by the rotating stage, the divided laser beams may be irradiated to different processing lines D1 and D2, respectively. That is, two rows of the workpiece 5 may be simultaneously processed.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

Claims (12)

A beam generator for emitting a plurality of laser beams; A plurality of scanners for adjusting a path of the plurality of laser beams emitted from the beam generator; And And a telecentric lens unit configured to focus the laser beams so that the laser beams reflected from the scanners are incident and the incident laser beams are incident perpendicularly to the workpiece. The method of claim 1, And laser beams reflected from the scanners pass through an aperture center of the telecentric lens unit. The method of claim 1, The laser processing apparatus further comprises a scanner driver for adjusting the position and angle of the scanners. The method of claim 3, wherein And the scanner driver adjusts the position and angle of the scanner such that the laser beams reflected from the scanners pass through the aperture center of the telecentric lens unit. The method of claim 1, And a photographing unit configured to photograph the laser beams emitted from the telecentric lens unit being irradiated onto the workpiece. The method of claim 5, And a dichroic mirror provided at the aperture of the telecentric lens unit. The method of claim 6, And an illumination light source for irradiating illumination light toward the dichroic mirror. The method of claim 7, wherein And the dichroic mirror is configured to transmit light with respect to the wavelength of the laser beams and reflect light with respect to the wavelength of the illumination light. Light source; A diffractive optical element (DOE) for dividing the beam emitted from the light source into at least two; And a telecentric lens unit for allowing the beams split by the diffractive optical element to be incident perpendicularly to the workpiece. The method of claim 9, And a rotation stage for controlling the rotation angle of the diffractive optical element. A beam emitting step of emitting a plurality of laser beams; Adjusting an optical path of the laser beams such that the plurality of laser beams emitted in the beam exiting step are incident on the telecentric lens unit; And And condensing the laser beams such that the laser beams are incident perpendicularly to a workpiece using the telecentric lens unit. The method of claim 11, Irradiating illumination light toward a dichroic mirror provided in an aperture of the telecentric lens unit; And Photographing that the laser beams are irradiated onto the workpiece by measuring the illumination light reflected by the workpiece.

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