TWI527650B - Laser processing apparatus - Google Patents

Description

Laser processing device

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus for irradiating a laser beam along a predetermined line to form a cutting groove on a surface of a brittle material substrate.

As a technique for dividing a brittle material substrate such as a glass substrate, a segmentation method using crack progress has been proposed. In this method, first, a primary crack is formed on the surface of the glass substrate by a cutter wheel or the like. Thereafter, the laser beam is scanned along the line to be cut to heat the substrate, thereby cooling the heated area immediately after the irradiation of the laser beam. Thereby, the crack progresses along the planned cutting line to form a cutting groove.

The laser beam scanned along the line to be cut has a predetermined length along the scanning direction. In order to form a laser beam as described above, an optical system including a spherical lens and a cylindrical lens, or an optical system including two cylindrical lenses in which the directions in which the bus bars extend are orthogonal to each other is used.

The intensity distribution of the laser beam formed by the optical system as described above in the beam scanning direction is a gauss type. That is, the intensity of the laser beam is the strongest in the central portion in the longitudinal direction of the beam, and becomes weaker as it proceeds toward both ends. According to the laser beam of the optical system as described above, it is not possible to form a cutting groove. Is the most appropriate intensity distribution of the laser beam.

Therefore, in Patent Document 1, there is proposed a processing system capable of making the intensity distribution of the laser beam uniform in the direction along the line to be cut. The processing system is provided with: a laser oscillator, a mirror, and a polygon mirror for reflecting a laser beam emitted by the laser oscillator, the polygon mirror being used for A laser beam reflected by the mirror is scanned on the substrate.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-212364.

In the system described in Patent Document 1, the laser beam emitted from the laser oscillator is reflected by the mirror through the mirror, and is repeatedly scanned along a predetermined line on the substrate and over a predetermined length. . By this reverse scanning, the intensity distribution of the predetermined length of the laser beam in the direction along the line to be cut is uniform.

However, in the system described in Patent Document 1, since the irradiation angle changes with respect to the surface of the substrate of the laser beam reflected by the polygon mirror, the intensity distribution of the laser beam is not uniform, resulting in closer proximity. The intensity of the end portion of the laser beam irradiation range formed by the repeated scanning becomes lower. Further, it is only possible to set the intensity of the laser beam on the substrate to the same intensity distribution, and it is difficult to appropriately respond to various substrate specifications, processing conditions, and the like.

An object of the present invention is to make the intensity of a laser beam on a substrate the same in the longitudinal direction of the beam or the width direction of the beam by a simple configuration and processing.

A further object of the present invention is to easily achieve optimum processing conditions. The intensity distribution of the laser beam.

A laser processing apparatus according to a first aspect of the invention is directed to irradiating a laser beam along a planned cutting line to form a cutting groove on a surface of a brittle material substrate, the laser processing apparatus including: a laser beam emitting device; a laser beam for emitting a Gaussian-type intensity distribution; a carrier for placing a substrate of a brittle material to be processed; a first lens for controlling a beam width in a direction orthogonal to a planned cutting line; and a second lens a beam length for controlling the direction along the line to be cut; a cooling device for cooling the region heated by the laser beam on the substrate of the brittle material; and a scanning mechanism for the laser beam and The cooling device performs relative scanning on the substrate of the brittle material placed on the stage. Further, at least one of the first lens and the second lens is an aspherical cylindrical lens, and the intensity distribution of the laser beam having the Gaussian-type intensity distribution incident thereon is set on the brittle material substrate. The beam width direction or the beam length direction is the same.

In the processing apparatus, the laser beam emitted from the laser beam emitting device is irradiated onto the brittle material substrate by the first lens and the second lens. In addition, the laser beam is scanned by a scanning mechanism along a line of cut of the brittle material substrate. The substrate heated by the laser beam is cooled by a cooling device that scans together with the laser beam, and a cutting groove is formed along a predetermined line of cutting of the substrate. Here, since at least one of the first lens and the second lens is an aspherical lens, the intensity distribution in the width direction and/or the longitudinal direction of the laser beam is made the same.

Here, a laser beam having a substantially rectangular intensity distribution can be easily obtained compared to a system using a conventional polygonal mirror. Further, particularly when the intensity distribution in the longitudinal direction of the laser beam is made the same, it is easy to form the dicing groove. Process optimization.

A laser processing apparatus according to a second aspect of the invention is the apparatus of the first aspect of the invention, wherein the second lens is an aspherical cylindrical lens for converting an intensity distribution of the beam.

Here, the intensity distribution in the longitudinal direction of the laser beam along the planned cutting line of the laser beam irradiated on the brittle material substrate can be made the same. Therefore, it is possible to prevent the temperature of the substrate from rising until the cooling is performed by the cooling device. Therefore, the tensile stress at the time of cooling can be increased, and the processable conditions of the dicing groove can be further enlarged. That is, the cutting margin is increased.

In the laser processing apparatus according to the third aspect of the invention, the first lens and the second lens are both aspherical lenses for converting the intensity distribution of the beam.

Here, the intensity distribution of the laser beam can be set to be the same in the width direction of the laser beam and in the longitudinal direction along the line to be cut. Therefore, the cutting margin can be further enlarged.

A laser processing apparatus according to a fourth aspect of the present invention, characterized in that the apparatus of any one of the first to third aspect, further comprising: a moving mechanism for causing each of the first lens and the second lens to independently follow the optical axis Move in the direction.

By moving each lens in the direction along the optical axis, the length in the width direction and the longitudinal direction of the beam can be changed, and the processing can be optimized.

In the laser processing apparatus according to a fifth aspect of the invention, the apparatus of any one of the first to fourth invention is characterized in that the offset mechanism is provided to move the aspherical cylindrical lens in a direction orthogonal to the optical axis.

By offsetting the aspherical cylindrical lens, the shape of the intensity distribution of the laser beam can be changed. Thereby, it is possible to change the form in which the temperature of the substrate rises, and it is possible to optimize the processing.

A laser processing apparatus according to a sixth aspect of the present invention, characterized in that, in any one of the first to fifth inventions, a beam diameter control mechanism for controlling a diameter of a laser beam incident on the aspherical cylindrical lens is provided .

The shape of the intensity distribution of the laser beam can be changed by changing the diameter of the laser beam incident on the aspherical cylindrical lens. Therefore, the optimization of the processing can be achieved in the same manner as in the fifth invention.

In the present invention as described above, by making the lens constituting the optical system an aspherical cylindrical lens, it is possible to simply set the intensity of the laser beam on the substrate to be in the longitudinal direction of the beam or to shoot. The width of the bundle is the same.

1‧‧‧bearing station

2‧‧‧heating mechanism

3‧‧‧Cooling nozzle

4‧‧‧Loading platform drive mechanism

11‧‧‧Laser oscillator

12‧‧‧ Beam expander

13‧‧‧Mirror

14, 15‧‧‧ aspherical cylindrical lens

18‧‧‧Ball diameter control mechanism

21, 22‧‧‧1st, 2nd mobile agency

23, 24‧‧‧1st, 2nd offset mechanism

G‧‧‧glass substrate

Fig. 1 (a) and (b) are schematic configuration diagrams of a laser processing apparatus according to an embodiment of the present invention.

Figure 2 is a graph showing the surface temperature distribution of a rectangular beam and a Gaussian beam.

Figure 3 is a graph showing the surface stress distribution of a rectangular beam and a Gaussian beam.

Figure 4 is a graph showing the cutting margin of a rectangular beam.

Figure 5 is a graph showing the cutting margin of a Gaussian beam.

Fig. 6 is a view showing the intensity distribution when the aspherical cylindrical lens is moved in the Z-axis direction.

Figure 7 is a graph showing the intensity distribution when changing the beam diameter of a laser beam incident on an aspherical cylindrical lens.

Fig. 8 is a view showing the intensity distribution when the aspherical cylindrical lens is shifted from the optical axis.

Figure 9 is a graph showing the intensity of the aspherical cylindrical lens when it is offset from the optical axis. The map of cloth.

Fig. 10 is a view showing the intensity distribution when the aspherical cylindrical lens is shifted from the optical axis.

[Laser processing device]

Fig. 1 shows a laser processing apparatus according to an embodiment of the present invention. The laser processing apparatus includes a stage 1, a heating mechanism 2, a cooling device (in the first figure, only the cooling nozzle (Nozzle) 3 constituting the cooling device), and a stage driving mechanism (scanning mechanism) 4; The stage 1 is for mounting a glass substrate G to be processed; the heating mechanism 2 is for heating the glass substrate G on the stage 1; the cooling device is for cooling the glass heated by the heating mechanism 2. The substrate G; the stage driving mechanism 4 is for moving the stage 1 in the X and Y planes. In addition, Fig. 1(b) is a view of Fig. 1(a) viewed from different 90° directions.

The heating mechanism 2 includes a laser oscillator 11 as a laser emitting device, a beam expander 12, a mirror 13, a first aspherical cylindrical lens 14, and a second aspherical cylindrical lens 15. Further, the heating mechanism 2 includes a beam diameter control mechanism 18, first and second moving mechanisms 21 and 22, and first and second offset mechanisms 23 and 24.

Laser oscillator 11 based e.g. CO ₂ laser device is used to exit. The intensity of the laser beam emitted from the laser oscillator 11 shows a Gaussian distribution. The beam expander 12 is composed of three lenses, and can change the gap in the optical axis direction of each lens. The mirror 13 is configured to reflect the laser beam from the beam expander 12 towards the stage 1 .

The first aspherical cylindrical lens 14 is for collecting the incident laser beam On the glass substrate G, the intensity of the width direction of the laser beam (the direction orthogonal to the planned cutting line) is converted into a lens of a rectangular shape distribution on the glass substrate G. Further, the second aspherical cylindrical lens 15 is for concentrating the incident laser beam on the glass substrate G, and directing the laser beam along the line to be cut on the glass substrate G. The intensity of the lens is converted into a rectangular shape.

The beam diameter control mechanism 18 is a mechanism for controlling the beam diameter of the laser beam by changing the distance between the two lenses of the three lenses constituting the beam expander 12.

The first moving mechanism 21 is a mechanism for moving the first aspherical cylindrical lens 14 in the Z-axis direction (height direction) to change the beam width on the glass substrate G. Further, the second moving mechanism 22 is configured to move the second aspherical cylindrical lens 15 in the Z-axis direction to change the beam length (length along the direction of the planned cutting line) on the glass substrate G. mechanism.

The first offset mechanism 23 is configured to shift the first aspherical cylindrical lens 14 in the Y-axis direction (the beam width direction orthogonal to the planned cutting line) orthogonal to the optical axis to change the glass. A mechanism for the intensity distribution in the beam width direction on the substrate G. Further, the second offset mechanism 24 is configured to shift the second aspherical cylindrical lens 15 in the X-axis direction (direction along the line to cut) orthogonal to the Y-axis in the horizontal plane to change A mechanism for the intensity distribution in the longitudinal direction of the beam on the glass substrate G.

The cooling device injects the refrigerant supplied from a refrigerant source (not shown) through the cooling nozzle 3 to form a cooling spot. This cooling point is formed at the rear end portion of the laser beam irradiated on the glass substrate G in the scanning direction.

[Cutting method]

When the dicing groove is formed in the glass substrate G by the above-described processing apparatus, first, a cutter roller or the like is used to form a preliminary portion as a starting point of the cutting at the end portion of the glass substrate G. Cracked. In addition, the initial crack can also be formed by a laser.

Next, a laser beam is emitted from the laser oscillator 11, and the laser beam is irradiated onto the glass substrate G via the divergence beam expander 12, the mirror 13, and the first and second aspherical cylindrical lenses 14, 15. on. At this time, the intensity distribution of the laser beam is converted from a Gaussian distribution to a rectangular shape by the first and second aspherical cylindrical lenses 14 and 15 in both the beam width direction and the beam length direction. . The laser beam scans the glass substrate G along the line to cut according to the movement of the stage 1 by the stage driving mechanism 4. The glass substrate G is heated by a laser beam to a temperature lower than the softening point of the glass substrate G. In addition, the cooling point follows the trailing end of the scanning beam in the scanning direction.

According to the above manner, although compressive stress is generated in the vicinity of the region heated by the irradiation of the laser beam, since the cooling point is formed immediately after the injection of the refrigerant, effective stretching is formed for the formation of the vertical crack. stress. By the tensile stress, a vertical crack is formed along the line to be cut, and a desired cutting groove is formed.

[The intensity of the laser beam is divided]

Here, a laser beam having a Gaussian distribution of intensity distribution (hereinafter referred to as "Gaussian beam") and a laser beam having a distribution of a rectangular shape according to the present embodiment (hereinafter referred to as "rectangular beam") The difference is explained.

Fig. 2 is a graph showing the temporal change of the surface temperature at a certain position on the substrate when the rectangular beam and the Gaussian beam are scanned on the glass substrate. In Fig. 2, the solid line is the temporal change of the surface temperature when a rectangular beam is used, and the one-point chain line is a temporal change of the surface temperature when a Gaussian distribution is used. In addition, the horizontal axis of Fig. 2 is time [sec], and the vertical axis is temperature [°C]. Further, the laser beam has a length of 60 mm, a width of 1.5 mm, and a scanning speed of 120 mm/s. In addition, the cooling system is at the rear end of the scanning direction of the laser beam. get on.

As is apparent from Fig. 2, when the Gaussian beam is heated, the substrate surface temperature is gradually increased, and the laser beam becomes maximum at a time point of passing about 2/3, and then falls. On the other hand, in the case of heating by a rectangular beam, the temperature rises sharply and the temperature rise continues until the moment of cooling. In this example, the rectangular beam is about 150 ° C larger than the Gaussian beam.

Fig. 3 is a graph showing temporal changes in surface stress at a certain position on a substrate when scanning a rectangular beam and a Gaussian beam on a glass substrate. In Fig. 3, the solid line is the temporal change of the surface stress when a rectangular beam is used, and the one-point chain line is a temporal change of the surface stress when the Gaussian beam is used. In addition, the horizontal axis of Fig. 3 is time [sec], and the vertical axis is stress [Mpa]. In addition, the size and scanning speed of the laser beam are the same as in the second drawing.

It is known from Fig. 3 that the compressive stress is maximum at the center of the beam when heated by a Gaussian beam, which is -83 MPa in this example. After that, the compressive stress will drop and it will be -17Mpa before the cooling moment. On the other hand, in the case of heating by a rectangular beam, the compressive stress gradually increases toward the rear end of the beam after the front end of the beam is sharply increased to about -60 MPa. The compressive stress before the moment of cooling is -74 MPa. Further, the tensile stress at the time of cooling is 150 MPa in the case of a Gaussian beam, 177 MPa in the case of a rectangular beam, and about 18% in the case of a rectangular beam.

According to the above, the following are known.

In the heating of the rectangular beam, since the tensile stress at the time of cooling becomes large, it can be predicted that the condition range in which the cutting groove can be formed is widened by the heating by the Gaussian beam, and even the cutting margin (margin) )expand. Therefore, the cutting groove shape can be improved The stability of the processing of the time. In addition, the processable conditions can be easily found.

The results of the experiments based on the above predictions are shown in Figs. 4 and 5. Fig. 4 is a view showing the result of cutting whether the cutting groove processing is performed by heating by a rectangular beam. Further, Fig. 5 shows the result of cutting whether the cutting groove is processed by Gaussian beam heating.

It is known from the figures that the dicing groove processor is heated by the rectangular beam to enlarge the cleavable range compared to the case of heating by the Gaussian beam.

[Control of Rectangular Beam]

Here, the shape of the intensity distribution of the rectangular beam can be controlled by changing the positions of the aspherical cylindrical lenses 14, 15. Hereinafter, specific control will be described.

<Z axis direction position>

By changing the position of the aspherical cylindrical lenses 14 and 15 to the position of the glass substrate G, that is, the position in the Z-axis direction by the first moving mechanism or the second moving mechanism, the length of the beam width can be changed and along The length of the beam that cuts the direction of the predetermined line. This situation is shown in Figure 6. In addition, Fig. 6 is a graph showing the intensity distribution in the longitudinal direction of the beam.

It is known from Fig. 6 that if the distance between the aspherical cylindrical lens and the surface of the substrate is increased, the beam length is increased. Only the beam length will change and the shape of the intensity distribution will change.

<shot incident beam diameter>

By controlling the position of each lens of the beam expander 12, the beam diameter of the laser beam incident on the aspherical cylindrical lens can be varied. Also, as shown in Fig. 7, the intensity distribution of the rectangular beam can be changed by changing the beam diameter. In addition, Fig. 7 is a graph showing the intensity distribution in the longitudinal direction of the beam.

Specifically, if the beam diameter is reduced, as shown on the left side of the lower part of Fig. 7, the rectangle of the intensity distribution is broken, so that the intensity of the central portion of the beam is stronger than the both ends, which approximates a Gaussian distribution. Then, if the beam diameter is increased, as shown in the center of the lower portion of Fig. 7, an intensity distribution of a substantially rectangular shape is obtained. Next, if the beam diameter is further increased, as shown on the right side of the following paragraph, the center portion is made weaker than the both end portions.

<offset>

By the first offset mechanism 23 or the second offset mechanism 24, the aspherical cylindrical lenses 14 and 15 are shifted in the direction orthogonal to the optical axis, that is, the intensity distribution and the beam in the beam width direction can be changed. The intensity distribution in the length direction.

Specific examples are shown in Figs. 8 to 10 . Figs. 8 to 10 show the second aspherical cylindrical lens 15 in the state of the center of the lower stage of the seventh drawing, the state of the left side of the lower stage, and the state of the right side of the lower stage, respectively, which are offset in the direction orthogonal to the optical axis. -0.3 to +0.3mm condition.

As can be seen from the figures, by shifting the aspherical cylindrical lens in a direction orthogonal to the optical axis, it is possible to enhance the strength of one of the two ends of the beam from the other. Further, depending on the degree of the offset, it is possible to control the degree of the difference in the strength between the both ends.

As described above, by changing the shape of the intensity distribution of the rectangular beam, it is possible to perform heating with a temperature distribution most suitable for various processing conditions, and it is possible to optimize the processing.

[Other Embodiments]

The present invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the scope of the invention.

(a) In the above embodiment, the aspherical cylindrical lenses 14 and 15 are used to convert the intensity distribution in the width direction and the longitudinal direction of the laser beam into a rectangular shape. Alternatively, only one of the sides may be an aspherical cylindrical lens, and only one side of the intensity distribution may be a rectangular shape.

(b) In the foregoing embodiment, although the beam diameter of the laser beam is changed by one beam expander, the beam diameter for changing the beam width direction and the beam length direction may be independently set. Beam expander.

1‧‧‧bearing station

2‧‧‧heating mechanism

3‧‧‧Cooling nozzle

4‧‧‧Loading platform drive mechanism

11‧‧‧Laser oscillator

12‧‧‧ Beam expander

13‧‧‧Mirror

14, 15‧‧‧ aspherical cylindrical lens

18‧‧‧Ball diameter control mechanism

21, 22‧‧‧1st, 2nd mobile agency

23, 24‧‧‧1st, 2nd offset mechanism

G‧‧‧glass substrate

Claims (5)

A laser processing apparatus irradiates a laser beam along a cutting line to form a cutting groove on a surface of a brittle material substrate, the laser processing apparatus comprising: a carrying platform for placing a substrate of a brittle material to be processed a laser beam emitting device for emitting a laser beam having a Gaussian intensity distribution; a first lens for controlling a beam width in a direction orthogonal to the predetermined cutting line; and a second lens for controlling a beam length along a direction of the aforementioned cutting line; a cooling device for cooling a region of the brittle material substrate heated by the laser beam; and a scanning mechanism for the laser beam and the cooling The device performs relative scanning on the brittle material substrate placed on the carrier; and at least one of the first lens and the second lens is an aspherical cylindrical lens, which is located at a position away from the brittle material substrate. When the position in the direction orthogonal to the optical axis is set to a predetermined position, the intensity distribution of the incident laser beam having a Gaussian-type intensity distribution is set as the beam on the brittle material substrate. The width direction or the beam length direction is the same, and at least one of the first lens and the second lens includes at least one of a moving mechanism and an offset mechanism for moving the aspherical cylindrical lens toward the optical axis. The direction is moved, and the offset mechanism is configured to move the aspherical cylindrical lens in a direction orthogonal to the optical axis. The laser processing apparatus according to claim 1, wherein the second lens is the aspherical cylindrical lens for converting an intensity distribution of a beam. The laser processing apparatus according to claim 1, wherein the first lens and the second lens are both aspherical cylindrical lenses for converting an intensity distribution of a beam. The laser processing apparatus according to claim 1, wherein the moving mechanism is configured to independently move each of the first lens and the second lens in a direction along an optical axis. The laser processing apparatus according to claim 1, further comprising a beam diameter control mechanism for controlling a diameter of a laser beam incident on the aspherical cylindrical lens.