JP2003080389A - Device and method for laser beam machining and method for manufacturing product having laser beam machined work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a laser beam machining by homogenizing the distribution of light intensity when a work which is a semiconductor substrate on which a thin film is vapor deposited is heat treated via the thin film with a laser beam. SOLUTION: A laser beam 14 is made incident on a cylindrical face lens 11, condensed into a linear form with the cylindrical face lens 11 to be formed as a linearly condensed beam 15. Further, a lens holder 12 is rotated with a rotational power mechanism 13 and the linearly condensed beam 15 is rotated. Thus, the distribution of light intensity is homogenized by rotating the linearly condensed beam 15.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser processing apparatus,
The present invention relates to a laser processing method and a method for manufacturing an article having a laser-processed workpiece.

[0002]

2. Description of the Related Art Conventionally, as a surface treatment using a laser, for example, a semiconductor substrate such as silicon having a thin film of oxide or metal formed on its surface is heat-treated through the thin film. .

In such surface processing, since the target semiconductor substrate has a large area, as shown in FIG. 5, the laser beam is linearly condensed by a cylindrical lens or the like to form the linear condensed beam 100. The linear condensed beam 100 is applied to the semiconductor substrate 101 placed on the moving table, and the semiconductor substrate 101 is moved to perform surface processing.

[0004]

The laser beam used for such surface processing is a laser beam having a light intensity distribution (that is, multimode) in which a portion having a high light intensity exists in the outer peripheral portion from the beam center, or Since a portion having a high light intensity may be a laser beam having a Gaussian distribution light intensity distribution (that is, a single mode) that exists in the beam center from the outer peripheral portion, in a linear focused beam obtained by linearly focusing it, There is a problem in that the light intensity distribution on the line of the linearly focused beam is not uniform, resulting in inferior processing quality.

The present invention has been made in view of the above problems, and it is an object of the present invention to make the light intensity distribution uniform and enable laser processing.

[0006]

In order to achieve the above object, according to the invention described in claim 1, the laser beam is linearly condensed to form a linear condensed beam, and the linear condensed beam is The laser processing apparatus is characterized in that the laser processing apparatus is configured to rotate about a rotation axis parallel to the propagation direction and to irradiate the workpiece with a beam having a uniform light intensity distribution by the rotation.

As described above, if the linearly focused beam is rotated about the rotation axis parallel to the propagation direction of the linearly focused beam to irradiate the workpiece with a beam having a uniform light intensity distribution,
The processing quality of laser processing can be improved.

In this case, as in the invention described in claim 2, it has a cylindrical lens for linearly focusing the laser beam, and by rotating the cylindrical lens, the linear focused beam is obtained. If the central point of the line length of is the center of rotation and the linear condensed beam is rotated, using a multi-mode laser beam in which a portion with a high light intensity exists in the outer peripheral portion from the beam center Also, the light intensity distribution can be made uniform.

According to the invention described in claim 3, there is provided a cylindrical lens for linearly focusing the laser beam,
By disposing a refracting member for refracting the laser beam to enter the cylindrical surface lens on the incident side of the cylindrical surface lens and rotating the cylindrical surface lens and the refracting member, the line of the linear condensed beam is obtained. If the linearly focused beam is rotated with a position eccentric from the center point of the length as the center of rotation, a single-mode laser beam in which a portion having a high light intensity exists in the beam center from the outer peripheral portion Even if used, the light intensity distribution can be made uniform.

According to the invention described in claim 4, the laser beam is divided into two so as to face each other in a semicircular shape in a cross section in opposite directions, and a two-divided laser beam is generated. A laser processing apparatus configured to deflect the two-divided laser beam so as to linearly condense the deflected two-divided laser beam and irradiate a workpiece with a linear condensed beam. I am trying.

According to the present invention, the light intensity distribution can be made uniform even by using a single mode laser beam in which a portion having a high light intensity exists in the beam center from the outer peripheral portion.

According to the invention described in claims 5 to 9, it is possible to provide a laser processing method using the above-mentioned laser processing apparatus, and in the invention described in claim 10, the object to be processed by such a laser processing method is provided. It is possible to provide a method for manufacturing an article having a laser-processed object, which includes a laser processing step of processing the object.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows the configuration of a laser processing apparatus according to a first embodiment of the present invention. This laser processing apparatus includes a cylindrical lens 11 and a lens holder 1 as a holding member for holding the cylindrical lens 11.
2 and a rotary power mechanism 13 as a means for rotating the lens holder 12.

The cylindrical lens 11 is made by cutting the outer periphery of a semi-cylindrical lens so as to have a circular shape when viewed from above, and is housed in the circular opening of the lens holder 12. . The lens holder 12 is provided with a gear on its outer side in the circumferential direction, and is rotated in the circumferential direction by the rotary power mechanism 13.

When performing laser processing using such a laser processing apparatus, first, a laser beam 14 emitted from a laser oscillator (not shown) is made incident on the cylindrical lens 11.
In this embodiment, the laser beam 14 is a multi-mode laser beam in which a portion having a high light intensity exists in the outer peripheral portion with respect to the beam center. The laser beam 14 incident on the cylindrical lens 11 becomes a linear focused beam 15 that is linearly focused.

Further, the lens holder 12 is rotated by the rotary power mechanism 13. Since the lens holder 12 has the same rotation axis as the propagation direction of the laser beam 14, the rotation of the lens holder 12 can rotate the linear focused beam 15 about the rotation axis. Then, the linear condensed beam 15 is rotated to irradiate the workpiece 1. As a result, the linear condensed beam 15 rotates on the workpiece 1 with the center point 16 of the line length as the center of rotation. FIG. 2 shows a state in which the lens holder 12 is rotated 90 degrees with respect to FIG.

In this way, by rotating the linear condensed beam 15 with the center point 16 of the line length as the center of rotation, the multi-mode of the multi-mode in which a portion having a high light intensity exists in the outer peripheral portion from the beam center. Even if a laser beam is used, the light intensity distribution can be made uniform.

When a thin film-deposited semiconductor substrate is used as the work piece 1 and heat treatment is performed through the thin film, the linear focused beam 15 is rotated at a speed sufficiently higher than the speed at which the semiconductor substrate is moved. For example, the heat distribution on the back surface (transmission side) of the thin film can be made flat. Furthermore, if the rotational speed of the lens holder 12 and the heat transfer of the thin film are controlled by the film thickness and the like, a smoother heat distribution can be obtained. (Second Embodiment) In the above-described first embodiment, a laser beam of a multi-mode in which a portion having a high light intensity exists in the outer peripheral portion from the beam center is shown as the laser beam, but this embodiment is not limited to this embodiment. In the configuration, a single-mode laser beam in which a portion having a high light intensity exists in the beam center from the outer peripheral portion is used to make the light intensity distribution uniform.

Therefore, in the laser processing apparatus according to the second embodiment, as shown in FIG. 3, the window 1 as a refracting member is provided on the laser beam incident side of the cylindrical surface lens 11.
7 is arranged to be inclined. The window 17 is held by the lens holder 12. Other configurations are similar to those of the first embodiment.

When laser processing is performed using such a laser processing apparatus, first, a window 1 for a single mode laser beam 14 emitted from a laser oscillator (not shown) is used.
It is incident on 7. The laser beam 14 incident on the window 17 is refracted by the window 17. The direction in which the laser beam is refracted by the window 17 and the cylindrical lens 11
Since the center line of curvature is in the same plane, when the lens holder 12 is rotated in the propagation direction by the rotary power mechanism 13 as in the first embodiment, the linear condensed beam 15 rotates. In this case, on the workpiece 1, the linear condensed beam 15 rotates with a position 17 decentered from the center point 16 of the line length serving as a rotation center.

By thus decentering the rotation center of the linear focused beam 15 from the center point of the line length, a single-mode laser beam in which a portion having a high light intensity exists in the beam center rather than in the outer peripheral portion is obtained. Even if it is used, the rotating circumference of the portion having a high light intensity increases, and the irradiation area of that portion eventually increases, so that the light intensity distribution can be made uniform.

Therefore, when a semiconductor substrate on which a thin film is vapor-deposited is used as the workpiece 1 and heat treatment is performed through the thin film,
Similar to the first embodiment, a smoother heat distribution can be obtained. (Third Embodiment) In the third embodiment, as in the second embodiment, the light intensity distribution is made uniform by using a single mode laser beam.

FIG. 4 shows the configuration of the laser processing apparatus according to the third embodiment. This laser processing apparatus is provided with a holed mirror 21 having a circular hole 21a at its center,
A wedge-shaped outer surface mirror 22, a wedge-shaped inner surface mirror 23, a mirror holder 24 as a holding member that fixes the wedge-shaped outer surface mirror 22 and the wedge-shaped inner surface mirror 23 and is provided with gears on the outer side in the circumferential direction, and a means for rotating the mirror holder 24. Rotation power mechanism 25, prism 26, and prism 2
6, a cylindrical surface lens 27 arranged on the transmission side of the lens 6, a lens holder 28 having the prism 26 and the cylindrical surface lens 27 fixed, and provided with gears on the outside in the circumferential direction, and rotational power as means for rotating the lens holder 28. And a mechanism 29.

Wedge-shaped outer surface mirror 22 and wedge-shaped inner surface mirror 23
Each has two mirror surfaces arranged in a wedge shape, and is installed so that the incident surfaces (surfaces including the incident beam and the reflected beam) of both the wedge-shaped outer surface mirror 22 and the wedge-shaped inner surface mirror 23 are precisely in the same plane. , Incident laser beam 30
Is configured to reflect in the vertical direction.

In the laser processing apparatus thus constructed, the single-mode laser beam emitted from the laser oscillator (not shown) passes through the hole 21a from the rear surface of the holed mirror 21 and enters the wedge-shaped outer surface mirror 22, This wedge-shaped outer surface mirror 22 divides it into two and reflects it in a direction perpendicular to the propagation direction. Then, it is folded back by the wedge-shaped inner surface mirror 23 in the direction opposite to the propagation direction, and reflected by the surface of the holed mirror 21 to become the two-divided laser beams 31a and 31b. The two-divided laser beams 31a and 31b are semicircular in cross section of the beams and face each other in opposite directions, as shown by hatched semicircles in the figure. In addition, in the above-mentioned structure, the mirror 21 with a hole is provided.
And the wedge-shaped outer surface mirror 22 and the wedge-shaped inner surface mirror 23,
A two-divided laser beam generation means for generating a two-divided laser beam is configured.

The two-divided laser beams 31a and 31b are incident on the apex of the prism 26 at the central optical axis. In this case, it is desirable that the two-divided laser beams 31a and 31b be incident in parallel to the surface perpendicular to the straight line formed at the apex of the prism 26. Then, due to refraction by the prism 26,
The transmitted polarized laser beams are superposed at a point on the central optical axis. At this time, the two split laser beams 31
Since a and 31b are superposed from the portion where the light intensity is weak, the combined intensity distribution changes one by one on an arbitrary central optical axis.

Further, by the cylindrical lens 27 arranged on the transmission side of the prism 26, a synthetic linear focused beam 15 having a flat light intensity distribution suitable for processing is obtained. In this case, assuming that the position of the workpiece 1 is immovable due to the focal length of the cylindrical surface lens 27, if the position of the apex of the wedge-shaped outer surface mirror 22 is adjusted with respect to the wedge-shaped inner surface mirror 23 along the propagation direction, The degree of overlap between the two laser beams can be controlled.

As described above, the laser beam 30 is divided into two so that the laser beam 30 has a semicircular cross section and faces each other in opposite directions to generate a two-divided laser beam. By deflecting the divided laser beam and converging the deflected two-divided laser beam into a linear shape, even if a single mode laser beam in which a portion having a high light intensity exists in the beam center from the outer peripheral portion,
The light intensity distribution can be made uniform.

Therefore, when a semiconductor substrate having a thin film deposited thereon is used as the workpiece 1 and heat treatment is performed through the thin film,
Similar to the first embodiment, a smoother heat distribution can be obtained.

Further, in this embodiment, when the synthetic linear focused beam obtained by the above method is rotated, the wedge-shaped outer surface mirror 22 and the wedge-shaped inner surface mirror 23 are fixed, and the prism. The lens holder 28 fixing the lens 26 and the cylindrical lens 27 is rotated by the rotation power mechanisms 25 and 29 in synchronization with the rotation speed. At this time, the mirror holder 24 and the lens holder 28 may be simultaneously rotated by using one rotation power mechanism. (Other Embodiments) In the above-described first to third embodiments, the cylindrical lens 27 is cut into a circular shape and housed in the circular opening of the lens holder 28.
Without cutting the semi-cylindrical cylindrical lens 27 into a circular shape,
The lens holder 28 may be stored as it is with a gap in the circular opening.

Further, in the above-mentioned first to third embodiments,
We have shown a semiconductor substrate with a thin film formed on the surface as the work piece, and laser processing for performing heat treatment through the thin film. Laser processing may be used for the opening processing. In the drilling process using such a laser, conventionally, an aperture is set during the propagation of the laser beam, and the aperture shape is reduced and image-projected, or a trepanning method using a galvanometer mirror device is used to form a minute circular beam. Is performed by starting in a circle or scanning in a spiral orbit. In the former method of imaging the aperture, not all laser beams pass through the aperture, so
Energy loss occurs, and a long beam propagation distance is necessary to realize the reduction ratio. Further, in the method using the galvano mirror device, the two mirrors are independently controlled with high accuracy in two axes orthogonal to each other to move the laser boom in a circular or spiral shape, and further the processing is performed in synchronization with the irradiation laser beam. Therefore, there is a problem that the control technology becomes complicated. On the other hand, if the laser processing according to the above-described first to third embodiments is used, it is possible to perform the drilling without causing energy loss and requiring complicated control.

The laser processing methods shown in the above-described various embodiments can be used as a laser processing step in a method for manufacturing an article having a laser-processed workpiece.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a state in which a lens holder 12 is rotated 90 degrees with respect to FIG.

FIG. 3 is a diagram showing a configuration of a laser processing apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a laser processing apparatus according to a third embodiment of the present invention.

FIG. 5 is a diagram for explaining a method of heat-treating a semiconductor substrate via a thin film thereof using a laser.

[Explanation of symbols]

11 ... Cylindrical surface lens, 12 ... Lens holder, 13 ... Rotation power mechanism, 17 ... Window, 21 ... Hole mirror,
22 ... Wedge-shaped outer surface mirror, 23 ... Wedge-shaped inner surface mirror, 24 ...
Mirror holder, 25 ... Rotating power mechanism, 26 ... Prism, 27 ... Cylindrical surface lens, 28 ... Lens holder, 29
… Rotation power mechanism.

Claims (10)

[Claims] 1. A laser beam is linearly focused to form a linear focused beam, and the linear focused beam is rotated about a rotation axis parallel to its propagation direction, and this rotation causes the light intensity distribution to change. A laser processing apparatus configured to irradiate a workpiece with a uniformized beam. 2. A cylindrical surface lens for linearly focusing the laser beam is provided, and by rotating the cylindrical surface lens, the center point of the line length of the linear focused beam becomes the center of rotation. The laser processing apparatus according to claim 1, wherein the linear focused beam is rotated. 3. A cylindrical lens that linearly collects the laser beam is provided, and a refracting member that refracts the laser beam and enters the cylindrical lens is disposed on the incident side of the cylindrical lens. By rotating the cylindrical lens and the refracting member, the linear condensed beam is rotated with a position eccentric from the center point of the line length of the linear condensed beam serving as a rotation center. The laser processing apparatus according to claim 1, wherein the laser processing apparatus is a laser processing apparatus. 4. A laser beam is divided into two so as to face each other in a semicircular shape in a cross section in a direction opposite to each other to generate a two-divided laser beam, and the two-divided laser beam is superposed on the two-divided laser beam. A laser processing apparatus configured to deflect a beam, collect the deflected two-divided laser beam into a linear shape, and obtain a linear focused beam for irradiating a workpiece. 5. The laser processing apparatus according to claim 4, wherein the linear condensed beam is rotated with a center point of a line length of the linear condensed beam as a rotation center. 6. A linearly focused beam is formed by linearly focusing a laser beam having a light intensity distribution in which a portion having a high light intensity is present in the outer peripheral portion from the center of the beam, and the line length of the linearly focused beam. A laser processing method, wherein the linearly focused beam is rotated about the center point of, and the rotated linearly focused beam is applied to the workpiece. 7. A linearly focused beam is formed by linearly focusing a laser beam having a light intensity distribution in which a portion having a high light intensity exists in the beam center from the outer peripheral portion, and the line length of the linear focused beam. A laser processing method characterized in that the linear focused beam is rotated about a position eccentric from the center point of, and the rotated linear focused beam is applied to the workpiece. 8. A laser beam having a light intensity distribution in which a portion having a high light intensity is present in the beam center from the outer peripheral portion is divided into two so as to face each other in a semicircular shape in a cross section in opposite directions,
A two-divided laser beam is generated, the two-divided laser beam is deflected so that the two-divided laser beam is superposed, and the deflected two-divided laser beam is condensed linearly and irradiated to a workpiece. Characteristic laser processing method. 9. The laser according to claim 8, wherein the linear condensed beam is rotated around a center point of a line length of the linear condensed beam to irradiate the workpiece. Processing method. 10. A method of manufacturing an article having a laser-processed workpiece, comprising a laser processing step of processing the workpiece by the laser processing method according to claim 6. A method for manufacturing an article having a laser-processed object, comprising: