JP2008113026A - Method of forming laser light beam, and laser crystallization apparatus for crystallizing thin-film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily shape the beam shape of laser light with reliability. <P>SOLUTION: In a method of shaping a laser light beam, laser light emitted from a laser light source is shaped in two or more directions through a plurality of homogenizers which include a plurality of cylindrical lenses and have different shaping directions. In this method, a side of a rectangular beam incident on the homogenizers is inclined so as to have an angle difference of 1° to 89° with respect to the main cut surface directions of the cylindrical lenses, so that the laser light beam passing through the homogenizers is shaped. Thus it is possible to easily and reliably shape the laser light beam having passed through the homogenizers and apply this method to the manufacturing of a high-quality crystallized thin film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable for an apparatus using a laser beam used for material processing, surface modification, etc., and a method for shaping the beam shape of the laser beam into a desired shape and the laser beam shaped by the shaping method. The present invention relates to a laser beam thin film crystallization apparatus using

  Conventionally, a method using a homogenizer is known as a method of shaping laser light. For example, in the apparatus shown in FIG. 5, the laser light 2 generated from the laser light source 1 is not interrupted in the middle, passes through mirrors 4a and 4b, and a telescope lens 4c, and is a homogenizer 5 composed of a plurality of cylindrical lenses. 6 is incident. At this time, the laser beam 2 is incident so that the optical axis 3 thereof is parallel to the lens axis 8 of the homogenizers 5 and 6. The laser beam 2 that has passed through the homogenizers 5 and 6 is emitted from a cylindrical large lens 7 that constitutes a part of the homogenizer 6 and is larger than the beam, and is applied to a sample surface 9 (an irradiated thin film or the like) at the focal position of the lens 7. Irradiated.

  When the laser beam 2 passes through the homogenizers 5 and 6, the beam shape is shaped. The homogenizers 5 and 6 have a typical structure, and a detailed structure thereof will be described with reference to FIG. The homogenizer is composed of a lens group 14 and a lens group 15 including cylindrical small lenses 10... 10 smaller than the beam, and a large cylindrical lens 7 larger than the beam. This homogenizer divides the Gaussian-shaped laser light intensity distribution shown in FIG. 7A into a plurality of beams 11... 11 by the homogenizer lens group 14, and then the sample surface 9 at the focal position of the cylindrical large lens 7. A plurality of beams 11... 11 are recombined to obtain a linear beam shape. The homogenizer can obtain a linear beam shape only by the lens group 14, but the distance between the lens group 14 and the lens group 15 can be changed by installing the lens group 15 having the same number as the lens group 14. A method of changing the beam shape can also be adopted.

The homogenizers 5 and 6 have the same structure, but the shaping directions are different from each other by changing the arrangement direction thereof, and the beam is shaped in two orthogonal directions. Generally, the direction of shaping differs by 90 degrees.
As a result, the beam shape of the laser light applied to the sample surface 9 has the uniform portion 12 and the inclined portion 13 as shown in FIG. 7B, and the uniform portion 12 is linear. ing. The laser beam whose beam shape is shaped is irradiated on a sample such as plastic placed on the sample surface, and is used for processing the sample, crystallization of a sample made of amorphous Si, and the like.

The laser beam shaped by the above method has a beam shape in which the uniform part is linear and parallel as described above, but in recent years, various types of research have used laser beam with deformed beam shape. It has been found that better results may be obtained. For example, Patent Document 1 proposes the use of laser light in which the energy distribution of the beam is inclined when crystallizing a thin film using laser light, and Non-Patent Document 1 proposes the use of a Gaussian-shaped beam. Examples of use are described.
According to the above publication, crystallization of a thin film can be shifted from a higher energy to a lower energy by using a laser beam having an inclined beam, and the energy irradiated at the end of the sample is set to a certain value or less. It is said that a crystallized thin film with good performance can be obtained.
Japanese Patent Laid-Open No. 10-64815 FPD Intelligence, May 1999, page 77

  However, a method for easily and reliably obtaining the beam shape as described above has not been proposed, and therefore, it is not possible to effectively obtain the effect of irradiation with laser light having a shaped beam shape.

  The present invention has been made against the background of the above circumstances, and a laser light beam shaping method capable of easily and surely shaping the beam shape of the laser light into a desired shape, and a laser light thin film using the shaping method. An object is to provide a crystallization apparatus.

  In order to solve the above-mentioned problems, the laser beam shaping method according to the first aspect of the present invention comprises a plurality of cylindrical lenses for shaping the laser beam emitted from the laser light source, and the shaping directions are individually different. In the laser beam shaping method for shaping in two or more directions through the homogenizer, one side of the square beam incident on the homogenizer has an angle difference of 1 to 89 degrees with respect to the main cut surface direction of the cylindrical lens. The beam of laser light passing through the homogenizer is shaped by inclining it so that it is incident on the homogenizer.

  A laser light beam shaping method according to a second aspect of the invention is the laser light beam shaping method according to the first aspect of the invention, wherein the telescope lens in the optical path between the laser light source and the cylindrical lens is centered on the optical axis direction. The laser beam incident on the homogenizer is tilted in the rotation direction.

  A laser light thin film crystallization apparatus according to a third aspect of the present invention includes a laser light source for irradiating a thin film to be irradiated with laser light to cause crystallization, a telescope lens, and a homogenizer lens. The laser light beam incident on the homogenizer is inclined with respect to the optical axis so as to be inclined with respect to the direction of the main cutting surface of the homogenizer cylindrical lens.

The present invention is suitable for applications in which a thin film is irradiated with laser light to be crystallized or modified. However, the present invention is not limited to these applications, and various applications for irradiating an irradiated object with laser light. It is possible to apply to.
The purpose of shaping varies depending on the purpose of laser irradiation, etc., and the beam shape to be obtained also differs, but the inclination and shape of the inclined part in the beam shape are changed, the uniform part is inclined, or it is changed to a curved surface. And shaping to change the curvature of the curved surface, or to reduce the inclination of the inclined uniform part.

The shaping method of the present invention is a method in which laser light is incident on the homogenizer in a state shifted in the rotational direction about the optical axis. Usually, when laser light is incident on a homogenizer, the side of the beam is set along the main cutting surface (curvature direction) of the cylindrical lens. In the present invention, this is given an angular difference. That is, in a rectangular beam, one side of the beam is incident so as to have an angular difference with respect to the direction of the main cut surface (curvature direction) of the cylindrical lens.
The tilt angle can be arbitrarily selected within a range of 1 to 89 degrees. For example, the tilt angle is determined in consideration of the beam shape before shaping, the beam shape after shaping, the structure of the homogenizer, and the like.

In order for the laser light to enter the homogenizer in an inclined state, the positional relationship between the laser light source and the homogenizer may be determined so that the laser light emitted from the laser light source is inclined with respect to the homogenizer. In addition, an optical member or the like that tilts the laser beam between the laser light source and the homogenizer may be installed. This optical member may be particularly installed for the purpose of giving an inclination, or may utilize an optical member originally incorporated in the laser irradiation apparatus. For example, by placing the telescope originally installed between the laser light source and the homogenizer in a state of being tilted (rotated) in the rotation direction with the optical axis as the central axis, the telescope is placed against the homogenizer in the optical axis direction. The laser beam can be tilted.
According to this method, a beam shape in which the uniform portion is shaped into a convex shape can be obtained. Although the detailed principle is not clear, the inventor understands as follows. That is, if the beam incident on the homogenizer is inclined, the beam position on the irradiation surface is different because the conditions (position and angle) incident on the homogenizer are different, and therefore the beam shape in irradiation becomes a convex shape.

The beam shape can be easily shaped by the above method.
Furthermore, it has been confirmed that the most effective laser beam irradiation in thin-film crystallization is that the laser beam does not have a simple rectangular beam shape, but a modified uniform shape is effective. However, in the laser beam thinning apparatus of the present invention, the desired beam shape can be obtained reliably and easily by shaping, so that the irradiation effect of the laser beam having the shaped beam shape is reliably and efficiently obtained in thin film crystallization. can get.
Of course, the shaping method of the present invention is not limited to thin film crystallization as described above.

  As described above, according to the laser light beam shaping method of the present invention, the optical path length between cylindrical lenses in one or more homogenizers is set to a part or all of the cylindrical lenses. The laser beam is made to enter the homogenizer while being tilted so as to have an angle difference of 1 to 89 degrees with respect to the main cutting plane direction of the cylindrical lens, or the focal position by the homogenizer and the irradiated object Therefore, the beam shape of the laser beam which is divided by the homogenizer and then combined on the irradiated surface is changed to a desired shape. As a result, a desired beam shape can be obtained easily and reliably, and the action of the shaped laser beam can be efficiently obtained by using it for crystallization of a thin film. Further, in addition to the above method, if a part of the laser light is shielded or attenuated between the laser light source and the irradiated object, the beam can be shaped more extensively.

(Embodiment 1)
Embodiments of the present invention will be described below with reference to the accompanying drawings. In each embodiment, the laser light irradiation apparatus shown in FIG. 5 has a basic structure.
In the first embodiment, when the laser beam 2 is incident on the homogenizers 5 and 6 as shown in FIG. 1, for example, by tilting the telescope 4c shown in FIG. 6 has a predetermined angular difference from the direction of the main cut surface of the cylindrical small lens 10.
As shown in FIG. 2, the tilt position and angle of the laser light are changed by tilt incidence on the homogenizer, and the width and position of the split light 11a are changed. By combining the split light 11a at the sample surface 9, as shown in FIG. 3, a beam shape in which the uniform portion becomes the convex portion 12b is obtained.

  The apparatus of the above-described embodiment can be used as a laser beam thin film crystallization apparatus in which a thin film is disposed on the sample surface and the thin film is crystallized by irradiating the thin film with the shaped laser beam. .

Using a laser beam having a beam shape of 308 nm and 40 × 15 mm generated by an excimer laser, the beam shape was shaped by the homogenizer optical system in the above embodiment.
As shown in FIG. 5, the laser light 2 generated from the laser light source 1 passes through the telescope lens 4c and then passes through two homogenizers having different directions. However, the beam shape is shaped by each shaping method, and the sample surface 9 The desired beam shape was obtained. The beam shape was measured by installing a CCD camera at the position of the sample surface.

Similarly to the first embodiment, the telescope 4c is tilted by 2 degrees with respect to the optical axis, and the laser beam incident on the homogenizer 5 is tilted by 2 degrees. As a result, as shown in FIG. 4, a beam shape in which the uniform portion became a smooth convex shape was obtained on the sample surface.

It is the schematic which shows one Embodiment of this invention. It is the schematic which shows other embodiment similarly. It is a figure which shows the beam shape after the shaping similarly obtained by this embodiment. It is a figure which shows the beam shape after shaping similarly obtained by the other Example. It is the schematic which shows the main structures of the conventional laser irradiation apparatus provided with the homogenizer. It is a graph which similarly shows the detailed structure of a homogenizer. It is a figure which shows the beam shape before the homogenizer injection similarly obtained by the conventional homogenizer, and the beam shape shape | molded by the homogenizer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Laser light 3 Optical axis 4c Telescope 5 Homogenizer 6 Homogenizer 7 Cylindrical large lens 8 Lens axis 10 Cylindrical small lens 11 Beam 11a Split light 12 Uniform part 13 Inclination part 12b Convex part 14 Lens group 15 Lens group

Claims (3)

In the method of shaping a laser light beam that is shaped in two or more directions through a plurality of homogenizers having different cylindrical shaping directions, the laser light emitted from a laser light source is formed in a rectangular shape incident on the homogenizer. A beam of laser light passing through the homogenizer is shaped by tilting one side of the beam so as to have an angle difference of 1 to 89 degrees with respect to the main cutting plane direction of the cylindrical lens and entering the homogenizer. A laser beam shaping method characterized by the above. 2. The laser beam according to claim 1, wherein the telescope lens in the optical path between the laser light source and the cylindrical lens is tilted in a rotation direction with the optical axis direction as a central axis, and the laser beam incident on the homogenizer is tilted. Beam shaping method. A laser light source for irradiating a thin film to be irradiated with a laser beam for crystallization, a telescope lens, and a homogenizer lens. The telescope lens is a cylindrical lens in which a laser beam incident on the homogenizer is a homogenizer. A laser beam thin film crystallization apparatus, wherein the laser beam thin film crystallization apparatus is disposed so as to be inclined with respect to a main cutting plane direction so as to be inclined in a rotation direction having an optical axis direction as a central axis.

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