JP2002359208A - Laser annealing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser annealing apparatus having a simple constitution and featuring easy optical-axis adjustment. SOLUTION: This laser annealing apparatus comprises a first lens 13 that converges the laser beam 12 emitted from a laser device 11, an optical fiber 14 consisting of a multi-mode optical fiber, a second lens 15 that expands the laser beam 12 radiated from the optical fiber 14 to a specified size, an optical fiber bundle 16 which consists of a plurality of multi-mode optical fibers each having a plane of incidence and a plane of radiance, and a cylindrical lens 18 that radiates the laser beam 12 which radiates from the optical fiber bundle 16, by converging the beam only in the minor-axis direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser annealing apparatus used for forming a polycrystalline silicon thin film for a thin film transistor (TFT) at a low temperature.

[0002]

2. Description of the Related Art In recent years, a semiconductor device having a thin film transistor on an insulating substrate such as glass, for example, an active liquid crystal display device using the thin film transistor for driving pixels has been developed. Generally, a thin film silicon semiconductor is used as a thin film transistor used in such an apparatus.

Some thin-film silicon semiconductors are made of polycrystalline silicon having crystallinity. This polycrystalline silicon thin film transistor has advantages such as an electron mobility of two orders of magnitude or more as compared with an amorphous silicon thin film transistor, miniaturization of elements and integration of a drive circuit on the same substrate.

In the field of liquid crystal display devices, there has been active development of a technique for manufacturing a thin film transistor array with a built-in driving circuit using a polycrystalline silicon thin film transistor on a glass substrate which is inexpensive and easy to increase in area. Practical use has begun. As a technique for forming a high-quality polycrystalline silicon thin film at a low temperature on a large-area substrate, a low-temperature crystallization method using an excimer laser is usually used.

A conventional laser annealing apparatus for producing a low-temperature polycrystalline silicon thin film will be briefly described. Note that an excimer laser is used as a laser device.

[0006] A beam expander comprising a cylindrical lens enlarges the beam diameter of a laser beam emitted from an excimer laser to suppress the beam spread. Note that two beam expanders, one for the vertical direction and one for the horizontal direction, are used, and a rectangular beam is formed by changing the magnification in the vertical direction and the horizontal direction.

[0007] The intensity distribution of the laser beam emitted from the beam expander is made uniform using a plurality of homogenizers each having an array of lenses, and then the laser beam is condensed only in the short-axis direction of the beam to form a linear beam. Is irradiated on the substrate to form a polycrystalline silicon thin film.

[0008]

However, in the above-mentioned conventional laser annealing apparatus, the number of optical components is large and the configuration is complicated, so that the optical axis of the optical system is likely to be shifted due to ambient temperature fluctuation, vibration and impact. , The beam intensity distribution tends to be non-uniform. In addition, there is a problem that skill is required for optical axis adjustment.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a laser annealing apparatus having a reduced number of optical components, a simple configuration, and easy optical axis adjustment. And

[0010]

According to a first aspect of the present invention, there is provided a laser annealing apparatus for emitting a laser beam, and a laser apparatus for shaping the laser beam and irradiating the laser beam on a substrate. A laser beam shaping device for forming a polycrystalline silicon thin film, wherein the laser beam shaping device comprises: an optical fiber comprising one multi-mode optical fiber;
And an optical fiber bundle comprising a plurality of multimode optical fibers having an emission surface. As a result, there are fewer optical components than before,
The configuration is simplified, and there is no deviation in adjustment due to ambient temperature fluctuation, vibration, or impact, thereby improving maintainability.

A laser annealing apparatus according to a second aspect of the present invention is the laser annealing apparatus according to the first aspect,
The optical fiber bundle is formed by bundling the plurality of multi-mode optical fibers so that the incident surface forms the same shape as the shape of the laser beam emitted from the laser device, and has a linear emission surface. Are formed by arranging the plurality of multimode optical fibers on a straight line. Thereby, the laser beam can be emitted linearly with a simple configuration.

A laser annealing apparatus according to a third aspect of the present invention is the laser annealing apparatus according to the first or second aspect, wherein the first lens for condensing the laser beam emitted from the laser apparatus; A second lens for expanding a laser beam emitted from the optical fiber to a predetermined size. Thereby, the number of optical components is small, the configuration is simple, and
It is possible to realize a laser annealing apparatus that can easily adjust the optical axis.

A laser annealing apparatus according to a fourth aspect of the present invention is the laser annealing apparatus according to any one of the first to third aspects, wherein the laser beam emitted from the optical fiber bundle is emitted only in the short axis direction. A third lens for condensing light is provided. Thereby, a linear laser beam having a uniform intensity distribution can be obtained more stably.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiment described here is merely an example, and the present invention is not necessarily limited to this.

(Embodiment 1) Hereinafter, Embodiment 1
Will be described. FIG.
1 is a schematic configuration diagram of a laser annealing device according to a first embodiment.

In FIG. 1, reference numeral 11 denotes a laser device;
A laser beam 12 is emitted. Reference numeral 13 denotes a first lens which collects the laser beam 12 emitted from the laser device 11. Reference numeral 14 denotes an optical fiber, which is formed of one multimode optical fiber and makes the intensity distribution of the laser beam 12 uniform. Reference numeral 15 denotes a second lens, which enlarges the laser beam 12 emitted from the optical fiber 14 to a predetermined size. Here, it is assumed that the laser beam 12 is enlarged to a size corresponding to the core diameter of the multimode optical fiber 20 constituting the optical fiber bundle 16. Reference numeral 16 denotes an optical fiber bundle, which includes a plurality of multimode optical fibers 20 each having an incident surface and an output surface. The core diameter of the multimode optical fibers constituting the optical fiber bundle 16 is smaller than the core diameter of the multimode optical fibers constituting the optical fiber 14. 17 is a substrate. 18
Denotes a third lens, which condenses the laser beam 12 emitted from the optical fiber bundle 16 only in the short axis direction and emits it.

Here, the optical fiber bundle 16 will be described with reference to FIG. This optical fiber bundle 16
Is formed by bundling a plurality of multimode optical fibers so that the incident surface 21 has the same shape as the shape of the laser beam 12 emitted from the laser device 11, as shown in FIG. As shown in FIG. 2 (b), a plurality of multimode optical fibers are formed on a straight line so as to form a linear exit surface 22. If you do this,
A linear laser beam can be easily obtained by using a multimode optical fiber.

Next, the operation of the laser annealing apparatus having the above configuration will be described. Here, a case where a cylindrical lens is used as the third lens will be described.

A laser beam 12 emitted from a laser device 11 is condensed by a first lens 13 and is incident on an optical fiber 14. Then, the laser beam 12 whose intensity distribution has been made uniform by the mode coupling in the optical fiber 14 is incident on the optical fiber bundle 16 via the second lens 15.

The optical fiber bundle 16 makes the shape of the incident laser beam 12 linear and emits it to the cylindrical lens 18. The cylindrical lens 18 focuses and irradiates the linear laser beam 12 emitted from the optical fiber bundle 16 only in the short axis direction,
A polycrystalline silicon thin film is formed thereon.

In the laser annealing apparatus according to the first embodiment, the first lens 13 for condensing the laser beam 12 emitted from the laser device 11, the optical fiber 14 composed of one multimode optical fiber, Optical fiber 1
A second lens 15 for expanding the laser beam 12 emitted from the optical fiber 4 to a predetermined size, an optical fiber bundle 16 composed of a plurality of multimode optical fibers having an entrance surface and an exit surface, and an optical fiber bundle 16. And a cylindrical lens 18 for condensing the emitted laser beam 12 only in the short axis direction and emitting the laser beam 12. Thus, the number of optical components is smaller than in the related art, the configuration is simple, and the mechanical stability is improved. Thus, a laser annealing apparatus capable of emitting a laser beam having a linear and uniform intensity distribution can be realized.

[0022]

According to the laser annealing apparatus according to the first aspect of the present invention, a laser apparatus for emitting a laser beam, and the laser beam is shaped and irradiated on a substrate to form a polycrystalline silicon thin film. A laser beam shaping device,
A laser annealing apparatus comprising: an optical fiber comprising one multi-mode optical fiber; an optical fiber bundle comprising a plurality of multi-mode optical fibers having an incident surface and an exit surface; , The number of optical components is smaller than that of the related art, the configuration is simplified, and there is no deviation in adjustment due to ambient temperature fluctuation, vibration, or impact, thereby improving maintainability.

According to the laser annealing apparatus according to the second aspect of the present invention, in the laser annealing apparatus according to the first aspect, the optical fiber bundle has an incident surface of a laser beam emitted from the laser apparatus. It is formed by bundling the plurality of multimode optical fibers so as to form the same shape as the shape, and formed by aligning the plurality of multimode optical fibers on a straight line so as to form a linear emission surface. Thus, the laser beam can be emitted linearly with a simple configuration.

According to the laser annealing apparatus of the third aspect of the present invention, in the laser annealing apparatus of the first or second aspect, the first apparatus for condensing a laser beam emitted from the laser apparatus. Since the lens and the second lens for expanding the laser beam emitted from the optical fiber to a predetermined size are provided, the number of optical components is small, the configuration is simple, and the optical axis adjustment is easy. It is possible to realize a simple laser annealing apparatus.

According to a laser annealing apparatus according to a fourth aspect of the present invention, in the laser annealing apparatus according to any one of the first to third aspects, the laser beam emitted from the optical fiber bundle has a short axis. By providing the third lens that condenses light only in the direction, a linear laser beam having a uniform intensity distribution can be obtained more stably.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a laser annealing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an entrance surface and an exit surface of the optical fiber bundle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Laser apparatus 12 Laser beam 13 1st lens 14 Optical fiber 15 2nd lens 16 Optical fiber bundle 17 Substrate 18 Cylindrical lens

Claims (4)

[Claims] A laser device for emitting a laser beam;
A laser beam shaping device comprising: a laser beam shaping device for shaping the laser beam onto a substrate to form a polycrystalline silicon thin film, wherein the laser beam shaping device comprises one multimode optical fiber. A laser annealing device comprising: an optical fiber; and an optical fiber bundle including a plurality of multi-mode optical fibers and having an input surface and an output surface. 2. The laser annealing apparatus according to claim 1, wherein the optical fiber bundle has a plurality of multi-mode light beams whose incident surface has the same shape as a shape of a laser beam emitted from the laser device. A laser annealing apparatus comprising: a bundle of fibers; and a plurality of the multimode optical fibers arranged in a straight line so as to form a linear emission surface. 3. The laser annealing apparatus according to claim 1, wherein a first lens for condensing a laser beam emitted from the laser apparatus, and a laser beam emitted from the optical fiber are provided. And a second lens that expands to a size of (a). 4. The laser annealing apparatus according to claim 1, further comprising a third lens that focuses a laser beam emitted from the optical fiber bundle only in a short axis direction. A laser annealing apparatus characterized by the above-mentioned.