KR101335639B1 - Laser crystallization apparatus and silicon crystallization method using the same - Google Patents

Abstract

The present invention provides a laser crystallization apparatus and a silicon crystallization method using the same. The laser crystallization apparatus according to the present invention includes a laser irradiation apparatus for irradiating a laser, a stage disposed corresponding to the laser irradiation apparatus and inclined at an inclination angle, and a plurality of pins mounted on the stage and moving up and down.

Laser Crystallizer, Stage, Amorphous Silicon Film, Polysilicon Film

Description

LASER CRYSTALLIZATION APPARATUS AND SILICON CRYSTALLIZATION METHOD USING THE SAME

1 is a view showing a laser crystallization apparatus according to an embodiment of the present invention.

2A to 2C are diagrams for describing a silicon crystallization method using a laser crystallization apparatus according to an embodiment of the present invention.

3 is a view showing a shortening of the laser beam delivered to the substrate in the silicon crystallization method according to an embodiment of the present invention.

4 is a view showing the laser intensity distribution according to the uniaxial superposition of the laser beam delivered to the substrate in the silicon crystallization method according to an embodiment of the present invention.

The present invention relates to a silicon crystallization technology, and more particularly, to a laser crystallization apparatus and a silicon crystallization method using the same.

Display devices such as an organic light emitting display device and a liquid crystal display device are widely used as next generation display devices because they have a thin thickness and operate at a low voltage, unlike a cathode ray tube requiring a large volume and a high voltage.

In particular, the organic light emitting diode display recombines electrons and holes injected through an anode and a cathode into an organic material to form excitons, and energy of a specific wavelength is formed by energy from the excitons formed. It is a self-luminous display device using a phenomenon in which light is generated.

Therefore, the organic light emitting diode display is attracting attention as a next-generation display device because it does not require a separate light source such as a backlight, and thus has low power consumption and easy securing of a wide viewing angle and a fast response speed compared to the liquid crystal display.

The organic light emitting diode display is classified into a passive matrix type and an active matrix type according to a driving method, and recently, low power consumption, high definition, fast response speed, wide viewing angle, and thinness can be realized. Active drive type is mainly applied.

In an active driven organic light emitting display device, pixels, which are basic units of image representation, are arranged in a matrix on a substrate, and red (R), green (G), and blue (B) are arranged for each pixel. A light emitting device in which a first electrode of an anode and a second electrode of a cathode are sequentially formed is disposed with a light emitting layer made of each organic material emitting light. Each pixel is connected to a light emitting element to form a thin film transistor (TFT, hereinafter referred to as TFT) to independently control the pixel.

In addition, since the substrate on which the pixel is formed of the organic light emitting diode display is mainly made of an insulating material such as glass or plastic, it is important to manufacture a TFT having favorable characteristics for pixel operation without causing deformation of the substrate.

Therefore, the organic light emitting diode display uses a polysilicon TFT which deposits amorphous silicon and crystallizes it at low temperature as an active layer, and mainly uses excimer laser annealing as a crystallization process. Laser crystallization processes such as excimer laser annealing (ELA) are applied.

In the laser crystallization process, a laser beam having a high energy is irradiated to an amorphous silicon film in a portion where crystallization is required. Since crystallization is performed by instantaneous heating, crystallization can be performed without deforming the substrate. In addition, when the amorphous silicon film is melted in a liquid state by the laser beam and solidified into a solid, the silicon atoms are rearranged into grains having excellent crystallinity, thereby ensuring excellent electrical characteristics of the polysilicon film.

Meanwhile, in the laser crystallization process, the laser beam is incident perpendicularly to the substrate and is concentrated and irradiated in a narrow area. Therefore, in order to irradiate a laser onto the entire substrate, the substrate on which the amorphous silicon film is deposited is mounted on the stage of the laser crystallization apparatus, and then the laser beam is irradiated to the amorphous silicon film of the predetermined area, and the stage is moved again to move the amorphous silicon film of the next area. The process of irradiating the laser beam must be repeated.

However, when the laser beam is incident perpendicularly to the substrate, the short axis length of the laser beam is short, so that the effective number of effective laser pulses irradiated to the same point of the substrate when the laser beam is irradiated to the amorphous silicon film of the same area while moving the substrate is small. However, the uniformity between the laser shots is poor and the crystallization characteristics are lowered. As a result, streaks and the like are severely generated in the polysilicon film.

The present invention is to solve the problems of the prior art as described above, an object of the present invention is to improve the crystallization characteristics when crystallizing silicon laser crystallization apparatus that can minimize the generation of streaks in the polysilicon film and the same It is to provide a silicon crystallization method used.

In order to achieve the above object, the laser crystallization apparatus according to the embodiment of the present invention, a laser irradiation apparatus for irradiating a laser, a stage disposed corresponding to the laser irradiation apparatus and inclined with an inclination angle, and mounted on the stage, It includes a plurality of moving pins.

Here, the inclination angle of the stage may have an angle of 0 to 90 degrees.

In addition, the laser irradiation apparatus generates a laser beam generating a laser beam, a plurality of reflectors for changing the traveling direction of the laser beam emitted through the laser generating unit, and the energy density of the laser beam whose traveling direction is changed from the reflecting mirrors is uniform. It may contain a shortening homogenizer.

In order to achieve the above object, in the silicon crystallization method according to the embodiment of the present invention, the laser crystallization apparatus described above is prepared, and a substrate on which an amorphous silicon film is stacked is introduced into the laser crystallization apparatus. The pins are then raised to support the substrate horizontally, and the pins are lowered sequentially to tilt the substrate at the same tilt angle as the stage. Thereafter, the pins are sequentially lowered again to seat the substrate on the stage in an inclined state, and the laser beam is generated from the laser irradiation apparatus to irradiate the laser beam with an amorphous silicon film laminated to the substrate.

Here, the laser beam may have an energy of 250 to 500mJ / cm 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

First, a silicon crystallization apparatus according to an embodiment of the present invention will be described with reference to FIG. 1.

Referring to FIG. 1, a laser crystallization apparatus includes a laser irradiation apparatus 100 for irradiating a laser, a stage 130 disposed corresponding to the laser irradiation apparatus 100 and inclined with an inclination angle Θ, and a stage 130. It includes a plurality of pins 140 mounted on the) to move up and down.

The laser irradiation apparatus 100 may include a laser generator 110 that generates a laser beam, and first, second, and third reflectors 121 and 122 that change a traveling direction of the laser beam emitted through the laser generator 110. , 123, and a uniaxial homogenizer 124 uniforming the energy density of the laser beam whose direction of travel is changed from the third reflector 123.

In addition, the inclination angle Θ of the stage 130 is greater than 0 degrees and greater than 90 degrees so that the substrate 150 (see FIG. 2A) is seated on the stage 130 so that the laser beam is not vertically incident when the laser beam is irradiated. It may have a small angle, preferably between 30 and 45 degrees.

Next, the silicon crystallization method using the laser device described above with reference to FIGS. 2A to 2C will be described.

Referring to FIG. 2A, the substrate 150 in which the amorphous silicon film 151 is stacked is introduced into the laser crystallization apparatus described above, and the pins 140 are raised to support the substrate 150 horizontally.

Next, as shown in FIG. 2B, the fins 140 are sequentially lowered to tilt the substrate 150 at the same tilt angle Θ as the stage 130.

Next, as shown in FIG. 2C, the pins 140 are sequentially lowered again to seat the substrate 150 on the stage 130 in an inclined state. In this case, since the pins 140 are lowered and the substrate 150 is automatically aligned with the stage 130, a separate process for aligning the substrate 150 with the stage 130 is not required.

Thereafter, the laser beam is generated from the laser irradiation apparatus 100 at an energy of 250 to 500 mJ / cm 2, preferably 315 mJ / cm 2, thereby irradiating the laser beam to the amorphous silicon film 151 laminated on the substrate 150. The silicon film 151 is changed into a polysilicon film (not shown).

  Then, as the substrate 150 is seated on the stage 150 with the same inclination angle Θ as the stage 130, the short axis length of the laser beam transmitted to the substrate 150 as shown in FIG. 3 is increased. This increases compared to the case where the horizontal position.

In addition, the point A of the substrate 150 is the focus area of the laser beam is irradiated with the laser energy of the above-described range, the point B is a point away from the focus area, and the laser beam at a lower energy of about 5 mJ / cm 2 than the point A This is investigated. As a result, the number of effective laser pulses irradiated to the same point of the substrate 150 is increased by overlapping the laser beams irradiated onto the substrate 150 with the distribution as shown in FIG. 4, and the uniformity between laser shots is improved. As a result, generation of streaks and the like on the polysilicon film can be minimized.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

As described above, the laser crystallization apparatus according to the exemplary embodiment of the present invention includes a stage having an inclination angle, and thus the uniformity between the effective laser pulses and the laser shots irradiated to the same point of the substrate is set by mounting the substrate on the stage with the inclination angle. can do.

Therefore, when the silicon film is crystallized using the laser crystallization device, streaks or the like caused by the polysilicon film can be minimized.

Claims (5)

A laser irradiation device for irradiating a laser; A stage disposed corresponding to the laser irradiation apparatus and inclined at an inclination angle; And A plurality of pins mounted on the stage to support the substrate horizontally and sequentially descend to tilt the substrate in the tilted state. Laser crystallization apparatus comprising a. The method according to claim 1, And a tilt angle of the stage is 0 to 90 degrees. The method according to claim 1, The laser irradiation device A laser generator for generating a laser beam, A reflector for changing a traveling direction of the laser beam emitted through the laser generator; And a uniaxial homogenizer for uniforming the energy density of the laser beam whose direction of travel is changed from the reflector. Preparing a laser crystallization apparatus according to any one of claims 1 to 3; Inputting a substrate on which an amorphous silicon film is stacked into the laser crystallization apparatus; Lifting the pins to horizontally support the substrate; Sequentially lowering the pins to tilt the substrate at the same tilt angle as the stage; Lowering the pins sequentially again to seat the substrate on the stage in an inclined state; And Irradiating a laser beam to the amorphous silicon film laminated on the substrate by generating a laser beam from the laser irradiation device. 5. The method of claim 4, Silicon crystallization method wherein the laser beam has an energy of 250 to 500mJ / ㎠.

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