Laser induced thermal imaging apparatus and laser induced thermal imaging method

This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0080338 filed on Aug. 30, 2005, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.

1. Field of the Invention

The present invention relates to a laser induced thermal imaging (LITI) apparatus and a laser induced thermal imaging method, and more specifically to a laser induced thermal imaging apparatus and a laser induced thermal imaging method for closely adhering a donor film to a substrate using an adhesion frame including an electromagnet and a substrate stage having an electromagnet and performing a laser induced thermal imaging process.

2. Discussion of Related Art

Generally, in an organic light emitting diode, an anode electrode, which is a lower electrode, is formed on an insulating substrate, an organic thin-film layer is formed on the anode electrode, and a cathode electrode, which is an upper electrode, is formed on the organic thin-film layer. The organic thin-film layer includes at least one of a hole injecting layer, a hole transport layer, an emission layer, a hole suppression layer, an electron transport layer or an electron injecting layer.

A method for forming the organic thin-film layer includes a deposition method and a lithographic method. The deposition method, which is a method for forming an organic light-emitting layer by vacuum depositing organic luminescent materials using a shadow mask, has problems in that it is difficult to form a micro-pattern, and also to apply to a large-size display device due to deformation of the mask. The lithographic method, which is a method for forming an organic light-emitting layer by depositing organic luminescent materials, followed by patterning them using a photoresist, may form a pattern having a fine pitch, but has a problem in that the properties of the organic light-emitting layer are deteriorated by a developing solution for forming a photoresist pattern or an etching solution of the organic luminescent materials.

In order to solve the problems described above, there has been proposed a method for directly pattering an organic light-emitting layer. An ink jet method is used to form an organic light-emitting layer by dissolving or dispersing luminous materials and dispensing the resultant dispensing solution from a head of an ink-jet printer. The ink jet method is relatively simple in terms of the process, but has problems in that its output is low, thickness of the layer is not uniform, and it is difficult to apply to a large-size display device.

In an exemplary embodiment according to the present invention, a laser induced thermal imaging apparatus includes a chamber, a substrate stage, an adhesion frame and a laser oscillator. The chamber has a donor film and a substrate and is adapted to carry out a process for laminating the donor film on the substrate. The substrate stage has a first electromagnet, and is positioned in the chamber to support the substrate. The adhesion frame has a second electromagnet, and is positioned over the substrate stage. The donor film and the substrate are disposed between the substrate stage and the adhesion frame in the chamber. The laser oscillator is adapted to apply a laser output to the donor film.

In another exemplary embodiment according to the present invention, a laser induced thermal imaging method is provided. A donor film and a substrate positioned between a substrate stage and an adhesion frame are laminated. An electric current is supplied to the substrate stage and the adhesion frame to generate a magnetic force in the substrate stage and the adhesion frame due to the current. The donor film is adhered to the substrate using the magnetic force.

These and/or other aspects and features of the invention will become apparent and be more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is an exploded perspective view showing an example of a laser induced thermal imaging apparatus according to an exemplary embodiment of the present invention; and

FIGS. 2A to 2E are cross-sectional views showing a laser induced thermal imaging method according to an exemplary embodiment of the present invention.

Hereinafter, certain exemplary embodiments according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view showing an example of a laser induced thermal imaging apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 1 , the laser induced thermal imaging apparatus according to an exemplary embodiment of the present invention includes a chamber 100 , a substrate stage 200 , an adhesion frame 300 , a laser oscillator 400 and elevating units 500 a , 500 b.

In the chamber 100 , a process for laminating a donor film 350 , which is a deposition source, is performed to transfer a predetermined organic material onto a substrate 250 . Accordingly, as the apparatus for carrying out the process for laminating the substrate 250 and the donor film 350 , at least the substrate stage 200 and the adhesion frame 300 are included within the chamber 100 . During the lamination process, the chamber 100 is in a vacuum state.

The substrate stage 200 is composed of a first arrangement groove (or a depressed region) 202 a and a second arrangement groove 202 b for arranging the substrate 250 and the donor film 350 , respectively. Generally, the second arrangement groove 202 b is formed around the periphery of the first arrangement groove 202 a along the shape of the donor film 350 since the donor film 350 has a larger area than that of the substrate 250 . The first arrangement groove 202 a and the second arrangement groove 202 b are formed with a predetermined stepped difference, and the second arrangement groove 202 b is formed with a higher predetermined height than that of the first arrangement groove 202 a . Also, the substrate stage 200 includes at least one first electromagnet 210 . The first electromagnet 210 may be disposed on a single plane, but a plurality of the first electromagnets 210 may also be formed into a concentric circle, or arranged in a plurality of horizontal and perpendicular rows.

The adhesion frame 300 has a second electromagnet 310 , and it is positioned over the substrate stage 200 . The donor film 350 and the substrate 250 are disposed between the substrate stage 200 and the adhesion frame 300 in the chamber 100 . In addition, at least one opening 311 having a pattern corresponding to a portion of the donor film 350 to be transferred is formed in the adhesion frame 300 . That is to say, the donor film 350 should be transferred onto the substrate 250 as much as a volume of the organic material to be transferred since the donor film 350 is used as a transfer source for transferring an organic material onto the substrate 250 . Accordingly, a predetermined pattern of the opening 311 is formed in the adhesion frame 300 so as to transfer a desired area of the donor film 350 onto the substrate 250 . In addition, the adhesion frame 300 itself may be formed into the second electromagnet 310 , and may also be formed by adhering the second electromagnet 310 to the upper or lower portion of the adhesion frame 300 . The adhesion frame 300 may be fixed by an adhesion frame tray 301 to be driven up and down.

The laser oscillator 400 may be located at the outside or inside of the chamber 100 , and it may be positioned over the adhesion frame 300 to apply a laser output onto the adhesion frame 300 (and to the donor film 350 through the at least one opening 311 ).

The elevating units 500 a , 500 b may be divided into the first elevating unit 500 a and the second elevating unit 500 b . The first elevating unit 500 a has at least one first pin 550 a adapted to driving the substrate 250 up and down, and the second elevating unit 500 b has at least one second pin 550 b adapted to driving the donor film 350 up and down. As an example, at first, the first elevating unit 500 a moves up to receive the substrate 250 from a translocation apparatus (Not shown), and then moves down to arrange it in the first arrangement groove 202 a . Subsequently, the second elevating unit 500 b moves up to receive the donor film 350 from the translocation apparatus (Not shown), and then moves down to arrange it in the second arrangement groove 202 b . The substrate 250 and the donor film 350 are laminated using such an operation. Here, the donor film 350 is fixed by a film tray 351 such that it can move up.

The aforementioned laser induced thermal imaging apparatus according to an exemplary embodiment of the present invention further includes an elevating drive unit 320 (see FIGS. 2A-2E ) coupled to the adhesion frame 300 , such that the adhesion frame 300 can be driven up and down by the elevating drive unit. That is to say, since the adhesion frame 300 includes the second electromagnet 310 , it becomes a magnet to generate a magnetic field if a predetermined electric current is applied to the adhesion frame 300 . Accordingly, the elevating drive unit may include or be coupled to a current source for applying an electric current to the adhesion frame 300 so that adhesion strength and operation of the adhesion frame 300 can be controlled according to a magnitude and direction of the electric current.

FIGS. 2A to 2E are cross-sectional views showing a laser induced thermal imaging method according to an exemplary embodiment of the present invention.

Referring to FIGS. 2A to 2E , in the laser induced thermal imaging method according to an exemplary embodiment of the present invention, the substrate 250 is first arranged on the first arrangement groove 202 a of the substrate stage 200 in the chamber 100 using an end effector 700 . For this, the first elevating unit 500 a moves up to receive the substrate 250 from the end effector 700 using first pins 550 a equipped in the first elevating unit 500 a , and to support the substrate 250 ( FIG. 2A ). The end effector 700 is then removed out of the chamber 100 ( FIG. 2B ).

As the next process, the donor film 350 is arranged on the second arrangement groove 202 b of the substrate stage 200 using the end effector 700 . For this, the second elevating unit 500 b moves up to receive the donor film 350 from the end effector 700 using second pins 550 b equipped in the second elevating unit 500 b , and to support the donor film 350 ( FIG. 2C ). Then, the donor film 350 is laminated onto the previously disposed substrate 250 . Here, the donor film 350 is arranged on the second arrangement groove 202 b while it is fixed by the film frame 351 ( FIG. 2D ).

Subsequently, the adhesion frame 300 is closely adhered onto the donor film 350 by controlling the adhesion strength so that a fine gap cannot be formed between the substrate 250 and the donor film 350 , which are closely adhered to each other. Then, the adhesion frame 300 moves down while it is fixed by the adhesion frame tray 301 . An adhesion property between the substrate 250 and the donor film 350 may be improved by controlling the adhesion strength between the adhesion frame 300 and the substrate support 200 since the electromagnet 210 is equipped in the inside of the substrate stage 200 . Subsequently, the next laser transfer process is carried out on the adhesion frame 300 equipped with a predetermined pattern of openings 311 using a laser oscillator 400 . At this time, the donor film 350 is transferred in a predetermined pattern onto the substrate 250 since it is a transfer source (or deposition source) for transferring organic materials to the substrate 250 . Accordingly, a predetermined pattern of an organic material is transferred onto the substrate 250 by irradiating the laser onto the adhesion frame 300 since the adhesion frame 300 has a predetermined pattern of openings. That is to say, the adhesion frame 300 may function as a mask where the laser may be irradiated only through its predetermined region ( FIG. 2E ).

According to the aforementioned laser induced thermal imaging method in an exemplary embodiment of the present invention, the aforementioned process may be progressed by fixing the substrate stage 200 for supporting the substrate 250 and driving the adhesion frame 300 down in the method that the substrate 250 and the donor film 350 are laminated, and then closely adhered to each other using the adhesion frame 300 . And, when a process shown in FIG. 2E is completed, the adhesion frame 300 moves up again and returns to an original position using the elevating drive unit.

The laser induced thermal imaging apparatus and laser induced thermal imaging method according to an exemplary embodiment of the present invention may be useful to prevent a fine gap from being generated between the donor film and the substrate. Accordingly, the laser induced thermal imaging apparatus and laser induced thermal imaging method according to an exemplary embodiment of the present invention may improve the bonding property between the substrate and the donor film, and therefore improve lifetime, yield and reliability of the device.

Although certain exemplary embodiments of the present invention have been shown and described in detail, it would be appreciated by those skilled in the art that the description proposed herein is just an example for the purpose of illustrations only, and not intended to limit the scope of the invention. And, it should also be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.