Patent Application
20060154407
This application claims the benefit of Korean Patent Application Nos. 2005-0000965 and 2005-0000966, filed on Jan. 5, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a device that prevents thermal deformation of a glass substrate needed for an organic semiconductor device and more particularly, to a shadow mask frame having heat-radiating and cooling functions, and a chuck plate used in attaching a glass plate to a shadow mask and having a cooling means, in which a refrigerant is circulated in the chuck plate, thereby preventing the temperature from increasing in the glass plate due to radiant heat from a deposition source under a vacuum atmosphere or conductive heat caused by contact with a shadow mask, thereby improving precision of the alignment between the glass substrate and the shadow mask.
2. Discussion of Related Art
Generally, an organic thin film of an organic semiconductor device such as an organic light emitting diode, for example, is formed by evaporating a low molecular organic material under a vacuum atmosphere, or by using a spin coating method, a dip coating method, a doctor blade, or an inkjet printing method after dissolving a polymer organic material in a solvent.
In particular, where the thin film including the low molecular organic material is fabricated in the vacuum atmosphere, a shadow mask having a predetermined pattern is needed for depositing an organic material at a proper layer. The shadow mask is fixed to a shadow mask frame. When a glass substrate is provided it is aligned with and attached to the shadow mask, and then a film growth process is performed. During the film growth process, a dotted-type or linear-type organic material deposition source is used to deposit the low molecular organic material on the glass substrate according to a predetermined pattern.
In the above described deposition process, radiant heat R is transferred from the deposition source to the shadow mask and, thus, increasing its temperature . As the temperature of the shadow mask rises, it thermally expands and thereby decreases the precision of a pattern position of an organic light emitting diode. This reduces the precision of the pattern position for representing red R, green G and blue B colors and results in the mixing of R, G and B colors, which is known as “discoloration defective.”
Further, the glass substrate is affected by not only the radiant heat from the deposition source but also conductive heat due to direct contact with the shadow mask, so that the temperature of the glass substrate continuously rises. Particularly, in the case of the glass substrate, it is difficult to radiate away the heat, which accumulates via successive deposition processes. Therefore, the difference in thermal deformation between the glass substrate and the shadow mask becomes larger when only the shadow mask frame is cooled.
Accordingly, it is an aspect of the present invention to provide a shadow mask frame assembly which has a heat-radiating function to fundamentally prevent a radiant heat transfer from a deposition source, and a cooling function to prevent the heat from being accumulated in a shadow mask, thereby suppressing thermal expansion of the shadow mask. This improves the precision of a pattern position of an organic light emitting diode.
An embodiment of the invention provides a chuck plate assembly that includes a shadow mask formed with a predetermined pattern; a shadow mask frame to which the shadow mask is attached; and a cooling plate mounted on a portion of the shadow mask frame exposed to a deposition source.
Another embodiment of the invention provides a chuck plate assembly that includes a shadow mask formed with a predetermined pattern; a shadow mask frame for holding the shadow mask; a substrate aligned with the shadow mask and to which a deposition material from a deposition source is deposited; and a chuck plate attaching the substrate to the shadow mask by having a front surface facing the deposition source closely attached to a back surface of the substrate facing away from the deposition source, wherein the chuck plate includes a refrigerant circulating duct through which a refrigerant circulates.
In yet another embodiment of the invention, a chuck plate assembly further comprises an external cooling plate mounted on a back surface of the chuck plate opposite surface attached to the substrate. In this embodiment, the external cooling plate, rather than the chuck plate, includes the refrigerant circulating duct through which the refrigerant circulates.
These and other aspects of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with accompanying drawings.
Hereinafter, preferable embodiments according to the present invention will be described with reference to the accompanying drawings, wherein embodiments of the present invention are provided to be readily understood by those skilled in the art.
As shown in
A heat radiating method or a cooling method can be used to suppress the thermal expansion of the shadow mask 120. The heat-radiating method intercepts the radiant heat R from the deposition source 170. The cooling method prevents the heat from being accumulated in the shadow mask 120.
According to an embodiment of the present invention, a cooling plate 60 can be mounted to a portion of the shadow mask frame 110 facing the deposition source 170, thereby performing both the heat-radiating and cooling methods. The cooling plate 60 intercepts the radiant heat R from the shadow mask frame 110 and removes the heat accumulated in the shadow mask frame 110.
The cooling plate 60, which is mounted to the mask frame 110 that faces the vertical type deposition source 170 and is exposed to the radiant heat, prevents the temperature of the shadow mask frame 110 from rising. This prevents deformation of the shadow mask 120 due to the thermal expansion, thereby enhancing precision in a pattern position.
In the meantime, a problem may arise wherein the cooling plate 60 may obstruct a deposition material from the vertical type deposition source 170 and thus decrease a film growth region of the substrate.
To solve this problem, the cooling plate 60 may include an exposure portion 60a facing the deposition source 170, and an inner portion 60b facing the film growth region as shown in
Preferably, the cooling plate surrounds the mask frame entirely so as to heighten the heat-radiating and cooling effects of the mask frame.
Further, the cooling plate 60 according to an embodiment of the present invention can be made of various heat-radiating materials as known to those persons of ordinary skill in the art.
Looking at
To solve this problem, the present invention can provide a chuck plate for cooling a glass substrate according to another embodiment of the present invention, as shown in
Referring to
The chuck plate 140 supports the glass substrate 130 from its back side and makes the glass substrate 130 be aligned with and attached to the shadow mask 120. The refrigerant circulating duct 41 is directly formed inside the chuck plate 140 so that a refrigerant is circulated through the refrigerant circulating duct 41, thereby cooling the glass substrate 130.
The chuck plate 140 can be made of aluminum and attached to cover a back side of the glass substrate 130 in the deposition process, thereby having a good cooling effect on the glass substrate 130.
The refrigerant circulating duct 41 can be formed inside the chuck plate 140 by various methods. The longer the refrigerant circulating duct 41 is, the better the cooling effect is given to the glass substrate 130. Thus, the refrigerant circulating duct 41 is preferably lengthened to enhance this cooling effect.
Further, the refrigerant circulating duct 41 can be designed in consideration of the size of the chuck plate 140 and the desired cooling effect, for example. As shown in
Additionally, a temperature adjuster (not shown) may be provided to adjust the temperature of the refrigerant circulating through the refrigerant circulating duct 41. In this case, the temperature of the refrigerant circulating through the refrigerant circulating duct 41 can be optimized in consideration of the temperature of the glass substrate 130 and the shadow mask 120. Further, a thermometer (not shown) may be provided to measure the temperature of the shadow mask 120.
Looking at
Further, the refrigerant circulates through the refrigerant circulating duct 41 formed inside the chuck plate 140 employed for making the shadow mask 120 be aligned with and attached to the glass substrate 130, so that the glass substrate 130 is cooled, thereby minimizing difference in the thermal deformation between the glass substrate 130 and the shadow mask 120.
As the temperature of the refrigerant circulating through the refrigerant circulating duct 41 is optimized in consideration of the temperature of the shadow mask 120, the temperature difference between the glass substrate 130 and the shadow mask 120 is minimized. Thus, an alignment error due to the thermal expansion of the glass substrate 130 and the shadow mask 120 is minimized, thereby improving precision in the alignment between the glass substrate 130 and the shadow mask 120.
As shown in
The same considerations that apply to refrigerant circulating duct 41, described above, also apply to refrigerant circulating duct 46.
The refrigerant circulating duct 46 has an inlet 47 placed at a first edge of the external cooling plate 45, and an outlet 48 placed at a second edge of the external cooling plate 45. Alternatively, the inlet and the outlet of the refrigerant circulating duct may be placed at the same edge of the cooling plate 45. A temperature adjuster (not shown) and a thermometer (not shown) may also be used to optimize the temperature of the glass substrate 130 and the shadow mask 120.
Referring to
As described above, when the cooling plate is mounted to a portion of the shadow mask frame facing the deposition source, not only the radiant heat from the deposition source is intercepted by cooling plate 60, but also the temperature of the shadow mask itself is prevented from rising, so that deformation of the shadow mask due to thermal expansion is prevented, thereby also preventing degradation of the pattern position precision caused by the thermal expansion of the shadow mask 120.
It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2005-0000965 | Jan 2005 | KR | national |
| 10-2005-0000966 | Jan 2005 | KR | national |
