Etching a substrate: processes – Forming or treating a sign or material useful in a sign – Sign or material is electroluminescent
Reexamination Certificate
2002-09-20
2004-06-29
Olsen, Alllan (Department: 1763)
Etching a substrate: processes
Forming or treating a sign or material useful in a sign
Sign or material is electroluminescent
C216S011000, C216S024000, C216S067000, C427S470000, C427S535000, C345S033000, C345S055000, C428S117000, C428S141000, C428S320200
Reexamination Certificate
active
06755983
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thin film formation technology suitable for manufacturing a display and a color filter having an EL (electroluminescence) device or an LED (light emitting diode), and more particularly to a technology advantageous for forming a multi-layer thin film layer between partition elements.
BACKGROUND ART
An ink jet method has been used to fill material, such as color resin, to organic semiconductor film of a display or to a color filter to manufacture liquid crystal panels for color display.
When material is filled by an ink jet method, it is necessary to form partition elements to partition pixel areas (hereafter also called “banks”, a layer to form partition elements is called a “bank layer”), and to fill a thin film material solution to the area enclosed with the partition elements. A thin film material solution, which volume is much larger than the volume after film formation, is filled in the pixel area enclosed with the partition elements. Since a display is generally demanded to be slim, the height of the partition elements is limited. Therefore the behavior of the thin film material solution filled there differs depending on the wettability (affinity) which the partition elements and the area enclosed with the partition elements have for the thin film material solution.
If the partition elements have affinity for the material, the material easily flows over to the adjacent pixel areas, even if the partition elements exist, when an amount of material exceeding the height of the partition elements is filled, as shown in FIG.
9
A. If the partition elements have no affinity for the material, the material does not flow over to the adjacent pixel areas due to the surface tension of the material, even if the amount of material exceeding the height of the partition materials is filled, as shown in FIG.
9
B. If this material is heated to evaporate the solvent, thickness after film formation becomes thick at the center of the pixel area and thin at the edges, since the material is repelled by the side walls of the partition elements, as shown in FIG.
9
C. This causes color unevenness and reduces reliability. Also if the partition elements are comprised of non-affinity elements, adhesion of the partition elements and ground plane of the partition elements is weak, which makes partition elements easily separate.
A prior art to solve such problems is a surface treatment technology to make the top of the partition elements have no affinity land to make the other portions have affinity. Japanese Patent Laid-open No. 9-203803 and Japanese Patent Laid-open No. 9-230129, for example, disclose a technology to process the top portion of the partition elements to be ink repellent by irradiating ultraviolet rays, and the area enclosed with the partition elements to have affinity for ink. For the former, an ink repellent (non-affinity) layer is coated at the top portion of the partition elements, and for the latter, the concave portion enclosed with the partition elements is made to have affinity for ink (affinity) by ultraviolet irradiation. Logical considerations of this technology are written in International Display Research Conference 1997, pp. 238-241. According to this technology, even if material is filled to the height exceeding the height of the partition elements, the material is repelled by the non-affinity film, and does not overflow to the adjacent pixel areas, as shown in
FIG. 10A
, since the side walls of the partition elements have affinity, and the thickness of formed film does not become thin at the edges of the pixel areas.
However, even in the above known technology, it is not clear how to set affinity of the side walls of the partition elements, therefore it is difficult to obtain a flat thin film layer. Japanese Patent Laid-open No. 9-230129 states that the degree of affinity is controlled by irradiating ultraviolet rays from both the front and back sides, but the degree of affinity and non-affinity, that is, how to set the respective contact angle to the thin film material solution, is not known.
If the non-affinity is too high, for example, the thin film layer becomes thin at the edges near the partition elements and thick at the center as shown in FIG.
9
C. If affinity is too high, on the other hand, the thin film layer becomes thick at the edges near the partition elements and thin at the center as shown in FIG.
10
B.
Also the above known technology assumes that there is only one thin film layer, therefore it is totally unknown how to treat the surface for forming a flat thin film layer for each layer when multi-layered thin film layers are formed. If the above known technology is applied for each layer, surface treatment is required each time a layer is formed, which requires numerous processing steps.
DISCLOSURE OF THE INVENTION
The present inventor discovered that if plasma treatment is performed using fluorine gas, the contact angle to ink is greatly different between an organic substance and an inorganic substance, depending on the mixing ratio of oxygen gas and fluorine gas. The present inventor also discovered that affinity can be controlled by forming banks where affinity material and non-affinity material are alternately layered and by executing plasma treatment.
It is accordingly a first object of the present invention to provide a thin film formation method which allows the formation of multi-layer thin films by laminating a bank using different materials.
A second object of the present invention is to control affinity without going through many processing steps for affinity control by managing surface treatment under predetermined conditions, so as to decrease the cost required for affinity control and to form multi-layer thin films having a uniform film thickness.
A third object of the present invention is to provide a display layered by the thin film formation method which can form multi-layer films. By this, image display without uneven brightness and color is implemented and reliability is improved.
A fourth object of the present invention is to provide a color filter layered by the thin film formation method which can form multi-layer films. By this, image display without uneven brightness and color is implemented.
To achieve the first object, the present invention is a thin film formation method for forming a thin film layer by filling a thin film material solution in areas enclosed with banks, comprising a step of forming the banks on a bank formation face, and a step of filling the thin film material solution in the banks. The step of forming the banks is for forming the banks where an affinity bank layer and a non-affinity bank layer are alternately layered by repeating the step of forming the affinity bank layer with an affinity material and a step of forming the non-affinity bank layer with a non-affinity material one or more times.
“Banks” here refer to partition elements which are formed to partition pixels of a display using a non-affinity semiconductor thin film device or to partition pixel areas of a color filter. For the layer structure of a bank, the type of non-affinity material or affinity material may be changed for each layer. The thickness of each layer to be layered may be changed for each layer. The bank formation face is a face where the banks are formed, and may be a drive board of a display or a transparent board of a color filter.
Affinity or non-affinity here is determined depending on the characteristics of the thin film material solution used to fill. If the thin film material solution has a hydrophilic property, for example, the surface having a polar group exhibits affinity, and the surface having a non-polar group exhibits non-affinity. If the thin film material solution has a lipophilic property, on the other hand, the surface having a polar group exhibits non-affinity, and the surface having a non-polar group exhibits affinity. The thin film material solution is selected in various ways depending on the manufacturing target. When the hydrophilic property or hydrophob
Olsen Alllan
Seiko Epson Corporation
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