Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Including integrally formed optical element
Reexamination Certificate
1999-12-07
2003-01-07
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Including integrally formed optical element
C438S149000, C430S007000
Reexamination Certificate
active
06503772
ABSTRACT:
BACKGROUND OP THE INVENTION
1. Field of the Invention
The present invention concerns a technique for forming a color filter used for CCD cameras, or various kinds of indicating elements, for example, liquid crystal display elements or color sensors and. it relates to a method of manufacturing colored layers or a black matrixes. More specifically. it relates to a method of manufacturing a new color filter capable of forming a colored layer or a black matrix simply and conveniently and at high resolution.
2. Description of the Related Art
Method of manufacturing color filters known at present includes (1) a dying method, (2) a pigment dispersion method, (3) a printing method, (4) an ink jet method, (5) an electrodeposition method and (6) a micelle electrolysis method.
Among them, both of (1) the dying method and (2) the pigment dispersion method have attained a high degree of technical completion and have been used generally for solid state color image pick-up devices but they require patterning by way of the step of photolithography, therefore causing a problem in view of the number of steps and high cost.
On the other hand, the printing method (3) and the ink jet method (4) require no photolithography step. However, the printing method (3) is a process of printing and then curing a thermosetting resin in which a pigment is dispersed and poor in view of resolution power or the uniformity of the film thickness. The ink jet method (4) is a process of forming a certain ink receiving layer, applying hydrophilic/hydrophobic treatment and then blowing ink to a hydrophilic portion to obtain a color filter layer but it involves a problem in view of the resolution power and high possibility of mixing color in adjacent filter layers and positional accuracy.
Color filters are generally formed by each of the methods on the side of an ITO substrate opposed to a TFT substrate. However, if the filter in formed at that position, it is necessary to positionally align the TFT substrate and the color filter substrate, making it difficult for attaining a high accuracy and increasing the cost.
The electrodeposition method (5) comprises applying a high voltage of about 70 V an a previously patterned transparent electrode in a solution of an electrolyte in which a pigment in dispersed in a water soluble polymer, and forming an electrodeposition film to conduct electrodeposition coating and repeating the steps for three times to obtain an R.G.B color filter. Since this method requires patterning for a transparent electrode by photolithography, which is used as an electrode for electrodeposition, it involves a drawback that the shape of the pattern in restricted and cannot be used for TFT liquid crystals. Further, if a color filter can be formed integrally by electrodeposition on a pixel electrode of a TFT liquid crystal substrate, no additional patterning is required. However, an electrodeposition voltage is high and it is extremely difficult to conduct electrodeposition to transparent pixel electrodes in an active matrix circuit in the existent electrodeposition method, making electrodeposition utilizing the pixel electrode of TFT impossible. Furthermore, it cannot be utilized, for example, by a reason that a driving voltage is increased since the color filter layer is insulative.
Japanese Published Examined Patent Application No. Hei 2-59446 describes to form a multi-colored device by forming a plurality of transparent conductive layers made of ITO, etc. being insulated from each other on a substrate, and repeatedly forming colored layers based on polymeric layers electrodeposited selectively on each of the conductive layers and discloses the use of a solution containing a water soluble polymer and a pigment as an electrodeposition solution. Japanese Published Examined Patent Application No. Hei 3-45804 discloses a method of using a substrate in which a TFT and a pixel electrode connected with the TFT are formed, driving the TFT in a state where the pixel electrode, a water soluble polymer and a dye-containing electrodeposition solution are in contact with each other thereby electrodepositing a colored film on a pixel electrode. Further, it describes repeating curing and formation of electrodeposition film on every color and, furthermore, forming a transparent electrode on the electrodeposition film. Japanese Published Examined Patent Application No. Hei 5-49967 discloses a method of forming a plurality of electroconductive transparent electrodes for liquid crystal display disposed being insulated on a substrate and selectively forming colored films by optionally applying a voltage selectively to the electrode.
Further, Japanese Published Unexamined Patent Application No. Hei 5-5874. for example, proposes a technique of forming a color filter integrally on the side of a TFT substrate. However, an electrodeposition film manufactured by a usual electrodeposition technique is insulative and, when the color filter is manufactured on a pixel electrode for liquid crystal driving, it cannot be utilized since the driving voltage for liquid crystals is increased. Further, impurities such as a surface active agent and the like are contained in usual electrodeposition films, purity of color or permeability is deteriorated or it is necessary to protect a TFT circuit from alkali metals contained in the film. Further, direct electrodeposition to the pixel electrodes the utilizing usual TFT driving circuits is impossible and therefore a TFT of high voltage withstand in necessary. In view of the above, a method of integrally forming a color filter substrate and a TFT substrate can not be put to practical use so far.
The micelle electrolysis method (6) is a sort of an electrodeposition method, and a voltage required for electrodeposition is lover since oxidation/reduction of ferrocene used an a deposition material is utilized, so that a color filter can be formed integrally by electrodeposition on the TFT liquid crystal substrate. However, in the thin film formed by the micelle electrolysis method, since ferrocene or surface active agent indispensable for the forming step are taken in and mixed as impurities, the color filter thus formed has poor permeability and poor color purity and has high resistivity. Further, it takes a long time such as several tens of minutes for electrodeposition to worsen the production efficiency. In addition, the ferrocene compound as the essential ingredient for electrolysis is extremely expensive to provide a problem in view of the cost.
Further, a color filter cannot generally be used as a color filter layer alone but a portion between each of the color filters and the pixel elements has to be covered with a black matrix. Usually, photolithography is used for forming the black matrix, and this is a major factor of increasing the cost. Accordingly, a method of manufacturing a color filter of a high resolution power with high controllability, and not using the photolithography and thus with less number of steps has not yet been known at present when considering the R.G.B. layer and the black matrix together, which causes poor yield and increase the cost in the production of the color filter.
SUMMARY OF THE INVENTION
The present invention provides a manufacturing method capable of manufacturing a high performance thin film transistor-integrated type color filter for use in liquid crystal display element, capable of saving alignment between a color filter and a TFT substrate, with less number of steps, reduced at the cost, having a high aperture ratio, high resolution and high controllability, by integrally forming a color filter by an electrodeposition method on the side of a substrate formed with a thin film transistor (hereinafter properly referred to as TFT).
The inventors of the present invention have reconsidered the electrodeposition technique itself in view of the principle. Then, the inventors have noted on compounds used for the method of manufacturing a filter proposed previously by the inventors as the photoelectrodeposition technique, which are water soluble and greatly chan
Akutsu Eiichi
Ohtsu Shigemi
Shimizu Keishi
Tomono Takao
Fuji 'Xerox Co., Ltd.
Tsai Jey
LandOfFree
Method of manufacturing a thin film transistor-integrated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing a thin film transistor-integrated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing a thin film transistor-integrated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3004290