Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – Amorphous semiconductor
Reexamination Certificate
2001-10-17
2004-01-20
Whitehead, Jr., Carl (Department: 2822)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
Amorphous semiconductor
C438S486000, C438S308000, C438S795000
Reexamination Certificate
active
06680242
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a method of forming a crystalline semiconductor thin film on a substrate, a lamination formed with a crystalline semiconductor thin film on a substrate, a lamination for use in a substrate provided with a transparent conductive thin film and a transparent semiconductor thin film used for production of various kinds of display devices such as CCD cameras or liquid crystal display devices or camera image sensors, particularly, for the color filter suitable to portable terminals such as portable telephones or small personal computers, as well as color filters manufactured by using the substrate.
2. Description of the Related Art
Photoconductors having catalytic activity or photovoltaic activity have been noted for their specific applications in recent years. For example, titanium dioxide as a photosemiconductor is said to oxidatively decompose organic contaminants deposited on the surface, air contaminating substances such as nitrogen oxides (NOx), sulfur oxides (SOx) and malodor substances, as well as bacteria by the oxidizing action based on the photocatalytic activity. As actual application examples, various uses have been proposed such as a method of appending a titanium dioxide photocatalyst on outer walls of buildings to elate air contaminating substances under sunlight. (Japanese Published Unexamined Patent Application No. Hei 6-315614). A method of appending a titanium dioxide catalyst on walls or hand rails in hospitals thereby killing bacteria (Japanese Published Unexamined Patent Application No. Hei 7-102678), a method of dispersing a powder of titanium dioxide catalyst in waste water and applying the light of a UV-ray lamp to decompose dirt in water (Japanese Published Unexamined Patent Application No. Hei 5-92192) or a method of utilizing a self-cleaning effect of a photocatalyst in order to mitigate cleaning maintenance for fluorescent lamps or illumination instruments (Japanese Published Unexamined Patent Application Hei 9-129012).
Further, it has been known that the surface of the photoconductive thin film is rendered a highly hydrophilic based on the photoreaction, and various application uses have been considered for preventing clouding of mirrors (in bath rooms or automobiles), lenses and glass windows.
It has also been known that a self-cleaning effect is obtained when the photosemiconductor thin film is formed on surfaces of building outer walls, automobile glass and window glass, hydrophobic dirt is less deposited and, in addition, dirt, if deposited, is decomposed based on the hydrophilic property on the surface of the film and the dirt or the decomposition products thereof are easily flushed away by rain fall or water washing due to the hydrophilic property of the photoconductor thin films.
For the preparation of photosemiconductor thin films, there have been known a method of hydrolyzing a titanium compound such as titanium alkoxide or titanium acetate, coating and drying the product on the surface of a base material and then sintering at a temperature of 500° C. or higher thereby obtaining an anatase type titanium dioxide film, a method of forming an amorphous titanium dioxide layer by a vapor deposition process and annealing the resultant amorphous titanium dioxide layer at 400° C. or higher to form a layer containing anatase type titanium dioxide, a method of crystallizing the surface of metal titanium by oxidizing at a temperature of 500° C. or higher or a method of obtaining an anatase type titanium dioxide film by an RF sputtering method in a state of heating a base material to 250° C. or higher.
In the methods described above, the method of forming a photosemiconductor thin film by sintering the amorphous titanium dioxide film requires heating of the substrate at a high temperature for a long time, which increases the cost in view of economy. Further, formation of the photoconductor thin film by this method on a plastic base material to be described later is actually impossible in view of the heat resistance of the plastic substrate. Further, while the RF sputtering method is excellent as a method of obtaining an anatase titanium dioxide of high photovoltaic activity, it is necessary to use an expensive apparatus and it is difficult to manufacture the photoconductor thin film at a reduced cost by this method. Although some of plastic base materials have heat resistance of 250° C., those having heat resistance of 250° C. and also having transparency and available at a reasonable cost have not yet been known at present.
By the way, the photoconductor thin film has been noted for the photovoltaic function in addition to characteristics such as antifouling, antibacterial and anti clouding effect based on the photochemical reaction on the surface as described above. The photovoltaic effect is a phenomenon that when a substrate provided with a conductive thin film and a photoconductor thin film is dipped in water or a solution having an electrolyzing function and UV-rays are applied to the photoconductor thin film, photovoltaic activity is generated at the irradiated area. By utilizing the phenomenon, a film can be formed selectively for example to the irradiated area. That is, when the substrate is dipped in an electrodeposition solution containing a film forming electrodeposition substance and UV-rays are applied to the photoconductive thin film in a state of applying or not applying a bias voltage between the conductive thin film and a counter electrode located in the solution, photovoltaic activity is generated at the light-irradiated area of the photosemiconductor thin film and the film forming substance is electrodeposited to the area. In the case where the photovoltaic activity of the semiconductor thin film is sufficiently large, the bias voltage can be reduced to 0.
The present inventors have previously filed a method of forming an extremely fine pattern at a good resolution which is useful for a color filter or the like by utilizing the photovoltaic activity (Japanese Published Unexamined Patent Application Nos. Hei 1-174790, Hei 11-133224, and Hei 11-335894).
In recent years, liquid crystal display panels provided with color filter include (1) those having a driving substrate on which driving elements such as thin film transistors (hereinafter sometimes referred to as “TFT”) and pixel electrodes are arranged in a matrix and a filter substrate having a color filter and a counter electrode which are opposed under positional alignment by way of a spacer in which a liquid crystal material is sealed in a gap portion and (2) those having a color filter-integrated type driving substrate with the color filter being formed directly to the driving substrate and a counter substrate having an electrode opposed to each other simply by way of a spacer in which liquid material is sealed in the gap portion. Each of the color filters described above can be manufactured by the photo-electrodeposition method using the photosemiconductor thin film as described in the patent publications.
The former liquid crystal display panel involves the problem in that an exposure mask is required upon manufacture of the color filter and error tends to occur in the accuracy of the positional alignment between both of the driving and filter substrates to lower the display quality or production yield. On the other hand, the latter has been noted at present since a bias voltage can be applied selectively by TFT disposed on the driving substrate (addressing), so that the exposure mask is not necessary and positional alignment is not required between both of the substrates the manufactured of the color filter. However, the latter method leads to increase cost since it is necessary to make the color filter conductive by using through holes or the like.
Further, in recent years, demand for smaller size equipment as portable terminals such as telephones or small personal computers has tended to increase rapidly and various studies have been made with a viewpoint of portable performance. Particularly, in the
Akutsu Eiichi
Ohtsu Shigemi
Shimizu Keishi
Yatsuda Kazutoshi
Fuji 'Xerox Co., Ltd.
Hogans David L.
Jr. Carl Whitehead
Oliff & Berridg,e PLC
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