Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2001-10-24
2004-01-27
Ton, Ming Toan T (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S040000, C438S030000
Reexamination Certificate
active
06683662
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a semiconductor device such as color LCD (Liquid Crystal Display device) and the like in which an active matrix display unit is employed and a process for the production thereof, more especially, to an improved semiconductor device in respect of the connection terminal structure of projected wires at the portion connecting to an external driving circuit.
RELATED ART
A liquid crystal display device wherein an active matrix display method is adopted can realize displaying full-color images, displaying high-contrast images, and displaying detailed images with high resolution.
In a display device to which an active matrix display method is applied, matrix electrode and plural of pixel electrodes are formed on the inner surface of an electrode substrate which faces another electrode substrate. Every pixel electrode has a thin film transistor (TFT) mounted thereon as an active switching element. This TFT operates in accordance with a matrix formation to switch its corresponding pixel electrode therethrough.
In order to operate each of switching elements in accordance with the matrix formation through TFT, each of these elements is required to be connected to LSI and the like of an external driving circuit. Each connection terminal of wires constituting wiring of the matrix electrode including TFT switching elements and located on a projected portion of a liquid panel substrate is covered with a transparent conductive film of chemically stable ITO (Indium-Tin-Oxide).
FIG. 11
shows an exemplary conventional structure of such a connection terminal as mentioned above.
FIG. 12
shows a side cross-sectional view taken along the line A—A of FIG.
11
.
In the area between the jogged ends of top and bottom glass substrates
1
,
2
wherein a connection element of a driving LSI is connected, a transparent conductive film
13
is deposited, and a metal wire
11
is formed therebeneath. In this case, the following problem will arise. Metal of the metal wire is easy to be ionized by water (moisture) penetrating through the transparent conductive film since the transparent conductive film is porous and less effective to shut off the infiltration of water under high humidity conditions. Consequently, metal corrosion occurs and the corroded metal leaches out between terminals to cause failure of interterminal current leak.
In order to solve this problem, this applicant (assignee) has proposed in Japanese Patent Kokai (Laid-open) No. JP-A-8-6059 (1996) an active matrix substrate in which an upper metal wire is removed of its terminal portion uncovered with an inorganic protective film or a connecting material connected to the terminal.
SUMMARY OF THE DISCLOSURE
However, in the active matrix substrate disclosed above there remains the following unsolved problem. When corrosion occurs in the portion of the upper metal wire to be connected to a wire of a plastic wire board, failure of interterminal current leak occurs at the same time. Explaining more in detail, the upper metal wire is generally covered with an anisotropic conductive film and connected to the wire of the flexible wire board via an anisotrapic conductive film by the tape-carrier package method. However, the anisotropic conductive film is water-absorbable to some extent so that water infiltrated through the anisotropic conductive film reacts with metal of the upper metal wire. In addition, in case that an impurity ion such as chlorine and the like is attached to either the anosotrapic conductive film or the flexible wire board, the attached impurity ion reacts with the metal. Consequently, metal corrosion occurs, and the corroded metal leaches out between the terminals to cause the failure of the interterminal current leak.
Accordingly, an object of the present invention is to provide a semiconductor device, including especially, active matrix liquid crystal display panel and the like, which is capable of inhibiting short circuit occurrence due to the interterminal current leak even under high humidity conditions, and a method for producing same.
According to an aspect of the present invention, there is provided a semiconductor device comprising plural lines of metal wires formed on a substrate each having a connection terminal positioned at the end of the substrate for connecting to an external driving circuit for applying voltage independently to every pixel electrode. The semiconductor device is characterized as follows: Each of the metal wires at the position of the connection terminal is provided with an interterminal anti-short-circuiting pattern including a conductive island and a recessor recesses located around the island; The surface of the metal wire except at least a portion of the island but including the inside of the recess thereon is covered with a protective insulating film; A contact hole is formed of the uncovered portion with the protective insulating film on the island; And a transparent conductive film is deposited on the surface of the protective insulating film including the inside of the contact hole and the top face of the island.
In this case, propagation of corrosion originating from the island formed on the connection terminal of the metal wire is intercepted by the recess, and accordingly, corrosion can be inhibited so as not to spread out of the island.
In an active matrix display method, matrix electrodes, plural pixel electrodes and active switching elements corresponding one by one to the pixel electrodes are used in being connected to each of metal electrodes except the aforementioned connection terminal end. The metal electrode except the connection terminal end constitutes a display portion on a substrate. Each of the pixel electrodes can be switched correspondingly to the matrix operation of the active switching elements. Liquid crystal is put into the space of the electrodes area located between the substrate and another substrate bonded opposing each other.
This constitution makes it possible to inhibit the occurrence of the interterminal current leak by the following reason. In the present invention, each of metal wires has an interterminal anti-short-circuiting pattern of conductive island and recess(es) on its connection terminal portion. Even though corrosion appears in the island area, the propagation of corrosion can be intercepted by the recess(es) located around the island, since the metal wire of a metal film except the island portion is covered with a protective insulating film effective to shut off the infiltration of water. Moreover, flow of metal eluted from island can also be stopped in the recess and never reaches outside. Accordingly, the occurrence of the interterminal current leak can be inhibited.
According to a second aspect of the present invention, there is provided a semiconductor device characterized by the following features.
Each of the metal wires at the position of said connection terminal is provided with an interterminal anti-short-circuiting pattern comprising conductive island and recess(es) located around said island; The surface of the metal wire except at least a portion of the island but including the inside of said recess(es) thereon are covered with a protective insulating film; A contact hole is formed of the uncovered portion with the protective insulating film on the island; A bottomed pool arriving at the recess is provided through the protective insulating film adjacent to said contact hole; A transparent conductive film is deposited on the surface of the protective insulating film, including inside of the contact hole and the bottomed pool.
According to a third aspect of the present invention, there is provided a semiconductor device characterized by the following features:
Each of said metal wires at the position of the connection terminal comprises an upper metal wire and a lower metal wire, with an interlaminer insulating film being interposed between the substrate and the lower metal wire; An interterminal anti-short-circuiting pattern comprising conductive island and recess(es) located around
Fujita Akira
Sugitani Choei
Hayes & Soloway P.C.
NEC LCD Technologies Ltd.
Ton Ming Toan T
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