Hitachi, Ltd.

Yasushi Nakano

Ryoji Oritsuki

Nobuyuki Suzuki

Kazuhiko Horikoshi

Takuo Tamura

Miwako Nakahara

Takeo Shiba

Kiyoshi Ogata

Makoto Ohkura

Toshihiko Itoga

Takahiro Kamo

Klyoshi Ogata

A liquid crystal display device includes first and second substrates, a liquid crystal layer, a plurality of video signal lines and scanning signal lines formed on the first delimiting pixel regions, a plurality of video signal line driving circuits, and a thin film transistor formed in the pixel regions, and driven by a scanning signal from a scanning signal line. A display area contains a plurality of the pixel regions and a first and second protection element lines are formed at a peripheral portion of the display area and connected to the video signal lines by first and second high-resistance elements. A first circuit board is electrically connected with a portion of the video signal line driving circuits and a second circuit board is electrically connected with another portion of the video signal line driving circuits.

Liquid crystal display device

A liquid crystal display device having a first substrate, a second substrate, a liquid crystal layer interposed between the first substrate and the second substrate, a plurality of video signal lines and scanning signal lines formed on the first substrate, and defining pixel regions, a thin film transistor formed in the pixel regions, and driven by a scanning signal from the scanning signal line for supplying video signal from one of the video signal lines to a pixel electrode and a display area containing a plurality of the pixel regions. A first protection element line formed at a peripheral portion of the display area, and being connected to a odd-numbered ones of the video signal lines by first high-resistance elements, and a second protection element line formed at a peripheral portion of the display area, and being connected to even-numbered ones of the video signal lines by second high-resistance elements.

Inexpensive, unannealed glass is used as a substrate. The surface of a polycrystalline silicon film doped with boron (B) or phosphorus (P) is oxidized with ozone at a processing temperature of 500&#xb0; C. or below to form a silicon oxide film of 4 to 20 nm thick on the surface of polycrystalline silicon. On account of this treatment, the level density at the interface between the gate-insulating layer and the channel layer can be made lower, and a thin-film transistor having less variations of characteristics can be formed on the unannealed glass substrate.

Process for manufacturing thin film transistor on unannealed glass substrate

To a polycrystalline silicon layer crystallized by irradiation with laser light, a mixed gas comprised of ozone gas and H O or N O gas is fed at a processing temperature of 500&deg; C. or below, or the polycrystalline silicon layer is previously treated with a solution such as ozone water or an aqueous NH /hydrogen peroxide solution, followed by oxidation treatment with ozone, to form a silicon oxide layer with a thickness of 4 nm or more at the surface of the polycrystalline silicon layer for forming a thin-film transistor having characteristics that are less varying on a glass substrate previously not annealed.

Thin-film transistor and method of manufacturing the same

To a polycrystalline silicon layer crystallized by irradiation with laser light, a mixed gas comprised of ozone gas and H O or N O gas is fed at a processing temperature of 500&deg; C. or below, or the polycrystalline silicon layer is previously treated with a solution such as ozone water or an aqueous NH /hydrogen peroxide solution, followed by oxidation treatment with ozone, to form a silicon oxide layer of 4 nm or more thick at the surface of the polycrystalline silicon layer for forming a thin-film transistor having less variations of characteristics on an unannealed glass substrate.

Process of manufacturing a thin-film transistor

Pixel areas surrounded by scanning signal lines, video signal lines, and counter signal lines are formed on a liquid-crystal-side surface of a transparent substrate, and include thin-film transistors driven by scanning signals from the scanning signal lines, pixel electrodes to which video signals from the video signal lines are supplied via the thin-film transistors, and counter electrodes spaced apart from the pixel electrodes and connected to the counter signal lines. To prevent leakage current from flowing from the scanning signal lines or the video signal lines to the counter signal lines, a common line is formed around a display area constituted by the pixel areas, the video signal lines and the scanning signal lines are connected to the common line by non-linear elements, and the counter signal lines are connected to the common line by high-resistance elements.

Inexpensive, unannealed glass is used as a substrate. The surface of a polycrystalline silicon film doped with boron (B) or phosphorus (P) is oxidized with ozone at a processing temperature of 500&deg; C. or below to form a silicon oxide film of 4 to 20 nm thick on the surface of polycrystalline silicon. On account of this treatment, the level density at the interface between the gate-insulating layer and the channel layer can be made lower, and a thin-film transistor having less variations of characteristics can be formed on the unannealed glass substrate.

Growing community of inventors

Mobara, Japan

Yasushi Nakano