Short circuit preventing film of liquid crystal electro-optical device and manufacturing method thereof
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsToshimitsu Konuma, Akira Sugawara, Yukiko Uehara
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Abstract
In an active matrix type liquid crystal electro-optical device using thin-film transistors, a metal film is formed on a transparent electrode that is opposed to the thin-film transistors. The metal film is oxidized by anode oxidation method using the electrode as an anode, to form a metal oxide film that serves as a short circuit preventing film. Alternatively, after a grid-shaped mask is formed on the metal film, the metal film is oxidized using the electrode as an anode, the mask is removed, and the metal film is again anode-oxidized, to form a non-oxidized portion. Thus, transparent and opaque regions, i.e., a black matrix is formed.
Claims22
A liquid crystal electro-optical device comprising:
- a pair of transparent substrates opposed to each other, each of said substrates having a transparent electrode formed thereon;
- and
- a liquid crystal layer interposed between said substrates,
- wherein one of said substrates includes a non-transparent film comprising a metal formed on portions of said transparent electrode and a transparent insulating film covering said non-transparent film and formed on an entire surface of said electrode, said transparent insulating film comprising an oxide of said metal;
- and
- wherein the other one of the substrates is provided with an active matrix circuit comprising thin film transistors.
A liquid crystal electro-optical device comprising:
- a first substrate having a plurality of pixel transistors and a plurality of pixel electrodes formed thereon;
- a second transparent substrate opposed to said first substrate;
- a counter transparent electrode formed on said second substrate;
- a light shielding means formed on said counter transparent electrode corresponding to said plurality of pixel transistors, said light shielding means comprising a metal film;
- a transparent insulating film covering said light shielding means and formed over an entire surface of said counter transparent electrode,
- wherein said transparent insulating film comprises an oxide of a same metal constituting said metal film.
A method for producing a liquid crystal electro-optical device, comprising the steps of:
- forming a metal film on a transparent electrode;
- forming a mask on a selected surface of the metal film;
- oxidizing an exposed surface of the metal film by a first anodic oxidation step where the portion of the metal film below said mask is not oxidized;
- removing the mask after the first anodic oxidation step;
- and then
- oxidizing at least said selected surface of the metal film by a second anodic oxidation step.
A method for producing a liquid crystal device comprising a first substrate having an active matrix circuit thereon, a second substrate opposed to said first substrate and having a transparent counter electrode and a light shielding film formed on said second substrate, and a liquid crystal layer disposed between said first and second substrates, said method comprising the steps of:
- forming a metal film on an entire surface of said transparent counter electrode on said second substrate, said metal film having a first area and a second area;
- anodic oxidizing said metal film to form an anodic oxide film in such a manner that said metal film is oxidized completely through its thickness in said first area and only an upper portion of said metal film is oxidized to remain a portion of the metal film not oxidized in said second area,
- wherein said anodic oxide film covers the entire surface of the transparent counter electrode as a short circuit preventing film and the metal film remaining in said second area functions as said light shielding film.
Dependencies are inferred from the claim text.