Active matrix substrate having column spacers integral with protective layer and process for fabrication thereof
View Patent ↗An active matrix substrate forms a liquid crystal display panel together with a counter substrate and liquid crystal filling a gap therebetween, and color filters are covered with an overcoat layer of photo-sensitive acrylic resin, wherein column spacers of the photo-sensitive acrylic resin project from the overcoat layer so that the column spacers are hardly separated from the overcoat layer in a rubbing for producing an orientation layer.
1. A process for fabricating an active matrix substrate, comprising:
preparing a plate having an upper surface;
laminating a multiple layered device structure on said upper surface for providing conductive layers forming parts of pixels;
laminating an optically modulating structure on said multiple layered device structure for providing color filters to said parts of said pixels;
covering said optically modulating structure with a photo-sensitive layer;
exposing said photo-sensitive layer to an image-carrying light for producing at least two portions different in solubility to a developer;
treating said photo-sensitive layer with said developer to form a protective layer having at least one protrusion projecting from a remaining portion thereof; and
completing said active matrix substrate,
wherein said covering said optically modulating structure comprises:
forming a first photo-sensitive sub-layer of a first kind of photo-sensitive material over said optically modulating structure; and
forming a second photo-sensitive sub-layer of a second kind of photo-sensitive material opposite in photo-sensitized property to said first kind of photo-sensitive material on said first photo-sensitive sub-layer, a mixture between said first kind of photo-sensitive material and said second photo-sensitive material being produced at the boundary between said first photo-sensitive sub-layer and said second photo-sensitive sub-layer.
2. The process as set forth in claim 1 , wherein said image-carrying light is fallen onto said second photo sensitive sub-layer in said exposing said photo-sensitive layer for producing one of said at least two portions in said second photo-sensitive sub layer, and said second photo-sensitive sub-layer is formed into said protrusion in said treating said photo-sensitive layer.
3. The process as set forth in claim 2 , further comprising:
exposing said first photo-sensitive sub-layer to another image-carrying light for producing another portion different in solubility to another developer from a remaining portion in said first photo-sensitive sub-layer after said step treating said photo-sensitive layer; and
treating said first photo-sensitive sub-layer and the layer of said mixture with said another developer for producing an opening in said first photo-sensitive sub-layer and said layer of said mixture between said exposing said first photo-sensitive sub-layer to another image carrying light and said completing said active matrix substrate.
4. The process as set forth in claim 1 , wherein said first photo-sensitive material comprises a positive photo-sensitive resin and said second photo-sensitive material comprises a negative photosensitive resin.
5. The process as set forth in claim 1 , wherein said at least one protrusion projects from said protective layer between adjacent pixel electrodes.
6. The process as set forth in claim 1 , wherein said at least one protrusion is formed over a thin film field effect transistor formed on said active matrix substrate.