Sealant region pattern for liquid crystal display and method for fabricating the same

The present invention relates to a display and, more particularly, to a sealant region pattern and fabrication methods thereof.

TFT LCD devices can suffer from degradation related to ambient environmental conditions such as moisture which may lead to performance loss, operational instability, poor color/emission accuracy, and shortened operational life. Specifically, water can cause crystallization and formation of organic solids, electrochemical reactions at the electrode-organic layer interface, corrosion of metals and migration of ionic species. To minimize such degradation, a TFT LCD device must be properly encapsulated to prevent moisture migration. Typical encapsulation methods utilize a color filter substrate covering organic polymer areas with an adhesive sealant.

However, conventional encapsulation methods suffer from problems such as sealant peeling, uneven cell gaps, and formation of voids in the sealant regions during assembly.

An improved method of encapsulating a LCD apparatus is thus called for.

A method for a sealant region pattern of a liquid crystal display apparatus is disclosed. The methods comprise providing a first substrate and a second substrate opposite thereto, forming a predetermined material layer on the first substrate, forming an organic material pattern layer having a saw tooth opening on the predetermined material layer. The saw tooth opening to expose the surface of the predetermined material layer underneath and the surface of the predetermined material layer and the sidewall of the organic material pattern layer form a predetermined angle.

A sealant region pattern is also disclosed. A saw tooth opening is formed in an organic material layer on a first substrate to expose a predetermined material layer underneath. The surface of the predetermined material layer and the sidewall of the organic material pattern layer form a predetermined angle.

The present invention reduces reliability and integrity problems encountered in conventional methods. Peeling of sealant, uneven cell gaps, and formation of voids in sealant regions during assembly are all reduced.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

The present invention can be more fully understood by reading the subsequent detailed description and examples with reference made to the accompanying drawings, wherein:

FIG. 1A is a top view of a sealant region for a thin film transistor-liquid crystal display (TFT-LCD) apparatus according to a comparative example.

FIG. 1B is a top view of a portion of the sealant region shown in FIG. 1A .

FIG. 1C is a cross-section of the TFT-LCD shown in FIG. 1B along the plane defined by horizontal dotted line AA′.

FIGS. 2A to 2C are cross-sections of fabrication of a TFT-LCD according to an embodiment of the present invention.

Comparative Example

FIG. 1A is a top view of a sealant region for a thin film transistor-liquid crystal display (TFT-LCD) according to a comparative example. As shown in FIG. 1A , the TFT-LCD apparatus comprises a TFT array substrate 132 , saw tooth openings 134 , a sealant region 136 , and a color filter substrate 140 . Sealant 146 shown in FIG. 1C is applied in the openings, forming a sealant region 136 for attachment of the TFT array substrate 132 to the color filter substrate 140 .

FIG. 1B is a top view of a portion 138 of the sealant region shown in FIG. 1A . The width of sealant region 136 is marked by distance m confined by the two vertical lines. The width w 1 of the openings equals width w 2 of the openings. The sealant 146 shown in FIG. 1C can be evenly distributed on both sides of a central axis S of the sealant region 136 . In other examples, the width w 1 may not equal the width w 2 .

A fabrication method of the described sealant region pattern comprises the following steps.

As shown in FIG. 1C , a TFT array substrate 132 is provided. A predetermined material layer such as a silicon nitride layer 142 is formed on the TFT array substrate 132 , serving as a passivation layer.

An organic material layer 144 is formed on the silicon nitride layer 142 . The organic material layer 144 is patterned by lithography.

Saw tooth openings 134 shown in FIG. 1B are formed in the organic material layer 144 by etching, and sealant 146 is placed therein.

Voids or bubbles 150 formed during application of the sealant 146 occur due to angle θ between sidewall of saw tooth openings 134 and the surface of silicon nitride layer 142 exceeding 60 degrees.

A method of forming a sealant region pattern for a liquid crystal display is disclosed.

In FIGS. 2A and 2C , a TFT array substrate 232 and a color filter substrate 260 opposite thereto are provided. A predetermined material layer such as a silicon nitride layer 242 is formed on the TFT array substrate 232 , serving as a passivation layer. Alternatively, the passivation layer can comprise silicon oxynitride, silicon oxide, organic dielectric layer, or a combination thereof. The predetermined material layer may further comprise Mo, Ti, Al, Ta, metal oxide, metal nitride, or a combination thereof, serving as a metal electrode layer.

An organic material layer 244 is formed on the silicon nitride layer 242 . The organic material layer 244 is patterned by lithography, exposed to UV light 250 through a half-tone mask 248 with a predetermined pattern thereon. The predetermined pattern can comprise various openings of different size, providing various local transmittances. Accordingly, the organic material layer 244 is tapered after subsequent development and etching. The organic material layer 244 comprises polymethyl methacrylate (PMMA), photosensitive-methylsilsesquiazane (PS-MSZ), or the like.

In FIG. 2B , saw tooth opening 234 are formed in the organic material layer 244 by etching, similar to saw tooth opening 134 shown in FIG. 1B . The half-tone mask 248 can comprise a gray-tone or slit-pattern mask. Preferably, no etching is performed when using photosensitive low-k organic materials in the organic material layer 244 .

An organic material pattern layer 244 a is formed on the silicon nitride layer 242 after etching. Portions of the silicon nitride layer 242 are exposed by the saw tooth opening 234 in the organic material pattern layer 244 a . Moreover, the sidewall 244 b of saw tooth opening 234 and the surface 242 a of silicon nitride layer 242 form a predetermined angle α. The organic material pattern layer 244 a comprises a plurality of segments 245 adjacent to the saw-tooth opening 234 . The thickness of segments 245 increases with distance from the saw tooth opening.

The predetermined angle α is substantially less than 60 degree. In other embodiments, the predetermined angle α ranges from about 20 degree to about 60 degree, or about 50 degree to about 60 degree, or about 10 degree to about 20 degree, or about 30 degree to about 40 degree, or about 40 degree to about 50 degree, preferably about 20 degree to about 30 degree.

In FIG. 2C , a predetermined sealant 246 is placed in the saw tooth opening 234 or in the corresponding position of the saw tooth opening 234 of the TFT-LCD substrate 232 for attaching the color filter substrate 260 with the TFT-LCD substrate 232 .

With predetermined angle α, air exhausts easily via the tapered profile of the saw tooth opening 234 during application of sealant, avoiding formation of voids or bubbles in the sealant.

While the present invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the present invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation to encompass all such modifications and similar arrangements.