Transflective liquid crystal display panel and manufacturing method thereof

A method for manufacturing a transflective liquid crystal display panel includes providing an array substrate having a plurality of pixel regions, each of the pixel regions includes a device region, a transmission region and a reflection region defined therein; forming a first metal layer on the array substrate; patterning the first metal layer to simultaneously form a gate electrode in the device region and a plurality of metal bumps in the reflection region; forming a first insulating layer having a rough surface and covering the gate electrode and the metal bumps on the array substrate; forming a patterned semiconductor layer on the gate electrode; forming a reflective layer covering the first insulating layer and having a rough surface in the reflection region; and sequentially forming a patterned second insulating layer and a transparent pixel electrode on the array substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) panel and manufacturing method thereof, and more particularly, to a transflective LCD panel and manufacturing method thereof.

2. Description of the Prior Art

LCD panels can be classified into transmissive, reflective, and transflective types based upon the source of illumination. Along with the popularization of portable electronic products, the LCDs have to give consideration to the brightness of indoor ambient light and that of outdoor ambient light, which are different greatly from each other. Therefore the transflective LCD panel is developed to provide superior performance in abovementioned different environments.

Please refer toFIG. 1, which is a schematic drawing of a conventional transflective LCD panel. As shown inFIG. 1, a transflective LCD panel100includes an array substrate102, a color filter substrate104opposite to the array substrate102, and a liquid crystal layer106sandwiched in between the array substrate102and the color filter substrate104. The transflective LCD panel100also includes a plurality of pixel regions110, and each pixel region110includes a reflection region112and a transmission region114. The pixel regions110defined on the array substrate102respectively includes a thin film transistor (TFT)120and the TFT120is positioned in the reflection region112as shown inFIG. 1. In order to make optical path lengths of the transmitting light and the reflected light the same, the prior art further forms an organic insulating layer130covering the TFT120on the array substrate102in the reflection region112after forming the TFT120. The organic insulating layer130is patterned to form a predetermined pattern by a photomask, then a reflective layer132is formed on the organic insulating layer130. Because the predetermined pattern formed on the surface of the organic insulating layer130, the reflective layer132formed along with the profile of the predetermined pattern obtains a rough surface. Consequently, reflectivity is improved. In the transmission region114, a transparent pixel electrode140is formed and electrically connected to the TFT120through a contact hole134in the organic insulating layer130.

As mentioned above, in order to make the optical path lengths of the transmitting light and the reflected light the same, the organic insulating layer130is provided in the transflective LCD panel100to raise the reflection region112. Furthermore, a photomask is needed to define the position and the profile of the organic insulating layer130. Accordingly, the organic insulating layer130is thickened to even a half of the cell gap. In other words, the formation of the organic insulating layer130unavoidably increases the process time and the process cost. It is noteworthy that as illustration denoted in circle150, the height difference, which is caused by the organic insulating layer130, in the border between the reflection region112and the transmission region114complicates the process control when forming the pixel electrode140, even makes open line fault of the pixel electrode140. In addition, to improve the reflectivity, the photomask is employed to form the predetermined pattern in the organic insulating layer130of the conventional transflective LCD panel100, thus a rough surface is obtained after forming the reflective layer132. Accordingly, it is conceivable that fabrication of a transflective LCD panel100is more complicated and more difficult in process control.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a method for manufacturing a transflective LCD panel. The method includes providing an array substrate having a plurality of pixel regions, each of the pixel regions comprising a device region, a transmission region and a reflection region; forming a first metal layer on the array substrate; patterning the first metal layer to form a gate electrode in the device region and a plurality of metal bumps in the reflection region simultaneously; forming a first insulating layer on the array substrate, the first insulating layer covering the gate electrode and the metal bumps, and the first insulating layer having a rough surface thereby; forming a patterned semiconductor layer on the gate electrode in the device region; forming a reflective layer in the reflection region, the reflective layer covering the first insulating layer and having a rough surface thereby; and sequentially forming a patterned second insulating layer and a pixel electrode on the array substrate.

According to another aspect of the present invention, there is provided another method for manufacturing a transflective LCD panel. The method includes providing an array substrate having a plurality of pixel region, each of the pixel regions comprising a device region, a transmission region and a reflection region; forming a gate electrode on the array substrate in the device region; sequentially forming a first insulating layer and a patterned semiconductor layer on the array substrate; patterning the first insulating layer to form a plurality of bumps in the reflection region; forming a reflective layer in the reflection region, the reflective layer covering the bumps and having a rough surface thereby; and sequentially forming a patterned second insulating layer and a pixel electrode on the array substrate.

According to another aspect of the present invention, there is provided a transflective LCD panel. The transflective LCD panel includes an array substrate having a plurality of pixel regions, and each of the pixel regions comprises a device region, a transmission region and a reflection region; a TFT formed on the array substrate in the device region; a plurality of bumps formed on the array substrate in the reflection region; a reflective layer formed on the array substrate in the reflection region and having a rough surface by covering the bumps; and a pixel electrode formed on the array substrate in the transmission region and the reflection region, and the pixel electrode is electrically connected to the TFT.

DETAILED DESCRIPTION

Please refer toFIGS. 2-6, which are schematic drawings illustrating a method for manufacturing a transflective LCD panel according to a first preferred embodiment of the present invention. According to the first preferred embodiment, an array substrate200is first provided. The array substrate200is a transparent substrate that includes glass, quartz, or other transparent materials. The array substrate200includes a plurality of pixel regions210, and each pixel region210includes a device region212, a transmission region214and a reflection region216. The device region212, the transmission region214and the reflection region216are arranged in coplanar in the pixel region210. Next, a first metal layer (not shown) is formed on the array substrate200. The first metal layer can be Al, Cr, Mo, W, Ta, Cu, or alloys of the abovementioned metals. Then, as shown inFIG. 2, a first photo-etching-process (PEP) is performed to pattern the first metal layer, thus a gate electrode220is formed in the device region212and a plurality of metal bumps222is formed in reflection region216simultaneously. The metal bumps222are used to cause a rough surface of a following formed reflective layer. Accordingly, mirror effect of the reflective layer is reduced and the reflectivity is improved. In addition, though the PEP is used as the patterning method in this preferred embodiment, those skilled in the art would easily realize that the patterning method is not limited to this.

Please refer toFIG. 3. Next, a first insulating layer230, an amorphous silicon layer242and a doped silicon layer244are sequentially formed on the array substrate200. The first insulating layer230can be a single or composite layer that comprises silicon oxide (SiO), silicon nitride (SiN) or silicon oxynitride (SiON). The first insulating layer230covers the gate electrode220and the metal bumps222in the reflection region216, therefore a rough surface is obtained by covering the metal bumps222in the reflection region216. The doped silicon layer244is preferably an N-type doped silicon layer for providing Ohmic contact to a following formed source/drain. Then, a second PEP is performed to pattern the amorphous silicon layer242and the doped silicon layer244to form a patterned semiconductor layer240on the gate electrode220in the device region212.

Please refer toFIG. 4. Forming a second metal layer (not shown) on the patterned semiconductor layer240and the first insulating layer230. The second metal layer can be Al, Cr, Mo, W, Ta, Cu, or alloys of the abovementioned metals. A third PEP is performed to pattern the second metal layer, thus a metal source/drain250is formed on the patterned semiconductor layer240in the device region212and a reflective layer252is formed in the reflection region216simultaneously. It is noteworthy that because the reflective layer252covers the first insulating layer230and the metal bumps222, the reflective layer252also obtains a rough surface and the reflectivity of the reflective layer252is consequently improved. The gate electrode220, the first insulating layer230, the patterned semiconductor layer240and the source/drain250in the device region212construct a TFT290.

Please refer toFIG. 5. After forming the reflective layer252, a second insulating layer (not shown) is formed on the array substrate200and followed by performing a fourth PEP to pattern the second insulating layer. Thus, a patterned second insulating layer260covering the source/drain250in the device region212and the first insulating layer230in the transmission region214is formed as shown inFIG. 5. It is noteworthy that the patterned second insulating layer260includes at least a contact hole262for exploring a portion of the source/drain250.

Please refer toFIG. 6. After forming the patterned second insulating layer260, a pixel electrode270is formed on the array substrate200. The pixel electrode270can comprise transparent material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The pixel electrode270is formed in the transmission region214and on the reflective layer252in the reflection region216by performing a fifth PEP. And the pixel electrode270is electrically connected to the source/drain250of the TFT290through the contact hole262.

Please refer toFIG. 7, which is a schematic drawing illustrating a modification of the first preferred embodiment according to the present invention. For the sake of simplicity, portions similar to the first preferred embodiment are denoted by similar reference numerals as shown inFIGS. 2-5and the description thereof is omitted.

Please refer to bothFIG. 5andFIG. 7. After forming the patterned semiconductor layer240, a second metal layer is formed on the array substrate200. The second metal layer includes materials the same with those described in the first preferred embodiment. Then, a third PEP is performed to pattern the second metal layer to form the source/drain250on the patterned semiconductor layer240in the device region212. Simultaneously, the second metal layer in the reflection region216is selectively removed as shown inFIG. 7, or alternatively, is remained in the reflection region216as shown inFIG. 5. As mentioned above, the gate electrode220, the first insulating layer230, the patterned semiconductor layer240and the source/drain250construct the TFT290. Next, as shown inFIG. 7, the patterned second insulating layer260having the contact hole262is formed in the transmission region214and the device region212.

Please still refer toFIG. 7. After forming the patterned second insulating layer260, the pixel electrode270is formed on the array substrate200in the transmission region214and the reflection region216. The pixel electrode270is electrically connected to the source/drain250through the contact hole262. After forming the TFT290, the patterned second insulating layer260and the pixel electrode270, a third metal layer (not shown) is formed on the patterned second insulating layer260and the pixel electrode270, and is patterned to form a reflective layer280on the pixel electrode270in the reflection region216.

Please refer toFIG. 6andFIG. 7again. According to the first preferred embodiment and its modification, the metal bumps222that cause the rough surface of the reflective layer252/280are formed on the array substrate200simultaneously with the gate electrode220without influencing following processes. In other words, according to the method provided by the first preferred embodiment, the metal bumps222are formed without extra photomask. Therefore the process is simplified and the cost is reduced. It is noteworthy that the reflection region216, the device region212and transmission region214are arranged in coplanar in the pixel region210without overlapping to each other, therefore the height difference between the reflection region216and the transmission region214and the open line fault of the pixel electrode270are avoided. Furthermore, the reflective layer252is simultaneously formed with the TFT290and under the pixel electrode270as shown inFIG. 6, or alternatively formed after forming the TFT290and on the pixel electrode270as shown inFIG. 7for improving the reflectivity of the reflection region216.

Please refer toFIGS. 8-12, which are schematic drawings illustrating a method for manufacturing a transflective LCD panel according to a second preferred embodiment of the present invention. For the sake of simplicity, materials similar to the first embodiment are omitted hereinafter. According to the second preferred embodiment, an array substrate300is first provided. The array substrate300includes a plurality of pixel regions310, and each of the pixel regions310includes a device region312, a transmission region314and a reflection region316arranged in coplanar. Then, a first metal layer (not shown) is formed on the array substrate300and followed by performing a first PEP to pattern the first metal layer. Thus a gate electrode320is formed in the device region312. Please still refer toFIG. 8. A first insulating layer330, an amorphous silicon layer342and a doped silicon layer344are sequentially formed on the array substrate300and followed by patterning the amorphous silicon layer342and the doped silicon layer344. Accordingly, a patterned semiconductor layer340is formed on the gate electrode320in the device region312.

Please refer toFIG. 9. Then, patterning the first insulating layer330to form a plurality of insulating bumps332in the reflection region316. The insulating bumps332are used to cause a rough surface of a following formed reflective layer to reduce the mirror affect of the reflective layer and to improve the reflectivity.

Please refer toFIG. 10. A second metal layer (not shown) is formed on the patterned semiconductor layer340, the first insulating layer330and the insulating bumps332and followed by patterning the second metal layer. Therefore a metal source/drain350is formed on the patterned semiconductor layer340in the device region312and a reflective layer352is formed in the reflection region316simultaneously. It is noteworthy that because the reflective layer352covers the insulating bumps332, the reflective layer352formed along the profile of the insulating bumps332obtains a rough surface by covering the insulating bumps332. Consequently, reflectivity is improved. The gate electrode320, the first insulating layer330, the patterned semiconductor layer340and the source/drain350construct a TFT390.

Please refer toFIG. 11. After forming the reflective layer352, a second insulating layer (not shown) is formed on the array substrate300and followed by patterning the second insulating layer. Consequently, a patterned second insulating layer360covering the source/drain350in the device region312and the first insulating layer330in the transmission region314is formed as shown inFIG. 11. It is noteworthy that the patterned second insulating layer360includes at least a contact hole362for exploring a portion of the source/drain350.

Please refer toFIG. 12. After forming the patterned second insulating layer360, a pixel electrode370is formed on the array substrate300in the transmission region314and on the reflective layer352in the reflection region316. The pixel electrode370is electrically connected to the source/drain350through the contact hole362.

Please refer toFIGS. 13-14, which are schematic drawings illustrating a modification of the second preferred embodiment according to the present invention. For the sake of simplicity, portions similar to the second embodiment are denoted by similar reference numerals as shown inFIGS. 8-12and the description thereof is omitted.

Please refer toFIG. 13. After forming the patterned semiconductor layer340, a second metal layer is formed on the array substrate300and followed by patterning the second metal layer to form a metal source/drain350on the patterned semiconductor layer340in the device region312. The second metal layer in the reflection region316is selectively removed as shown inFIG. 13, or alternatively is remained in the reflection region316as shown inFIG. 10. As mentioned above, the gate electrode320, the first insulating layer330, the patterned semiconductor layer340and the source/drain350construct the TFT390. And after forming the source/drain350, that is, after forming the TFT390, a second insulating layer359is formed on the array substrate300.

Please refer toFIG. 14. Since the etching rates between the first insulating layer330and the second insulating layer359are similar, the first insulating layer330in the reflection region316is also patterned during patterning the second insulating layer359in the device region312and the transmission region314. Thus a plurality of insulating bumps364is formed. And after patterning the second insulating layer359and forming the insulating bumps364, the pixel electrode370is formed on the array substrate300in the transmission region314and the reflection region316. The pixel electrode370is electrically connected to the source/drain350through the contact hole362. Then, a third metal layer (not shown) is formed on the insulating bumps364and the pixel electrode370and followed by patterning the third metal layer. Consequently, a reflective layer380is formed on the pixel electrode370in the reflection region316.

Please refer to bothFIG. 12andFIG. 14. According to the second preferred embodiment and its modification, the insulating bumps332that cause the rough surface of the reflective layer352/380are formed on the array substrate300by patterning the first insulating layer330with an extra photomask. Additionally, the insulating bumps364also can be formed by patterning the first insulating layer330simultaneously with patterning the second insulating layer359without extra photomask. Therefore the process is simplified and the cost is reduced. It is noteworthy that the reflection region316, the device region312and transmission region314are arranged in coplanar in the pixel region310without overlapping to each other, therefore the height difference between the reflection region316and the transmission region314and the open line fault of the pixel electrode370are avoided. Furthermore, the reflective layer352is simultaneously formed with the TFT390and under the pixel electrode370as shown inFIG. 12, or alternatively formed after forming the TFT390and on the pixel electrode370as shown inFIG. 14for improving the reflectivity of the reflection region316.

As mentioned above, according to the transflective LCD panel and manufacturing method thereof provided by the present invention, the bumps are formed without introducing any extra photomask. Therefore the process is simplified and the cost is reduced. Furthermore, since the reflection region, the device region and transmission region are arranged in coplanar in the pixel region without overlapping to each other, the height difference between the reflection region and the transmission region and the open line fault of the pixel electrode are avoided. In addition, transflective LCD panel and manufacturing method thereof provided by the present invention is not limited to a dual-cell gap or single-cell gap transflective LCD panel.