1. Field of the Invention
The present invention relates to a component array substrate and a fabricating method thereof. More particularly, the present invention relates to an active component array substrate and a fabricating method thereof.
2. Description of Related Art
The thin film transistor liquid crystal display (TFT-LCD) mainly comprises a thin film transistor array substrate, a color filter array substrate, and a liquid crystal layer. The thin film transistor array substrate comprises a plurality of thin film transistors in arrays and pixel electrodes arranged corresponding to each of the thin film transistors. The thin film transistors are used as switches of the liquid crystal display unit. Furthermore, in order to control an individual pixel unit, a specific pixel is selected by the scan lines and the data lines, and an appropriate operating voltage is applied to display the display data corresponding to the specific pixel. Moreover, a part of the area of the pixel electrode described above generally covers the scan lines or the common lines to form a storage capacitor. In conventional arts, common storage capacitors are classified into two architectures, namely metal-insulator-metal (MIM) and metal-insulator-ITO (MII). The structures of the two architectures of storage capacitors will be described in detail below.
With the increase of the panel size, voltage waveform delay and distortion often occur in signals transmitted through scan lines due to an RC effect. In this case, a part of the pixel electrodes receives wrong data signals due to insufficient charge or feed-through voltage, so nonuniform brightness and flickers occur on two sides of the image. Therefore, the storage capacitance value Cst has to be adjusted to resolve the problems described above. However, in conventional thin film transistor array substrates, in order to increase the storage capacitance value Cst without affecting the aperture ratio, the total thickness of the gate insulation layer 210 and/or the protection layer 220 must be directly reduced. Particularly, if the total thickness of the gate insulation layer 210 and/or the protection layer 220 is directly reduced, the component reliability of the thin film transistors may be degraded.
Accordingly, an object of the present invention is to provide a method for fabricating an active component array substrate, wherein an active component array substrate with more than two types of storage capacitors may be formed.
Another object of the present invention is to provide an active component array substrate having more than two types of storage capacitors.
In order to achieve the aforementioned and or other objects, the present invention provides a method for fabricating an active component array substrate. First, a substrate is provided. A plurality of scan lines, a plurality of data lines, a plurality of active components, a plurality of common lines, a first dielectric layer, and a second dielectric layer are formed on the substrate, wherein the scan lines and the data lines define a plurality of pixel regions on the substrate, and the common lines are arranged on the substrate. Each of the active components is respectively controlled by corresponding scan line and data line. The first dielectric layer extends from each active component to above the pixel regions, and the second dielectric region covers the scan lines, the data lines, the common lines, the active components, and the first dielectric layer. Next, a half tone mask is provided to remove a portion of the second dielectric layer, such that a plurality of contact windows is formed. A recess is formed above the common line on a portion of each pixel region. Then, a pixel electrode is formed on each pixel region. The pixel electrode is coupled to the common line to form a storage capacitor. Each of the pixel electrodes is electrically connected to the active components via corresponding contact windows. The storage capacitors are classified into more than two types.
In one embodiment of the present invention, the overlapping areas of the recess and the common lines above each pixel region is gradually reduced from one end of the common lines to the other end.
In one embodiment of the present invention, each of the common lines has a plurality of branches extending outward from the edges of two sides and being parallel to the data lines.
In one embodiment of the present invention, the step of forming the contact windows and recesses includes forming a patterned photoresist layer on the second dielectric layer by using a half tone mask; removing a portion of the second dielectric to form the contact windows and the recesses above a portion of the common lines using the patterned photoresist layer as the mask; and removing the patterned photoresist layer.
In one embodiment of the present invention, the step of forming the recesses described above includes removing a portion of the thickness of the second dielectric layer above a portion of the common lines.
In one embodiment of the present invention, the step of forming the recesses described above includes completely removing the second dielectric layer above a portion of the common lines.
In one embodiment of the present invention, the step of forming the recesses described above includes completely removing the second dielectric layer above a portion of the common lines and removing a portion of the thickness of the first dielectric layer.
In order to achieve the aforementioned and or other objects, the present invention provides an active component array substrate fabricated using the method described above. The active component array substrate comprises a substrate, a plurality of scan lines, a plurality of active components, a plurality of pixel electrodes, a first dielectric layer, and a second dielectric layer. The scan lines, the data lines, and the common lines are arranged on the substrate, and the scan lines and the data lines define a plurality of pixel regions on the substrate. Furthermore, the common lines and the scan lines are alternately arranged on the substrate. The active components are respectively arranged on the pixel regions. Each of the active components is controlled by corresponding scan line and data line. The pixel electrodes are respectively arranged on the pixel regions. Each of the pixel electrodes is electrically connected to corresponding active components, and is coupled to the corresponding common line to form a storage capacitor. The first dielectric layer extends from each component to below the pixel electrodes. The second dielectric layer covers the active components, and extends from above the active components to below the pixel electrodes. The second dielectric layer has a plurality of recesses located above a part of the common lines. Moreover, the storage capacitors described above are classified into more than two types, and the minimum distance between each recess and the common lines is less than the total thickness of the first dielectric layer and the second dielectric layer in corresponding active components.
In one embodiment of the present invention, the overlapping areas of the recess and the common lines above each pixel region is gradually reduced from one end of the common lines to the other end.
In one embodiment of the present invention, each of the common lines has a plurality of branches extending outward from the edges of two sides and are arranged parallel to the data lines.
In one embodiment of the present invention, the minimum distance between the recesses and the common lines is greater than the thickness of the first dielectric layer in the active components.
In one embodiment of the present invention, the minimum distance between the recesses and the common lines is equal to the thickness of the first dielectric layer in the active components.
In one embodiment of the present invention, the minimum distance between the recesses and the common lines is less than the thickness of the first dielectric layer in the active components.
Accordingly, the present invention employs the half tone mask to simultaneously form the contact windows and the recesses. Therefore, more than two types of storage capacitors are formed on the same substrate by adjusting the depth of the recesses or the overlapping areas of the recesses and the pixel electrodes, such that the RC delay effect of large-size panels is reduced or eliminated.
In order to make aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
The present invention employs a half tone mask to simultaneously form the contact windows and the recesses. Since the pixel electrodes cover the recesses, storage capacitors are formed by coupling the pixel electrodes and the common lines. More than two types of storage capacitors are formed on the same substrate by adjusting the depth of the recesses or the overlapping areas of the recesses and the pixel electrodes. Therefore, according to the present invention, the electrical performance of a large-size active component array substrates can be improved. Several embodiments will be described below to illustrate the present invention, which are not intended to limit the present invention. Those skilled in the art can make appropriate modifications to the following embodiments without departing from the spirit of the present invention, and such modifications are construed to be within the scope of the present invention.
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It should be noted that only three masks are used to form the structure shown in
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As the half tone mask 310 comprises a non-transmissive area 310a, a partially transmissive area 310b and a completely transmissive area 310c, the transmittance of the partially transmissive area 310b is between that of the non-transmissive area 310a and the completely transmissive area 310c, so the thickness of the patterned photoresist layer 320 on various areas is different from one another. For example, the patterned photoresist layer 320 exposes a portion of the surface of the second dielectric layer 480 on the sources/drains 456 and a portion of the surface of the second dielectric layer 480 on the pads 460.
It should be noted that as the position of the partially transmissive area 310b corresponds to the common lines 440, the thickness of the patterned photoresist layer 320 above the common lines 440 is less than that of other portions of the patterned photoresist layer 320. In addition, the half tone mask 310 of the embodiment may also include a transmittance modulation mask or other suitable type of mask for forming a patterned photoresist layer with different thickness (as shown in
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As described in the above processes, the depths of the recesses 480c are determined by the thickness of the patterned photoresist layer 320 above the common lines 440. In addition, the depths of the recesses 480c or the overlapping areas of the recesses 480c and the pixel electrodes 490a result in different storage capacitors. In other words, the active component array substrate fabricated according to the embodiment can comprise more than two types of storage capacitors.
The pixel electrodes 490a are respectively arranged on the pixel regions 410a. Each of the pixel electrodes 490a is electrically connected to corresponding active component 450 via the contact window 480a. And, each of the pixel electrodes 490a is coupled to its corresponding common line 440 to form a storage capacitor. Furthermore, the first dielectric layer 470 extends from each component 450 to below the pixel electrodes 490a. The second dielectric layer 480 covers the active components 450, and extends from above the active components 450 to below the pixel electrodes 490a. The second dielectric layer 480 has a plurality of recesses 480c located above a part of the common lines 440. In the embodiment, all storage capacitors are divided into at least two types. In addition, the minimum distance between various recesses 480c and the common lines 440 is less than the total thickness of the first dielectric layer 470 and the second dielectric layer 480.
It should be noted that when the overlapping areas of the recesses 480c and the pixel electrodes 490a above each pixel region 410a vary, the capacitance of the storage capacitors on each pixel region 410a changes accordingly. Therefore, when the size of the active component array substrate 400 becomes larger, the capacitance of the storage capacitors on various pixel regions 410a gradually becomes high from the signal input end of the scan lines 420 to the other end, thus reducing or eliminating the RC delay effect. In other words, the overlapping areas of the recesses 480c and the common lines 440 above each pixel region 410a are gradually reduced from one end of the common lines 440 to the other end. However, the storage capacitors on various pixel regions can be distributed in other forms to reduce or eliminate the RC delay effect.
Moreover, the present invention can provide the active component array substrate 400 with more than two types of storage capacitors without requiring additional process steps. In addition, the present invention can provide multiple types of storage capacitors without affecting the aperture ratio.
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Accordingly, the active component array substrate and the method for fabricating the same according to the present invention include at least the following advantages.
1. Compared to the conventional arts, the present invention employs the half tone mask to simultaneously form the contact windows and the recesses, and the pixel electrodes cover the recesses. Therefore, more than two types of storage capacitors can be formed on the same substrate by adjusting the depths of the recesses or the overlapping areas of the recesses and the pixel electrodes, such that the RC delay effect of large size panels is reduced or eliminated.
2. The storage capacitance value on a unit area is increased without requiring any additional masks.
3. The storage capacitors with a higher storage capacitance value can be formed without changing the aperture ratio.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.