Patent Publication Number: US-2013250221-A1

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of and claims the priority benefit of U.S. application Ser. No. 12/556,855, filed on Sep. 10, 2009, now pending. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical device and a manufacturing method thereof, and more particularly to a display device and a manufacturing method thereof. 
     2. Description of Related Art 
     A liquid crystal on silicon (LCOS) panel is a display panel manufactured by using a silicon wafer as a substrate. Here, a metal-oxide-semiconductor (MOS) transistor is utilized to replace a thin film transistor (TFT) disposed on a glass substrate in a conventional transmissive LCD panel. The LCOS panel is a reflective display panel, and a pixel electrode thereof is manufactured with a non-light-transmissive metal material. Moreover, since the metal pixel electrode almost covers the entire pixel area, when comparing to a transparent pixel electrode of the conventional transmissive LC panel only capable of covering a relatively small portion of the pixel area, the LCOS panel can utilize a light source more efficiently to enhance a brightness of a display frame. 
     The LCOS panel is mainly constituted by the silicon substrate, a patterned metal electrode layer, and a plurality of optical film layers such as, an alignment layer, a liquid crystal layer, an alignment layer, an indium tin oxide (ITO) layer, and a glass substrate sequentially disposed on the silicon substrate. Herein, the patterned metal electrode layer is configured to constitute the pixel electrodes and the ITO layer is configured to constitute the transparent electrodes. A light from the light source passes through the glass substrate, the ITO layer, the alignment layer, the liquid crystal layer, the alignment layer sequentially to transmit to the patterned metal electrode layer. The patterned metal electrode layer reflects the light, so that the light passes through the alignment layer, the liquid crystal layer, the alignment layer, the ITO layer, and the glass substrate sequentially to transmit to the external environment. 
     Generally, an assembly of the LCOS panel usually adopts a sealant to adhere the silicon substrate and the glass substrate. The sealant is directly disposed on opposite surfaces of two alignment layers and surrounds the liquid crystal layer. Since a material of the alignment layer most adopts silicon dioxide having a loose molecular structure, the assembled LCOS panel is easily infiltrated by moisture into the liquid crystal layer via the alignment layer. Hence, not only is the aging of devices in the LCOS panel increased to further cause a decrease in the lifetime of devices manufactured, but the display quality and reliability of the LCOS panel is also affected. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a manufacturing method of a display device capable of solving a conventional problem of moisture invading into a liquid crystal layer via an alignment layer, thereby enhancing a manufacturing yield rate. 
     The present invention is directed to display device having superior reliability and display quality. 
     The present invention further provides a manufacturing method of a display device. Firstly, an active device array substrate having an active surface is provided. Next, a first patterned photoresist layer is formed on the active surface. Then, a first alignment layer is obliquely vapor-deposited on the active surface and the first patterned photoresist layer, wherein the active surface comprises at least a first undeposited area located beside an edge of the first patterned photoresist layer. A first alignment unit is formed by removing the first patterned photoresist layer and a portion of the first alignment layer located thereon. A sealant is directly formed on the active surface of the active device array substrate and surrounds the first alignment unit. An opposite substrate having a light transmissive surface is provided. After that, the active device array substrate and the opposite substrate are assembled. 
     The present invention is further directed to a display device including an active device array substrate, an opposite substrate, at least a first alignment unit, at least a second alignment unit, a liquid crystal layer, and a sealant. The active device array substrate has an active surface. The opposite substrate is disposed above the active device array substrate and includes a light transmissive surface. Additionally, the active surface and the light transmissive surface face each other. The first alignment unit is disposed on the active device array substrate and located on the active surface. The second alignment unit is disposed on the opposite substrate and located on the light transmissive surface. Here, the first alignment unit aligns with the second alignment unit. The liquid crystal layer is disposed between the first alignment unit and the second alignment unit. The sealant directly connects the active surface of the active device array substrate and the light transmissive surface of the opposite substrate, and surrounds peripherals of the liquid crystal layer, the first alignment unit, and the second alignment unit. 
     In light of the foregoing, in the manufacturing method of the display device of the embodiment of the present invention, the oblique vapor-deposition is adopted in corporation with using the photoresist remover to remove the patterned photoresist layer and a portion of the alignment layer located on the patterned photoresist layer from the edge. Therefore, the alignment units are manufactured on the active device array substrate and the opposite substrate. Consequently, when the active device array substrate and the opposite substrate are connected, the sealant surrounds the peripheral of the liquid crystal layer and the alignment units. That is, the sealant is located on the active device array substrate and the opposite substrate and surrounds the liquid crystal layer and the alignment units, thereby preventing the conventional problem of moisture invading into the liquid crystal layer via the alignment layer and also enhancing the manufacturing yield rate. Hence, the display device of the embodiment of the present invention has superior display quality. 
     In order to make the aforementioned and other features and advantages of the present invention more comprehensible, several embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic cross-sectional view of a display device according to an embodiment of the present invention. 
         FIG. 2A  through  FIG. 2J  are schematic cross-sectional views of a manufacturing method of a display device according to an embodiment of the present invention. 
         FIG. 3A  through  FIG. 3C  are cross-sectional views of a partial manufacturing method of a display device according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a schematic cross-sectional view of a display device according to an embodiment of the present invention. Referring to  FIG. 1 , an display device  100  of the present embodiment includes an active device array substrate  200 , an opposite substrate  300 , at least a first alignment unit  400  (only one is schematically shown in  FIG. 1  for example), at least a second alignment unit  500  (only one is schematically shown in  FIG. 1  for example), a liquid crystal layer  600 , and a sealant  700 . The display device  100  is a reflective type liquid crystal panel, for example. 
     The active device array substrate  200  includes a silicon substrate  210  and a pixel electrode  220 . The silicon substrate  210  includes an active surface  212  and a plurality of active devices  214 . The pixel electrode  220  is disposed on the silicon substrate  210  and located on the active surface  212 . In the present embodiment, the active devices  214  are arranged in an array on the active surface  212  of the silicon substrate  210 . The active devices  214  are transistors or other suitable active devices, for instance. A material of the pixel electrode  220  is aluminum, for example. In addition, the first alignment unit  400  is disposed on the active device array substrate  200  and located on the active surface  212  of the silicon substrate  210 . Here, a material of the first alignment unit  400  is silicon dioxide, for example. Specifically, the first alignment unit  400  is disposed on the silicon substrate  210  and covers the pixel electrode  220 . 
     The opposite substrate  300  is disposed above the active device array substrate  200  and includes a light transmissive substrate  310  and a light transmissive electrode  320 . The opposite substrate  310  has a light transmissive surface  312  and the light transmissive electrode  320  is disposed on the light transmissive substrate  310  and located at the light transmissive surface  312 . In the present embodiment, the active surface  212  of the silicon substrate  210  and the light transmissive surface  312  of the light transmissive substrate  310  face each other. The light transmissive substrate  310  is a fused silica substrate, a glass substrate, or a light transmissive substrate of other materials, for instance. A material of the light transmissive electrode  320  is indium tin oxide (ITO), indium zinc oxide (IZO), or other transparent conductive materials. Moreover, the second alignment unit  500  is disposed on the opposite substrate  300  and located on the light transmissive surface  312  of the light transmissive substrate  310 . The first alignment unit  400  aligns with the second alignment unit  500 . A material of the second alignment unit  500  is silicon dioxide, for example. Specifically, the second alignment unit  500  is disposed on the light transmissive substrate  310  and covers the light transmissive electrode  320 . 
     The liquid crystal layer  600  is disposed between the first alignment unit  400  and the second alignment unit  500 . Here, the first alignment unit  400  disposed between the liquid crystal layer  600  and the active device array substrate  200  may vertically align the liquid crystal layer  600 . The second alignment unit  500  disposed between the liquid crystal layer  600  and the opposite substrate  300  may vertically align the liquid crystal layer  600 . 
     In the present embodiment, the sealant  700  is disposed on the active device array substrate  200  and the opposite substrate  300 , and directly connects with each other. Further, the sealant  700  is surrounds the liquid crystal layer  600 , the first alignment unit  400 , and the second alignment unit  500 . Therefore, external moisture cannot infiltrate into the display device  100 . In other words, the sealant  700  effectively blocks external moisture, and thereby solving the conventional problem of moisture invading into the liquid crystal layer. Consequently, the display device  100  of the present embodiment has superior display quality. 
       FIG. 2A  through  FIG. 2J  are schematic cross-sectional views of a manufacturing method of a display device according to an embodiment of the present invention. In order to facilitate illustration,  FIGS. 2A to 2C  and  FIGS. 2G to 2J  omit illustrations of the active devices  214 . Referring to  FIG. 2A , according to a manufacturing method of the display device in the present embodiment, an active device array substrate  200  (i.e. a substrate) is first provided. Here, the active device array substrate  200  includes a silicon substrate  210  having an active surface  212  (i.e. an upper surface) and a pixel electrode  220 . The pixel electrode  220  is disposed on the silicon substrate  210  and located at the active surface  212 . 
     Next, referring to  FIG. 2A , a first patterned photoresist layer  230  is formed on a first photoresist-disposed area  212   a  of the active surface  212  of the silicon substrate  210 . Specifically, a first photoresist layer (not shown) is formed and covered the active surface  212  of the silicon substrate  210  firstly. Thereafter, the first patterned photoresist layer  230  is formed by an exposure process and a developing process. 
     Afterward, referring to  FIG. 2B , a first alignment layer  410  is obliquely vapor-deposited on the active surface  212  and the first patterned photoresist layer  230 . In the present embodiment, a first vapor-depositing source  800   a  is provided above the active device array substrate  200 . Subsequently, the first alignment layer  410  is obliquely vapor-deposited on the active surface  212  and the first patterned photoresist layer  230  in a first vapor-depositing direction d 1 . Herein, the first vapor-depositing direction d 1  tilts relative to the active surface  212 . In this embodiment, the first vapor-depositing direction d 1  and the active surface  212  have an included angle a 1 , and this included angle a 1  is between 25 and 35 degrees. The active surface  212  has at least a first undeposited area  212   b  located beside an edge of the first patterned photoresist layer  230 . The first alignment layer  410  does not cover the first undeposited area  212   b . Particularly, in the present embodiment, the first alignment layer  410  is aligned while the oblique vapor-deposition is performed. A material of the first alignment layer  410  is, for example, silicon dioxide. 
     Moreover, referring to  FIG. 2C , the first patterned photoresist layer  230  and a portion of the first alignment layer  410  located on the first patterned photoresist layer  230  are removed by using a first photoresist remover (not shown) to form at least a first alignment unit  400  (three units are shown in  FIG. 2C  for example) and expose the first photoresist-disposed area  212   a . In specific, in the present embodiment, a lift off method is adopted, that is to soak the active device array substrate  200 , the first patterned photoresist layer  230  formed thereon, and the first alignment layer  410  in the first photoresist remover. Consequently, the first photoresist remover removes the first patterned photoresist layer  230  and the first alignment layer  410  formed thereon to form the first alignment unit  400 . Here, the first photoresist remover is acetone, for instance. Up to this point, the first alignment unit  400  has been formed on the active device array substrate  200  and the manufacture of an alignment substrate is completed. 
     In the manufacturing method of the alignment substrate of the present embodiment, the first alignment unit  400  is selectively formed on the active device array substrate  200 , and the first alignment layer  410  is aligned simultaneously while being obliquely vapor-deposited. Therefore, the manufacturing steps are simplified to enhance an efficiency of the manufacturing method for manufacturing alignment substrates. 
     Subsequently, referring to  FIG. 2D , an opposite substrate  300  (i.e. another substrate) is provided. The opposite substrate  300  includes a light transmissive substrate  310  and a light transmissive electrode  320 . The light transmissive substrate  310  has a light transmissive surface  312  (i.e. another upper surface) and the light transmissive electrode  320  is disposed on the light transmissive substrate  310  and located at the light transmissive surface  312 . 
     Next, referring to  FIG. 2D , a second patterned photoresist layer  330  is formed on a second photoresist-disposed area  312   a  of the light transmissive surface  312 . Specifically, a second photoresist layer (not shown) is formed and covered the light transmissive surface  312  firstly. Thereafter, the second patterned photoresist layer  330  is formed on the second photoresist-disposed area  312   a  of the light transmissive surface  312  by the exposure process and the developing process. 
     Afterward, referring to  FIG. 2E , a second alignment layer  510  is obliquely vapor-deposited on the light transmissive surface  312  and the second patterned photoresist layer  330 . As previously illustrated in  FIG. 2B , the light transmissive surface  312  has at least a second undeposited area  312   b  located beside an edge of the second patterned photoresist layer  330 . The second alignment layer  510  does not cover the second undeposited area  312   b . In the present embodiment, a second vapor-depositing source  800   b  is provided on the opposite substrate  300 . Subsequently, the second alignment layer  510  is obliquely vapor-deposited on the light transmissive surface  312  and the second patterned photoresist layer  330  in a second vapor-depositing direction d 2 . Herein, the second vapor-depositing direction d 2  tilts relative to the light transmissive surface  312 . In this embodiment, the second vapor-depositing direction d 2  and the light transmissive surface  312  have an included angle a 2 , and this included angle a 2  is between 25 and 35 degrees. Particularly, in the present embodiment, the second alignment layer  510  is aligned simultaneously while the oblique vapor-deposition is performed. A material of the second alignment layer  510  is, for example, silicon dioxide. 
     Furthermore, referring to  FIG. 2F , the second patterned photoresist layer  330  and a portion of the second alignment layer  510  located on the second patterned photoresist layer  330  are removed from the second edge  332  by using a second photoresist remover (not shown) to form at least a second alignment unit  500  (three units are shown in  FIG. 2F  for example) and expose the second photoresist-disposed area  312   a . As previously illustrated in  FIG. 2C , the second alignment unit  500  has been formed on the opposite substrate  300  and the manufacture of another alignment substrate is completed. 
     Later, referring to  FIG. 2G , at least a sealant  700  is directly formed on the active surface  212  of the active device array substrate  200  and surrounds the peripheral of the first alignment unit  400 . The sealant  700  and the first alignment unit  400  form at least a containing recess  612  for filling liquid crystal. It should be illustrated that the location at which the sealant  700  has formed is not limited in the present invention. In the present embodiment, the sealant  700  is formed on the active device array substrate  200 . However, in other embodiments, the sealant  700  may be directly formed on the light transmissive surface  312  of the opposite substrate  300  and surrounds the peripheral of the second alignment unit  500 . Hence, the sealant  700  illustrated in  FIG. 2G  is merely exemplary and the present embodiment is not limited thereto. 
     Next, referring to  FIG. 2H , a one-drop filling process is performed so as to fill a liquid crystal material  610  into the containing recess  612 . Thereafter, referring to  FIG. 2I , the active device array substrate  200  and the opposite substrate  300  are assembled for packing the liquid crystal material  610  therebetween, so that the active surface  212  and the light transmissive surface  312  face each other and the first alignment unit  400  aligns with the second alignment unit  500 . 
     After the active device array substrate  200  and the opposite substrate  300  are assembled, referring to  FIGS. 2I and 2J  simultaneously, a cutting process is performed along the first photoresist-disposed area  212   a  and the second photoresist-disposed area  312   a  to form a plurality of display devices  100  (only one display device is shown in  FIG. 2J  for illustration). Then, the manufacture of the display device  100  is completed. 
     It should be noted that in the present embodiment, the liquid crystal material  610  is first filled into the containing recess  612 , and then the active device array substrate  200  and the opposite substrate  300  are assembled and cut. However, in other embodiments, the active device array substrate  200  and the opposite substrate  300  are assembled before liquid crystal filling Referring to  FIG. 3A through 3C , the sealant  700 , the first alignment unit  400 , and the second alignment unit  500  form at least a liquid crystal containing space  614  (shown as a plurality of liquid crystal containing spaces in  FIG. 3A ) after assembling. The liquid crystal material  610  is injected into the liquid crystal containing space  614  via a liquid crystal injection entrance  616  preserved in the formation of the sealant  700 . Afterwards, a cutting process is performed to forming a plurality of display devices  100 ′. 
     In summary, in the manufacturing method of the alignment substrate of the embodiment in the present invention, the formation of the patterned photoresist layer is incorporated with the oblique vapor-deposition to form the alignment units. Then, the alignment units are selectively formed on the substrate. In addition, the alignment layers are aligned simultaneously while the alignment layers are obliquely vapor-deposited, thereby simplifying the manufacturing steps. Furthermore, in the manufacturing method of the display device of the present embodiment, the alignment units on the active device array substrate and the opposite substrate are manufactured by using the photoresist remover. Afterwards, the sealant is disposed on the active device array substrate and the opposite substrate and surrounds the liquid crystal layer and the alignment units for assembling the opposite substrate with the active device array substrate. As a consequence, not only is the conventional problem of moisture invading into the liquid crystal layer via the alignment layer prevented, but the manufacturing yield rate is also enhanced. Hence, the display device of the embodiment in the present invention has superior display quality. 
     Although the present invention has been described with reference to the above embodiments, it will be apparent to one of the ordinary skill in the art that modifications to the described embodiment may be made without departing from the spirit of the invention. Accordingly, the scope of the invention will be defined by the attached claims not by the above detailed descriptions.