| Manufacturing process of thin film transistor liquid crystal display -> Monitor Keywords |
|
|
  Manufacturing process of thin film transistor liquid crystal displayUSPTO Application #: 20060038181Title: Manufacturing process of thin film transistor liquid crystal display Abstract: A process for manufacturing a thin film transistor liquid crystal display (TFT-LCD) is disclosed. The process can reduce the number of the mask used in the photolithography process to three masks, form a capacitor during the manufacturing process simultaneously, and enhance the transmission rate of the TFT-LCD. Because the pixel electrodes are formed directly on the substrate, without forming an insulator layer in the pixel area, the transmission can be enhanced. The manufacturing process also provides a protective circuit for avoiding electrostatic discharge damage, and a passivation layer to protect the capacitor, the gate line, and the signal line. (end of abstract) Agent: Richard P. Berg C/o Ladas & Parry - Los Angeles, CA, US Inventor: Shiuh-Ping Tseng USPTO Applicaton #: 20060038181 - Class: 257072000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Non-single Crystal, Or Recrystallized, Semiconductor Material Forms Part Of Active Junction (including Field-induced Active Junction), Field Effect Device In Non-single Crystal, Or Recrystallized, Semiconductor Material, In Array Having Structure For Use As Imager Or Display, Or With Transparent Electrode The Patent Description & Claims data below is from USPTO Patent Application 20060038181. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This patent application is a continuation application of U.S. Ser. No. 10/338,421, filed on Jan. 7, 2003, which is a divisional application of U.S. Ser. No. 09/976,771, filed on Oct. 12, 2001, which claims priority to Taiwanese Application No. 89121295, filed on Oct. 12, 2000. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates in general to a manufacturing process of a thin film transistor liquid crystal display (TFT-LCD). In particular, the present invention relates to a TFT-LCD manufacturing process using three photolithography process masks. [0004] 2. Description of the Related Art [0005] A liquid crystal display (LCD) employing a thin film transistor (TFT) as an active device provides advantages of low power consumption, thin profile, light weight and low driving voltage. However, the TFT process consists of multiple masks in multiple photolithography processes, usually more than seven masks, thereby encountering the problems of poor yield and high cost. In order to improve the problems, reducing the steps of the photolithography process becomes an important issue. [0006] U.S. Pat. No. 5,478,766 discloses a process for forming of a TFT-LCD by multiple photolithography processes using three masks. FIGS. 1A to 1C show top views of the masks used in the TFT-LCD manufacturing process according to the prior art, and FIGS. 2A to 2E are cross-sectional views along the line A-A' in FIGS. 1A to 1C of the prior art. First, as shown in FIG. 1A and FIG. 2A, a first metal layer is deposited on a substrate 21, and patterned by a first photolithography process to form a gate electrode 22 and a gate line (not shown) connected to the gate electrode 22. Usually, the metal layer is further oxidized to form a protecting layer 23 covering the gate electrode 22. Then, as shown in FIG. 2B, an insulating layer 24, an amorphous silicon layer 25 and a doped silicon layer 26 are deposited on the substrate 21. Next, as shown in FIGS. 1B and 2C, a second metal layer is deposited on the doped silicon layer 26. The second metal layer is then patterned as a signal line 27 and a source/drain metal layer 28 by a second photolithography process. AS shown in FIGS. 1C and 2D, an indium tin oxide (ITO) layer is deposited on the substrate 21. A photo resist layer (not shown) is then formed above the ITO layer, then the ITO layer is patterned to form a pixel electrode 29 by a third photolithography process. Finally, as shown in FIG. 2E, the same photo resist layer is used to define the patterns of the source/drain metal layer 28 and the doped silicon layer 26. A source electrode 31 and a drain electrode 32 are finally formed. [0007] According to the above process, the masks used in the photolithography process are reduced to three masks; however, an insulating layer 24 is formed between the pixel electrode 29 and the substrate 21, and the transmission of the display is decreased. Further, the first metal layer and the second metal layer cannot electrically connect for avoiding the damage of electrostatic discharge (ESD) because the insulating layer 24 is remained on the substrate 21. The reliability of the LCD may be poor because of the damage of electrostatic discharge (ESD) SUMMARY OF THE INVENTION [0008] An object of the present invention is to provide a process for manufacturing a thin film transistor liquid crystal display (TFT-LCD) by three masks, providing a protective circuit to avoid ESD effect, increasing the transmission of the TFT-LCD, and forming a capacitor in the TFT-LCD to solve the above problems. [0009] Another object of the present invention is to provide a process for manufacturing a thin film transistor liquid crystal display (TFT-LCD) with a protective structure to avoid capacitor shorts and shorts between the gate line and the signal line. [0010] In achieving the above objects, the process for manufacturing the thin film transistor liquid crystal display comprises the steps of: [0011] (a) providing a substrate having a transistor area, a capacitor area, a pixel area, and a gate pad area; [0012] (b) depositing and patterning a first metal layer on the substrate to form a gate electrode, a capacitor upper electrode, and a pad electrode respectively in the transistor area, the capacitor area, and the gate pad area; [0013] (c) depositing and patterning an insulating layer, a semiconductor layer, a doped silicon layer and a second metal layer to (1) form an TFT island structure in the transistor area and a capacitor in the capacitor area, and (2) remove the second metal layer, the doped silicon layer, the semiconductor layer and the insulating layer in the pixel area and the gate pad area to expose the substrate in the pixel area and expose the pad electrode in the gate pad area; and [0014] (d) depositing a transparent conducting layer, and (1) patterning the transparent conducting layer by defining a channel area in the transistor area, and removing the transparent conducting layer within the channel area, and (2) removing parts of the second metal layer and the doped silicon layer uncovered by the transparent conducting layer so as to define a source electrode and a drain electrode in the transistor area, therefore, the source electrode and the drain electrode being separated by the channel area to expose the semiconductor layer in the channel area. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The present invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein: [0016] FIGS. 1A to 1C are top views showing the steps of the TFT-LCD manufacturing process according to the prior art. [0017] FIGS. 2A to 2E are cross-sectional views along the line A-A' in FIG. 1A to FIG. 1C according to the prior art. [0018] FIGS. 3A to 3C are top views of the first embodiment of a TFT-LCD according to the present invention. [0019] FIGS. 4A to 4D are cross-sectional views of FIG. 3A to FIG. 3C along the lines B-B' and C-C'. [0020] FIGS. 5A to 5C are cross-sectional views showing the structure of the electrostatic discharge (ESD) protective circuit. Continue reading... Full patent description for Manufacturing process of thin film transistor liquid crystal display Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Manufacturing process of thin film transistor liquid crystal display patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Manufacturing process of thin film transistor liquid crystal display or other areas of interest. ### Previous Patent Application: Method and apparatus for solution processed doping of carbon nanotube Next Patent Application: Pixel structure Industry Class: Active solid-state devices (e.g., transistors, solid-state diodes) ### FreshPatents.com Support Thank you for viewing the Manufacturing process of thin film transistor liquid crystal display patent info. IP-related news and info Results in 1.48479 seconds Other interesting Feshpatents.com categories: Software: Finance , AI , Databases , Development , Document , Navigation , Error |
||
