KR20020056705A - Method for manufacturing the thin film transistor liquid crystal display device - Google Patents

Abstract

PURPOSE: A method of fabricating a thin film transistor liquid crystal display is provided to reduce the number of mask processes so as to decrease TFT-LCD manufacturing cost. CONSTITUTION: A metal film is deposited on a transparent insulating substrate(11) and patterned through the first mask process, to form a gate electrode(13). An active layer(15) and a metal layer(17) used for forming source and drain electrodes are sequentially formed on the transparent insulating substrate and patterned through the second mask process, to form the source and drain electrodes(17a,17b), simultaneously. The active layer is selectively removed using the source and drain electrodes as a mask. A passivation layer having an alignment function is formed on the overall surface of the substrate.

Description

Method for manufacturing the thin film transistor liquid crystal display device

The present invention relates to a thin film transistor liquid crystal display device, and more particularly, to a method of manufacturing a thin film transistor liquid crystal display device using a two-mask process using graytone.

In general, in a liquid crystal display device, an active matrix liquid crystal display device has a high speed response and has a large number of pixels. As a result, the display screen has high quality, large size, color screen, and the like, and is used in portable televisions, notebook computers, personal computers, automobile navigation systems, and the like.

In such an active matrix type liquid crystal display device, a switching element such as a diode or a thin film transistor is disposed at a portion where a gate line and a data line cross each other to selectively turn on / off a pixel electrode.

In the conventional method of manufacturing a liquid crystal display including the thin film transistor, a metal layer for a gate electrode and a storage electrode is deposited to a predetermined thickness on an insulating substrate, although not shown in the drawing, and then the metal film is formed through a first mask process. A predetermined portion is patterned to form a gate electrode and a storage electrode.

Subsequently, although not shown in the drawing, a gate insulating film is deposited on the insulating substrate on which the gate electrode and the storage electrode are formed to a predetermined thickness, and then an amorphous silicon layer and a doped semiconductor layer, which serve as a channel of the thin film transistor, are sequentially deposited. . Thereafter, the amorphous silicon layer and the doped semiconductor layer are patterned to exist in the planar region of the thin film transistor by a second mask process.

Next, although not shown in the drawings, a source and drain metal film is deposited on the resultant insulating substrate, and then the source and drain electrodes are formed through a third mask process so that the metal film is present on both sides of the amorphous silicon layer.

Subsequently, although not shown in the drawing, after forming a passivation layer on the insulating substrate on which the source and drain electrodes are formed, the passivation layer is etched through a fourth mask process so that a predetermined portion of the source electrode is exposed to form a via hole. Form.

Subsequently, although not shown in the drawing, an ITO (Indium Tin Oxide) film is deposited on the passivation layer so as to contact the source electrode exposed through the via hole, and the pixel electrode is formed by etching a predetermined portion of the ITO film through a fifth mask process. do.

However, as described above, at least five mask processes are required to form the lower substrate of the conventional thin film transistor liquid crystal display.

In this case, the etching process is a photolithography process, as is known, and includes a resist coating process, an exposure process, a developing process, an etching process, and a resist removing process only by its own process. As a result, it takes a long time to perform one mask process.

For this reason, a very long time is required to manufacture a thin film transistor liquid crystal display including at least five mask processes, and there are problems such as an increase in manufacturing cost and a decrease in yield.

Accordingly, the present invention has been made to solve the problems of the prior art, an object of the present invention is to provide a method for manufacturing a thin film transistor liquid crystal display device that can reduce the manufacturing cost by reducing the mask process.

1 to 5 are cross-sectional views for each process for explaining a method of manufacturing a thin film transistor liquid crystal display device according to the present invention.

<Description of the symbols for the main parts of the drawings>

11: glass substrate 13: gate electrode

15: active layer 17: metal layer for source and drain electrodes

17a: drain electrode 17b: source electrode

19: shield

A method of manufacturing a thin film transistor liquid crystal display device according to the present invention for achieving the object of the present invention, by depositing a metal film on a transparent insulating substrate, and selectively patterning the metal film in a first mask process to form a gate electrode step; The metal layer for the active layer, the data, and the pixel electrode is sequentially formed on the entire surface of the transparent insulating substrate on which the gate electrode is formed, and the metal layer for the active layer, the data, and the pixel electrode is patterned by a second mask process. Simultaneously forming; Selectively removing the active layer using the data electrode as a mask; And forming a protective film having an alignment film function on the entire surface of the thin film transistor.

Hereinafter, a thin film transistor liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings.

1 to 5 are cross-sectional views of respective processes for explaining the thin film transistor liquid crystal display according to the present invention.

In the thin film transistor liquid crystal display device according to the present invention, as shown in FIG. 1, a transparent insulating substrate, for example, a glass substrate 11 is prepared first, and then a gate metal layer (not illustrated) is formed using a highly conductive metal. Is deposited to a predetermined thickness by sputtering or the like. Then, the formed gate metal layer is subjected to a series of mask processes using a mask of a desired shape (not shown) and the first mask in the present invention to form a gate electrode 13. (First mask process)

Next, as shown in FIG. 2, a gate insulating film, an amorphous silicon layer used as a semiconductor layer, and a doped amorphous silicon layer used as an ohmic layer are formed on the entire surface of the glass substrate 11 on which the gate electrode 13 is formed. The active layer 15 constituted is deposited, and the soot and drain metal layers 17 are successively deposited on the active layer 15.

In this case, in the source and drain electrode metal layers 17, different application examples of the present invention may be applied to ITO or low resistance transparent electrodes applied to a small transmissive liquid crystal display device, and to a large reflective liquid crystal display device. It can be divided into reflective metals such as aluminum.

Here, in the case of the former, that is, when ITO is used as the metal layer 17 for the source and drain (data bus line) electrodes, the data signal may be distorted due to the resistance of the data line depending on the size of the display. It is practically possible if the display is less than 5 inches.

In addition, considering the electrical characteristics of the thin film transistor and a display larger than the display of 4 to 5 inches or less, ITO deposition is performed by forming a doped amorphous silicon layer used as the ohmic layer as a microcrystal or a silicon compound. In this way, if the resistance to some extent is achieved, ITO can be applied to the metal layer for the source and drain (data busline) electrodes. Here, examples of the silicon compound include molybdenum silicon (MoSi), tantalum silicon (TaSi), chromium silicon (CrSi) or tungsten silicon (WSi) compounds.

Alternatively, as in the latter example, in the case of the reflective liquid crystal display device, the source and drain electrodes 17 are formed using aluminum or silicon instead of ITO transparent electrodes by several% or other reflective metals. In this case, since the wiring resistance is not limited, the other reflective metal can be used as the data electrode even in a medium size or larger display.

Next, as shown in FIG. 3, a second mask process is performed on the active layer 15, the source and drain electrode metal layers 17. Here, in order to simultaneously form the source 17a, the drain electrode 17b, and the pixel electrode (not shown), a gray tone mask is used as the second mask during pattern exposure. (Second mask process)

That is, after partial exposure and development are performed on the source and drain metal layer 17 using a gray mask, a portion of the source and drain metal layer 17 including a region defined as the thin film transistor channel portion is etched. In this case, the source and drain regions exposed by the gray tone mask may have sufficient coverage during the etching process of the active layer 15, which will be described later, by remaining the photoresist by an appropriate amount.

Next, as shown in FIG. 4, the source and drain electrodes 17a and 17b are formed by ashing to remove the photoresist remaining on the partially etched source and drain electrode metal layers 17. The channel 17a and the drain electrode 17b are etched again, and the ohmic layer in the active layer 15 is removed to complete the channel portion of the thin film transistor.

At this time, during the etching process of the active layer 15, the active layer 15 is etched up to the active layer to open an insulating layer of a gate pad portion (not shown). In this case, since the source and drain electrode metal layers 17 are used as masks, a separate mask is not required.

Subsequently, the passivation layer 19 is formed on the entire surface of the glass substrate 11 including the formed source 17a and the drain electrode 17b. At this time, by using an organic overcoat agent or an alignment film such as polyimide or polyamic acid as the material of the protective film 19, process steps required for forming the alignment film are reduced.

When the gray tone mask as described above is used, the lower array substrate of the thin film transistor liquid crystal display device can be manufactured by two mask processes.

The above embodiments are not intended to limit the present invention thereto, but rather represent one embodiment of the present invention. In addition, it can implement in various changes within the range which does not deviate from the summary of this invention.

As described above, the thin film transistor liquid crystal display according to the present invention has the following effects.

Conventional thin film transistor manufacturing technology is mainly 5 mask process regardless of the back channel etch (BCE) structure / etch stopper (ES) structure, but the present invention reduced it to 2 mask process, which is a thin film transistor liquid crystal display In device manufacturing, the reduction of the mask process can considerably lower the manufacturing cost in consideration of equipment investment, development cost, processing time, manufacturing yield, productivity, and the like.

Claims (3)

Depositing a metal film on the transparent insulating substrate, and selectively patterning the metal film by a first mask process to form a gate electrode; The metal layer for the active layer, the data, and the pixel electrode is sequentially formed on the entire surface of the transparent insulating substrate on which the gate electrode is formed, and the metal layer for the active layer, the data, and the pixel electrode is patterned by a second mask process. Simultaneously forming; Selectively removing the active layer using the data electrode as a mask; And And forming a protective film having an alignment layer function on the entire surface of the thin film transistor. The method of claim 1, And the metal layer for the data and the pixel electrode is made of ITO or a reflective metal. The method of claim 2, And forming a gate insulating film in the active layer when the data electrode and the pixel electrode are formed at the same time.