KR20020094638A - A method for manufacturing a thin film transistor substrate for a liquid crystal display of reflection type - Google Patents

Abstract

PURPOSE: A TFT substrate fabricating method for a reflective liquid crystal display device is provided to simplify the fabricating procedure by forming a single organic film between data lines and thin film transistors, and reflecting electrodes. CONSTITUTION: A method for fabricating a thin film transistor substrate for a reflective liquid crystal display device includes the steps of forming gate lines(22) on a substrate(10), forming a gate insulating film(30) covering the gate lines, forming a semiconductor pattern(42) on the gate insulating film, forming data lines intersecting the gate lines on the gate insulating film, source electrodes(65) connected to the data lines and the semiconductor pattern, and drain electrodes(66) connected to the semiconductor pattern in correspondence to the source electrodes, plasma-processing the surface of the semiconductor pattern, forming an organic film covering the semiconductor pattern, the data lines, the source electrodes and drain electrodes, selectively exposing and developing the organic film for forming an organic film pattern(71) with contact holes for exposing the drain electrodes and a concave and convex type top part, and forming reflecting electrodes(82) on the organic film pattern to be connected to the drain electrodes via the contact holes.

Description

A method for manufacturing a thin film transistor substrate for a liquid crystal display of reflection type}

The present invention relates to a method for manufacturing a thin film transistor substrate for a reflective liquid crystal display device.

The liquid crystal display is manufactured by injecting a liquid crystal material between an upper substrate on which a common electrode, a color filter, and the like are formed, and a lower substrate on which a thin film transistor, a pixel electrode, and the like are formed. In the liquid crystal display, an electric potential is applied to the pixel electrode and the common electrode to form an electric field, thereby changing the arrangement of liquid crystal molecules and thereby controlling the light transmittance to represent an image.

In the lower substrate, a plurality of pixel regions defined by crossing a plurality of gate lines and a plurality of data lines are arranged in a matrix, and each of the pixel regions includes a thin film transistor and a drain electrode of the thin film transistor electrically connected to the gate line and the data line. A pixel electrode to be connected is formed.

In the reflective liquid crystal display device, instead of the pixel electrode, a reflective electrode having light reflection characteristics is formed, and the reflective electrode has a concave-convex shape in order to increase the reflectance.

The manufacturing process of the reflective liquid crystal display device is briefly described as follows.

A gate wiring including a gate line and a gate electrode is formed on the substrate, and the gate wiring is covered with a gate insulating film. Next, a semiconductor pattern is formed on the gate insulating film, and a data line including a data line, a source electrode, and a drain electrode is formed. Subsequently, after forming a protective film made of silicon nitride covering the gate wiring and the semiconductor pattern, the protective film is etched to form a contact hole that exposes the drain electrode. Subsequently, after the entire surface of the organic film is applied, two exposure and development operations are performed to expose the contact hole exposing the drain electrode, and the surface is patterned to have an uneven shape. Next, a reflective electrode connected to the drain electrode is formed on the organic layer. At this time, the reflective electrode has a concave-convex surface according to the concave-convex shape of the surface of the organic insulating film.

However, when manufacturing a liquid crystal display device through such a manufacturing method, the process becomes complicated because a process of depositing a protective film, performing a photolithography process, and applying and photolithography an organic layer must be performed before forming a reflective electrode. There is. However, when only the organic layer is applied to such a reflective liquid crystal display, a problem arises in that switching characteristics of the thin film transistor are poor, such as high gate-off current.

An object of the present invention is to provide a method of manufacturing a thin film transistor substrate for a reflective liquid crystal display device which can improve the characteristics of the thin film transistor and at the same time simplify the manufacturing process.

1 is a layout view of a thin film transistor substrate for a reflective liquid crystal display device according to an exemplary embodiment of the present invention.

FIG. 2 is a view showing the substrate shown in FIG. 1 along a cutting line II-II '; FIG.

3A is a layout view of a substrate in a first manufacturing step in manufacturing a thin film transistor substrate for a reflective liquid crystal display according to an exemplary embodiment of the present invention.

3B is a cross-sectional view of the substrate along the cutting line IIIb-IIIb 'shown in FIG. 3A,

4A is a layout view of a substrate in the next manufacturing step of FIG. 3A,

4B is a cross-sectional view of the substrate along the cutting line IVb-IVb ′ shown in FIG. 4A.

FIG. 5A is a layout view of a substrate in a subsequent manufacturing step of FIG. 4A,

5B is a cross-sectional view of the substrate along the cutting line Vb-Vb ′ shown in FIG. 5A.

FIG. 6A is a layout view of a substrate in a subsequent manufacturing step of FIG. 5A;

6B is a cross-sectional view of the substrate along the cutting line VIb-VIb ′ shown in FIG. 6A.

7 and 8 illustrate the electrical characteristics of the first type reflective liquid crystal display manufactured according to the embodiment of the present invention.

9 and 10 illustrate electrical property results of a second type reflective liquid crystal display manufactured according to an exemplary embodiment of the present invention.

In order to solve this technical problem, in the present invention, only the organic film is formed as a protective film covering the thin film transistor, but before the organic film is formed, the substrate is subjected to plasma treatment.

Specifically, the method of manufacturing a thin film transistor substrate for a reflective liquid crystal display device according to the present invention includes the steps of forming a gate line on the substrate; Forming a gate insulating film covering the gate line; Forming a semiconductor pattern on the gate insulating film; Forming a data line crossing the gate line, a source electrode connected to the data line and connected to the semiconductor pattern, and a drain electrode connected to the semiconductor pattern corresponding to the source electrode on the gate insulating layer; Plasma treating the surface of the semiconductor pattern; Forming an organic layer covering the semiconductor pattern and the data line, the source electrode and the drain electrode; Selectively exposing and developing the organic film to form an organic film pattern having a contact hole exposing the drain electrode and having an upper portion patterned into an uneven shape; Forming a reflective electrode connected to the drain electrode through the contact hole on the organic layer pattern.

Here, in the plasma treatment, an inert gas may be used in a plasma state or oxygen may be used in a plasma state. In addition, the silicon nitride can be used in a plasma state, in which case it is preferable to proceed the plasma treatment for 2 seconds to 5 seconds.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

The following experiment is to explain the results of testing the electrical characteristics of the liquid crystal display manufactured by the present invention.

FIG. 1 is a layout view of a thin film transistor substrate for a reflective liquid crystal display device according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the substrate shown in FIG. 1 along a cutting line II-II '.

The gate line 22 and the gate line 22 which are formed at one end of the gate line 22 and the gate line 22 extending in the horizontal direction on the insulating substrate 10 to transfer the scanning signal to the gate line 22. Gate wirings 22, 24, and 26 are formed including the gate electrode 26 protruding from the top.

The gate wirings 22, 24, and 26 are advantageously formed of a low resistance metal material in order to be applied to a large area liquid crystal display device. In addition, the gate wirings 22, 24, and 26 may be formed in a single layer structure, or may be formed in a double layer structure or more. In the case of the single layer structure, the chromium or chromium alloy, molybdenum or molybdenum alloy, aluminum or aluminum alloy may be formed. Silver or a silver alloy is used, and when formed in a double layer structure, at least one of the two layers is preferably formed of a low resistance metal material.

On the insulating substrate 10, a gate insulating film 30 made of silicon nitride or the like covers the gate wirings 22, 24, 26, 27, and 29.

A semiconductor pattern 42 made of a semiconductor such as amorphous silicon is formed on the gate insulating layer 30, and an amorphous silicon or the like doped with a high concentration of impurities is formed on the semiconductor pattern 42. Resistive contact patterns 55 and 56 are formed, respectively.

On the gate insulating layer 30, the data line 62 and the data line 62 defining the pixel area are intersected with the gate line 22 extending in the horizontal direction, and the image signal is transmitted to the data line 62. The resistive contact layer 56 corresponding to the source electrode 65 and the source electrode 65 extending from the data pad 64, the data line 62, and in contact with the resistive contact layer 55. Data wirings 62, 64, 65, and 66 are formed including the drain electrodes 66 in contact with each other.

The data lines 62, 64, 65, and 66 are advantageously formed of a low resistance metal material in order to be applied to a large area liquid crystal display. In addition, the data lines 62, 64, 65, and 66 may also be formed in a single layer structure or in a double layer structure or the same as the gate lines 22, 24, and 26. Chromium or chromium alloys, molybdenum or molybdenum alloys, aluminum or aluminum alloys, or silver or silver alloys are used, and when formed in a double layer structure, at least one of the two layers is preferably formed of a low resistance metal material.

Here, the gate electrode 26, the semiconductor pattern 42, the source electrode 65, and the drain electrode 66 constitute a thin film transistor TFT.

An organic layer pattern 71 is formed on the data lines 62, 64, 65, and 66 and the thin film transistor TFT, and the upper portion is patterned in an uneven shape.

In the organic layer pattern 71, first and second contact holes 72 and 74 exposing the drain electrode 66 and the data pad 64, respectively, are formed, and the gate pad 30 is formed together with the gate insulating layer 30. A third contact hole 76 is formed which exposes 24. In this case, the organic layer pattern 71 may be formed such that the organic layer does not exist around the gate pad 24 and the data pad 64.

On the organic layer pattern 71, a reflective electrode 82 electrically connected to the drain electrode 66 through the first contact hole 72 is formed in the pixel area. The reflective electrode 82 has a concave-convex shape on its surface in accordance with the concave-convex shape of the organic film pattern 71. The reflective electrode 82 may be formed of a metal material having excellent reflective properties, for example, aluminum or aluminum alloy, or silver or silver alloy.

In addition, on the organic layer pattern 71, an auxiliary data pad 84 connected to the data pad 64 through a second contact hole 74 and a third contact hole 76 are connected to the gate pad 24. An auxiliary gate pad 86 is formed.

Next, a method of manufacturing the liquid crystal display according to the exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3A to 7B and FIGS. 1 and 2.

First, as shown in FIGS. 3A and 3B, a metal layer made of aluminum or an aluminum alloy, chromium or chromium alloy, molybdenum or molybdenum alloy, titanium or titanium alloy, or tantalum or tantalum alloy is deposited on the insulating substrate 10. The metal layer is patterned by a photolithography process to form a plurality of gate wirings including the gate lines 22, the gate pads 24, and the gate electrodes 26.

Next, as illustrated in FIGS. 4A and 4B, after sequentially stacking three layers of the gate insulating film 30, the semiconductor layer, and the semiconductor layer doped with impurities, the semiconductor layer and the semiconductor layer doped with impurities are subjected to a photolithography process. Patterning is performed to form the ohmic contact layer pattern 52 and the semiconductor pattern 42 corresponding to the gate electrode 26.

Next, as shown in FIGS. 5A and 5B, a metal layer made of chromium or chromium alloy, molybdenum or molybdenum alloy, titanium or titanium alloy, tantalum or tantalum alloy is deposited on the gate insulating layer 30 and the semiconductor pattern 42. Subsequently, the metal layer is patterned by a photolithography process to form a data line including a data line 62, a data pad 64, a source electrode 65, and a drain electrode 66.

Subsequently, the ohmic contact layer pattern 52 is etched using the data wiring as a mask to separate the ohmic contact layer 55 contacting the source electrode 65 and the ohmic contact layer 56 contacting the drain electrode 65. .

6A and 6B, the surface of the substrate on which the data line and the thin film transistor are formed is treated with plasma. At this time, an inert gas such as He, H2, Ar, or O2 or SiNx is made into a plasma state, and the portion of the semiconductor pattern 42 exposed between the two ohmic contact layers 55 and 56 is processed using this plasma. . Such surface treatment of the semiconductor pattern by plasma can stabilize the characteristics of the thin film transistor. At this time, the plasma treatment using SiNx is preferably performed in a short time of 2 seconds to 5 seconds so that the silicon nitride film is not formed on the substrate.

Subsequently, an organic film made of an acrylic organic material such as PC-455, bisbenzocyclobutene (BCB), or perfluorocyclobutene (PFCB) is coated on the plasma-treated substrate, and then the organic film is patterned by a photolithography process to expose the drain electrode 66. The first contact hole 72, the second contact hole 74 exposing the data pad 64, and the hole exposing the portion of the gate insulating film 30 on the gate pad 24 are formed, and the organic pattern is patterned in an uneven shape on the top thereof. The film pattern 71 is formed. Subsequently, a portion of the gate insulating layer 30 on the gate pad 24 is etched using the organic layer pattern 71 as a mask, and the third contact hole 76 exposing the gate pad 24 is an organic passivation layer pattern 71. And a gate insulating film 300.

In order to form the organic film pattern 71 as described above, two exposure processes are successively performed on the applied organic film. The first contact hole 72, the gate pad 24, and the data are performed through the first exposure process. Selective exposure to define a second light third contact hole 74, 76 exposing the pad 64, and a conventional embossing exposure that allows the top of the organic film to be patterned into an uneven shape through the second exposure process. Proceed throughout the act. Thereafter, as described above, when the organic film having undergone two exposure processes is developed, the organic film pattern 71 as shown in the drawing can be formed.

Here, instead of forming the second and third contact holes 74, 76 exposing the data pad 64 and the gate pad 24, the data pad 64 portion and the gate pad 24 in the first exposure process. The entire peripheral portion may be exposed, and the organic layer of the pads 24 and 64 may be removed through a subsequent process to expose both the data pad 64 and the gate pad 24.

Next, again, as shown in FIGS. 1 and 2, an aluminum or aluminum alloy is formed on the resulting substrate on which the organic film pattern 71 and the first, second and third contact holes 72, 74, and 76 are formed. After depositing a metal material layer having excellent reflective properties such as silver or silver alloy, the reflective electrode 82 and the second contacting the drain electrode 66 through the first contact hole 72 are patterned by a photolithography process. The auxiliary data pad 84 that contacts the data pad through the contact hole 74 and the auxiliary gate pad 86 that contacts the gate pad 24 through the third contact hole 76 are formed.

The method for manufacturing a thin film transistor substrate for a reflective liquid crystal display device according to the present invention as described above forms only one organic film between the data line and the thin film transistor and the reflective electrode, thereby reducing the number of masks used and film deposition. And the photolithography process can be reduced to simplify the manufacturing process.

7 and 8 are manufactured according to an embodiment of the present invention, the organic film pattern is formed to a thickness of 3.6㎛ using PC-455, the gate insulating film is formed of a thickness of 4500Å using silicon nitride The electrical characteristics of the Type 1 reflective liquid crystal display device were tested. 7 illustrates an off current Ioff value, an on current Ion value, and a threshold voltage Vth value, and FIG. 8 illustrates an on / off current characteristic curve.

As shown in FIG. 7 and FIG. 8, the electrical characteristics of the first type reflective liquid crystal display manufactured according to the embodiment of the present invention are good. In particular, in the off current value, the off current in a typical reflective liquid crystal display device manufactured by forming an inorganic protective film and an organic film pattern between the data wiring and the thin film transistor and the reflective electrode is about 10 ^-12 to 10 ^-13 . In consideration of, the off-current value shown by the reflective liquid crystal display device manufactured according to the exemplary embodiment of the present invention is lower, so that the device characteristics are excellent.

9 and 10 are made in accordance with the present invention, the organic film pattern is formed to a thickness of 1.8㎛ using BCB, the second type reflective liquid crystal formed a gate insulating film to a thickness of 4500Å using silicon nitride The test results of the electrical characteristics of the display device are shown. 9 illustrates an off current Ioff value, an on current Ion value, and a threshold voltage Vth value, and FIG. 10 illustrates an on / off current characteristic curve.

9 and 10, the electrical characteristics of the second type reflective liquid crystal display manufactured according to the exemplary embodiment of the present invention may also be satisfactory.

Through these test results, it can be seen that a liquid crystal display device having excellent device characteristics can be manufactured even after forming a single organic film after plasma treatment according to the present invention.

In the present invention, since only a single organic film is formed between the data line and the thin film transistor and the reflective electrode to manufacture the thin film transistor substrate for the reflective liquid crystal display device, the manufacturing process can be simplified.

Claims (4)

Forming a gate line on the substrate, Forming a gate insulating film covering the gate line; Forming a semiconductor pattern on the gate insulating layer; Forming a data line crossing the gate line, a source electrode connected to the data line and connected to the semiconductor pattern, and a drain electrode connected to the semiconductor pattern in correspondence to the source electrode, on the gate insulating layer; Plasma processing the surface of the semiconductor pattern; Forming an organic layer covering the semiconductor pattern and the data line, the source electrode, and the drain electrode; Selectively exposing and developing the organic layer to form an organic layer pattern having contact holes exposing the drain electrode and having an upper portion patterned into an uneven shape, Forming a reflective electrode connected to the drain electrode through the contact hole on the organic layer pattern Method of manufacturing a thin film transistor substrate for a reflective liquid crystal display device comprising a. In claim 1, A method of manufacturing a thin film transistor substrate for a reflective liquid crystal display device using plasma of an inert gas for the plasma treatment. In claim 1, A method of manufacturing a thin film transistor substrate for a reflective liquid crystal display device, wherein the plasma process uses oxygen in a plasma state. In claim 1, A method for manufacturing a thin film transistor substrate for a reflective liquid crystal display device using silicon nitride in a plasma state for the plasma treatment.