KR20040078369A - Thin film transistor substrate - Google Patents

Abstract

PURPOSE: A TFT substrate is provided to improve the reflectance and the display quality by forming a contact hole on an interface between a reflecting window and a transmitting window. CONSTITUTION: An active pattern(202) is formed on an insulating substrate. A gate insulating layer(204) is formed on the insulating substrate and the active pattern. A gate electrode(205) is formed on the gate insulating layer. An interlayer dielectric(208) is formed on the gate electrode and the gate insulating layer. A source/drain electrode(206,207) is formed on both sides of an overlapped region between the active pattern and the gate insulating layer by patterning the interlayer dielectric. A protective layer having a contact hole is formed on the source/drain electrode and the interlayer dielectric. A reflective electrode(290) is formed on the protective layer.

Description

Thin Film Transistor Boards {THIN FILM TRANSISTOR SUBSTRATE}

The present invention relates to a thin film transistor substrate, and more particularly, to a thin film transistor substrate for improving display quality.

The liquid crystal display device is classified into a reflective liquid crystal display device that receives an external first light and displays an image and a transmissive liquid crystal display device that receives an internally generated second light and displays an image. Recently, in order to realize high quality images while reducing power consumption, a reflection-transmissive liquid crystal display device utilizing both the advantages of the reflective liquid crystal display and the transmissive liquid crystal display has been developed.

Such a reflection-transmissive liquid crystal display displays an image in a reflection mode using the first light in a place where the external light amount is abundant, and uses a second light generated by consuming electric energy charged in itself when the external light amount is insufficient. The image is displayed in the transmission mode used.

In the reflection-transmissive liquid crystal display device, a reflection window and a transmission window exist simultaneously in a pixel, and thus require high characteristics of both reflectance and transmittance. Therefore, the reflectance and the transmittance are closely related to the area of the reflecting window and the transmitting window.

That is, the reflectance and transmittance tend to increase in proportion to the area. However, in general, as the reflection area increases, the transmission area decreases, and thus there is an inverse relationship between the reflectance and the transmittance.

In the case of a reflection-transmissive liquid crystal display, an organic film is used to form a reflection window. Since the organic film functions as an interlayer insulating film, an electrical connection between a source / drain metal region and indium tin oxide used as a common electrode is used. Form a contact hole for this purpose.

Such contact holes are generally formed in the reflecting plate area but do not contribute to the reflectance at all.

1 is a graph showing the relationship between the area of a contact hole and reflectance.

The S graph shows a case where the area of the contact hole is 5 μm × 5 μm, and the L graph shows a reflectance when the area of the contact hole is 11 μm × 10 μm. Each graph shows the results of several experiments.

If the area of the contact hole is 5 μm × 5 μm, the reflectance is between 7% and 9%, whereas if the area of the contact hole is 11 μm × 10 μm, the reflectance is between 5% and 7%. .

Therefore, it can be seen that the reflectance decreases as the area of the contact hole increases.

Therefore, the contact hole size should be reduced to improve the reflectance, but there is a need for a method of preventing the reflectance from being reduced while maintaining the contact hole size because a contact problem of the common electrode may occur.

That is, although the contact hole is an essential part for connecting the source / drain metal region and the common electrode, the contact hole is formed in the reflecting plate region, thereby reducing the reflectance.

Accordingly, an object of the present invention is to provide a thin film transistor substrate for improving the light reflection efficiency of the reflective electrode without affecting the light transmittance.

1 is a graph showing the relationship between the area of a contact hole and reflectance.

2 is a cross-sectional view illustrating a poly-si type thin film transistor substrate according to an exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating a poly-si type thin film transistor substrate according to another exemplary embodiment of the present invention.

4 illustrates a-si type thin film transistor substrate according to an exemplary embodiment of the present invention.

5 is a view showing a-si type thin film transistor substrate according to another feature of the present invention.

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

100: insulated substrate 120, 205: gate electrode

140, 204: gate insulating film 160, 202: active pattern

200a, 206: source electrode 200b, 207: drain electrode

220, 230: organic insulating film 270: contact hole

280: transparent electrode

In order to achieve the above object, a poly-si type thin film transistor according to an embodiment of the present invention includes an active pattern formed on an insulating substrate; A gate insulating film formed on the insulating substrate and the active pattern; A gate electrode formed on the gate insulating film; An interlayer insulating film formed on the gate electrode and the gate insulating film; Source / drain electrodes formed on both sides of the region where the active pattern and the gate insulating layer overlap by patterning the interlayer insulating layer; A protective film formed on the source / drain electrodes and the interlayer insulating film and having a contact hole partially exposing the source electrode and the interlayer insulating film; And a reflective electrode formed on the passivation layer in a predetermined pattern and having a plurality of transmission windows including a partial region of the contact hole.

In addition, an a-si type thin film transistor according to an embodiment of the present invention includes a gate electrode formed on an insulating substrate; A gate insulating film formed on the insulating substrate and the gate electrode; Source / drain electrodes formed on both sides of regions where the gate electrode and the gate insulating layer overlap with each other; A protective film formed on the source / drain electrode and the gate insulating film and having a contact hole partially exposing the source electrode and the gate insulating film; And a reflective electrode formed on the passivation layer in a predetermined pattern and having a plurality of transmission windows including a partial region of the contact hole.

In the present invention, the object can be achieved by forming contact holes to expose both the source electrode and the interlayer insulating film or gate insulating film.

That is, by forming a contact hole at the boundary between the reflection area and the transmission area, the reflectance is improved without affecting the light transmittance.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention.

2 is a cross-sectional view illustrating a poly-si type thin film transistor substrate according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a thin film transistor (TFT) substrate 1000 covers an insulating substrate 100 and a thin film transistor 200 provided on the insulating substrate 100 by a poly-si TFT process. And an organic switching layer 230, a transparent electrode 280 provided on the organic insulating layer 230, and a reflective electrode 290 provided on the transparent electrode 280.

Specifically, the insulating substrate 100 is processed into a silicon wafer to form polysilicon 202 using general semiconductor processing equipment, and then the polysilicon 202 is oxidized to form the gate insulating layer 204 and the gate insulating layer 204. ), The gate electrode 205 is formed by dry etching.

The interlayer insulating film 208 is deposited on the gate insulating film 204 on which the gate electrode 205 is formed, and the hole is formed at the position where the source / drain electrodes 206 and 207 are to be formed in the interlayer insulating film 208. Metals such as aluminum are deposited on the source and drain electrodes 206 and 207.

After forming the source / drain electrodes 206 and 207, an organic insulating layer 230 is deposited.

The contact hole 270 is formed on the surface of the organic insulating layer 230 to expose the source electrode 206 of the thin film transistor 200.

The transparent electrode 280 is made of indium tin oxide (ITO) or indium zinc oxide (IZO), and has a predetermined thickness on the organic insulating layer 230. Accordingly, the thin film transistor 200 is electrically connected to the source electrode 206 of the thin film transistor 200 through the contact hole 270 formed in the organic insulating layer 230.

The reflective electrode 290 is provided on the transparent electrode 290 having a shape of an isotropic polygon protruding from each other, and each of the reflective electrodes 290 is provided to be spaced apart from each other without being in contact with each other.

The reflective electrode 290 is made of a metal having excellent reflectance such as aluminum (Al). In addition, the reflective electrode 290 is provided to have the same height from the transparent electrode 280 and the profile of the reflective electrode 290 are all the same.

Since the reflective electrode 290 has independent island shapes on the transparent electrode 280, the thin film transistor substrate 1000 receives light incident from the outside from a region where the reflective electrode 290 is provided. By the light generating means (not shown) provided below the insulating substrate 100 to the reflective region R for reflecting and the transparent electrode 280 which is not provided with the reflective electrode 290 and is exposed to the outside. A transmission area T for transmitting the light emitted is provided.

Therefore, when light is incident from the outside, the light is reflected by the reflective electrode, and the light emitted from the light generating means passes through the transparent electrode.

Here, the contact hole 270 is formed over the interface between the reflective window (R) and the transmission window (T).

That is, the contact hole 270 is formed with the edge A of the region where the interlayer insulating film 208 and the source electrode 206 overlap and the side surface B of the source electrode extending from the edge A as a bottom surface. do.

By taking such a structure, the area of the contact hole 270 may be reduced to 1/2, thereby increasing the reflectance, and not affecting the transmittance without increasing the area of the reflecting window.

3 is a view illustrating a poly-si type thin film transistor substrate according to another feature of the present invention.

Referring to FIG. 3, a thin film transistor (TFT) substrate 2000 covers an insulating substrate 100 and a thin film transistor 200 provided on the insulating substrate 100 by a poly-si TFT process. And an organic switching layer 230, a transparent electrode 280 provided on the organic insulating layer 230, and a reflective electrode 290 provided on the transparent electrode 280.

The contact hole 270 is formed on the surface of the organic insulating layer 230 to expose the source electrode 206 of the thin film transistor 200.

The transparent electrode 280 is made of indium tin oxide (ITO) or indium zinc oxide (IZO), and has a predetermined thickness on the organic insulating layer 230. Accordingly, the thin film transistor 200 is electrically connected to the source electrode 206 of the thin film transistor 200 through the contact hole 270 formed in the organic insulating layer 230.

Here, the contact hole 270 is formed over the interface between the reflective window (R) and the transmission window (T).

The contact hole 270 may include an edge A of a region where the interlayer insulating layer 208 and the source electrode 206 overlap each other, a side surface B of the source electrode extending from the edge A, and a part of the interlayer insulating layer. It is formed with the area C as the bottom surface.

Even if a part C of the interlayer insulating layer is added to the bottom surface, the same result as that of the contact hole 270 shown in FIG. 2 is obtained.

Other structures except for the bottom of the contact hole 270 are the same as those described with reference to FIG. 2, and thus the rest of the description will be omitted.

By taking such a structure, the area of the contact hole 270 may be reduced to 1/2, thereby increasing the reflectance, and not affecting the transmittance without increasing the area of the reflecting window.

4 illustrates a-si type thin film transistor substrate according to an exemplary embodiment of the present invention.

Referring to FIG. 4, as a gate film on a transparent substrate 100 made of glass, quartz or sapphire, for example, a single metal such as chromium (Cr), aluminum (Al), molybdenum (Mo) or molybdenum tungsten (MoW) After depositing a film or a double metal film, the gate film is patterned by a photolithography process to form a gate wiring.

A gate insulating layer 140 made of silicon nitride is formed on the substrate 100 on which the gate wiring is formed to a thickness of about 4500 kW. A semiconductor film such as amorphous silicon is deposited on the gate insulating layer 140 and patterned by a photolithography process to form an active pattern 160 of the thin film transistor.

After depositing a metal film on the active pattern 160 and the gate insulating layer 140, the metal film is patterned by a photolithography process to form a data line. The data line includes a source electrode 200a, a drain electrode 200b, and a data pad (not shown) for transferring an image signal.

An inorganic protective film 220 made of silicon nitride is formed on the data line and the gate insulating layer 140 to a thickness of about 4000 μm, and then a photolithography process is performed on the source electrode 200b, on the gate line, and on the data pad. The inorganic protective layer 220 and the gate insulating layer 140 are dry-etched.

The contact hole 270 is formed on the surface of the inorganic passivation layer 220 to expose the source electrode 206 of the thin film transistor 200 ′.

The transparent electrode 280 is made of indium tin oxide (ITO) or indium zinc oxide (IZO), and has a predetermined thickness on the inorganic protective film 220. Therefore, the contact hole 270 formed in the inorganic passivation layer 220 is electrically connected to the source electrode 206 of the thin film transistor 200 ′.

The reflective electrode 290 is provided on the transparent electrode 280 having an isotropic polygonal shape protruding from the transparent electrode 280, and each reflective electrode 290 is provided to be spaced apart from each other without being in contact with each other. do.

The reflective electrode 290 is made of a metal having excellent reflectance such as aluminum (Al). In addition, the reflective electrode 290 is provided to have the same height from the transparent electrode 280 and the profile of the reflective electrode 290 are all the same.

Since the reflective electrode 290 has independent island shapes on the transparent electrode 280, the thin film transistor substrate 3000 receives light incident from the outside from a region provided with the reflective electrode 290. By the light generating means (not shown) provided below the insulating substrate 100 to the reflective region R for reflecting and the transparent electrode 280 which is not provided with the reflective electrode 290 and is exposed to the outside. A transmission area T for transmitting the light emitted is provided.

Therefore, when light is incident from the outside, the light is reflected by the reflective electrode, and the light emitted from the light generating means passes through the transparent electrode.

Here, the contact hole 270 is formed over the interface between the reflective window (R) and the transmission window (T).

That is, the contact hole 270 may include an edge (a) of a region where the gate insulating layer 140 and the source electrode 200a overlap, a side surface (b) of the source electrode extending from the edge (a), and a part of the gate insulating layer It is formed in contact with the region (c).

5 illustrates a-si type thin film transistor substrate according to another exemplary embodiment of the present invention.

Referring to FIG. 5, as a gate film on a transparent substrate 100 made of glass, quartz or sapphire, for example, a single metal such as chromium (Cr), aluminum (Al), molybdenum (Mo), or molybdenum tungsten (MoW) After depositing a film or a double metal film, the gate film is patterned by a photolithography process to form a gate wiring.

The contact hole 270 is formed on the surface of the inorganic passivation layer 220 to expose the source electrode 206 of the thin film transistor 200 ′.

Here, the contact hole 270 is formed over the interface between the reflective window (R) and the transmission window (T).

That is, the contact hole 270 may include an edge (a) of a region where the gate insulating layer 140 and the source electrode 206 overlap each other, a side surface (b) of the source electrode extending from the edge (a), and a part of the gate insulating layer. It is formed with the area c as a bottom surface.

Even if a part of the gate insulating layer c is added to the bottom surface, the same result as that of the contact hole 270 shown in FIG. 4 is obtained.

Other structures except for the bottom of the contact hole 270 are the same as those described with reference to FIG. 4, and thus the rest of the description will be omitted.

By taking such a structure, the area of the contact hole 270 may be reduced to 1/2, thereby increasing the reflectance, and not affecting the transmittance without increasing the area of the reflecting window.

According to the above-described thin film transistor substrate, the contact hole is formed so that both the source electrode and the interlayer insulating film or gate insulating film are exposed.

That is, by forming a contact hole at the boundary between the reflective window and the transmission window of the thin film transistor substrate, the reflectance of the light can be improved and ultimately the display quality can be improved.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (8)

An active pattern formed on the insulating substrate; A gate insulating film formed on the insulating substrate and the active pattern; A gate electrode formed on the gate insulating film; An interlayer insulating film formed on the gate electrode and the gate insulating film; Source / drain electrodes formed on both sides of the region where the active pattern and the gate insulating layer overlap by patterning the interlayer insulating layer; A protective film formed on the source / drain electrodes and the interlayer insulating film and having a contact hole partially exposing the source electrode and the interlayer insulating film; And And a reflective electrode formed on the passivation layer in a predetermined pattern and having a plurality of transmission windows including a partial region of the contact hole. The thin film transistor substrate of claim 1, wherein the transmission window includes a region that exposes the interlayer insulating layer of the contact hole. The thin film transistor substrate of claim 1, wherein the contact hole is formed with an edge of a region where the interlayer insulating layer and the source electrode overlap and a side surface of a source electrode extending from the edge as a bottom surface. The thin film transistor substrate of claim 3, wherein the bottom surface further comprises a portion of an interlayer insulating layer. A gate electrode formed on the insulating substrate; A gate insulating film formed on the insulating substrate and the gate electrode; Source / drain electrodes formed on both sides of regions where the gate electrode and the gate insulating layer overlap with each other; A protective film formed on the source / drain electrode and the gate insulating film and having a contact hole partially exposing the source electrode and the gate insulating film; And And a reflective electrode formed on the passivation layer in a predetermined pattern and having a plurality of transmission windows including a partial region of the contact hole. The thin film transistor substrate of claim 5, wherein the transmission window comprises a region exposing a gate insulating layer of the contact hole. The thin film transistor substrate of claim 5, wherein the contact hole is formed with an edge of a region where the gate insulating layer and the source electrode overlap and a side surface of a source electrode extending from the edge as a bottom surface. The thin film transistor substrate of claim 7, wherein the bottom surface further includes a portion of the gate insulating layer.