KR20070119899A - Tft, method for manufacturing of the same, liquid crystal display using the same and method for manufacturing of the same - Google Patents

Abstract

A thin film transistor, a fabrication method thereof, an LCD using the same, and a fabrication method thereof are provided to improve mobility of carriers and remove a need for an additional process for crystallization by using a nanowire for a semiconductor layer. A gate electrode(111) is formed on a predetermined portion on a substrate(110). A gate dielectric layer(112) is formed on the entire substrate including the gate electrode. A semiconductor layer(120) is formed on the gate electrode on the gate dielectric layer, and is formed of a nano material. A fixing plate(121) is formed at a central portion on the semiconductor layer. A source electrode(130) and a drain electrode(131) are formed at a predetermined interval at both sides of the semiconductor layer. The nano material is one of a nanowire, a nanocable, and a nanotube.

Description

Thin film transistor and method for manufacturing same, liquid crystal display using same and method for manufacturing same {TFT, Method For Manufacturing of The Same, Liquid Crystal Display Using The Same and Method For Manufacturing of The Same}

1 is a plan view showing a general liquid crystal display device

2A through 2F are cross-sectional views illustrating a method of manufacturing a conventional liquid crystal display device.

3 is a plan view showing a liquid crystal display device of the present invention.

4 is a cross-sectional view showing a liquid crystal display device of the present invention.

5A to 5H are cross-sectional views illustrating a process of manufacturing the liquid crystal display device of the present invention.

<Name of main part of drawing>

41, 110: substrate 42, 111: gate electrode

43, 112: gate insulating film 44a, 120: semiconductor layer

121: fixed plate 46, 130: source electrode

47, 131: drain electrode

The present invention relates to a thin film transistor, a method for manufacturing the same, a liquid crystal display using the same and a method for manufacturing the same.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELD), and vacuum fluorescent (VFD) Various flat panel display devices such as displays have been studied, and some of them are already used as display devices in various devices.

Among them, LCD is the most widely used as the substitute for CRT (Cathode Ray Tube) for mobile image display device because of its excellent image quality, light weight, thinness, and low power consumption. In addition to the use of the present invention has been developed in various ways such as a monitor of a television and a computer for receiving and displaying broadcast signals.

A general liquid crystal display device may be largely divided into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel, wherein the liquid crystal panel includes first and second glass substrates bonded to each other with a predetermined space; It consists of a liquid crystal layer injected between the said 1st, 2nd glass substrate.

Here, the first glass substrate (TFT array substrate) has a plurality of gate lines arranged in one direction at regular intervals, a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines, A plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing a gate line and a data line, and a plurality of thin film transistors switched by signals of the gate line to transfer the signal of the data line to each pixel electrode. Is formed.

In the second glass substrate (color filter array substrate), a light shielding layer for blocking light in portions other than the pixel region, an R, G, and B color filter layer for expressing color colors are common to implement an image. An electrode is formed.

The first and second substrates are bonded to each other by a seal material having a predetermined space by a spacer and having a liquid crystal injection hole to inject liquid crystal between the two substrates.

In the meantime, the thin film transistor uses a semiconductor film as an active layer. The semiconductor film is formed of amorphous silicon or crystalline silicon. The semiconductor film formed of amorphous silicon, which can be produced relatively easily by vapor deposition at low temperature and is suitable for mass production, was most widely used.

However, the thin film transistor including the semiconductor film formed of the crystalline silicon has sufficient driving capability for a large current to realize high speed operation, and allows the peripheral driving circuit of the LCD to be formed integrally with the display portion on the same substrate. For these reasons, thin film transistors containing crystalline silicon are attracting attention today.

1 is a plan view illustrating a general liquid crystal display device.

As shown in FIG. 1, a plurality of gate lines 11 are arranged in one direction at regular intervals to define the pixel region P on the lower substrate 10, and are perpendicular to the gate lines 11. The plurality of data lines 12 are arranged at regular intervals in the direction.

Each pixel region P defined by crossing the gate line 11 and the data line 12 is switched by a pixel electrode 16 formed in a matrix form and a signal of the gate line 11, A plurality of thin film transistors for transmitting a signal of the data line 12 to the pixel electrodes 16 are formed.

Here, the thin film transistor is formed on the gate electrode 13 protruding from the gate line 11, the gate insulating film (not shown) formed on the front surface, and the gate insulating film above the gate electrode 13. And a source electrode 15a formed to protrude from the data line 12, and a drain electrode 15b formed at regular intervals on the source electrode 15a. .

The drain electrode 15b is electrically connected to the pixel electrode 16 through the contact hole 17.

Meanwhile, the lower substrate 10 configured as described above has a predetermined space and is bonded to the upper substrate (not shown).

In this case, the upper substrate has an opening corresponding to the pixel region P formed in the lower substrate 10, and serves as a light blocking layer, and a red / green / color for implementing color. In addition to the blue (R / G / B) color filter layer and the pixel electrode (reflection electrode) 16, a common electrode for driving a liquid crystal is included.

The lower substrate 10 and the upper substrate as described above have liquid crystals injected between two substrates having a predetermined space by spacers and bonded by a seal material having a liquid crystal injection hole.

Hereinafter, a manufacturing method of a conventional liquid crystal display device will be described with reference to the accompanying drawings.

2A through 2F are cross-sectional views illustrating a method of manufacturing a conventional liquid crystal display device.

As shown in FIG. 2A, the sputtering method is selected from a metal made of Al, Al-Pd, Al-Si, Al-Si-Ti, Al-Si-Cu, Al alloy, or the like on the transparent glass substrate 41. Thereby depositing a metal film at a thickness of 200 to 4000 kPa.

Subsequently, the metal film is selectively etched through a photo and etching process to form a gate electrode 42 on the glass substrate 41.

Here, when the gate electrode 42 is a metal capable of anodizing, the gate electrode 42 may be anodized to prevent hillock.

As shown in FIG. 2B, a gate insulating film 43 made of a silicon nitride film or a silicon oxide film is formed on the entire surface of the glass substrate 41 including the gate electrode 42.

Subsequently, an amorphous silicon layer (a-Si layer) 44 and an ohmic contact layer (n +) 45 are sequentially formed on the gate insulating layer 43.

Meanwhile, the amorphous silicon layer 44 may be crystallized.

As shown in FIG. 2C, the ohmic contact layer 45 and the amorphous silicon layer 44 are selectively removed through photo and etching processes to form the active layer 44a.

Here, the active layer 44a is formed to cover the gate electrode 42 and surround the gate electrode 42.

As shown in FIG. 2D, a metal film is deposited on the entire surface of the glass substrate 41, and the source film 46 and the drain electrode 47 are electrically separated by selectively removing the metal film through a photo and etching process. To form.

Here, the etching of the metal film to form the source electrode 46 and the drain electrode 47 uses a wet etch process.

In addition, the source electrode 46 and the drain electrode 47 use a conductive metal film such as aluminum (Al), chromium (Cr), or molybdenum (Mo).

The ohmic contact layer 45 exposed between the source electrode 46 and the drain electrode 47 is selectively removed by dry etching.

In this case, when the ohmic contact layer 45 is removed, the active layer 44a beneath it is also removed by a predetermined thickness. That is, when the ohmic contact layer 45 is removed, damage is applied to the active layer 44a.

As shown in FIG. 2E, a protective film 48 is formed on the entire surface of the glass substrate 41 including the source electrode 46 and the drain electrode 47, and the surface of the drain electrode 47 is exposed to a predetermined portion. The protective layer 48 is selectively removed to form the contact hole 49.

As shown in FIG. 2F, a transparent metal film is deposited on the entire surface of the glass substrate 41 including the contact hole 49, and then selectively removed through the contact hole by a photo and etching process. The pixel electrode 50 is electrically connected to the drain electrode 47.

In addition, when polysilicon having a crystal phase is used as the active layer 44a, a polysilicon thin film transistor may be manufactured.

However, the liquid crystal display including the amorphous silicon thin film transistor and the polysilicon thin film transistor according to the prior art has the following problems.

That is, the amorphous silicon thin film transistor is not suitable for forming a transistor element of a driving circuit requiring fast operating characteristics because of low carrier mobility.

In addition, in the case of the polysilicon thin film transistor, the mobility of the carrier is 10 to 100 times higher than that of the amorphous silicon thin film transistor, so that a driving circuit may be formed on the substrate, which is advantageous as a switching device of a high resolution panel. However, in order to form a polysilicon thin film on a substrate, there is a problem in that an amorphous silicon thin film is first formed through a low temperature CVD process and an additional process for crystallization such as irradiating a laser beam is required.

The present invention is to solve the conventional problems as described above, and to provide a thin film transistor, a manufacturing method thereof and a liquid crystal display device and a manufacturing method thereof, which does not require an additional process for crystallization while increasing the mobility of the carrier. There is this.

The thin film transistor according to the present invention according to the above object is a substrate, a gate electrode formed on a predetermined portion of the substrate, a gate insulating film formed on the front surface of the substrate including the gate electrode, a semiconductor formed on the gate electrode and made of a nanomaterial And a source plate and a drain electrode formed at regular intervals on both sides of the layer, a fixed plate formed at a central portion of the semiconductor layer, and both sides of the semiconductor layer.

The liquid crystal display according to the present invention according to the above object is a substrate, a gate electrode formed on a predetermined portion of the substrate, a gate insulating film formed on the entire surface of the substrate including the gate electrode, formed on the gate electrode on the gate insulating film nano A protective layer having a semiconductor layer made of a material, a source electrode and a drain electrode formed at regular intervals on both sides of the semiconductor layer, and a substrate including the semiconductor layer, the source electrode, and the drain electrode, and having a contact hole on the drain electrode. And a pixel electrode contacting the drain electrode through the contact hole and formed on the passivation layer.

According to an aspect of the present invention, a method of manufacturing a thin film transistor includes forming a gate electrode on a predetermined portion of a substrate, forming a gate insulating film on the entire surface of the substrate including the gate electrode, and a gate electrode on the gate insulating film. Forming a semiconductor layer formed of a nanomaterial on the upper surface, forming a fixing plate on a central portion of the upper portion of the semiconductor layer, and forming source and drain electrodes having a predetermined interval on both sides of the semiconductor layer; do.

According to an aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, including forming a gate electrode on a predetermined portion of a substrate, forming a gate insulating film on the entire surface of the substrate including the gate electrode, and forming a gate on the gate insulating film. Forming a semiconductor layer formed of nanowires on an electrode, forming a photosensitive polymer layer on the semiconductor layer, placing a mask on the photosensitive polymer layer, and patterning the photosensitive polymer layer using the mask to form the semiconductor layer Forming a fixing plate at a portion corresponding to a central portion, forming a source electrode and a drain electrode having a predetermined interval on both sides of the nanowire, and forming a protective film on the entire surface of the substrate including the semiconductor layer, the source electrode, and the drain electrode Step, the upper portion of the drain electrode in the protective film The method may include forming a contact hole in a portion of the portion, and forming a pixel electrode on an upper portion of the drain electrode of the portion where the contact hole is formed and an upper portion of the passivation layer.

3 and 4 illustrate one embodiment of the present invention. FIG. 3 is a plan view showing a liquid crystal display device according to the present invention, and FIG. 4 is a cross-sectional view showing a liquid crystal display device taken along line II ′ of FIG. 3.

As shown in FIGS. 3 and 4, the thin film transistor according to the present invention includes a glass substrate 110 of a transparent material, a gate electrode 111 formed on a predetermined portion of the substrate 110, and the gate electrode 111. A gate insulating layer 112 formed on the entire surface of the substrate 110, including a semiconductor layer 120 formed on the gate electrode 111 on the gate insulating layer 112 and formed of nanowires, on both sides of the semiconductor layer 120. And a fixing plate 121 formed on the semiconductor layer 120 between the source electrode 130 and the drain electrode 131 having a predetermined interval and between the semiconductor layer 120 and the source / drain electrodes 130 and 131. have.

Subsequently, the liquid crystal display of the present invention according to the above object is formed on the entire surface of the substrate 110 including the semiconductor layer 120 and the source / drain electrodes 130 and 131 as shown in FIGS. 3 and 4. The passivation layer 140 including the contact hole 141 on the drain electrode 131 and the pixel electrode 142 formed on the passivation layer 140 in contact with the drain electrode 131 through the contact hole 141. It is configured to include more.

Hereinafter, a manufacturing method of the liquid crystal display device of the present invention will be described in detail with reference to the accompanying drawings.

5A to 5H are cross-sectional views showing an embodiment of the liquid crystal display of the present invention.

First, the manufacturing method of the liquid crystal display device of the present invention, as shown in Figure 5a, on a transparent glass substrate 110, copper (Cu), aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), chromium ( A low resistance metal material such as Cr) is deposited and patterned in at least one or more layers to form a gate wiring (not shown) and a gate electrode 111 branching from the gate wiring.

In addition, an insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx) is deposited on the entire surface including the gate electrode 111 to form a gate insulating layer 112. Next, a Zn metal nanoparticle is formed on the surface of the gate electrode 111 on the gate insulating layer 112, and Zn metal is formed on the surface by oxidizing the granulated Zn particles in air and at atmospheric pressure. The semiconductor layer 120 is formed in the direction of the source and drain to be formed later.

The nanowires may be formed on the substrate 110 in various ways. That is, for example, there is a laser induced thermal imaging method (hereinafter referred to as "LITI method").

First, in the present invention, a method of forming active layers having nanoparticles according to the LITI method uses a donor sheet. This donor sheet arranges the said nanowire in the film parallel to the longitudinal direction, and forms a transfer layer. The film includes a base film serving as a substrate and a light to heat conversion layer (LTHC layer). The base film may be a polyolefin resin.

In addition, the light-to-heat conversion layer may be coated on the base film by stirring carbon in acryl, but is not necessarily limited thereto, and converts the light of the laser into heat to apply heat to the transfer layer to transfer the transfer layer, Anything that can cause the ablation of the laser can be used.

The donor sheet is seated on the substrate 110 and laminated to each other to be temporarily bonded. In this state, when a laser beam is irradiated to a predetermined portion to form a pattern and the donor sheet and the substrate 110 are separated, nanowires are formed on the substrate 110.

As illustrated in FIG. 5B, a negative photosensitive polymer layer 121a is deposited on the entire surface of the substrate 110 on the gate insulating layer 112 including the semiconductor layer 120. Here, the photosensitive polymer refers to a functional polymer that causes a bridging reaction or insolubilization by light, among polymers that are chemically or physically changed by the action of light. Photoacryl may be used.

Forming the negative type photosensitive polymer layer 121a on the semiconductor layer 120 made of the nanowires in the photo process step for forming the fixing plate 121 will be described in detail. As an example, the present invention is not limited to the above embodiment, and it is also possible to form a positive type photosensitive polymer layer. However, when the positive type is used, the part where the light is not exposed disappears and the part where the light is not exposed is considered. Therefore, the mask pattern should be reversed compared to the case where the negative type is used.

As shown in FIG. 5C, a portion of the fixing plate is formed as an opening portion, and a mask 150 made by coating a chromium thin film is placed in a stepper, which is an exposure equipment, such as UV and x-ray wavelengths. ) Is selectively exposed to the photosensitive polymer layer 121a for exposure. At this time, the light irradiated to the photosensitive polymer layer 121a through the opening of the mask 150 reaches a portion where the fixing plate is to be formed, and the portion where the chromium thin film is coated does not pass.

As shown in FIG. 5D, the selectively exposed photosensitive polymer layer 121a is developed with a developer to form the fixing plate 121.

Here, since the photosensitive polymer layer 121a is a negative type, a portion that receives light is left and a portion that does not receive light is removed.

As shown in FIG. 5E, copper (Cu), aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), and chromium (Cu) are formed on the entire surface of the substrate on the gate insulating layer 112 including the fixing plate 121 and the semiconductor layer 120. The semiconductor layer 120 is formed by depositing any one of low-resistance metal materials such as Cr), titanium (Ti), tantalum (Ta), and molybdenum-uranium (MoW) by a sputtering method and applying a photoetch process. Source / drain electrodes 130 and 131 are spaced apart from each other by a predetermined distance at both ends.

As illustrated in FIG. 5F, inorganic materials SiNx and SiO ₂ are deposited on the entire surface of the substrate 110 on the gate insulating layer 112 including the fixing plate 121 and the source / drain electrodes 130 and 131 by chemical vapor deposition or organic vapor deposition. BCB (Benzocyclobutene) and acrylic resin (acryl resin) is applied to form a protective film 140.

As illustrated in FIG. 5G, the protective layer 140 is selectively etched to expose a portion of the drain electrode 131 to form a contact hole 141.

As shown in FIG. 5H, indium tin oxide (ITO) is disposed on the upper portion of the drain electrode 131 of the portion where the contact hole 141 is formed and the protective layer 140 around the drain electrode 131 so that the surface of the drain electrode 131 is exposed to a predetermined portion. Alternatively, an indium zinc oxide (IZO) or the like is deposited and patterned to form a pixel electrode 142 in the pixel region to be in contact with the drain electrode 131 through the contact hole 141.

The gate electrode 111, the gate insulating film 112, the semiconductor layer 120, the fixing plate 121, the source / drain electrodes 130 and 131, the passivation layer 140, and the pixel electrode are disposed on a predetermined portion of the substrate 110. A liquid crystal display device composed of the laminated film of 142 is completed.

In the forming of the fixing plate 121 of the present invention, the fixing plate 121 is formed at an intermediate position of the semiconductor layer 120 so that there is a problem in contact between the semiconductor layer 120 and the source / drain electrodes 130 and 131. It should not happen. This is because when the fixing plate 121 is biased toward one end of the semiconductor layer 120, the contact between the semiconductor layer 120 and the source electrode 130 or the drain electrode 131 may not occur. . Therefore, the fixing plate 121 is preferably formed at an intermediate position of the semiconductor layer.

The length of the fixing plate 121 should be shorter than the length of the semiconductor layer 120 so that the contact between the semiconductor layer 120 and the source / drain electrodes 130 and 131 does not occur. In addition, the length of the fixing plate 121 should be at least greater than the distance between the source electrode 130 and the drain electrode 131. This is to protect the semiconductor layer 120 by acting as an etch stopper in the process of etching the source / drain electrodes 130 and 131.

In the above description, the nanowires used as semiconductor layers are limited to ZnO nanowires. However, the present invention is not limited thereto and may be applied to Si nanowires, GaN nanowires, Ge nanowires, and InP nanowires. It is possible that the various embodiments of the technical idea belong to the protection scope of the present invention.

In addition, the above description has been made with limited use of nanowires as semiconductor layers, but various modifications are possible, including but not limited to nanomaterials such as nanocables and carbon nanotubes. Of course, all the various embodiments of the technical idea belong to the protection scope of the present invention.

The carbon nanotubes are fine molecules having a diameter of 1 nanometer (one nanometer is one billionth of a meter) in which carbons connected by hexagonal rings form a long shape. The carbon plane, which has three carbon atoms bonded together and has a honeycomb structure, is rolled up to form a tube. It is a futuristic new material with 100 times stronger tensile strength than steel and excellent flexibility. It is known to be hollow, lightweight, electricity is as good as copper, and thermal conductivity is as good as diamond. Carbon nanotubes are attracting attention as the next generation of semiconductor materials as it turns out to be conductors and semiconductors depending on the diameter of the tube.

The nano cable is in the shape of a nano-sized coaxial cable, and the cross section of the line is concentric. According to the present invention, since the inside is made of a semiconductor to form a channel connecting the source electrode and the drain electrode, and the outside is made of an insulator, which does not require the formation of a separate insulator. .

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is a technology that the various permutations, modifications and changes that can be made within the scope without departing from the spirit of the present invention It will be apparent to those of ordinary skill in the art.

As described above, the thin film transistor according to the present invention, a manufacturing method thereof, a liquid crystal display using the same, and a manufacturing method thereof have the following effects.

First, by using nanowires as a semiconductor layer, carrier mobility can be increased as compared to an amorphous silicon thin film transistor, and it does not require an additional process for crystallization like a polysilicon thin film transistor.

Second, by forming the fixing plate on the nanowires used as the semiconductor layer, it is possible to improve the bonding property of the nanowires by solving a problem such as the position of the nanowires being changed or falling from the gate insulating film by a subsequent process.

Third, by forming the fixing plate on the nanowire used as the semiconductor layer, there is an effect of solving the problem of adversely affecting the nanowire by an etchant in a subsequent process such as external contamination, source, or drain etching. .

Claims (13)

Board; A gate electrode formed on a predetermined portion of the substrate; A gate insulating film formed on an entire surface of the substrate including the gate electrode; A semiconductor layer formed on the gate electrode on the gate insulating layer and made of a nanomaterial; A fixing plate formed at a central portion of the upper portion of the semiconductor layer; And The thin film transistor comprising a source electrode and a drain electrode formed at regular intervals on both sides of the semiconductor layer. The method of claim 1, The nanomaterial is a thin film transistor, characterized in that made of any one of nanowires, nano cables and nanotubes. The method of claim 1, The length of the fixing plate is greater than the distance between the source / drain electrode, the thin film transistor, characterized in that less than the length of the nanowires. Board; A gate electrode formed on a predetermined portion of the substrate; A gate insulating film formed on an entire surface of the substrate including the gate electrode; A semiconductor layer formed on the gate electrode on the gate insulating layer and made of a nanomaterial; Source and drain electrodes formed at regular intervals on both sides of the semiconductor layer; A passivation layer formed on an entire surface of the substrate including the semiconductor layer, the source electrode, and the drain electrode, and having a contact hole on the drain electrode; And And a pixel electrode in contact with the drain electrode through the contact hole and formed on the passivation layer. The method of claim 4, wherein The nanomaterial is made of any one of nanowires, nano cables and nanotubes. Forming a gate electrode on a predetermined portion of the substrate; Forming a gate insulating film on an entire surface of the substrate including the gate electrode; Forming a semiconductor layer formed of a nanomaterial on the gate electrode on the gate insulating layer; Forming a fixing plate on a central portion of the upper portion of the semiconductor layer; And And forming a source electrode and a drain electrode having a predetermined interval on both sides of the semiconductor layer. The method of claim 6, The nanomaterial is a method of manufacturing a thin film transistor, characterized in that formed using any one of nanowires, nano cables and nanotubes. The method of claim 6, Forming the photosensitive polymer layer on the front surface of the substrate including the semiconductor layer; And And patterning the photosensitive polymer layer by exposing and developing the photosensitive polymer layer. The method of claim 8, The photosensitive polymer layer is a method of manufacturing a thin film transistor, characterized in that using a photo acrylic film. Forming a gate electrode on a predetermined portion of the substrate; Forming a gate insulating film on an entire surface of the substrate including the gate electrode; Forming a semiconductor layer made of a nanomaterial on the gate electrode on the gate insulating film; Forming a fixing plate on a central portion of the upper portion of the semiconductor layer; Forming source and drain electrodes at regular intervals on both sides of the semiconductor layer; Forming a protective film on an entire surface of the substrate including the semiconductor layer, the source electrode, and the drain electrode; Forming a contact hole in a portion of the passivation layer corresponding to an upper portion of the drain electrode; And forming a pixel electrode on an upper portion of the drain electrode of the portion where the contact hole is formed and an upper portion of the protective layer around the drain electrode. The method of claim 10, The nanomaterial is a method of manufacturing a liquid crystal display device, characterized in that consisting of any one of nanowires, nano cables and nanotubes. The method of claim 10, wherein the fixing plate Forming a photosensitive polymer layer on an entire surface of the substrate including the semiconductor layer; And Exposing and developing the photosensitive polymer layer to pattern the liquid crystal display device. The method of claim 12, The photosensitive polymer layer is a manufacturing method of the liquid crystal display device, characterized in that using a photo acrylic film.

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