KR100626032B1 - Method of manufacturing thin film transistor, thin film transistor manufactured by the method, method of manufacturing flat panel display device, and flat panel display device manufactured by the method - Google Patents

Abstract

The present invention is to provide a thin film transistor on a plastic substrate to be applied to a flexible device, for this purpose, forming an etching stopper layer on the substrate, a source electrode and a drain electrode on the etching stopper layer Forming a semiconductor layer in contact with the source electrode and the drain electrode, forming a gate insulating film to cover the semiconductor layer, forming a gate electrode on the gate insulating film; Forming an insulating film to cover the gate electrode and the gate insulating film, bonding a plastic substrate corresponding to the substrate on the insulating film, and removing the substrate. Method of manufacturing a substrate, a substrate having a thin film transistor manufactured accordingly, a flat plate It provides the manufacturing method, and hence the flat panel display manufactured according jangchieul market value.

Description

A method of manufacturing a substrate having a thin film transistor, a substrate having a thin film transistor manufactured according to the same, a method of manufacturing a flat panel display device, and a flat panel display device manufactured according to the method. method, method of manufacturing flat panel display device, and flat panel display device manufactured by the method}

1 to 7 are cross-sectional views schematically illustrating manufacturing processes of a thin film transistor provided on a plastic substrate according to an exemplary embodiment of the present invention;

8 and 9 are cross-sectional views illustrating a process of manufacturing an organic light emitting display device using a substrate manufactured by the method of FIGS. 1 to 7.

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

10 substrate 20 etching stopper layer

30: conductive film 31: source electrode

32: drain electrode 33: semiconductor layer

34: gate insulating film 35: gate electrode

36: insulating film 41: pixel electrode

42: organic layer 43: counter electrode

50: plastic substrate

The present invention relates to a method of manufacturing a substrate having a thin film transistor, a substrate having a thin film transistor manufactured according to the present invention, a method of manufacturing a flat panel display device, and a flat panel display device manufactured according to the present invention. To a method of manufacturing a substrate having a thin film transistor that can be applied to a flexible device, a substrate having a thin film transistor manufactured according to the present invention, a method of manufacturing a flat panel display device, and a flat panel display device manufactured accordingly. It is about.

Liquid crystal displays (LCDs) and electroluminescence displays (ELDs) with low-temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) are currently available for digital cameras and video. The market is expanding to display for mobile devices such as cameras, PDAs, and cellular phones.

The first characteristic of the low temperature polycrystalline silicon thin film transistor is that the electron mobility of the low temperature polycrystalline silicon is more than 100 times that of amorphous silicon, so that the current driving capability of the thin film transistor is high, and the size of the thin film transistor formed in each pixel is increased. It can be reduced. Therefore, it is possible to reduce the pixel size, that is, high definition, so that the panel can be miniaturized, which is optimal for display for mobile devices.

The second characteristic is that the ON current ratio of each transistor of the N-channel and P-channel is balanced by factor 2, and the CMOS circuit can be configured. Therefore, a CMOS circuit can be integrated into a thin film transistor on the outer periphery of the panel, and the image signal input from the outside of the panel is once received therein and converted into a drive signal for data wiring and gate wiring connected to each pixel. Compared to the amorphous silicon thin film transistors that need to supply a signal, the number of input pins on the panel can be reduced. This is effective for improving reliability or impact resistance.

On the other hand, thinner, lighter and more unbreakable features are required for mobile applications. In order to manufacture thin and light, in addition to the method of using a thin glass substrate in the manufacturing, a method of making a thin glass substrate by a mechanical or chemical method after the production using an existing glass substrate was introduced. However, such a process is not only complicated but also can be easily broken, which makes it difficult to use practically.

In order to solve this problem, an attempt has been made to form a low temperature polycrystalline silicon thin film transistor on a plastic substrate. Even if the plastic is formed to a thickness of about 0.2 mm, it is hard to be broken, and its specific gravity is smaller than that of glass, so that the weight can be reduced to 1/5 or less compared to the existing glass substrate, and the flexible display can be realized. have.

However, when fabricating a low temperature polycrystalline silicon thin film transistor, the temperature of the substrate is raised to 400 to 500 ° C., which is a problem when using a plastic substrate. The heat resistant temperature of the transparent plastic substrate, such as polycarbonate (PC) or polyethylsulfone (PES), is about 200 ° C to 300 ° C, which is much lower than the glass substrate. In addition, even when a polycrystalline silicon thin film transistor is manufactured using the plastic substrate as described above at a heat resistance temperature, the coefficient of thermal expansion (linear expansion coefficient) of the plastic substrate is 50 ppm / ° C. or higher. There was a problem that expansion caused by% may cause patterning errors, disconnection of wiring, and the like.

In order to solve this problem, the March 2004 issue of Monthly Display, published in Japan, includes a thin film transistor on a plastic substrate by using the transfer method twice under the title of the latest trend of plastic substrate low temperature polycrystalline silicon thin film transistor LCD. How to do it is posted.

This method forms an etching stopper layer on an existing glass substrate, and then forms a low temperature polycrystalline silicon thin film transistor on the etching stopper layer according to an existing method. The temporary substrate is attached onto the thin film transistor with a temporary adhesive or the like, and the glass substrate and the etching stopper layer are removed using hydrofluoric acid (HF) or the like. After the above process, the plastic substrate is attached to the lower surface of the thin film transistor with an adhesive, and finally, the temporary substrate is peeled off to manufacture the thin film transistor provided on the plastic substrate.

However, the above manufacturing method has a problem that the process is too complicated, such as transferring twice using a temporary substrate, and also in the process of forming an electroluminescent element or the like on the thin film transistor manufactured by the above method. There is a problem that the process is overly complex and the same process is repeated.

The present invention is to solve the various problems including the above problems, the method of manufacturing a substrate having a thin film transistor provided on a plastic substrate, which can be applied to a flexible device, a thin film transistor manufactured according to the An object of the present invention is to provide a substrate, a method of manufacturing a flat panel display, and a flat panel display manufactured accordingly.

In order to achieve the above object and various other objects, the present invention provides a method for forming an etching stopper layer on a substrate, forming a source electrode and a drain electrode on the etching stopper layer, and And forming a semiconductor layer in contact with the drain electrode, forming a gate insulating film to cover the semiconductor layer, forming a gate electrode on the gate insulating film, and covering the gate electrode and the gate insulating film. A method of manufacturing a substrate having a thin film transistor, the method comprising forming an insulating film, bonding a plastic substrate corresponding to the substrate on the insulating film, and removing the substrate.

The present invention also provides a substrate having a thin film transistor manufactured according to this manufacturing method.

The present invention also provides a method for forming an etch stopper layer on a substrate, forming a pixel electrode on the etch stopper layer, and a source electrode and a drain electrode on the etch stopper layer. Forming a semiconductor layer in contact with the source electrode and the drain electrode, forming a gate insulating film to cover the pixel electrode and the semiconductor layer, and forming a gate electrode on the gate insulating film. Forming an insulating film so as to cover the gate electrode and the gate insulating film, bonding a plastic substrate corresponding to the substrate on the insulating film, removing the substrate, and removing the pixel electrode. Forming openings in the etching stopper layer to expose regions, and pixel electrodes exposed through the openings It provides a process for the production of parts and a flat panel display device comprising the step of forming the display elements on the lower etching stopper layer.

The present invention also provides a flat panel display manufactured according to this manufacturing method.

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

1 to 7 are views sequentially showing a method of manufacturing a substrate having a thin film transistor according to an embodiment of the present invention, Figures 8 and 9 is a preferred embodiment of the present invention using this substrate FIG. 4 is a diagram illustrating a method of manufacturing a flat panel display device.

First, referring to FIGS. 1 to 7, the etching stopper layer 20 is formed on the substrate 10, which is relatively easy to handle, and the thin film transistor TFT and the pixel electrode 41 are formed on the etching stopper layer 20. To form.

The substrate 10 may be an existing glass substrate, but is not necessarily limited thereto. If the substrate 10 has a certain thickness, the substrate 10 may be easily handled during the process, and the substrate may withstand the temperature of the process. And synthetic resin materials.

The etching stopper layer 20 formed on the substrate 10 acts as a stopper layer for this etching when etching the substrate 10 with hydrofluoric acid (HF) or the like, as described later. Any material may be used as long as it has a stopper function for etching.

The conductive film 30 is formed on this etching stopper layer 20 as shown in FIG.

As described later, the conductive layer 30 may form the pixel electrode 41, and may be formed of a single layer or a plurality of conductive materials.

The conductive film 30 may be formed of ITO, IZO, ZnO, or In 2 O 3 when the pixel electrode 41 is used as a transparent electrode, and Ag, Mg, After forming a reflective film with Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, a compound thereof, or the like, ITO, IZO, ZnO, or In 2 O 3 can be formed thereon. Of course, in addition to that can be used, such as a conductive polymer.

After the conductive film 30 is formed, as shown in FIG. 2, the conductive film 30 is patterned to form the source electrode 31 and the drain electrode 32.

At this time, according to the preferred embodiment of the present invention, the pixel electrode 41 is also formed at the same time as these source and drain electrodes 31 and 32. In addition, the drain electrode 32 and the pixel electrode 41 may be integrally connected. However, the present invention is not necessarily limited thereto, and only the pixel electrode 41 may be formed on the etching stuffer layer 20, the insulating film may be covered thereon, and the source and drain electrodes 31 and 32 may be formed on the insulating film. have.

After the pixel electrode 41 and the source and drain electrodes 31 and 32 are formed, as shown in FIG. 3, the semiconductor layer 33 is formed to cover the source and drain electrodes 31 and 32. do.

The semiconductor layer 33 may be an organic semiconductor or an inorganic semiconductor.

The organic semiconductor may be provided as a semiconducting organic material, and as a polymer, polythiophene and its derivatives, polyparaphenylenevinylene and its derivatives, polyparaphenylene and its derivatives, polyfluorene and its derivatives, Polythiophenevinylene and derivatives thereof, polythiophene-heterocyclic aromatic copolymers and derivatives thereof, and as low molecular weights, oligoacenes of pentacene, tetracene, naphthalene and derivatives thereof, alpha-6-ti Ophene, oligothiophenes of alpha-5-thiophene and derivatives thereof, phthalocyanine and derivatives thereof with or without metals, pyromellitic dianhydrides or pyromellitic diimides and derivatives thereof, fur Reylenetetracarboxylic acid dianhydride or perylenetetracarboxylic diimide and derivatives thereof.

In the case of using the organic semiconductor, after forming the organic semiconductor layer to cover the source electrode 31 and the drain electrode 32, it is partitioned so as to have an area as shown in FIG. 3 by a laser etching method (LAT). Of course, in addition to this, various patterning methods used in the organic semiconductor may be used as it is, and it is not necessary to pattern the region as shown in FIG.

The inorganic semiconductor may include CdS, GaS, ZnS, CdSe, CaSe, ZnSe, CdTe, SiC, and Si. According to a preferred embodiment of the present invention, as the semiconductor layer 33, polycrystalline silicon (poly Si) can be used. To this end, an amorphous silicon layer is formed on the source electrode 31 and the drain electrode 32 by chemical vapor deposition (CVD) or sputtering, or the like, and then the amorphous silicon layer is converted into a polycrystalline silicon layer. .

The polycrystallization process of the amorphous silicon layer is divided into a low temperature process and a high temperature process according to the process temperature. However, since the high temperature process requires a high temperature quartz substrate having a high thermal resistance due to a temperature condition above the deformation temperature of the substrate, a low temperature process is mainly used. The low temperature process can be classified into laser annealing, metal induced crystallization (MIC), etc., mainly by irradiating a laser to the amorphous silicon layer, melting it into a liquid phase, and cooling the grain to grow grain. Sequential lateral sequential crystallization, using the fact that excimer laser annealing, or grains of polycrystalline silicon, grows perpendicular to its interface at the boundary between the laser-irradiated liquid region and the non-irradiated solid-state region A polycrystalline silicon layer is formed using a lateral solidification process.

However, in the above-described crystallization step, even in the low temperature step, as described above, the step of 200 ° C to 300 ° C or more, which is the heat resistance temperature of the plastic substrate. In the present invention, by using the substrate 10 as a material that can withstand such a temperature without deformation, the amorphous silicon layer is easily converted into a polycrystalline silicon layer, and a plastic substrate can be used as described later.

After the polycrystallization of the amorphous silicon layer as described above, the polycrystalline silicon layer may be appropriately patterned, and the semiconductor layer may be ion implanted and activated to activate n-type or p-type impurities. It may be. This is also the same in the embodiments described later.

After the semiconductor layer 33 is formed, as shown in FIG. 4, the gate insulating layer 34 is formed to cover the remaining portions of the semiconductor layer 33, the pixel electrode 41, and the etching stopper layer 20.

An inorganic material and / or an organic material may be used for the gate insulating layer 34. As inorganic materials, SiO2, SiNx, Al2O3, TiO2, Ta2O5, HfO2, ZrO2, BST, PZT, etc. are possible, and as organic materials, general purpose polymers (PMMA, PS), polymer derivatives having phenol groups, acrylic polymers, imide polymers , Arylether polymers, amide polymers, fluorine polymers, p-xylene polymers, vinyl alcohol polymers and blends thereof. In addition, inorganic-organic laminated films are also possible.

As shown in FIG. 5, a gate electrode 35 having a predetermined pattern is formed on the gate insulating film 34. The gate electrode 35 is formed to correspond to the channel region of the semiconductor layer 33.

After the gate electrode 35 is formed, as shown in Fig. 5, an insulating film 36 is further formed to cover this TFT. The insulating film 36 protects the TFT and maintains the flatness when attaching the plastic substrate 50 thereon, as will be described later. The insulating layer 36 may be formed of an inorganic material and / or an organic material as a single layer or a composite layer. As the inorganic material, SiO 2, SiN x, Al 2 O 3, TiO 2, Ta 2 O 5, HfO 2, ZrO 2, BST, PZT, and the like may be used. General purpose polymers (PMMA, PS), polymer derivatives having phenol groups, acrylic polymers, imide polymers, arylether polymers, amide polymers, fluorine polymers, p-xylene polymers, vinyl alcohol polymers and blends thereof It is possible. However, the present invention is not limited thereto, and various insulating materials may be used.

As shown in FIG. 6, the plastic substrate 50 is bonded to the insulating film 36. The plastic substrate 50 may be bonded by various methods, and may be bonded with an adhesive interposed between the insulating film 36.

After bonding the plastic substrate 50, as shown in Figure 7, the substrate 10 is removed. The substrate 10 may be removed by a variety of methods, which may be removed by dry and wet etching.

In the substrate provided with the thin film transistor TFT described above, since the drain electrode 32 of the thin film transistor TFT is formed integrally with the pixel electrode 41, the drain electrode 32 through a separate contact hole. And pixel electrode 41 need not be connected.

After forming the plastic substrate 50 including the thin film transistor TFT by the above method, as shown in FIG. 8, a predetermined portion of the etching stopper layer 20 is etched to form a predetermined portion of the pixel electrode 41. The opening 21 is formed so that the part is exposed. Formation of the opening 21 is possible in various ways, the photolithography method can be applied.

As shown in FIG. 9, the organic layer 42 including the light emitting layer (not shown) is formed in the opening 21, and the counter electrode 43 is formed to cover the organic layer 42. (OLED) is formed.

The organic layer 42 may be a low molecular or high molecular organic layer.

In the case of a low molecular organic layer, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL) Electron Injection Layer, etc. may be formed by stacking a single or complex structure, and usable organic materials are copper phthalocyanine (CuPc), N, N-di (naphthalen-1-yl) -N, N ' -Diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum (Alq3) It can be used in various ways. These low molecular weight organic layers are formed by the vacuum deposition method.

In the case of the polymer organic layer, the structure may include a hole transporting layer (HTL) and a light emitting layer (EML). In this case, PEDOT is used as the hole transporting layer, and polyvinylvinylene (PPV) and polyfluorene are used as the light emitting layer. Polymer organic materials such as (Polyfluorene) are used and can be formed by screen printing or inkjet printing.

The counter electrode 43 may be provided as a transparent electrode or a reflective electrode. When used as a transparent electrode, a metal having a small work function, that is, Li, Ca, LiF / Ca, LiF / Al, Al, Mg, and a compound thereof is deposited to face the organic layer 42, and thereafter, ITO, The auxiliary electrode layer or the bus electrode line can be formed of a material for forming a transparent electrode such as IZO, ZnO, or In 2 O 3. And, when used as a reflective electrode can be formed by depositing the above Li, Ca, LiF / Ca, LiF / Al, Al, Mg, and compounds thereof.

According to the present invention, since the etching stopper layer 20 is a pixel define layer as it is, the flat panel display can be implemented by one transfer.

In the above-described embodiments, only the case of the active driving type electroluminescent device has been described. However, as described above, any display device having a thin film transistor may be applied to any device. It can also be applied to display elements such as TFT LCD).

In addition, the thin film transistor formed on the plastic substrate according to the present invention as described above is provided in all devices having a flexible thin film transistor, such as a flexible electronic sheet (smart card), other than the display device as described above. Of course it can be.

According to the present invention made as described above, the following effects can be obtained.

First, after the thin film transistor is formed on a substrate having a sufficient thickness, the thin film transistor formed on the thin plastic substrate is made simple by providing a plastic substrate having a desired thin thickness on the thin film transistor and removing the thick substrate. Can be obtained through the process.                     

Second, a polycrystalline silicon thin film transistor formed on a plastic substrate can be obtained.

Third, various flexible devices including a thin film transistor formed on a plastic substrate, particularly a flexible display device, can be manufactured.

Fourth, an electroluminescent device having a thin film transistor formed on a plastic substrate can be manufactured. In this case, by forming an pixel defining layer by patterning the etching stopper layer in the process, the process can be simplified and the cost can be reduced. have.

Fifth, since only one transfer process is required, the process is simplified.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (19)

delete Forming an etch stopper layer on the substrate; Forming a source electrode and a drain electrode on the etching stopper layer; Forming a pixel electrode on the etching stopper layer; Forming a semiconductor layer in contact with the source electrode and the drain electrode, respectively; Forming a gate insulating film to cover the semiconductor layer; Forming a gate electrode on the gate insulating film; Forming an insulating film to cover the gate electrode and the gate insulating film; Bonding a plastic substrate corresponding to the substrate on the insulating film; And Removing the substrate; Method of manufacturing a substrate having a thin film transistor comprising a. The method of claim 2, And the pixel electrode is formed at the same time as the source electrode and the drain electrode. The method of claim 2, The pixel electrode is formed to be connected to any one of the source electrode and the drain electrode. The method according to any one of claims 2 to 4, The semiconductor layer is a method of manufacturing a substrate having a thin film transistor, characterized in that formed of an organic or inorganic material. The method of claim 5, The organic material is pentacene, tetracene, tetratracene, anthracene, naphthalene, alpha-6-thiophene, alpha-4-thiophene, perylene and its derivatives, ru Rubrene and its derivatives, coronene and its derivatives, perylene tetracarboxylic diimide and its derivatives, perylene tetracarboxylic dianhydride and its derivatives Derivatives, oligoacenes and derivatives thereof of naphthalene, oligothiophenes and derivatives thereof of alpha-5-thiophene, phthalocyanine and derivatives thereof with or without metal, pyromellitic dianhydrides and derivatives thereof, A method of manufacturing a substrate with a thin film transistor, characterized in that it comprises at least one of pyromellitic diimide and derivatives thereof. The method of claim 5, And said inorganic material comprises at least one of CdS, GaS, ZnS, CdSe, CaSe, ZnSe, CdTe, SiC, and Si. The method according to any one of claims 2 to 4, The forming of the semiconductor layer may include applying an amorphous silicon layer and crystallizing the amorphous silicon layer into a polycrystalline silicon layer. The method according to any one of claims 2 to 4, The substrate is a method of manufacturing a substrate having a thin film transistor, characterized in that the glass substrate. A substrate having a thin film transistor, which is manufactured according to any one of claims 2 to 4. Forming an etch stopper layer on the substrate; Forming a pixel electrode on the etching stopper layer; Forming a source electrode and a drain electrode on the etching stopper layer; Forming a semiconductor layer in contact with the source electrode and the drain electrode, respectively; Forming a gate insulating film to cover the pixel electrode and the semiconductor layer; Forming a gate electrode on the gate insulating film; Forming an insulating film to cover the gate electrode and the gate insulating film; Bonding a plastic substrate corresponding to the substrate on the insulating film; Removing the substrate; Forming an opening in the etching stopper layer to expose a predetermined region of the pixel electrode; And And forming a display element under the pixel electrode exposed through the opening and under the etching stopper layer. The method of claim 11, And the pixel electrode is formed at the same time as the source electrode and the drain electrode. The method of claim 11, And the pixel electrode is connected to any one of the source electrode and the drain electrode. The method according to any one of claims 11 to 13, And the semiconductor layer is formed of an organic or inorganic material. The method of claim 14, The organic material is pentacene, tetracene, tetratracene, anthracene, naphthalene, alpha-6-thiophene, alpha-4-thiophene, perylene and its derivatives, ru Rubrene and its derivatives, coronene and its derivatives, perylene tetracarboxylic diimide and its derivatives, perylene tetracarboxylic dianhydride and its derivatives Derivatives, oligoacenes and derivatives thereof of naphthalene, oligothiophenes and derivatives thereof of alpha-5-thiophene, phthalocyanine and derivatives thereof with or without metal, pyromellitic dianhydrides and derivatives thereof, A method of manufacturing a flat panel display device comprising at least one of pyromellitic diimide and derivatives thereof. The method of claim 14, And the inorganic material includes at least one of CdS, GaS, ZnS, CdSe, CaSe, ZnSe, CdTe, SiC, and Si. The method according to any one of claims 11 to 13, The forming of the semiconductor layer may include applying an amorphous silicon layer and crystallizing the amorphous silicon layer into a polycrystalline silicon layer. The method according to any one of claims 11 to 13, The substrate is a method of manufacturing a flat panel display device, characterized in that the glass substrate. A flat panel display manufactured according to any one of claims 11 to 13.

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