KR100348284B1 - thin film transistor and method for fabricating the same - Google Patents

Abstract

A thin film transistor and a method of manufacturing the same for providing a reliable and inexpensive display, comprising: a cradle formed through an etching process on a flexible substrate, a gate electrode formed under the cradle, an insulating film formed on a substrate including the gate electrode, An active layer formed on the insulating layer deposited on the gate electrode, a doped silicon layer formed on the edge of the insulating layer over the active layer and the gate electrode so that the center of the surface of the active layer is exposed, and a source and a drain formed on the doped silicon layer A thin film transistor including an electrode, a metal connected to a source and a drain electrode, and a dielectric material to planarize a substrate. Therefore, by using the thin film transistor according to the present invention, it is possible to manufacture a thin film transistor-liquid crystal display (LCD) or other display which is excellent in processing and reliability and is safe to roll around. In addition, because the low temperature process is used, the manufacturing cost is low and many people can provide a low-cost and convenient display.

Description

Thin film transistor and method for fabricating the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor devices, and more particularly to a thin film transistor and a method of manufacturing the same.

Generally, thin film transistors (TFTs) are used in place of CMOS load transistors or load resistors in SRAM cells of 4M or 10M or more.

In addition, it is widely used as a switching device for switching the image data signal of each pixel area in the liquid crystal display device.

Thin film transistors made on conventional plastic substrates are designed or made to protrude on plastic plates at high temperatures.

However, the above-described thin film transistor according to the related art and a manufacturing method thereof have the following problems.

Conventional thin film transistors are made or designed in the form of protrusions on plastic plates, so the thin film transistors are easily damaged due to their inherent properties of plastic, which are well bent at high temperatures.

For example, when a scroll is made using a conventional thin film transistor technology, the thin film transistor will be pressed or immediately damaged if the display is rolled out.

Therefore, the present invention is to solve the above problems, by making a cradle (cradled) structure on the flexible film (flexible film) by manufacturing a thin film transistor at a low temperature in the cradle, a thin film transistor-liquid crystal display (LCD) or other When applied to a display, it is an object to provide a good and cheap thin film transistor and a method of manufacturing the safe to roll around.

1 is a structural cross-sectional view of a thin film transistor according to the present invention.

2 is a process plan view of a thin film transistor according to the present invention;

3A to 3L are cross-sectional views and a process perspective view showing a manufacturing process of a thin film transistor according to the present invention.

Explanation of symbols for main parts of the drawings

1 flexible substrate 12,13 doped silicon layer

2,3 photoresist 14 drain electrode

4: cradle 15: source electrode

5 gate electrode 16 metal connected to drain metal

6 insulating film 17 metal connected to source metal

7,8 photoresist pattern 18 dielectric material

10: active layer or amorphous silicon 9, 11: amorphous silicon

A thin film transistor according to the present invention for achieving the above object is a cradle formed on a flexible substrate, a gate electrode formed under the cradle, an insulating film formed on the substrate including the gate electrode, and an insulating film deposited on the gate electrode An active layer formed on the active layer, a doped silicon layer formed on the edge of the insulating layer above the active layer and the gate electrode to expose the center of the active layer surface, a source and drain electrode formed on the doped silicon layer, a metal connected to the source and drain electrode, And a dielectric material to planarize the substrate.

The thin film transistor manufacturing method of the present invention configured as described above comprises a process of forming a cradle by etching a flexible substrate, a process of forming a gate electrode under the cradle, a process of forming an insulating film on a substrate including the gate electrode, and a gate Forming an active layer on the insulating film above the electrode, separating the doped silicon layer on the corner of the insulating layer above the gate and the active layer so that the center of the surface of the active layer is exposed, and forming a source and a drain electrode on the doped silicon layer. And forming a metal, connecting a metal to the source and drain electrodes, and planarizing the substrate using a dielectric material.

According to the present invention, a thin film transistor having excellent processing and reliability can be obtained by making a cradle structure on a flexible substrate and manufacturing a thin film transistor in the cradle. Thus, using the thin film transistor according to the present invention, it is possible to manufacture a thin film transistor-liquid crystal display (LCD) or other display that is safe to carry around. In addition, because the low temperature process is used, the manufacturing cost is low and many people can provide a low-cost and convenient display.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

A preferred embodiment of a thin film transistor and a method of manufacturing the same according to the present invention will be described with reference to the accompanying drawings.

1 is a structural cross-sectional view of a thin film transistor according to the present invention, and FIG. 2 is a structural plan view of the thin film transistor according to the present invention.

First, as shown in FIG. 1, in the thin film transistor according to the present invention, a cradle is formed on a flexible acrylate copolymer film 1, a gate electrode 5 is formed below the cradle, An insulating film 6 made of a dielectric material such as SiN or SiO ₂ is formed on the entire surface of the substrate 1 including the gate electrode. Then, an active layer 10 made of amorphous silicon is formed on the insulating film 6 above the gate electrode 5, and the insulating layer over the active layer 10 and the gate electrode 5 is exposed so that the active layer 10 is exposed. The n-type or p-type doped silicon layers 12 and 13 are separated and formed on the edges, and the source 15 and drain 14 electrodes are formed on the doped silicon layers 12 and 13. A dielectric material is formed to widen the drain to the source 15 and drain 14 electrodes, to connect metals 16 and 17 connecting the source electrode to the wall around the cradle, and to planarize the substrate 1. 18 is formed.

2 is a plan view of the thin film transistor according to the present invention as viewed from above.

As shown in FIG. 2, it is seen that the metal 17 connected to the source electrode 15 intersects with the gate electrode 5. However, there is an insulating film 6 which is used for passivation for proper treatment between the surface of the semiconductor device and the junction of the metal 17 and the gate electrode 5, and for blocking harmful environment to stabilize the device characteristics. No short circuit occurs.

Referring to the thin film transistor manufacturing method of the present invention configured as described above is as follows.

3A to 3L are process cross-sectional views of a thin film transistor according to the present invention.

As shown in FIG. 3A, photoresist 2,3 is formed around the predetermined area on the flexible substrate 1 using exposure and development processes.

As shown in FIG. 3B, the cradle 4 is formed by etching the flexible substrate 1 using the photoresists 2 and 3 as masks.

Here, the etching may use a variety of methods, such as reactive ion etching (RIE), sputtering, wet etching (wet etching), the depth of the cradle (4) may vary, but about 5000Å is suitable.

As shown in FIG. 3C, the photoresist 2, 3 on the flexible substrate 1 on which the cradle 4 is formed is removed, and a pattern for forming the gate electrode 5 is formed. Thereafter, the gate electrode 5 is formed by etching to selectively remove the gate electrode material.

Here, Ti / Au is used as the material of the gate electrode 5. In addition, the type and configuration of the metal may be changed depending on the use, and indium tin oxide (ITO) metal may be used. An evaporator is used as the deposition equipment for the gate electrode 5, and various other equipments may be used.

3D is a process perspective view showing three-dimensional thin film transistor manufacturing process up to now.

As shown in FIG. 3D, the state in which the cradle 4 is formed by etching the flexible substrate 1, the state of the gate electrode 5 formed under the cradle 4, the position of the gate electrode 5, and the like are seen. Can be.

As shown in FIG. 3D, the gate electrode 5 is pulled out long over the wall around the cradle, and at the same time a metal line is made to receive an electrical signal.

As shown in Fig. 3E, an insulating film 6 for insulating the gate electrode 5 from the source electrode 15 and the drain electrode 14 to be made continuously is deposited.

Here, the material used as the insulating film 6 is SiN, and the gas combination and insulating film of SiH ₄ : NH ₃ : N ₂ = 10sccm: 40sccm: 100sccm at about 110 ° C. using a PECVD (Plasma Enhanced Chemical Vapor Deposition) device. (6) SiN can be deposited under various conditions such as the deposition pressure under the condition of about 300mTorr, the gas combination of the above conditions, or the pressure during deposition. It is also possible to use other dielectric materials, such as SiO ₂ , in addition to SiN, and in the case of deposition equipment, PRCVD, ECR-CVD, sputter equipment, etc. may be used in addition to the PECVD used herein.

Subsequently, as shown in FIG. 3F, a photoresist for the portion on which the active layer of the insulating film 6 is to be deposited is formed, and the photoresist on the insulating film above the gate is removed to form the photoresist patterns 7 and 8. Here, overhangs were made in the photoresist patterns 7 and 8.

As shown in FIG. 3G, amorphous silicon (9, 10, 11) is formed using photoresist patterns (7, 8) as a mask at a low temperature. A portion of amorphous silicon 9, 11 is then deposited over photoresist 7, 8, and another portion 10 is deposited on top insulating film 6 of gate electrode 5.

Here, the material used as amorphous silicon (9,10,11) is SiN, and at about 110 ° C. or less, SiH ₄ : H ₂ = 10-30 sccm: 10-300 sccm in combination with amorphous silicon deposition The pressure is deposited under the condition of about 100-900 mTorr. In addition to H ₂ used as a carrier gas, various gases such as Ar may be used. The gas combination and gas flow rate under the above conditions may be changed.

As shown in FIG. 3H, when the photoresist patterns 7 and 8 are removed, the amorphous silicon 9 and 11 deposited on the photoresist 7 and 8 are simultaneously removed, and the amorphous silicon on the gate side insulating film ( Only 10) remains to form the active layer 10.

As shown in FIG. 3I, the doped silicon layers 12 and 13 are separated and formed on the edges of the insulating layer over the active layer and the gate electrode so that the center of the active layer 10 is exposed.

Here, the doped silicon layer is formed using phosphorus (P) for n-type and boron (B) for p-type. The equipment used to form the doped silicon layer is PECVD, but other equipment may be used.

As shown in FIG. 3J, the source 15 and drain 14 electrodes are formed on the doped silicon layers 12, 13.

Here, although the metal used for the drain 14 and the source 15 is Ti / Au, you may change it to another metal depending on a use.

As shown in FIG. 3K, the metal 16 is connected to the drain electrode 14 to widen the drain, and the metal 17 is connected to the source electrode 15 to connect the source metal over the wall around the cradle. Pulled out.

Here, the metal used is an ITO metal, but other metals may be used depending on the use.

As shown in FIG. 3L, the thin film transistor made above is protected and the substrate 1 is planarized with a dielectric material 18 for rubbing.

Here, the material used for planarization of the substrate is a polyimide having a high curing temperature in order to improve stability, but other dielectric materials may be used.

Through the above process, the thin film transistor manufacturing process of the present invention is completed.

As described above, the thin film transistor and the manufacturing method thereof according to the present invention have the following effects.

By making a cradle structure on a flexible substrate and manufacturing a thin film transistor in the cradle, it is possible to overcome the disadvantage that the device easily breaks when the flexible film is used as a substrate, and to obtain a thin film transistor having excellent processing and reliability. .

Thus, using the thin film transistor according to the present invention, it is possible to manufacture a thin film transistor-liquid crystal display (LCD) or other display that is safe to carry around.

In addition, since the low-temperature process is used, the manufacturing cost is low and there is an effect that can provide a low-cost convenient display to many people.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (7)

With flexible substrates, A cradle formed on the flexible substrate, A gate electrode formed under the cradle; An insulating film formed on the flexible substrate including the gate electrode; An active layer formed on the insulating film deposited on the gate electrode; A doped silicon layer formed on the corners of the insulating layer over the active layer and the gate electrode so that the center of the surface of the active layer is exposed; Source and drain electrodes formed on the doped silicon layer; A metal connected to the source and drain electrodes; And a dielectric material to planarize the substrate. The method of claim 1, The flexible substrate is a thin film transistor, characterized in that using a flexible acrylic copolymer substrate. The method of claim 1, And the active layer is made of amorphous silicon. Etching the flexible substrate to form a cradle; Forming a gate electrode under the cradle; Forming an insulating film on the flexible substrate including the gate electrode; Forming an active layer on the insulating film over the gate electrode; Separating and forming a doped silicon layer on an edge of an insulating layer above the active layer and the gate electrode so that the center of the surface of the active layer is exposed; Forming a source and a drain electrode on the doped silicon layer; Coupling a metal to the source and drain electrodes; And planarizing the substrate using a dielectric material. The method of claim 4, wherein The method of forming the cradle, Forming a photoresist around a region on the flexible substrate; Etching the flexible substrate using the photoresist as a mask; And removing the photoresist. The thin film transistor of claim 4, wherein the insulating layer and the active layer are formed at a temperature of 110 ° C. or less. The method of claim 4, wherein And the metal connected to the gate electrode and the source electrode is formed to extend over the wall of the cradle.