KR101686242B1 - Method for manufacturing of Thin Film Transistor - Google Patents

Abstract

The present invention discloses a method of manufacturing a thin film transistor and a flat panel display device. A method of manufacturing a thin film transistor according to the present invention includes the steps of disposing a gate electrode on a substrate, sequentially arranging a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode, and forming an infrared diode laser A step of locally crystallizing the amorphous silicon film over the gate electrode by irradiating a laser beam using a laser beam; a step of performing a masking process on the substrate on which the crystallization process has been completed to arrange an etching prevention pattern on the gate electrode; Sequentially arranging a doped amorphous silicon film and a source / drain metal film on a substrate, and then disposing a channel layer made of a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film according to a mask process.

The thin film transistor manufacturing method of the present invention has an effect of improving device performance and preventing process defects by crystallizing a channel layer by using an infrared ray laser.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a thin film transistor (TFT)

The present invention relates to a method of manufacturing a thin film transistor.

2. Description of the Related Art In recent years, a flat panel display device that has been popular as a high-tech display device, such as an active matrix liquid crystal display (AMLCD), an electron emission display device (FED) (OLED), a thin film transistor (TFT) is used to drive each pixel.

Such a TFT is mainly manufactured using silicon. When silicon is manufactured in a polycrystalline state rather than an amorphous state, the field effect mobility is high, so that the flat panel display can be driven at a high speed.

A single crystal silicon substrate, a quartz substrate, a glass substrate, a plastic substrate, or the like can be used as the substrate used for the flat panel display, but glass substrates are widely used because they are inexpensive, transparent and easy to manufacture.

However, in order to convert the amorphous silicon formed on the glass substrate into crystalline silicon, the crystallization heat treatment must proceed in a temperature range in which the glass substrate is not deformed.

Thus, a low temperature polysilicon (LTPS) technique for producing polycrystalline silicon at a low temperature is a laser annealing method. Laser annealing methods are known to be superior to other low temperature crystallization techniques because of their low manufacturing cost and high efficiency.

Generally, in the laser annealing method, an excimer laser having a wavelength of 308 nm is mainly used.

The laser annealing method using the excimer laser has an advantage that the polysilicon can be manufactured by heating and melting the amorphous silicon within a short time without damaging the substrate because the laser wavelength used has a high absorption rate in the amorphous silicon.

However, since the laser annealing method using the excimer laser has a low electron mobility of the produced polycrystalline silicon and it is difficult to ensure the uniformity of the entire thin film transistor, a polysilicon thin film transistor There is a limit in manufacturing a transistor.

Therefore, a method of manufacturing a polysilicon thin film transistor capable of realizing high mobility and uniformity is required.

The present invention provides a method of manufacturing a thin film transistor and a flat panel display in which an infrared ray laser is used to crystallize a channel layer of a thin film transistor to improve device performance and prevent a process failure.

The present invention also provides a method of manufacturing a thin film transistor and a flat panel display in which a direct infrared laser crystallization process is performed using a gate electrode without forming a separate thermal conductive film to crystallize a channel layer of the thin film transistor.

According to an aspect of the present invention, there is provided a method of manufacturing a thin film transistor including: forming a gate electrode on a substrate; sequentially forming a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Locally crystallizing the amorphous silicon film over the gate electrode by irradiating a laser beam on the resultant product; Performing a masking process on the substrate on which the crystallization process is completed to form an etching prevention pattern on the gate electrode; And a source / drain metal layer are sequentially formed on the substrate having the etch stop pattern formed thereon, and a channel layer made of a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon layer is formed by a mask process .

According to another aspect of the present invention, there is provided a method of manufacturing a flat panel display, including: forming a gate electrode on a substrate; sequentially forming a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Locally crystallizing the amorphous silicon film over the gate electrode by irradiating a laser beam on the resultant product; Performing a masking process on the substrate on which the crystallization process is completed to form an etching prevention pattern on the gate electrode; A doped amorphous silicon film and a source / drain metal film are sequentially formed on the substrate having the etch stopping pattern formed thereon, and then a channel layer made of a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film is formed ; Forming a second insulating layer on the substrate on which the source / drain electrode is formed, and then forming a contact hole exposing a part of the drain electrode; And forming a transparent conductive material on the second insulating layer on which the contact hole is formed, followed by etching to form the pixel electrode.

The thin film transistor manufacturing method of the present invention has an effect of improving device performance and preventing process defects by crystallizing a channel layer by using an infrared ray laser.

In addition, in the method of manufacturing a thin film transistor of the present invention, a direct infrared laser crystallization process is performed using a gate electrode without crystallizing the channel layer to form a separate thermal conductive film, thereby simplifying the process.

In addition, since the channel layer above the gate electrode is crystallized by using the gate electrode formed on the substrate, the method of manufacturing the thin film transistor of the present invention does not require a separate laser alignment process for crystallizing the channel layer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 to 10 illustrate a method of manufacturing a thin film transistor and a flat panel display device having the thin film transistor according to the present invention.

Referring to FIG. 1, a metal film is formed on a substrate 10, an exposure and development process is performed according to a mask process, and an etching process is performed to form a gate electrode 11. Since the gate electrode 11 serves as a heat transition layer for crystallizing the amorphous silicon film 14, a metal having excellent thermal conductivity is used.

Therefore, since the gate electrode 11 is required to convert the irradiated energy into heat by using an infrared diode laser having a wavelength of 800 to 810 nm, Mo, MoTi. Cr and the like can be used. Alternatively, it can be formed in the form of a metal film having excellent oxidation resistance in order to prevent oxidation by heat. That is, it can be formed of Ti / Mo, Oxide / Mo, Cr / Mo, or the like.

2A, when the gate electrode 11 is formed on the substrate 10, the gate insulating film 12, the amorphous silicon film 14, and the first insulating film 17 are sequentially formed do. Then, the laser 200 is scanned from one side to the other side of the substrate 10 to crystallize the amorphous silicon film 14 on the gate electrode 11. The laser 200 preferably uses an infrared diode laser (IR diode laser), but in some cases, an excimer laser can be used.

When the laser beam irradiated by the laser 200 touches the gate electrode 11, heat is generated, and this heat is transferred to the amorphous silicon film 14. As described above, when the amorphous silicon film 14 is indirectly crystallized by thermal conduction without directly irradiating the amorphous silicon film 14 with a laser beam, solid-state crystallization is possible, and uniform device characteristics can be obtained.

FIG. 2B is a plan view showing a state in which the laser 200 scans the upper surface of the substrate 10 to crystallize the amorphous silicon film 14. FIG. The laser 200 scans the entire surface of the substrate 10. When the laser beam is irradiated on the gate electrode 11 formed on the substrate 10, heat is generated in the gate electrode 11, 11, the amorphous silicon film 14 above the gate electrode 11 is crystallized.

That is, the laser beam is irradiated to the entire region of the substrate 10, but the crystallized region is a portion of the amorphous silicon film 14 corresponding to the gate electrode 11. Therefore, in the present invention, there is no need to perform a separate laser 200 alignment process to crystallize the upper portion of the gate electrode 11. [ Self alignment is performed only by the laser scanning process and crystallization is performed only on the upper portion of the gate electrode 11.

As described above, when the laser scanning process is completed, the amorphous silicon film formed on the substrate 10 is formed with the polysilicon film 24 locally crystallized only on the gate electrode 11.

Then, as shown in FIG. 4, a mask process is performed to etch the first insulating layer 17 above the gate electrode 11 to form an etch stopper 17a.

As described above, when the etch stop pattern 17a is formed on the substrate 10 as described above, it is possible to form the etch stop pattern 17a on the entire surface of the substrate 10 by using the ohmic (n + The contact layer 20 and the source / drain metal film 28 are sequentially formed.

7, when a source / drain metal film 28 is formed on the substrate 10, a photoresist is formed on the substrate 10, and exposure and development processes are performed to form a photoresist pattern (100). Then, the source / drain electrodes 32a, 32b, and 32c are formed by etching the source / drain metal film 28, the ohmic contact layer 20, and the polysilicon film 24 using the photoresist pattern 100 as a mask, The ohmic contact layer 20 and the polysilicon film 24 serving as a channel layer are patterned.

After the source / drain electrodes 32a and 32b are formed and the thin film transistor is completed, an ashing process is performed to remove the photoresist pattern 100 as shown in FIG.

Then, a second insulating film 40 is formed on the substrate 10 on which the thin film transistor is formed, and a contact hole process is performed to expose a part of the drain electrode 32b by a mask process.

A contact hole 50 from which the second insulating film 40 is removed is formed on the drain electrode 32b.

After the contact hole process is completed, a transparent conductive material is formed on the entire region of the substrate 10 as shown in FIG. 10, and then a mask process is performed to electrically contact the drain electrode 32b The pixel electrode 60 is formed.

1 to 10 illustrate a method of manufacturing a thin film transistor and a flat panel display device having the thin film transistor according to the present invention.
(Description of Reference Numbers to Main Parts of the Drawings)

delete

10: substrate 11: gate electrode

12: gate insulating film 14: amorphous silicon film

32a, 32b: source / drain electrode 17a: etching prevention pattern

200: laser

Claims (10)

Disposing a gate electrode on the substrate; Sequentially arranging a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Locally crystallizing the amorphous silicon film over the gate electrode by irradiating a laser beam using an infrared diode laser onto the substrate on which the result is disposed; Depositing an etching prevention pattern on the gate electrode by performing a mask process on the substrate on which the crystallization process is completed; And A doped amorphous silicon film and a source / drain metal film are sequentially disposed on the substrate on which the etch stop pattern is disposed, and then a channel layer made of a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film is formed Comprising the steps of: The step of locally crystallizing the amorphous silicon film The energy of the laser beam irradiated on the substrate is converted into heat in the gate electrode and the converted heat is transferred to the amorphous silicon film above the gate electrode to cause crystallization in the region of the upper amorphous silicon film corresponding to the gate electrode Wherein the thin film transistor is formed on the substrate. The semiconductor device according to claim 1, wherein the gate electrode is made of Mo, MoTi. Cr, Ti / Mo, Oxide / Mo, Cr / Mo, W and MoW. delete delete The method according to claim 1, Wherein the infrared diode laser irradiates an infrared beam having a wavelength of 800 nm or more and 810 nm or less. Sequentially arranging a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Locally crystallizing the amorphous silicon film on the gate electrode by irradiating a laser beam using an infrared diode laser on the substrate on which the resultant is disposed; Depositing an etching prevention pattern on the gate electrode by performing a mask process on the substrate on which the crystallization process is completed; A doped amorphous silicon film and a source / drain metal film are sequentially disposed on the substrate on which the etch stop pattern is disposed, and then a channel layer made of a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film is formed Placing; Disposing a second insulating film on the substrate on which the source / drain electrodes are disposed, and disposing a contact hole exposing a part of the drain electrode; And Disposing a transparent conductive material on the second insulating film on which the contact hole is disposed, and disposing the pixel electrode by etching, The step of locally crystallizing the amorphous silicon film Wherein the energy of the laser beam irradiated on the substrate is converted into heat in the gate electrode and the heat is transferred to the amorphous silicon film on the gate electrode to crystallize the region of the upper amorphous silicon film corresponding to the gate electrode, Type display device. The method according to claim 6, wherein the gate electrode is made of Mo, MoTi. Cr, Ti / Mo, Oxide / Mo, Cr / Mo, W and MoW. delete delete The method according to claim 6, Wherein the infrared diode laser irradiates an infrared beam having a wavelength of 800 nm or more and 810 nm or less.

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