KR20110070599A - Method for manufacturing of thin film transistor - Google Patents

Abstract

PURPOSE: A method for manufacturing a thin film transistor and a flat display is provided to prevent a process failure and improve the performance of a device by crystallizing a channel layer using infrared laser. CONSTITUTION: A gate electrode(11) is formed a substrate(10). A gate insulation layer(12), an amorphous silicon layer(14), and a first insulation layer(17) are successively formed on the gate electrode. The amorphous silicon layer on the upper side of the gate electrode is crystallized by scanning laser(200) from one side to the other side of the substrate. An etch stop pattern is formed on the upper side of the gate electrode by performing a mask process on the substrate which is crystallized. A doped amorphous silicon layer and a source/drain metal layer are successively formed on the substrate with the etch stop pattern.

Description

Method for manufacturing thin film transistor and flat panel display device {Method for manufacturing of Thin Film Transistor}

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

Recently, a flat panel display device, which has been spotlighted as an advanced display device, for example, an active matrix liquid crystal display (AMLCD), an electron emission display device (FED), or an organic light emitting display device In the organic light emitting diode display (OLED), a thin film transistor (TFT) is used to drive each pixel.

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

In addition, a single crystal silicon substrate, a quartz substrate, a glass substrate, or a plastic substrate may be used as the substrate used in the flat panel display device. However, glass substrates are widely used because of the low cost, transparency, and ease of manufacture.

However, in order to change the silicon in the amorphous state formed on the glass substrate into the crystalline silicon, the crystallization heat treatment must be performed in a temperature range where the glass substrate is not deformed.

As such, a low temperature polysilicon (LTPS) technique for producing polycrystalline silicon at low temperature includes 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, the laser annealing method mainly uses an excimer laser having a wavelength of 308 nm.

Since the laser annealing method using such an excimer laser has a high absorption rate in amorphous silicon, there is an advantage that polysilicon may be manufactured by heating and melting amorphous silicon within a short time without damaging the substrate.

However, the laser annealing method using an excimer laser has low electron mobility of the manufactured polycrystalline silicon, and it is difficult to secure uniformity of the entire thin film transistor. Therefore, a polysilicon thin film transistor (Poly-Silicon Thin Film) is used for high quality flat panel display devices. There is a limit to manufacturing a transistor.

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

The present invention provides a method for fabricating a thin film transistor and a flat panel display device by using an infrared ray laser to crystallize the channel layer of the thin film transistor to improve device performance and prevent process defects.

In addition, the present invention provides a method of manufacturing a thin film transistor and a flat panel display device which have undergone a direct infrared laser crystallization process using a gate electrode to form a channel layer of the thin film transistor without using a separate thermal conductive film.

The thin film transistor manufacturing method of the present invention for solving the above problems comprises the steps of forming a gate electrode on a substrate, and sequentially forming a gate insulating film, an amorphous silicon film and a first insulating film on the gate electrode; Irradiating a laser beam on the resulting product to locally crystallize an amorphous silicon film on the gate electrode; Forming a etch stop pattern on the gate electrode by performing a mask process on the substrate on which the crystallization process is completed; And sequentially forming a doped amorphous silicon film and a source / drain metal film on the substrate on which the etch stop pattern is formed, and then forming a channel layer including a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film according to a mask process. Forming a step.

In addition, the method of manufacturing a flat panel display of the present invention may include forming a gate electrode on a substrate, and sequentially forming a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Irradiating a laser beam on the resulting product to locally crystallize an amorphous silicon film on the gate electrode; Forming a etch stop 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 formed on the substrate on which the etch stop pattern is formed, and then a channel layer including a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film is formed according to a mask process. Doing; Forming a second insulating film on the substrate on which the source / drain electrodes are formed, and then forming a contact hole exposing a portion 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 a pixel electrode.

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

In addition, the method of manufacturing the thin film transistor of the present invention has a simple effect because the infrared laser crystallization process is performed using a gate electrode without a separate thermal conductive film forming process to crystallize the channel layer.

In addition, the method of manufacturing the thin film transistor of the present invention uses a gate electrode formed on the substrate to crystallize the channel layer on the gate electrode, so that there is no effect of a separate laser alignment process for channel layer crystallization.

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 numbers refer to like elements throughout.

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

Referring to FIG. 1, a metal film is formed on a substrate 10, followed by an exposure and development process according to a mask process, followed by an etching process 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 must convert the energy irradiated into heat using an infrared diode laser having a wavelength of 800 to 810 nm, Mo, MoTi. Cr and the like can be used. Alternatively, in order to prevent oxidation by heat, it may be formed in the form of a metal film double film having excellent oxidation resistance. That is, it can be formed of Ti / Mo, Oxide / Mo, Cr / Mo and the like.

As described above, when the gate electrode 11 is formed on the substrate 10, as shown in FIG. 2A, 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 of the upper portion of the substrate 10 to the other side to crystallize the amorphous silicon layer 14 on the upper portion of the gate electrode 10. The laser 200 preferably uses an infrared ray diode laser (IR diode laser). However, in some cases, an excimer laser may be used.

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

2B is a plan view illustrating a state in which the laser 200 scans an upper portion of the substrate 10 to crystallize the amorphous silicon film 14. The laser 200 scans the entire surface of the substrate 10, but when the laser beam is irradiated to the gate electrode 11 formed on the substrate 10, heat is generated in the gate electrode 11, and the gate electrode ( 11, the amorphous silicon film 14 on the gate electrode 11 is crystallized by the heat generated in the gate electrode 11.

That is, the laser beam is irradiated to the entire region of the substrate 10, but the region to be crystallized is a partial region of the amorphous silicon film 14 corresponding to the gate electrode 11. Therefore, the present invention does not require a separate laser 200 alignment process to crystallize the gate electrode 11. This is because the crystallization is performed only on the gate electrode 11 by self aligning only by the laser scanning process.

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

Next, as shown in FIG. 4, a mask process is performed to etch the first insulating layer 17 on 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 shown in FIGS. 5 and 6, ohmic made of amorphous silicon doped (n + or p +) in the entire region of the substrate 10. The contact layer 20 and the source / drain metal film 28 are sequentially formed.

As described above, when the source / drain metal layer 28 is formed on the substrate 10, as shown in FIG. 7, the photoresist is formed on the substrate 10 and subjected to an exposure and development process to form a photoresist pattern. Form 100. Next, the source / drain metal layer 28, the ohmic contact layer 20, and the polysilicon layer 24 are etched using the photoresist pattern 100 as a mask, and the source / drain electrodes 32a and 32b and The polysilicon film 24 serving as the ohmic contact layer 20 and the channel layer is patterned.

As described above, when the thin film transistor is formed by forming the source / drain electrodes 32a and 32b, an ashing process is performed as shown in FIG. 8 to remove the photoresist pattern 100.

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

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

As described above, when the contact hole process is completed, as shown in FIG. 10, a transparent conductive material is formed on the entire area of the substrate 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 thin film transistor and a method of manufacturing a flat panel display device having the same according to the present invention.

 (Explanation of reference numerals for the main parts of the drawings)

10: substrate 11: gate electrode

12: gate insulating film 14: amorphous silicon film

32a, 32b: source / drain electrodes 17a: etch stop pattern

200: laser

Claims (6)

Forming a gate electrode on the substrate, Sequentially forming a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Irradiating a laser beam on the resulting product to locally crystallize an amorphous silicon film on the gate electrode; Forming a etch stop 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 formed on the substrate on which the etch stop pattern is formed, and then a channel layer including a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film is formed according to a mask process. Thin film transistor manufacturing method comprising the step of. The method of claim 1, wherein the gate electrode is Mo, MoTi. Cr, Ti / Mo, Oxide / Mo, Cr / Mo, W, MoW manufacturing method of a thin film transistor, characterized in that using one of. The method of claim 1, wherein locally crystallizing the amorphous silicon film, And the crystallization is performed only on the region of the amorphous silicon film corresponding to the gate electrode when the laser is scanned on the substrate. The method of claim 1, wherein the laser annealing process using the infrared diode laser And irradiating the infrared diode laser to the heat transfer film, the irradiated energy is converted into heat in the heat transfer film, and the heat is transferred to an amorphous silicon film to crystallize the thin film transistor. The method of claim 1, wherein the impurity amorphous silicon film has a thickness. Method for producing a polysilicon thin film transistor, characterized in that formed in 50 ~ 200Å. Forming a gate electrode on the substrate, Sequentially forming a gate insulating film, an amorphous silicon film, and a first insulating film on the gate electrode; Irradiating a laser beam on the resulting product to locally crystallize an amorphous silicon film on the gate electrode; Forming a etch stop 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 formed on the substrate on which the etch stop pattern is formed, and then a channel layer including a source / drain electrode, an ohmic contact layer, and a crystallized amorphous silicon film is formed according to a mask process. Doing; Forming a second insulating film on the substrate on which the source / drain electrodes are formed, and then forming a contact hole exposing a portion of the drain electrode; And And forming a pixel electrode by etching a transparent conductive material on the second insulating layer on which the contact hole is formed.

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