KR20110024697A - Manufacturing method of thin film transistor - Google Patents

Abstract

PURPOSE: A method for manufacturing a thin film transistor is provided to increase a contact area among a semiconductor layer, a source electrode, and a drain electrode, thereby increasing an electrical property of the thin film transistor. CONSTITUTION: A gate electrode(110) is formed on a substrate(100). An insulating film(120) is formed on the gate electrode. A semiconductor layer(130) with oxide is formed on the insulating film. A source electrode(140a) and a drain electrode(140b) are electrically connected to the semiconductor layer. Laser is irradiated on the source electrode and the drain electrode to form an ohmic layer on the semiconductor layer.

Description

Manufacturing Method Of Thin Film Transistor

The present invention relates to a method for manufacturing a thin film transistor, and more particularly, to a method for manufacturing a thin film transistor capable of improving ohmic characteristics between a semiconductor layer, a source electrode, and a drain electrode.

In general, thin film transistors are not only the characteristics of basic thin film transistors such as mobility, leakage current, etc., but also durability and electrical reliability for maintaining a long life is very important. Here, the semiconductor layer of the thin film transistor is mainly formed of amorphous silicon or polycrystalline silicon, the amorphous silicon has the advantage that the film forming process is simple and the production cost is low, but the electrical reliability is not secured. In addition, polycrystalline silicon is very difficult to apply a large area due to the high process temperature, there is a problem that the uniformity according to the crystallization method is not secured.

On the other hand, when the semiconductor layer is formed of an oxide, it is possible to obtain high mobility even when the film is formed at a low temperature. Since the resistance change is large depending on the oxygen content, it is very easy to obtain the desired physical properties. It's attracting great attention. In particular, examples thereof include zinc oxide (ZnO), indium zinc oxide (InZnO), indium gallium zinc oxide (InGaZnO ₄ ), and the like.

Although oxide semiconductor thin film transistors have superior mobility and reliability characteristics than conventional amorphous silicon thin film transistors, there is a problem in that an ohmic layer is formed between the oxide semiconductor and the source electrode and the drain electrode. Therefore, the ohmic characteristics between the oxide semiconductor layer, the source electrode, and the drain electrode are not good, which causes a problem in that the output characteristics of the thin film transistor are deteriorated.

Accordingly, the present invention provides a method of manufacturing a thin film transistor capable of improving ohmic characteristics between a semiconductor layer, a source electrode, and a drain electrode.

In order to achieve the above object, a method of manufacturing a thin film transistor according to an embodiment of the present invention comprises the steps of forming a gate electrode on a substrate, forming an insulating film on the gate electrode, comprising an oxide on the insulating film Forming a semiconductor layer, forming a source electrode and a drain electrode electrically connected to the semiconductor layer, and irradiating a laser to the source electrode and the drain electrode corresponding to the semiconductor layer to form an ohmic layer on the semiconductor layer. It may comprise the step of forming.

In addition, the method of manufacturing a thin film transistor according to an embodiment of the present invention includes forming a gate electrode on a substrate, forming an insulating film on the gate electrode, and forming a semiconductor layer including an oxide on the insulating film. Forming a metal layer on the semiconductor layer, irradiating a laser to the metal layer corresponding to the semiconductor layer to form an ohmic layer on the semiconductor layer, and removing the metal layer, and a source connected to the semiconductor layer. Forming an electrode and a drain electrode.

In addition, the method of manufacturing a thin film transistor according to an exemplary embodiment of the present invention includes forming a gate electrode on a substrate, forming an insulating film on the gate electrode, and forming a semiconductor layer including an oxide on the insulating film. The method may include forming an ohmic layer by irradiating a laser to the semiconductor layer, and forming a source electrode and a drain electrode electrically connected to the semiconductor layer.

The manufacturing method of the thin film transistor of the present invention has the advantage of improving the ohmic characteristics between the semiconductor layer, the source electrode and the drain electrode, thereby improving the characteristics of the thin film transistor.

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

1 is a cross-sectional view illustrating a thin film transistor according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a thin film transistor according to an exemplary embodiment of the present invention may include a substrate 100, a gate electrode 110 positioned on the substrate 100, and an insulating layer 120 that insulates the gate electrode 110. And a semiconductor layer 130 disposed on the insulating layer 120 and including an ohmic layer 135, and a source electrode 140a and a drain electrode 140b electrically connected to the semiconductor layer 130. can do.

The thin film transistor according to an exemplary embodiment of the present disclosure discloses a bottom gate type thin film transistor in which a gate electrode is disposed below, but any structure may be applied as long as the source electrode and the drain electrode are positioned above the semiconductor layer.

Hereinafter, a method of manufacturing a thin film transistor having a structure as shown in FIG. 1 will be described in detail with reference to FIGS. 2A to 6C.

2A to 3B are views illustrating a method of manufacturing a thin film transistor according to a first embodiment of the present invention, by process.

Referring to FIG. 2A, a metal film such as chromium (Cr), molybdenum (Mo), indium tin oxide (ITO), or aluminum (Al) is laminated on a substrate 200 including glass, plastic, or metal. do. Then, the gate electrode 210 is formed by patterning the photolithography process.

Here, the buffer layer may be further included between the substrate 200 and the gate electrode 210. The buffer layer is to prevent impurities such as ions from being diffused from the substrate 200 and contaminate subsequently formed devices. The buffer layer may be formed of an inorganic material such as silicon oxide or silicon nitride.

Next, an insulating film 220 is formed on the substrate 200 on which the gate electrode 210 is formed. The insulating film 220 may be a gate insulating film that electrically insulates the gate electrode 210, and may be formed of a silicon oxide film, a silicon nitride film, or a double layer thereof.

Next, referring to FIG. 2B, the semiconductor layer 230 is formed on the insulating film 220. Here, the semiconductor layer 230 may be formed of zinc tin oxide (ZnSnO) including zinc oxide (ZnO), and indium (In), gallium (Ga), or the like may be used to improve characteristics such as electrical conductivity. By doping, it may be formed so as to further contain indium zinc oxide (InZnO) or indium gallium zinc oxide (InGaZnO ₄ ).

Subsequently, the source electrode 240a and the drain electrode (eg, chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or an alloy thereof) are stacked to be electrically connected to both sides of the semiconductor layer 230. 240b).

Next, referring to FIG. 2C, a laser is irradiated to a region where the semiconductor layer 230, the source electrode 240a, and the drain electrode 240b overlap. Here, an IR diode laser can be used as the laser. IR diode lasers, also known as semiconductor lasers, are lasers that utilize the effect of emitting light when electrons and holes recombine over the energy gap when a large amount of excess carriers are injected into the diode due to the p-n junction.

When irradiating the source electrode 240a and the drain electrode 240b with an IR diode laser, the processing conditions of the IR diode laser include a wavelength range of about 800 to 850 nm, a power of 4 to 12 V, and a scan speed of 50 to 300 m / s. It can be carried out as.

Here, when an IR diode laser is irradiated to the source electrode 240a and the drain electrode 240a, the source electrode 240a and the drain electrode 240a made of metal act as a heat transfer medium so that the heat of the laser is applied to the semiconductor layer 230. Will be delivered.

The semiconductor layer 230 that receives heat from the source electrode 240a and the drain electrode 240b has a concentration of carriers in the semiconductor layer 230 at an interface region adjacent to the source electrode 240a and the drain electrode 240b. Increasingly, the ohmic layer 245 is formed.

The ohmic layer 245 may have an ohmic contact between the semiconductor layer 230, the source electrode 240a, and the drain electrode 240b, so that the characteristics of the thin film transistor may be improved.

3A and 3B illustrate another embodiment of the first embodiment of the present invention.

Referring to FIG. 3A, an insulating film 220 for forming a gate electrode 210 on a substrate 200 and insulating the gate electrode 210 on the gate electrode 210 under the same conditions as the above-described embodiment. Form. The semiconductor layer 230 including the oxide is formed on the insulating layer 220.

Next, the silicon oxide film or the silicon nitride film is laminated on the semiconductor layer 230 and then patterned to form an etch stopper 235. The etch stopper 235 serves to prevent the semiconductor layer from being damaged during the patterning process for forming the source electrode and the drain electrode later.

Next, referring to FIG. 3B, a semiconductor layer is formed by stacking chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or an alloy thereof on the substrate 200 on which the etch stopper 235 is formed. The source electrode 240a and the drain electrode 240b are formed to be electrically connected to both sides of the 230.

Thereafter, an IR diode laser is irradiated in the same manner as in the above-described embodiment to form an ohmic layer 245 to manufacture a thin film transistor.

As described above, in the method of manufacturing the thin film transistor according to the first embodiment of the present invention, the ohmic contact between the semiconductor layer and the source electrode and the drain electrode is formed by forming a ohmic layer on the semiconductor layer by the source electrode and the drain electrode acting as heat transfer medium. By implementing this there is an advantage that can improve the electrical characteristics of the thin film transistor.

4A to 4D are cross-sectional views illustrating processes of manufacturing a thin film transistor according to a second exemplary embodiment of the present invention.

Referring to FIG. 4A, a metal film such as chromium (Cr), molybdenum (Mo), indium tin oxide (ITO), or aluminum (Al) is stacked on the substrate 300. Then, the gate electrode 310 is formed by patterning it using a photolithography process.

Here, a buffer layer may be further included between the substrate 300 and the gate electrode 310. The buffer layer is to prevent impurities such as ions from being diffused from the substrate 300 and contaminate subsequently formed devices, and may be formed of an inorganic material such as silicon oxide or silicon nitride.

Next, an insulating film 320 is formed on the substrate 300 on which the gate electrode 310 is formed. The insulating layer 320 may be a gate insulating layer that electrically insulates the gate electrode 310, and may be formed of a silicon oxide layer, a silicon nitride layer, or a double layer thereof.

Next, the semiconductor layer 330 is formed on the insulating film 320. Here, the semiconductor layer 330 may be formed of zinc tin oxide (ZnSnO) including zinc oxide (ZnO), and in addition, doped with indium (In) or gallium (Ga) in order to improve characteristics such as electrical conductivity. As a result, indium zinc oxide (InZnO) or indium gallium zinc oxide (InGaZnO ₄ ) may be further included.

Next, the metal layer 335 is formed by depositing and patterning a metal material on the substrate 300 on which the semiconductor layer 330 is formed. Here, the metal layer 335 is patterned to be positioned on a region where the source electrode and the drain electrode are later contacted with the semiconductor layer 330. In addition, the metal layer 335 may be formed of chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or an alloy thereof.

4B, the ohmic layer 340 is formed by irradiating a laser to a region where the semiconductor layer 330 and the metal layer 335 overlap with each other. Here, an IR diode laser can be used as the laser. IR diode lasers, also known as semiconductor lasers, are lasers that utilize the effect of emitting light when electrons and holes recombine over the energy gap when a large amount of excess carriers are injected into the diode due to the p-n junction.

When irradiating an IR diode laser to the metal layer 335, the IR diode laser may be processed at a wavelength range of about 800 to 850 nm, a power of 4 to 12 V, and a scan speed of 50 to 300 m / s.

Here, when the IR diode laser is irradiated on the metal layer 335, the metal layer 335 made of metal acts as a heat transfer medium to transfer heat of the laser to the semiconductor layer 330.

Accordingly, in the semiconductor layer 330 that receives heat from the metal layer 335, the concentration of carriers in the semiconductor layer 330 increases in an interface region adjacent to the metal layer 335, thereby forming the ohmic layer 340.

The ohmic layer 340 may have an ohmic contact between the semiconductor layer 330 and a source electrode and a drain electrode to be formed later, thereby improving characteristics of the thin film transistor.

4C, the laser-irradiated metal layer 335 is etched and removed. Since the metal layer 335 irradiated with the laser may be lifted or damaged by the high temperature of the laser, the metal layer 335 is removed for future reliability.

Next, referring to FIG. 4D, chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), alloys thereof, and the like are stacked on both sides of the semiconductor layer 330. The source electrode 345a and the drain electrode 345b are formed to be electrically connected to the thin film transistor.

In the method of manufacturing the thin film transistor according to the second embodiment of the present invention, the ohmic layer is formed on the semiconductor layer using a metal as a heat transfer medium, thereby improving the ohmic characteristics between the source electrode and the drain electrode of the thin film transistor and the semiconductor layer. There is this. In addition, there is an advantage that the reliability of the thin film transistor may be improved by removing the metal irradiated with the laser and forming the source electrode and the drain electrode.

5A to 6C are cross-sectional views illustrating processes of manufacturing a thin film transistor according to a third exemplary embodiment of the present invention.

Referring to FIG. 5A, a metal film such as chromium (Cr), molybdenum (Mo), indium tin oxide (ITO), or aluminum (Al) is stacked on the substrate 400. The gate electrode 410 is then formed by patterning it using a photolithography process.

Here, the buffer layer may be further included between the substrate 400 and the gate electrode 410. The buffer layer is to prevent impurities such as ions from being diffused from the substrate 400 and contaminate subsequently formed devices. The buffer layer may be formed of an inorganic material such as silicon oxide or silicon nitride.

Next, an insulating film 420 is formed on the substrate 400 on which the gate electrode 410 is formed. The insulating film 420 may be a gate insulating film that electrically insulates the gate electrode 410, and may be formed of a silicon oxide film, a silicon nitride film, or a double layer thereof.

Next, referring to FIG. 5B, a semiconductor layer 430 is formed on the insulating film 420. Here, the semiconductor layer 430 may be formed of zinc tin oxide (ZnSnO) including zinc oxide (ZnO), and in addition, doped with indium (In) or gallium (Ga) to improve characteristics such as electrical conductivity. As a result, indium zinc oxide (InZnO) or indium gallium zinc oxide (InGaZnO ₄ ) may be further included.

The laser mask 440 is freely disposed on the substrate 400 including the semiconductor layer 430. The laser mask 440 is an opening and a blocking portion formed to allow the laser to pass therethrough, and may control an area to which the laser is irradiated through the opening. Here, the laser mask 440 is disposed by adjusting the position of the opening so that the laser is irradiated to a region where the semiconductor layer 430 is to come into contact with the source electrode and the drain electrode later.

Subsequently, the ohmic layer 450 is formed on the semiconductor layer 430 by irradiating a laser on the semiconductor layer 430. Here, a UV excimer laser can be used as a laser. UV excimer lasers are lasers that give electrical stimulation to an inert gas and emit wavelengths in the UV, or ultraviolet, region.

When irradiating the UV excimer laser to the semiconductor layer 430, the process conditions of the UV excimer laser may be performed for several seconds to several minutes at an energy density of 100 to 200mJ / ㎠. Here, when the energy density of the UV excimer laser is 100 mJ or more, the carrier concentration of the semiconductor layer 430 may be increased, and an ohmic layer may be formed. When 200 mJ or less, the semiconductor layer 430 may be prevented from being damaged. There is an advantage to that.

Here, when the UV excimer laser is irradiated to the semiconductor layer 430, carriers in the semiconductor layer 430 increase in concentration on the surface of the semiconductor layer 430 to which the laser is irradiated, thereby forming an ohmic layer 450.

The ohmic layer 450 may have an ohmic contact between the semiconductor layer 430 and a source electrode and a drain electrode formed later, thereby improving the characteristics of the thin film transistor.

Next, referring to FIG. 5C, chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or an alloy thereof may be stacked on the semiconductor layer 430 on which the ohmic layer 450 is formed. The source electrode 455a and the drain electrode 455b are formed to be electrically connected to both sides of the semiconductor layer 430.

In this case, the source electrode 455a and the drain electrode 455b are patterned to contact the ohmic layer 450, so that the semiconductor layer 430 and the source electrode 455a and the drain electrode 455b may form an ohmic contact. Form a transistor.

6A to 6C are diagrams illustrating another embodiment of the third embodiment of the present invention.

Referring to FIG. 6A, under the same conditions as in the above-described third embodiment, an insulating film 420 for forming a gate electrode 410 on the substrate 400 and insulating the gate electrode 410 on the gate electrode 410 is provided. ). The semiconductor layer 430 including the oxide is formed on the insulating film 420.

Next, a silicon oxide film or a silicon nitride film is stacked on the semiconductor layer 430 and then patterned to form an etch stopper 435. The etch stopper 435 serves to prevent the semiconductor layer from being damaged during the patterning process for forming the source electrode and the drain electrode later.

6B, the laser mask 440 is aligned and disposed on the substrate 400 on which the etch stopper 435 is formed, as in the above-described second embodiment, and then the laser is applied to the semiconductor layer 430. Irradiated to form an ohmic layer 450.

Next, referring to FIG. 6C, a source electrode (eg, chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or an alloy thereof) may be stacked and electrically connected to both sides of the semiconductor layer 430. 455a and the drain electrode 455b are formed. In this case, the source electrode 455a and the drain electrode 455b are patterned to contact the ohmic layer 450, so that the semiconductor layer 430 and the source electrode 455a and the drain electrode 455b may form an ohmic contact. Form a transistor.

As described above, in the method of manufacturing the thin film transistor according to the third embodiment of the present invention, unlike the first embodiment, the semiconductor layer and the source electrode are formed by directly irradiating a UV excimer laser to the semiconductor layer to form an ohmic layer. And by implementing an ohmic contact between the drain electrode there is an advantage that can improve the electrical characteristics of the thin film transistor.

Hereinafter, an experimental example comparing the characteristics of a thin film transistor manufactured according to an embodiment of the present invention, and a thin film transistor including a source electrode and a drain electrode as a single layer will be described. However, the following examples are merely to illustrate the present invention is not limited to the following experimental examples.

Experimental Example

Molybdenum (Mo) was sputter deposited on the substrate to form a 10 nm gate electrode, silicon nitride (SiNx) was PECVD deposited at 300 ° C. with a gate insulating film to form a 400 nm nitride film, and IGZO was stacked to a thickness of 500 kV semiconductor. A layer was formed. Then, molybdenum (Mo) was sputter deposited to form a source electrode and a drain electrode with a thickness of 2000 kPa. A thin film transistor was fabricated by irradiating an IR diode laser on a source electrode and a drain electrode at a wavelength of 800 nm, a power of 8 V, and a scan speed of 100 m / s.

Comparative Example

Under the same process conditions as in the experimental example described above, a thin film transistor was manufactured without a process of irradiating an IR diode laser.

Output characteristics of the thin film transistors manufactured according to the Experimental Example and Comparative Example were measured and shown in FIGS. 7A and 7B.

Looking at the output characteristics of the thin film transistor measuring the source-drain current according to the gate voltage with reference to Figures 7a and 7b, Figure 7a is an experimental example of the present invention that the source-drain current is continuously increased as the gate voltage is increased Although it can be seen that Figure 7b, a comparative example, it can be seen that the increase in source-drain current does not significantly reach the experimental example.

As described above, the method of manufacturing the thin film transistor according to the exemplary embodiment of the present invention may be formed to improve the contact area and contact characteristics between the semiconductor layer, the source electrode, and the drain electrode, thereby providing a thin film transistor having excellent electrical characteristics. There is an advantage.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

1 illustrates a thin film transistor according to an exemplary embodiment of the present invention.

2A to 3B are cross-sectional views of processes illustrating a method of manufacturing a thin film transistor according to a first embodiment of the present invention.

4A to 4D are cross-sectional views of processes illustrating a method of manufacturing a thin film transistor according to a second exemplary embodiment of the present invention.

5A to 6C are cross-sectional views illustrating a method of manufacturing a thin film transistor according to a third exemplary embodiment of the present invention.

7A and 7B are graphs illustrating output characteristics of thin film transistors manufactured according to Experimental and Comparative Examples of the present invention.

Claims (10)

Forming a gate electrode on the substrate; Forming an insulating film on the gate electrode; Forming a semiconductor layer including an oxide on the insulating film; Forming a source electrode and a drain electrode electrically connected to the semiconductor layer; And Irradiating a laser to the source electrode and the drain electrode corresponding to the semiconductor layer to form an ohmic layer in the semiconductor layer. The method of claim 1, The laser is a method of manufacturing a thin film transistor is an IR diode laser. The method of claim 1, The source electrode and the drain electrode are a heat transfer medium for transferring the heat of the laser to the semiconductor layer. The method of claim 1, After forming the semiconductor layer, And forming an etch stopper on the semiconductor layer. The method of claim 1, The semiconductor layer may be formed of any one selected from the group consisting of zinc tin oxide (ZnSnO), indium zinc oxide (InZnO), and indium gallium zinc oxide (InGaZnO ₄ ). Forming a gate electrode on the substrate; Forming an insulating film on the gate electrode; Forming a semiconductor layer including an oxide on the insulating film; Forming a metal layer on the semiconductor layer; Irradiating a laser on the metal layer corresponding to the semiconductor layer to form an ohmic layer on the semiconductor layer; And Removing the metal layer and forming a source electrode and a drain electrode connected to the semiconductor layer. Forming a gate electrode on the substrate; Forming an insulating film on the gate electrode; Forming a semiconductor layer including an oxide on the insulating film; Irradiating a laser on the semiconductor layer to form an ohmic layer; And Forming a source electrode and a drain electrode electrically connected to the semiconductor layer. The method of claim 7, wherein The laser is a UV excimer laser manufacturing method of a thin film transistor. The method of claim 7, wherein After forming the semiconductor layer, And forming an etch stopper on the semiconductor layer. The method of claim 7, wherein The semiconductor layer may be formed of any one selected from the group consisting of zinc tin oxide (ZnSnO), indium zinc oxide (InZnO), and indium gallium zinc oxide (InGaZnO ₄ ).

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