KR101623583B1 - Manufacturing Method Of Thin Film Transistor - Google Patents

Abstract

The present invention provides a method for manufacturing a semiconductor device, comprising: forming a gate electrode on a substrate; forming an insulating film on the gate electrode; forming a semiconductor layer including an oxide on the insulating film; a source electrode electrically connected to the semiconductor layer; And forming a ohmic layer in the semiconductor layer by irradiating a laser beam to the source electrode and the drain electrode corresponding to the semiconductor layer.

Oxide, thin film transistor

Description

[0001] The present invention relates to a method of manufacturing a thin film transistor,

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

In general, a thin film transistor is important not only in characteristics of a basic thin film transistor such as mobility and leakage current, but also in durability and electrical reliability that can maintain a long lifetime. Here, the semiconductor layer of the thin film transistor is mainly formed of amorphous silicon or polycrystalline silicon. The amorphous silicon has a merit that the film forming process is simple and the production cost is low, but the electrical reliability is not secured. In addition, due to the high process temperature, polycrystalline silicon is very difficult to apply in a large area, and uniformity due to the crystallization method can not be secured.

On the other hand, when a semiconductor layer is formed with an oxide, a high degree of divergence can be obtained even if the film is formed at a low temperature. Since the resistance varies depending on the content of oxygen, it is very easy to obtain desired physical properties. It is attracting great attention. In particular, examples thereof include zinc oxide (ZnO), indium zinc oxide (InZnO), indium gallium zinc oxide (InGaZnO ₄ ), and the like.

The oxide semiconductor thin film transistor has superior mobility and reliability characteristics than the conventional amorphous silicon thin film transistor, but has a problem that it is difficult to form an ohmic layer between the oxide semiconductor and the source electrode and the drain electrode. Therefore, the ohmic characteristics between the oxide semiconductor layer and the source electrode and the drain electrode are not good, so that the output characteristics of the thin film transistor are degraded.

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

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; forming an insulating film on the gate electrode; 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, To form a second layer.

According to another aspect of the present invention, there is provided a method of manufacturing a thin film transistor, including: forming a gate electrode on a substrate; forming an insulating film on the gate electrode; forming a semiconductor layer including an oxide on the insulating film Forming an ohmic layer on the semiconductor layer by irradiating a laser beam to the metal layer corresponding to the semiconductor layer, removing the metal layer, forming a source electrode connected to the semiconductor layer, And forming an electrode and a drain electrode.

According to another aspect of the present invention, there is provided a method of manufacturing a thin film transistor, including: forming a gate electrode on a substrate; forming an insulating film on the gate electrode; forming a semiconductor layer including an oxide on the insulating film Forming an ohmic layer by irradiating the semiconductor layer with a laser, and forming a source electrode and a drain electrode electrically connected to the semiconductor layer.

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

Hereinafter, 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 embodiment of the present invention.

1, a thin film transistor according to an exemplary embodiment of the present invention includes a substrate 100, a gate electrode 110 disposed on the substrate 100, an insulating layer 120 insulating the gate electrode 110, And a source electrode 140a and a drain electrode 140b which are located on the insulating layer 120 and are electrically connected to the semiconductor layer 130 including the ohmic layer 135 and the semiconductor layer 130 can do.

The thin film transistor according to an embodiment of the present invention discloses a bottom gate type thin film transistor in which a gate electrode is located at the bottom, but any structure may be applied if the source electrode and the drain electrode are located above the semiconductor layer.

Hereinafter, a method of manufacturing a thin film transistor having the 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.

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

Here, a buffer layer may be further included between the substrate 200 and the gate electrode 210. The buffer layer may be formed of an inorganic material such as silicon oxide or silicon nitride to prevent impurities such as ions from diffusing from the substrate 200 during the heat treatment process to contaminate subsequently formed elements.

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

Next, referring to FIG. 2B, a semiconductor layer 230 is formed on the insulating layer 220. Here, the semiconductor layer 230 may be formed of zinc tin oxide (ZnSnO) containing zinc oxide (ZnO), and indium (In) or gallium (Ga) may be added to improve the electrical conductivity, By doping, it can be formed to further include indium zinc oxide (InZnO) or indium gallium zinc oxide (InGaZnO ₄ ).

The source electrode 240a and the drain electrode 240b are formed so as to be electrically connected to both sides of the semiconductor layer 230 by laminating chromium (Cr), molybdenum (Mo), aluminum (Al), titanium 240b.

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

When the IR diode laser is irradiated to the source electrode 240a and the drain electrode 240b, the process 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 Lt; / RTI >

When the source electrode 240a and the drain electrode 240a are irradiated with the IR diode laser, the source electrode 240a and the drain electrode 240a made of metal act as a heat transfer medium, .

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

This ohmic layer 245 can achieve an ohmic contact between the semiconductor layer 230 and the source electrode 240a and the drain electrode 240b, thereby improving the characteristics of the thin film transistor.

3A and 3B are views showing another embodiment of the first embodiment of the present invention.

3A, a gate electrode 210 is formed on a substrate 200 and an insulating film 220 is formed on the gate electrode 210 to insulate the gate electrode 210 from the substrate 200 under the same conditions as the above- . Then, a semiconductor layer 230 including an oxide is formed on the insulating film 220.

Then, a silicon oxide film or a silicon nitride film is stacked 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 in the patterning process for forming the source electrode and the drain electrode later.

3B, chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), alloys thereof, or the like are stacked on the substrate 200 on which the etch stopper 235 is formed, A source electrode 240a and a drain electrode 240b are formed so as to be electrically connected to both sides of the gate electrode 230.

Then, an ohmic layer 245 is formed by irradiating with an IR diode laser in the same manner as in the above-described embodiment to manufacture a thin film transistor.

As described above, in the method of manufacturing a thin film transistor according to the first embodiment of the present invention, the source electrode and the drain electrode act as a heat transfer medium to form an ohmic layer in the semiconductor layer, thereby forming ohmic contact between the semiconductor layer and the source electrode and the drain electrode. So that the electrical characteristics of the thin film transistor can be improved.

4A to 4D are cross-sectional views illustrating a method of manufacturing a TFT according to a second embodiment of the present invention.

4A, a metal film such as Cr, molybdenum (Mo), indium tin oxide (ITO), or aluminum (Al) is deposited on a substrate 300. Then, a 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 may be formed of an inorganic material such as silicon oxide, silicon nitride, or the like to prevent impurities such as ions from being diffused from the substrate 300 during the heat treatment process to contaminate subsequently formed elements.

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

Next, a semiconductor layer 330 is formed on the insulating film 320. Here, the semiconductor layer 330 may be formed of zinc tin oxide (ZnSnO) containing zinc oxide (ZnO), and further doped with indium (In) or gallium (Ga) (InZnO) or indium gallium zinc oxide (InGaZnO ₄ ), as shown in FIG.

Next, a metal material is deposited on the substrate 300 on which the semiconductor layer 330 is formed, and patterned to form a metal layer 335. Here, the metal layer 335 is patterned to be positioned on a region where the source electrode and the drain electrode of the semiconductor layer 330 are in contact with each other. The metal layer 335 may be formed of chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or an alloy thereof.

4B, an ohmic layer 340 is formed by irradiating a laser beam to a region where the semiconductor layer 330 and the metal layer 335 are overlapped 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 emit light when electrons and holes recombine over an energy gap when a large amount of excess carriers are injected into the diode along the p-n junction.

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

When an IR diode laser is irradiated onto the metal layer 335, a metal layer 335 made of metal acts as a heat transfer medium to transfer the heat of the laser to the semiconductor layer 330.

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

This ohmic layer 340 has an advantage that the ohmic contact can be established between the semiconductor layer 330 and the source electrode and the drain electrode to be formed later so that the characteristics of the thin film transistor can be improved.

Referring to FIG. 4C, the laser is irradiated with the metal layer 335 by etching. Since the laser-irradiated metal layer 335 may be lifted or damaged by the high temperature of the laser, it is removed for later reliability.

4D, chromium (Cr), molybdenum (Mo), aluminum (Al), titanium (Ti), or their alloys are stacked on the semiconductor layer 330, A source electrode 345a and a drain electrode 345b are formed so as to be electrically connected to each other.

A method of manufacturing a thin film transistor according to a second embodiment of the present invention includes forming an ohmic layer on a semiconductor layer using a metal as a heat transfer medium to form a source electrode and a drain electrode of the thin film transistor and an advantage . Further, there is an advantage that the reliability of the thin film transistor can be improved by removing the laser-irradiated metal and forming the source electrode and the drain electrode.

5A through 6C are cross-sectional views illustrating a method of manufacturing a TFT according to a third embodiment of the present invention.

5A, a metal film such as Cr, molybdenum (Mo), indium tin oxide (ITO), or aluminum (Al) is deposited on a substrate 400. Then, a gate electrode 410 is formed by patterning it using a photolithography process.

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

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

Next, referring to FIG. 5B, a semiconductor layer 430 is formed on the insulating layer 420. Here, the semiconductor layer 430 may be formed of zinc tin oxide (ZnSnO) containing zinc oxide (ZnO), and further doped with indium (In) or gallium (Ga) (InZnO) or indium gallium zinc oxide (InGaZnO ₄ ), as shown in FIG.

A laser mask 440 is aligned on the substrate 400 including the semiconductor layer 430. The laser mask 440 is formed with an opening and a blocking portion so that the laser can pass therethrough, and the region through which the laser is irradiated can be adjusted through the opening. Here, the laser mask 440 adjusts the positions of the openings so that the semiconductor layer 430 is irradiated with laser light in a region where the semiconductor layer 430 is to be contacted with the source electrode and the drain electrode.

The ohmic layer 450 is formed on the semiconductor layer 430 by irradiating the semiconductor layer 430 with a laser. Here, a UV excimer laser can be used as the laser. A UV excimer laser is a laser which gives an electric stimulus to an inert gas to emit a wavelength in the UV or ultraviolet region.

When the semiconductor layer 430 is irradiated with a UV excimer laser, the UV excimer laser may be performed at a energy density of 100 to 200 mJ / cm 2 for several seconds to several minutes. Here, when the energy density of the UV excimer laser is 100 mJ or more, the carrier concentration of the semiconductor layer 430 is increased and the ohmic layer can be formed. When the energy density is 200 mJ or less, the semiconductor layer 430 can be prevented from being damaged There is an advantage.

When a UV excimer laser is irradiated on the semiconductor layer 430, the 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 the ohmic layer 450.

This ohmic layer 450 has an advantage that the ohmic contact can be established between the semiconductor layer 430 and the source electrode and the drain electrode to be formed later so that the characteristics of the thin film transistor can be improved.

5C, Cr, molybdenum, aluminum (Al), titanium (Ti), an alloy thereof, or the like is stacked on the semiconductor layer 430 on which the ohmic layer 450 is formed A source electrode 455a and a drain electrode 455b are formed so as to be electrically connected to both sides of the semiconductor layer 430. [

At this time, the source electrode 455a and the drain electrode 455b are patterned so as to be in contact with the ohmic layer 450 so that the semiconductor layer 430 and the source electrode 455a and the drain electrode 455b can be in ohmic contact with each other, Thereby forming a transistor.

6A to 6C are views showing another embodiment of the third embodiment of the present invention.

6A, a gate electrode 410 is formed on a substrate 400 and an insulating film 420 (not shown) is formed on the gate electrode 410 to insulate the gate electrode 410 under the same conditions as in the third embodiment described above. ). A semiconductor layer 430 containing an oxide is formed on the insulating layer 420.

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

6B, a laser mask 440 is aligned on a substrate 400 on which an etch stopper 435 is formed, and then a laser is irradiated to the semiconductor layer 430 in the same manner as in the second embodiment described above, The ohmic layer 450 is formed.

Next, referring to FIG. 6C, a source electrode (not shown) is formed by laminating chromium (Cr), molybdenum (Mo), aluminum (Al), titanium 455a and a drain electrode 455b are formed. At this time, the source electrode 455a and the drain electrode 455b are patterned so as to be in contact with the ohmic layer 450 so that the semiconductor layer 430 and the source electrode 455a and the drain electrode 455b can be in ohmic contact with each other, Thereby forming a transistor.

As described above, the method of manufacturing a thin film transistor according to the third embodiment of the present invention differs from the first embodiment in that a semiconductor layer is directly irradiated with a UV excimer laser to form an ohmic layer, And an ohmic contact between the drain electrode and the drain electrode, thereby improving the electrical characteristics of the thin film transistor.

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

<Experimental Example>

Molybdenum (Mo) was sputtered on the substrate to form a gate electrode of 10 nm. Silicon nitride (SiNx) was deposited as a gate insulating film by PECVD at 300 ° C to form a 400 nm nitride film. IGZO was deposited to a thickness of 500 angstroms Layer. Then, molybdenum (Mo) was sputter-deposited to form a source electrode and a drain electrode with a thickness of 2000 angstroms. Then, a thin film transistor was manufactured by irradiating an IR diode laser with a wavelength of 800 nm and a power of 8 V and a scan speed of 100 m / s on the source electrode and the drain electrode.

<Comparative Example>

A thin film transistor was fabricated without the process of irradiating an IR diode laser under the same process conditions as in the above-mentioned experimental example.

The output characteristics of the thin film transistor fabricated according to the experimental examples and the comparative examples are measured and shown in FIGS. 7A and 7B.

Referring to FIGS. 7A and 7B, the output characteristics of the thin film transistor measuring the source-drain current according to the gate voltage are shown in FIG. 7A. In FIG. 7A, the source-drain current is continuously increased However, it can be seen that the increase amount of the source-drain current in the comparative example of FIG. 7B is not remarkable in the experimental example.

As described above, the method of manufacturing a thin film transistor according to an embodiment of the present invention can improve the contact area between the semiconductor layer and the source electrode and the drain electrode, and can provide 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. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

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

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

7A and 7B are graphs showing output characteristics of a thin film transistor fabricated according to Experimental Examples and Comparative Examples of the present invention.

Claims (13)

delete delete delete delete delete 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 layer; Forming a patterned metal layer to be in contact with a region of the semiconductor layer to which the source electrode and the drain electrode are to be contacted; Forming an ohmic layer on the semiconductor layer by irradiating a laser beam onto the metal layer that is in contact with the semiconductor layer; Etching and removing the metal layer irradiated with the laser; And And forming a source electrode and a drain electrode in contact with the ohmic layer of the semiconductor layer from which the metal layer is removed. delete delete delete delete The method according to claim 6, Wherein the laser is an IR diode laser. The method according to claim 6, Wherein the metal layer is a heat transfer medium for transferring heat of the laser to the semiconductor layer. The method according to claim 6, Wherein the semiconductor layer is 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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