KR102256554B1 - Tin oxide layer, tft having the same as channel laeyr, and manufacturing method for the tft - Google Patents

Abstract

It provides a tin oxide layer, a thin film transistor including the same as a channel layer, and a method of manufacturing the thin film transistor. The thin film transistor includes a gate electrode, a tin (II) oxide channel layer, which is a polycrystalline thin film disposed on the gate electrode and first grown in a [001] direction, a gate insulating film insulating film disposed between the gate electrode and the channel layer, and the It includes source and drain electrodes electrically connected to both ends of the channel layer, respectively.

Description

Tin oxide layer, a thin film transistor including the same as a channel layer, and a method of manufacturing a thin film transistor {TIN OXIDE LAYER, TFT HAVING THE SAME AS CHANNEL LAEYR, AND MANUFACTURING METHOD FOR THE TFT}

The present invention relates to a semiconductor layer and a semiconductor device including the same, and more particularly, to a thin film transistor.

As the silicon film used as the semiconductor film of the transistor, an amorphous silicon film or a polycrystalline silicon film is used depending on the purpose. Recently, as an example of a material other than silicon, research has been conducted on using an oxide semiconductor as a channel layer of a transistor. Oxide semiconductors have excellent transparency and are mainly used in display devices.

In order to construct a circuit with an oxide semiconductor, not only an n-type semiconductor but also a p-type semiconductor is required, but oxide semiconductors are mostly n-type semiconductors, and it is known that it is somewhat difficult to implement a p-type oxide semiconductor.

[Patent Document] KR 10-1284587

An object to be solved by the present invention is to provide a method of manufacturing a tin oxide layer having excellent thin film uniformity and growth rate.

Another problem to be solved by the present invention is to provide a tin oxide layer with improved charge mobility.

Another problem to be solved by the present invention is to provide a thin film transistor including a tin oxide layer channel layer with improved charge mobility.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, an aspect of the present invention provides a thin film transistor. The thin film transistor includes a gate electrode, a tin (II) oxide channel layer, which is a polycrystalline thin film disposed on the gate electrode and first grown in a [001] direction, a gate insulating film insulating film disposed between the gate electrode and the channel layer, and the It includes source and drain electrodes electrically connected to both ends of the channel layer, respectively.

In addition to the [001] direction, the tin (II) oxide channel layer may include at least one type of crystal grains grown in the [101], [110], and [103] directions. In the XRD (X-ray diffraction) spectrum of the tin (II) oxide channel layer, [101] and [110] peaks may be combined to appear as one peak.

In order to achieve the above technical problem, an aspect of the present invention provides a method of manufacturing a thin film transistor. The thin film transistor includes a gate electrode, a gate insulating layer, a channel layer, and source and drain electrodes. In the channel layer, a tin precursor is supplied in a state in which the substrate on which the channel layer is to be formed is inserted into the chamber and the outlet of the chamber is closed to increase the reaction pressure in the chamber to adsorb the tin precursor onto the substrate surface. Precursor pressure dosing step; After the tin precursor pressure dosing step, a tin precursor purge step of purging the chamber; After the tin precursor purge step, an oxidizing agent supply step of supplying an oxidizing agent into the chamber to oxidize the tin precursor adsorbed on the substrate to form tin oxide; And after the step of supplying the oxidizing agent, a unit cycle including a step of purging the oxidizing agent for purging the chamber is performed a plurality of times to form a tin oxide layer, and then the tin oxide layer is formed by heat treatment. The channel layer is a tin (II) oxide channel layer, which is a polycrystalline thin film that has been preferentially grown in the [001] direction.

In addition to the [001] direction, the tin (II) oxide channel layer may include at least one type of crystal grains grown in the [101], [110], and [103] directions. In the XRD (X-ray diffraction) spectrum of the tin (II) oxide channel layer, [101] and [110] peaks may be combined to appear as one peak.

The tin precursor may be a tin (II)-organic compound or a tin (IV)-organic compound. The tin precursor may have at least one [((C ₁ -C ₅ )alkyl) _n silyl] _m amino group (n is 1, 2, or 3 and m is 1 or 2) as a ligand. The ligand may be [((C ₁ -C ₅ )alkyl) _n silyl] _m amino group (n is 3 and m is 2). The tin precursor may be (TMSA) ₂ Sn(II) (bis[bis(trimethylsilyl)amino]tin(II)).

The heat treatment may be performed in a temperature range of more than 280 degrees and not more than 400 degrees in an inert gas atmosphere.

The tin precursor pressure dosing step and the tin precursor purge step constitute a tin precursor sub-cycle, and before the oxidizing agent supply step, the tin precursor sub-cycle may be performed a plurality of times. The oxidizing agent supply step may proceed to the oxidizing agent pressurized dosing step performed in a state in which the reaction pressure in the chamber is increased by supplying the oxidizing agent while the outlet of the chamber is closed. The step of dosing with the oxidant pressure and the step of purging the oxidant constitute an oxidant sub-cycle, and the unit cycle may include performing the oxidant sub-cycle a plurality of times in succession.

In order to achieve the above technical problem, an aspect of the present invention provides a tin (II) oxide layer. The tin (II) oxide layer is a polycrystalline thin film that is preferentially grown in the [001] direction, but in addition to the [001] direction, at least one kind of crystal grains grown in the [101], [110], and [103] directions It has crystal grains. In the tin (II) oxide layer, peaks [101] and [110] in an X-ray diffraction (XRD) spectrum may be combined to appear as one peak.

As described above, according to an embodiment of the present invention, a tin oxide layer can be formed with excellent thin film uniformity and growth rate.

As described above, according to an embodiment of the present invention, a tin oxide layer with improved charge mobility may be provided.

As described above, according to an embodiment of the present invention, it is possible to provide a thin film transistor including a tin oxide layer with improved charge mobility.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1A is a timing diagram illustrating injection of a metal precursor gas, injection of a purge gas, and injection of an oxidizer gas for manufacturing a tin oxide layer according to an exemplary embodiment of the present invention.
1B is a timing diagram illustrating injection of a metal precursor gas, injection of a purge gas, and injection of an oxidizer gas for manufacturing a tin oxide layer according to another exemplary embodiment of the present invention.
2 is a schematic diagram showing a thin film manufacturing apparatus according to an embodiment of the present invention.
3 is a cross-sectional view showing a thin film transistor according to an embodiment of the present invention.
4 is a table showing the parameters of a unit cycle for manufacturing a tin oxide thin film according to the present preparation example.
5 is a graph showing the thickness of the tin oxide thin film according to the number of unit cycles according to the manufacturing example of the tin oxide thin film.
6A and 6B show XPS (X-ray Photoelectron Spectroscopy) spectra and high-resolution XPS spectra of the tin oxide thin film according to the tin oxide thin film preparation example, respectively.
7 is an atomic force microscopy (AFM) image of a tin oxide thin film according to a tin oxide thin film manufacturing example.
8 shows an XRD (X-ray diffraction) spectrum of a thin film according to Preparation Example B of a tin oxide thin film.
9 shows Id-Vg curves showing the transfer characteristics of TFTs according to TFT Manufacturing Examples 1 to 6;
10 shows Id-Vg curves showing transfer characteristics of TFTs according to TFT Manufacturing Examples 7 to 11.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings in order to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. In the drawings, when a layer is said to be “on” another layer or substrate, it may be formed directly on the other layer or substrate, or a third layer may be interposed therebetween. In the present embodiments, "first", "second", or "third" is not intended to impose any limitation on the elements, but should be understood as terms for distinguishing the elements.

In the case of describing "Cx-Cy" in the present specification, a case having a number of carbon atoms corresponding to all integers between the carbon number x and the carbon number y should be interpreted as being described together.

1A is a timing diagram illustrating injection of a metal precursor gas, injection of a purge gas, and injection of an oxidizer gas for manufacturing a tin oxide layer according to an exemplary embodiment of the present invention. 1B is a timing diagram illustrating injection of a metal precursor gas, injection of a purge gas, and injection of an oxidizer gas for manufacturing a tin oxide layer according to another exemplary embodiment of the present invention. 2 is a schematic diagram showing a thin film manufacturing apparatus according to an embodiment of the present invention.

1A, 1B, and 2, the substrate S may be loaded on the stage 102 in the chamber 100 including the gas inlet 120 and the gas outlet 140. Before loading the substrate S, the chamber 100 may be heated and maintained at a deposition temperature by the control unit 150. The deposition temperature may be 20 to 250 °C, 50 to 200 °C, 80 to 150 °C, 90 to 100 °C, or 95 to 105 °C. The gas outlet 140 may be connected to a vacuum pump.

First, all gas inlet valves 130, 132, 134 connected to the gas inlet 120 are closed, and the gas outlet valve 142 connected to the gas outlet 140 is opened to make the interior of the chamber 100 in a vacuum state. have.

Thereafter, in a state where the tin precursor gas control valve 130 is opened and the gas outlet valve 142 is closed, the tin precursor gas may be supplied into the chamber 100 from the tin precursor storage unit 110. The tin precursor is a tin-organic compound, and may be a tin (II)-organic compound or a tin (IV)-organic compound. As an example, the tin precursor includes tin (II) or tin (IV) as a central metal ion, and as a ligand [((C ₁ -C ₅ )alkyl) _n silyl] _m amino group (n is 1, 2, or 3 and m is 1 or 2), silyl (C ₁ -C ₅ ) alkylamino group, (silyl (C ₁ -C ₅ ) alkyl) _m amino group (m is 1 or 2), ((C ₁ -C ₅ ) alkyl ) _m amino group (m is 1 or 2), (C ₁ -C ₅ ) alkylalkoxy group, and ((C ₁ -C ₅ )alkyl) _m amino (C ₁ -C ₅ )alkoxy group (m is 1 or 2 ) May have at least one ligand selected from the group consisting of. The tin precursor is, for example, (TMSA) ₂ Sn(II) (bis[bis(trimethylsilyl)amino]tin(II)), TDEASn(IV) (Tetrakis(diethylamino)tin(IV)), TDMASn(IV) (Tetrakis(dimethylamido)tin(IV)), Sn(acac) ₂ (Tin(II) acetylacetonate), Sn(edpa) ₂ (bis(N-ethoxy-2,2-dimethyl propanamido)tin(II), Sn( dmamp) ₂ (bis(dimethylamino-2-methyl-2-propoxy)tin(II)), or a combination thereof. In one embodiment, the tin precursor is a ligand [((C ₁ -C ₅ ) Alkyl) _n silyl] _m amino group (n is 1, 2, or 3 and m is 1 or 2) may be provided with at least one, specifically two. As an example, the ligand is [((C _1- C ₅ )alkyl) _n silyl] _m may be an amino group (n is 3 and m is 2) Specifically, the tin precursor may be (TMSA) ₂ Sn(II).

The tin precursor may be stored in a solid or liquid state in the tin precursor storage unit 110. The tin precursor storage unit 110 is heated to less than the pyrolysis temperature of the tin precursor, and accordingly, the tin precursor may be supplied into the chamber 100 at a predetermined vapor pressure. In this case, the supplied tin precursor may be supplied without a carrier gas. Since the tin precursor is supplied while the gas outlet valve 142 is closed, it is possible to increase the pressure in the chamber 100 while accumulating in the chamber 100. The tin precursor may be supplied until the pressure of the chamber 100 reaches the reaction pressure (P _M ) (tin precursor supply step, MD ₁ ). The reaction pressure, that is, the pressure of the tin precursor gas is in the range of tens to several hundred mTorr, specifically 20 to 200 mTorr, 25 to 150 mTorr, 30 to 120 mTorr, 35 to 100 mTorr, 40 to 80 mTorr, or 45 to 60 mTorr days. I can.

When the reaction pressure is reached, the tin precursor gas control valve 130 may be closed and the chamber may be sealed for a predetermined time (tin precursor exposure step, ME ₁ ). The tin precursor supply step (MD ₁ ) and the tin precursor exposure step (ME ₁ ) may be referred to as a tin precursor pressure dosing step. However, the tin precursor exposure step ME ₁ may be omitted in some cases.

In the tin precursor pressurized dosing step, that is, in the tin precursor supply step (MD ₁ ) and the tin precursor exposure step (ME ₁ ), the tin precursor gas is chemisorption and self-saturation on the surface of the substrate or a layer previously formed on the substrate. It can be deposited by a self-saturated reaction. Since the chemical adsorption and self-saturation reaction of the tin precursor gas proceeds in a pressurized environment, specifically, a pressurized stagnant environment rather than a lamina flow environment, the substrate of the tin precursor gas or a layer previously formed on the substrate The chemical adsorption rate or surface coverage to the surface can be greatly improved.

After this, the chamber can be purged (tin precursor purge step, MP ₁ ). Specifically, by opening the purge gas control valve 132 and the gas outlet valve 142, the purge gas in the purge gas storage unit 112 flows onto the surface of the substrate in the chamber, so that the excess tin precursor gas that cannot be adsorbed on the surface of the substrate. And a reaction product generated by the reaction between the tin precursor gas and the substrate surface. In this case, the purge gas may be an inert gas, and the inert gas may include, for example, argon (Ar), nitrogen (N ₂ ), or a combination thereof.

The tin precursor pressure dosing step (MD ₁ , ME ₁ ) and the tin precursor purge step (MP ₁ ) may constitute a tin precursor sub-cycle (M-SC ₁ ), and the tin precursor sub-cycle (M-SC _n ) is 1 to multiple times, specifically 1 to 10 times (n=1 to 10), for example, 2 to 7 times (n=2 to 7), or 3 to 5 times (n=3 to 5) have. The plurality of tin precursor sub-cycles (M-SC _n ) may constitute a tin precursor unit cycle (M-UC). When performing the tin precursor sub-cycles a plurality of times (M-SC ₁ , M-SC ₂ , ... M-SC _n , n≥2), in an embodiment as shown in FIG. 1A, the tin precursor pressure dosing steps ( _{The reaction pressure (P M} ) in MD ₁ , MD ₂ ,… MD _n , ME1, ME2,… MEn, n≥2) may be substantially the same, and in an embodiment as shown in FIG. 1B, the tin precursor is pressurized. _{The reaction pressures (P M1} , P _M2 , P _M3 ) in the dosing steps (MD ₁ , MD ₂ ,… MD _n , ME1, ME2,… MEn, n≥2) may be different from each other. _{In Figure 1b, the reaction pressure (P M1} , P _M2 , P _M3 ) gradually increases as the number of tin precursor pressurized dosing steps (MD ₁ , MD ₂ ,… MD _n , ME1, ME2,… MEn, n≥2) increases. Although shown to increase, the reaction pressure is not limited thereto, and the reaction pressure may be gradually decreased.

_{After performing the tin precursor unit cycle (M-UC), an oxidizing agent supply step (oxidizing agent supply step, OD 1} ) of forming a tin oxide unit layer by oxidizing the tin precursor adsorbed on the substrate by supplying an oxidizing agent into the chamber is performed. You can do it. In an embodiment, with the oxidizer gas control valve 134 open and the gas outlet valve 142 closed, the oxidizer gas may be supplied into the chamber 100 from the oxidizer storage unit 114. Since the oxidizing agent is supplied while the gas outlet valve 142 is closed, it is possible to increase the pressure in the chamber 100 while accumulating in the chamber 100. The oxidizing agent may be supplied until the pressure in the chamber 100 reaches the reaction pressure P _OX. The reaction pressure, that is, the pressure of the oxidant gas, may be in the range of one hundred mTorr to several Torr, specifically 100 mTorr to 1 Torr, 150 to 500 mTorr, 200 to 400 mTorr, or 250 to 350 mTorr.

The oxidizing agent may be H ₂ O, H ₂ O ₂ , or O ₃ but is not limited thereto. In one embodiment, the oxidizing agent may be _{H 2 O.} When the oxidizing agent is H ₂ O or H ₂ O ₂ , the oxidizing agent may be stored in a liquid state in the oxidizing agent storage unit 114. The oxidizing agent storage unit 114 is heated and the oxidizing agent may be supplied into the chamber 100 at a predetermined vapor pressure. In one embodiment, the supplied oxidizing agent may be supplied without a carrier gas.

When the reaction pressure P _OX is reached, the oxidant gas control valve 134 may be closed and the chamber may be sealed for a predetermined time (oxidant exposure step, OE ₁ ). The oxidant supply step (OD ₁ ) and the oxidant exposure step (OE ₁ ) may be referred to as an oxidant pressure dosing step. However, the oxidizing agent exposure step OE ₁ may be omitted in some cases.

In the oxidizer pressurized dosing step, that is, in the oxidizing agent supply step (OD ₁ ) and the oxidizer exposure step (OE ₁ ), the oxidizing agent gas reacts with the tin precursor layer formed on the substrate to oxidize the tin precursor layer to a tin oxide unit layer. I can. In this way, the reaction of the oxidizer gas with the tin precursor layer may be performed in a pressurized environment, specifically, a pressurized stagnant environment rather than a lamina flow environment. However, the present invention is not limited thereto, and the oxidant gas may be supplied with the gas outlet valve 142 open to react with the tin precursor layer while forming a lamina flow in the chamber.

After this, the chamber can be purged (oxidant purging step, OP ₁ ). Specifically, by opening the purge gas control valve 132 and the gas outflow valve 142, the purge gas in the purge gas storage unit 112 flows onto the substrate surface, so that the excess oxidizing agent gas and oxidizing agent that did not react with the tin precursor layer It is possible to remove reaction products produced by the reaction between metal precursors. In this case, the purge gas may be an inert gas, and the inert gas may include, for example, argon (Ar), nitrogen (N ₂ ), or a combination thereof.

The oxidant pressurized dosing step (OD ₁ , OE ₁ ), and the oxidant purge step (OP ₁ ) may constitute an oxidant sub-cycle (O-SC ₁ ), and the oxidant sub-cycle (O-SC _n ) is 1 to A number of times, specifically 1 to 10 times (n=1 to 10), for example, 2 to 7 times (n=2 to 7), or 3 to 5 times (n=3 to 5) may be performed. The plurality of oxidant sub-cycles (O-SC _n ) may constitute an oxidant unit cycle (O-UC). When performing the oxidant sub-cycle multiple times (O-SC ₁ , O-SC ₂ ,… O-SC _n , n≥2), in an embodiment as shown in FIG. 1A, the oxidant pressure dosing steps (OD ₁ , OD ₂ ,… OD _n , OE ₁ , OE ₂ ,… OE _n , n≥2) at the reaction pressure (P _OX ) may be substantially the same, and in an embodiment as shown in FIG. 1B, the oxidizing agent is pressurized. The reaction pressures (P _OX1 , P _OX2 , P _OX3 ) at the dosing steps (OD ₁ , OD ₂ ,… OD _n , OE ₁ , OE ₂ ,… OE _n , n≥2) may be different. In Figure 1b, as the number of dosing steps (OD ₁ , OD ₂ ,… OD _n , OE ₁ , OE ₂ ,… OE _n , n≥2) increases, the reaction pressure (P _OX1 , P _OX2 , P _OX3 ) Although it is shown to increase gradually, the reaction pressure is not limited thereto, and the reaction pressure may be gradually decreased.

When the tin precursor unit cycle (M-UC) and the oxidant unit cycle (O-UC) are performed once, the thickness of the tin oxide layer is about 0.2 to 0.5 Å, specifically 2.5 to 4.5 Å. Can be formed. Thereafter, the metal precursor unit cycle (M-UC) and the oxidant unit cycle (O-UC) may be alternately repeated. The number of repetitions may determine the final thickness of the tin oxide layer. Since the metal precursor gas was adsorbed at least in a pressurized stagnant environment in which the reaction pressure was increased in the tin oxide layer formed as described above, this is a general ALD method, that is, the tin precursor is removed in a lamina flow environment rather than a pressurized environment. When dosing, it is possible to obtain a very large thickness per unit cycle compared to the thickness of about 1 Å obtained, and further, the surface roughness is 0.1 to 0.5 nm (RMS) as an example, and 0.2 to 0.3 as an example. It can exhibit excellent surface morphology, such as showing a very low value of the order of nm (RMS).

The tin oxide layer formed by the method described with reference to FIGS. 1A and 1B may be heat treated. The heat treatment may be performed in an argon atmosphere as an example of an inert gas. The heat treatment may be performed at more than 280 degrees and not more than 400 degrees, for example, 300 to 350 degrees, 290 to 330 degrees, 295 to 310 degrees, or 300 to 305 degrees.

By this heat treatment, a polycrystalline tin oxide layer can be obtained. The polycrystalline tin oxide layer may be a tin (II) oxide layer, that is, a SnO layer, which is preferentially grown in the [001] direction. In addition, the tin oxide layer may be a p-type semiconductor layer. Specifically, in addition to the [001] direction, at least one of crystal grains grown in the [101], [110], and [103] directions may be provided in the tin oxide layer.

The tin oxide layer may exhibit at least one of [101], [110], and [103] peaks in addition to the [001] peak in the X-ray diffraction (XRD) spectrum. In this case, the peaks [101] and [110] may be combined to appear as one peak. Specifically, one peak may appear in a region where 2θ reaches about 25 to 35 degrees. In addition, [001] peaks having different intensities, in particular, [101] peaks and/or [103] peaks have a high contrast intensity, and the half width of [001] peaks is [101] peaks and/or [103] peaks. It can be smaller than half the width. Specifically, the half width of the [001] peak may represent a value of about 1 degree or less, for example, 0.1 to 0.9, 0.2 to 0.85, 0.3 to 0.8, 0.4 to 0.75, 0.5 to 0.7, 0.6 to 0.65 degrees.

3 is a cross-sectional view showing a thin film transistor according to an embodiment of the present invention.

Referring to FIG. 3, a substrate 10 may be provided. The substrate may be a semiconductor substrate, a metal substrate, a glass substrate, or a flexible substrate. For example, the flexible substrate may be a polymer substrate, for example, a PET (polyethylene terephthalate) or PI (polyimide) substrate. Devices for operation circuits, etc. may be formed on the substrate 10, a protective layer (not shown) such as an insulating film covering the substrate may be formed, or a protective layer may be formed to cover the device and the device. .

The surface of the substrate 10 may be cleaned and surface treated as necessary.

A gate electrode 20 extending in one direction may be formed on the substrate 10. The gate electrode 20 may be formed using Al, Cr, Cu, Ta, Ti, Mo, W, or an alloy thereof. A gate insulating layer 30 may be formed on the gate electrode 20. The gate insulating film 30 may be a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, or a composite film thereof. The gate insulating layer 30 may be formed using an atomic layer deposition method, and may be an aluminum oxide layer as an example.

A tin oxide channel layer 40 patterned to cross the upper portion of the gate electrode 20 may be formed on the gate insulating layer 30. However, the lower layer on which the tin oxide channel layer 40 is formed may vary depending on the shape of the thin film transistor. The tin oxide channel layer 40 is formed by performing a pressurized ALD as described with reference to FIGS. 1A or 1B on a substrate including the gate insulating layer 30 to form a tin oxide layer, heat treatment, and then patterning. can do. The heat treatment may be performed in an argon atmosphere as an example of an inert gas. The heat treatment may be performed at more than 280 degrees and not more than 400 degrees, for example, 300 to 350 degrees, 290 to 330 degrees, 295 to 310 degrees, or 300 to 305 degrees.

The tin oxide layer after deposition according to the pressurized ALD and before heat treatment may be a layer including an amorphous matrix and crystal grains crystallized in different directions dispersed in the amorphous matrix.

Meanwhile, in a heat treatment process, the tin oxide channel layer 40 may change into a polycrystalline thin film forming a grain boundary as crystal grains crystallized in different directions dispersed in the amorphous matrix grow. The tin oxide channel layer 40 is an example of a tin (II) oxide layer that is preferentially grown in the [001] direction, and may be a SnO layer. In addition, the tin oxide channel layer 40 may be a p-type semiconductor layer. Specifically, in addition to the [001] direction, the tin oxide channel layer 40 may include at least one of crystal grains grown in the [101], [110], or [103] direction. The tin oxide channel layer 40 may exhibit at least one peak among [101], [110], and [103] peaks in addition to the [001] peak in an X-ray diffraction (XRD) spectrum. In this case, the peaks [101] and [110] may be combined to appear as one peak. Specifically, one peak may appear in a region where 2θ reaches about 25 to 35 degrees. In addition, [001] peaks having different intensities, in particular, [101] peaks and/or [103] peaks have a high contrast intensity, and the half width of [001] peaks is [101] peaks and/or [103] peaks. It can be smaller than half the width. Specifically, the half width of the [001] peak may represent a value of about 1 degree or less, for example, 0.1 to 0.9, 0.2 to 0.85, 0.3 to 0.8, 0.4 to 0.75, 0.5 to 0.7, 0.6 to 0.65 degrees. The tin oxide channel layer 40 may have a thickness of 7 nm or more, 7 to 50 nm, 8 to 20 nm, or 9 to 15 nm.

A source electrode 50S and a drain electrode 50D may be formed on both ends of the tin oxide channel layer 40. The source electrode (S) and the drain electrode (D) are at least one of aluminum (Al), neodymium (Nd), silver (Ag), chromium (Cr), titanium (Ti), tantalum (Ta), and molybdenum (Mo). As an example of a single metal, an alloy containing them, or a metal oxide conductive film, it may be formed using ITO (Indium Tin Oxide).

As an example of the thin film transistor in FIG. 3, a bottom gate-top contact type, that is, a bottom gate staggered thin film transistor is shown, but is not limited thereto, and a bottom gate-bottom contact type (bottom gate coplanar), It can also be applied to a top gate-bottom contact type (top gate staggered) or a top gate-top contact type (top gate coplanar) type thin film transistor. In the case of the top gate type, the superlattice channel layer 30 may be disposed to cross the lower portion of the gate electrode G. Furthermore, the thin film transistor may be transformed into various shapes such as a vertical thin film transistor.

Hereinafter, a preferred experimental example is presented to aid in understanding of the present invention. However, the following experimental examples are only intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

Tin Oxide Thin Film Preparation Example A

4 is a table showing the parameters of a unit cycle for manufacturing a tin oxide thin film according to the present preparation example.

A silicon substrate was loaded into a chamber having a gas inlet and a gas outlet, and the chamber was heated to 100°C. With the gas outlet closed, the tin (II) precursor Sn(II)(TMSA) ₂ (bis[bis(trimethylsilyl)amino]tin(II)) was supplied onto the substrate through the gas inlet. At this time, the tin (II) precursor was supplied without a carrier gas, and supplied until the pressure in the chamber reached 50 mTorr. After that, the tin (II) precursor was reacted on the substrate surface for 5 seconds while maintaining the chamber pressure at 50 mTorr by closing the chamber inlet. Thereafter, with both the gas inlet and the gas outlet open, a metal subcycle was performed in which argon as a purge gas was supplied to the gas inlet for 40 seconds to purge the reaction by-products and the residual reaction gas. The metal sub-cycle was repeated 4 times to form a tin atom layer.

Thereafter, with the gas outlet closed, an oxidizing agent H ₂ O was supplied onto the tin atomic layer through the gas inlet. At this time, the oxidizing agent was supplied without a carrier gas, and was supplied until the pressure in the chamber reached 300 mTorr. Thereafter, the inlet of the chamber was also closed, and H ₂ O was reacted on the surface of the tin atomic layer for 2 seconds while maintaining the chamber pressure at 300 mTorr. Thereafter, while both the gas inlet and the gas outlet were opened, argon, a purge gas, was supplied to the gas inlet for 40 seconds to perform an oxidizing agent sub-cycle purging the reaction by-products and residual reaction gas. The oxidizing agent subcycle was repeatedly performed 4 times to form a tin oxide atomic layer.

The four metal sub-cycles and the four oxidizer sub-cycles constitute a unit cycle for manufacturing a tin oxide thin film.

5 is a graph showing the thickness according to the number of unit cycles of a tin oxide thin film according to a tin oxide thin film manufacturing example. Specifically, the thickness of the tin oxide thin films obtained by repeating 100 times, 300 times, 500 times, and 1000 times of a unit cycle according to the tin oxide thin film preparation example was measured and plotted.

Referring to FIG. 5, when the deposition temperature was 100° C., the growth rate per unit cycle of the tin oxide atomic layer was 0.4 Å/cycle.

6A and 6B show XPS (X-ray Photoelectron Spectroscopy) spectra and high-resolution XPS spectra of the tin oxide thin film according to the tin oxide thin film preparation example, respectively. In this case, the tin oxide thin film is a thin film obtained by performing 350 unit cycles described in the tin oxide thin film manufacturing example.

6A and 6B, it can be seen that the tin oxide thin film according to the tin oxide thin film preparation example contains Sn and O.

7 is an atomic force microscopy (AFM) image of a tin oxide thin film according to a tin oxide thin film manufacturing example. In this case, the tin oxide thin film is a thin film having a thickness of about 14 nm obtained by performing 350 unit cycles described in the tin oxide thin film manufacturing example.

Referring to FIG. 7, the tin oxide thin film exhibited a root mean square (RMS) value of about 0.24 Å, indicating that a thin film having a very low surface roughness was formed.

Tin Oxide Thin Film Preparation Example B

The thin film according to the tin oxide thin film Preparation Example A was heat-treated at 300° C. for 5 hours at 1 Torr pressure in an argon atmosphere.

8 shows an XRD (X-ray diffraction) spectrum of a thin film according to Preparation Example B of a tin oxide thin film.

Referring to FIG. 8, it can be seen that the thin film according to the tin oxide thin film Preparation Example B exhibits peaks [001], [101], [110], [002] and [103], which are characteristic peaks of tin (II) oxide. I can. At this time, it can be seen that the peaks [101] and [110] are combined to appear as one peak. Specifically, it can be seen that one peak appears in a region where 2θ reaches about 25 to 35 degrees. In this tin oxide thin film, it can be seen that the intensity of the [001] peak is higher than that of the other peaks, and in particular, it can be seen that the intensity of the [101] peak and the [103] peak is higher. In addition, it can be seen that the half width of the [001] peak is smaller than the half width of the [101] or [103] peak. Specifically, the half width of the [001] peak seems to be about 0.62 degrees. From these results, it can be seen that the thin film according to the tin oxide thin film Preparation Example B is a polycrystalline tin (II) oxide thin film that is first grown in the [001] direction.

TFT Manufacturing Examples 1 to 11

After providing the glass substrate, the glass substrate was subjected to solvent ultrasonic cleaing and UV ozone treatment. The treated glass substrate was placed in a high vacuum ( ^{less than 1×10 −6} Torr) atmosphere, and an aluminum pattern having a thickness of 70 nm was deposited on the glass substrate using a thermal evaporation method using a shadow mask to form a gate electrode. _{An Al 2} O ₃ layer having a thickness of 10 nm, which is a gate insulating film, was formed on the gate electrode by using the ALD method. Specifically, the Al ₂ O ₃ layer is reacted by supplying a mixture gas of trimethylaluminum (TMA), Aldrich, 97%, which is an aluminum precursor, and argon, which is a carrier gas, for 2 seconds, and argon, which is a purge gas, for 20 seconds. By-products and residual reaction gas are purged, _{a mixture gas of H 2} O as an oxidizing agent and argon as a carrier gas is supplied for 2 seconds, and argon as a purge gas is supplied for 40 seconds to purify the reaction by-products and residual reaction gas ( ALD) unit cycle was formed by repeating 27 times. _{The Al 2} O ₃ inorganic nanolayer was grown to a thickness of about 0.1 nm per ALD unit cycle.

_{After forming the SnO thin film by performing the unit cycle described in SnO thin film Preparation Example A on the Al 2} O ₃ layer as the gate insulating layer as many times as shown in Table 1 below, it is shown in Table 1 below at 1 Torr pressure in an argon atmosphere. An SnO channel layer was formed by heat treatment at temperature for 5 hours. Finally, Al source/drain electrodes having a thickness of 70 nm were formed on the channel layer by thermal evaporation.

Number of unit cycle repetitions SnO thin film thickness (Å) Heat treatment temperature
(℃) I _on /I _off
Mobility
(cm ² V ^-1 S ^-1 ) TFT production example 1 125 5 300 - - TFT production example 2 175 7 300 1.1 × 10 ³ 0.41 TFT production example 3 200 8 300 1.1 × 10 ³ 0.86 TFT production example 4 225 9 300 0.56 × 10 ³ 1.21 TFT
Manufacturing Example 5 250
10 300 0.13 × 10 ³ 1.3 TFT
Manufacturing Example 6 375 15
300 0.15 × 10 ³ 1.36 TFT
Manufacturing Example 7 375 15
280 0.0105
× 10 ³ 0.75 TFT
Manufacturing Example 8 375 15
300 0.16 × 10 ³ 1.51 TFT production example 9 375 15
310 0.22 × 10 ³ 1.05 TFT production example 10 375 15
330 0.14 × 10 ³ 0.61 TFT production example 11 375 15
350 0.16 × 10 ³ 0.25

9 shows Id-Vg curves showing the transfer characteristics of TFTs according to TFT Manufacturing Examples 1 to 6;

Referring to FIG. 9 and Table 1, it can be seen that the TFT including the SnO channel layer exhibits P-type transmission characteristics, and when the thickness of the SnO channel layer is 7 nm or more, distinguishable on and off states appear. In addition, when the thickness of the SnO channel layer is 10 nm or more, it seems that the charge mobility saturation appears.

10 shows Id-Vg curves showing the transfer characteristics of TFTs according to TFT Manufacturing Examples 7 to 11.

Referring to FIG. 10 and Table 1, when the temperature for heat treatment of the SnO channel layer exceeds 280 degrees and further exceeds 300 degrees, the I _on /I _off value appears to represent 2 orders of magnitude, exceeding 280 and 330. It can be seen that less than, specifically, at 290 to 320 degrees, particularly 300 to 310 degrees, exhibits a charge mobility of 1 or more, and as an example, it can be seen that the most excellent charge mobility is shown at 295 to 305 and particularly 300 degrees.

Above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and changes by those of ordinary skill in the art within the spirit and scope of the present invention This is possible.

Claims (18)

A gate electrode;
Tin (II) oxide channel, a polycrystalline thin film that is disposed on the gate electrode and is first grown in the [001] direction, and appears as one peak by combining the [101] and [110] peaks in the X-ray diffraction (XRD) spectrum layer;
A gate insulating layer insulating layer disposed between the gate electrode and the channel layer; And
A thin film transistor including source and drain electrodes electrically connected to both ends of the channel layer, respectively. The method according to claim 1,
The tin (II) oxide channel layer is a thin film transistor further comprising crystal grains grown in a [103] direction. delete The method according to claim 1,
[001] In the XRD (X-ray diffraction) spectrum of the tin (II) oxide channel layer, the [001] peak is a thin film transistor having a half width of 0.1 to 1 degree. In the method of manufacturing a thin film transistor comprising a gate electrode, a gate insulating film, a channel layer, and source and drain electrodes,
The channel layer,
A tin precursor pressurized dosing step of supplying a tin precursor in a state where the channel layer is formed in a chamber and closing the outlet of the chamber to increase the reaction pressure in the chamber to adsorb the tin precursor onto the substrate surface; After the tin precursor pressure dosing step, a tin precursor purge step of purging the chamber; After the tin precursor purge step, an oxidizing agent supply step of supplying an oxidizing agent into the chamber to oxidize the tin precursor adsorbed on the substrate to form tin oxide; And after the step of supplying the oxidizing agent, performing a unit cycle including a step of purging the oxidizing agent for purging the chamber a plurality of times to form a tin oxide layer,
Forming the tin oxide layer by heat treatment,
[001] A method of manufacturing a thin film transistor, which is a tin (II) oxide channel layer, which is a polycrystalline thin film grown first in the [001] direction. The method of claim 5,
In addition to the [001] direction, the tin (II) oxide channel layer includes at least one of crystal grains grown in [101], [110], and [103] directions. The method of claim 6,
The tin (II) oxide channel layer is a method of manufacturing a thin film transistor in which [101] and [110] peaks are combined in an XRD (X-ray diffraction) spectrum to appear as one peak. The method of claim 5,
[001] Peak in the XRD (X-ray diffraction) spectrum of the tin (II) oxide channel layer has a half width of 0.1 to 1 degrees. The method of claim 5,
The tin precursor is a tin (II)-organic compound or tin (IV)-organic compound thin film transistor manufacturing method. The method of claim 9,
The tin precursor as a ligand [((C ₁ -C ₅ )alkyl) _n silyl] _m amino group (n is 1, 2, or 3 and m is 1 or 2) a thin film transistor manufacturing method having at least one. The method of claim 10,
The ligand is [((C ₁ -C ₅ )alkyl) _n silyl] _m amino group (n is 3 and m is 2). The method of claim 5,
The tin precursor is (TMSA) ₂ Sn(II) (bis[bis(trimethylsilyl)amino]tin(II)) in a thin film transistor manufacturing method. The method of claim 5,
The heat treatment is a method of manufacturing a thin film transistor performed in a temperature range of more than 280 degrees and less than 400 degrees in an inert gas atmosphere. The method of claim 5,
The tin precursor pressure dosing step and the tin precursor purge step constitute a tin precursor subcycle,
Before the step of supplying the oxidizing agent, a method of manufacturing a thin film transistor in which the tin precursor subcycle is performed multiple times. The method of claim 5,
The oxidizing agent supply step
A method of manufacturing a thin film transistor in which the oxidizing agent is supplied while the outlet of the chamber is closed and the reaction pressure in the chamber is increased. The method of claim 15,
The oxidant pressure dosing step and the oxidant purge step constitute an oxidant subcycle,
The unit cycle is a thin film transistor manufacturing method comprising performing a plurality of times in succession the oxidizing agent sub-cycle. A polycrystalline thin film grown in the [001] direction preferentially, but includes all crystal grains grown in the [101], [110], and [103] directions in addition to the [001] direction, and in the XRD (X-ray diffraction) spectrum The [101] peak and the [110] peak are combined to form a single peak of a tin (II) oxide layer. delete

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