DE10049257B4 - Process for thin film production by means of atomic layer deposition - Google Patents

Abstract

A method of producing an alumina thin film using an atomic layer deposition (ALD) method comprising the steps of: injecting a first reactant containing a thin film forming species and a ligand into a reaction chamber including a substrate so that the first reactant is chemisorbed into the substrate, removing any first reactant physisorbed into the substrate merely by purging the reaction chamber with inert gas, forming a thin film in units of atomic layers by a chemical reaction between the thin film forming one An atomic species and a second reactant whose binding energy with respect to the thin-film forming atomic species is greater than the binding energy of the ligand with respect to the thin-film forming atomic species by injecting the second reactant into the reaction chamber and removing the ligand without generating by-products, e.g. nd - removing any physisorbed second reactant by purging the chamber with inert gas after the step of injecting the second reactant, - wherein the first reactant is Al (CH3) 3 and the second reactant is an oxidizing agent selected from the group consisting of which consists of O3, O2 plasma and N2O plasma.

Description

The invention relates to a method of thin film formation using an atomic layer deposition (ALD) method.

In general, a thin film, called a thin film or thin film for short, e.g. Example, as a dielectric of a semiconductor device, transparent conductor of a liquid crystal display or protective layer of an electroluminescent Dünnfilmanzeige used. A thin film may be formed by a sol-gel method, a sputtering method, an electroplating method, a vapor deposition method, a chemical vapor deposition (CVD) method, or an atomic layer deposition (ALD) method.

Among these methods, better step coverage can be obtained by an ALD method than by a CVD method, and it is possible with the ALD method to perform a low temperature process. In an ALD process, the thin film is formed by decomposing a reactant not by pyrolysis but by chemical exchange with periodic supply of the respective reactants. Hereinafter, a method of forming an aluminum oxide film which can be used as a dielectric film of a semiconductor device using a conventional ALD method will be described in detail. 1 FIG. 10 is a flowchart of the process of producing an alumina film using a conventional ALD method. FIG. The 2A to 2D describe the reaction mechanism during the production of the aluminum oxide film by the method of 1 ,

Specifically, a first reactant A, namely trimethylaluminum (Al (CH ₃ ) ₃ , "TMA") consisting of aluminum a ₁ and a methyl ligand a _2, is injected into a reaction chamber (not shown) into which a silicon substrate has been introduced ( step 1 ). The reaction chamber is cleaned by injecting an inert gas from a physisorbed first reactant A (step 3 ). Thus, only the first reactant A chemisorbed into a substrate S remains bound to the substrate S, as in FIG 2A shown.

A second reactant B, namely water vapor consisting of oxygen b ₁ and a hydrogen radical b ₂ , is injected into a reaction chamber containing the substrate S into which the first reactant A is chemisorbed (step 5 ). Thereby, the second reactant B is chemisorbed in the first reactant A, as in 2 B shown.

The hydrogen radical b _{2 of} the chemisorbed second reactant B migrates to the methyl ligand a _{2 of} the first reactant A and the methyl ligand is separated from the first reactant A as in 2C shown. As in the chemical formula 1 and below 2D The hydrogen radical b _{2 of} the second reactant B reacts with the methyl ligand a _{2 of} the separated first reactant A to form a volatile vapor phase material D consisting of CH ₄ . By the reaction between aluminum a _{1 of} the first reactant A and hydrogen b _{1 of} the second reactant B, an aluminum oxide film C is formed on the substrate S. 2Al (CH ₃ ) ₃ + 3H ₂ O → Al ₂ O ₃ + 6CH ₄ (1)

The volatile gas phase material D formed from CH ₄ and the unreacted vapor are removed by appropriately cleaning the reaction chamber by injecting an inert gas (step 7 ). It is checked whether the aluminum oxide film is formed with a suitable thickness (step 9 ), and steps 1 to 7 are cyclically repeated if necessary.

In a conventional ALD method, since the methyl ligand is removed by the movement of the hydrogen radical b ₂ , a sub-reaction that generates an OH radical that remains in accordance with the movement of the hydrogen radical b _{2 occurs} , as in Chemical Formula 2 described. Al (CH ₃ ) ₃ + 3H ₂ O → Al (OH) ₃ + 3CH ₄ (2)

When the subreaction occurs, unwanted impurities such as Al (OH) _{3 are incorporated} into the alumina film C. When incorporating impurities such as Al (OH) ₃ , it is not possible to achieve desired thin film characteristics. particularly effective when an aluminum oxide film with Al (OH) ₃ is used as a dielectric film of a semiconductor device, the aluminum oxide film having Al (OH) ₃ as a capture site for electrons or as a leakage current location, whereby the properties of the dielectric film are deteriorated.

In the journal article H. Kumagai et. al., Comparative Study of Al ₂ O ₃ Optical Crystalline Thin Films Grown by Vapor Combinations of Al (CH ₃ ) ₃ / N ₂ O and Al (CH ₃ ) ₃ / H ₂ O ₂ , Jpn. J. Appl. Phys. Vol. 32 (1993), Part 1, No. 12B, page 6137 discloses a method for producing high optical quality crystalline Al ₂ O ₃ thin films by means of a thermal CVD process using N ₂ O and H ₂ O ₂ as the oxidizing agent , where as aluminum vapor source high purity TMA is used. In this case, TMA and N ₂ O are alternately introduced into an associated CVD reactor, and for a corresponding surface reaction process then H ₂ O _{2 is used} instead of N ₂ O.

In the published patent application WO 99/29924 A1 discloses a process for coating surfaces and in particular inner surfaces of, for example, tubes by atomic layer epitaxy (ALE), in which the surface to be coated in an ALE reactor is exposed to at least two reactants involved, which are alternately and separated from each other by inert gas purges into the reactor be introduced. For coating with an Al ₂ O ₃ film z. As TMA and water used as reactants. A similar ALD deposition process, in which alternately different reactants separated by intermediate inert gas flushes are introduced into an ALD reactor, z. As the reactants TMA and water and argon as an inert gas, is in the published patent application JP 11-269652 A disclosed.

In the journal article Y. Kim et al., Substrate dependence on the optical properties of Al ₂ O ₃ films grown by atomic layer deposition, Appl. Phys. Lett. 71 (25), 1997, page 3604 is reported on the dependence of optical properties of ALD grown Al ₂ O ₃ thin films from the substrate. The thin films were deposited in a vertical hot wall reactor with a spray head and resistively heated substrate support using TMA, Al (CH ₃ ) ₃ and vaporous distilled water as chemical precursors at a substrate temperature of 370 ° C after previously etching the silicon substrate by wet etching and Hydrofluoric acid treatment was purified.

The layer growth process was carried out in several cycles, each purged with argon.

The invention is based on the technical problem of providing a method of the type mentioned, with which by means of an ALD technique, a highly pure thin film can be produced, which is largely free of undesirable impurities.

The invention solves this problem by providing a method having the features of claim 1, 3 or 10.

According to the invention, the ligand of the first reactant is separated from the second to the first reactant by the difference in binding energy without movement of a radical. A volatile vapor phase material is formed and expelled by the combination of ligands. Accordingly, a high-purity thin film can be obtained without interfering with unwanted by-products such as a hydroxide because impurities formed in the thin film by a sub-reaction can be reduced without the movement of the radical.

Advantageous developments of the invention are specified in the subclaims.

Advantageous embodiments of the invention described below and the conventional embodiment explained above for better understanding thereof are shown in the drawings, in which:

1 10 is a flowchart of the process of producing an alumina film using a conventional atomic layer deposition (ALD) process;

2A to 2D the reaction mechanism during the production of the aluminum oxide film of 1 .

3 1 schematically shows an apparatus for producing a thin film from an atomic layer by means of an ALD method according to the invention,

4A to 4D the reaction mechanism of a thin-film forming method using an ALD method according to a first embodiment of the invention;

5 FIG. 4 is a flowchart of the process for producing an alumina film according to the first embodiment of the invention; FIG.

6A to 6D the reaction mechanism for the production of the alumina film using the ALD method of 5 .

7 and 8th Graphs showing residual gas analysis (RGA) data when the aluminum oxide film is formed by the conventional technology or the first embodiment of the invention,

9 Fig. 12 is a graph showing the thickness of the alumina film as a function of the number of cycles when the alumina film is formed by the conventional technology and the first embodiment of the invention;

10 FIG. 12 is a graph showing strain hysteresis versus temperature of alumina films formed by the conventional technology and the first embodiment of the invention. FIG.

11 FIG. 4 is a graph showing the percentage of thickness contraction versus annealing conditions of alumina films formed by the conventional technology and the first embodiment of the invention; FIG.

12 and 13 graphs showing the absorption constants and refractive indices of alumina films formed by the conventional technology and the first embodiment of the invention as a function of wavelength,

14 FIG. 4 is a graph showing the wet etching rates of alumina films formed by the conventional technology and the first embodiment of the present invention as a function of the temperature of a post-annealing and the atmosphere gas; FIG.

15 10 is a sectional view showing the structure of a capacitor of a semiconductor device using a dielectric film formed by the first embodiment of the invention;

16 10 is a sectional view showing the structure of a transistor of a semiconductor device using a dielectric film formed by the first embodiment of the invention;

17 FIG. 4 is a graph showing the leakage current characteristics of a conventional capacitor and an SIS capacitor using a dielectric film formed by the first embodiment of the present invention as a function of applied voltage; FIG.

18 FIG. 12 is a graph showing the threshold voltage of the SIS capacitor using a dielectric film formed by the first embodiment of the present invention depending on the thickness of an equivalent oxide film. FIG.

19 12 is a graph showing the leakage current characteristic of an MIS capacitor to which a dielectric film formed by the first embodiment of the invention is applied depending on the applied voltage;

20 FIG. 4 is a graph comparing the leakage current characteristic of the MIS capacitor using a dielectric film formed by the first embodiment of the present invention with the leakage current characteristic of a conventional capacitor. FIG.

21A and 21B graphs showing the leakage current characteristic versus the applied voltage when the aluminum oxide films according to the conventional technology and the first embodiment of the invention are used as cover films of an MIM capacitor;

22 FIG. 3 is a flow chart of a second embodiment of the method of forming a thin film using ALD method of the present invention; FIG.

23A to 23D a combination relationship between reactants adsorbed on a substrate when an aluminum oxide film is formed by a thin film forming method using an ALD method according to the second embodiment of the invention,

24 an X-ray photoelectron spectroscopy (XPS) graphic of the aluminum oxide film formed by a conventional ALD method,

25A and 25B Graphs showing the leakage current characteristic of alumina films, which were prepared by the conventional method and by the second embodiment of the invention,

26 FIG. 4 is a flowchart of a thin film formation method using an ALD method according to a third embodiment of the invention; FIG.

27 FIG. 3 is a timing chart showing the supply of reactants during the formation of a thin film using an ALD method according to the third embodiment of the invention; FIG.

28 Fig. 12 is a graph showing the thickness of an alumina film produced by the method of forming an atomic layer thin film according to the third embodiment of the invention, depending on the number of repetitions of the process steps;

29 Fig. 12 is a graph showing the uniformity of an alumina film produced by the method of forming a thin film of an atomic layer according to the third embodiment of the invention;

30A and 30B graphs for analyzing the aluminum peak values of alumina films using XPS produced by the conventional technology and the method for producing an atomic layer thin film according to the third embodiment of the invention, respectively;

31A and 31B Graphs for analyzing the carbon peaks of alumina films using XPS, which were prepared by the conventional technology or the method for producing a thin film using an ALD method according to the third embodiment of the invention, and

32 a flowchart of a method for producing a thin film of an atomic layer according to a fourth embodiment of the invention.

The invention will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown without being limited thereto. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. It should also be understood that when a layer is referred to as being "on top" of another layer or substrate, it may be directly on top of the other layer or substrate, or intervening layers may be present. The same reference numerals in different representations represent functionally similar elements which, therefore, generally need only be described once.

3 FIG. 5 illustrates an apparatus for forming a thin film from an atomic layer using an atomic layer deposition (ALD) method of the invention. The apparatus includes a reaction chamber 11 , which can be heated by an external heater (not shown), a holder 13 at the bottom of the reaction chamber 11 is installed on it a substrate 15 to hold, for example, a silicon substrate, a shower head 17 that over the holder 13 is installed so that the reaction gas enters the reaction chamber 11 can be injected, as well as a vacuum pump 19 connected to the reaction chamber 11 connected to the pressure inside the reaction chamber 11 to control.

With the shower head 17 two gas inlets A and B are connected, which are separated from each other. In the shower head 17 For example, a first reactant, an inert gas, a second reactant, and a third reactant may be injected. The first reactant is a metallic reactant. The inert gas is nitrogen gas or argon gas. The second reactant is water vapor or an oxidizing gas that does not contain hydroxide, for example, N ₂ O, O ₂ , O _3, or CO ₂ gas. The third reactant is water vapor or a material containing an oxygen radical as the activated oxidizing agent, such as ozone, O ₂ plasma or N ₂ O plasma. In 3 For example, the second reactant and the third reactant are installed separately, but they may be installed together.

The first reactant and the inert gas are introduced through the gas inlet A into the reaction chamber 11 injected. The second reactant and the third reactant are introduced into the reaction chamber through the gas inlet B 11 injected. The first reactant, the second reactant and the third reactant have different gas inlets to prevent them from reacting with each other inside a gas inlet. Injecting the first reactant and the inert gas into the reaction chamber 11 is controlled by a first valve V1 and a second valve V2. Injecting the second reactant and the third reactant into the reaction chamber 11 is controlled by a third valve V3 and a fourth valve V4.

Now, various embodiments of the method of forming a thin film from an atomic layer using the apparatus described above will be described.

First embodiment

The 4A to 4D illustrate the reaction mechanism of a method of forming a thin film using an ALD method according to a first embodiment of the present invention. After chemisorption of a first reactant A consisting of an atom a ₁ forming a thin film and a ligand a ₂ into a substrate 15 , for example, a silicon substrate, by injecting the first reactant A into the reaction chamber 11 provided with the substrate, the physisorbed first reactant A is removed by cleaning the reaction chamber by injecting the inert gas ( 4A ).

A second reactant B is added to the reaction chamber 11 containing the substrate in which the first reactant A is adsorbed. As a result, the second reactant B is chemisorbed in the first reactant A. As the second reactant B, an imperfect material is used which reacts actively with the first reactant A. Specifically, as the second reactant B, a material is used in which the binding energy between the second reactant B and the thin film forming atom a _{1 of} the first reactant A is greater than the binding energy between the thin film forming atom a _{1 of} the first reactant A and the ligand a ₂ ( 4B ).

Since the binding energy between the second reactant B and the thin film forming atom a _{1 of} the first reactant A is greater than the binding energy between the thin film forming atom a _{1 of} the first reactant A and the ligand a ₂ , the second reactant B combines with the thin film-forming atom a _{1 of} the first real state A, and the ligand a ₂ is separated from the first reactant A ( 4C ).

Since the ligand a ₂ separated from the first reactant A is unstable, a highly volatile gas phase material D is formed by combining the ligands a ₂ . A reaction between the thin film-forming atom a _{1 of} the first reactant A and the second reactant B occurs on the substrate 15 a thin film C is formed in units of atomic layers. The volatile gas phase material D is removed by purging with the inert gas ( 4D ).

As an example, consider a case where the method of forming a thin film using a difference in binding energy included in the 4A to 4D described is used to produce an aluminum oxide film.

5 Fig. 10 is a flowchart of the process of producing an alumina film according to a first embodiment of the invention. The 6A to 6D illustrate the reaction mechanism when the aluminum oxide film using the ALD method of 5 is formed. The first reactant A, such as trimethylaluminum (Al (CH ₃ ) ₃ ), TMA), consisting of thin film-forming aluminum a ₁ and a methyl ligand a ₂ , is introduced into the reaction chamber 11 injected with the substrate 15 , for example, a silicon substrate, is equipped (step 101 ). The physically adsorbed TMA is removed by purging with inert gas (step 103 ). This leaves only TMA in the substrate 15 is chemisorbed, as in 6A shown.

The second reactant, such as ozone B, which is an oxidizing agent, enters the reaction chamber 11 in which the TMA is adsorbed (step 105 ). This ozone B is chemisorbed into the aluminum a _{1 of} the TMA, as in 6B shown.

Ozone B is an imperfect material that actively reacts with TMA. The binding energy between ozone B and the aluminum a _{1 of} the TMA is about 540 kJ / mol, which is greater than the binding energy between the aluminum a _{1 of} the TMA and the methyl ligand a ₂ (for example, the Al-C bond energy), which is 255 kJ / mol. Since the binding energy between ozone B and is larger than the bond energy between the thin film-forming aluminum a ₁ of the TMA and the methylene ligand A ₂ the thin film-forming aluminum a ₁ of the TMA, the Methylligand is separated a ₂ of the TMA, as described in 6C shown.

In addition, since the methyl ligand a ₂ separated from the TMA is unstable, the compound of the methyl ligands a _{2 forms} a highly volatile gas phase material D of C ₂ H ₆ as described in U.S. Pat 6D shown. The reaction between the thin film-forming aluminum a _{1 of} the TMA and ozone B occurs on the substrate 15 an aluminum oxide film C is formed in units of atomic layers as shown in Chemical Formula 3. 2Al (CH _{3) 3} + O ₃ → Al ₂ O ₃ + 3C ₂ H ₆ (3)

The volatile gas phase material D formed from C ₂ H ₆ and the unreacted methyl ligands a ₂ are removed by rinsing the reaction chamber with the inert gas for a second time (step 107 ). It is checked whether the aluminum oxide film already has a suitable thickness (step 109 ), and the steps 101 to 107 are cyclically repeated if necessary.

In the present embodiment, ozone is used as the second reactant. However, ozone can be more strongly activated by using ultraviolet (UV) rays or, instead of ozone, an O ₂ plasma or an N ₂ O plasma can be used as the activated oxidizing agent as shown in Chemical Formula 4. TMA + O ₃ (activated) ⇒ 4Al (CH ₃ ) ₃ + 3O ₂ → 2Al ₂ O ₃ + 6C ₂ H ₆ (4)

The 7 and 8th Fig. 15 are graphs showing residual gas analysis (RGA) data when an aluminum oxide film is formed by the conventional technology and by the first embodiment of the present invention, respectively. In the 7 and 8th For example, the aluminum oxide film is formed in the arrow marked areas.

Since the shape of the ligand removed varies depending on the mechanism with which the second reactant B reacts with the first reactant A as mentioned above, the material generated during a process varies. Namely, when the TMA and water vapor (H ₂ O) are used as the first reactant A and the second reactant B, respectively, as in the case of 7 , CH ₃ ⁺ and CH ₄ ⁺ , which are formed by taking up a hydrogen radical from the water vapor (H ₂ O), are detected as the major by-products. When TMA and ozone are used as the first reactant A and the second reactant B, respectively, as it is 8th If this is the case, CH ₃ ligands are removed, and thus C ₂ H ₅ ⁺ or C ₂ H ₆ ^{+ is} detected as the major by-product.

9 FIG. 12 is a graph showing the thickness of the alumina film as a function of the number of cycles when the Alumina film is formed by the conventional technology and the first embodiment of the invention. The thickness of an applied thin film is determined by the number of supply cycles of each reactant, since an atomic layer deposition (ALD) process is a surface control process. Namely, when the thickness increases linearly with the number of cycles, it means that the thin film is formed by an ALD method. Out 9 It can be seen that the thickness actually increases linearly in the conventional technology and in the present invention, and thus the thin film is formed by an ALD method.

The difference in latent cycles between the conventional technology (marked with)) using water vapor as the second reactant B and the invention (marked with)) using ozone as the second reactant B is shown. Namely, in the invention (marked with o), the thin film is deposited from an initial cycle without a latent cycle. However, in the conventional technology (marked with •), the thin film is deposited after lapse of a latent period of 12 cycles. From this, it can be seen that the aluminum oxide film formed in the invention is more stably formed because the thin film is formed by a heterogeneous reaction.

10 Fig. 12 is a graph showing the stress hysteresis depending on the temperature of alumina films formed by the conventional technology and the first embodiment of the invention.

Specifically, in the stress hysteresis (marked with □) of the conventional alumina film formed by using TMA as the first reactant A and using water vapor as the second reactant B, the kind of stress at 450 ° C changes from tensile stress to compressive stress. Meanwhile, in the stress hysteresis (marked with)) of the alumina film of the present invention, by using TMA and ozone as the first reactant A and the second reactant B, respectively, the kind of stress is tensile stress in the entire temperature range, that is, the stress mode does not change. Accordingly, it should be noted that the film formed according to the invention is more stable to heat.

11 Fig. 12 is a graph showing the percentage of thickness contraction versus the annealing conditions of the alumina films formed by the conventional technology and the first embodiment of the present invention. On the x-axis, N450, N750 and N830 are samples that have been post-annealed in nitrogen atmospheres at 450 ° C, 750 ° C and 830 ° C, respectively. Analogously, O450, O750 and O830 refer to samples that have been post-annealed in oxygen atmospheres at 450 ° C, 750 ° C and 830 ° C, respectively. RTO is a sample that has undergone rapid thermal oxidation at 850 ° C. It can be seen that the percentage of thickness contraction (the rate of decrease in thickness) as a function of temperature and gas conditions of post-annealing in the alumina films does not vary significantly depending on whether the films were formed by the conventional technology or the first embodiment of the present invention.

The 12 and 13 Fig. 11 are graphs showing the absorption constants and refractive indices of the alumina films formed by the conventional technology and the first embodiment of the present invention as a function of wavelength. The absorption constants of the alumina films formed by the conventional technology and the first embodiment of the present invention are less than 0.005 for wavelengths from 180 nm to 900 nm as shown in FIG 12 shown. That is, the alumina films formed by the conventional technology and the first embodiment of the present invention have excellent transparency. The refractive indices of the alumina films formed by the conventional technology and the first embodiment of the present invention do not vary significantly for wavelengths from 180 nm to 900 nm, as in FIG 13 shown.

14 Fig. 12 is a graph showing the wet etching rates of alumina films formed by the conventional technology and the first embodiment of the present invention depending on the temperature of the post-annealing and the atmosphere gas. On the x-axis as-dep is a sample which was not tempered after application to the substrate. N450, N750 and N830 are samples post-annealed in nitrogen atmospheres at 450 ° C, 750 ° C and 830 ° C. O450, O750 and O830 are samples that have been post-annealed in oxygen atmospheres at 450 ° C, 750 ° C and 830 ° C. RTP is a sample that undergoes rapid thermal oxidation at 850 ° C in an oxygen atmosphere. The y-axis denotes etch rates when the respective samples were wet etched by an HF solution of 200: 1.

As in 14 In the alumina films formed by the conventional technology and the first embodiment of the present invention, the wet etching rates decrease with increasing annealing temperatures regardless of annealing conditions. In particular, the Etch rate rapidly reduced to 2 Å / min (= 0.2 nm / min) to 3 Å / min (= 0.3 nm / min), when the post-annealing is performed at temperatures greater than 800 ° C. In addition, the etching rate of the alumina film according to the first embodiment of the present invention is about 30% lower than the etching rate of the alumina film according to the conventional technology when the post-annealing is performed at temperatures lower than 800 ° C. From this, it can be seen that the oxide film is chemically more stable when ozone is used as the oxidizing gas than in the case where water vapor is used as the oxidizing gas.

Now, a case will be described in which the aluminum oxide film formed by the first embodiment of the present invention is used for a semiconductor device.

15 Fig. 10 is a sectional view showing the structure of a capacitor of a semiconductor device using a dielectric film formed by the first embodiment of the present invention. The capacitor of the semiconductor device for which the dielectric film formed by the first embodiment of the present invention is used includes a lower electrode 205 on a substrate 201 , For example, a silicon substrate is formed, a dielectric film 207 and an upper electrode 209 , In 15 denote the reference numerals 203 and 211 a dielectric intermediate film or a top layer formed on the upper electrode of the capacitor.

The following is a capacitor where the top electrode 209 and the lower electrode 205 are formed of an impurity doped polysilicon film and the dielectric film 207 is formed of an alumina film formed by the first embodiment of the present invention, referred to as a "SIS" capacitor. A capacitor where the lower electrode 205 is formed of an impurity doped polysilicon film, the dielectric film 207 is formed from an aluminum oxide film formed by the first embodiment of the present invention, and the upper electrode 209 is formed of a TiN film is referred to as "MIS" capacitor. A capacitor in which the upper electrode 209 and the lower electrode 205 are formed of noble metals of the platinum group, such as Pt and Ru, and the dielectric film 207 is formed of an insulating film such as a TaO film or BST (BaSrTiO ₃ ) is referred to as "MIM" capacitor.

16 Fig. 10 is a sectional view showing the structure of a transistor of a semiconductor device to which a dielectric film formed by the first embodiment of the present invention is applied. The semiconductor device for which the dielectric film according to the first embodiment of the present invention is used includes a silicon substrate doped with impurities such as phosphorus, arsenic or boron 301 acting as the first electrode, a gate insulating film 305 which acts as a dielectric film, and a gate electrode 307 which acts as a second electrode. In 16 denotes the reference numeral 303 Source and drain regions that are impurity doped regions.

When the structure of the transistor of the semiconductor device according to the invention is compared with the structure of the capacitor of the semiconductor device according to the invention, the silicon substrate correspond 301 and the gate electrode 307 the lower electrode or the upper electrode. The gate insulation film 305 corresponds to the dielectric film of the capacitor.

The insulating properties of the dielectric film will now be described with reference to the structure of the capacitor for the sake of simplicity, but the same thing also applies to the transistor.

17 FIG. 15 is a graph illustrating the leakage current characteristics of a conventional capacitor and an SIS capacitor to which the dielectric film formed by the first embodiment of the present invention is applied depending on the applied voltage.

Specifically, the SIS capacitor of the present invention (marked with o) is the same as the conventional capacitor (marked with •) except that the method of forming the dielectric film of the SIS capacitor is different from the method of forming the dielectric film of the SIS capacitor different from conventional capacitor. As in 17 1, the SIS capacitor (o) according to the invention shows a threshold voltage which is greater than the threshold voltage of the conventional capacitor (•) at a leakage current density which can be allowed in a capacitor of a conventional semiconductor device, namely 1 × 10 ^-7 A / cm ² . Therefore, since the thickness of the dielectric film can be reduced at a certain leakage current value in the SIS capacitor (o) of the present invention, the SIS capacitor (o) of the present invention is advantageous for increasing the degree of integration of the semiconductor device.

18 Fig. 12 is a graph showing the threshold voltage of the SIS capacitor using the dielectric film formed by the first embodiment of the present invention, depending on the thickness of an equivalent oxide film. Since the SIS capacitor according to the invention shows stable insulation properties until the thickness of the equivalent oxide film is 3.5 nm, the threshold voltage is not significantly reduced. If the thickness of the equivalent oxide film is less than 3.5 nm, the threshold voltage is rapidly reduced, and thus the insulating properties deteriorate.

19 Fig. 12 is a graph showing the leakage current characteristic of an MIS capacitor to which the dielectric film formed by the first embodiment of the present invention has been applied in response to applied voltages. As a common reference value, at a leakage current density of 1 × 10 ^-7 A / cm ² and a voltage of 1.2 V, the thickness of the equivalent oxide film in the case of the MIS capacitor of the present invention may be 2.65 nm. If the thickness of the equivalent oxide film is reduced, this is very advantageous for increasing the integration density of the semiconductor device.

20 Fig. 12 is a graph for comparing the leakage current characteristic of the MIS capacitor for which the dielectric film formed by the first embodiment of the present invention is used with the leakage current characteristic of the conventional capacitor. The conventional capacitor is the same as the MIS capacitor of the present invention except that the dielectric film of the conventional capacitor is different from the dielectric film of the MIS capacitor. As in 20 1, an applied voltage in the MIS capacitor using the alumina film according to the first embodiment of the present invention, at a leakage current value of 1fA per cell, is larger than an applied voltage in the conventional capacitor in which a TaO film or a NO Film is used as a dielectric film. That is, the leakage current characteristic of the MIS capacitor of the present invention is better than the leakage current characteristic of the conventional capacitor even in a thin equivalent oxide film. In 20 numbers in brackets denote the thicknesses of the dielectric films.

bezeichnet einen Fall, in dem der als Deckfilm gebildete Aluminiumoxidfilm bei 400°C mit Wasserstoff getempert wird. In 21B bezeichnet ”•” einen Fall, in dem der Aluminiumoxidfilm gemäß der ersten erfindungsgemäßen Ausführungsform gebildet wird, um als Deckfilm zu dienen.

bezeichnet einen Fall, in dem der als Deckfilm gebildete Aluminiumoxidfilm bei 400°C mit Wasserstoff getempert wurde.

bezeichnet einen Fall, in dem der als Deckfilm gebildet Aluminiumoxidfilm bei 700°C mit Stickstoff getempert wurde.The 21A and 21B Fig. 10 is graphs showing leakage current characteristics depending on the applied voltage when the aluminum oxide films according to the conventional technology and the first embodiment of the present invention are used as cover films of an MIM capacitor. In the 21A and 21B "∎" indicates the MIM capacitor when the cover film is not used. In 21A "" indicates a case where the aluminum oxide film is formed according to the conventional technology to serve as a cover film.

denotes a case where the aluminum oxide film formed as a cover film is annealed with hydrogen at 400 ° C. In 21B "" indicates a case where the aluminum oxide film according to the first embodiment of the present invention is formed to serve as a cover film.

denotes a case where the aluminum oxide film formed as a cover film was annealed with hydrogen at 400 ° C.

denotes a case where the aluminum oxide film formed as a cover film was annealed with nitrogen at 700 ° C.

In general, when the MIM capacitor is used for a semiconductor device, the dielectric film deteriorates during the hydrogen annealing process performed in a subsequent alloying process. Accordingly, the cover film, which acts as a hydrogen barrier, is formed on the MIM capacitor. As in 21A As shown in FIG. 4, the leakage current characteristic does not deteriorate when the aluminum oxide film formed by the first embodiment of the present invention is used as the cover film because the barrier property is excellent after performing the subsequent hydrogen annealing processes. However, when the aluminum oxide film formed by the conventional technology is used as a cover film as in 21B Hydrogen from the water vapor and an OH ligand degrade the leakage current characteristic of the MIM capacitor during the deposition process.

Second embodiment

22 FIG. 10 is a flowchart of a second embodiment of the thin film forming method of the present invention using an ALD method. FIG. It becomes a final treatment for linking the unpaired bond of the substrate 15 with oxygen by means of oxygen rinsing of the substrate ( 15 from 3 ), for example of the silicon substrate, with oxidizing gas (step 21 ). That is, in any places where oxygen to the substrate 15 Oxygen can be bound by oxygen scavenging of the substrate ( 15 from 3 ), for example, the silicon substrate, bound with oxidizing gas. The unpaired bond can be oxygenated, that is, oxygen can be bound to the substrate not only by performing oxygen scavenging, but also by performing ozone scavenging and forming a silica film at any available location. Alternatively, it is possible to oxygen purge the substrate 15 not to perform.

After loading the reaction chamber ( 11 from 3 ) with the substrate 15 becomes the process temperature of the reaction chamber 11 between 100 ° C and 400 ° C, preferably between 300 ° C and 350 ° C, and the process pressure of reaction chamber 11 is maintained between 1 mTorr (= 0.1333 Pa) and 10,000 mTorr (= 1333.22 Pa) using a heater (not shown) (step 23 ). The process temperature and pressure are kept in the following steps, but they can be changed as needed.

The first reactant, such as trimethylaluminum (Al (CH ₃ ) ₃ ; TMA), passes through the gas inlet A and the showerhead 17 for a sufficiently long time in the reaction chamber 11 to cover the surface of the substrate, for example, for 1 ms to 10 s, by opening the first valve V1 while maintaining the process temperature and pressure (step 25 ). This chemisorbs the first reactant into the oxygen-purged silicon substrate.

The reaction chamber 11 is cleaned with inert gas such as argon for 0.1 second to 100 seconds by selectively opening the second valve V2 while maintaining the process temperature and pressure (step 27 ). This removes the first reactant, which is only physically on the substrate 15 is deposited.

The second reactant, for example oxidizing gas containing no hydroxide, passes through the showerhead 17 in the reaction chamber 11 is injected by the third valve V3 is opened, while the process temperature and the process pressure are maintained (step 29 ). N ₂ O, O ₂ , O ₃ or CO ₂ gas can be used as the second reactant. As a result, the chemisorbed first reactant reacts with the second reactant. Accordingly, the first reactant is chemically exchanged to form a metal-oxygen atomic layer film. The second reactant does not react completely with the first reactant. However, it is possible to form the atomic metal-oxygen layer without generating a hydroxide in a metal oxide film as described later.

Excess reactants are removed by passing the reaction chamber 11 purging with inert gas a second time for 0.1 second to 100 seconds while maintaining the process temperature and pressure (step 31 ).

The third reactant, for example an oxide such as water vapor, passes through the showerhead 17 for a sufficiently long time in the reaction chamber 11 injected to cover the surface of the substrate, for example, for 1 ms to 10 s, by opening a fourth valve V4 (step 33 ). As a result, the first reactant that did not react with the second reactant reacts with the third reactant because the third reactant reacts more actively with the first reactant than does the second reactant, and is chemically exchanged to further produce the film from an atomic one Metal-oxygen layer contribute. At this time, a metal oxide film is formed in units of atomic layers in which the generation of a hydroxide is prevented because the available amount of the first reactant is reduced by previously reacting the second reactant containing no hydroxide with the first reactant ,

In the present embodiment, an aluminum oxide film (Al ₂ O ₃ ) is an example of the metal oxide film. However, other examples of metal oxide films that can be formed according to the invention include a TiO ₂ film, a ZrO ₂ film, an HfO ₂ film, a Ta ₂ O ₆ film, an Nb ₂ O ₅ film CeO ₂ film, Y ₂ O ₃ film, SiO ₂ film, In ₂ O ₃ film, RuO ₂ film, IrO ₂ film, SrTiO ₃ film, PbTiO ₃ film , a SrRuO ₃ film, a CaRuO ₃ film, a (Ba, Sr) TiO ₃ film, a Pb (Zr, Ti) O ₃ film, a (Pb, La) (Zr, Ti) O ₃ - Film, a (Sr, Ca) RuO ₃ film, a (Ba, Sr) RuO ₃ film, a Sn doped In ₂ O ₃ (ITO) film and a Zr doped In ₂ O ₃ film.

Then, a cycle is completed in which the metal oxide film in units of atomic layers to remove the unnecessary reactants by purging the reaction chamber 11 with inert gas for 0.1 second to 100 seconds while maintaining the process temperature and pressure (step 35 ). It is highly possible to prevent the third reactant from reacting with the first reactant by further, after the third purge of the reaction chamber, performing a step of injecting and purging the second reactant which does not contain hydroxide.

Then, it is checked whether the thickness of the metal oxide film formed on the substrate is as desired, for example, between 1 nm and 100 nm (step 37 ). When the thickness of the metal oxide film is as desired, the step of forming the metal oxide film is terminated. If the metal oxide film is not thick enough, the steps from the step of injecting the first reactant into the reaction chamber until the step of third purging the reaction chamber (step 35 ) cyclically repeated.

The 23A to 23D illustrate the bonding relationship between reactants adsorbed on a substrate when the aluminum oxide film is formed by a thin film forming method using an ALD method according to a second embodiment of the present invention. The substrate 15 For example, the silicon substrate is purged with oxygen, causing unpaired binding of the substrate 15 With Oxygen is connected as in 23A shown. This means, therefore, that in any places where oxygen to the substrate 15 Oxygen can be bound to the surface of the substrate, as in 23A shown. It is possible the substrate 15 do not flush with oxygen if this is not necessary.

After injecting trimethylaluminum (Al (CH ₃ ) ₃ ), which is the first reactant, into the reaction chamber, whose process temperature is maintained between 100 ° C and 400 ° C and its process pressure is between 1 mTorr (= 0.1333 Pa) and 10,000 mTorr (= 1333.22 Pa), the reaction chamber is purged with argon gas. This leaves only the first reactant which is chemisorbed into the oxygen scavenged substrate, as in 23B shown. Namely, various forms of bonds such as Si-O, Si-O-CH ₃ and Si-O-Al-CH _{3 are} formed on the silicon substrate.

The second reactant, which does not contain any hydroxide, such as N ₂ O, O ₂ , O ₃ or CO ₂ , is introduced into the reaction chamber 11 injected. For example, when N ₂ O is used as the second reactant, the reaction continues as follows: 3Al (CH ₃ ) ₃ + 3N ₂ O → Al ₂ O ₃ + Al (CH ₃ ) ₃ + 3C ₂ H ₆ + 3N ₂ ↑ (5)

As shown in Chemical Formula 5, when N ₂ O containing no hydroxide is injected into trimethylaluminum, trimethylaluminum is consumed and Al ₂ O _{3 is} formed. That is, the chemisorbed first reactant reacts with the second reactant. Accordingly, the first reactant is chemically exchanged to further contribute to the formation of the film of the atomic metal-oxygen layer, as in 23C shown. Thus, Si-O-Al-O bonds are formed on the silicon substrate.

After injecting the third reactant, such as water vapor, into the reaction chamber, the reaction chamber is purged with argon gas. As a result, the first reactant, which did not react with the second reactant, reacts with the third reactant and is altered to form the atomic metal-oxygen layer, as in FIG 23D shown. At this time, the metal-oxide film is formed in units of atomic layers in which the generation of hydroxide is prevented, since the available amount of the first reactant by prior reacting the second reactant containing no hydroxide, with the first Reactants is reduced.

The manner in which the aluminum oxide film is formed in units of atomic layers in which the absolute amount of hydroxide is small will now be described in detail.

The inventors have discovered that the undesirable by-product Al (OH) ₃ is contained in the aluminum oxide film by the reaction represented by the hemic formula 2 when the aluminum oxide film is formed by a conventional ALD method. To search for by-product Al (OH) ₃ , the inventors carried out X-ray photoelectron spectroscopy (XPS) analysis of the alumina film formed by the conventional ALD method.

24 Fig. 10 is an X-ray photoelectron spectroscopy (XPS) curve of an aluminum oxide film formed by the conventional ALD method. In 24 the x-axis denotes the binding energy, and the y-axis denotes the electron count in arbitrary units.

It can be seen that the right side of the curve b is slightly wider than the right side of the curve a when the curves overlap by about 535.1 eV in the peak of the alumina film formed by the conventional ALD method , That is, the aluminum oxide film formed by the conventional ALD method shows a curve (b) having a width larger than a curve (a) of a pure alumina film, since in the film formed by the conventional method, Al (OH) ₃ is included.

It follows that the reaction represented by the chemical formula 2 produces a large amount of Al (OH) ₃ containing hydroxide when trimethylaluminum reacts directly with water vapor, as in the conventional technology. Therefore, the absolute amount of trimethylaluminum that reacts with water vapor must be reduced to reduce the amount of Al (OH) ₃ . In the present invention, since the absolute amount of trimethylaluminum is reduced by reacting trimethylaluminum with N ₂ O, which does not contain hydroxide, and then reacting the residual, unreacted trimethylaluminum with water vapor, the aluminum oxide film is reduced in units of atomic layers with a small amount absolute amount of hydroxide formed.

The 25A and 25B Fig. 10 are graphs showing the leakage current characteristic of alumina films produced by the conventional method and the second embodiment of the present invention, respectively. The leakage current characteristic is examined by attaching the aluminum oxide film to a capacitor. A polysilicon film becomes the lower electrode and the upper electrode of the capacitor used. In the 25A and 25B First curves a and c indicate measurement results of the amount of current for a cell flowing through a dielectric film when the lower electrode is connected to ground and a voltage between 0 V and 5 V is applied to the upper electrode. Second curves b and d denote measurement results of the amount of current for a cell flowing through the dielectric film under the same conditions under which the first measurement was performed after the first measurement. As in 25B is the leakage current at a given voltage, for example 2V, compared to the conventional case of 25A at the same voltage, when the aluminum oxide film formed by the present invention is used as the dielectric film, and the distance between the first curve and the second curve is small. Accordingly, it can be seen that the leakage current characteristic is improved by the present invention.

Third embodiment

26 FIG. 10 is a flowchart for a method of forming a thin film using an ALD method according to a third embodiment of the present invention. FIG. 27 Fig. 10 is a timing chart showing the supply of reactants during the formation of the thin film using the ALD method according to the third embodiment of the present invention. In the following description, the generation of an alumina film is taken as an example.

The unpaired bonding of the substrate, which may be a silicon substrate, is accomplished by oxygen or nitrogen purging of the substrate 15 saturated using an oxidizing or nitriding gas (step 41 ). That is, at any point where oxygen can be bound to the substrate, which may be a silicon substrate, oxygen or nitrogen purging of the substrate 15 oxygen bound to the substrate using an oxidizing or nitriding gas. The oxygen or nitrogen purge can not be performed only by using the atomic layer thin film forming apparatus as shown in FIG 3 is shown, but also using other devices. In addition, the unpaired bond can be linked to oxygen or nitrogen, that is, wherever oxygen or nitrogen can be bound to the substrate, this can be done not only by performing the oxygen or nitrogen purge, but also by performing ozone purification and Production of a silicon oxide film and a silicon nitride film take place. It is possible, if necessary, to dispense with the oxygen or nitrogen purge.

After equipping the reaction chamber 11 with the substrate 15 becomes the process temperature of the reaction chamber 11 maintained between 100 ° C and 400 ° C, preferably between 300 ° C and 350 ° C, and the process temperature of the reaction chamber 11 is using a heater (not shown) and a pump 19 between 1 mTorr (= 0.1333 Pa) and 10,000 mTorr (= 1333.22 Pa) (step 43 ). The process conditions are maintained in subsequent steps, but they can be changed as needed.

A first reactant, such as trimethylaluminum (Al (CH ₃ ) ₃ : TMA), passes through the gas inlet A and the showerhead 17 for a sufficiently long time in the reaction chamber 11 to cover the surface of the substrate, for example between 1 ms and 10 s, by opening the first valve V1 while maintaining the process conditions (step 45 ). This chemisorbs the first reactant into the oxygen or nitrogen purged silicon substrate.

The reaction chamber 11 is purged for a first time by an inert gas such as argon gas for 0.1 second to 100 seconds by selectively opening the second valve V2 while maintaining the process conditions (step 47 ). This removes any first reactant that is only physically on the substrate 15 is deposited.

A second reactant, for example oxidizing gas, which has excellent oxidation performance, such as water vapor, passes through the showerhead 17 by opening the third valve V3 in the reaction chamber 11 injected while the process conditions are maintained (step 49 ).

As a result, the chemisorbed first reactant reacts with the second reactant to form a thin film in units of atomic layers, that is, an alumina film is formed by chemical exchange. Namely, CH ₃ of TMA reacts with H of H ₂ O, forming CH ₄ which is removed. Al of TMA reacts with O of H ₂ O, forming Al ₂ O ₃ . Since the thin film is formed from the atomic layer at a temperature of 400 ° C or less, which is low, TMA is not completely decomposed. Accordingly, a large amount of impurities such as carbon or OH forms bonds in the aluminum oxide film.

Any second reactant that did not react with the first reactant and in the substrate 15 is merely physisorbed is, by a second flushing of the reaction chamber 11 with inert gas, such as argon gas, for 0.1 second to 100 seconds while maintaining the process conditions (step 51 ).

A third reactant for removing impurities and improving the stoichiometry of the thin film, for example, an oxidizing gas such as ozone, is injected into the reaction chamber through a fourth valve V4 and the showerhead for a sufficiently long time to cover the surface of the substrate on which the thin film is formed, for example, for 1 ms to 10 s (step 53 ). Thereby, it is possible to remove impurities, such as carbon or OH, bound to and contained in the thin film in units of atomic layers and to solve the problem that there is a shortage of oxygen in the aluminum oxide film. Accordingly, it is possible to obtain a thin film having an excellent stoichiometry.

A cycle during which the thin film is formed in units of atomic layers is replaced by a third cleaning operation of the reaction chamber 11 with an inert gas for 0.1 second to 100 seconds while maintaining the process conditions, thereby removing the unreacted, physisorbed third reactant (step 55 ).

It is checked whether the thin film in units of atomic layers formed on the substrate has the correct thickness, for example, between 1 nm and 100 nm (step 57 ). If the thickness of the thin film is correct, the process of forming the thin film is terminated. If the thin film is not sufficiently thick, the steps from the step of injecting the first reactant (step 45 ) until the step of the third rinse of the reaction chamber (step 55 ) cyclically repeated.

In the present embodiment, the alumina film is formed by using trimethylaluminum (Al (CH ₃ ) ₃ : TMA) as a first reactant, water vapor which is an oxide gas as a second reactant, and ozone gas to remove the impurities as a third reality. However, it is also possible to form a titanium nitride film using TiCl ₄ as a first reactant, NH ₃ as a second reactant, and nitrogen gas to remove impurities and to improve the stoichiometry of the thin film as a third reactant.

Further, according to the method of the present invention, for forming a thin film from an atomic layer, it is possible to form a monatomic oxide, a composite oxide, a monatomic nitride or a composite nitride instead of an aluminum oxide film or a titanium nitride film. TiO ₂ , Ta ₂ O ₅ , ZrO ₂ , HfO ₂ , Nb ₂ O ₅ , CeO ₂ , Y ₂ O ₃ , SiO ₂ , In ₂ O ₃ , RuO ₂ and IrO ₂ are examples of monatomic oxides. SrTiO ₃ , PbTiO ₃ , SrRuO ₃ , CaRuO ₃ , (Ba, Sr) TiO ₃ , Pb (Zr, Ti) O ₃ , (Pb, La) (Zr, Ti) O ₃ , (Sr, Ca) RuO ₃ , doped with Sn In ₂ O _3, Fe-doped In ₂ O ₃ and Zr-doped In ₂ O ₃ are examples of composite oxides. SiN, NbN, ZrN, TiN, TaN, Ya ₃ N _5, AlN, GaN, BN, and WN are examples of monatomic nitrides. WBN, WSiN, TiSiN, TaSiN, AlSiN and AlTiN are examples of composite nitrides.

A film formed by the method of forming a thin film using the ALD method of the present invention may be attached to semiconductor devices. For example, the thin film may be used as a gate oxide film, an electrode of a capacitor, an etch stopper film, a reaction preventing overcoat film, an antireflection film during a photolithography process, a barrier metal film, a selective deposition film, or a metallic gate electrode.

28 Fig. 12 is a graph showing the thickness of an alumina film produced by the method of forming a thin film of an atomic layer according to the third embodiment of the present invention, depending on how many times the steps of the process are repeated as a cycle. One cycle includes the steps of injecting the first reactant into the reaction chamber, purifying the reaction chamber from the physisorbed first reactant, injecting the second reactant into the reaction chamber, purifying the reaction chamber from the physisorbed second reactant, injecting the third reactant into the reaction vessel Reaction chamber and the cleaning of the reaction chamber of the physisorbed third reactant. As in 28 As shown in FIG. 2, the aluminum oxide film is easily formed by the atomic layer deposition method of the present invention, since the aluminum oxide film is grown at a thickness of 0.11 nm every cycle and the thickness of the aluminum oxide film linearly increases in proportion to the number of cycles.

29 Fig. 12 is a graph illustrating the uniformity of an alumina film produced by the method of forming an atomic layer thin film according to the third embodiment of the present invention. The x-axis indicates the locations of nine points: the center of an eight inch, four point substrate spaced 90 degrees apart on the circumference of a 1.75 inch diameter circle and another four points located on the Circumference of a circle with a diameter of 3.5 inches by 90 ° from each other. The y-axis denotes the Thickness of the alumina film. As in 29 The uniformity of the aluminum oxide film over the substrate of eight inches is excellent.

The 30A and 30B Fig. 15 are graphs for analyzing the aluminum peak values of alumina films using XPS produced by the conventional technology and the method for producing an atomic layer thin film according to the third embodiment of the present invention, respectively. Specifically, the x-axis denotes the binding energy, and the y-axis denotes the electron count. In the conventional aluminum oxide film, a large amount of Al-Al bonds occur as in 30A shown. In the alumina film of the present invention, almost no Al-Al bonds occur, and Al-O bonds are most conspicuous as in 30B shown. Accordingly, it can be seen that the stoichiometry of the aluminum oxide film of the present invention is excellent.

The 31A and 31B Fig. 15 are graphs for analyzing the carbon peaks of alumina films using XPS produced by the conventional thin-film forming technology using the ALD method according to the third embodiment of the present invention. Specifically, the x-axis denotes the binding energy, and the y-axis denotes the electron count. In the conventional aluminum oxide film, a carbon peak is shown as in FIG 31A , meaning that a large amount of carbon is contained in the alumina film. in the aluminum oxide film according to the invention is in 31B no carbon peak shown. Therefore, according to the invention, it is possible to obtain an alumina film in which impurities such as carbon are reduced.

Fourth embodiment

32 FIG. 10 is a flowchart for a method of forming a thin film of an atomic layer according to a fourth embodiment of the present invention. FIG. In 32 reference numerals identical to those of FIG 22 are, identical steps.

The fourth embodiment of the invention is a combination of the second embodiment and the third embodiment. Specifically, the fourth embodiment is the same as the second and third embodiments except that the reaction chamber is purged a fourth time (step 36b After a fourth reactant, for example an oxidizing gas such as ozone gas, to remove impurities and to improve the stoichiometry of the thin film through the third valve V3 and the showerhead 17 during a sufficiently long time to cover the surface of the substrate on which the thin film is formed, for example, for 1 ms to 10 seconds, is injected into the reaction chamber, as in the third embodiment (step 36a ) after the reaction chamber in the second embodiment has been cleaned a third time.

Thereby, it is possible to remove impurities such as bonded carbon or OH bonds contained in the metal oxide film in units of atomic layers, and to solve the problem that oxygen deficiency exists in the metal oxide film so as to allow an extremely pure thin film receive. That is, according to the invention, it is possible to obtain a thin film of desired quality and to minimize the density of impurities by increasing the likelihood that the major reactants will react with each other before or after they are injected. Thus, various impurities of the thin film can be removed from the main reactants, and the quality of the thin film can be improved by a complete reaction in the thin film formation method of the invention by atomic layer deposition (ALD).

As mentioned above, in the method of forming a thin film using an ALD method according to an embodiment of the present invention, the ligand of the first reactant A is separated due to a difference in the binding energy without causing a radical from the second reactant B to the first reactant A moves. By combining ligands, a volatile gas phase material is formed and the gas phase material is removed by rinsing. As a result, with the method of forming a thin film according to the present invention using an ALD method, it is possible to reduce impurities generated in a thin film by subreactions because there is no movement of the radicals.

In the method of forming a thin metal oxide film using an ALD method according to another embodiment of the present invention, it is possible to prevent generation of by-products such as hydroxide in the metal oxide film by reducing the absolute amount of the first reactant by previously reacting the first reactant is reduced with a second reactant containing no hydroxide, and then the first reactant is reacted with a third reactant containing a hydroxide. For example, it is possible to form an aluminum oxide film in which the absolute amount of hydroxide is small by reducing the absolute amount of trimethylaluminum by previously reacting trimethylaluminum with N ₂ O containing no hydroxide, and then the trimethylaluminum with water vapor is reacted.

Furthermore, in the method of forming a thin film using an ALD method according to another embodiment of the present invention, a third reactant for removing the impurities and improving the stoichiometry of the thin film is injected into the reaction chamber, and the reaction chamber is purged of the third reactant the atomic layer deposition method is used. Thereby, it is possible to obtain a thin film having an excellent stoichiometry containing no impurities.

Claims (21)

A method of producing an alumina thin film using an atomic layer deposition (ALD) method comprising the steps of: injecting a first reactant containing a thin film forming species and a ligand into a reaction chamber including a substrate so that the first reactant is chemisorbed into the substrate, removing any first reactant physisorbed into the substrate merely by purging the reaction chamber with inert gas, forming a thin film in units of atomic layers by a chemical reaction between the thin film forming one An atomic species and a second reactant whose binding energy with respect to the thin-film forming atomic species is greater than the binding energy of the ligand with respect to the thin-film forming atomic species by injecting the second reactant into the reaction chamber and removing the ligand without generating by-products, e.g. nd - removing any physisorbed second reactant by purging the chamber with inert gas after the step of injecting the second reactant, - wherein the first reactant is Al (CH ₃ ) ₃ and the second reactant is an oxidizing agent selected from the group consisting of O ₃ , O ₂ plasma and N ₂ O plasma. The method of claim 1, further characterized in that the steps from the step of injecting the first reactant to the step of removing any physisorbed second reactant are repeated once or several times as needed. A method of forming a metal oxide thin film using an ALD method comprising the steps of: injecting a first reactant, which is a metal reactant, into a reaction chamber containing a substrate such that the first reactant is chemisorbed into the substrate; Removing any first reactant that is merely physisorbed into the substrate by purging the reaction chamber with inert gas, - chemically exchanging the chemisorbed first reactant to form a film of an atomic metal-oxygen layer by adding a second reactant, the contains no hydroxide and reacts with the chemisorbed first reactant, injected into the reaction chamber, the second reactant being N ₂ O, O ₂ , O ₃ or CO ₂ , - removing any physisorbed second reactant by purging the reaction chamber with inert gas, Forming the thin film in the form of a metal oxide film in units of atomic shear By injecting water vapor as a third reactant other than the second reactant into the reaction chamber, the remaining chemisorbed first reactant reacts with the third reactant to be chemically exchanged to further contribute to the formation of the atomic metal-oxygen layer Generation of a hydroxide is prevented, and - removing any physisorbed third reactant by purging the reaction chamber with inert gas after the step of injecting the third reactant into the reaction chamber. The method of claim 3, further characterized in that the temperature of the reaction chamber from the step of injecting the first reactants to the step of injecting the third reactant is maintained between 100 ° C and 400 ° C. The method of claim 3 or 4, further characterized in that the metal oxide film is selected from the group consisting of an Al ₂ O ₃ film, a TiO ₂ film, a ZrO ₂ film, an HfO ₂ film, a Ta ₂ O ₅ film, Nb ₂ O ₆ film, CeO ₂ film, Y ₂ O ₃ film, SiO ₂ film, In ₂ O ₃ film, RuO ₂ film, IrO ₂ Film, SrTiO ₃ film, PbTiO ₃ film, SrRuO ₃ film, CaRuO ₃ film, (Ba, Sr) TiO ₃ film, Pb (Zr, Ti) O ₃ film, a (Pb, La) (Zr, Ti) O ₃ film, a (Sr, Ca) RuO ₃ film, a (Ba, Sr) RuO ₃ film, a Sn doped In ₂ O ₃ (ITO) - Film and a doped with Zr In ₂ O ₃ film consists. A method according to any one of claims 3 to 5, further characterized in that the unpaired bonding of the surface of the substrate by injecting an oxidizing gas before the Injecting the first reactant is saturated when the substrate is a silicon substrate. The method of any one of claims 3 to 6, further characterized in that the steps from the step of injecting the first reactant to the step of removing any physisorbed third reactant are repeated once or several times as needed. The method of any of claims 3 to 7, further characterized by comprising a step of injecting a fourth reactant to remove impurities and to improve the stoichiometry of the metal oxide film into the reaction chamber after the step of removing the physisorbed third reactant. The method of claim 8, further characterized in that the fourth reactant is ozone gas. A method of forming a metal oxide or metal nitride thin film using an ALD method, characterized by the steps of: injecting a first reactant into a reaction chamber equipped with a substrate such that the first reactant is chemisorbed into the substrate; Removing any first reactant merely physisorbed into the substrate by purging the reaction chamber with inert gas, forming a thin film in units of atomic layers by injecting a second reactant into the reaction chamber, and chemically exchanging the first reactant with the second reactant wherein the second reactant is water vapor in the case of forming a metal oxide thin film and NH ₃ in the case of forming a metal nitride thin film, removing any physisorbed second reactant by purging the reaction chamber with inert gas, injecting one different from the second reactant third reactants for removing impurities and improving the stoichiometry of the preformed thin film into the reaction chamber, removing any physisorbed third reactant by purging the reaction chamber with inert gas after the step of injecting the third reactant. The method of claim 10, further characterized in that the first reactant is a metal reactant and the third reactant is an oxidizing gas in the case of forming a metal oxide thin film. A method according to claim 10 or 11, further characterized in that the thin film is a metal oxide film consisting of a monatomic oxide or a composite oxide. The method of claim 12, further characterized in that said monatomic oxide is selected from the group consisting of Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₆ , ZrO ₂ , HfO ₂ , Nb ₂ O ₆ , CeO ₂ , Y ₂ O ₃ , SiO ₂ , In ₂ O ₃ , RuO ₂ and IrO ₂ . The method of claim 13, further characterized in that said composite oxide is selected from the group consisting of SrTiO ₃ , PbTiO ₃ , SrRuO ₃ , CaRuO ₃ , (Ba, Sr) TiO ₃ , Pb (Zr, Ti) O ₃ , (Pb, La) (Zr, Ti) O _3, (Sr, Ca) RuO _3, Sn-doped In ₂ O _3, Fe-doped In ₂ O ₃ and Zr-doped In ₂ O _3. The method of claim 10, further characterized in that the first reactant is a metal reactant and the third reactant is a nitriding gas in the case of forming a metal nitride thin film. The method of claim 10 or 15, further characterized in that the thin film is a metal nitride film consisting of a monatomic nitride or a composite nitride. The method of claim 16, further characterized in that said monatomic nitride is selected from the group consisting of SiN, NbN, ZrN, TiN, TaN, Ya ₃ N ₅ , AlN, GaN, WN and BN. The method of claim 16, further characterized in that the composite nitride is selected from the group consisting of WBN, WSiN, TiSiN, TaSiN, AlSiN and AlTiN. The method of any one of claims 10 to 18, further characterized in that the unpaired bond of the surface of the substrate is saturated by injecting an oxidizing or nitriding gas prior to injecting the first reactant when the substrate is a silicon substrate. The method of any of claims 10 to 19, further characterized in that the temperature of the reaction chamber is maintained from the step of injecting the first reactant to the step of injecting the third reactant between 100 ° C and 400 ° C. A method according to any one of claims 10 to 20, further characterized in that the steps from the step of injecting the first reactant to the step of removing the first reactant physisorbed third reactants may be repeated once or several times as needed.

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