KR20180000418A - Preparing method of cobalt-containing thin film - Google Patents

Abstract

More particularly, the present invention relates to a method for producing a cobalt-containing thin film using a plasma enhanced atomic layer deposition method, and more particularly, to a method for producing a cobalt-containing thin film by alternately supplying a cobalt precursor and a first plasma reaction gas, Forming a thin film; And heat treating the cobalt-containing thin film to remove impurities, or alternately supplying a cobalt precursor, a first plasma reaction gas, and a second plasma reaction gas to form a cobalt-containing thin film on the substrate do.

Description

TECHNICAL FIELD [0001] The present invention relates to a cobalt-containing thin film,

The present invention relates to a method for producing a cobalt-containing thin film by plasma enhanced atomic layer deposition.

Cobalt is an important transition metal in semiconductor devices. Cobalt has a low resistance, high resistance to oxidation, and excellent wetting and magnetic properties with copper, so that contact with interconnection, copper wire, copper capping layer, and magnetic memory element Are being used in various fields.

As a result of scaling reduction to increase the integration of CMOS devices, high functionality and fast processing speed are obtained. Successive scaling progresses to increase the degree of integration, reaching the nanometer range. Nanometer-scale device performance is strongly affected by resistance, capacitance, and inductance. Among the factors that determine device performance, resistance consists of parasitic resistance and channel resistance. Among them, the parasitic resistance is composed of the contact resistance between the sheet resistance and the metal-semiconductor at the junction. The increase in parasitic resistance due to the scaling of the transistor reduces the driving current and causes the performance degradation of the device.

A method of reducing parasitic resistance is to form a metal silicide with low resistivity at the source and drain. When the silicide is formed in the source and the drain, the voltage drop phenomenon can be reduced and the driving current can be improved. Such a metal silicide is applied to a gate (word current line) and a first interconnect level (bit line) in a memory device such as a DRAM and is formed on a source, a drain, and a gate in a logic device.

The first metal silicide used in the integrated circuit is TiSi ₂ . TiSi ₂ was used up to 180 nm CMOS devices due to its low resistivity. However, as the linewidth decreases due to continuous scaling, the formation of C49 TiSi ₂ increases rather than the formation of low resistivity C54 TiSi ₂ , resulting in a narrow linewidth effect in which the sheet resistance increases. As a result, Less new silicide research is needed. Therefore, cobalt silicide (CoSi ₂ ) and nickel silicide (NiSi), which are less affected by such narrow linewidth effects, are used in devices after 180 nm.

NiSi has a relatively low resistivity, low silicon consumption, low silicide formation temperature, and no resistance increase in fine line width. However, since the thermal stability is relatively low, when the NiSi is higher than 750 ° C, the sheet resistance is increased and the sheet resistance is increased due to the high specific resistance NiSi ₂ . Therefore, it is not suitable for a device in which a high temperature treatment process is performed after the formation of the silicide.

CoSi ₂ has the advantage of low resistivity, high thermal stability, low line width effect, and low lattice mismatch with Si. CoSi ₂ is formed at a temperature of about 550 ° C or more and is stable up to about 950 ° C. These advantages are suitable for devices in which a high temperature process is performed after silicide formation.

Deposition of Co thin film on Si is required for CoSi ₂ formation in devices such as DRAM or 3D NAND flash memory. Sputtering, which is one of the PVD methods, is used to deposit a Co thin film, but there is a problem in that scaling of the device is progressed and a thin film having a conformal thickness can not be deposited in a high aspect ratio structure. To solve this problem, a chemical vapor deposition (CVD) method and an atomic layer deposition (ALD) method having superior step coverage characteristics are being studied. The CVD method has been studied using an organometallic precursor, which shows a problem that the content of carbon (C) impurities is very high in the thin film. Since ALD has very high step coverage properties, it is an ideal method for depositing Co thin films required for CoSi ₂ formation because it can deposit uniform thin films in a high aspect ratio structure and is advantageous for depositing high purity thin films. Therefore, it is required to study the deposition of cobalt thin films using ALD.

Meanwhile, Han-Bo-Ram Lee, in relation to cobalt ALD, has a structure of amidinate ligand, Co (iprAMD) ₂ [bis (N, N'-diisopropyl-acetamidinate) cobalt And H ₂ and NH ₃ as reaction gases [HBR Lee, WH Kim, JW Lee, JM Kim, K. Heo, IC Hwang, Y. Park, S. Hong and H Kim. Journal of The Electrochemical Society, 157 (2010) 1D10]. First, when H ₂ was used as the reaction gas, the growth rate was 0.43 Å at 350 ° C. However, the resistivity of the thin film showed a high resistance of ~ 200 μΩ · cm, and Co-O and O peaks were detected in the thin film through XPS. The density of the thin film was 62% of the bulk cobalt. NH ₃ reaction gas exhibited a relatively low growth rate of 0.26 Å, but had a lower resistivity value of ~ 50 μΩ · cm, a sharp Co-Co peak due to XPS, and a relatively high film density of 79% Respectively. However, the thermal stability of the precursor is so high that there is a problem of a high temperature process of 350 ° C.

Thus, in the prior art, most of the organometallic precursors have been studied using cobalt precursors with ligands such as carbonyl (CO), cyclopentadienyl (Cp), and amidinate (AMD). In the previous research, the thermal stability due to the bonding force between Co and the ligand is low, so that the precursor is thermally decomposed to deposit a Co thin film containing C impurity or a high thermal stability. Therefore, it is necessary to study ALD Co thin film deposition with low impurity at low temperature.

The present invention provides a method for producing a cobalt-containing thin film using plasma enhanced atomic layer deposition (PEALD).

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

One aspect of the present invention provides a method of forming a cobalt-containing thin film on a substrate by alternately supplying a cobalt precursor and a first plasma reactive gas to form a cobalt-containing thin film on the substrate; And a step of heat treating the cobalt-containing thin film to remove impurities.

Another aspect of the present invention provides a process for preparing a cobalt-containing thin film comprising: alternately feeding a cobalt precursor, a first plasma reactive gas, and a second plasma reactive gas to form a cobalt-containing thin film on a substrate .

The method of manufacturing a cobalt-containing thin film according to an embodiment of the present invention can form a film having a high purity at a low temperature as compared with a conventional process. By depositing a cobalt-containing film using the PEALD method, excellent step coverage And the deposition of a homogeneous film is possible. Further, by using the PEALD process using radicals having excellent reactivity, a cobalt-containing thin film having a small content of impurities can be provided.

By using the cobalt precursor according to an embodiment of the present invention, it is possible to deposit a Co thin film having a low impurity (carbon) content at a temperature lower than the ALD process temperature using the conventional cobalt precursor and to form a cobalt suicide by the additional heat treatment .

Figure 1 is a simplified schematic diagram of a plasma enhanced atomic layer deposition system in accordance with one embodiment of the present disclosure.
2A is a graph showing changes in mass per deposition cycle obtained by QCM measurement according to the pulse time of Co (dpdab) ₂ in one comparative example of the present application.
FIG. 2B is a graph showing mass change per deposition cycle obtained by QCM measurement according to the pulse time of NH ₃ in one comparative example of the present application. FIG.
FIG. 3A is a photograph showing the surface shape of a cobalt film deposited using NH ₃ as a reactive gas at 250 ° C. in one comparative example of the present application.
3B is a photograph showing the surface shape of a cobalt film deposited using NH ₃ as a reactive gas at 300 ° C in one comparative example of the present application.
4A is a Raman spectrum of a cobalt film deposited on a Si substrate using NH ₃ as a reactive gas in one comparative example of the present application.
4B is a Raman spectrum of a cobalt film deposited on a Pt substrate using NH ₃ as a reactive gas in one comparative example of the present application.
5 is an XRD pattern of a cobalt film deposited on a Pt substrate using NH ₃ as a reactive gas at different temperatures, in one comparative example of the present application.
FIG. 6A is a photograph showing the surface shape of a cobalt film deposited by using H ₂ as a reactive gas at 250 ° C. in one comparative example of the present application. FIG.
6B is a photograph showing the surface shape of a cobalt film deposited using H ₂ as a reactive gas at 300 ° C in one comparative example of the present application.
7A is a Raman spectrum of a cobalt film deposited on a Si substrate using H ₂ as a reactive gas in one comparative example of the present application.
7B is a Raman spectrum of a cobalt film deposited on a Pt substrate using H ₂ as a reactive gas in one comparative example of the present application.
8 is an XRD pattern of a cobalt film deposited on a Pt substrate using H ₂ as a reactive gas at different temperatures, in one comparative example of the present application.
FIG. 9 is a graph showing sheet resistance of a PEALD cobalt film with Co (dpdab) ₂ exposure time in one embodiment of the present invention.
10 is a graph showing the rate of growth per cycle and the sheet resistance according to NH ₃ plasma time in one embodiment of the present invention.
11A shows the chemical composition of the cobalt film measured by AES in one embodiment of the present invention, and the plasma treatment time was 10 seconds.
FIG. 11B shows the chemical composition of the cobalt film measured by AES in one embodiment of the present invention, and the plasma treatment time was 30 seconds.
12 is a graph showing the growth rate and resistivity per cycle of the PEALD cobalt film according to the deposition temperature in one embodiment of the present invention.
(A) 120 ° C, (b) 150 ° C, (c) 200 ° C, (d) 250 ° C, and (e) 300 ° C, respectively, in one embodiment of the present application. TEM image of a PEALD cobalt film deposited at.
14 is a graph showing the sheet resistance of a PEALD cobalt film according to RF power in an embodiment of the present invention.
15 is a graph showing the thickness and sheet resistance of the PEALD cobalt film according to the number of ALD cycles in one embodiment of the present invention.
16 (a) - (d) are TEM cross-sectional photographs of a PEALD cobalt film deposited on a trench pattern with an aspect ratio of 7, in one embodiment of the present application.
17A is a graph showing AES depth profiling of a PEALD cobalt film deposited using NH ₃ plasma, in one embodiment of the present invention.
Figure 17B is a graph showing AES depth profiling of a PEALD cobalt film deposited using H ₂ plasma, in one embodiment of the invention.
18 is a graph showing AES depth profiling after annealing a PEALD cobalt film deposited using NH ₃ plasma in an H ₂ atmosphere at 400 ° C for 30 minutes, in one embodiment of the present invention.
19 shows the XRD pattern of a PEALD cobalt film before and after annealing at 400 DEG C for 30 minutes in an H ₂ atmosphere in an embodiment of the present invention.
Figure 20 shows the thickness and sheet resistance of a PEALD cobalt film deposited using a different reactive gas, respectively, in one embodiment of the invention.
Figure 21 is a graph showing AES depth profiling of a PEALD cobalt film deposited using a mixed plasma of NH ₃ and H ₂ , in one embodiment of the present application.
22A is a TEM cross-sectional photograph of a cobalt film on a Si substrate, prior to the silicidation annealing process, in one embodiment of the present invention.
Figure 22B is a TEM cross-sectional photograph of a cobalt film on a Si substrate after silicidation annealing treatment at 700 占 폚 for one minute in one embodiment of the invention.
23 shows the XRD pattern of a PEALD cobalt film before and after an RTP process in an N ₂ atmosphere at 700 ° C for one minute in one embodiment of the present invention.

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. It should be understood, however, that the present invention may be embodied in many different forms and is not limited to the embodiments and examples described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is "on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

As used herein, the terms "about," " substantially, "and the like are used herein to refer to or approximate the numerical value of manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to prevent unauthorized exploitation by unauthorized intruders of the mentioned disclosure.

The term " step " or " step of ~ " as used throughout the specification does not imply " step for.

Throughout this specification, the term "combination (s) thereof " included in the expression of the machine form means a mixture or combination of one or more elements selected from the group consisting of the constituents described in the expression of the form of a marker, Quot; means at least one selected from the group consisting of the above-mentioned elements.

Throughout this specification, the description of "A and / or B" means "A or B, or A and B".

Throughout the present specification, the term "film" is used in the sense of including films of all possible thicknesses and means including thin films.

As used throughout this specification, the term "alkyl ", when not otherwise defined, when used alone or in combination with other terms such as" alkoxy ", "arylalkyl "," alkanolamine ", and "alkoxyamine" Having from about 1 to about 20 carbon atoms, or from about 1 to about 20 carbon atoms, or from about 1 to about 12 carbon atoms, or from about 1 to about 10 carbon atoms, or from about 1 to about 6 carbon atoms Or branched alkyl groups. For example, the alkyl may be methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, pentyl, hexyl, isohexyl, heptyl, 4-trimethylpentyl, nonyl, decyl, undecyl, dodecyl and isomers thereof, but are not limited thereto.

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments and examples and drawings.

One aspect of the present invention provides a method of forming a cobalt-containing thin film on a substrate by alternately supplying a cobalt precursor and a first plasma reactive gas to form a cobalt-containing thin film on the substrate; And a step of heat treating the cobalt-containing thin film to remove impurities.

First, a cobalt precursor and a first plasma reactive gas are alternately supplied on a substrate to form a cobalt-containing thin film.

In one embodiment herein, the substrate may be a Si, Si wafer, undoped poly-Si wafer, doped poly-Si wafer, epitaxial Si, epitaxial SiGe, poly-SiGe, epitaxial Ge, _{, SiO 2, SiOC SiN, SiCN} , SiC, SiBN, SiBCN, BN, BCN, Cu, Cu (Ti), Cu (Al), Cu (Mn), But are not limited to, Ti, TiN, TiC, TiCN, Ta, TaN, TaC, TaCN, W, WN, WC, Al, and combinations thereof.

In one embodiment of the present invention, the cobalt precursor may comprise a compound represented by the following Formula 1:

[Chemical Formula 1]

;

;

In Formula 1, R ₁ to R ₄ each independently represent a C ₁ to C ₆ linear or branched alkyl group, or an isomer thereof.

For example, the cobalt precursor may be Co (dpdab) ₂ , CpCo (CO) ₂ [cyclopentadienyl cobaltylcarbonyl], CoCp ₂ (2-tert-butylallyl) cobalt tricarbonyl], Co (iPrNCMeNiPr) ₂ , bis (cyclopentadienyl) cobalt II, dicobalt hexacarbonyl tert-butylacetylene CCTBA, _{Co 2 (CO) 8, Co} (C 5 H 5) (iPrNCMeNiPr), cyclopentadienyl-isopropyl-acetamido Dina soil-consisting of cobalt [cyclopentadienyl isopropyl acetamidinato-cobalt, Co (CpAMD)], and combinations thereof But are not limited to, those selected from the group consisting < RTI ID = 0.0 > of: < / RTI >

In one embodiment of the present application, the first plasma reactive gas comprises a nitrogen-containing gas; A mixed gas of hydrogen (H ₂ ) gas and nitrogen-containing gas; Or a mixed gas of an inert gas and a nitrogen-containing gas. For example, the nitrogen-containing gas is _{NH 3, N 2, N 2} H 4, N 2 H x Me 4 -x (x is an integer of less than _{3), R x NH 3 -x} (R is C ₁ to C ₆ alkyl group and x is 1 or 2), R _x N ₂ H _{4 -x} (R is a C ₁ to C ₆ alkyl group, x is an integer of 3 or less), and combinations thereof. For example, the inert gas may include, but is not limited to, a gas selected from the group consisting of He, Ne, Ar, and combinations thereof.

In one embodiment of the present invention, forming the cobalt-containing thin film may be performed by atomic layer deposition, and the atomic layer deposition method includes plasma enhanced atomic layer deposition (PEALD) . PEALD generates a deposition reaction using a radical reaction and ion bombardment rather than a ligand exchange between a precursor and a reactive gas. PEALD has the advantage of forming a thin film of higher quality than thermal ALD and reducing the processing time. In addition, the use of a radical having excellent reactivity enables the reaction to be carried out at a temperature lower than that of thermal ALD. 1 is a schematic diagram of a PEALD system in accordance with an embodiment of the present disclosure; The PEALD process according to one embodiment of the present invention will be described with reference to FIG. 1, wherein the showerhead and wafer chunk are spaced about 1 cm to about 5 cm apart in parallel and RF power is applied to the showerhead , The wafer chunk is grounded to form a plasma directly therebetween. The plasma is a method of forming highly reactive radicals so that the reaction with the precursor occurs more easily. Direct plasma has the advantage of higher radical efficiency than remote plasma because it forms plasma on the wafer.

In one embodiment of the present invention, forming the cobalt-containing thin film may be performed at a temperature ranging from about 100 ° C to about 300 ° C, but is not limited thereto. For example, the temperature at the formation of the cobalt-containing thin film may be about 100 캜 to about 300 캜, about 100 캜 to about 250 캜, about 100 캜 to about 200 캜, about 100 캜 to about 150 캜, About 300 ° C, about 200 ° C to about 300 ° C, about 250 ° C to about 300 ° C, or about 150 ° C to about 250 ° C.

Subsequently, the cobalt-containing thin film is heat-treated to remove impurities to produce a high purity cobalt-thin film.

In one embodiment of the invention, the heat treatment may include, but is not limited to, heat treatment using plasma. The heat treatment using the plasma may be performed under the supply of the second plasma reaction gas. The second plasma reactive gas comprises a hydrogen-containing gas; Or a mixed gas of an inert gas and a hydrogen-containing gas. For example, the hydrogen-containing gas may comprise hydrogen (H ₂ ) gas, for example, the inert gas may be a gas selected from the group consisting of He, Ne, Ar, But are not limited thereto.

In one embodiment of the invention, the heat treatment may be performed under a hydrogen gas supply. Impurities of the cobalt-containing thin film can be removed by heat treatment in a hydrogen atmosphere, and impurities of the cobalt-containing thin film can be removed to provide a high purity cobalt-containing thin film.

In one embodiment of the invention, the heat treatment may be performed at a temperature ranging from about 100 < 0 > C to about 700 < 0 > C, but is not limited thereto. For example, the heat treatment temperature may be from about 100 ° C to about 700 ° C, from about 100 ° C to about 600 ° C, from about 100 ° C to about 500 ° C, from about 100 ° C to about 400 ° C, About 400 deg. C to about 700 deg. C, about 500 deg. C to about 700 deg. C, or about 600 deg. C to about 700 deg. C, But is not limited thereto.

In one embodiment of the invention, the cobalt-containing thin film may include, but is not limited to, an impurity content of about 5% or less. For example, the content of the impurity element may be less than about 5%, less than about 4%, less than about 3%, less than about 2%, less than about 1%, less than about 0.5%, less than about 0.1% 5%, about 1% to about 4%, or about 2% to about 3%.

For example, the impurity may include, but is not limited to, an element selected from the group consisting of carbon, nitrogen, and combinations thereof.

The method of manufacturing a cobalt-containing thin film according to an embodiment of the present invention may further include the step of subjecting the cobalt-containing thin film to a second heat treatment to form a silicide after the heat treatment, But is not limited thereto. In one embodiment of the present invention, the secondary heat treatment may be performed at a temperature ranging from about 400 ° C to about 1,100 ° C. For example, the secondary heat treatment temperature may be from about 400 ° C to about 1,100 ° C, from about 400 ° C to about 1,000 ° C, from about 400 ° C to about 900 ° C, from about 400 ° C to about 800 ° C, From about 400 ° C to about 600 ° C, from about 400 ° C to about 500 ° C, from about 500 ° C to about 1,100 ° C, from about 600 ° C to about 1,100 ° C, from about 700 ° C to about 1,100 ° C, Deg.] C to about 1,100 [deg.] C, or from about 1,000 [deg.] C to about 1,100 [deg.] C. When the heat treatment is performed at a high temperature, the heat treatment time can be shortened to several tens of ms. When the heat treatment is performed under the supply of the second plasma reaction gas, Impurities can be removed.

Another aspect of the present invention provides a process for preparing a cobalt-containing thin film comprising: alternately feeding a cobalt precursor, a first plasma reactive gas, and a second plasma reactive gas to form a cobalt-containing thin film on a substrate .

In one embodiment herein, the substrate may be a Si, Si wafer, undoped poly-Si wafer, doped poly-Si wafer, epitaxial Si, epitaxial SiGe, poly-SiGe, epitaxial Ge, _{, SiO 2, SiOC SiN, SiCN} , SiC, SiBN, SiBCN, BN, BCN, Cu, Cu (Ti), Cu (Al), Cu (Mn), But are not limited to, Ti, TiN, TiC, TiCN, Ta, TaN, TaC, TaCN, W, WN, WC, Al, and combinations thereof.

In one embodiment of the present invention, the cobalt precursor may comprise a compound represented by the following Formula 1:

[Chemical Formula 1]

;

;

In Formula 1, R ₁ to R ₄ each independently represent a C ₁ to C ₆ linear or branched alkyl group, or an isomer thereof.

For example, the cobalt precursor may be Co (dpdab) ₂ , CpCo (CO) ₂ [cyclopentadienyl cobaltylcarbonyl], CoCp ₂ (2-tert-butylallyl) cobalt tricarbonyl], Co (iPrNCMeNiPr) ₂ , bis (cyclopentadienyl) cobalt II, dicobalt hexacarbonyl tert-butylacetylene CCTBA, _{Co 2 (CO) 8, Co} (C 5 H 5) (iPrNCMeNiPr), cyclopentadienyl-isopropyl-acetamido Dina soil-consisting of cobalt [cyclopentadienyl isopropyl acetamidinato-cobalt, Co (CpAMD)], and combinations thereof But are not limited to, those selected from the group consisting < RTI ID = 0.0 > of: < / RTI >

In one embodiment of the present application, the first plasma reactive gas comprises a nitrogen-containing gas; A mixed gas of hydrogen (H ₂ ) gas and nitrogen-containing gas; Or a mixed gas of an inert gas and a nitrogen-containing gas. For example, the nitrogen-containing gas is _{NH 3, N 2, N 2} H 4, N 2 H x Me 4 -x (x is an integer of less than _{3), R x NH 3 -x} (R is C ₁ to C ₆ alkyl group and x is 1 or 2), R _x N ₂ H _{4 -x} (R is a C ₁ to C ₆ alkyl group, x is an integer of 3 or less), and combinations thereof. , But is not limited thereto. For example, the inert gas may include, but is not limited to, a gas selected from the group consisting of He, Ne, Ar, and combinations thereof.

In one embodiment of the present application, the second plasma reactive gas comprises a hydrogen-containing gas; Or a mixed gas of an inert gas and a hydrogen-containing gas. For example, the hydrogen-containing gas may comprise hydrogen (H ₂ ) gas, for example, the inert gas may be a gas selected from the group consisting of He, Ne, Ar, But are not limited thereto.

In one embodiment of the invention, forming the cobalt-containing thin film may be performed by atomic layer deposition, and the atomic layer deposition method includes plasma enhanced atomic layer deposition (PEALD). PEALD generates a deposition reaction using a radical reaction and ion bombardment rather than a ligand exchange between a precursor and a reactive gas. PEALD has the advantage of forming a thin film of higher quality than thermal ALD and reducing the processing time. In addition, the use of a radical having excellent reactivity enables the reaction to be carried out at a temperature lower than that of thermal ALD.

In one embodiment of the invention, forming the cobalt-containing thin film may be performed at a temperature ranging from about 100 ° C to about 300 ° C. For example, the temperature at the formation of the cobalt-containing thin film may be about 100 캜 to about 300 캜, about 100 캜 to about 250 캜, about 100 캜 to about 200 캜, about 100 캜 to about 150 캜, About 300 ° C, about 200 ° C to about 300 ° C, about 250 ° C to about 300 ° C, or about 150 ° C to about 250 ° C.

In one embodiment of the invention, the cobalt-containing thin film may include, but is not limited to, an impurity content of about 5% or less. For example, the content of the impurity element may be less than about 5%, less than about 4%, less than about 3%, less than about 2%, less than about 1%, less than about 0.5%, less than about 0.1% 5%, about 1% to about 4%, or about 2% to about 3%.

For example, the impurity may be a material including, but not limited to, an element selected from the group consisting of carbon, oxygen, nitrogen, and combinations thereof.

The method of manufacturing a cobalt-containing thin film according to an embodiment of the present invention may further include the step of subjecting the cobalt-containing thin film to a heat treatment to suicide the substrate, wherein the substrate may include Si. In one embodiment of the invention, the heat treatment may be performed at a temperature ranging from about 400 ° C to about 1,100 ° C, but is not limited thereto. For example, the heat treatment temperature may range from about 400 ° C to about 1,100 ° C, from about 400 ° C to about 1,000 ° C, from about 400 ° C to about 900 ° C, from about 400 ° C to about 800 ° C, About 900 ° C to about 600 ° C, about 400 ° C to about 500 ° C, about 500 ° C to about 1,100 ° C, about 600 ° C to about 1,100 ° C, about 700 ° C to about 1,100 ° C, About 1,100 ° C, or about 1,000 ° C to about 1,100 ° C. When the heat treatment is performed at a high temperature, the heat treatment time can be shortened to several tens of milliseconds.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

[ Example ]

One. ALD  Preparation of cobalt-containing thin film used

In this Example, Co (dpdab) ₂ was used as a cobalt precursor, and basic physical properties of Co (dpdab) ₂ and a DCS graph are shown in Table 1 below. The molecular weight of Co (dpdab) ₂ was 339.39 g / mol, and the vapor pressure at 80 ℃ was 0.22 torr. Also, as shown in the DCS graph, Co (dpdab) ₂ shows a pyrolysis reaction at 275 ° C, which indicates that an ALD reaction occurs at a temperature of 275 ° C or lower.

[Table 1]

2. Heat ALD  Preparation of cobalt-containing thin film used

Comparative Example  1: heat ALD  Preparation of cobalt-containing thin film used 1

In this comparative example, ALD equipment in the form of a furnace was used to perform thermal ALD. As the base material, Si and Pt / SiO ₂ / Si having a size of 20 mm × 20 mm were used. Platinum (Pt) was deposited on a SiO ₂ wafer formed by thermal oxidation using a sputtering method. First, the substrates were placed on a holder of a batch type and placed in a chamber of a furnace type. Subsequently, the interior was slowly pumped using a bypass line, and the main valve was opened at less than 10 torr and pumped rapidly. At this time, Ar was introduced to raise the pressure of the reaction tube, and then the purging process to make the vacuum state again was repeated to minimize the amount of oxygen and moisture remaining in the reaction tube. A substrate heater, an ampoule heater, a gas line, etc. were heated to a predetermined temperature and maintained for 1 hour so that the temperature could be stabilized. After the temperature stabilization, the main valve was closed to check the amount of leakage, and the leak rate was confirmed by dividing the increase in pressure by time. The experiment was repeated with the deposition cycle according to the desired manufacturing method. During the process, sufficient purging and purge times were given between each source injection to separate the raw materials. At the end of the process, the sample was purged while waiting for the temperature to become sufficiently low to prevent thermal stress and oxidation of the film. The characteristics of the thin films were verified by using various analytical methods.

First, we investigated the ALD growth characteristics of cobalt thin films with quartz crystal microbalance (QCM) according to the supply amounts of Co (dpdab) ₂ and NH ₃ gas. The variation of the frequency obtained from the QCM was calculated by calibrating the mass change through the Sauer-Bray equation (Δf = -C Δm).

FIGS. 2A and 2B show the deposition reaction at 250 ° C according to the amounts of Co (dpdab) ₂ and NH ₃ supplied. The supply amount of NH ₃ gas was fixed at 1 × 10 9 L. The supply of Co (dpdab) ₂ was carried out by bubbling, and the supply time of Co (dpdab) ₂ was changed from 10 s The change in QCM frequency was measured while increasing to 40 seconds. As a result, it was confirmed that the variation of the frequency was constant at 41 ng · cm ^{- 2} cy ^-1 when the supply amount of Co (dpdab) ₂ was more than 15 seconds. Indicating that the chemical adsorption reaction between the substrate and the precursor was saturated at 15 seconds. In addition, the change of QCM frequency was confirmed by fixing Co (dpdab) ₂ at 20 seconds and increasing the supply amount of NH ₃ gas from 12 to 112 seconds. In the case of NH ₃ , it was confirmed that the change in the frequency was constant at 56 seconds. This indicates that a self-limiting surface reaction of the raw material and the reaction gas occurs. Deposition characteristics were observed according to the variation of the deposition temperature at the feed rate at which this self-controlled surface reaction occurs. The film was deposited at 200 ℃ ~ 300 ℃ under the conditions of Co (dpdab) _{2 for} 20 seconds and NH _{3 for} 56 seconds in which ALD reaction occurred at 250 ℃. No deposition reaction was observed at 200 ℃. 3A and 3B are SEM photographs showing the surface shape according to the deposition temperature. 3A, it was confirmed that a Co thin film was not deposited on the Si substrate and a Co thin film of 20 nm was deposited on the Pt substrate at 250 ° C. This can be confirmed through the sheet resistance. The sheet resistance before deposition on the Si substrate was 121.2? /?, And the sheet resistance after deposition was 126.5? /?, Which did not show a large difference. In addition, selective properties were observed in which the thin film was deposited only on the Pt substrate. However, as shown in FIG. 3B, at 300 ° C, it was confirmed that a very thick and continuous Co thin film was deposited on both Pt and Si substrates to lose selective characteristics. The sheet resistance value was also significantly reduced to 1.59? /? After deposition on the Si substrate. In order to confirm the crystal structure of the thin films showing these properties, Raman and XRD were used.

4A and 4B show a Raman spectroscopy spectrum according to deposition temperature and substrate. As shown in FIG. 4A, only the Si peak was confirmed on the Si substrate deposited at 250 ° C., and it was confirmed that the thin film was not deposited. As shown in FIG. 4B, in the Pt substrate, a considerably large amount of amorphous carbon , aC) peaks were confirmed. It was confirmed that the carbon of the Co precursor was not completely removed during the ALD deposition at 250 ° C, and the impurity carbon was contained in the thin film. The a-C peak of the Si substrate deposited at 300 캜 was confirmed. In the Pt substrate, slight cobalt oxide peak and a-C peak were confirmed. The cobalt oxide peak was caused by the reaction of cobalt with oxygen when exposed to air because the film quality of the deposited thin film was not good.

Then, the crystal structure of the Pt substrate deposited at 250 캜 and 300 캜 was analyzed by XRD. 5 shows the XRD spectrum of the crystal structure of the Pt substrate according to the deposition temperature. As shown in FIG. 5, the Co thin film deposited at 250 ° C was able to identify the Co (101) peak (JCPDS, No. 01-1277) and the Co ₂ N (210) peak (JCPDS 65-1458). In 300 ℃ Co (N (CN) 2) 2 (110) peak (JCPDS, No. 89-0768), Co (N (CN) 2) 2 (111) peak, Co (101) peak, Co ₂ N (210) peak, and C (002) peak (JCPDS, No. 75-1621). From the above results, it was confirmed that the thin film deposited using Co (dpdab) ₂ and NH ₃ at 250 ° C. exhibited ALD deposition characteristics, but the cobalt-containing thin film containing a large amount of C and N was deposited. In addition, Co (N (CN) ₂ ) ₂ , Co ₂ N, Co, and C etc. identified in the cobalt-containing thin film deposited at 300 ° C were part of the precursor ligand, That is, it was confirmed that the film was deposited by thermal decomposition of the cobalt precursor at 300 ° C.

Comparative Example  2: heat ALD  Preparation of used cobalt-containing thin film 2

A Co thin film was deposited by changing the reaction gas to H ₂ under the same conditions as in Comparative Example 1. 6A and 6B are SEM photographs showing the surface morphology according to the deposition temperature and substrate. As shown in FIG. 6A, it was confirmed that no thin film was deposited on the Si substrate at 250 ° C., and a thin film of 10 nm was deposited on the Pt substrate. This shows the same selective characteristics as the NH ₃ reaction gas of Comparative Example 1. Further, as shown in FIG. 6B, the Co thin film on the Si substrate at 300 ° C showed island growth rather than a continuous thin film different from that of Comparative Example 1, and a continuous thin film was deposited on the Pt substrate . When the sheet resistance of the deposited thin film was measured, the sheet resistance of the Si substrate was 121.2? /? Before the deposition and 121.8? /? After the deposition at 250 占 폚. The Si substrate deposited at 300 캜 had a sheet resistance of 17.95 Ω / □ and a resistance decrease. In addition, the crystal structures of the deposited films were analyzed using Raman and XRD.

7A and 7B show the Raman spectroscopy spectrum according to deposition temperature and substrate. As shown in FIG. 7A, it was confirmed that no thin film was deposited on the Si substrate deposited at 250 ° C, and a cobalt oxide peak and a small a-C peak were confirmed on the Pt substrate. As shown in FIG. 7B, the cobalt oxide peak, the aC peak, and the Si peak were confirmed in the Si substrate deposited at 300 ° C., and the cobalt oxide peak and the aC peak were observed in the Pt substrate in the same manner as in the 250 ° C. deposition .

8 is a spectrum showing the XRD crystal structure in the Pt substrate according to the deposition temperature. As shown in FIG. 8, the thin films deposited at 300 ° C showed Co (101), Co (N (CN) ₂ ) ₂ (111), and Co ₂ N (210). It was confirmed that Co (dpdab) ₂ and NH ₃ of Comparative Example 1 had the same peak as that of the thin film deposited at 300 ° C., and thus the deposition was by thermal decomposition of the precursor. As a result of thermal ALD using Co (dpdab) ₂ , when NH ₃ or H ₂ was used, an ALD reaction occurred at a deposition temperature of 250 ° C., but a thin film containing a large amount of C impurities . When the deposition temperature is 300 ° C, the CVD reaction by pyrolysis can be confirmed. Further, in the deposition temperature of 250 ℃ Co thin film on Pt substrate growth was confirmed that the films deposited using the NH ₃ is thicker than the deposited film using H _2, this Co (dpdab) ₂ reactivity with through NH ₃ was greater than H ₂ . However, it has been confirmed that there is a limitation in depositing a Co thin film having a small amount of impurities using thermal ALD. Therefore, in the embodiments of the present invention, a Co thin film was deposited using a plasma enhanced atomic layer deposition (PEALD) method capable of promoting an ALD deposition reaction using a highly reactive radical.

3. PEALD  Preparation of cobalt-containing thin film used

In this embodiment, Atomic-Premium (CN1 Co, Ltd.), which is an ALD equipment of a direct plasma type, is used to utilize the radical generated by the plasma. For the deposition, Si, SiO ₂ / Si, and Pt / SiO ₂ / Si were cut into a size of 20 mm × 20 mm. The specimens were placed in a loadlock and placed in a chamber. The chamber heater, the showerhead heater, and the side heater were heated to a predetermined temperature to perform this embodiment. In this embodiment, the properties of the deposited films were evaluated by variously changing variables such as Co (dpdab) ₂ supply amount, plasma time, deposition temperature, RF power, and reactive gas.

First, the growth time of Co (dpdab) ₂ was changed after the NH ₃ plasma was fixed, and the ALD growth characteristics of the Co thin film with Co (dpdab) ₂ supplied at 200 ° C were confirmed through sheet resistance. Since the sheet resistance is inversely proportional to the thickness of the thin film, the thickness of the thin film can be roughly predicted through the sheet resistance. 9 shows the sheet resistance values of the deposited thin films while increasing the supply amount of Co (dpdab) _{2 by} fixing the NH ₃ plasma at 200 W for 30 seconds. As shown in Fig. 9, it can be confirmed that the sheet resistance is saturated at 85.5? /? At 20 seconds or more. Assuming that it has the same resistivity, it can be expected that a Co thin film having the same thickness is deposited. Thus, it was confirmed that a self-limiting reaction occurred between the Co precursor and the NH ₃ plasma.

Subsequently, thin film deposition was performed by varying the NH ₃ plasma time (RF power 200 W) at 20 seconds, which is the supply amount of saturated Co (dpdab) ₂ . 10 is a graph showing a change in sheet resistance according to a change in plasma time. As shown in FIG. 10, the plasma resistance showed the lowest sheet resistance value in the range of 5 to 10 seconds, and the sheet resistance was also increased when the plasma time was increased. In order to investigate the reason why the sheet resistance increases with increasing plasma time, the thickness of the Co thin film deposited under the conditions of plasma duration of 10 seconds and 30 seconds was measured by using TEM and analyzed by AES. 11A and 11B are graphs showing the composition and thickness of the thin film when the plasma time is 10 seconds and 30 seconds, respectively. As shown in FIGS. 10, 11A, and 11B, it was confirmed that the thickness of the deposited thin film was thicker at a plasma time of 10 seconds than at a plasma time of 30 seconds. The content of carbon (C) impurity was found to be larger than that of 30 seconds when the plasma time was 10 seconds. These results show that as the plasma time increases, the ions in the plasma collide with the thin film to remove the weakly bound Co or C on the surface of the thin film, thereby lowering the C impurity content of the thin film. However, It is predicted that the resistance is increased due to the occurrence of defects.

Next, the ALD process window was confirmed by fixing the Co (dpdab) ₂ for 20 seconds, the NH ₃ plasma for 30 seconds, and the RF power at 200 W and changing the deposition temperature. 12 is a graph showing the growth rate and resistivity according to the deposition temperature. 13 (a) to 13 (e) are TEM photographs showing the thickness of the deposited thin film according to the deposition temperature under the same conditions. As shown in FIG. 12, an ALD process window showing a growth rate of 0.7 A per cycle at a deposition temperature of 150 ° C to 200 ° C was confirmed. In addition, it was confirmed that the CVD reaction by the thermal decomposition of the cobalt precursor occurred at the deposition temperature of 250 캜 or more. As shown in FIG. 13, it was confirmed that a cobalt-containing film was formed on the surface of the thin film deposited at a deposition temperature of 120 ° C. The cobalt-containing film was analyzed by Raman and found to be cobalt oxide. This means that the film quality of the deposited thin film was poor and reacted with oxygen when exposed to the atmosphere to form cobalt oxide.

Also, as shown in Fig. 14, it was confirmed that the sheet resistance was saturated when the RF power was 100 W or more. The sheet resistance of the thin film deposited at 100 W or more was slightly increased, which is expected to increase the sheet resistance due to the excessive RF power applied to the substrate.

In Fig. 15, changes in the characteristics of the thin film according to the cycle are shown. 15 is a graph showing a change in resistivity and a thickness of a thin film according to the number of cycles. As shown in Fig. 15, it was confirmed that the specific resistance value was extremely high at 50 cycles, and that the resistivity was decreased from 100 cycles. In addition, it was confirmed that the thin film in isolated growth was observed in 50 cycles, and that a continuous thin film was formed in 100 cycles. This indicates that there is a nucleation interval before 100 cycles.

In order to confirm the step coverage characteristics, Co (dadab) ₂ (20 seconds), NH ₃ plasma (200 W, 20 seconds) were formed on a trench pattern wafer having an aspect ratio of 7, 30 seconds), deposition temperature of 200 캜, and 50 cycles. 16 is a TEM photograph of a cobalt-containing thin film deposited on a trench pattern wafer having an aspect ratio of 7. FIG. 16 (d), the thickness of the thin film deposited on the bottom was 6.5 nm, and the thickness of the thin film deposited on the top was 4.1 nm as shown in FIG. 16 (b) Which is 65% step coverage. The reason for this low step coverage is that in the process of entering the trenches and vias due to the plasma generated by the plasma in a structure such as a trench or via, the energy collapses due to the collision of the wall with the radical, The local flow of radicals fed to the bottom of the trench or via decreases as it becomes a nonreactive molecule and moves back into the plasma.

Example  One: PEALD  Preparation of cobalt-containing thin film used 1

The characteristics of the thin film deposition according to the change of the plasma reaction gas were confirmed under the deposition conditions obtained according to the above embodiments. Co (dpdab) ₂ (20 seconds), a plasma (200 W, 30 sec), hold the process conditions of a deposition temperature of 200 ℃, and 200 cycles, respectively by using the NH ₃ and H ₂ the type of plasma gas cobalt- Containing thin films were prepared and compared. 17A and 17B are graphs for AES depth profiling of Co-containing thin films using NH ₃ plasma and H ₂ plasma, respectively. As shown in FIG. 17A, the Co thin film deposited using NH ₃ plasma had a sheet resistance of 29.64? / ?, and the content of C impurity was as low as 4%, but the content of N impurity was as high as 20%. Also, it can be confirmed that the distribution of N decreases toward the inside of the thin film. On the other hand, as shown in FIG. 17B, the Co thin film deposited using the H ₂ plasma had a sheet resistance of 57.45? / ?, which was higher than that of the NH ₃ plasma, and the content of C (carbon) , And a thin film containing a large amount of O (oxygen) impurities was formed. The distribution of the impurities in the cobalt-containing thin film was found to be further increased as the amount of carbon became closer to the inside of the thin film, and it was confirmed that a large amount of oxygen existed on the surface of the thin film. This is due to the oxidation of the film as the deposited film is exposed to the atmosphere. Therefore, it was confirmed that when Co (dadap) ₂ is used as the cobalt precursor, NH ₃ plasma is more advantageous for depositing the Co-containing thin film than the H ₂ plasma.

However, as described above in the present embodiment, the cobalt-containing thin film deposited using the NH ₃ plasma was deposited with the N (nitrogen) -containing thin film, and the distribution of N was not constant but increased toward the surface of the thin film Respectively. As a result, N is not stable in the Co thin film, so it can be expected that N can be removed through heat treatment in a proper atmosphere. Therefore, the composition of the thin film was analyzed by heat treatment at 400 ° C for 30 minutes under an atmosphere of H ₂ to form a Co-containing thin film having a small amount of impurities by removing N. 18 is a graph of AES analysis of the composition before and after the heat treatment at 400 ° C under an H ₂ atmosphere. As shown in FIG. 18, it was confirmed that the N content was 20% before the heat treatment, but the N content was remarkably decreased to 2% or less after the heat treatment, and the other impurities were also low. In addition, the crystal structure was analyzed by XRD to confirm the crystal structure before and after the heat treatment. 19 is an XRD pattern showing the crystal structure of the thin film before and after the heat treatment. The thin film before the heat treatment had no peak as an amorphous structure. However, it was confirmed that it coincided with the Co (111) peak (JCPDS: 89-4308) after the heat treatment. The CoO (100) peak (JCPDS: 89-2803) was confirmed and CoO was generated because the O in the interfacial layer, silicon oxide, was diffused by the heat treatment and reacted with the Co thin film .

This indicates that a Co thin film deposited by an NH ₃ plasma process in the absence of silicon oxide can be subjected to a heat treatment under an H ₂ atmosphere to obtain a high purity thin film having a small amount of impurities. From the above results, it was confirmed that the Co thin film was deposited using NH ₃ plasma to remove the impurity (N) by heat treatment at 400 ° C. for 30 minutes under an H ₂ atmosphere in order to obtain a Co thin film having a small amount of impurities.

Example  2: PEALD  Preparation of used cobalt-containing thin film 2

In this embodiment, a cobalt thin film was prepared by depositing a thin film using NH ₃ and H ₂ mixed gas plasma in order to manufacture a high purity thin film without a separate heat treatment process. 20 is a graph showing sheet resistance and thickness of a thin film deposited under conditions of Co (dpdab) _{2 of} 20 seconds, NH ₃ plasma of 10 seconds, deposition temperature of 200 ° C, and 200 cycles. 21 is a graph showing the compositional change of the thin film according to the change of the kind of the plasma gas. As shown in Fig. 20, 17a, and 21, it exhibited a lower sheet resistance in the as-deposited thin film by using the NH ₃ and H ₂ mixture plasma when compared hayeoteul using the NH ₃ plasma, a thick film is deposited . In addition, the composition analysis also revealed relatively small amounts of C and N impurities.

4. Formation of cobalt suicide

Example  3: Preparation of cobalt silicide thin film

The Co-containing thin film deposited on the Si substrate by the ALD process using the Co (dpdab) ₂ precursor and NH ₃ plasma was heat-treated at 700 ° C. for 1 minute in an RTP apparatus to form cobalt silicide (CoSi ₂ ). 22A and 22B are cross-sectional TEM images of a Co / Si cross section before and after the RTP process, respectively. As shown in Fig. 22A, the cross section of the specimen before heat treatment was confirmed to be a SiO ₂ layer between Co and Si. The specimens were heat treated at 700 ° C for 1 minute with RTP equipment. As shown in FIG. 22B, it was confirmed that the Co thin film in the specimen after heat treatment was agglomeration by heat treatment at a high temperature (700 ° C.). Further, it was confirmed that cobalt suicide partially formed. FIG. 23 shows XRD patterns before and after the RTP process for silicide formation. Only the Co peak was confirmed, and the peak related to CoSi _x was not confirmed. It is presumed that the cobalt suicide partially formed and not confirmed by XRD analysis. In addition, it is expected that if the silicon oxide which interferes with the silicide formation is removed through the above-described results, the cobalt silicide can be formed evenly.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (14)

Cobalt precursor and a first plasma reactive gas to form a cobalt-containing thin film on the substrate; And
The cobalt-containing thin film is heat-treated to remove impurities
Containing thin film.
The cobalt precursor, the first plasma reaction gas, and the second plasma reaction gas alternately to form a cobalt-containing thin film on the substrate
Containing thin film.
3. The method according to claim 1 or 2,
Wherein the cobalt precursor comprises a compound represented by the following formula (1): < EMI ID =
[Chemical Formula 1]

;
In Formula 1,
R ₁ to R ₄ each independently represent a C ₁ to C ₆ linear or branched alkyl group, or an alkyl group which is an isomer thereof.
3. The method according to claim 1 or 2,
The cobalt precursor, _{Co (dpdab) 2, CpCo (} CO) 2, CoCp 2, CCTBA, (2-tert- butyl allyl) cobalt _{tricarbonyl, Co (iPrNCMeNiPr) 2, Co} 2 (CO) 8, Co (C ₅ H ₅₎ (iPrNCMeNiPr), cyclopentadienyl-isopropyl-acetamido Dina soil-preparing a composition containing film-cobalt phosphorus, cobalt comprises is selected from the [Co (CpAMD)], and the group consisting of a combination of Way.
3. The method according to claim 1 or 2,
Wherein the first plasma reactive gas comprises a nitrogen-containing gas; A mixed gas of hydrogen (H ₂ ) gas and nitrogen-containing gas; Or a mixed gas of an inert gas and a nitrogen-containing gas.
6. The method of claim 5,
Wherein the nitrogen-containing gas is NH ₃ , N ₂ , N ₂ H ₄ , N ₂ H _x Me _{4 -x} (x is an integer of 3 or less), R _x NH _{3 -x} (R is a C ₁ to C ₆ alkyl And x is 1 or 2), R _x N ₂ H _{4 -x} (R is a C ₁ to C ₆ alkyl group, x is an integer of 3 or less), and combinations thereof Containing thin film.
3. The method of claim 2,
Wherein the second plasma reactive gas comprises a hydrogen-containing gas; Or a mixed gas of an inert gas and a hydrogen-containing gas.
3. The method according to claim 1 or 2,
Wherein the forming of the cobalt-containing thin film is performed by atomic layer deposition.
3. The method according to claim 1 or 2,
Wherein the forming of the cobalt-containing thin film is performed in a temperature range of 100 ° C to 300 ° C.
The method according to claim 1,
Wherein the heat treatment includes a heat treatment using a plasma.
The method according to claim 1,
Wherein the heat treatment is performed in a temperature range of 100 ° C to 700 ° C.
The method according to claim 1,
Wherein the heat treatment is performed under a hydrogen gas supply.
3. The method according to claim 1 or 2,
Wherein the cobalt-containing thin film has an impurity content of 5% or less.
3. The method according to claim 1 or 2,
Further comprising subjecting the cobalt-containing thin film to further heat treatment to silicidize the cobalt-containing thin film.

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