Patent ID: 12203154

DETAILED DESCRIPTION OF THE DISCLOSURE

The embodiments will be described in detail herein with reference to the drawings.

However, it should be understood that the present disclosure is not limited to the embodiments according to the concept of the present disclosure, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present disclosure.

In the following description of the present disclosure, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure unclear.

The terms used in the specification are defined in consideration of functions used in the present disclosure, and can be changed according to the intent or conventionally used methods of clients, operators, and users. Accordingly, definitions of the terms should be understood on the basis of the entire description of the present specification.

In description of the drawings, like reference numerals may be used for similar elements.

The singular expressions in the present specification may encompass plural expressions unless clearly specified otherwise in context.

In this specification, expressions such as “A or B” and “at least one of A and/or B” may include all possible combinations of the items listed together.

Expressions such as “first” and “second” may be used to qualify the elements irrespective of order or importance, and are used to distinguish one element from another and do not limit the elements.

It will be understood that when an element (e.g., first) is referred to as being “connected to” or “coupled to” another element (e.g., second), it may be directly connected or coupled to the other element or an intervening element (e.g., third) may be present.

As used herein, “configured to” may be used interchangeably with, for example, “suitable for”, “ability to”, “changed to”, “made to”, “capable of”, or “designed to” in terms of hardware or software.

In some situations, the expression “device configured to” may mean that the device “may do ˜” with other devices or components.

For example, in the sentence “processor configured to perform A, B, and C”, the processor may refer to a general purpose processor (e.g., CPU or application processor) capable of performing corresponding operation by running a dedicated processor (e.g., embedded processor) for performing the corresponding operation, or one or more software programs stored in a memory device.

In addition, the expression “or” means “inclusive or” rather than “exclusive or”.

That is, unless otherwise mentioned or clearly inferred from context, the expression “x uses a or b” means any one of natural inclusive permutations.

In the above-described specific embodiments, elements included in the invention are expressed singular or plural in accordance with the specific embodiments shown.

It should be understood, however, that the singular or plural representations are to be chosen as appropriate to the situation presented for the purpose of description and that the above-described embodiments are not limited to the singular or plural constituent elements. The constituent elements expressed in plural may be composed of a single number, and constituent elements expressed in singular form may be composed of a plurality of elements.

In addition, the present disclosure has been described with reference to exemplary embodiments, but it should be understood that various modifications may be made without departing from the scope of the present disclosure.

Therefore, the scope of the present disclosure should not be limited by the embodiments, but should be determined by the following claims and equivalents to the following claims.

FIG.1illustrates cobalt-tungsten alloy nanowires according to an embodiment.

Referring toFIG.1, the cobalt-tungsten alloy nanowires according to an embodiment are formed by an electroplating method, thereby having an amorphous structure and relatively low electrical resistivity.

In addition, the cobalt-tungsten alloy nanowires according to an embodiment serve as a barrier for preventing diffusion into a low-k dielectric of metal wiring and a liner for metal wiring plating, thereby being used as a single layer in a metal wiring process.

In particular, the cobalt-tungsten alloy nanowires100according to an embodiment may be formed using an electroplating method, a grain structure thereof may be controlled according to the content of tungsten, and electrical resistivity may be reduced through annealing.

According to an embodiment, in the case of the cobalt-tungsten alloy nanowires100, a cobalt-tungsten intermetallic compound may be formed through annealing, thereby reducing electrical resistivity.

According to an embodiment, intermetallic compounds may appear at 2θ of 40.700±0.3°, 43.880±0.3° and 46.460±0.3° when analyzing X-ray diffraction (XRD). Here, intermetallic compounds may correspond to XRD peak positions derived during XRD analysis.

The intermetallic compounds of the cobalt-tungsten alloy nanowires100according to an embodiment will be described in detail below with reference toFIG.6.

According to an embodiment, annealing may be performed at 25° C. to 600° C. For example, cobalt-tungsten alloy nanowires may be annealed and formed at a temperature of less than 600° C. when used as a barrier, and may be annealed and formed at 600° C. when used as a liner.

According to an embodiment, a grain structure of the cobalt-tungsten alloy nanowires100may be controlled to have an amorphous-like structure when the content of tungsten is 25.1 at. %.

In addition, a grain structure of the cobalt-tungsten alloy nanowires100may be controlled to have a mixed structure including an amorphous-like structure and a polycrystalline structure when the content of tungsten is 15.8 at. % to 19.1 at. %.

Here, since a grain size of the amorphous-like structure is formed as small as that of an amorphous structure, the amorphous-like structure may be a nano-crystalline structure exhibiting the same characteristics as an amorphous structure.

According to an embodiment, in the case of the cobalt-tungsten alloy nanowires100, at least one of a tungsten precursor concentration and a current density may be controlled to control the content of tungsten.

For example, the cobalt-tungsten alloy nanowires100may be formed by an electroplating method using a deionized water-based solution including cobalt sulfate heptahydrate (CoSO4·7H2O) and sodium tungstate heptahydrate (Na2WO4·7H2O) which are precursors.

In addition, the deionized water-based solution may further include boric acid (H3BO3) and citric acid (C6H8O7) as buffers; and sodium citrate tribasic dihydrate (C6H7Na3O8) as an additive.

The cobalt-tungsten alloy nanowires according to an embodiment will be described in more detail below with reference toFIGS.2to7.

FIG.2illustrates a method of fabricating cobalt-tungsten alloy nanowires according to an embodiment.

In other words,FIG.2illustrates a method of fabricating the cobalt-tungsten alloy nanowires according to the embodiment described with reference toFIG.1, and thus, contents described inFIG.1are omitted in describingFIG.2.

Referring toFIG.2, the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment uses an electroplating method, thereby being capable of providing cobalt-tungsten alloy nanowires having an amorphous structure and low electrical resistivity.

In addition, the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment may provide cobalt-tungsten alloy nanowires that serve as a barrier for preventing diffusion into a low-k dielectric of metal wiring and a liner for metal wiring plating and thus is capable of being used as a single layer in a metal wiring process.

Recently, research and development of a new process using scaling boosters and various materials has been actively conducted, among which a cobalt (Co)-based alloy-based single layer has been identified as a promising material that can replace a TaN/Ta double layer structure having a high specific resistance value.

Accordingly, the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment employs a single layer-alloying approach to replace an existing double layer structure. The single layer-alloying approach allows realization of an amorphous structure or a grain stuffing effect, thereby being capable of improving barrier properties. In addition, the amorphous structure allows removal of diffusion paths through grain boundaries, thereby being capable of exhibiting excellent anti-diffusion properties.

In addition, the single-layer alloy material of the cobalt-tungsten alloy nanowires according to an embodiment may have a lower electrical resistivity value than nitride (TaN, resistivity: 160-400 μΩ·cm) while reducing interface resistance caused by a multi-layer structure.

According toFIG.2, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, cobalt-tungsten (Co—W) alloy nanowires may be formed on a nanotemplate using an electroplating method.

For example, the cobalt-tungsten alloy nanowires formed using an electroplating method may be represented by Co100-xWx, where the content x of tungsten may be 0 at. %<x≤25.1 at. %.

In addition, the nanotemplate may include a polycarbonate membrane (PCM) or anodic aluminum oxide (AAO), and at least one nano-porous track may be formed therein. Here, the nano-porous track may be a region where cobalt-tungsten alloy nanowires are deposited through electroplating.

According to an embodiment, in step210of the method of fabricating cobalt-tungsten alloy nanowires, cobalt-tungsten alloy nanowires may be formed on the nanotemplate by an electroplating method using a deionized water-based solution including cobalt sulfate heptahydrate (CoSO4·7H2O; 0.20 M) and sodium tungstate heptahydrate (Na2WO4·7H2O; 0.10 or 0.20 M) which are precursors.

In addition, a deionized water-based solution may further include boric acid (H3BO3; 0.65 M) and citric acid (C6H8O7; 0.04 M), which are buffers, and sodium citrate tribasic dihydrate (C6H7Na3O8; 0.25 or 0.50 M) which is an additive.

Meanwhile, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, a grain structure of the alloy nanowires may be controlled according to the content of tungsten.

According to an embodiment, in step210of the method of fabricating cobalt-tungsten alloy nanowires, the grain structure of the alloy nanowires may be controlled to have an amorphous-like structure by controlling the content of tungsten to 25.1 at. %.

In addition, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the grain structure of the alloy nanowires may be controlled to have a mixed structure including an amorphous-like structure and a polycrystalline structure by controlling the content of tungsten to 15.8 at. % to 19.1 at. %.

Preferably, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the grain structure of the alloy nanowires may be controlled to have an amorphous-like structure by controlling the content of tungsten to 25.1 at. %.

That is, by the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, cobalt-tungsten alloy nanowires having an amorphous structure may be formed by controlling the content of tungsten.

According to an embodiment, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the content of tungsten may be controlled by controlling at least one of a tungsten precursor concentration and a current density.

In other words, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the content of tungsten may be controlled by controlling the concentration of a tungsten precursor solution and a current density in a process of forming cobalt-tungsten alloy nanowires using an electroplating method.

For example, in step210of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, cobalt-tungsten alloy nanowires may be formed using an electroplating method in an environment in which a current density of 1.25 mA/cm2to 5.00 mA/cm2is applied to simultaneously reduce cobalt and tungsten.

In step220of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the formed alloy nanowires may be annealed.

According to an embodiment, in step220of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the formed alloy nanowires may be separated from the nanotemplate, and the separated alloy nanowires may be annealed.

According to an embodiment, in step220of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, a cobalt-tungsten intermetallic compound may be formed through annealing, thereby reducing electrical resistivity of the formed alloy nanowires.

According to an embodiment, in step220of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the formed alloy nanowires may be annealed at 25° C. to 600° C., preferably at 600° C.

That is, in the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the cobalt-tungsten alloy nanowires formed to have an amorphous structure may be annealed, thereby reducing electrical resistivity of the cobalt-tungsten alloy nanowires having an amorphous structure.

Meanwhile, the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment may further include a step of forming a nanotemplate.

More particularly, in the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, at least one nano-porous track may be formed on a template material and a working electrode layer may be formed on one side surface of the template material on which the nano-porous track has been formed, so as to form a nanotemplate.

For example, the nanotemplate includes a polycarbonate membrane or anodic aluminum oxide, and the working electrode layer may be at least one of a silver (Ag) electrode and a gold (Au) electrode, preferably may be realized using a silver (Ag) electrode.

According to an embodiment, the anodic aluminum oxide may be a porous substrate prepared by oxidizing aluminum using a predetermined acidic solution, and the working electrode layer may be deposited on the polycarbonate membrane or the anodic aluminum oxide using an e-beam evaporator.

FIGS.3A to3Dillustrate an example of a method of fabricating cobalt-tungsten alloy nanowires according to an embodiment.

In other words,FIGS.3A to3Dillustrate an example of a method of fabricating the cobalt-tungsten alloy nanowires according to the embodiment described with reference toFIG.2, and thus, contents described inFIG.2are omitted in describingFIGS.3A to3D.

Referring toFIGS.3A to3D, in step310of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, a template material311may be formed to have at least one nano-porous track to form nanotemplates311and321.

For example, the nanotemplates311and321may include a polycarbonate membrane (PCM) or anodic aluminum oxide (AAO).

In addition, in step310of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, regions, in which cobalt-tungsten (Co—W) alloy nanowires331are to be formed, of the template material311are etched, thereby forming nano-porous tracks.

In step320of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, a working electrode layer321is formed on one side surface of the template material311in which nano-porous tracks have been formed, thereby completing the nanotemplates311and321.

For example, in step320of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, silver (Ag) may be deposited to a thickness of 300 nm on one side surface of the template material311, in which nano-porous tracks have been formed, using an e-beam evaporator.

Here, the deposited silver (Ag) may be used as a working electrode to perform an electroplating method, and a platinum (Pt) electrode plate may be used as a counter electrode.

In step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, cobalt-tungsten alloy nanowires331may be formed on the nanotemplates311and321using an electroplating method.

For example, in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the cobalt-tungsten alloy nanowires331may be formed on the nanotemplates311and321by an electroplating method in which a deionized water-based solution including cobalt sulfate heptahydrate (CoSO4·7H2O; 0.20 M) and sodium tungstate heptahydrate (Na2WO4·7H2O; 0.10 or 0.20 M) which are precursors is used.

In addition, the deionized water-based solution may further include boric acid (H3BO3; 0.65 M) and citric acid (C6H8O7; 0.04 M), which are buffers, and sodium citrate tribasic dihydrate (C6H7Na3O8; 0.25 or 0.50 M) which is an additive.

In addition, in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, a current density of 1.25 mA/cm2to 5.00 mA/cm2may be applied to simultaneously reduce cobalt and tungsten.

Meanwhile, in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the grain structure of the alloy nanowires may be controlled according to the content of tungsten.

According to an embodiment, in step330of the method of fabricating cobalt-tungsten alloy nanowires, the grain structure of the alloy nanowires may be controlled to have an amorphous-like structure when the content of tungsten is 25.1 at. %.

In addition, in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the grain structure of the alloy nanowires may be controlled to have a mixed structure including an amorphous-like structure and a polycrystalline structure when the content of tungsten is 15.8 at. % to 19.1 at. %.

According to an embodiment, in step330of the method of fabricating cobalt-tungsten alloy nanowires, the content of tungsten may be controlled by adjusting at least one of a tungsten precursor concentration and a current density.

Preferably, in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the content of tungsten may be controlled by adjusting both the deionized water-based solution including a tungsten precursor and a current density.

In particular, according to the following Table 1 in which synthesis conditions by cobalt-tungsten composition are summarized, the content of tungsten may be controlled by adjusting the concentrations of sodium tungstate heptahydrate (Na2WO4·7H2O), as a tungsten precursor material, and sodium citrate tribasic dihydrate (C6H7Na3O8), as an additive, and a current density in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment.

TABLE 1Experimental conditionsNa2WO4C6H7Na3O8Current densityW-content(mol L−1)(mol L−1)(mA/cm2)(at. %)0.000.001.250.00.100.251.253.50.100.255.007.50.100.501.258.50.100.505.0015.80.200.501.2519.10.200.505.0025.1

Preferably, in step330of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the content of tungsten may be controlled to 25.1 at. % by adjusting the concentration of sodium tungstate heptahydrate (Na2WO4·7H2O) to 0.20 mol L−1, by adjusting the concentration of sodium citrate tribasic dihydrate (C6H7Na3O8) to 0.50 mol L−1, and by adjusting a current density to 5.00 mA/cm2. Accordingly, the grain structure of the cobalt-tungsten alloy nanowires may be controlled to have an amorphous-like structure.

In step340of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the alloy nanowires331may be separated from the nanotemplates311and321.

For example, in step340of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, a working electrode321may be removed with an adhesive tape, and the template material311including the alloy nanowires331may be selectively removed with a dichloromethane solution (CH2Cl2), followed by washing with a chloroform solution (CHCl3) and acetone five or more times through a centrifuge. As a result, the alloy nanowires331present inside the template material311may be separated.

According to an embodiment, in step340of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the template material311may be selectively removed by stirring for about 15 minutes using 3 M sodium hydroxide (NaOH).

In step340of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the separated alloy nanowires331may be annealed.

According to an embodiment, in step340of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the formed alloy nanowires may be annealed at 25° C. to 600° C.

Preferably, in step340of the method of fabricating cobalt-tungsten alloy nanowires according to an embodiment, the alloy nanowires331may be annealed at 600° C.

FIGS.4A to4Hillustrates HRTEM and SAED images of cobalt-tungsten alloy nanowires according to an embodiment.

FIGS.4A to4Hillustrate high-resolution transmission electron microscope (HRTEM) images and selected-area electron diffraction (SAED) images of cobalt-tungsten alloy nanowires with a diameter of 130 nm formed using various tungsten contents.

In particular,FIGS.4A and4Billustrate images of cobalt nanowires in which the content of tungsten is 0.0 at. %,FIGS.4C and4Dillustrate images of cobalt-tungsten alloy nanowires in which the content of tungsten is 3.5 at. %,FIGS.4E and4Fillustrate images of cobalt-tungsten alloy nanowires in which the content of tungsten is 7.5 at. %, andFIGS.4G and4Hillustrate images of cobalt-tungsten alloy nanowires in which the content of tungsten is 25.1 at. %.

FromFIGS.4A to4H, it can be confirmed that, as a tungsten content in the cobalt-tungsten alloy nanowires increases, interatomic spacing increases and amorphous nanowires are synthesized.

More particularly, from SAED images ofFIGS.4C,4E and4G, it can be confirmed that the cobalt-tungsten alloy nanowires in which the content of tungsten is 3.5 at % have a polycrystalline structure and thus have lower crystallinity and smaller particle size than pure cobalt nanowires, and the cobalt-tungsten alloy nanowires in which the content of tungsten reaches 15.8 at % have both a nano-crystalline structure (amorphous-like structure) and a polycrystalline structure.

In addition, the cobalt-tungsten alloy nanowires in which the content of tungsten reaches 15.8 at % exhibit a blurry ring pattern as shown inFIG.4G, which indicates that the nanowires have a nano-crystalline structure (amorphous-like structure) and thus are amorphous.

FIGS.5A to5Dillustrates XRD analysis results of cobalt-tungsten alloy nanowires according to an embodiment.

Referring toFIGS.5A to5D,FIG.5Aillustrates an x-ray diffraction (XRD) pattern of cobalt-tungsten alloy nanowires,FIG.5Billustrates peak position changes dependent upon tungsten content changes in cobalt-tungsten alloy nanowires,FIG.5Cillustrates (002) interplanar distance changes dependent upon tungsten content changes in cobalt-tungsten alloy nanowires, andFIG.5Dillustrates grain size changes, which are derived from XRD analysis, dependent upon tungsten content changes in cobalt-tungsten alloy nanowires.

FromFIG.5A, it can be confirmed that both the cobalt-tungsten alloy nanowires according to an embodiment and pure cobalt nanowires have an hcp structure.

In particular, it can be confirmed that the pure cobalt nanowires exhibit a crystalline hcp structure and a strong hcp (002) texture, and the cobalt-tungsten alloy nanowires according to an embodiment exhibit a crystalline hcp structure, similar to the pure cobalt nanowires, and an hcp (002) texture until the content of tungsten increases to 8.5 at %.

In addition, it can be confirmed that the 20 value of the cobalt-tungsten alloy nanowires according to an embodiment changes in response to changes in the tungsten content when the content of tungsten changes within a range of 3.5 at % to 8.5 at %.

The shift of an XRD peak position of the cobalt-tungsten alloy nanowires according to an embodiment may occur as a result of incorporating tungsten into a cobalt lattice and forming a substitution alloy.

An average distance (davg) between two adjacent atoms may be derived from the following Equation 1:
davg=2[rCo+(rW−rCo)·Xw]  [Equation 1]

wherein rcoand rwrespectively represent the radii of cobalt and tungsten atoms, and Xwrepresents an atomic fraction of tungsten.

In addition, a peak position of XRD may be derived from the Bragg equation of the following Equation 2:

davg=λ2⁢sin⁢θ[Equation⁢2]

wherein 2θ represents a peak position, and λ represents Cu Kα wavelength.

When tungsten composed of larger atoms enters cobalt which is a host element, significant stress is generated around the host element, which greatly affects electrical properties. In particular, as the content of introduced tungsten (the number of atoms) increases, an average distance (davg) may increase when a substituted cobalt-tungsten alloy is formed.

In other words, in the case of the cobalt-tungsten alloy nanowires according to an embodiment, it can be confirmed that, as the number of introduced tungsten atoms increases, an average distance (davg) between two adjacent atoms increases when a substituted cobalt-tungsten alloy is formed, resulting in movement of the XRD peak position to a smaller angle.

Referring toFIG.5B, diffraction peaks of hcp Co(W) (002) are observed at 44.5°, 44.3°, 44.1° and 44° at tungsten contents of 0.0 at %, 3.5 at %, 7.5 at % and 8.5 at %, respectively.

Referring toFIG.5C, it can be confirmed that the interplanar distance d(002) calculated from the XRD pattern linearly increases with increasing content of tungsten, and the increased d(002) value may indicate an increase in electrical resistivity.

FIG.5Dillustrates grain sizes calculated using the Scherrer equation. FromFIG.5D, it can be confirmed that a grain size of the cobalt-tungsten alloy nanowires according to an embodiment is 38.2 nm when the content of cobalt is 0 at. %, and the grain size is reduced with increasing content of tungsten. Meanwhile, the cobalt-tungsten alloy nanowires according to an embodiment may exhibit an amorphous-like structure when the grain size is smaller than 5 nm.

That is, it can be confirmed that the grain size of the cobalt-tungsten alloy nanowires according to an embodiment is reduced with increasing content of tungsten. Particularly, it can be confirmed that, when the content of tungsten is 25.1 at. %, the grain size is reduced to 4 nm or less and thus an amorphous-like structure (nano-crystalline structure) is exhibited.

FIGS.6A to6Eillustrates annealing temperature-dependent crystallinity characteristic changes of cobalt-tungsten alloy nanowires according to an embodiment.

Referring toFIGS.6A to6E,FIG.6Aillustrates annealing temperature-dependent XRD analysis results of the cobalt-tungsten alloy nanowires when the content of tungsten is 25.1 at. %, andFIGS.6B to6Eillustrate SAED patterns of the cobalt-tungsten alloy nanowires when annealing is nor performed, when annealing is performed at 400° C., when annealing is performed at 500° C. and annealing is performed at 600° C.

Referring toFIG.6A, cobalt-tungsten intermetallic compounds may be formed and thus electrical resistivity may be reduced when the cobalt-tungsten alloy nanowires according to an embodiment are annealed at 600° C. Here, the intermetallic compounds may correspond to an XRD peak position.

Here, the intermetallic compounds may be observed at 2θ of 40.70°±0.3°, 43.88°±0.3° and 46.46°±0.3°.

More particularly, it can be confirmed that, when the cobalt-tungsten alloy nanowires according to an embodiment are annealed at 400° C., a single broad XRD peak and a nano-crystalline structure having reduced crystallinity are observed.

On the other hand, when the cobalt-tungsten alloy nanowires according to an embodiment are annealed at 600° C., crystallization of the Co3W phase occurs and diffraction patterns of polycrystalline hcp Co3W are observed, and crystallinity is significantly improved.

In addition, it can be confirmed that, when the cobalt-tungsten alloy nanowires according to an embodiment are annealed at 600° C., a grain size significantly increases to 19.7 nm. This means that Co3W alloy nanowires are formed after a deposited state present in a solid dissolution state is subjected to heat treatment, which contributes to reduction of internal stress and low resistivity.

Annealing temperature-dependent grain sizes and microstrains of the cobalt-tungsten alloy nanowires may be derived as in the following Table 2.

TABLE 2AnnealingGrain size,Microstrain,temperature (° C.)D (nm)ε (×10−2)As-deposited2.244.124002.943.125003.772.4360019.70.54

FromFIGS.6A to6Eand Table 2, it can be confirmed that annealing temperature-dependent electrical resistivity changes of the cobalt-tungsten alloy nanowires according to an embodiment are inversely proportional to grain sizes.

In particular, it can be confirmed fromFIG.7Ddescribed below that resistivity values of the cobalt-tungsten alloy nanowires according to an embodiment are reduced to 128.0 μΩ·cm and 120.0 μΩ·cm after being annealed at 400° C. and 500° C., and a resistivity value is significantly reduced to 87.5 μΩ·cm after being annealed at 600° C. Such resistivity value reduction after annealing may be caused by a grain size increase and release of residual stress.

In addition, it can be confirmed that the microstrain of the cobalt-tungsten alloy nanowires according to an embodiment is also significantly reduced from 4.12 (10−2) to 0.54(10−2).

FIGS.7A to7Dillustrates electrical property changes dependent upon compositions, nanowire diameters and annealing temperature of cobalt-tungsten alloy nanowires according to an embodiment.

Referring toFIGS.7A to7D,FIG.7Aillustrates a current (I)-voltage (V) curve of cobalt-tungsten alloy nanowires in which the content of tungsten is 3.5 at. %,FIG.7Billustrates a tungsten content change-dependent electrical resistivity change in cobalt-tungsten alloy nanowires,FIG.7Cillustrates diameter change-dependent electrical resistivity changes in cobalt-tungsten alloy nanowires in which the contents of tungsten are respectively 0.0 at. %, 7.5 at. % and 25.1 at. %, andFIG.7Dillustrates an annealing temperature change-dependent electrical resistivity change in cobalt-tungsten alloy nanowires in which the content of tungsten is 25.1 at. %.

As shown inFIG.7A, the current of the cobalt-tungsten alloy nanowires linearly increases according to voltage, and a resistivity value calculated through the I-V curve was 81 μΩ·cm.

In addition, fromFIG.7B, it can be confirmed that the cobalt-tungsten alloy nanowires in which the content of cobalt is 0 at. % exhibits a resistivity value of 9.4 μΩ·cm, the cobalt-tungsten alloy nanowires in which the content of cobalt is 3.5 at. % exhibits a rapidly increased resistivity value of 72.3 μΩ·cm, and a resistivity value increases up to 133.8 μΩ·cm when the content of cobalt finally increases up to 25.1 at. %.

That is, the resistivity value of the cobalt-tungsten alloy nanowires tends to continuously increase with increasing content of tungsten. However, the highest resistivity value thereof is confirmed to be lower than that of a TaN material (160 μΩ·cm to 400 μΩ·cm).

FromFIG.7C, it can be confirmed that the resistivity of the cobalt-tungsten alloy nanowires according to an embodiment increases with decreasing diameter thereof regardless of the tungsten content. In particular, it can be confirmed that the resistivity value increases to 170 μΩ·cm when the content of tungsten is 25.1 at. % and the diameter is 30 nm.

However, it can be confirmed that the cobalt-tungsten alloy nanowires according to an embodiment have still a lower resistivity value than that of a TaN material (500 μΩ·cm to 1,000 μΩ·cm; thickness: 30 nm).

FromFIG.7D, it can be confirmed that the resistivity value of the cobalt-tungsten alloy nanowires according to an embodiment gradually decreases as an annealing temperature increases up to 500° C., and the resistivity value is significantly reduced from 120.0 μΩ·cm to 87.5 μΩ·cm when heat-treated at 600° C.

FIGS.8A to8Cillustrates an application example of cobalt-tungsten alloy nanowires according to an embodiment.

Referring toFIGS.8A to8C,FIG.8Aillustrates a semiconductor device800including a back end of line (BEOL) layer and a front end of line (FEOL) layer,FIG.8Billustrates a metal line810and via820included in the BEOL layer of the semiconductor device800, andFIG.8Cillustrates a metal line810including a metal layer811, a liner812, a barrier813and a dielectric814.

For example, devices denoted by reference numeral830illustrated inFIG.8Bmay be transistor elements, and the metal layer811may include at least one metal of copper, cobalt and tungsten.

In particular, the cobalt-tungsten alloy nanowires according to an embodiment may be applied in the form of at least one of a barrier and a liner with respect to at least one of the metal line810, via820and contact included in the BEOL layer of the semiconductor device800.

For example, the cobalt-tungsten alloy nanowires according to an embodiment may be applied in the form of the liner812and barrier813formed on the metal layer811of the metal line810.

In other words, the cobalt-tungsten alloy nanowires according to an embodiment may replace a conventional Ta liner and TaN barrier formed on copper metal wiring, thereby preventing rapid resistance increase in the copper metal wiring and thus reducing the thickness of a barrier/liner bilayer.

In conclusion, the present disclosure provides cobalt-tungsten alloy nanowires having an amorphous structure and low electrical resistivity using an electroplating method.

In addition, the present disclosure provides cobalt-tungsten alloy nanowires that serve as a barrier for preventing diffusion into a low-k dielectric of metal wiring and a liner for metal wiring plating and, accordingly, are used in the form of a single layer in a metal wiring process.

In accordance with an embodiment, the present disclosure can provide cobalt-tungsten alloy nanowires having an amorphous structure and low electrical resistivity using an electroplating method.

In addition, the present disclosure can provide cobalt-tungsten alloy nanowires that serve as a barrier for preventing diffusion into a low-k dielectric of metal wiring and a liner for metal wiring plating and, accordingly, are used in the form of a single layer in a metal wiring process.

Although the present disclosure has been described with reference to limited embodiments and drawings, it should be understood by those skilled in the art that various changes and modifications may be made therein. For example, the described techniques may be performed in a different order than the described methods, and/or components of the described systems, structures, devices, circuits, etc., may be combined in a manner that is different from the described method, or appropriate results may be achieved even if replaced by other components or equivalents.

Therefore, other embodiments, other examples, and equivalents to the claims are within the scope of the following claims.