Methods for forming a metallic film on a substrate by cyclical deposition and related semiconductor device structures

Parties to the Joint Research Agreement The invention claimed in this application was made by, for, and/or in connection with a Joint Research Agreement between the University of Helsinki and ASM Microchemistry Oy, which was in effect on or before the date the claimed invention was made, and which was made as a result of activities undertaken within the scope of the Agreement.

The present disclosure relates generally to a method for forming a metallic film on a substrate by cyclic deposition, in particular a metallic film comprising at least one of copper, cobalt, and nickel. The present disclosure also relates to a semiconductor device structure including a metallic film formed by cyclic deposition.

Related Art Metallic films, such as metallic films containing copper, cobalt, and nickel, can be utilized in the fabrication of semiconductor device structures. For example, copper has become a primary interconnect material for microelectronic devices due to the low resistivity and high electromigration resistance that copper films exhibit. Copper interconnects can be fabricated by a two-step process in which a copper seed layer is first formed by physical vapor deposition (PVD), followed by a subsequent copper fill process by an electrodeposition process. However, the development of next generation microelectronic devices depends on the shrinking feature sizes of semiconductor devices. Thus, the copper seed layer may be required to be an extremely thin film that not only exhibits low resistivity, but can also be conformally formed.

Due to the inherent conformal limitations of PVD techniques, there is a need for more suitable deposition processes to conformally deposit metallic films for use in the fabrication of semiconductor device structures, such as for forming copper seed layers. Cyclic deposition, e.g., atomic layer deposition processes, can be used to conformally form metallic films by alternating the delivery of two or more gaseous precursors for reaction at the surface of a substrate. The reaction steps that make up the atomic layer deposition process, which can deposit uniform, conformal metallic films with atomic precision, can be self-limiting.

As an example, the cyclic deposition of copper for the fabrication of semiconductor device structures has been studied, using copper chloride (CuCl), zinc (Zn) and hydrogen (H₂) are available. However, deposition of high quality copper films at low temperatures has proven to be a challenging problem. Cyclic deposition, such as atomic layer deposition processes, which suppress agglomeration and allow deposition of thin continuous films of copper, can utilize lower deposition temperatures. However, most copper ALD processes require high temperature deposition techniques, and low temperature processes, primarily achieved by plasma enhanced processes, can result in substrate degradation and poorly conformal coatings.

Therefore, methods and semiconductor device structures that can deposit metallic films at low deposition temperatures and in which the deposition process can provide high quality, conformal metallic films are desirable.

This Summary is provided to introduce a selection of concepts in a simplified form that are described in more detail below in the Detailed Description of Exemplary Embodiments of the Disclosure. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

In some embodiments, a method of forming a metallic film on a substrate by cyclic deposition is provided, the method comprising contacting the substrate with a first reactant comprising a halogen-free metal precursor comprising at least one of copper, nickel, or cobalt, and contacting the substrate with a second reactant comprising a hydrocarbon-substituted hydrazine precursor.

While the specification particularly points out, distinctly claims and concludes what are regarded as embodiments of the present disclosure, the advantages of the disclosed embodiments may be more readily ascertained from a description of several examples of the disclosed embodiments when read in conjunction with the accompanying drawings, in which:<figref num="1">1 is a graph showing an X-ray diffraction (XRD) scan of a copper film formed in accordance with an embodiment of the present disclosure.</figref><figref num="2">1 is a simplified cross-sectional view of a semiconductor device structure formed in accordance with an embodiment of the present disclosure.</figref><figref num="3">FIG. 1 illustrates a reaction system configured to implement some embodiments of the present disclosure.</figref><figref num="4">1 is a graph showing time-of-flight elastic recoil detection analysis (TOF-ERDA) of a copper film formed according to an embodiment of the present disclosure.</figref>

The illustrations shown herein are not meant to be actual illustrations of any particular materials, structures, or devices, but merely idealized representations used to explain embodiments of the present disclosure.

As used herein, the term "cyclic deposition" refers to the sequential introduction of precursors (reactants) into a reaction chamber to deposit layers on a substrate, and includes processing techniques such as atomic layer deposition and cyclic chemical vapor deposition.

The term "atomic layer deposition" (ALD) as used herein can refer to a vapor deposition process in which a deposition cycle, preferably multiple consecutive deposition cycles, are performed in a process chamber. Typically, during each cycle, a precursor chemisorbs to a deposition surface (e.g., the surface of a substrate or a surface of a previously deposited underlayer, such as a material deposited using a previous ALD cycle) and forms a monolayer or submonolayer that does not readily react with additional precursors (i.e., a self-limiting reaction). If necessary, a reactant (e.g., another precursor or a reactant gas) can then be introduced into the process chamber for use in converting the chemisorbed precursor to a desired material on the deposition surface. Typically, this reactant can further react with the precursor. Additionally, a purge step can be utilized during each cycle to remove excess precursor from the process chamber after conversion of the chemisorbed precursor and/or to remove excess reactants and/or reaction by-products from the process chamber. Additionally, the term "atomic layer deposition" as used herein is also meant to include processes denoted by related terms, such as, for example, "chemical vapor deposition atomic layer deposition," "atomic layer epitaxy" (ALE), molecular beam epitaxy (MBE), gas source MBE, or metalorganic MBE, as well as chemical beam epitaxy when performed with alternating pulses of precursor compositions, reactive gases, and purge (e.g., inert carrier) gases.

As used herein, the term "cyclic chemical vapor deposition" can refer to any process in which a substrate is sequentially exposed to two or more volatile precursors that react and/or decompose on the substrate to produce a desired deposit.

As used herein, the term "substrate" can refer to any underlying material or materials that can be used or upon which a device, circuit or film can be formed.

As used herein, the term "hydrocarbon-substituted hydrazine" refers to a hydrazine (N₂H₄) may refer to a derivative of

As used herein, the term "halogen-free metal precursor" can refer to a metal precursor that is substantially free of halogen species.

The present disclosure includes methods of forming metallic films on substrates by cyclic deposition processes, and the semiconductor device structures themselves that include metallic films formed by cyclic deposition processes. The disclosed methods may include methods of cyclic deposition of metallic films, such as copper, cobalt, and nickel. The disclosure may also include utilizing metallic films, such as copper, as at least a portion of a metallic interconnect. The disclosure may also include methods of forming metallic films with reduced electrical resistivity and desirable crystallographic properties. Examples of such methods and semiconductor device structures are disclosed in more detail below.

Non-limiting exemplary embodiments of cyclic deposition processes include ALD, which is based on a typical self-limiting reaction whereby sequential and alternating pulses of reactants are used to deposit approximately one atomic (or molecular) monolayer of material per deposition cycle. Deposition conditions and precursors are typically selected to provide a self-saturating reaction such that an adsorbed layer of one reactant leaves a surface termination unreactive with the gas phase reactant of the same reactant. The substrate is then contacted with a different reactant that reacts with the previous termination, allowing for successive depositions. Thus, each cycle of alternating pulses typically leaves approximately one or less monolayers of the desired material. However, as noted above, one skilled in the art will recognize that more than one monolayer of material can be deposited in one or more ALD cycles, for example, if several gas phase reactions occur despite the alternating nature of the process.

In an ALD-type process for depositing a metallic film, one deposition cycle can include exposing a substrate to a first reactant, removing any unreacted first reactant and reaction by-products from the reaction space, and exposing the substrate to a second reactant, followed by a second removing step. The first reactant can include a halogen-free metal precursor and the second reactant can include a hydrocarbon-substituted hydrazine precursor.

The precursors are doped with argon (Ar) or nitrogen (N) to prevent gas-phase reactions between the reactants and to allow self-saturating surface reactions.₂) can be separated. However, in some embodiments, the substrate can be moved to contact the first and second gas phase reactants separately. Since the reaction is self-saturating, strict temperature control of the substrate and precise dosage control of the precursors are not usually necessary. However, the substrate temperature is preferably such that the incident gas species do not condense into a monolayer and do not decompose at the surface. Before contacting the substrate with the next reactive chemical, excess chemicals and reaction by-products, if any, are removed from the substrate surface, for example by purging the reaction space or by moving the substrate. Undesired gas molecules can be effectively evacuated from the reaction space with an inert purge gas. A vacuum pump can be used to facilitate purging.

According to some embodiments, ALD processes are used to form metallic films on substrates, such as integrated circuit workpieces. In some embodiments of the present disclosure, each ALD cycle includes two distinct deposition steps or phases. In a first phase of the deposition cycle (the "metal phase"), the surface of the substrate on which deposition is desired is contacted with a first gas-phase reactant that includes a metal precursor that chemisorbs onto the surface of the substrate and forms about one or less monolayers of the reactant species on the surface of the substrate.

Any reactor that can be used to grow thin films can be used for deposition. Such reactors include ALD reactors equipped with appropriate devices and means for delivering precursors, as well as CVD reactors. According to some embodiments, showerhead reactors can be used.

Examples of suitable reactors that can be used include commercially available single substrate (or single wafer) deposition equipment, such as Pulsar® reactors (e.g., Pulsar® 2000, Pulsar® 3000, and Pulsar® XP ALD, etc.), and EmerALD® XP and EmerALD® reactors, available from ASM America, Inc., Phoenix, Arizona, and ASM Europe BV, Almere, The Netherlands. Other commercially available reactors include reactors sold under the trade names Eagle® XP and XP8, manufactured by ASM Japan Co., Ltd. (Tokyo, Japan). In some embodiments, the reactor is a spatial ALD reactor in which the substrate moves or rotates during processing.

In some embodiments, a batch reactor may be used. Suitable batch reactors include, but are not limited to, Advance® 400 series reactors available from ASM Europe BV (Almere, The Netherlands) under the trade names A400 and A412PLUS. In some embodiments, a vertical batch reactor such as the A412 is utilized in which the boat rotates within the reactor during processing. Thus, in some embodiments, the wafers rotate during processing. In other embodiments, the batch reactor comprises a mini-batch reactor configured to accommodate 10 or less wafers, 8 or less wafers, 6 or less wafers, 4 or less wafers, or 2 wafers. In some embodiments in which a batch reactor is used, the wafer-to-wafer uniformity is less than 3% (1 sigma), less than 2%, less than 1% or even less than 0.5%.

The deposition processes described herein can be optionally carried out in reactors or reaction spaces connected to a cluster tool. In a cluster tool, each reaction space is dedicated to one type of process, so the temperature of the reaction space in each module can be kept constant, improving throughput compared to reactors that heat the substrate to a process temperature before each run. Additionally, a cluster tool can reduce the time it takes to evacuate the reaction space to the desired process pressure level between substrates.

A stand-alone reactor is equipped with a load lock, in which case there is no need to cool the reaction space between runs. In some embodiments, a deposition process for depositing thin films, including metallic films, can include multiple deposition cycles, such as ALD cycles.

In some embodiments, a cyclical deposition process is used to form a metallic film on a substrate, and the cyclical deposition process can be an ALD type process. In some embodiments, the cyclical deposition can be a hybrid ALD/CVD or cyclical CVD process. For example, in some embodiments, the growth rate of an ALD process can be low compared to a CVD process. One approach to increase the growth rate is to operate at a higher substrate temperature than typically used in an ALD process, resulting in a chemical vapor deposition process, but further utilizing sequential introduction of precursors, such a process can be referred to as a cyclical CVD.

In some embodiments, the metal precursor, also referred to herein as a "metal compound," can include a halogen-free metal precursor. That is, the metal precursor is substantially free of halogen species. In some embodiments, the halogen-free metal precursor can include one of copper, cobalt, and nickel. Thus, the halogen-free metal precursor can be Cu(dmap)₂(dmap = dimethylamino-2-propoxide), Ni(dmap)₂, or Co(dmap)₂Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand, in which the central metal atom is bonded through at least one oxygen and at least one nitrogen atom in the bidentate ligand. Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand, in which the central metal atom is bonded through at least one nitrogen atom in the bidentate ligand. Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand and at least one other ligand, such as a monodentate ligand. Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand and at least two other ligands, such as a monodentate ligand, that are bonded to the central metal atom through N or O. Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand and at least one other ligand, such as a monodentate ligand that is bonded to the central metal atom through N or O. Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand, in which the central metal atom is bonded through at least one nitrogen atom and at least one atom other than the nitrogen of the bidentate ligand. Thus, in some embodiments, the halogen-free metal precursor may include at least one bidentate ligand, in which the central metal atom is bonded through two nitrogen atoms in the bidentate ligand. In some embodiments, the halogen-free metal precursor includes at least two bidentate ligands. In some embodiments, the halogen-free metal precursor includes two bidentate ligands. Some examples of suitable halide-free β-diketiminato (e.g., Ni(pda)2), (pda=pentane-2,4-diketiminato) compounds are described in U.S. Patent Publication No. 2009/0197411 A1, the disclosure of which is incorporated herein in its entirety. Some examples of suitable halide-free amidinate compounds (e.g., Ni(iPr-AMD)2) are described in U.S. Patent Application Publication No. 2006/0141155 A1, the disclosure of which is incorporated herein in its entirety. Some examples of suitable halide-free iminoalkoxide compounds are described in U.S. Patent Publication No. 2014/0227444 A1, the disclosure of which is incorporated herein in its entirety. In some embodiments, the halogen-free metal precursor does not contain metal atoms other than the desired metal (Co, Ni, Cu). In some embodiments, the metal in the halogen-free metal precursor has an oxidation state of 0. In some embodiments, the metal in the halogen-free metal precursor has an oxidation state of +I. In some embodiments, the metal in the halogen-free metal precursor has an oxidation state of +III. In some embodiments, the metal in the halogen-free metal precursor has an oxidation state of +II. In some embodiments, the oxidation state is the oxidation state of the metal in the precursor at room temperature. The oxidation state may change under different conditions, such as under different pressures, temperatures, and/or atmospheres, and when contacted with different surface materials under the different conditions. In some embodiments, the halogen-free metal precursor does not include halides such as F, Cl, Br, and I. In some embodiments, the halogen-free metal precursor includes carbon, hydrogen, and nitrogen, and optionally oxygen.

In some embodiments, the halide-free copper precursor is, for example, Cu(dmap).₂or copper(I) N,N'-diisopropylacetamidinate. In some embodiments, the copper precursor may be a copper β-diketonate compound, a copper β-diketiminato compound, a copper aminoalkoxide compound, such as Cu(dmae)₂, Cu(deap)₂or Cu(dmamb)₂, copper amidinate compounds, e.g., Cu(^sBu-amd)]₂, copper cyclopentadienyl compounds, copper carbonyl compounds, and combinations thereof. In some embodiments, X(acac)_yor X(thd)_yCompounds are used where X is copper, y is typically but not necessarily 2 or 3, and thd is 2,2,6,6-tetramethyl-3,5-heptanedionate. In some embodiments, the halide-free copper precursor is copper(II) acetate, [Cu(HMDS)]4 or Cu(nhc)HMDS (1,3-di-isopropyl-imidazolin-2-ylidenecopper hexamethyldisilazide), or a Cu-β-diketiminate, such as Cu(dki)VTMS (dki=diketiminate).

In some embodiments, the halide-free nickel precursor can be, for example, bis(4-N-ethylamino-3-pentene-2-N-ethyliminonato)nickel(II). In some embodiments, the nickel precursor can be selected from the group consisting of nickel β-diketonate compounds, nickel β-diketiminato compounds, nickel aminoalkoxide compounds, nickel amidinate compounds, nickel cyclopentadienyl compounds, nickel carbonyl compounds, and combinations thereof. In some embodiments, X(acac)_yor X(thd)_yThe compound is used where X is nickel, y is typically but not necessarily 2 or 3, and thd is 2,2,6,6-tetramethyl-3,5 heptanedionate.

In some embodiments, the Co precursor is a Co β-diketoiminate compound. In some embodiments, the Co precursor is a Co ketoiminate compound. In some embodiments, the Co precursor is a Co amidinate compound. In some embodiments, the Co precursor is a Co β-diketoiminate compound. In some embodiments, the Co precursor comprises at least one ketoimine ligand or derivatives thereof. In some embodiments, the Co precursor comprises at least one amidine ligand or derivatives thereof. In some embodiments, the Co precursor comprises at least one ketonate ligand or derivatives thereof. In some embodiments, the Co precursor is Co₂(CO)₈, CCTBA, CoCp₂, Co(Cp-amd), Co(Cp(CO)₂), tBu-AllylCo(CO)₃, or Co(HMDS)₂It is.

In some embodiments, exposing the substrate to a halogen-free metal precursor results in the deposition of a metal precursor (e.g., Cu(dmap)) on the substrate.₂) for a time period between about 0.01 seconds and about 60 seconds, between about 0.05 seconds and about 10.0 seconds, between about 0.1 seconds and about 5.0 seconds. Further, during the pulsed injection of the metal precursor onto the substrate, the flow rate of the metal precursor can be less than 2000 sccm, or less than 1000 sccm, or less than 500 sccm, or less than 200 sccm, or even less than 100 sccm.

Excess metal precursor and any reaction by-products may be removed from the surface of the substrate, for example, by purging with an inert gas. For example, in some embodiments of the present disclosure, the method may include a purge cycle in which the surface of the substrate is purged for a time period of less than about 1.0 seconds. Excess metal precursor and any reaction by-products may be removed using a vacuum generated by a pumping device.

In the second stage of the deposition cycle (the "substituted hydrazine stage"), the substrate is contacted with a second gas phase reactant comprising a hydrocarbon-substituted hydrazine precursor. In some embodiments of the present disclosure, the method can further comprise selecting the substituted hydrazine to comprise an alkyl group having at least four carbon atoms, where "alkyl group" refers to a saturated or unsaturated hydrocarbon chain of at least four carbon atoms in length, such as, but not limited to, butyl, pentyl, hexyl, heptyl, and octyl, and isomers thereof, such as their n-, iso-, sec-, and tert-isomers. The alkyl group can be linear or branched and can encompass all structural isomeric forms of the alkyl group. In some embodiments, the alkyl chain can be substituted. In some embodiments of the present disclosure, the alkyl hydrazine can comprise at least one hydrogen bonded to the nitrogen. In some embodiments of the present disclosure, the alkyl hydrazine can comprise at least two hydrogens bonded to the nitrogen. In some embodiments of the present disclosure, the alkyl hydrazine may include at least one hydrogen attached to the nitrogen and at least one alkyl chain attached to the nitrogen. In some embodiments of the present disclosure, the second reactant may include an alkyl hydrazine and further include one or more tert-butyl hydrazines (C₄H₉N₂H₃), dimethylhydrazine, or diethylhydrazine. In some embodiments of the present disclosure, the substituted hydrazine has at least one hydrocarbon group bonded to the nitrogen. In some embodiments of the present disclosure, the substituted hydrazine has at least two hydrocarbon groups bonded to the nitrogen. In some embodiments of the present disclosure, the substituted hydrazine has at least three hydrocarbon groups bonded to the nitrogen. In some embodiments of the present disclosure, the substituted hydrazine has at least one C1-C3 hydrocarbon group bonded to the nitrogen. In some embodiments of the present disclosure, the substituted hydrazine has at least one C4-C10 hydrocarbon group bonded to the nitrogen. In some embodiments of the present disclosure, the substituted hydrazine has a straight chain, branched chain, or cyclic or aromatic hydrocarbon group bonded to the nitrogen. In some embodiments of the present disclosure, the substituted hydrazine includes a substituted hydrocarbon group bonded to the nitrogen.

In some embodiments of the present disclosure, the substituted hydrazine has the formula: R^IR^II-N-NR^IIIR^IV, (1)

Here, R^Ican be selected from hydrocarbon groups, such as linear, branched, cyclic, aromatic or substituted hydrocarbon groups, and R^IIGroup, R^IIIGroup, R^IVEach of the groups can be independently selected to be a hydrogen group or a hydrocarbon group, such as a straight chain, branched chain, cyclic, aromatic or substituted hydrocarbon group.

In some embodiments of formula (1), R^I, R^II, R^III, R^IVEach of R can be a C1-C10 hydrocarbon, a C1-C3 hydrocarbon, a C4-C10 hydrocarbon, or hydrogen, such as a straight chain, branched chain, cyclic, aromatic, or substituted hydrocarbon group.^I, R^II, R^III, R^IVAt least one of the groups comprises an aromatic group, such as a phenyl group. In some embodiments, R^I, R^II, R^III, R^IVAt least one of the groups comprises a methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, tert-butyl group, or a phenyl group.^I, R^II, R^III, R^IVAt least two of the groups can be independently selected to include a methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, tert-butyl group, or a phenyl group.^II, R^IIIand R^IVIn some embodiments, R^II, R^IIIand R^IVAt least one of the two groups is hydrogen. In some embodiments, R^II, R^IIIand R^IVAt least one of the groups is hydrogen. In some embodiments, R^II, R^IIIand R^IVAll of the groups are hydrogen.

In some embodiments, exposing the substrate to a substituted hydrazine precursor comprises pulsing the substituted hydrazine precursor (e.g., tertbutylhydrazine) onto the substrate for a time period between 0.1 seconds and 2.0 seconds, or between about 0.01 seconds and about 10 seconds, or less than about 20 seconds, less than about 10 seconds, or less than about 5 seconds. Further, during pulsing of the substituted hydrazine precursor onto the substrate, the flow rate of the substituted hydrazine precursor can be less than 2000 sccm, or less than 1000 sccm, or less than 500 sccm, or even less than 100 sccm.

The second gas phase reactant, which includes a substituted hydrazine precursor, can react with the metal-containing molecules remaining on the surface of the substrate. In some embodiments, the second stage substituted hydrazine precursor can include a reducing agent that can reduce the metal-containing molecules remaining on the surface of the substrate, thereby forming a metallic film. For example, the first gas phase reactant can include a copper precursor, and the second gas phase reactant can include a reducing agent. After the copper precursor is introduced into the reaction chamber and adsorbed on the surface of the substrate, the excess copper precursor vapor can be evacuated or purged from the chamber. This process is followed by the introduction of a reducing agent that reacts with the copper precursor on the surface of the substrate to form copper metal and free form ligands. This deposition cycle can be repeated as necessary to achieve the desired thickness of the metallic film.

For example, excess second source chemical and reaction by-products, if any, may be removed from the surface of the substrate by pulsing a purge gas and/or a vacuum created by an evacuation system. The purge gas may be any inert gas, such as argon (Ar), nitrogen (N₂) or helium (He), etc. One stage is generally considered to follow immediately after another stage if there is an intervening purge (i.e., purge gas pulse) or other reactant removal step.

The deposition cycle of alternately contacting the substrate with a first gas phase reactant (i.e., a halogen-free metal precursor) and a second gas phase reactant (i.e., a substituted hydrazine precursor) can be repeated two or more times until a metallic film of a desired thickness is deposited. Of course, in some embodiments of the present disclosure, the order of contacting the substrate with the first gas phase reactant and the second gas phase reactant can be such that the substrate is first contacted with the second gas phase reactant followed by contact with the first gas phase reactant. Furthermore, in some embodiments, the cyclic deposition process can include contacting the substrate with the first gas phase reactant one or more times before contacting the substrate with the second gas phase reactant one or more times, or equivalently, can include contacting the substrate with the second gas phase reactant one or more times before contacting the substrate with the first gas phase reactant one or more times. Further, some embodiments of the present disclosure may include selecting the first gas phase reactant and the second gas phase reactant to be free of plasma reactants, e.g., the first and second gas phase reactants are substantially free of ionized reactants. In some embodiments, the first and second gas phase reactants are substantially free of ionized reactants, excited species, and radical species. For example, both the first gas phase reactant and the second gas phase reactant may be free of plasma reactants to prevent ionization damage and associated defects of the underlying substrate.

The cyclic deposition processes described herein utilizing halogen-free metal precursors and substituted hydrazine precursors to form metallic films can be carried out in an ALD or CVD deposition system with a heated substrate. For example, in some embodiments, the method can include heating the substrate to a temperature of about 80°C to about 140°C, or further heating the substrate to a temperature of about 80°C to about 120°C. Of course, the appropriate temperature window for any given cyclic deposition process, such as an ALD reaction, will depend on the surface termination and reactant species involved, where the temperature varies depending on the precursors used and is generally no greater than about 700°C, in some embodiments the deposition temperature is generally no less than about 100°C for vapor deposition processes, in some embodiments the deposition temperature is about 100°C to about 250°C, in some embodiments the deposition temperature is about 120°C to about 200°C. In some embodiments the deposition temperature is less than about 500°C, less than about 400°C, or less than about 300°C. In some examples, for example, when additional reactants or reducing agents are used in the process, such as hydrogen-containing reactants or reducing agents, the deposition temperature can be less than about 200° C., less than about 150° C., or less than about 100° C. In some cases, the deposition temperature can be greater than about 20° C., greater than about 50° C., and greater than about 75° C.

The thin film comprising a metallic film deposited according to some embodiments described herein may be a continuous thin film comprising a metallic film. In some embodiments, the thin film comprising a metallic film deposited according to some embodiments described herein may be continuous with a thickness of less than about 100 nm, less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, or less than about 20 nm, or less than about 15 nm, or less than about 10 nm, or less than about 5 nm or less. The continuity referred to herein may be physical continuity or electrical continuity. In some embodiments, the thickness at which a film may be physically continuous may not be the same as the thickness at which a film is electrically continuous, and the thickness at which a film may be electrically continuous may not be the same as the thickness at which a film is physically continuous.

In some embodiments, thin films comprising metallic films deposited according to some embodiments described herein can be continuous, although in some embodiments it may be desirable to form discontinuous thin films comprising metallic films, or thin films comprising isolated islands comprising metallic films, or thin films comprising nanoparticles comprising metallic films. In some embodiments, the deposited thin films comprising metallic films may comprise nanoparticles comprising copper, nickel, or cobalt that are substantially not physically or electrically continuous with one another. In some embodiments, the deposited thin films comprising metallic films may comprise isolated nanoparticles or isolated islands comprising metallic films.

In some embodiments, thin films including metallic films deposited according to some embodiments described herein can have an electrical resistivity of less than about 20 μΩcm at a thickness of less than about 100 nm. In some embodiments, thin films including metallic films deposited according to some embodiments described herein can have an electrical resistivity of less than about 20 μΩcm at a thickness of less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, or less than about 20 nm or less. In some embodiments, thin films including metallic films deposited according to some embodiments described herein can have an electrical resistivity of less than about 15 μΩcm at a thickness of less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, or less than about 20 nm or less. In some embodiments, thin films, including metallic films, deposited according to some embodiments described herein can have an electrical resistivity of less than about 10 μΩ cm at a thickness of less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, or less than about 20 nm or less.

In some embodiments, thin films, including metallic films, deposited according to some embodiments described herein can have an electrical resistivity of less than about 200 μΩ cm at a thickness of less than about 30 nm, less than about 20 nm, less than about 15 nm, less than about 10 nm, less than about 8 nm, or less than about 5 nm or less.

In some embodiments, metallic thin films deposited according to some embodiments described herein can have an electrical resistivity of less than about 200 μΩcm, less than about 100 μΩcm, less than about 50 μΩcm, less than about 30 μΩcm, less than about 20 μΩcm, less than about 18 μΩcm, less than about 15 μΩcm, less than about 12 μΩcm, less than about 10 μΩcm, or less than about 8 μΩcm at a thickness of less than about 100 nm.

In some embodiments, thin films comprising copper deposited according to some embodiments described herein can have an electrical resistivity of less than about 200 μΩcm, less than about 100 μΩcm, less than about 50 μΩcm, less than about 30 μΩcm, less than about 20 μΩcm, less than about 18 μΩcm, less than about 15 μΩcm, less than about 12 μΩcm, less than about 10 μΩcm, less than about 8 μΩcm, or less than about 5 μΩcm or less at a thickness of less than about 100 nm. In some embodiments, thin films comprising copper deposited according to some embodiments described herein can have an electrical resistivity of less than about 20 μΩcm, less than about 18 μΩcm, less than about 15 μΩcm, less than about 12 μΩcm, less than about 10 μΩcm, less than about 8 μΩcm, or less than about 5 μΩcm or less at a thickness of less than about 50 nm. In some embodiments of the present disclosure, forming a metallic film (e.g., a copper film) can include forming the metallic film to have an electrical resistivity of less than about 4 μΩcm, or an electrical resistivity of less than 3 μΩcm, or even an electrical resistivity of less than 2 μΩcm. As a non-limiting example, a copper film can be formed by the methods of the present disclosure to a thickness of about 50 nanometers with an electrical resistivity of about 1.92 μΩcm.

In some embodiments, thin films comprising nickel or cobalt deposited according to some embodiments described herein can have an electrical resistivity of less than about 200 μΩcm, less than about 100 μΩcm, less than about 50 μΩcm, less than about 30 μΩcm, less than about 20 μΩcm, less than about 18 μΩcm, less than about 15 μΩcm, less than about 12 μΩcm, less than about 10 μΩcm, or less than about 8 μΩcm at a thickness of less than about 100 nm. In some embodiments, thin films comprising nickel or cobalt deposited according to some embodiments described herein can have an electrical resistivity of less than about 20 μΩcm, less than about 18 μΩcm, less than about 15 μΩcm, less than about 12 μΩcm, less than about 10 μΩcm, or less than about 8 μΩcm at a thickness of less than about 50 nm.

In some embodiments, the copper, nickel or cobalt-containing thin films deposited according to some embodiments described herein can be crystalline or polycrystalline. In some embodiments, the copper, nickel or cobalt-containing thin films deposited according to some embodiments described herein can have a cubic crystal structure. In some embodiments, the copper, nickel or cobalt-containing thin films deposited according to some embodiments described herein can have a thickness of about 20 nm to about 100 nm. In some embodiments, the copper, nickel or cobalt-containing thin films deposited according to some embodiments described herein can have a thickness of about 20 nm to about 60 nm. In some embodiments, the copper, nickel or cobalt-containing thin films deposited according to some embodiments described herein can have a thickness of more than about 20 nm, more than about 30 nm, more than about 40 nm, more than about 50 nm, more than about 60 nm, more than about 100 nm, more than about 250 nm, more than about 500 nm, or more. In some embodiments, thin films comprising copper, nickel or cobalt deposited according to some embodiments described herein can have a thickness of less than about 50 nm, less than about 30 nm, less than about 20 nm, less than about 15 nm, less than about 10 nm, less than about 5 nm, or in some cases the amount of copper, nickel or cobalt corresponds to a thickness of less than about 5 nm, less than about 3 nm, less than about 2 nm, or less than about 1 nm, for example, when a discontinuous film or isolated particles or islands comprising copper, nickel or cobalt are desired.

In some embodiments, the metallic film growth rate is between about 0.005 Å/cycle and about 5 Å/cycle, between about 0.01 Å/cycle and about 2.0 Å/cycle. In some embodiments, the film growth rate is greater than about 0.05 Å/cycle, greater than about 0.1 Å/cycle, greater than about 0.15 Å/cycle, greater than about 0.20 Å/cycle, greater than about 0.25 Å/cycle, or greater than about 0.3 Å/cycle. In some embodiments, the film growth rate is less than about 2.0 Å/cycle, less than about 1.0 Å/cycle, less than about 0.75 Å/cycle, less than about 0.5 Å/cycle, or less than 0.3 Å/cycle.

In some embodiments, the thin film containing copper, nickel, or cobalt may contain less than about 20 at%, less than about 10 at%, less than about 7 at%, less than about 5 at%, less than about 3 at%, less than about 2 at%, or less than about 1 at% impurities, i.e., elements other than Cu, Ni, and Co, or elements other than the metal of the desired metallic film. In some embodiments, the thin film containing copper, nickel, or cobalt may contain less than about 20 at%, less than about 10 at%, less than about 5 at%, less than about 2 at%, or less than about 1 at% hydrogen. In some embodiments, the thin film containing copper, nickel, or cobalt may contain less than about 10 at%, less than about 5 at%, less than about 2 at%, less than about 1 at%, or less than about 0.5 at% carbon. In some embodiments, the thin film containing copper, nickel, or cobalt may contain less than about 5 at%, less than about 2 at%, less than about 1 at%, less than about 0.5 at%, or less than about 0.2 at% nitrogen. In some embodiments, the thin film containing copper, nickel or cobalt may contain less than about 15 at%, less than about 10 at%, less than about 5 at%, less than about 3 at%, less than about 2 at%, or less than about 1 at% oxygen. In some embodiments, the thin film containing copper, nickel or cobalt may contain less than about 30 at%, less than about 20 at%, less than about 20 at%, less than about 5 at%, or less than about 3 at% oxygen on the surface of the copper, nickel or cobalt, the surface being understood to be less than about 20 nm thick from the top surface. In some embodiments, the thin film containing copper, nickel or cobalt may contain stoichiometric or non-stoichiometric copper oxide, nickel oxide or cobalt oxide near the top surface of the material. In some embodiments, thin films comprising copper, nickel or cobalt may comprise greater than about 80 at%, greater than about 90 at%, greater than about 93 at%, greater than about 95 at%, greater than about 97 at%, or greater than about 99 at% copper, nickel or cobalt. By way of non-limiting example, Figure 4 shows a graph illustrating time-of-flight elastic recoil detection analysis (TOF-ERDA) of a copper film formed according to an embodiment of the present disclosure.

The metallic film formed by the embodiments of the present disclosure may include one of copper, cobalt, and nickel. In some embodiments of the present disclosure, the metallic film formed may consist essentially of one of copper, cobalt, and nickel. For example, as a non-limiting exemplary embodiment, the metallic film formed by the method of the present disclosure may include copper having an elemental composition of more than 95.0 atomic %, or more than 97.0 atomic %, or more than 98.0 atomic %, or more than 99.0 atomic %, or even more than 99.5 atomic % copper. In some embodiments, the copper surface may be oxidized, and the above values represent the values of the bulk film without surface oxidation. In the embodiments outlined herein, the atomic concentration of the elements may be determined using Rutherford backscattering (RBS) or time-of-flight elastic recoil detection analysis (TOF-ERDA). If some other method is used, such as X-ray photoelectron spectroscopy (XPS), the atomic concentration may vary.

In some embodiments, thin films comprising copper, nickel or cobalt may be deposited on three-dimensional structures, in some embodiments, the step coverage of the thin films comprising copper, nickel or cobalt is about 50% or more, about 80% or more, about 90% or more, about 95%, about 98%, or about 99% or more in structures with aspect ratios (height/width) of greater than about 2, greater than about 5, greater than about 10, greater than about 25, greater than about 50, or greater than about 100.

In some embodiments of the present disclosure, metallic films formed by the methods described herein can have desired crystallographic properties. For example, as a non-limiting exemplary embodiment, the metallic film can consist essentially of copper, and the copper film can include a cubic crystal structure with a preferred (111) crystallographic orientation. More specifically, FIG. 1 is a graph showing 2θ X-ray diffraction (XRD) scans of non-limiting exemplary metallic copper films formed by the ALD processes of the present disclosure utilizing halogen-free metal precursors and alkylhydrazine precursors at various deposition temperatures. For example, the XRD scan shown at 100 shows Cu(dmap) at a substrate temperature of 140° C.₂and tert-butylhydrazine. The XRD scan shown in representation 100 indicates that the copper film formed by the methods of the present disclosure may include several crystallographic orientations, including (111) and (200), with the (111) crystallographic orientation being the preferred orientation. Thus, in some embodiments of the present disclosure, the metallic film formed by the ALD processes described herein includes a (111) crystallographic orientation, and in some embodiments, the metallic film includes a preferred (111) crystallographic orientation.

In some embodiments, the deposited thin film including the metallic film can undergo a treatment process after deposition. In some embodiments, the treatment process can, for example, increase the electrical conductivity or continuity of the deposited thin film including the metallic film. In some embodiments, the treatment process can, for example, include an annealing process. In some embodiments, the thin film including the metallic film can be annealed in a vacuum or in an atmosphere including one or more annealing gases, such as reducing gases including hydrogen. In some embodiments, the metallic film can include nitrogen and annealing/treatment in a vacuum or annealing gas, such as in a reducing gas, at an elevated temperature, such as the deposition reaction temperature of the metallic film, to reduce or almost completely remove nitrogen from the metallic film. In some embodiments, the treatment with a reducing gas is performed every cycle, every nth cycle, where n is more than 1, 2, 3, 4, 9, 19, 49 or 99 cycles, or after the metallic film deposition as a post-treatment. The nitrogen-containing metallic film before treatment may contain less than about 60 at%, less than about 50 at%, less than about 40 at%, less than about 30 at%, less than about 20 at%, less than about 10 at%, or less than about 5 at% nitrogen. In some embodiments, the nitrogen-containing metallic film after treatment may contain less than about 20 at%, less than about 10 at%, less than about 5 at%, less than about 2 at%, less than about 1 at%, less than about 0.5 at%, or less than about 0.2 at% nitrogen.

Metallic films formed by the cyclic deposition processes disclosed herein can be utilized in a variety of contexts, such as in the formation of semiconductor device structures.

Those skilled in the art will recognize that the processes described herein are applicable in many contexts, including the fabrication of planar devices and transistors, including multiple gate transistors such as FinFETs.

2, a semiconductor device structure 200 can include an interconnect structure that can include a substrate 202, a barrier layer 204, a dielectric layer 206, a seed layer 208, and a fill layer 210. In accordance with the teachings of the present disclosure, the seed layer 208 can include a metallic film, such as a metallic copper film, formed by the cyclic deposition process described herein.

More specifically, the semiconductor device structure 200 may include a substrate 202, which may include a silicon material including device circuitry (not shown) formed within the substrate 202. The barrier layer 204 may include an etch stop layer, such as silicon carbide, silicon nitride, silicon oxycarbide, and silicon oxynitride. The dielectric layer 206 may include an interlevel dielectric material, such as silicon dioxide, silicon nitride, polymer-based materials, and carbon-rich dielectrics.

In some embodiments of the present disclosure, the semiconductor device structure 200 can include a seed layer 208, the seed layer consisting essentially of copper formed by the cyclic deposition process described herein. The seed layer can be formed to a thickness of less than about 20 nanometers, or less than about 10 nanometers, or even less than about 5 nanometers. Furthermore, the seed layer can be formed to have an electrical resistivity of less than about 50 μΩcm, less than about 20 μΩcm, less than about 10 μΩcm, less than about 5 μΩcm, less than about 4 μΩcm, or less than 3 μΩcm, or even less than 2 μΩcm.

The embodiments of the present disclosure may also include a reaction system configured to form the metallic films of the present disclosure. More specifically, FIG. 3 illustrates a schematic of a reaction system 300 including a reaction chamber 302 that holds a substrate (not shown) under predetermined pressure, temperature, and ambient conditions and further includes mechanisms for selectively exposing the substrate to various gases. A precursor reactant source 304 may be connected to the reaction chamber 302 by a conduit or other suitable means 304A, and further includes a manifold, valve control system, mass flow control system, or mechanism for controlling gaseous precursors originating from the precursor reactant source 304. The precursors (not shown), reactants (not shown) provided by the precursor reactant source 304 may be liquids or solids under room temperature and standard atmospheric pressure conditions. Such precursors may be vaporized in a vacuum vessel of the reactant source, and the precursors may be maintained above the vaporization temperature in the precursor source chamber. In such an embodiment, the vaporized precursors may be vaporized in a carrier gas (e.g., an inactive gas or an inert gas) or a gaseous gas (e.g., a gaseous ... The precursor may be transported in a gas (gas) and delivered into the reaction chamber 302 through conduit 304A. In other embodiments, the precursor may be gaseous under standard conditions. In such embodiments, the precursor does not need to be vaporized and does not require a carrier gas. For example, in one embodiment, the precursor may be stored in a gas cylinder. As noted above, the reaction system 300 may also include an additional precursor reactant source, such as precursor reactant source 306, which may also be coupled to the reaction chamber by conduit 306A.

A purge gas source 308 is also coupled to the reaction chamber 302 through conduit 308A to selectively supply various inert or noble gases to the reaction chamber 302 to assist in the removal of precursor or waste gases from the reaction chamber. The various inert or noble gases that may be supplied may come from solid, liquid or stored gaseous forms.

The reaction system 300 of FIG. 3 may also include a system operation and control mechanism 310 that provides electronic circuitry and mechanical components for selectively operating the valves, manifolds, pumps, and other devices included in the reaction system 300. Such circuits and components operate to introduce precursors, purge gases from respective precursor sources 304, 306, and purge gas source 308. The system operation and control mechanism 310 also controls the timing of gas pulse sequences, substrate and reaction chamber temperatures, reaction chamber pressure, and various other operations required to properly operate the reaction system 300. The operation and control mechanism 310 may include control software and electrical or pneumatic control valves for controlling the flow of precursors, reactants, and purge gases into and out of the reaction chamber 302. The control system may include software or hardware components, such as modules, such as FPGAs or ASICs, that perform specific tasks. The modules may be advantageously configured to reside on an addressable storage medium of the control system and configured to perform one or more processes.

Those skilled in the relevant art will appreciate that other configurations of the present reaction system are possible, including different numbers and types of precursor reactant sources and purge gas sources. Moreover, such skilled artisans will appreciate that there are many arrangements of valves, conduits, precursor sources, and purge gas sources that may be used to achieve the goal of selectively delivering gases into the reaction chamber 302. Moreover, as a simplified illustration of the reaction system, many components are omitted for ease of illustration. Such components may include, for example, various valves, manifolds, purifiers, heaters, reservoirs, vents, and/or bypasses.

The illustrative embodiments of the above disclosure do not limit the scope of the present invention, since these embodiments are merely examples of embodiments of the present invention, as defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of the present invention. Indeed, various modifications of the present disclosure in addition to those shown and described herein, such as alternative useful combinations of the described elements, will become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

The present invention includes the following aspects.

[1]

1. A method of forming a metallic film on a substrate by cyclic deposition, the method comprising: contacting the substrate with a first reactant comprising a halogen-free metal precursor comprising at least one of copper, nickel, or cobalt; and contacting the substrate with a second reactant comprising a hydrocarbon-substituted hydrazine precursor.

[2]

The method of any one of claims 1 to 5, wherein the cyclic deposition comprises atomic layer deposition.

[3]

The method of any one of claims 1 to 5, wherein the cyclic deposition comprises cyclic chemical vapor deposition.

[4]

The method of claim 1, further comprising selecting the substituted hydrocarbyl hydrazine precursor to contain a C1-C10 hydrocarbyl group.

[5]

The method of claim 1, further comprising selecting the substituted hydrocarbon hydrazine precursor to include an aromatic hydrocarbon group.

[6]

The method of claim 1, further comprising selecting the substituted hydrocarbon hydrazine precursor to include at least one alkyl group.

[7]

The method of [6], further comprising selecting the alkyl group to include at least one of a methyl, ethyl, or tert-butyl alkyl group.

[8]

The method of claim 1, further comprising selecting the halogen-free metal precursor to include at least one bidentate ligand.

[9]

The method of claim 1, further comprising selecting the halogen-free metal precursor to include at least one ligand that is bonded to a metal atom through at least one oxygen atom and at least one nitrogen atom.

[10]

The method of claim 1, further comprising selecting the halogen-free metal precursor to include at least two halogen-free ligands.

[11]

Cu(dmap)₂, Ni(dmap)₂, or Co(dmap)₂The method of claim 1, further comprising selecting the halogen-free metal precursor to include at least one of:

[12]

2. The method of claim 1, wherein the method comprises at least one deposition cycle of alternately and sequentially contacting the substrate with the first reactant and the second reactant.

[13]

The method of claim 7, wherein the deposition cycle is repeated two or more times.

[14]

13. The method of claim 1, further comprising forming the metallic film to have an electrical resistivity of less than 10 μΩ cm.

[15]

2. The method of claim 1, further comprising forming the metallic film to have an electrical resistivity of less than 10 μΩ cm at a thickness of less than 50 nm.

[16]

The method of [1], further comprising heating the substrate to a temperature of less than about 500°C.

[17]

The method of claim 8, further comprising heating the substrate to a temperature greater than about 50°C.

[18]

13. The method of claim 1, further comprising selecting the first reactant and the second reactant such that they do not comprise a plasma reactant.

[19]

13. The method of claim 1, further comprising selecting the metallic film to include at least one of copper, cobalt, or nickel.

[20]

A reaction system configured to carry out the method of [1].

[21]

A semiconductor device structure comprising at least a portion of a metallic interconnect formed by the method of [1].